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TOMOYO Linux Cross Reference
Linux/fs/btrfs/inode.c

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  1 /*
  2  * Copyright (C) 2007 Oracle.  All rights reserved.
  3  *
  4  * This program is free software; you can redistribute it and/or
  5  * modify it under the terms of the GNU General Public
  6  * License v2 as published by the Free Software Foundation.
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 11  * General Public License for more details.
 12  *
 13  * You should have received a copy of the GNU General Public
 14  * License along with this program; if not, write to the
 15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 16  * Boston, MA 021110-1307, USA.
 17  */
 18 
 19 #include <linux/kernel.h>
 20 #include <linux/bio.h>
 21 #include <linux/buffer_head.h>
 22 #include <linux/file.h>
 23 #include <linux/fs.h>
 24 #include <linux/pagemap.h>
 25 #include <linux/highmem.h>
 26 #include <linux/time.h>
 27 #include <linux/init.h>
 28 #include <linux/string.h>
 29 #include <linux/backing-dev.h>
 30 #include <linux/mpage.h>
 31 #include <linux/swap.h>
 32 #include <linux/writeback.h>
 33 #include <linux/compat.h>
 34 #include <linux/bit_spinlock.h>
 35 #include <linux/xattr.h>
 36 #include <linux/posix_acl.h>
 37 #include <linux/falloc.h>
 38 #include <linux/slab.h>
 39 #include <linux/ratelimit.h>
 40 #include <linux/mount.h>
 41 #include <linux/btrfs.h>
 42 #include <linux/blkdev.h>
 43 #include <linux/posix_acl_xattr.h>
 44 #include <linux/uio.h>
 45 #include "ctree.h"
 46 #include "disk-io.h"
 47 #include "transaction.h"
 48 #include "btrfs_inode.h"
 49 #include "print-tree.h"
 50 #include "ordered-data.h"
 51 #include "xattr.h"
 52 #include "tree-log.h"
 53 #include "volumes.h"
 54 #include "compression.h"
 55 #include "locking.h"
 56 #include "free-space-cache.h"
 57 #include "inode-map.h"
 58 #include "backref.h"
 59 #include "hash.h"
 60 #include "props.h"
 61 #include "qgroup.h"
 62 #include "dedupe.h"
 63 
 64 struct btrfs_iget_args {
 65         struct btrfs_key *location;
 66         struct btrfs_root *root;
 67 };
 68 
 69 struct btrfs_dio_data {
 70         u64 outstanding_extents;
 71         u64 reserve;
 72         u64 unsubmitted_oe_range_start;
 73         u64 unsubmitted_oe_range_end;
 74         int overwrite;
 75 };
 76 
 77 static const struct inode_operations btrfs_dir_inode_operations;
 78 static const struct inode_operations btrfs_symlink_inode_operations;
 79 static const struct inode_operations btrfs_dir_ro_inode_operations;
 80 static const struct inode_operations btrfs_special_inode_operations;
 81 static const struct inode_operations btrfs_file_inode_operations;
 82 static const struct address_space_operations btrfs_aops;
 83 static const struct address_space_operations btrfs_symlink_aops;
 84 static const struct file_operations btrfs_dir_file_operations;
 85 static const struct extent_io_ops btrfs_extent_io_ops;
 86 
 87 static struct kmem_cache *btrfs_inode_cachep;
 88 struct kmem_cache *btrfs_trans_handle_cachep;
 89 struct kmem_cache *btrfs_path_cachep;
 90 struct kmem_cache *btrfs_free_space_cachep;
 91 
 92 #define S_SHIFT 12
 93 static const unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = {
 94         [S_IFREG >> S_SHIFT]    = BTRFS_FT_REG_FILE,
 95         [S_IFDIR >> S_SHIFT]    = BTRFS_FT_DIR,
 96         [S_IFCHR >> S_SHIFT]    = BTRFS_FT_CHRDEV,
 97         [S_IFBLK >> S_SHIFT]    = BTRFS_FT_BLKDEV,
 98         [S_IFIFO >> S_SHIFT]    = BTRFS_FT_FIFO,
 99         [S_IFSOCK >> S_SHIFT]   = BTRFS_FT_SOCK,
100         [S_IFLNK >> S_SHIFT]    = BTRFS_FT_SYMLINK,
101 };
102 
103 static int btrfs_setsize(struct inode *inode, struct iattr *attr);
104 static int btrfs_truncate(struct inode *inode);
105 static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent);
106 static noinline int cow_file_range(struct inode *inode,
107                                    struct page *locked_page,
108                                    u64 start, u64 end, u64 delalloc_end,
109                                    int *page_started, unsigned long *nr_written,
110                                    int unlock, struct btrfs_dedupe_hash *hash);
111 static struct extent_map *create_io_em(struct inode *inode, u64 start, u64 len,
112                                        u64 orig_start, u64 block_start,
113                                        u64 block_len, u64 orig_block_len,
114                                        u64 ram_bytes, int compress_type,
115                                        int type);
116 
117 static void __endio_write_update_ordered(struct inode *inode,
118                                          const u64 offset, const u64 bytes,
119                                          const bool uptodate);
120 
121 /*
122  * Cleanup all submitted ordered extents in specified range to handle errors
123  * from the fill_dellaloc() callback.
124  *
125  * NOTE: caller must ensure that when an error happens, it can not call
126  * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING
127  * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata
128  * to be released, which we want to happen only when finishing the ordered
129  * extent (btrfs_finish_ordered_io()). Also note that the caller of the
130  * fill_delalloc() callback already does proper cleanup for the first page of
131  * the range, that is, it invokes the callback writepage_end_io_hook() for the
132  * range of the first page.
133  */
134 static inline void btrfs_cleanup_ordered_extents(struct inode *inode,
135                                                  const u64 offset,
136                                                  const u64 bytes)
137 {
138         unsigned long index = offset >> PAGE_SHIFT;
139         unsigned long end_index = (offset + bytes - 1) >> PAGE_SHIFT;
140         struct page *page;
141 
142         while (index <= end_index) {
143                 page = find_get_page(inode->i_mapping, index);
144                 index++;
145                 if (!page)
146                         continue;
147                 ClearPagePrivate2(page);
148                 put_page(page);
149         }
150         return __endio_write_update_ordered(inode, offset + PAGE_SIZE,
151                                             bytes - PAGE_SIZE, false);
152 }
153 
154 static int btrfs_dirty_inode(struct inode *inode);
155 
156 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
157 void btrfs_test_inode_set_ops(struct inode *inode)
158 {
159         BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
160 }
161 #endif
162 
163 static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
164                                      struct inode *inode,  struct inode *dir,
165                                      const struct qstr *qstr)
166 {
167         int err;
168 
169         err = btrfs_init_acl(trans, inode, dir);
170         if (!err)
171                 err = btrfs_xattr_security_init(trans, inode, dir, qstr);
172         return err;
173 }
174 
175 /*
176  * this does all the hard work for inserting an inline extent into
177  * the btree.  The caller should have done a btrfs_drop_extents so that
178  * no overlapping inline items exist in the btree
179  */
180 static int insert_inline_extent(struct btrfs_trans_handle *trans,
181                                 struct btrfs_path *path, int extent_inserted,
182                                 struct btrfs_root *root, struct inode *inode,
183                                 u64 start, size_t size, size_t compressed_size,
184                                 int compress_type,
185                                 struct page **compressed_pages)
186 {
187         struct extent_buffer *leaf;
188         struct page *page = NULL;
189         char *kaddr;
190         unsigned long ptr;
191         struct btrfs_file_extent_item *ei;
192         int ret;
193         size_t cur_size = size;
194         unsigned long offset;
195 
196         if (compressed_size && compressed_pages)
197                 cur_size = compressed_size;
198 
199         inode_add_bytes(inode, size);
200 
201         if (!extent_inserted) {
202                 struct btrfs_key key;
203                 size_t datasize;
204 
205                 key.objectid = btrfs_ino(BTRFS_I(inode));
206                 key.offset = start;
207                 key.type = BTRFS_EXTENT_DATA_KEY;
208 
209                 datasize = btrfs_file_extent_calc_inline_size(cur_size);
210                 path->leave_spinning = 1;
211                 ret = btrfs_insert_empty_item(trans, root, path, &key,
212                                               datasize);
213                 if (ret)
214                         goto fail;
215         }
216         leaf = path->nodes[0];
217         ei = btrfs_item_ptr(leaf, path->slots[0],
218                             struct btrfs_file_extent_item);
219         btrfs_set_file_extent_generation(leaf, ei, trans->transid);
220         btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
221         btrfs_set_file_extent_encryption(leaf, ei, 0);
222         btrfs_set_file_extent_other_encoding(leaf, ei, 0);
223         btrfs_set_file_extent_ram_bytes(leaf, ei, size);
224         ptr = btrfs_file_extent_inline_start(ei);
225 
226         if (compress_type != BTRFS_COMPRESS_NONE) {
227                 struct page *cpage;
228                 int i = 0;
229                 while (compressed_size > 0) {
230                         cpage = compressed_pages[i];
231                         cur_size = min_t(unsigned long, compressed_size,
232                                        PAGE_SIZE);
233 
234                         kaddr = kmap_atomic(cpage);
235                         write_extent_buffer(leaf, kaddr, ptr, cur_size);
236                         kunmap_atomic(kaddr);
237 
238                         i++;
239                         ptr += cur_size;
240                         compressed_size -= cur_size;
241                 }
242                 btrfs_set_file_extent_compression(leaf, ei,
243                                                   compress_type);
244         } else {
245                 page = find_get_page(inode->i_mapping,
246                                      start >> PAGE_SHIFT);
247                 btrfs_set_file_extent_compression(leaf, ei, 0);
248                 kaddr = kmap_atomic(page);
249                 offset = start & (PAGE_SIZE - 1);
250                 write_extent_buffer(leaf, kaddr + offset, ptr, size);
251                 kunmap_atomic(kaddr);
252                 put_page(page);
253         }
254         btrfs_mark_buffer_dirty(leaf);
255         btrfs_release_path(path);
256 
257         /*
258          * we're an inline extent, so nobody can
259          * extend the file past i_size without locking
260          * a page we already have locked.
261          *
262          * We must do any isize and inode updates
263          * before we unlock the pages.  Otherwise we
264          * could end up racing with unlink.
265          */
266         BTRFS_I(inode)->disk_i_size = inode->i_size;
267         ret = btrfs_update_inode(trans, root, inode);
268 
269 fail:
270         return ret;
271 }
272 
273 
274 /*
275  * conditionally insert an inline extent into the file.  This
276  * does the checks required to make sure the data is small enough
277  * to fit as an inline extent.
278  */
279 static noinline int cow_file_range_inline(struct btrfs_root *root,
280                                           struct inode *inode, u64 start,
281                                           u64 end, size_t compressed_size,
282                                           int compress_type,
283                                           struct page **compressed_pages)
284 {
285         struct btrfs_fs_info *fs_info = root->fs_info;
286         struct btrfs_trans_handle *trans;
287         u64 isize = i_size_read(inode);
288         u64 actual_end = min(end + 1, isize);
289         u64 inline_len = actual_end - start;
290         u64 aligned_end = ALIGN(end, fs_info->sectorsize);
291         u64 data_len = inline_len;
292         int ret;
293         struct btrfs_path *path;
294         int extent_inserted = 0;
295         u32 extent_item_size;
296 
297         if (compressed_size)
298                 data_len = compressed_size;
299 
300         if (start > 0 ||
301             actual_end > fs_info->sectorsize ||
302             data_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info) ||
303             (!compressed_size &&
304             (actual_end & (fs_info->sectorsize - 1)) == 0) ||
305             end + 1 < isize ||
306             data_len > fs_info->max_inline) {
307                 return 1;
308         }
309 
310         path = btrfs_alloc_path();
311         if (!path)
312                 return -ENOMEM;
313 
314         trans = btrfs_join_transaction(root);
315         if (IS_ERR(trans)) {
316                 btrfs_free_path(path);
317                 return PTR_ERR(trans);
318         }
319         trans->block_rsv = &fs_info->delalloc_block_rsv;
320 
321         if (compressed_size && compressed_pages)
322                 extent_item_size = btrfs_file_extent_calc_inline_size(
323                    compressed_size);
324         else
325                 extent_item_size = btrfs_file_extent_calc_inline_size(
326                     inline_len);
327 
328         ret = __btrfs_drop_extents(trans, root, inode, path,
329                                    start, aligned_end, NULL,
330                                    1, 1, extent_item_size, &extent_inserted);
331         if (ret) {
332                 btrfs_abort_transaction(trans, ret);
333                 goto out;
334         }
335 
336         if (isize > actual_end)
337                 inline_len = min_t(u64, isize, actual_end);
338         ret = insert_inline_extent(trans, path, extent_inserted,
339                                    root, inode, start,
340                                    inline_len, compressed_size,
341                                    compress_type, compressed_pages);
342         if (ret && ret != -ENOSPC) {
343                 btrfs_abort_transaction(trans, ret);
344                 goto out;
345         } else if (ret == -ENOSPC) {
346                 ret = 1;
347                 goto out;
348         }
349 
350         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(inode)->runtime_flags);
351         btrfs_delalloc_release_metadata(BTRFS_I(inode), end + 1 - start);
352         btrfs_drop_extent_cache(BTRFS_I(inode), start, aligned_end - 1, 0);
353 out:
354         /*
355          * Don't forget to free the reserved space, as for inlined extent
356          * it won't count as data extent, free them directly here.
357          * And at reserve time, it's always aligned to page size, so
358          * just free one page here.
359          */
360         btrfs_qgroup_free_data(inode, NULL, 0, PAGE_SIZE);
361         btrfs_free_path(path);
362         btrfs_end_transaction(trans);
363         return ret;
364 }
365 
366 struct async_extent {
367         u64 start;
368         u64 ram_size;
369         u64 compressed_size;
370         struct page **pages;
371         unsigned long nr_pages;
372         int compress_type;
373         struct list_head list;
374 };
375 
376 struct async_cow {
377         struct inode *inode;
378         struct btrfs_root *root;
379         struct page *locked_page;
380         u64 start;
381         u64 end;
382         struct list_head extents;
383         struct btrfs_work work;
384 };
385 
386 static noinline int add_async_extent(struct async_cow *cow,
387                                      u64 start, u64 ram_size,
388                                      u64 compressed_size,
389                                      struct page **pages,
390                                      unsigned long nr_pages,
391                                      int compress_type)
392 {
393         struct async_extent *async_extent;
394 
395         async_extent = kmalloc(sizeof(*async_extent), GFP_NOFS);
396         BUG_ON(!async_extent); /* -ENOMEM */
397         async_extent->start = start;
398         async_extent->ram_size = ram_size;
399         async_extent->compressed_size = compressed_size;
400         async_extent->pages = pages;
401         async_extent->nr_pages = nr_pages;
402         async_extent->compress_type = compress_type;
403         list_add_tail(&async_extent->list, &cow->extents);
404         return 0;
405 }
406 
407 static inline int inode_need_compress(struct inode *inode, u64 start, u64 end)
408 {
409         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
410 
411         /* force compress */
412         if (btrfs_test_opt(fs_info, FORCE_COMPRESS))
413                 return 1;
414         /* defrag ioctl */
415         if (BTRFS_I(inode)->defrag_compress)
416                 return 1;
417         /* bad compression ratios */
418         if (BTRFS_I(inode)->flags & BTRFS_INODE_NOCOMPRESS)
419                 return 0;
420         if (btrfs_test_opt(fs_info, COMPRESS) ||
421             BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS ||
422             BTRFS_I(inode)->prop_compress)
423                 return btrfs_compress_heuristic(inode, start, end);
424         return 0;
425 }
426 
427 static inline void inode_should_defrag(struct btrfs_inode *inode,
428                 u64 start, u64 end, u64 num_bytes, u64 small_write)
429 {
430         /* If this is a small write inside eof, kick off a defrag */
431         if (num_bytes < small_write &&
432             (start > 0 || end + 1 < inode->disk_i_size))
433                 btrfs_add_inode_defrag(NULL, inode);
434 }
435 
436 /*
437  * we create compressed extents in two phases.  The first
438  * phase compresses a range of pages that have already been
439  * locked (both pages and state bits are locked).
440  *
441  * This is done inside an ordered work queue, and the compression
442  * is spread across many cpus.  The actual IO submission is step
443  * two, and the ordered work queue takes care of making sure that
444  * happens in the same order things were put onto the queue by
445  * writepages and friends.
446  *
447  * If this code finds it can't get good compression, it puts an
448  * entry onto the work queue to write the uncompressed bytes.  This
449  * makes sure that both compressed inodes and uncompressed inodes
450  * are written in the same order that the flusher thread sent them
451  * down.
452  */
453 static noinline void compress_file_range(struct inode *inode,
454                                         struct page *locked_page,
455                                         u64 start, u64 end,
456                                         struct async_cow *async_cow,
457                                         int *num_added)
458 {
459         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
460         struct btrfs_root *root = BTRFS_I(inode)->root;
461         u64 num_bytes;
462         u64 blocksize = fs_info->sectorsize;
463         u64 actual_end;
464         u64 isize = i_size_read(inode);
465         int ret = 0;
466         struct page **pages = NULL;
467         unsigned long nr_pages;
468         unsigned long total_compressed = 0;
469         unsigned long total_in = 0;
470         int i;
471         int will_compress;
472         int compress_type = fs_info->compress_type;
473         int redirty = 0;
474 
475         inode_should_defrag(BTRFS_I(inode), start, end, end - start + 1,
476                         SZ_16K);
477 
478         actual_end = min_t(u64, isize, end + 1);
479 again:
480         will_compress = 0;
481         nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
482         BUILD_BUG_ON((BTRFS_MAX_COMPRESSED % PAGE_SIZE) != 0);
483         nr_pages = min_t(unsigned long, nr_pages,
484                         BTRFS_MAX_COMPRESSED / PAGE_SIZE);
485 
486         /*
487          * we don't want to send crud past the end of i_size through
488          * compression, that's just a waste of CPU time.  So, if the
489          * end of the file is before the start of our current
490          * requested range of bytes, we bail out to the uncompressed
491          * cleanup code that can deal with all of this.
492          *
493          * It isn't really the fastest way to fix things, but this is a
494          * very uncommon corner.
495          */
496         if (actual_end <= start)
497                 goto cleanup_and_bail_uncompressed;
498 
499         total_compressed = actual_end - start;
500 
501         /*
502          * skip compression for a small file range(<=blocksize) that
503          * isn't an inline extent, since it doesn't save disk space at all.
504          */
505         if (total_compressed <= blocksize &&
506            (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size))
507                 goto cleanup_and_bail_uncompressed;
508 
509         total_compressed = min_t(unsigned long, total_compressed,
510                         BTRFS_MAX_UNCOMPRESSED);
511         num_bytes = ALIGN(end - start + 1, blocksize);
512         num_bytes = max(blocksize,  num_bytes);
513         total_in = 0;
514         ret = 0;
515 
516         /*
517          * we do compression for mount -o compress and when the
518          * inode has not been flagged as nocompress.  This flag can
519          * change at any time if we discover bad compression ratios.
520          */
521         if (inode_need_compress(inode, start, end)) {
522                 WARN_ON(pages);
523                 pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
524                 if (!pages) {
525                         /* just bail out to the uncompressed code */
526                         goto cont;
527                 }
528 
529                 if (BTRFS_I(inode)->defrag_compress)
530                         compress_type = BTRFS_I(inode)->defrag_compress;
531                 else if (BTRFS_I(inode)->prop_compress)
532                         compress_type = BTRFS_I(inode)->prop_compress;
533 
534                 /*
535                  * we need to call clear_page_dirty_for_io on each
536                  * page in the range.  Otherwise applications with the file
537                  * mmap'd can wander in and change the page contents while
538                  * we are compressing them.
539                  *
540                  * If the compression fails for any reason, we set the pages
541                  * dirty again later on.
542                  */
543                 extent_range_clear_dirty_for_io(inode, start, end);
544                 redirty = 1;
545                 ret = btrfs_compress_pages(compress_type,
546                                            inode->i_mapping, start,
547                                            pages,
548                                            &nr_pages,
549                                            &total_in,
550                                            &total_compressed);
551 
552                 if (!ret) {
553                         unsigned long offset = total_compressed &
554                                 (PAGE_SIZE - 1);
555                         struct page *page = pages[nr_pages - 1];
556                         char *kaddr;
557 
558                         /* zero the tail end of the last page, we might be
559                          * sending it down to disk
560                          */
561                         if (offset) {
562                                 kaddr = kmap_atomic(page);
563                                 memset(kaddr + offset, 0,
564                                        PAGE_SIZE - offset);
565                                 kunmap_atomic(kaddr);
566                         }
567                         will_compress = 1;
568                 }
569         }
570 cont:
571         if (start == 0) {
572                 /* lets try to make an inline extent */
573                 if (ret || total_in < (actual_end - start)) {
574                         /* we didn't compress the entire range, try
575                          * to make an uncompressed inline extent.
576                          */
577                         ret = cow_file_range_inline(root, inode, start, end,
578                                             0, BTRFS_COMPRESS_NONE, NULL);
579                 } else {
580                         /* try making a compressed inline extent */
581                         ret = cow_file_range_inline(root, inode, start, end,
582                                                     total_compressed,
583                                                     compress_type, pages);
584                 }
585                 if (ret <= 0) {
586                         unsigned long clear_flags = EXTENT_DELALLOC |
587                                 EXTENT_DELALLOC_NEW | EXTENT_DEFRAG;
588                         unsigned long page_error_op;
589 
590                         clear_flags |= (ret < 0) ? EXTENT_DO_ACCOUNTING : 0;
591                         page_error_op = ret < 0 ? PAGE_SET_ERROR : 0;
592 
593                         /*
594                          * inline extent creation worked or returned error,
595                          * we don't need to create any more async work items.
596                          * Unlock and free up our temp pages.
597                          */
598                         extent_clear_unlock_delalloc(inode, start, end, end,
599                                                      NULL, clear_flags,
600                                                      PAGE_UNLOCK |
601                                                      PAGE_CLEAR_DIRTY |
602                                                      PAGE_SET_WRITEBACK |
603                                                      page_error_op |
604                                                      PAGE_END_WRITEBACK);
605                         if (ret == 0)
606                                 btrfs_free_reserved_data_space_noquota(inode,
607                                                                start,
608                                                                end - start + 1);
609                         goto free_pages_out;
610                 }
611         }
612 
613         if (will_compress) {
614                 /*
615                  * we aren't doing an inline extent round the compressed size
616                  * up to a block size boundary so the allocator does sane
617                  * things
618                  */
619                 total_compressed = ALIGN(total_compressed, blocksize);
620 
621                 /*
622                  * one last check to make sure the compression is really a
623                  * win, compare the page count read with the blocks on disk,
624                  * compression must free at least one sector size
625                  */
626                 total_in = ALIGN(total_in, PAGE_SIZE);
627                 if (total_compressed + blocksize <= total_in) {
628                         num_bytes = total_in;
629                         *num_added += 1;
630 
631                         /*
632                          * The async work queues will take care of doing actual
633                          * allocation on disk for these compressed pages, and
634                          * will submit them to the elevator.
635                          */
636                         add_async_extent(async_cow, start, num_bytes,
637                                         total_compressed, pages, nr_pages,
638                                         compress_type);
639 
640                         if (start + num_bytes < end) {
641                                 start += num_bytes;
642                                 pages = NULL;
643                                 cond_resched();
644                                 goto again;
645                         }
646                         return;
647                 }
648         }
649         if (pages) {
650                 /*
651                  * the compression code ran but failed to make things smaller,
652                  * free any pages it allocated and our page pointer array
653                  */
654                 for (i = 0; i < nr_pages; i++) {
655                         WARN_ON(pages[i]->mapping);
656                         put_page(pages[i]);
657                 }
658                 kfree(pages);
659                 pages = NULL;
660                 total_compressed = 0;
661                 nr_pages = 0;
662 
663                 /* flag the file so we don't compress in the future */
664                 if (!btrfs_test_opt(fs_info, FORCE_COMPRESS) &&
665                     !(BTRFS_I(inode)->prop_compress)) {
666                         BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
667                 }
668         }
669 cleanup_and_bail_uncompressed:
670         /*
671          * No compression, but we still need to write the pages in the file
672          * we've been given so far.  redirty the locked page if it corresponds
673          * to our extent and set things up for the async work queue to run
674          * cow_file_range to do the normal delalloc dance.
675          */
676         if (page_offset(locked_page) >= start &&
677             page_offset(locked_page) <= end)
678                 __set_page_dirty_nobuffers(locked_page);
679                 /* unlocked later on in the async handlers */
680 
681         if (redirty)
682                 extent_range_redirty_for_io(inode, start, end);
683         add_async_extent(async_cow, start, end - start + 1, 0, NULL, 0,
684                          BTRFS_COMPRESS_NONE);
685         *num_added += 1;
686 
687         return;
688 
689 free_pages_out:
690         for (i = 0; i < nr_pages; i++) {
691                 WARN_ON(pages[i]->mapping);
692                 put_page(pages[i]);
693         }
694         kfree(pages);
695 }
696 
697 static void free_async_extent_pages(struct async_extent *async_extent)
698 {
699         int i;
700 
701         if (!async_extent->pages)
702                 return;
703 
704         for (i = 0; i < async_extent->nr_pages; i++) {
705                 WARN_ON(async_extent->pages[i]->mapping);
706                 put_page(async_extent->pages[i]);
707         }
708         kfree(async_extent->pages);
709         async_extent->nr_pages = 0;
710         async_extent->pages = NULL;
711 }
712 
713 /*
714  * phase two of compressed writeback.  This is the ordered portion
715  * of the code, which only gets called in the order the work was
716  * queued.  We walk all the async extents created by compress_file_range
717  * and send them down to the disk.
718  */
719 static noinline void submit_compressed_extents(struct inode *inode,
720                                               struct async_cow *async_cow)
721 {
722         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
723         struct async_extent *async_extent;
724         u64 alloc_hint = 0;
725         struct btrfs_key ins;
726         struct extent_map *em;
727         struct btrfs_root *root = BTRFS_I(inode)->root;
728         struct extent_io_tree *io_tree;
729         int ret = 0;
730 
731 again:
732         while (!list_empty(&async_cow->extents)) {
733                 async_extent = list_entry(async_cow->extents.next,
734                                           struct async_extent, list);
735                 list_del(&async_extent->list);
736 
737                 io_tree = &BTRFS_I(inode)->io_tree;
738 
739 retry:
740                 /* did the compression code fall back to uncompressed IO? */
741                 if (!async_extent->pages) {
742                         int page_started = 0;
743                         unsigned long nr_written = 0;
744 
745                         lock_extent(io_tree, async_extent->start,
746                                          async_extent->start +
747                                          async_extent->ram_size - 1);
748 
749                         /* allocate blocks */
750                         ret = cow_file_range(inode, async_cow->locked_page,
751                                              async_extent->start,
752                                              async_extent->start +
753                                              async_extent->ram_size - 1,
754                                              async_extent->start +
755                                              async_extent->ram_size - 1,
756                                              &page_started, &nr_written, 0,
757                                              NULL);
758 
759                         /* JDM XXX */
760 
761                         /*
762                          * if page_started, cow_file_range inserted an
763                          * inline extent and took care of all the unlocking
764                          * and IO for us.  Otherwise, we need to submit
765                          * all those pages down to the drive.
766                          */
767                         if (!page_started && !ret)
768                                 extent_write_locked_range(io_tree,
769                                                   inode, async_extent->start,
770                                                   async_extent->start +
771                                                   async_extent->ram_size - 1,
772                                                   btrfs_get_extent,
773                                                   WB_SYNC_ALL);
774                         else if (ret)
775                                 unlock_page(async_cow->locked_page);
776                         kfree(async_extent);
777                         cond_resched();
778                         continue;
779                 }
780 
781                 lock_extent(io_tree, async_extent->start,
782                             async_extent->start + async_extent->ram_size - 1);
783 
784                 ret = btrfs_reserve_extent(root, async_extent->ram_size,
785                                            async_extent->compressed_size,
786                                            async_extent->compressed_size,
787                                            0, alloc_hint, &ins, 1, 1);
788                 if (ret) {
789                         free_async_extent_pages(async_extent);
790 
791                         if (ret == -ENOSPC) {
792                                 unlock_extent(io_tree, async_extent->start,
793                                               async_extent->start +
794                                               async_extent->ram_size - 1);
795 
796                                 /*
797                                  * we need to redirty the pages if we decide to
798                                  * fallback to uncompressed IO, otherwise we
799                                  * will not submit these pages down to lower
800                                  * layers.
801                                  */
802                                 extent_range_redirty_for_io(inode,
803                                                 async_extent->start,
804                                                 async_extent->start +
805                                                 async_extent->ram_size - 1);
806 
807                                 goto retry;
808                         }
809                         goto out_free;
810                 }
811                 /*
812                  * here we're doing allocation and writeback of the
813                  * compressed pages
814                  */
815                 em = create_io_em(inode, async_extent->start,
816                                   async_extent->ram_size, /* len */
817                                   async_extent->start, /* orig_start */
818                                   ins.objectid, /* block_start */
819                                   ins.offset, /* block_len */
820                                   ins.offset, /* orig_block_len */
821                                   async_extent->ram_size, /* ram_bytes */
822                                   async_extent->compress_type,
823                                   BTRFS_ORDERED_COMPRESSED);
824                 if (IS_ERR(em))
825                         /* ret value is not necessary due to void function */
826                         goto out_free_reserve;
827                 free_extent_map(em);
828 
829                 ret = btrfs_add_ordered_extent_compress(inode,
830                                                 async_extent->start,
831                                                 ins.objectid,
832                                                 async_extent->ram_size,
833                                                 ins.offset,
834                                                 BTRFS_ORDERED_COMPRESSED,
835                                                 async_extent->compress_type);
836                 if (ret) {
837                         btrfs_drop_extent_cache(BTRFS_I(inode),
838                                                 async_extent->start,
839                                                 async_extent->start +
840                                                 async_extent->ram_size - 1, 0);
841                         goto out_free_reserve;
842                 }
843                 btrfs_dec_block_group_reservations(fs_info, ins.objectid);
844 
845                 /*
846                  * clear dirty, set writeback and unlock the pages.
847                  */
848                 extent_clear_unlock_delalloc(inode, async_extent->start,
849                                 async_extent->start +
850                                 async_extent->ram_size - 1,
851                                 async_extent->start +
852                                 async_extent->ram_size - 1,
853                                 NULL, EXTENT_LOCKED | EXTENT_DELALLOC,
854                                 PAGE_UNLOCK | PAGE_CLEAR_DIRTY |
855                                 PAGE_SET_WRITEBACK);
856                 if (btrfs_submit_compressed_write(inode,
857                                     async_extent->start,
858                                     async_extent->ram_size,
859                                     ins.objectid,
860                                     ins.offset, async_extent->pages,
861                                     async_extent->nr_pages)) {
862                         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
863                         struct page *p = async_extent->pages[0];
864                         const u64 start = async_extent->start;
865                         const u64 end = start + async_extent->ram_size - 1;
866 
867                         p->mapping = inode->i_mapping;
868                         tree->ops->writepage_end_io_hook(p, start, end,
869                                                          NULL, 0);
870                         p->mapping = NULL;
871                         extent_clear_unlock_delalloc(inode, start, end, end,
872                                                      NULL, 0,
873                                                      PAGE_END_WRITEBACK |
874                                                      PAGE_SET_ERROR);
875                         free_async_extent_pages(async_extent);
876                 }
877                 alloc_hint = ins.objectid + ins.offset;
878                 kfree(async_extent);
879                 cond_resched();
880         }
881         return;
882 out_free_reserve:
883         btrfs_dec_block_group_reservations(fs_info, ins.objectid);
884         btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
885 out_free:
886         extent_clear_unlock_delalloc(inode, async_extent->start,
887                                      async_extent->start +
888                                      async_extent->ram_size - 1,
889                                      async_extent->start +
890                                      async_extent->ram_size - 1,
891                                      NULL, EXTENT_LOCKED | EXTENT_DELALLOC |
892                                      EXTENT_DELALLOC_NEW |
893                                      EXTENT_DEFRAG | EXTENT_DO_ACCOUNTING,
894                                      PAGE_UNLOCK | PAGE_CLEAR_DIRTY |
895                                      PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK |
896                                      PAGE_SET_ERROR);
897         free_async_extent_pages(async_extent);
898         kfree(async_extent);
899         goto again;
900 }
901 
902 static u64 get_extent_allocation_hint(struct inode *inode, u64 start,
903                                       u64 num_bytes)
904 {
905         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
906         struct extent_map *em;
907         u64 alloc_hint = 0;
908 
909         read_lock(&em_tree->lock);
910         em = search_extent_mapping(em_tree, start, num_bytes);
911         if (em) {
912                 /*
913                  * if block start isn't an actual block number then find the
914                  * first block in this inode and use that as a hint.  If that
915                  * block is also bogus then just don't worry about it.
916                  */
917                 if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
918                         free_extent_map(em);
919                         em = search_extent_mapping(em_tree, 0, 0);
920                         if (em && em->block_start < EXTENT_MAP_LAST_BYTE)
921                                 alloc_hint = em->block_start;
922                         if (em)
923                                 free_extent_map(em);
924                 } else {
925                         alloc_hint = em->block_start;
926                         free_extent_map(em);
927                 }
928         }
929         read_unlock(&em_tree->lock);
930 
931         return alloc_hint;
932 }
933 
934 /*
935  * when extent_io.c finds a delayed allocation range in the file,
936  * the call backs end up in this code.  The basic idea is to
937  * allocate extents on disk for the range, and create ordered data structs
938  * in ram to track those extents.
939  *
940  * locked_page is the page that writepage had locked already.  We use
941  * it to make sure we don't do extra locks or unlocks.
942  *
943  * *page_started is set to one if we unlock locked_page and do everything
944  * required to start IO on it.  It may be clean and already done with
945  * IO when we return.
946  */
947 static noinline int cow_file_range(struct inode *inode,
948                                    struct page *locked_page,
949                                    u64 start, u64 end, u64 delalloc_end,
950                                    int *page_started, unsigned long *nr_written,
951                                    int unlock, struct btrfs_dedupe_hash *hash)
952 {
953         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
954         struct btrfs_root *root = BTRFS_I(inode)->root;
955         u64 alloc_hint = 0;
956         u64 num_bytes;
957         unsigned long ram_size;
958         u64 disk_num_bytes;
959         u64 cur_alloc_size = 0;
960         u64 blocksize = fs_info->sectorsize;
961         struct btrfs_key ins;
962         struct extent_map *em;
963         unsigned clear_bits;
964         unsigned long page_ops;
965         bool extent_reserved = false;
966         int ret = 0;
967 
968         if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
969                 WARN_ON_ONCE(1);
970                 ret = -EINVAL;
971                 goto out_unlock;
972         }
973 
974         num_bytes = ALIGN(end - start + 1, blocksize);
975         num_bytes = max(blocksize,  num_bytes);
976         disk_num_bytes = num_bytes;
977 
978         inode_should_defrag(BTRFS_I(inode), start, end, num_bytes, SZ_64K);
979 
980         if (start == 0) {
981                 /* lets try to make an inline extent */
982                 ret = cow_file_range_inline(root, inode, start, end, 0,
983                                         BTRFS_COMPRESS_NONE, NULL);
984                 if (ret == 0) {
985                         extent_clear_unlock_delalloc(inode, start, end,
986                                      delalloc_end, NULL,
987                                      EXTENT_LOCKED | EXTENT_DELALLOC |
988                                      EXTENT_DELALLOC_NEW |
989                                      EXTENT_DEFRAG, PAGE_UNLOCK |
990                                      PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK |
991                                      PAGE_END_WRITEBACK);
992                         btrfs_free_reserved_data_space_noquota(inode, start,
993                                                 end - start + 1);
994                         *nr_written = *nr_written +
995                              (end - start + PAGE_SIZE) / PAGE_SIZE;
996                         *page_started = 1;
997                         goto out;
998                 } else if (ret < 0) {
999                         goto out_unlock;
1000                 }
1001         }
1002 
1003         BUG_ON(disk_num_bytes >
1004                btrfs_super_total_bytes(fs_info->super_copy));
1005 
1006         alloc_hint = get_extent_allocation_hint(inode, start, num_bytes);
1007         btrfs_drop_extent_cache(BTRFS_I(inode), start,
1008                         start + num_bytes - 1, 0);
1009 
1010         while (disk_num_bytes > 0) {
1011                 cur_alloc_size = disk_num_bytes;
1012                 ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,
1013                                            fs_info->sectorsize, 0, alloc_hint,
1014                                            &ins, 1, 1);
1015                 if (ret < 0)
1016                         goto out_unlock;
1017                 cur_alloc_size = ins.offset;
1018                 extent_reserved = true;
1019 
1020                 ram_size = ins.offset;
1021                 em = create_io_em(inode, start, ins.offset, /* len */
1022                                   start, /* orig_start */
1023                                   ins.objectid, /* block_start */
1024                                   ins.offset, /* block_len */
1025                                   ins.offset, /* orig_block_len */
1026                                   ram_size, /* ram_bytes */
1027                                   BTRFS_COMPRESS_NONE, /* compress_type */
1028                                   BTRFS_ORDERED_REGULAR /* type */);
1029                 if (IS_ERR(em))
1030                         goto out_reserve;
1031                 free_extent_map(em);
1032 
1033                 ret = btrfs_add_ordered_extent(inode, start, ins.objectid,
1034                                                ram_size, cur_alloc_size, 0);
1035                 if (ret)
1036                         goto out_drop_extent_cache;
1037 
1038                 if (root->root_key.objectid ==
1039                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
1040                         ret = btrfs_reloc_clone_csums(inode, start,
1041                                                       cur_alloc_size);
1042                         /*
1043                          * Only drop cache here, and process as normal.
1044                          *
1045                          * We must not allow extent_clear_unlock_delalloc()
1046                          * at out_unlock label to free meta of this ordered
1047                          * extent, as its meta should be freed by
1048                          * btrfs_finish_ordered_io().
1049                          *
1050                          * So we must continue until @start is increased to
1051                          * skip current ordered extent.
1052                          */
1053                         if (ret)
1054                                 btrfs_drop_extent_cache(BTRFS_I(inode), start,
1055                                                 start + ram_size - 1, 0);
1056                 }
1057 
1058                 btrfs_dec_block_group_reservations(fs_info, ins.objectid);
1059 
1060                 /* we're not doing compressed IO, don't unlock the first
1061                  * page (which the caller expects to stay locked), don't
1062                  * clear any dirty bits and don't set any writeback bits
1063                  *
1064                  * Do set the Private2 bit so we know this page was properly
1065                  * setup for writepage
1066                  */
1067                 page_ops = unlock ? PAGE_UNLOCK : 0;
1068                 page_ops |= PAGE_SET_PRIVATE2;
1069 
1070                 extent_clear_unlock_delalloc(inode, start,
1071                                              start + ram_size - 1,
1072                                              delalloc_end, locked_page,
1073                                              EXTENT_LOCKED | EXTENT_DELALLOC,
1074                                              page_ops);
1075                 if (disk_num_bytes < cur_alloc_size)
1076                         disk_num_bytes = 0;
1077                 else
1078                         disk_num_bytes -= cur_alloc_size;
1079                 num_bytes -= cur_alloc_size;
1080                 alloc_hint = ins.objectid + ins.offset;
1081                 start += cur_alloc_size;
1082                 extent_reserved = false;
1083 
1084                 /*
1085                  * btrfs_reloc_clone_csums() error, since start is increased
1086                  * extent_clear_unlock_delalloc() at out_unlock label won't
1087                  * free metadata of current ordered extent, we're OK to exit.
1088                  */
1089                 if (ret)
1090                         goto out_unlock;
1091         }
1092 out:
1093         return ret;
1094 
1095 out_drop_extent_cache:
1096         btrfs_drop_extent_cache(BTRFS_I(inode), start, start + ram_size - 1, 0);
1097 out_reserve:
1098         btrfs_dec_block_group_reservations(fs_info, ins.objectid);
1099         btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
1100 out_unlock:
1101         clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
1102                 EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV;
1103         page_ops = PAGE_UNLOCK | PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK |
1104                 PAGE_END_WRITEBACK;
1105         /*
1106          * If we reserved an extent for our delalloc range (or a subrange) and
1107          * failed to create the respective ordered extent, then it means that
1108          * when we reserved the extent we decremented the extent's size from
1109          * the data space_info's bytes_may_use counter and incremented the
1110          * space_info's bytes_reserved counter by the same amount. We must make
1111          * sure extent_clear_unlock_delalloc() does not try to decrement again
1112          * the data space_info's bytes_may_use counter, therefore we do not pass
1113          * it the flag EXTENT_CLEAR_DATA_RESV.
1114          */
1115         if (extent_reserved) {
1116                 extent_clear_unlock_delalloc(inode, start,
1117                                              start + cur_alloc_size,
1118                                              start + cur_alloc_size,
1119                                              locked_page,
1120                                              clear_bits,
1121                                              page_ops);
1122                 start += cur_alloc_size;
1123                 if (start >= end)
1124                         goto out;
1125         }
1126         extent_clear_unlock_delalloc(inode, start, end, delalloc_end,
1127                                      locked_page,
1128                                      clear_bits | EXTENT_CLEAR_DATA_RESV,
1129                                      page_ops);
1130         goto out;
1131 }
1132 
1133 /*
1134  * work queue call back to started compression on a file and pages
1135  */
1136 static noinline void async_cow_start(struct btrfs_work *work)
1137 {
1138         struct async_cow *async_cow;
1139         int num_added = 0;
1140         async_cow = container_of(work, struct async_cow, work);
1141 
1142         compress_file_range(async_cow->inode, async_cow->locked_page,
1143                             async_cow->start, async_cow->end, async_cow,
1144                             &num_added);
1145         if (num_added == 0) {
1146                 btrfs_add_delayed_iput(async_cow->inode);
1147                 async_cow->inode = NULL;
1148         }
1149 }
1150 
1151 /*
1152  * work queue call back to submit previously compressed pages
1153  */
1154 static noinline void async_cow_submit(struct btrfs_work *work)
1155 {
1156         struct btrfs_fs_info *fs_info;
1157         struct async_cow *async_cow;
1158         struct btrfs_root *root;
1159         unsigned long nr_pages;
1160 
1161         async_cow = container_of(work, struct async_cow, work);
1162 
1163         root = async_cow->root;
1164         fs_info = root->fs_info;
1165         nr_pages = (async_cow->end - async_cow->start + PAGE_SIZE) >>
1166                 PAGE_SHIFT;
1167 
1168         /*
1169          * atomic_sub_return implies a barrier for waitqueue_active
1170          */
1171         if (atomic_sub_return(nr_pages, &fs_info->async_delalloc_pages) <
1172             5 * SZ_1M &&
1173             waitqueue_active(&fs_info->async_submit_wait))
1174                 wake_up(&fs_info->async_submit_wait);
1175 
1176         if (async_cow->inode)
1177                 submit_compressed_extents(async_cow->inode, async_cow);
1178 }
1179 
1180 static noinline void async_cow_free(struct btrfs_work *work)
1181 {
1182         struct async_cow *async_cow;
1183         async_cow = container_of(work, struct async_cow, work);
1184         if (async_cow->inode)
1185                 btrfs_add_delayed_iput(async_cow->inode);
1186         kfree(async_cow);
1187 }
1188 
1189 static int cow_file_range_async(struct inode *inode, struct page *locked_page,
1190                                 u64 start, u64 end, int *page_started,
1191                                 unsigned long *nr_written)
1192 {
1193         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1194         struct async_cow *async_cow;
1195         struct btrfs_root *root = BTRFS_I(inode)->root;
1196         unsigned long nr_pages;
1197         u64 cur_end;
1198 
1199         clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, EXTENT_LOCKED,
1200                          1, 0, NULL, GFP_NOFS);
1201         while (start < end) {
1202                 async_cow = kmalloc(sizeof(*async_cow), GFP_NOFS);
1203                 BUG_ON(!async_cow); /* -ENOMEM */
1204                 async_cow->inode = igrab(inode);
1205                 async_cow->root = root;
1206                 async_cow->locked_page = locked_page;
1207                 async_cow->start = start;
1208 
1209                 if (BTRFS_I(inode)->flags & BTRFS_INODE_NOCOMPRESS &&
1210                     !btrfs_test_opt(fs_info, FORCE_COMPRESS))
1211                         cur_end = end;
1212                 else
1213                         cur_end = min(end, start + SZ_512K - 1);
1214 
1215                 async_cow->end = cur_end;
1216                 INIT_LIST_HEAD(&async_cow->extents);
1217 
1218                 btrfs_init_work(&async_cow->work,
1219                                 btrfs_delalloc_helper,
1220                                 async_cow_start, async_cow_submit,
1221                                 async_cow_free);
1222 
1223                 nr_pages = (cur_end - start + PAGE_SIZE) >>
1224                         PAGE_SHIFT;
1225                 atomic_add(nr_pages, &fs_info->async_delalloc_pages);
1226 
1227                 btrfs_queue_work(fs_info->delalloc_workers, &async_cow->work);
1228 
1229                 while (atomic_read(&fs_info->async_submit_draining) &&
1230                        atomic_read(&fs_info->async_delalloc_pages)) {
1231                         wait_event(fs_info->async_submit_wait,
1232                                    (atomic_read(&fs_info->async_delalloc_pages) ==
1233                                     0));
1234                 }
1235 
1236                 *nr_written += nr_pages;
1237                 start = cur_end + 1;
1238         }
1239         *page_started = 1;
1240         return 0;
1241 }
1242 
1243 static noinline int csum_exist_in_range(struct btrfs_fs_info *fs_info,
1244                                         u64 bytenr, u64 num_bytes)
1245 {
1246         int ret;
1247         struct btrfs_ordered_sum *sums;
1248         LIST_HEAD(list);
1249 
1250         ret = btrfs_lookup_csums_range(fs_info->csum_root, bytenr,
1251                                        bytenr + num_bytes - 1, &list, 0);
1252         if (ret == 0 && list_empty(&list))
1253                 return 0;
1254 
1255         while (!list_empty(&list)) {
1256                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
1257                 list_del(&sums->list);
1258                 kfree(sums);
1259         }
1260         return 1;
1261 }
1262 
1263 /*
1264  * when nowcow writeback call back.  This checks for snapshots or COW copies
1265  * of the extents that exist in the file, and COWs the file as required.
1266  *
1267  * If no cow copies or snapshots exist, we write directly to the existing
1268  * blocks on disk
1269  */
1270 static noinline int run_delalloc_nocow(struct inode *inode,
1271                                        struct page *locked_page,
1272                               u64 start, u64 end, int *page_started, int force,
1273                               unsigned long *nr_written)
1274 {
1275         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1276         struct btrfs_root *root = BTRFS_I(inode)->root;
1277         struct extent_buffer *leaf;
1278         struct btrfs_path *path;
1279         struct btrfs_file_extent_item *fi;
1280         struct btrfs_key found_key;
1281         struct extent_map *em;
1282         u64 cow_start;
1283         u64 cur_offset;
1284         u64 extent_end;
1285         u64 extent_offset;
1286         u64 disk_bytenr;
1287         u64 num_bytes;
1288         u64 disk_num_bytes;
1289         u64 ram_bytes;
1290         int extent_type;
1291         int ret, err;
1292         int type;
1293         int nocow;
1294         int check_prev = 1;
1295         bool nolock;
1296         u64 ino = btrfs_ino(BTRFS_I(inode));
1297 
1298         path = btrfs_alloc_path();
1299         if (!path) {
1300                 extent_clear_unlock_delalloc(inode, start, end, end,
1301                                              locked_page,
1302                                              EXTENT_LOCKED | EXTENT_DELALLOC |
1303                                              EXTENT_DO_ACCOUNTING |
1304                                              EXTENT_DEFRAG, PAGE_UNLOCK |
1305                                              PAGE_CLEAR_DIRTY |
1306                                              PAGE_SET_WRITEBACK |
1307                                              PAGE_END_WRITEBACK);
1308                 return -ENOMEM;
1309         }
1310 
1311         nolock = btrfs_is_free_space_inode(BTRFS_I(inode));
1312 
1313         cow_start = (u64)-1;
1314         cur_offset = start;
1315         while (1) {
1316                 ret = btrfs_lookup_file_extent(NULL, root, path, ino,
1317                                                cur_offset, 0);
1318                 if (ret < 0)
1319                         goto error;
1320                 if (ret > 0 && path->slots[0] > 0 && check_prev) {
1321                         leaf = path->nodes[0];
1322                         btrfs_item_key_to_cpu(leaf, &found_key,
1323                                               path->slots[0] - 1);
1324                         if (found_key.objectid == ino &&
1325                             found_key.type == BTRFS_EXTENT_DATA_KEY)
1326                                 path->slots[0]--;
1327                 }
1328                 check_prev = 0;
1329 next_slot:
1330                 leaf = path->nodes[0];
1331                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
1332                         ret = btrfs_next_leaf(root, path);
1333                         if (ret < 0)
1334                                 goto error;
1335                         if (ret > 0)
1336                                 break;
1337                         leaf = path->nodes[0];
1338                 }
1339 
1340                 nocow = 0;
1341                 disk_bytenr = 0;
1342                 num_bytes = 0;
1343                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1344 
1345                 if (found_key.objectid > ino)
1346                         break;
1347                 if (WARN_ON_ONCE(found_key.objectid < ino) ||
1348                     found_key.type < BTRFS_EXTENT_DATA_KEY) {
1349                         path->slots[0]++;
1350                         goto next_slot;
1351                 }
1352                 if (found_key.type > BTRFS_EXTENT_DATA_KEY ||
1353                     found_key.offset > end)
1354                         break;
1355 
1356                 if (found_key.offset > cur_offset) {
1357                         extent_end = found_key.offset;
1358                         extent_type = 0;
1359                         goto out_check;
1360                 }
1361 
1362                 fi = btrfs_item_ptr(leaf, path->slots[0],
1363                                     struct btrfs_file_extent_item);
1364                 extent_type = btrfs_file_extent_type(leaf, fi);
1365 
1366                 ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
1367                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
1368                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
1369                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1370                         extent_offset = btrfs_file_extent_offset(leaf, fi);
1371                         extent_end = found_key.offset +
1372                                 btrfs_file_extent_num_bytes(leaf, fi);
1373                         disk_num_bytes =
1374                                 btrfs_file_extent_disk_num_bytes(leaf, fi);
1375                         if (extent_end <= start) {
1376                                 path->slots[0]++;
1377                                 goto next_slot;
1378                         }
1379                         if (disk_bytenr == 0)
1380                                 goto out_check;
1381                         if (btrfs_file_extent_compression(leaf, fi) ||
1382                             btrfs_file_extent_encryption(leaf, fi) ||
1383                             btrfs_file_extent_other_encoding(leaf, fi))
1384                                 goto out_check;
1385                         if (extent_type == BTRFS_FILE_EXTENT_REG && !force)
1386                                 goto out_check;
1387                         if (btrfs_extent_readonly(fs_info, disk_bytenr))
1388                                 goto out_check;
1389                         if (btrfs_cross_ref_exist(root, ino,
1390                                                   found_key.offset -
1391                                                   extent_offset, disk_bytenr))
1392                                 goto out_check;
1393                         disk_bytenr += extent_offset;
1394                         disk_bytenr += cur_offset - found_key.offset;
1395                         num_bytes = min(end + 1, extent_end) - cur_offset;
1396                         /*
1397                          * if there are pending snapshots for this root,
1398                          * we fall into common COW way.
1399                          */
1400                         if (!nolock) {
1401                                 err = btrfs_start_write_no_snapshotting(root);
1402                                 if (!err)
1403                                         goto out_check;
1404                         }
1405                         /*
1406                          * force cow if csum exists in the range.
1407                          * this ensure that csum for a given extent are
1408                          * either valid or do not exist.
1409                          */
1410                         if (csum_exist_in_range(fs_info, disk_bytenr,
1411                                                 num_bytes)) {
1412                                 if (!nolock)
1413                                         btrfs_end_write_no_snapshotting(root);
1414                                 goto out_check;
1415                         }
1416                         if (!btrfs_inc_nocow_writers(fs_info, disk_bytenr)) {
1417                                 if (!nolock)
1418                                         btrfs_end_write_no_snapshotting(root);
1419                                 goto out_check;
1420                         }
1421                         nocow = 1;
1422                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
1423                         extent_end = found_key.offset +
1424                                 btrfs_file_extent_inline_len(leaf,
1425                                                      path->slots[0], fi);
1426                         extent_end = ALIGN(extent_end,
1427                                            fs_info->sectorsize);
1428                 } else {
1429                         BUG_ON(1);
1430                 }
1431 out_check:
1432                 if (extent_end <= start) {
1433                         path->slots[0]++;
1434                         if (!nolock && nocow)
1435                                 btrfs_end_write_no_snapshotting(root);
1436                         if (nocow)
1437                                 btrfs_dec_nocow_writers(fs_info, disk_bytenr);
1438                         goto next_slot;
1439                 }
1440                 if (!nocow) {
1441                         if (cow_start == (u64)-1)
1442                                 cow_start = cur_offset;
1443                         cur_offset = extent_end;
1444                         if (cur_offset > end)
1445                                 break;
1446                         path->slots[0]++;
1447                         goto next_slot;
1448                 }
1449 
1450                 btrfs_release_path(path);
1451                 if (cow_start != (u64)-1) {
1452                         ret = cow_file_range(inode, locked_page,
1453                                              cow_start, found_key.offset - 1,
1454                                              end, page_started, nr_written, 1,
1455                                              NULL);
1456                         if (ret) {
1457                                 if (!nolock && nocow)
1458                                         btrfs_end_write_no_snapshotting(root);
1459                                 if (nocow)
1460                                         btrfs_dec_nocow_writers(fs_info,
1461                                                                 disk_bytenr);
1462                                 goto error;
1463                         }
1464                         cow_start = (u64)-1;
1465                 }
1466 
1467                 if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
1468                         u64 orig_start = found_key.offset - extent_offset;
1469 
1470                         em = create_io_em(inode, cur_offset, num_bytes,
1471                                           orig_start,
1472                                           disk_bytenr, /* block_start */
1473                                           num_bytes, /* block_len */
1474                                           disk_num_bytes, /* orig_block_len */
1475                                           ram_bytes, BTRFS_COMPRESS_NONE,
1476                                           BTRFS_ORDERED_PREALLOC);
1477                         if (IS_ERR(em)) {
1478                                 if (!nolock && nocow)
1479                                         btrfs_end_write_no_snapshotting(root);
1480                                 if (nocow)
1481                                         btrfs_dec_nocow_writers(fs_info,
1482                                                                 disk_bytenr);
1483                                 ret = PTR_ERR(em);
1484                                 goto error;
1485                         }
1486                         free_extent_map(em);
1487                 }
1488 
1489                 if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
1490                         type = BTRFS_ORDERED_PREALLOC;
1491                 } else {
1492                         type = BTRFS_ORDERED_NOCOW;
1493                 }
1494 
1495                 ret = btrfs_add_ordered_extent(inode, cur_offset, disk_bytenr,
1496                                                num_bytes, num_bytes, type);
1497                 if (nocow)
1498                         btrfs_dec_nocow_writers(fs_info, disk_bytenr);
1499                 BUG_ON(ret); /* -ENOMEM */
1500 
1501                 if (root->root_key.objectid ==
1502                     BTRFS_DATA_RELOC_TREE_OBJECTID)
1503                         /*
1504                          * Error handled later, as we must prevent
1505                          * extent_clear_unlock_delalloc() in error handler
1506                          * from freeing metadata of created ordered extent.
1507                          */
1508                         ret = btrfs_reloc_clone_csums(inode, cur_offset,
1509                                                       num_bytes);
1510 
1511                 extent_clear_unlock_delalloc(inode, cur_offset,
1512                                              cur_offset + num_bytes - 1, end,
1513                                              locked_page, EXTENT_LOCKED |
1514                                              EXTENT_DELALLOC |
1515                                              EXTENT_CLEAR_DATA_RESV,
1516                                              PAGE_UNLOCK | PAGE_SET_PRIVATE2);
1517 
1518                 if (!nolock && nocow)
1519                         btrfs_end_write_no_snapshotting(root);
1520                 cur_offset = extent_end;
1521 
1522                 /*
1523                  * btrfs_reloc_clone_csums() error, now we're OK to call error
1524                  * handler, as metadata for created ordered extent will only
1525                  * be freed by btrfs_finish_ordered_io().
1526                  */
1527                 if (ret)
1528                         goto error;
1529                 if (cur_offset > end)
1530                         break;
1531         }
1532         btrfs_release_path(path);
1533 
1534         if (cur_offset <= end && cow_start == (u64)-1) {
1535                 cow_start = cur_offset;
1536                 cur_offset = end;
1537         }
1538 
1539         if (cow_start != (u64)-1) {
1540                 ret = cow_file_range(inode, locked_page, cow_start, end, end,
1541                                      page_started, nr_written, 1, NULL);
1542                 if (ret)
1543                         goto error;
1544         }
1545 
1546 error:
1547         if (ret && cur_offset < end)
1548                 extent_clear_unlock_delalloc(inode, cur_offset, end, end,
1549                                              locked_page, EXTENT_LOCKED |
1550                                              EXTENT_DELALLOC | EXTENT_DEFRAG |
1551                                              EXTENT_DO_ACCOUNTING, PAGE_UNLOCK |
1552                                              PAGE_CLEAR_DIRTY |
1553                                              PAGE_SET_WRITEBACK |
1554                                              PAGE_END_WRITEBACK);
1555         btrfs_free_path(path);
1556         return ret;
1557 }
1558 
1559 static inline int need_force_cow(struct inode *inode, u64 start, u64 end)
1560 {
1561 
1562         if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) &&
1563             !(BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC))
1564                 return 0;
1565 
1566         /*
1567          * @defrag_bytes is a hint value, no spinlock held here,
1568          * if is not zero, it means the file is defragging.
1569          * Force cow if given extent needs to be defragged.
1570          */
1571         if (BTRFS_I(inode)->defrag_bytes &&
1572             test_range_bit(&BTRFS_I(inode)->io_tree, start, end,
1573                            EXTENT_DEFRAG, 0, NULL))
1574                 return 1;
1575 
1576         return 0;
1577 }
1578 
1579 /*
1580  * extent_io.c call back to do delayed allocation processing
1581  */
1582 static int run_delalloc_range(void *private_data, struct page *locked_page,
1583                               u64 start, u64 end, int *page_started,
1584                               unsigned long *nr_written)
1585 {
1586         struct inode *inode = private_data;
1587         int ret;
1588         int force_cow = need_force_cow(inode, start, end);
1589 
1590         if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW && !force_cow) {
1591                 ret = run_delalloc_nocow(inode, locked_page, start, end,
1592                                          page_started, 1, nr_written);
1593         } else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC && !force_cow) {
1594                 ret = run_delalloc_nocow(inode, locked_page, start, end,
1595                                          page_started, 0, nr_written);
1596         } else if (!inode_need_compress(inode, start, end)) {
1597                 ret = cow_file_range(inode, locked_page, start, end, end,
1598                                       page_started, nr_written, 1, NULL);
1599         } else {
1600                 set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
1601                         &BTRFS_I(inode)->runtime_flags);
1602                 ret = cow_file_range_async(inode, locked_page, start, end,
1603                                            page_started, nr_written);
1604         }
1605         if (ret)
1606                 btrfs_cleanup_ordered_extents(inode, start, end - start + 1);
1607         return ret;
1608 }
1609 
1610 static void btrfs_split_extent_hook(void *private_data,
1611                                     struct extent_state *orig, u64 split)
1612 {
1613         struct inode *inode = private_data;
1614         u64 size;
1615 
1616         /* not delalloc, ignore it */
1617         if (!(orig->state & EXTENT_DELALLOC))
1618                 return;
1619 
1620         size = orig->end - orig->start + 1;
1621         if (size > BTRFS_MAX_EXTENT_SIZE) {
1622                 u32 num_extents;
1623                 u64 new_size;
1624 
1625                 /*
1626                  * See the explanation in btrfs_merge_extent_hook, the same
1627                  * applies here, just in reverse.
1628                  */
1629                 new_size = orig->end - split + 1;
1630                 num_extents = count_max_extents(new_size);
1631                 new_size = split - orig->start;
1632                 num_extents += count_max_extents(new_size);
1633                 if (count_max_extents(size) >= num_extents)
1634                         return;
1635         }
1636 
1637         spin_lock(&BTRFS_I(inode)->lock);
1638         BTRFS_I(inode)->outstanding_extents++;
1639         spin_unlock(&BTRFS_I(inode)->lock);
1640 }
1641 
1642 /*
1643  * extent_io.c merge_extent_hook, used to track merged delayed allocation
1644  * extents so we can keep track of new extents that are just merged onto old
1645  * extents, such as when we are doing sequential writes, so we can properly
1646  * account for the metadata space we'll need.
1647  */
1648 static void btrfs_merge_extent_hook(void *private_data,
1649                                     struct extent_state *new,
1650                                     struct extent_state *other)
1651 {
1652         struct inode *inode = private_data;
1653         u64 new_size, old_size;
1654         u32 num_extents;
1655 
1656         /* not delalloc, ignore it */
1657         if (!(other->state & EXTENT_DELALLOC))
1658                 return;
1659 
1660         if (new->start > other->start)
1661                 new_size = new->end - other->start + 1;
1662         else
1663                 new_size = other->end - new->start + 1;
1664 
1665         /* we're not bigger than the max, unreserve the space and go */
1666         if (new_size <= BTRFS_MAX_EXTENT_SIZE) {
1667                 spin_lock(&BTRFS_I(inode)->lock);
1668                 BTRFS_I(inode)->outstanding_extents--;
1669                 spin_unlock(&BTRFS_I(inode)->lock);
1670                 return;
1671         }
1672 
1673         /*
1674          * We have to add up either side to figure out how many extents were
1675          * accounted for before we merged into one big extent.  If the number of
1676          * extents we accounted for is <= the amount we need for the new range
1677          * then we can return, otherwise drop.  Think of it like this
1678          *
1679          * [ 4k][MAX_SIZE]
1680          *
1681          * So we've grown the extent by a MAX_SIZE extent, this would mean we
1682          * need 2 outstanding extents, on one side we have 1 and the other side
1683          * we have 1 so they are == and we can return.  But in this case
1684          *
1685          * [MAX_SIZE+4k][MAX_SIZE+4k]
1686          *
1687          * Each range on their own accounts for 2 extents, but merged together
1688          * they are only 3 extents worth of accounting, so we need to drop in
1689          * this case.
1690          */
1691         old_size = other->end - other->start + 1;
1692         num_extents = count_max_extents(old_size);
1693         old_size = new->end - new->start + 1;
1694         num_extents += count_max_extents(old_size);
1695         if (count_max_extents(new_size) >= num_extents)
1696                 return;
1697 
1698         spin_lock(&BTRFS_I(inode)->lock);
1699         BTRFS_I(inode)->outstanding_extents--;
1700         spin_unlock(&BTRFS_I(inode)->lock);
1701 }
1702 
1703 static void btrfs_add_delalloc_inodes(struct btrfs_root *root,
1704                                       struct inode *inode)
1705 {
1706         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1707 
1708         spin_lock(&root->delalloc_lock);
1709         if (list_empty(&BTRFS_I(inode)->delalloc_inodes)) {
1710                 list_add_tail(&BTRFS_I(inode)->delalloc_inodes,
1711                               &root->delalloc_inodes);
1712                 set_bit(BTRFS_INODE_IN_DELALLOC_LIST,
1713                         &BTRFS_I(inode)->runtime_flags);
1714                 root->nr_delalloc_inodes++;
1715                 if (root->nr_delalloc_inodes == 1) {
1716                         spin_lock(&fs_info->delalloc_root_lock);
1717                         BUG_ON(!list_empty(&root->delalloc_root));
1718                         list_add_tail(&root->delalloc_root,
1719                                       &fs_info->delalloc_roots);
1720                         spin_unlock(&fs_info->delalloc_root_lock);
1721                 }
1722         }
1723         spin_unlock(&root->delalloc_lock);
1724 }
1725 
1726 static void btrfs_del_delalloc_inode(struct btrfs_root *root,
1727                                      struct btrfs_inode *inode)
1728 {
1729         struct btrfs_fs_info *fs_info = btrfs_sb(inode->vfs_inode.i_sb);
1730 
1731         spin_lock(&root->delalloc_lock);
1732         if (!list_empty(&inode->delalloc_inodes)) {
1733                 list_del_init(&inode->delalloc_inodes);
1734                 clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
1735                           &inode->runtime_flags);
1736                 root->nr_delalloc_inodes--;
1737                 if (!root->nr_delalloc_inodes) {
1738                         spin_lock(&fs_info->delalloc_root_lock);
1739                         BUG_ON(list_empty(&root->delalloc_root));
1740                         list_del_init(&root->delalloc_root);
1741                         spin_unlock(&fs_info->delalloc_root_lock);
1742                 }
1743         }
1744         spin_unlock(&root->delalloc_lock);
1745 }
1746 
1747 /*
1748  * extent_io.c set_bit_hook, used to track delayed allocation
1749  * bytes in this file, and to maintain the list of inodes that
1750  * have pending delalloc work to be done.
1751  */
1752 static void btrfs_set_bit_hook(void *private_data,
1753                                struct extent_state *state, unsigned *bits)
1754 {
1755         struct inode *inode = private_data;
1756 
1757         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1758 
1759         if ((*bits & EXTENT_DEFRAG) && !(*bits & EXTENT_DELALLOC))
1760                 WARN_ON(1);
1761         /*
1762          * set_bit and clear bit hooks normally require _irqsave/restore
1763          * but in this case, we are only testing for the DELALLOC
1764          * bit, which is only set or cleared with irqs on
1765          */
1766         if (!(state->state & EXTENT_DELALLOC) && (*bits & EXTENT_DELALLOC)) {
1767                 struct btrfs_root *root = BTRFS_I(inode)->root;
1768                 u64 len = state->end + 1 - state->start;
1769                 bool do_list = !btrfs_is_free_space_inode(BTRFS_I(inode));
1770 
1771                 if (*bits & EXTENT_FIRST_DELALLOC) {
1772                         *bits &= ~EXTENT_FIRST_DELALLOC;
1773                 } else {
1774                         spin_lock(&BTRFS_I(inode)->lock);
1775                         BTRFS_I(inode)->outstanding_extents++;
1776                         spin_unlock(&BTRFS_I(inode)->lock);
1777                 }
1778 
1779                 /* For sanity tests */
1780                 if (btrfs_is_testing(fs_info))
1781                         return;
1782 
1783                 percpu_counter_add_batch(&fs_info->delalloc_bytes, len,
1784                                          fs_info->delalloc_batch);
1785                 spin_lock(&BTRFS_I(inode)->lock);
1786                 BTRFS_I(inode)->delalloc_bytes += len;
1787                 if (*bits & EXTENT_DEFRAG)
1788                         BTRFS_I(inode)->defrag_bytes += len;
1789                 if (do_list && !test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
1790                                          &BTRFS_I(inode)->runtime_flags))
1791                         btrfs_add_delalloc_inodes(root, inode);
1792                 spin_unlock(&BTRFS_I(inode)->lock);
1793         }
1794 
1795         if (!(state->state & EXTENT_DELALLOC_NEW) &&
1796             (*bits & EXTENT_DELALLOC_NEW)) {
1797                 spin_lock(&BTRFS_I(inode)->lock);
1798                 BTRFS_I(inode)->new_delalloc_bytes += state->end + 1 -
1799                         state->start;
1800                 spin_unlock(&BTRFS_I(inode)->lock);
1801         }
1802 }
1803 
1804 /*
1805  * extent_io.c clear_bit_hook, see set_bit_hook for why
1806  */
1807 static void btrfs_clear_bit_hook(void *private_data,
1808                                  struct extent_state *state,
1809                                  unsigned *bits)
1810 {
1811         struct btrfs_inode *inode = BTRFS_I((struct inode *)private_data);
1812         struct btrfs_fs_info *fs_info = btrfs_sb(inode->vfs_inode.i_sb);
1813         u64 len = state->end + 1 - state->start;
1814         u32 num_extents = count_max_extents(len);
1815 
1816         if ((state->state & EXTENT_DEFRAG) && (*bits & EXTENT_DEFRAG)) {
1817                 spin_lock(&inode->lock);
1818                 inode->defrag_bytes -= len;
1819                 spin_unlock(&inode->lock);
1820         }
1821 
1822         /*
1823          * set_bit and clear bit hooks normally require _irqsave/restore
1824          * but in this case, we are only testing for the DELALLOC
1825          * bit, which is only set or cleared with irqs on
1826          */
1827         if ((state->state & EXTENT_DELALLOC) && (*bits & EXTENT_DELALLOC)) {
1828                 struct btrfs_root *root = inode->root;
1829                 bool do_list = !btrfs_is_free_space_inode(inode);
1830 
1831                 if (*bits & EXTENT_FIRST_DELALLOC) {
1832                         *bits &= ~EXTENT_FIRST_DELALLOC;
1833                 } else if (!(*bits & EXTENT_CLEAR_META_RESV)) {
1834                         spin_lock(&inode->lock);
1835                         inode->outstanding_extents -= num_extents;
1836                         spin_unlock(&inode->lock);
1837                 }
1838 
1839                 /*
1840                  * We don't reserve metadata space for space cache inodes so we
1841                  * don't need to call dellalloc_release_metadata if there is an
1842                  * error.
1843                  */
1844                 if (*bits & EXTENT_CLEAR_META_RESV &&
1845                     root != fs_info->tree_root)
1846                         btrfs_delalloc_release_metadata(inode, len);
1847 
1848                 /* For sanity tests. */
1849                 if (btrfs_is_testing(fs_info))
1850                         return;
1851 
1852                 if (root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID &&
1853                     do_list && !(state->state & EXTENT_NORESERVE) &&
1854                     (*bits & EXTENT_CLEAR_DATA_RESV))
1855                         btrfs_free_reserved_data_space_noquota(
1856                                         &inode->vfs_inode,
1857                                         state->start, len);
1858 
1859                 percpu_counter_add_batch(&fs_info->delalloc_bytes, -len,
1860                                          fs_info->delalloc_batch);
1861                 spin_lock(&inode->lock);
1862                 inode->delalloc_bytes -= len;
1863                 if (do_list && inode->delalloc_bytes == 0 &&
1864                     test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
1865                                         &inode->runtime_flags))
1866                         btrfs_del_delalloc_inode(root, inode);
1867                 spin_unlock(&inode->lock);
1868         }
1869 
1870         if ((state->state & EXTENT_DELALLOC_NEW) &&
1871             (*bits & EXTENT_DELALLOC_NEW)) {
1872                 spin_lock(&inode->lock);
1873                 ASSERT(inode->new_delalloc_bytes >= len);
1874                 inode->new_delalloc_bytes -= len;
1875                 spin_unlock(&inode->lock);
1876         }
1877 }
1878 
1879 /*
1880  * extent_io.c merge_bio_hook, this must check the chunk tree to make sure
1881  * we don't create bios that span stripes or chunks
1882  *
1883  * return 1 if page cannot be merged to bio
1884  * return 0 if page can be merged to bio
1885  * return error otherwise
1886  */
1887 int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
1888                          size_t size, struct bio *bio,
1889                          unsigned long bio_flags)
1890 {
1891         struct inode *inode = page->mapping->host;
1892         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1893         u64 logical = (u64)bio->bi_iter.bi_sector << 9;
1894         u64 length = 0;
1895         u64 map_length;
1896         int ret;
1897 
1898         if (bio_flags & EXTENT_BIO_COMPRESSED)
1899                 return 0;
1900 
1901         length = bio->bi_iter.bi_size;
1902         map_length = length;
1903         ret = btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length,
1904                               NULL, 0);
1905         if (ret < 0)
1906                 return ret;
1907         if (map_length < length + size)
1908                 return 1;
1909         return 0;
1910 }
1911 
1912 /*
1913  * in order to insert checksums into the metadata in large chunks,
1914  * we wait until bio submission time.   All the pages in the bio are
1915  * checksummed and sums are attached onto the ordered extent record.
1916  *
1917  * At IO completion time the cums attached on the ordered extent record
1918  * are inserted into the btree
1919  */
1920 static blk_status_t __btrfs_submit_bio_start(void *private_data, struct bio *bio,
1921                                     int mirror_num, unsigned long bio_flags,
1922                                     u64 bio_offset)
1923 {
1924         struct inode *inode = private_data;
1925         blk_status_t ret = 0;
1926 
1927         ret = btrfs_csum_one_bio(inode, bio, 0, 0);
1928         BUG_ON(ret); /* -ENOMEM */
1929         return 0;
1930 }
1931 
1932 /*
1933  * in order to insert checksums into the metadata in large chunks,
1934  * we wait until bio submission time.   All the pages in the bio are
1935  * checksummed and sums are attached onto the ordered extent record.
1936  *
1937  * At IO completion time the cums attached on the ordered extent record
1938  * are inserted into the btree
1939  */
1940 static blk_status_t __btrfs_submit_bio_done(void *private_data, struct bio *bio,
1941                           int mirror_num, unsigned long bio_flags,
1942                           u64 bio_offset)
1943 {
1944         struct inode *inode = private_data;
1945         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1946         blk_status_t ret;
1947 
1948         ret = btrfs_map_bio(fs_info, bio, mirror_num, 1);
1949         if (ret) {
1950                 bio->bi_status = ret;
1951                 bio_endio(bio);
1952         }
1953         return ret;
1954 }
1955 
1956 /*
1957  * extent_io.c submission hook. This does the right thing for csum calculation
1958  * on write, or reading the csums from the tree before a read
1959  */
1960 static blk_status_t btrfs_submit_bio_hook(void *private_data, struct bio *bio,
1961                                  int mirror_num, unsigned long bio_flags,
1962                                  u64 bio_offset)
1963 {
1964         struct inode *inode = private_data;
1965         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1966         struct btrfs_root *root = BTRFS_I(inode)->root;
1967         enum btrfs_wq_endio_type metadata = BTRFS_WQ_ENDIO_DATA;
1968         blk_status_t ret = 0;
1969         int skip_sum;
1970         int async = !atomic_read(&BTRFS_I(inode)->sync_writers);
1971 
1972         skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
1973 
1974         if (btrfs_is_free_space_inode(BTRFS_I(inode)))
1975                 metadata = BTRFS_WQ_ENDIO_FREE_SPACE;
1976 
1977         if (bio_op(bio) != REQ_OP_WRITE) {
1978                 ret = btrfs_bio_wq_end_io(fs_info, bio, metadata);
1979                 if (ret)
1980                         goto out;
1981 
1982                 if (bio_flags & EXTENT_BIO_COMPRESSED) {
1983                         ret = btrfs_submit_compressed_read(inode, bio,
1984                                                            mirror_num,
1985                                                            bio_flags);
1986                         goto out;
1987                 } else if (!skip_sum) {
1988                         ret = btrfs_lookup_bio_sums(inode, bio, NULL);
1989                         if (ret)
1990                                 goto out;
1991                 }
1992                 goto mapit;
1993         } else if (async && !skip_sum) {
1994                 /* csum items have already been cloned */
1995                 if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
1996                         goto mapit;
1997                 /* we're doing a write, do the async checksumming */
1998                 ret = btrfs_wq_submit_bio(fs_info, bio, mirror_num, bio_flags,
1999                                           bio_offset, inode,
2000                                           __btrfs_submit_bio_start,
2001                                           __btrfs_submit_bio_done);
2002                 goto out;
2003         } else if (!skip_sum) {
2004                 ret = btrfs_csum_one_bio(inode, bio, 0, 0);
2005                 if (ret)
2006                         goto out;
2007         }
2008 
2009 mapit:
2010         ret = btrfs_map_bio(fs_info, bio, mirror_num, 0);
2011 
2012 out:
2013         if (ret) {
2014                 bio->bi_status = ret;
2015                 bio_endio(bio);
2016         }
2017         return ret;
2018 }
2019 
2020 /*
2021  * given a list of ordered sums record them in the inode.  This happens
2022  * at IO completion time based on sums calculated at bio submission time.
2023  */
2024 static noinline int add_pending_csums(struct btrfs_trans_handle *trans,
2025                              struct inode *inode, struct list_head *list)
2026 {
2027         struct btrfs_ordered_sum *sum;
2028 
2029         list_for_each_entry(sum, list, list) {
2030                 trans->adding_csums = 1;
2031                 btrfs_csum_file_blocks(trans,
2032                        BTRFS_I(inode)->root->fs_info->csum_root, sum);
2033                 trans->adding_csums = 0;
2034         }
2035         return 0;
2036 }
2037 
2038 int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end,
2039                               struct extent_state **cached_state, int dedupe)
2040 {
2041         WARN_ON((end & (PAGE_SIZE - 1)) == 0);
2042         return set_extent_delalloc(&BTRFS_I(inode)->io_tree, start, end,
2043                                    cached_state);
2044 }
2045 
2046 /* see btrfs_writepage_start_hook for details on why this is required */
2047 struct btrfs_writepage_fixup {
2048         struct page *page;
2049         struct btrfs_work work;
2050 };
2051 
2052 static void btrfs_writepage_fixup_worker(struct btrfs_work *work)
2053 {
2054         struct btrfs_writepage_fixup *fixup;
2055         struct btrfs_ordered_extent *ordered;
2056         struct extent_state *cached_state = NULL;
2057         struct extent_changeset *data_reserved = NULL;
2058         struct page *page;
2059         struct inode *inode;
2060         u64 page_start;
2061         u64 page_end;
2062         int ret;
2063 
2064         fixup = container_of(work, struct btrfs_writepage_fixup, work);
2065         page = fixup->page;
2066 again:
2067         lock_page(page);
2068         if (!page->mapping || !PageDirty(page) || !PageChecked(page)) {
2069                 ClearPageChecked(page);
2070                 goto out_page;
2071         }
2072 
2073         inode = page->mapping->host;
2074         page_start = page_offset(page);
2075         page_end = page_offset(page) + PAGE_SIZE - 1;
2076 
2077         lock_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end,
2078                          &cached_state);
2079 
2080         /* already ordered? We're done */
2081         if (PagePrivate2(page))
2082                 goto out;
2083 
2084         ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start,
2085                                         PAGE_SIZE);
2086         if (ordered) {
2087                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start,
2088                                      page_end, &cached_state, GFP_NOFS);
2089                 unlock_page(page);
2090                 btrfs_start_ordered_extent(inode, ordered, 1);
2091                 btrfs_put_ordered_extent(ordered);
2092                 goto again;
2093         }
2094 
2095         ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start,
2096                                            PAGE_SIZE);
2097         if (ret) {
2098                 mapping_set_error(page->mapping, ret);
2099                 end_extent_writepage(page, ret, page_start, page_end);
2100                 ClearPageChecked(page);
2101                 goto out;
2102          }
2103 
2104         btrfs_set_extent_delalloc(inode, page_start, page_end, &cached_state,
2105                                   0);
2106         ClearPageChecked(page);
2107         set_page_dirty(page);
2108 out:
2109         unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start, page_end,
2110                              &cached_state, GFP_NOFS);
2111 out_page:
2112         unlock_page(page);
2113         put_page(page);
2114         kfree(fixup);
2115         extent_changeset_free(data_reserved);
2116 }
2117 
2118 /*
2119  * There are a few paths in the higher layers of the kernel that directly
2120  * set the page dirty bit without asking the filesystem if it is a
2121  * good idea.  This causes problems because we want to make sure COW
2122  * properly happens and the data=ordered rules are followed.
2123  *
2124  * In our case any range that doesn't have the ORDERED bit set
2125  * hasn't been properly setup for IO.  We kick off an async process
2126  * to fix it up.  The async helper will wait for ordered extents, set
2127  * the delalloc bit and make it safe to write the page.
2128  */
2129 static int btrfs_writepage_start_hook(struct page *page, u64 start, u64 end)
2130 {
2131         struct inode *inode = page->mapping->host;
2132         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2133         struct btrfs_writepage_fixup *fixup;
2134 
2135         /* this page is properly in the ordered list */
2136         if (TestClearPagePrivate2(page))
2137                 return 0;
2138 
2139         if (PageChecked(page))
2140                 return -EAGAIN;
2141 
2142         fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
2143         if (!fixup)
2144                 return -EAGAIN;
2145 
2146         SetPageChecked(page);
2147         get_page(page);
2148         btrfs_init_work(&fixup->work, btrfs_fixup_helper,
2149                         btrfs_writepage_fixup_worker, NULL, NULL);
2150         fixup->page = page;
2151         btrfs_queue_work(fs_info->fixup_workers, &fixup->work);
2152         return -EBUSY;
2153 }
2154 
2155 static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
2156                                        struct inode *inode, u64 file_pos,
2157                                        u64 disk_bytenr, u64 disk_num_bytes,
2158                                        u64 num_bytes, u64 ram_bytes,
2159                                        u8 compression, u8 encryption,
2160                                        u16 other_encoding, int extent_type)
2161 {
2162         struct btrfs_root *root = BTRFS_I(inode)->root;
2163         struct btrfs_file_extent_item *fi;
2164         struct btrfs_path *path;
2165         struct extent_buffer *leaf;
2166         struct btrfs_key ins;
2167         u64 qg_released;
2168         int extent_inserted = 0;
2169         int ret;
2170 
2171         path = btrfs_alloc_path();
2172         if (!path)
2173                 return -ENOMEM;
2174 
2175         /*
2176          * we may be replacing one extent in the tree with another.
2177          * The new extent is pinned in the extent map, and we don't want
2178          * to drop it from the cache until it is completely in the btree.
2179          *
2180          * So, tell btrfs_drop_extents to leave this extent in the cache.
2181          * the caller is expected to unpin it and allow it to be merged
2182          * with the others.
2183          */
2184         ret = __btrfs_drop_extents(trans, root, inode, path, file_pos,
2185                                    file_pos + num_bytes, NULL, 0,
2186                                    1, sizeof(*fi), &extent_inserted);
2187         if (ret)
2188                 goto out;
2189 
2190         if (!extent_inserted) {
2191                 ins.objectid = btrfs_ino(BTRFS_I(inode));
2192                 ins.offset = file_pos;
2193                 ins.type = BTRFS_EXTENT_DATA_KEY;
2194 
2195                 path->leave_spinning = 1;
2196                 ret = btrfs_insert_empty_item(trans, root, path, &ins,
2197                                               sizeof(*fi));
2198                 if (ret)
2199                         goto out;
2200         }
2201         leaf = path->nodes[0];
2202         fi = btrfs_item_ptr(leaf, path->slots[0],
2203                             struct btrfs_file_extent_item);
2204         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
2205         btrfs_set_file_extent_type(leaf, fi, extent_type);
2206         btrfs_set_file_extent_disk_bytenr(leaf, fi, disk_bytenr);
2207         btrfs_set_file_extent_disk_num_bytes(leaf, fi, disk_num_bytes);
2208         btrfs_set_file_extent_offset(leaf, fi, 0);
2209         btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2210         btrfs_set_file_extent_ram_bytes(leaf, fi, ram_bytes);
2211         btrfs_set_file_extent_compression(leaf, fi, compression);
2212         btrfs_set_file_extent_encryption(leaf, fi, encryption);
2213         btrfs_set_file_extent_other_encoding(leaf, fi, other_encoding);
2214 
2215         btrfs_mark_buffer_dirty(leaf);
2216         btrfs_release_path(path);
2217 
2218         inode_add_bytes(inode, num_bytes);
2219 
2220         ins.objectid = disk_bytenr;
2221         ins.offset = disk_num_bytes;
2222         ins.type = BTRFS_EXTENT_ITEM_KEY;
2223 
2224         /*
2225          * Release the reserved range from inode dirty range map, as it is
2226          * already moved into delayed_ref_head
2227          */
2228         ret = btrfs_qgroup_release_data(inode, file_pos, ram_bytes);
2229         if (ret < 0)
2230                 goto out;
2231         qg_released = ret;
2232         ret = btrfs_alloc_reserved_file_extent(trans, root->root_key.objectid,
2233                         btrfs_ino(BTRFS_I(inode)), file_pos, qg_released, &ins);
2234 out:
2235         btrfs_free_path(path);
2236 
2237         return ret;
2238 }
2239 
2240 /* snapshot-aware defrag */
2241 struct sa_defrag_extent_backref {
2242         struct rb_node node;
2243         struct old_sa_defrag_extent *old;
2244         u64 root_id;
2245         u64 inum;
2246         u64 file_pos;
2247         u64 extent_offset;
2248         u64 num_bytes;
2249         u64 generation;
2250 };
2251 
2252 struct old_sa_defrag_extent {
2253         struct list_head list;
2254         struct new_sa_defrag_extent *new;
2255 
2256         u64 extent_offset;
2257         u64 bytenr;
2258         u64 offset;
2259         u64 len;
2260         int count;
2261 };
2262 
2263 struct new_sa_defrag_extent {
2264         struct rb_root root;
2265         struct list_head head;
2266         struct btrfs_path *path;
2267         struct inode *inode;
2268         u64 file_pos;
2269         u64 len;
2270         u64 bytenr;
2271         u64 disk_len;
2272         u8 compress_type;
2273 };
2274 
2275 static int backref_comp(struct sa_defrag_extent_backref *b1,
2276                         struct sa_defrag_extent_backref *b2)
2277 {
2278         if (b1->root_id < b2->root_id)
2279                 return -1;
2280         else if (b1->root_id > b2->root_id)
2281                 return 1;
2282 
2283         if (b1->inum < b2->inum)
2284                 return -1;
2285         else if (b1->inum > b2->inum)
2286                 return 1;
2287 
2288         if (b1->file_pos < b2->file_pos)
2289                 return -1;
2290         else if (b1->file_pos > b2->file_pos)
2291                 return 1;
2292 
2293         /*
2294          * [------------------------------] ===> (a range of space)
2295          *     |<--->|   |<---->| =============> (fs/file tree A)
2296          * |<---------------------------->| ===> (fs/file tree B)
2297          *
2298          * A range of space can refer to two file extents in one tree while
2299          * refer to only one file extent in another tree.
2300          *
2301          * So we may process a disk offset more than one time(two extents in A)
2302          * and locate at the same extent(one extent in B), then insert two same
2303          * backrefs(both refer to the extent in B).
2304          */
2305         return 0;
2306 }
2307 
2308 static void backref_insert(struct rb_root *root,
2309                            struct sa_defrag_extent_backref *backref)
2310 {
2311         struct rb_node **p = &root->rb_node;
2312         struct rb_node *parent = NULL;
2313         struct sa_defrag_extent_backref *entry;
2314         int ret;
2315 
2316         while (*p) {
2317                 parent = *p;
2318                 entry = rb_entry(parent, struct sa_defrag_extent_backref, node);
2319 
2320                 ret = backref_comp(backref, entry);
2321                 if (ret < 0)
2322                         p = &(*p)->rb_left;
2323                 else
2324                         p = &(*p)->rb_right;
2325         }
2326 
2327         rb_link_node(&backref->node, parent, p);
2328         rb_insert_color(&backref->node, root);
2329 }
2330 
2331 /*
2332  * Note the backref might has changed, and in this case we just return 0.
2333  */
2334 static noinline int record_one_backref(u64 inum, u64 offset, u64 root_id,
2335                                        void *ctx)
2336 {
2337         struct btrfs_file_extent_item *extent;
2338         struct old_sa_defrag_extent *old = ctx;
2339         struct new_sa_defrag_extent *new = old->new;
2340         struct btrfs_path *path = new->path;
2341         struct btrfs_key key;
2342         struct btrfs_root *root;
2343         struct sa_defrag_extent_backref *backref;
2344         struct extent_buffer *leaf;
2345         struct inode *inode = new->inode;
2346         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2347         int slot;
2348         int ret;
2349         u64 extent_offset;
2350         u64 num_bytes;
2351 
2352         if (BTRFS_I(inode)->root->root_key.objectid == root_id &&
2353             inum == btrfs_ino(BTRFS_I(inode)))
2354                 return 0;
2355 
2356         key.objectid = root_id;
2357         key.type = BTRFS_ROOT_ITEM_KEY;
2358         key.offset = (u64)-1;
2359 
2360         root = btrfs_read_fs_root_no_name(fs_info, &key);
2361         if (IS_ERR(root)) {
2362                 if (PTR_ERR(root) == -ENOENT)
2363                         return 0;
2364                 WARN_ON(1);
2365                 btrfs_debug(fs_info, "inum=%llu, offset=%llu, root_id=%llu",
2366                          inum, offset, root_id);
2367                 return PTR_ERR(root);
2368         }
2369 
2370         key.objectid = inum;
2371         key.type = BTRFS_EXTENT_DATA_KEY;
2372         if (offset > (u64)-1 << 32)
2373                 key.offset = 0;
2374         else
2375                 key.offset = offset;
2376 
2377         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2378         if (WARN_ON(ret < 0))
2379                 return ret;
2380         ret = 0;
2381 
2382         while (1) {
2383                 cond_resched();
2384 
2385                 leaf = path->nodes[0];
2386                 slot = path->slots[0];
2387 
2388                 if (slot >= btrfs_header_nritems(leaf)) {
2389                         ret = btrfs_next_leaf(root, path);
2390                         if (ret < 0) {
2391                                 goto out;
2392                         } else if (ret > 0) {
2393                                 ret = 0;
2394                                 goto out;
2395                         }
2396                         continue;
2397                 }
2398 
2399                 path->slots[0]++;
2400 
2401                 btrfs_item_key_to_cpu(leaf, &key, slot);
2402 
2403                 if (key.objectid > inum)
2404                         goto out;
2405 
2406                 if (key.objectid < inum || key.type != BTRFS_EXTENT_DATA_KEY)
2407                         continue;
2408 
2409                 extent = btrfs_item_ptr(leaf, slot,
2410                                         struct btrfs_file_extent_item);
2411 
2412                 if (btrfs_file_extent_disk_bytenr(leaf, extent) != old->bytenr)
2413                         continue;
2414 
2415                 /*
2416                  * 'offset' refers to the exact key.offset,
2417                  * NOT the 'offset' field in btrfs_extent_data_ref, ie.
2418                  * (key.offset - extent_offset).
2419                  */
2420                 if (key.offset != offset)
2421                         continue;
2422 
2423                 extent_offset = btrfs_file_extent_offset(leaf, extent);
2424                 num_bytes = btrfs_file_extent_num_bytes(leaf, extent);
2425 
2426                 if (extent_offset >= old->extent_offset + old->offset +
2427                     old->len || extent_offset + num_bytes <=
2428                     old->extent_offset + old->offset)
2429                         continue;
2430                 break;
2431         }
2432 
2433         backref = kmalloc(sizeof(*backref), GFP_NOFS);
2434         if (!backref) {
2435                 ret = -ENOENT;
2436                 goto out;
2437         }
2438 
2439         backref->root_id = root_id;
2440         backref->inum = inum;
2441         backref->file_pos = offset;
2442         backref->num_bytes = num_bytes;
2443         backref->extent_offset = extent_offset;
2444         backref->generation = btrfs_file_extent_generation(leaf, extent);
2445         backref->old = old;
2446         backref_insert(&new->root, backref);
2447         old->count++;
2448 out:
2449         btrfs_release_path(path);
2450         WARN_ON(ret);
2451         return ret;
2452 }
2453 
2454 static noinline bool record_extent_backrefs(struct btrfs_path *path,
2455                                    struct new_sa_defrag_extent *new)
2456 {
2457         struct btrfs_fs_info *fs_info = btrfs_sb(new->inode->i_sb);
2458         struct old_sa_defrag_extent *old, *tmp;
2459         int ret;
2460 
2461         new->path = path;
2462 
2463         list_for_each_entry_safe(old, tmp, &new->head, list) {
2464                 ret = iterate_inodes_from_logical(old->bytenr +
2465                                                   old->extent_offset, fs_info,
2466                                                   path, record_one_backref,
2467                                                   old);
2468                 if (ret < 0 && ret != -ENOENT)
2469                         return false;
2470 
2471                 /* no backref to be processed for this extent */
2472                 if (!old->count) {
2473                         list_del(&old->list);
2474                         kfree(old);
2475                 }
2476         }
2477 
2478         if (list_empty(&new->head))
2479                 return false;
2480 
2481         return true;
2482 }
2483 
2484 static int relink_is_mergable(struct extent_buffer *leaf,
2485                               struct btrfs_file_extent_item *fi,
2486                               struct new_sa_defrag_extent *new)
2487 {
2488         if (btrfs_file_extent_disk_bytenr(leaf, fi) != new->bytenr)
2489                 return 0;
2490 
2491         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
2492                 return 0;
2493 
2494         if (btrfs_file_extent_compression(leaf, fi) != new->compress_type)
2495                 return 0;
2496 
2497         if (btrfs_file_extent_encryption(leaf, fi) ||
2498             btrfs_file_extent_other_encoding(leaf, fi))
2499                 return 0;
2500 
2501         return 1;
2502 }
2503 
2504 /*
2505  * Note the backref might has changed, and in this case we just return 0.
2506  */
2507 static noinline int relink_extent_backref(struct btrfs_path *path,
2508                                  struct sa_defrag_extent_backref *prev,
2509                                  struct sa_defrag_extent_backref *backref)
2510 {
2511         struct btrfs_file_extent_item *extent;
2512         struct btrfs_file_extent_item *item;
2513         struct btrfs_ordered_extent *ordered;
2514         struct btrfs_trans_handle *trans;
2515         struct btrfs_root *root;
2516         struct btrfs_key key;
2517         struct extent_buffer *leaf;
2518         struct old_sa_defrag_extent *old = backref->old;
2519         struct new_sa_defrag_extent *new = old->new;
2520         struct btrfs_fs_info *fs_info = btrfs_sb(new->inode->i_sb);
2521         struct inode *inode;
2522         struct extent_state *cached = NULL;
2523         int ret = 0;
2524         u64 start;
2525         u64 len;
2526         u64 lock_start;
2527         u64 lock_end;
2528         bool merge = false;
2529         int index;
2530 
2531         if (prev && prev->root_id == backref->root_id &&
2532             prev->inum == backref->inum &&
2533             prev->file_pos + prev->num_bytes == backref->file_pos)
2534                 merge = true;
2535 
2536         /* step 1: get root */
2537         key.objectid = backref->root_id;
2538         key.type = BTRFS_ROOT_ITEM_KEY;
2539         key.offset = (u64)-1;
2540 
2541         index = srcu_read_lock(&fs_info->subvol_srcu);
2542 
2543         root = btrfs_read_fs_root_no_name(fs_info, &key);
2544         if (IS_ERR(root)) {
2545                 srcu_read_unlock(&fs_info->subvol_srcu, index);
2546                 if (PTR_ERR(root) == -ENOENT)
2547                         return 0;
2548                 return PTR_ERR(root);
2549         }
2550 
2551         if (btrfs_root_readonly(root)) {
2552                 srcu_read_unlock(&fs_info->subvol_srcu, index);
2553                 return 0;
2554         }
2555 
2556         /* step 2: get inode */
2557         key.objectid = backref->inum;
2558         key.type = BTRFS_INODE_ITEM_KEY;
2559         key.offset = 0;
2560 
2561         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
2562         if (IS_ERR(inode)) {
2563                 srcu_read_unlock(&fs_info->subvol_srcu, index);
2564                 return 0;
2565         }
2566 
2567         srcu_read_unlock(&fs_info->subvol_srcu, index);
2568 
2569         /* step 3: relink backref */
2570         lock_start = backref->file_pos;
2571         lock_end = backref->file_pos + backref->num_bytes - 1;
2572         lock_extent_bits(&BTRFS_I(inode)->io_tree, lock_start, lock_end,
2573                          &cached);
2574 
2575         ordered = btrfs_lookup_first_ordered_extent(inode, lock_end);
2576         if (ordered) {
2577                 btrfs_put_ordered_extent(ordered);
2578                 goto out_unlock;
2579         }
2580 
2581         trans = btrfs_join_transaction(root);
2582         if (IS_ERR(trans)) {
2583                 ret = PTR_ERR(trans);
2584                 goto out_unlock;
2585         }
2586 
2587         key.objectid = backref->inum;
2588         key.type = BTRFS_EXTENT_DATA_KEY;
2589         key.offset = backref->file_pos;
2590 
2591         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2592         if (ret < 0) {
2593                 goto out_free_path;
2594         } else if (ret > 0) {
2595                 ret = 0;
2596                 goto out_free_path;
2597         }
2598 
2599         extent = btrfs_item_ptr(path->nodes[0], path->slots[0],
2600                                 struct btrfs_file_extent_item);
2601 
2602         if (btrfs_file_extent_generation(path->nodes[0], extent) !=
2603             backref->generation)
2604                 goto out_free_path;
2605 
2606         btrfs_release_path(path);
2607 
2608         start = backref->file_pos;
2609         if (backref->extent_offset < old->extent_offset + old->offset)
2610                 start += old->extent_offset + old->offset -
2611                          backref->extent_offset;
2612 
2613         len = min(backref->extent_offset + backref->num_bytes,
2614                   old->extent_offset + old->offset + old->len);
2615         len -= max(backref->extent_offset, old->extent_offset + old->offset);
2616 
2617         ret = btrfs_drop_extents(trans, root, inode, start,
2618                                  start + len, 1);
2619         if (ret)
2620                 goto out_free_path;
2621 again:
2622         key.objectid = btrfs_ino(BTRFS_I(inode));
2623         key.type = BTRFS_EXTENT_DATA_KEY;
2624         key.offset = start;
2625 
2626         path->leave_spinning = 1;
2627         if (merge) {
2628                 struct btrfs_file_extent_item *fi;
2629                 u64 extent_len;
2630                 struct btrfs_key found_key;
2631 
2632                 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
2633                 if (ret < 0)
2634                         goto out_free_path;
2635 
2636                 path->slots[0]--;
2637                 leaf = path->nodes[0];
2638                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2639 
2640                 fi = btrfs_item_ptr(leaf, path->slots[0],
2641                                     struct btrfs_file_extent_item);
2642                 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
2643 
2644                 if (extent_len + found_key.offset == start &&
2645                     relink_is_mergable(leaf, fi, new)) {
2646                         btrfs_set_file_extent_num_bytes(leaf, fi,
2647                                                         extent_len + len);
2648                         btrfs_mark_buffer_dirty(leaf);
2649                         inode_add_bytes(inode, len);
2650 
2651                         ret = 1;
2652                         goto out_free_path;
2653                 } else {
2654                         merge = false;
2655                         btrfs_release_path(path);
2656                         goto again;
2657                 }
2658         }
2659 
2660         ret = btrfs_insert_empty_item(trans, root, path, &key,
2661                                         sizeof(*extent));
2662         if (ret) {
2663                 btrfs_abort_transaction(trans, ret);
2664                 goto out_free_path;
2665         }
2666 
2667         leaf = path->nodes[0];
2668         item = btrfs_item_ptr(leaf, path->slots[0],
2669                                 struct btrfs_file_extent_item);
2670         btrfs_set_file_extent_disk_bytenr(leaf, item, new->bytenr);
2671         btrfs_set_file_extent_disk_num_bytes(leaf, item, new->disk_len);
2672         btrfs_set_file_extent_offset(leaf, item, start - new->file_pos);
2673         btrfs_set_file_extent_num_bytes(leaf, item, len);
2674         btrfs_set_file_extent_ram_bytes(leaf, item, new->len);
2675         btrfs_set_file_extent_generation(leaf, item, trans->transid);
2676         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
2677         btrfs_set_file_extent_compression(leaf, item, new->compress_type);
2678         btrfs_set_file_extent_encryption(leaf, item, 0);
2679         btrfs_set_file_extent_other_encoding(leaf, item, 0);
2680 
2681         btrfs_mark_buffer_dirty(leaf);
2682         inode_add_bytes(inode, len);
2683         btrfs_release_path(path);
2684 
2685         ret = btrfs_inc_extent_ref(trans, fs_info, new->bytenr,
2686                         new->disk_len, 0,
2687                         backref->root_id, backref->inum,
2688                         new->file_pos); /* start - extent_offset */
2689         if (ret) {
2690                 btrfs_abort_transaction(trans, ret);
2691                 goto out_free_path;
2692         }
2693 
2694         ret = 1;
2695 out_free_path:
2696         btrfs_release_path(path);
2697         path->leave_spinning = 0;
2698         btrfs_end_transaction(trans);
2699 out_unlock:
2700         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lock_start, lock_end,
2701                              &cached, GFP_NOFS);
2702         iput(inode);
2703         return ret;
2704 }
2705 
2706 static void free_sa_defrag_extent(struct new_sa_defrag_extent *new)
2707 {
2708         struct old_sa_defrag_extent *old, *tmp;
2709 
2710         if (!new)
2711                 return;
2712 
2713         list_for_each_entry_safe(old, tmp, &new->head, list) {
2714                 kfree(old);
2715         }
2716         kfree(new);
2717 }
2718 
2719 static void relink_file_extents(struct new_sa_defrag_extent *new)
2720 {
2721         struct btrfs_fs_info *fs_info = btrfs_sb(new->inode->i_sb);
2722         struct btrfs_path *path;
2723         struct sa_defrag_extent_backref *backref;
2724         struct sa_defrag_extent_backref *prev = NULL;
2725         struct inode *inode;
2726         struct btrfs_root *root;
2727         struct rb_node *node;
2728         int ret;
2729 
2730         inode = new->inode;
2731         root = BTRFS_I(inode)->root;
2732 
2733         path = btrfs_alloc_path();
2734         if (!path)
2735                 return;
2736 
2737         if (!record_extent_backrefs(path, new)) {
2738                 btrfs_free_path(path);
2739                 goto out;
2740         }
2741         btrfs_release_path(path);
2742 
2743         while (1) {
2744                 node = rb_first(&new->root);
2745                 if (!node)
2746                         break;
2747                 rb_erase(node, &new->root);
2748 
2749                 backref = rb_entry(node, struct sa_defrag_extent_backref, node);
2750 
2751                 ret = relink_extent_backref(path, prev, backref);
2752                 WARN_ON(ret < 0);
2753 
2754                 kfree(prev);
2755 
2756                 if (ret == 1)
2757                         prev = backref;
2758                 else
2759                         prev = NULL;
2760                 cond_resched();
2761         }
2762         kfree(prev);
2763 
2764         btrfs_free_path(path);
2765 out:
2766         free_sa_defrag_extent(new);
2767 
2768         atomic_dec(&fs_info->defrag_running);
2769         wake_up(&fs_info->transaction_wait);
2770 }
2771 
2772 static struct new_sa_defrag_extent *
2773 record_old_file_extents(struct inode *inode,
2774                         struct btrfs_ordered_extent *ordered)
2775 {
2776         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2777         struct btrfs_root *root = BTRFS_I(inode)->root;
2778         struct btrfs_path *path;
2779         struct btrfs_key key;
2780         struct old_sa_defrag_extent *old;
2781         struct new_sa_defrag_extent *new;
2782         int ret;
2783 
2784         new = kmalloc(sizeof(*new), GFP_NOFS);
2785         if (!new)
2786                 return NULL;
2787 
2788         new->inode = inode;
2789         new->file_pos = ordered->file_offset;
2790         new->len = ordered->len;
2791         new->bytenr = ordered->start;
2792         new->disk_len = ordered->disk_len;
2793         new->compress_type = ordered->compress_type;
2794         new->root = RB_ROOT;
2795         INIT_LIST_HEAD(&new->head);
2796 
2797         path = btrfs_alloc_path();
2798         if (!path)
2799                 goto out_kfree;
2800 
2801         key.objectid = btrfs_ino(BTRFS_I(inode));
2802         key.type = BTRFS_EXTENT_DATA_KEY;
2803         key.offset = new->file_pos;
2804 
2805         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2806         if (ret < 0)
2807                 goto out_free_path;
2808         if (ret > 0 && path->slots[0] > 0)
2809                 path->slots[0]--;
2810 
2811         /* find out all the old extents for the file range */
2812         while (1) {
2813                 struct btrfs_file_extent_item *extent;
2814                 struct extent_buffer *l;
2815                 int slot;
2816                 u64 num_bytes;
2817                 u64 offset;
2818                 u64 end;
2819                 u64 disk_bytenr;
2820                 u64 extent_offset;
2821 
2822                 l = path->nodes[0];
2823                 slot = path->slots[0];
2824 
2825                 if (slot >= btrfs_header_nritems(l)) {
2826                         ret = btrfs_next_leaf(root, path);
2827                         if (ret < 0)
2828                                 goto out_free_path;
2829                         else if (ret > 0)
2830                                 break;
2831                         continue;
2832                 }
2833 
2834                 btrfs_item_key_to_cpu(l, &key, slot);
2835 
2836                 if (key.objectid != btrfs_ino(BTRFS_I(inode)))
2837                         break;
2838                 if (key.type != BTRFS_EXTENT_DATA_KEY)
2839                         break;
2840                 if (key.offset >= new->file_pos + new->len)
2841                         break;
2842 
2843                 extent = btrfs_item_ptr(l, slot, struct btrfs_file_extent_item);
2844 
2845                 num_bytes = btrfs_file_extent_num_bytes(l, extent);
2846                 if (key.offset + num_bytes < new->file_pos)
2847                         goto next;
2848 
2849                 disk_bytenr = btrfs_file_extent_disk_bytenr(l, extent);
2850                 if (!disk_bytenr)
2851                         goto next;
2852 
2853                 extent_offset = btrfs_file_extent_offset(l, extent);
2854 
2855                 old = kmalloc(sizeof(*old), GFP_NOFS);
2856                 if (!old)
2857                         goto out_free_path;
2858 
2859                 offset = max(new->file_pos, key.offset);
2860                 end = min(new->file_pos + new->len, key.offset + num_bytes);
2861 
2862                 old->bytenr = disk_bytenr;
2863                 old->extent_offset = extent_offset;
2864                 old->offset = offset - key.offset;
2865                 old->len = end - offset;
2866                 old->new = new;
2867                 old->count = 0;
2868                 list_add_tail(&old->list, &new->head);
2869 next:
2870                 path->slots[0]++;
2871                 cond_resched();
2872         }
2873 
2874         btrfs_free_path(path);
2875         atomic_inc(&fs_info->defrag_running);
2876 
2877         return new;
2878 
2879 out_free_path:
2880         btrfs_free_path(path);
2881 out_kfree:
2882         free_sa_defrag_extent(new);
2883         return NULL;
2884 }
2885 
2886 static void btrfs_release_delalloc_bytes(struct btrfs_fs_info *fs_info,
2887                                          u64 start, u64 len)
2888 {
2889         struct btrfs_block_group_cache *cache;
2890 
2891         cache = btrfs_lookup_block_group(fs_info, start);
2892         ASSERT(cache);
2893 
2894         spin_lock(&cache->lock);
2895         cache->delalloc_bytes -= len;
2896         spin_unlock(&cache->lock);
2897 
2898         btrfs_put_block_group(cache);
2899 }
2900 
2901 /* as ordered data IO finishes, this gets called so we can finish
2902  * an ordered extent if the range of bytes in the file it covers are
2903  * fully written.
2904  */
2905 static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
2906 {
2907         struct inode *inode = ordered_extent->inode;
2908         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2909         struct btrfs_root *root = BTRFS_I(inode)->root;
2910         struct btrfs_trans_handle *trans = NULL;
2911         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
2912         struct extent_state *cached_state = NULL;
2913         struct new_sa_defrag_extent *new = NULL;
2914         int compress_type = 0;
2915         int ret = 0;
2916         u64 logical_len = ordered_extent->len;
2917         bool nolock;
2918         bool truncated = false;
2919         bool range_locked = false;
2920         bool clear_new_delalloc_bytes = false;
2921 
2922         if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
2923             !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags) &&
2924             !test_bit(BTRFS_ORDERED_DIRECT, &ordered_extent->flags))
2925                 clear_new_delalloc_bytes = true;
2926 
2927         nolock = btrfs_is_free_space_inode(BTRFS_I(inode));
2928 
2929         if (test_bit(BTRFS_ORDERED_IOERR, &ordered_extent->flags)) {
2930                 ret = -EIO;
2931                 goto out;
2932         }
2933 
2934         btrfs_free_io_failure_record(BTRFS_I(inode),
2935                         ordered_extent->file_offset,
2936                         ordered_extent->file_offset +
2937                         ordered_extent->len - 1);
2938 
2939         if (test_bit(BTRFS_ORDERED_TRUNCATED, &ordered_extent->flags)) {
2940                 truncated = true;
2941                 logical_len = ordered_extent->truncated_len;
2942                 /* Truncated the entire extent, don't bother adding */
2943                 if (!logical_len)
2944                         goto out;
2945         }
2946 
2947         if (test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags)) {
2948                 BUG_ON(!list_empty(&ordered_extent->list)); /* Logic error */
2949 
2950                 /*
2951                  * For mwrite(mmap + memset to write) case, we still reserve
2952                  * space for NOCOW range.
2953                  * As NOCOW won't cause a new delayed ref, just free the space
2954                  */
2955                 btrfs_qgroup_free_data(inode, NULL, ordered_extent->file_offset,
2956                                        ordered_extent->len);
2957                 btrfs_ordered_update_i_size(inode, 0, ordered_extent);
2958                 if (nolock)
2959                         trans = btrfs_join_transaction_nolock(root);
2960                 else
2961                         trans = btrfs_join_transaction(root);
2962                 if (IS_ERR(trans)) {
2963                         ret = PTR_ERR(trans);
2964                         trans = NULL;
2965                         goto out;
2966                 }
2967                 trans->block_rsv = &fs_info->delalloc_block_rsv;
2968                 ret = btrfs_update_inode_fallback(trans, root, inode);
2969                 if (ret) /* -ENOMEM or corruption */
2970                         btrfs_abort_transaction(trans, ret);
2971                 goto out;
2972         }
2973 
2974         range_locked = true;
2975         lock_extent_bits(io_tree, ordered_extent->file_offset,
2976                          ordered_extent->file_offset + ordered_extent->len - 1,
2977                          &cached_state);
2978 
2979         ret = test_range_bit(io_tree, ordered_extent->file_offset,
2980                         ordered_extent->file_offset + ordered_extent->len - 1,
2981                         EXTENT_DEFRAG, 0, cached_state);
2982         if (ret) {
2983                 u64 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
2984                 if (0 && last_snapshot >= BTRFS_I(inode)->generation)
2985                         /* the inode is shared */
2986                         new = record_old_file_extents(inode, ordered_extent);
2987 
2988                 clear_extent_bit(io_tree, ordered_extent->file_offset,
2989                         ordered_extent->file_offset + ordered_extent->len - 1,
2990                         EXTENT_DEFRAG, 0, 0, &cached_state, GFP_NOFS);
2991         }
2992 
2993         if (nolock)
2994                 trans = btrfs_join_transaction_nolock(root);
2995         else
2996                 trans = btrfs_join_transaction(root);
2997         if (IS_ERR(trans)) {
2998                 ret = PTR_ERR(trans);
2999                 trans = NULL;
3000                 goto out;
3001         }
3002 
3003         trans->block_rsv = &fs_info->delalloc_block_rsv;
3004 
3005         if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered_extent->flags))
3006                 compress_type = ordered_extent->compress_type;
3007         if (test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
3008                 BUG_ON(compress_type);
3009                 ret = btrfs_mark_extent_written(trans, BTRFS_I(inode),
3010                                                 ordered_extent->file_offset,
3011                                                 ordered_extent->file_offset +
3012                                                 logical_len);
3013         } else {
3014                 BUG_ON(root == fs_info->tree_root);
3015                 ret = insert_reserved_file_extent(trans, inode,
3016                                                 ordered_extent->file_offset,
3017                                                 ordered_extent->start,
3018                                                 ordered_extent->disk_len,
3019                                                 logical_len, logical_len,
3020                                                 compress_type, 0, 0,
3021                                                 BTRFS_FILE_EXTENT_REG);
3022                 if (!ret)
3023                         btrfs_release_delalloc_bytes(fs_info,
3024                                                      ordered_extent->start,
3025                                                      ordered_extent->disk_len);
3026         }
3027         unpin_extent_cache(&BTRFS_I(inode)->extent_tree,
3028                            ordered_extent->file_offset, ordered_extent->len,
3029                            trans->transid);
3030         if (ret < 0) {
3031                 btrfs_abort_transaction(trans, ret);
3032                 goto out;
3033         }
3034 
3035         add_pending_csums(trans, inode, &ordered_extent->list);
3036 
3037         btrfs_ordered_update_i_size(inode, 0, ordered_extent);
3038         ret = btrfs_update_inode_fallback(trans, root, inode);
3039         if (ret) { /* -ENOMEM or corruption */
3040                 btrfs_abort_transaction(trans, ret);
3041                 goto out;
3042         }
3043         ret = 0;
3044 out:
3045         if (range_locked || clear_new_delalloc_bytes) {
3046                 unsigned int clear_bits = 0;
3047 
3048                 if (range_locked)
3049                         clear_bits |= EXTENT_LOCKED;
3050                 if (clear_new_delalloc_bytes)
3051                         clear_bits |= EXTENT_DELALLOC_NEW;
3052                 clear_extent_bit(&BTRFS_I(inode)->io_tree,
3053                                  ordered_extent->file_offset,
3054                                  ordered_extent->file_offset +
3055                                  ordered_extent->len - 1,
3056                                  clear_bits,
3057                                  (clear_bits & EXTENT_LOCKED) ? 1 : 0,
3058                                  0, &cached_state, GFP_NOFS);
3059         }
3060 
3061         if (root != fs_info->tree_root)
3062                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3063                                 ordered_extent->len);
3064         if (trans)
3065                 btrfs_end_transaction(trans);
3066 
3067         if (ret || truncated) {
3068                 u64 start, end;
3069 
3070                 if (truncated)
3071                         start = ordered_extent->file_offset + logical_len;
3072                 else
3073                         start = ordered_extent->file_offset;
3074                 end = ordered_extent->file_offset + ordered_extent->len - 1;
3075                 clear_extent_uptodate(io_tree, start, end, NULL, GFP_NOFS);
3076 
3077                 /* Drop the cache for the part of the extent we didn't write. */
3078                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
3079 
3080                 /*
3081                  * If the ordered extent had an IOERR or something else went
3082                  * wrong we need to return the space for this ordered extent
3083                  * back to the allocator.  We only free the extent in the
3084                  * truncated case if we didn't write out the extent at all.
3085                  */
3086                 if ((ret || !logical_len) &&
3087                     !test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
3088                     !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags))
3089                         btrfs_free_reserved_extent(fs_info,
3090                                                    ordered_extent->start,
3091                                                    ordered_extent->disk_len, 1);
3092         }
3093 
3094 
3095         /*
3096          * This needs to be done to make sure anybody waiting knows we are done
3097          * updating everything for this ordered extent.
3098          */
3099         btrfs_remove_ordered_extent(inode, ordered_extent);
3100 
3101         /* for snapshot-aware defrag */
3102         if (new) {
3103                 if (ret) {
3104                         free_sa_defrag_extent(new);
3105                         atomic_dec(&fs_info->defrag_running);
3106                 } else {
3107                         relink_file_extents(new);
3108                 }
3109         }
3110 
3111         /* once for us */
3112         btrfs_put_ordered_extent(ordered_extent);
3113         /* once for the tree */
3114         btrfs_put_ordered_extent(ordered_extent);
3115 
3116         return ret;
3117 }
3118 
3119 static void finish_ordered_fn(struct btrfs_work *work)
3120 {
3121         struct btrfs_ordered_extent *ordered_extent;
3122         ordered_extent = container_of(work, struct btrfs_ordered_extent, work);
3123         btrfs_finish_ordered_io(ordered_extent);
3124 }
3125 
3126 static void btrfs_writepage_end_io_hook(struct page *page, u64 start, u64 end,
3127                                 struct extent_state *state, int uptodate)
3128 {
3129         struct inode *inode = page->mapping->host;
3130         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3131         struct btrfs_ordered_extent *ordered_extent = NULL;
3132         struct btrfs_workqueue *wq;
3133         btrfs_work_func_t func;
3134 
3135         trace_btrfs_writepage_end_io_hook(page, start, end, uptodate);
3136 
3137         ClearPagePrivate2(page);
3138         if (!btrfs_dec_test_ordered_pending(inode, &ordered_extent, start,
3139                                             end - start + 1, uptodate))
3140                 return;
3141 
3142         if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
3143                 wq = fs_info->endio_freespace_worker;
3144                 func = btrfs_freespace_write_helper;
3145         } else {
3146                 wq = fs_info->endio_write_workers;
3147                 func = btrfs_endio_write_helper;
3148         }
3149 
3150         btrfs_init_work(&ordered_extent->work, func, finish_ordered_fn, NULL,
3151                         NULL);
3152         btrfs_queue_work(wq, &ordered_extent->work);
3153 }
3154 
3155 static int __readpage_endio_check(struct inode *inode,
3156                                   struct btrfs_io_bio *io_bio,
3157                                   int icsum, struct page *page,
3158                                   int pgoff, u64 start, size_t len)
3159 {
3160         char *kaddr;
3161         u32 csum_expected;
3162         u32 csum = ~(u32)0;
3163 
3164         csum_expected = *(((u32 *)io_bio->csum) + icsum);
3165 
3166         kaddr = kmap_atomic(page);
3167         csum = btrfs_csum_data(kaddr + pgoff, csum,  len);
3168         btrfs_csum_final(csum, (u8 *)&csum);
3169         if (csum != csum_expected)
3170                 goto zeroit;
3171 
3172         kunmap_atomic(kaddr);
3173         return 0;
3174 zeroit:
3175         btrfs_print_data_csum_error(BTRFS_I(inode), start, csum, csum_expected,
3176                                     io_bio->mirror_num);
3177         memset(kaddr + pgoff, 1, len);
3178         flush_dcache_page(page);
3179         kunmap_atomic(kaddr);
3180         return -EIO;
3181 }
3182 
3183 /*
3184  * when reads are done, we need to check csums to verify the data is correct
3185  * if there's a match, we allow the bio to finish.  If not, the code in
3186  * extent_io.c will try to find good copies for us.
3187  */
3188 static int btrfs_readpage_end_io_hook(struct btrfs_io_bio *io_bio,
3189                                       u64 phy_offset, struct page *page,
3190                                       u64 start, u64 end, int mirror)
3191 {
3192         size_t offset = start - page_offset(page);
3193         struct inode *inode = page->mapping->host;
3194         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
3195         struct btrfs_root *root = BTRFS_I(inode)->root;
3196 
3197         if (PageChecked(page)) {
3198                 ClearPageChecked(page);
3199                 return 0;
3200         }
3201 
3202         if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
3203                 return 0;
3204 
3205         if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID &&
3206             test_range_bit(io_tree, start, end, EXTENT_NODATASUM, 1, NULL)) {
3207                 clear_extent_bits(io_tree, start, end, EXTENT_NODATASUM);
3208                 return 0;
3209         }
3210 
3211         phy_offset >>= inode->i_sb->s_blocksize_bits;
3212         return __readpage_endio_check(inode, io_bio, phy_offset, page, offset,
3213                                       start, (size_t)(end - start + 1));
3214 }
3215 
3216 void btrfs_add_delayed_iput(struct inode *inode)
3217 {
3218         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3219         struct btrfs_inode *binode = BTRFS_I(inode);
3220 
3221         if (atomic_add_unless(&inode->i_count, -1, 1))
3222                 return;
3223 
3224         spin_lock(&fs_info->delayed_iput_lock);
3225         if (binode->delayed_iput_count == 0) {
3226                 ASSERT(list_empty(&binode->delayed_iput));
3227                 list_add_tail(&binode->delayed_iput, &fs_info->delayed_iputs);
3228         } else {
3229                 binode->delayed_iput_count++;
3230         }
3231         spin_unlock(&fs_info->delayed_iput_lock);
3232 }
3233 
3234 void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info)
3235 {
3236 
3237         spin_lock(&fs_info->delayed_iput_lock);
3238         while (!list_empty(&fs_info->delayed_iputs)) {
3239                 struct btrfs_inode *inode;
3240 
3241                 inode = list_first_entry(&fs_info->delayed_iputs,
3242                                 struct btrfs_inode, delayed_iput);
3243                 if (inode->delayed_iput_count) {
3244                         inode->delayed_iput_count--;
3245                         list_move_tail(&inode->delayed_iput,
3246                                         &fs_info->delayed_iputs);
3247                 } else {
3248                         list_del_init(&inode->delayed_iput);
3249                 }
3250                 spin_unlock(&fs_info->delayed_iput_lock);
3251                 iput(&inode->vfs_inode);
3252                 spin_lock(&fs_info->delayed_iput_lock);
3253         }
3254         spin_unlock(&fs_info->delayed_iput_lock);
3255 }
3256 
3257 /*
3258  * This is called in transaction commit time. If there are no orphan
3259  * files in the subvolume, it removes orphan item and frees block_rsv
3260  * structure.
3261  */
3262 void btrfs_orphan_commit_root(struct btrfs_trans_handle *trans,
3263                               struct btrfs_root *root)
3264 {
3265         struct btrfs_fs_info *fs_info = root->fs_info;
3266         struct btrfs_block_rsv *block_rsv;
3267         int ret;
3268 
3269         if (atomic_read(&root->orphan_inodes) ||
3270             root->orphan_cleanup_state != ORPHAN_CLEANUP_DONE)
3271                 return;
3272 
3273         spin_lock(&root->orphan_lock);
3274         if (atomic_read(&root->orphan_inodes)) {
3275                 spin_unlock(&root->orphan_lock);
3276                 return;
3277         }
3278 
3279         if (root->orphan_cleanup_state != ORPHAN_CLEANUP_DONE) {
3280                 spin_unlock(&root->orphan_lock);
3281                 return;
3282         }
3283 
3284         block_rsv = root->orphan_block_rsv;
3285         root->orphan_block_rsv = NULL;
3286         spin_unlock(&root->orphan_lock);
3287 
3288         if (test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state) &&
3289             btrfs_root_refs(&root->root_item) > 0) {
3290                 ret = btrfs_del_orphan_item(trans, fs_info->tree_root,
3291                                             root->root_key.objectid);
3292                 if (ret)
3293                         btrfs_abort_transaction(trans, ret);
3294                 else
3295                         clear_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
3296                                   &root->state);
3297         }
3298 
3299         if (block_rsv) {
3300                 WARN_ON(block_rsv->size > 0);
3301                 btrfs_free_block_rsv(fs_info, block_rsv);
3302         }
3303 }
3304 
3305 /*
3306  * This creates an orphan entry for the given inode in case something goes
3307  * wrong in the middle of an unlink/truncate.
3308  *
3309  * NOTE: caller of this function should reserve 5 units of metadata for
3310  *       this function.
3311  */
3312 int btrfs_orphan_add(struct btrfs_trans_handle *trans,
3313                 struct btrfs_inode *inode)
3314 {
3315         struct btrfs_fs_info *fs_info = btrfs_sb(inode->vfs_inode.i_sb);
3316         struct btrfs_root *root = inode->root;
3317         struct btrfs_block_rsv *block_rsv = NULL;
3318         int reserve = 0;
3319         int insert = 0;
3320         int ret;
3321 
3322         if (!root->orphan_block_rsv) {
3323                 block_rsv = btrfs_alloc_block_rsv(fs_info,
3324                                                   BTRFS_BLOCK_RSV_TEMP);
3325                 if (!block_rsv)
3326                         return -ENOMEM;
3327         }
3328 
3329         spin_lock(&root->orphan_lock);
3330         if (!root->orphan_block_rsv) {
3331                 root->orphan_block_rsv = block_rsv;
3332         } else if (block_rsv) {
3333                 btrfs_free_block_rsv(fs_info, block_rsv);
3334                 block_rsv = NULL;
3335         }
3336 
3337         if (!test_and_set_bit(BTRFS_INODE_HAS_ORPHAN_ITEM,
3338                               &inode->runtime_flags)) {
3339 #if 0
3340                 /*
3341                  * For proper ENOSPC handling, we should do orphan
3342                  * cleanup when mounting. But this introduces backward
3343                  * compatibility issue.
3344                  */
3345                 if (!xchg(&root->orphan_item_inserted, 1))
3346                         insert = 2;
3347                 else
3348                         insert = 1;
3349 #endif
3350                 insert = 1;
3351                 atomic_inc(&root->orphan_inodes);
3352         }
3353 
3354         if (!test_and_set_bit(BTRFS_INODE_ORPHAN_META_RESERVED,
3355                               &inode->runtime_flags))
3356                 reserve = 1;
3357         spin_unlock(&root->orphan_lock);
3358 
3359         /* grab metadata reservation from transaction handle */
3360         if (reserve) {
3361                 ret = btrfs_orphan_reserve_metadata(trans, inode);
3362                 ASSERT(!ret);
3363                 if (ret) {
3364                         atomic_dec(&root->orphan_inodes);
3365                         clear_bit(BTRFS_INODE_ORPHAN_META_RESERVED,
3366                                   &inode->runtime_flags);
3367                         if (insert)
3368                                 clear_bit(BTRFS_INODE_HAS_ORPHAN_ITEM,
3369                                           &inode->runtime_flags);
3370                         return ret;
3371                 }
3372         }
3373 
3374         /* insert an orphan item to track this unlinked/truncated file */
3375         if (insert >= 1) {
3376                 ret = btrfs_insert_orphan_item(trans, root, btrfs_ino(inode));
3377                 if (ret) {
3378                         atomic_dec(&root->orphan_inodes);
3379                         if (reserve) {
3380                                 clear_bit(BTRFS_INODE_ORPHAN_META_RESERVED,
3381                                           &inode->runtime_flags);
3382                                 btrfs_orphan_release_metadata(inode);
3383                         }
3384                         if (ret != -EEXIST) {
3385                                 clear_bit(BTRFS_INODE_HAS_ORPHAN_ITEM,
3386                                           &inode->runtime_flags);
3387                                 btrfs_abort_transaction(trans, ret);
3388                                 return ret;
3389                         }
3390                 }
3391                 ret = 0;
3392         }
3393 
3394         /* insert an orphan item to track subvolume contains orphan files */
3395         if (insert >= 2) {
3396                 ret = btrfs_insert_orphan_item(trans, fs_info->tree_root,
3397                                                root->root_key.objectid);
3398                 if (ret && ret != -EEXIST) {
3399                         btrfs_abort_transaction(trans, ret);
3400                         return ret;
3401                 }
3402         }
3403         return 0;
3404 }
3405 
3406 /*
3407  * We have done the truncate/delete so we can go ahead and remove the orphan
3408  * item for this particular inode.
3409  */
3410 static int btrfs_orphan_del(struct btrfs_trans_handle *trans,
3411                             struct btrfs_inode *inode)
3412 {
3413         struct btrfs_root *root = inode->root;
3414         int delete_item = 0;
3415         int release_rsv = 0;
3416         int ret = 0;
3417 
3418         spin_lock(&root->orphan_lock);
3419         if (test_and_clear_bit(BTRFS_INODE_HAS_ORPHAN_ITEM,
3420                                &inode->runtime_flags))
3421                 delete_item = 1;
3422 
3423         if (test_and_clear_bit(BTRFS_INODE_ORPHAN_META_RESERVED,
3424                                &inode->runtime_flags))
3425                 release_rsv = 1;
3426         spin_unlock(&root->orphan_lock);
3427 
3428         if (delete_item) {
3429                 atomic_dec(&root->orphan_inodes);
3430                 if (trans)
3431                         ret = btrfs_del_orphan_item(trans, root,
3432                                                     btrfs_ino(inode));
3433         }
3434 
3435         if (release_rsv)
3436                 btrfs_orphan_release_metadata(inode);
3437 
3438         return ret;
3439 }
3440 
3441 /*
3442  * this cleans up any orphans that may be left on the list from the last use
3443  * of this root.
3444  */
3445 int btrfs_orphan_cleanup(struct btrfs_root *root)
3446 {
3447         struct btrfs_fs_info *fs_info = root->fs_info;
3448         struct btrfs_path *path;
3449         struct extent_buffer *leaf;
3450         struct btrfs_key key, found_key;
3451         struct btrfs_trans_handle *trans;
3452         struct inode *inode;
3453         u64 last_objectid = 0;
3454         int ret = 0, nr_unlink = 0, nr_truncate = 0;
3455 
3456         if (cmpxchg(&root->orphan_cleanup_state, 0, ORPHAN_CLEANUP_STARTED))
3457                 return 0;
3458 
3459         path = btrfs_alloc_path();
3460         if (!path) {
3461                 ret = -ENOMEM;
3462                 goto out;
3463         }
3464         path->reada = READA_BACK;
3465 
3466         key.objectid = BTRFS_ORPHAN_OBJECTID;
3467         key.type = BTRFS_ORPHAN_ITEM_KEY;
3468         key.offset = (u64)-1;
3469 
3470         while (1) {
3471                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3472                 if (ret < 0)
3473                         goto out;
3474 
3475                 /*
3476                  * if ret == 0 means we found what we were searching for, which
3477                  * is weird, but possible, so only screw with path if we didn't
3478                  * find the key and see if we have stuff that matches
3479                  */
3480                 if (ret > 0) {
3481                         ret = 0;
3482                         if (path->slots[0] == 0)
3483                                 break;
3484                         path->slots[0]--;
3485                 }
3486 
3487                 /* pull out the item */
3488                 leaf = path->nodes[0];
3489                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
3490 
3491                 /* make sure the item matches what we want */
3492                 if (found_key.objectid != BTRFS_ORPHAN_OBJECTID)
3493                         break;
3494                 if (found_key.type != BTRFS_ORPHAN_ITEM_KEY)
3495                         break;
3496 
3497                 /* release the path since we're done with it */
3498                 btrfs_release_path(path);
3499 
3500                 /*
3501                  * this is where we are basically btrfs_lookup, without the
3502                  * crossing root thing.  we store the inode number in the
3503                  * offset of the orphan item.
3504                  */
3505 
3506                 if (found_key.offset == last_objectid) {
3507                         btrfs_err(fs_info,
3508                                   "Error removing orphan entry, stopping orphan cleanup");
3509                         ret = -EINVAL;
3510                         goto out;
3511                 }
3512 
3513                 last_objectid = found_key.offset;
3514 
3515                 found_key.objectid = found_key.offset;
3516                 found_key.type = BTRFS_INODE_ITEM_KEY;
3517                 found_key.offset = 0;
3518                 inode = btrfs_iget(fs_info->sb, &found_key, root, NULL);
3519                 ret = PTR_ERR_OR_ZERO(inode);
3520                 if (ret && ret != -ENOENT)
3521                         goto out;
3522 
3523                 if (ret == -ENOENT && root == fs_info->tree_root) {
3524                         struct btrfs_root *dead_root;
3525                         struct btrfs_fs_info *fs_info = root->fs_info;
3526                         int is_dead_root = 0;
3527 
3528                         /*
3529                          * this is an orphan in the tree root. Currently these
3530                          * could come from 2 sources:
3531                          *  a) a snapshot deletion in progress
3532                          *  b) a free space cache inode
3533                          * We need to distinguish those two, as the snapshot
3534                          * orphan must not get deleted.
3535                          * find_dead_roots already ran before us, so if this
3536                          * is a snapshot deletion, we should find the root
3537                          * in the dead_roots list
3538                          */
3539                         spin_lock(&fs_info->trans_lock);
3540                         list_for_each_entry(dead_root, &fs_info->dead_roots,
3541                                             root_list) {
3542                                 if (dead_root->root_key.objectid ==
3543                                     found_key.objectid) {
3544                                         is_dead_root = 1;
3545                                         break;
3546                                 }
3547                         }
3548                         spin_unlock(&fs_info->trans_lock);
3549                         if (is_dead_root) {
3550                                 /* prevent this orphan from being found again */
3551                                 key.offset = found_key.objectid - 1;
3552                                 continue;
3553                         }
3554                 }
3555                 /*
3556                  * Inode is already gone but the orphan item is still there,
3557                  * kill the orphan item.
3558                  */
3559                 if (ret == -ENOENT) {
3560                         trans = btrfs_start_transaction(root, 1);
3561                         if (IS_ERR(trans)) {
3562                                 ret = PTR_ERR(trans);
3563                                 goto out;
3564                         }
3565                         btrfs_debug(fs_info, "auto deleting %Lu",
3566                                     found_key.objectid);
3567                         ret = btrfs_del_orphan_item(trans, root,
3568                                                     found_key.objectid);
3569                         btrfs_end_transaction(trans);
3570                         if (ret)
3571                                 goto out;
3572                         continue;
3573                 }
3574 
3575                 /*
3576                  * add this inode to the orphan list so btrfs_orphan_del does
3577                  * the proper thing when we hit it
3578                  */
3579                 set_bit(BTRFS_INODE_HAS_ORPHAN_ITEM,
3580                         &BTRFS_I(inode)->runtime_flags);
3581                 atomic_inc(&root->orphan_inodes);
3582 
3583                 /* if we have links, this was a truncate, lets do that */
3584                 if (inode->i_nlink) {
3585                         if (WARN_ON(!S_ISREG(inode->i_mode))) {
3586                                 iput(inode);
3587                                 continue;
3588                         }
3589                         nr_truncate++;
3590 
3591                         /* 1 for the orphan item deletion. */
3592                         trans = btrfs_start_transaction(root, 1);
3593                         if (IS_ERR(trans)) {
3594                                 iput(inode);
3595                                 ret = PTR_ERR(trans);
3596                                 goto out;
3597                         }
3598                         ret = btrfs_orphan_add(trans, BTRFS_I(inode));
3599                         btrfs_end_transaction(trans);
3600                         if (ret) {
3601                                 iput(inode);
3602                                 goto out;
3603                         }
3604 
3605                         ret = btrfs_truncate(inode);
3606                         if (ret)
3607                                 btrfs_orphan_del(NULL, BTRFS_I(inode));
3608                 } else {
3609                         nr_unlink++;
3610                 }
3611 
3612                 /* this will do delete_inode and everything for us */
3613                 iput(inode);
3614                 if (ret)
3615                         goto out;
3616         }
3617         /* release the path since we're done with it */
3618         btrfs_release_path(path);
3619 
3620         root->orphan_cleanup_state = ORPHAN_CLEANUP_DONE;
3621 
3622         if (root->orphan_block_rsv)
3623                 btrfs_block_rsv_release(fs_info, root->orphan_block_rsv,
3624                                         (u64)-1);
3625 
3626         if (root->orphan_block_rsv ||
3627             test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state)) {
3628                 trans = btrfs_join_transaction(root);
3629                 if (!IS_ERR(trans))
3630                         btrfs_end_transaction(trans);
3631         }
3632 
3633         if (nr_unlink)
3634                 btrfs_debug(fs_info, "unlinked %d orphans", nr_unlink);
3635         if (nr_truncate)
3636                 btrfs_debug(fs_info, "truncated %d orphans", nr_truncate);
3637 
3638 out:
3639         if (ret)
3640                 btrfs_err(fs_info, "could not do orphan cleanup %d", ret);
3641         btrfs_free_path(path);
3642         return ret;
3643 }
3644 
3645 /*
3646  * very simple check to peek ahead in the leaf looking for xattrs.  If we
3647  * don't find any xattrs, we know there can't be any acls.
3648  *
3649  * slot is the slot the inode is in, objectid is the objectid of the inode
3650  */
3651 static noinline int acls_after_inode_item(struct extent_buffer *leaf,
3652                                           int slot, u64 objectid,
3653                                           int *first_xattr_slot)
3654 {
3655         u32 nritems = btrfs_header_nritems(leaf);
3656         struct btrfs_key found_key;
3657         static u64 xattr_access = 0;
3658         static u64 xattr_default = 0;
3659         int scanned = 0;
3660 
3661         if (!xattr_access) {
3662                 xattr_access = btrfs_name_hash(XATTR_NAME_POSIX_ACL_ACCESS,
3663                                         strlen(XATTR_NAME_POSIX_ACL_ACCESS));
3664                 xattr_default = btrfs_name_hash(XATTR_NAME_POSIX_ACL_DEFAULT,
3665                                         strlen(XATTR_NAME_POSIX_ACL_DEFAULT));
3666         }
3667 
3668         slot++;
3669         *first_xattr_slot = -1;
3670         while (slot < nritems) {
3671                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
3672 
3673                 /* we found a different objectid, there must not be acls */
3674                 if (found_key.objectid != objectid)
3675                         return 0;
3676 
3677                 /* we found an xattr, assume we've got an acl */
3678                 if (found_key.type == BTRFS_XATTR_ITEM_KEY) {
3679                         if (*first_xattr_slot == -1)
3680                                 *first_xattr_slot = slot;
3681                         if (found_key.offset == xattr_access ||
3682                             found_key.offset == xattr_default)
3683                                 return 1;
3684                 }
3685 
3686                 /*
3687                  * we found a key greater than an xattr key, there can't
3688                  * be any acls later on
3689                  */
3690                 if (found_key.type > BTRFS_XATTR_ITEM_KEY)
3691                         return 0;
3692 
3693                 slot++;
3694                 scanned++;
3695 
3696                 /*
3697                  * it goes inode, inode backrefs, xattrs, extents,
3698                  * so if there are a ton of hard links to an inode there can
3699                  * be a lot of backrefs.  Don't waste time searching too hard,
3700                  * this is just an optimization
3701                  */
3702                 if (scanned >= 8)
3703                         break;
3704         }
3705         /* we hit the end of the leaf before we found an xattr or
3706          * something larger than an xattr.  We have to assume the inode
3707          * has acls
3708          */
3709         if (*first_xattr_slot == -1)
3710                 *first_xattr_slot = slot;
3711         return 1;
3712 }
3713 
3714 /*
3715  * read an inode from the btree into the in-memory inode
3716  */
3717 static int btrfs_read_locked_inode(struct inode *inode)
3718 {
3719         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3720         struct btrfs_path *path;
3721         struct extent_buffer *leaf;
3722         struct btrfs_inode_item *inode_item;
3723         struct btrfs_root *root = BTRFS_I(inode)->root;
3724         struct btrfs_key location;
3725         unsigned long ptr;
3726         int maybe_acls;
3727         u32 rdev;
3728         int ret;
3729         bool filled = false;
3730         int first_xattr_slot;
3731 
3732         ret = btrfs_fill_inode(inode, &rdev);
3733         if (!ret)
3734                 filled = true;
3735 
3736         path = btrfs_alloc_path();
3737         if (!path) {
3738                 ret = -ENOMEM;
3739                 goto make_bad;
3740         }
3741 
3742         memcpy(&location, &BTRFS_I(inode)->location, sizeof(location));
3743 
3744         ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
3745         if (ret) {
3746                 if (ret > 0)
3747                         ret = -ENOENT;
3748                 goto make_bad;
3749         }
3750 
3751         leaf = path->nodes[0];
3752 
3753         if (filled)
3754                 goto cache_index;
3755 
3756         inode_item = btrfs_item_ptr(leaf, path->slots[0],
3757                                     struct btrfs_inode_item);
3758         inode->i_mode = btrfs_inode_mode(leaf, inode_item);
3759         set_nlink(inode, btrfs_inode_nlink(leaf, inode_item));
3760         i_uid_write(inode, btrfs_inode_uid(leaf, inode_item));
3761         i_gid_write(inode, btrfs_inode_gid(leaf, inode_item));
3762         btrfs_i_size_write(BTRFS_I(inode), btrfs_inode_size(leaf, inode_item));
3763 
3764         inode->i_atime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->atime);
3765         inode->i_atime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->atime);
3766 
3767         inode->i_mtime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->mtime);
3768         inode->i_mtime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->mtime);
3769 
3770         inode->i_ctime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->ctime);
3771         inode->i_ctime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->ctime);
3772 
3773         BTRFS_I(inode)->i_otime.tv_sec =
3774                 btrfs_timespec_sec(leaf, &inode_item->otime);
3775         BTRFS_I(inode)->i_otime.tv_nsec =
3776                 btrfs_timespec_nsec(leaf, &inode_item->otime);
3777 
3778         inode_set_bytes(inode, btrfs_inode_nbytes(leaf, inode_item));
3779         BTRFS_I(inode)->generation = btrfs_inode_generation(leaf, inode_item);
3780         BTRFS_I(inode)->last_trans = btrfs_inode_transid(leaf, inode_item);
3781 
3782         inode->i_version = btrfs_inode_sequence(leaf, inode_item);
3783         inode->i_generation = BTRFS_I(inode)->generation;
3784         inode->i_rdev = 0;
3785         rdev = btrfs_inode_rdev(leaf, inode_item);
3786 
3787         BTRFS_I(inode)->index_cnt = (u64)-1;
3788         BTRFS_I(inode)->flags = btrfs_inode_flags(leaf, inode_item);
3789 
3790 cache_index:
3791         /*
3792          * If we were modified in the current generation and evicted from memory
3793          * and then re-read we need to do a full sync since we don't have any
3794          * idea about which extents were modified before we were evicted from
3795          * cache.
3796          *
3797          * This is required for both inode re-read from disk and delayed inode
3798          * in delayed_nodes_tree.
3799          */
3800         if (BTRFS_I(inode)->last_trans == fs_info->generation)
3801                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
3802                         &BTRFS_I(inode)->runtime_flags);
3803 
3804         /*
3805          * We don't persist the id of the transaction where an unlink operation
3806          * against the inode was last made. So here we assume the inode might
3807          * have been evicted, and therefore the exact value of last_unlink_trans
3808          * lost, and set it to last_trans to avoid metadata inconsistencies
3809          * between the inode and its parent if the inode is fsync'ed and the log
3810          * replayed. For example, in the scenario:
3811          *
3812          * touch mydir/foo
3813          * ln mydir/foo mydir/bar
3814          * sync
3815          * unlink mydir/bar
3816          * echo 2 > /proc/sys/vm/drop_caches   # evicts inode
3817          * xfs_io -c fsync mydir/foo
3818          * <power failure>
3819          * mount fs, triggers fsync log replay
3820          *
3821          * We must make sure that when we fsync our inode foo we also log its
3822          * parent inode, otherwise after log replay the parent still has the
3823          * dentry with the "bar" name but our inode foo has a link count of 1
3824          * and doesn't have an inode ref with the name "bar" anymore.
3825          *
3826          * Setting last_unlink_trans to last_trans is a pessimistic approach,
3827          * but it guarantees correctness at the expense of occasional full
3828          * transaction commits on fsync if our inode is a directory, or if our
3829          * inode is not a directory, logging its parent unnecessarily.
3830          */
3831         BTRFS_I(inode)->last_unlink_trans = BTRFS_I(inode)->last_trans;
3832 
3833         path->slots[0]++;
3834         if (inode->i_nlink != 1 ||
3835             path->slots[0] >= btrfs_header_nritems(leaf))
3836                 goto cache_acl;
3837 
3838         btrfs_item_key_to_cpu(leaf, &location, path->slots[0]);
3839         if (location.objectid != btrfs_ino(BTRFS_I(inode)))
3840                 goto cache_acl;
3841 
3842         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
3843         if (location.type == BTRFS_INODE_REF_KEY) {
3844                 struct btrfs_inode_ref *ref;
3845 
3846                 ref = (struct btrfs_inode_ref *)ptr;
3847                 BTRFS_I(inode)->dir_index = btrfs_inode_ref_index(leaf, ref);
3848         } else if (location.type == BTRFS_INODE_EXTREF_KEY) {
3849                 struct btrfs_inode_extref *extref;
3850 
3851                 extref = (struct btrfs_inode_extref *)ptr;
3852                 BTRFS_I(inode)->dir_index = btrfs_inode_extref_index(leaf,
3853                                                                      extref);
3854         }
3855 cache_acl:
3856         /*
3857          * try to precache a NULL acl entry for files that don't have
3858          * any xattrs or acls
3859          */
3860         maybe_acls = acls_after_inode_item(leaf, path->slots[0],
3861                         btrfs_ino(BTRFS_I(inode)), &first_xattr_slot);
3862         if (first_xattr_slot != -1) {
3863                 path->slots[0] = first_xattr_slot;
3864                 ret = btrfs_load_inode_props(inode, path);
3865                 if (ret)
3866                         btrfs_err(fs_info,
3867                                   "error loading props for ino %llu (root %llu): %d",
3868                                   btrfs_ino(BTRFS_I(inode)),
3869                                   root->root_key.objectid, ret);
3870         }
3871         btrfs_free_path(path);
3872 
3873         if (!maybe_acls)
3874                 cache_no_acl(inode);
3875 
3876         switch (inode->i_mode & S_IFMT) {
3877         case S_IFREG:
3878                 inode->i_mapping->a_ops = &btrfs_aops;
3879                 BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
3880                 inode->i_fop = &btrfs_file_operations;
3881                 inode->i_op = &btrfs_file_inode_operations;
3882                 break;
3883         case S_IFDIR:
3884                 inode->i_fop = &btrfs_dir_file_operations;
3885                 inode->i_op = &btrfs_dir_inode_operations;
3886                 break;
3887         case S_IFLNK:
3888                 inode->i_op = &btrfs_symlink_inode_operations;
3889                 inode_nohighmem(inode);
3890                 inode->i_mapping->a_ops = &btrfs_symlink_aops;
3891                 break;
3892         default:
3893                 inode->i_op = &btrfs_special_inode_operations;
3894                 init_special_inode(inode, inode->i_mode, rdev);
3895                 break;
3896         }
3897 
3898         btrfs_update_iflags(inode);
3899         return 0;
3900 
3901 make_bad:
3902         btrfs_free_path(path);
3903         make_bad_inode(inode);
3904         return ret;
3905 }
3906 
3907 /*
3908  * given a leaf and an inode, copy the inode fields into the leaf
3909  */
3910 static void fill_inode_item(struct btrfs_trans_handle *trans,
3911                             struct extent_buffer *leaf,
3912                             struct btrfs_inode_item *item,
3913                             struct inode *inode)
3914 {
3915         struct btrfs_map_token token;
3916 
3917         btrfs_init_map_token(&token);
3918 
3919         btrfs_set_token_inode_uid(leaf, item, i_uid_read(inode), &token);
3920         btrfs_set_token_inode_gid(leaf, item, i_gid_read(inode), &token);
3921         btrfs_set_token_inode_size(leaf, item, BTRFS_I(inode)->disk_i_size,
3922                                    &token);
3923         btrfs_set_token_inode_mode(leaf, item, inode->i_mode, &token);
3924         btrfs_set_token_inode_nlink(leaf, item, inode->i_nlink, &token);
3925 
3926         btrfs_set_token_timespec_sec(leaf, &item->atime,
3927                                      inode->i_atime.tv_sec, &token);
3928         btrfs_set_token_timespec_nsec(leaf, &item->atime,
3929                                       inode->i_atime.tv_nsec, &token);
3930 
3931         btrfs_set_token_timespec_sec(leaf, &item->mtime,
3932                                      inode->i_mtime.tv_sec, &token);
3933         btrfs_set_token_timespec_nsec(leaf, &item->mtime,
3934                                       inode->i_mtime.tv_nsec, &token);
3935 
3936         btrfs_set_token_timespec_sec(leaf, &item->ctime,
3937                                      inode->i_ctime.tv_sec, &token);
3938         btrfs_set_token_timespec_nsec(leaf, &item->ctime,
3939                                       inode->i_ctime.tv_nsec, &token);
3940 
3941         btrfs_set_token_timespec_sec(leaf, &item->otime,
3942                                      BTRFS_I(inode)->i_otime.tv_sec, &token);
3943         btrfs_set_token_timespec_nsec(leaf, &item->otime,
3944                                       BTRFS_I(inode)->i_otime.tv_nsec, &token);
3945 
3946         btrfs_set_token_inode_nbytes(leaf, item, inode_get_bytes(inode),
3947                                      &token);
3948         btrfs_set_token_inode_generation(leaf, item, BTRFS_I(inode)->generation,
3949                                          &token);
3950         btrfs_set_token_inode_sequence(leaf, item, inode->i_version, &token);
3951         btrfs_set_token_inode_transid(leaf, item, trans->transid, &token);
3952         btrfs_set_token_inode_rdev(leaf, item, inode->i_rdev, &token);
3953         btrfs_set_token_inode_flags(leaf, item, BTRFS_I(inode)->flags, &token);
3954         btrfs_set_token_inode_block_group(leaf, item, 0, &token);
3955 }
3956 
3957 /*
3958  * copy everything in the in-memory inode into the btree.
3959  */
3960 static noinline int btrfs_update_inode_item(struct btrfs_trans_handle *trans,
3961                                 struct btrfs_root *root, struct inode *inode)
3962 {
3963         struct btrfs_inode_item *inode_item;
3964         struct btrfs_path *path;
3965         struct extent_buffer *leaf;
3966         int ret;
3967 
3968         path = btrfs_alloc_path();
3969         if (!path)
3970                 return -ENOMEM;
3971 
3972         path->leave_spinning = 1;
3973         ret = btrfs_lookup_inode(trans, root, path, &BTRFS_I(inode)->location,
3974                                  1);
3975         if (ret) {
3976                 if (ret > 0)
3977                         ret = -ENOENT;
3978                 goto failed;
3979         }
3980 
3981         leaf = path->nodes[0];
3982         inode_item = btrfs_item_ptr(leaf, path->slots[0],
3983                                     struct btrfs_inode_item);
3984 
3985         fill_inode_item(trans, leaf, inode_item, inode);
3986         btrfs_mark_buffer_dirty(leaf);
3987         btrfs_set_inode_last_trans(trans, inode);
3988         ret = 0;
3989 failed:
3990         btrfs_free_path(path);
3991         return ret;
3992 }
3993 
3994 /*
3995  * copy everything in the in-memory inode into the btree.
3996  */
3997 noinline int btrfs_update_inode(struct btrfs_trans_handle *trans,
3998                                 struct btrfs_root *root, struct inode *inode)
3999 {
4000         struct btrfs_fs_info *fs_info = root->fs_info;
4001         int ret;
4002 
4003         /*
4004          * If the inode is a free space inode, we can deadlock during commit
4005          * if we put it into the delayed code.
4006          *
4007          * The data relocation inode should also be directly updated
4008          * without delay
4009          */
4010         if (!btrfs_is_free_space_inode(BTRFS_I(inode))
4011             && root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID
4012             && !test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags)) {
4013                 btrfs_update_root_times(trans, root);
4014 
4015                 ret = btrfs_delayed_update_inode(trans, root, inode);
4016                 if (!ret)
4017                         btrfs_set_inode_last_trans(trans, inode);
4018                 return ret;
4019         }
4020 
4021         return btrfs_update_inode_item(trans, root, inode);
4022 }
4023 
4024 noinline int btrfs_update_inode_fallback(struct btrfs_trans_handle *trans,
4025                                          struct btrfs_root *root,
4026                                          struct inode *inode)
4027 {
4028         int ret;
4029 
4030         ret = btrfs_update_inode(trans, root, inode);
4031         if (ret == -ENOSPC)
4032                 return btrfs_update_inode_item(trans, root, inode);
4033         return ret;
4034 }
4035 
4036 /*
4037  * unlink helper that gets used here in inode.c and in the tree logging
4038  * recovery code.  It remove a link in a directory with a given name, and
4039  * also drops the back refs in the inode to the directory
4040  */
4041 static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
4042                                 struct btrfs_root *root,
4043                                 struct btrfs_inode *dir,
4044                                 struct btrfs_inode *inode,
4045                                 const char *name, int name_len)
4046 {
4047         struct btrfs_fs_info *fs_info = root->fs_info;
4048         struct btrfs_path *path;
4049         int ret = 0;
4050         struct extent_buffer *leaf;
4051         struct btrfs_dir_item *di;
4052         struct btrfs_key key;
4053         u64 index;
4054         u64 ino = btrfs_ino(inode);
4055         u64 dir_ino = btrfs_ino(dir);
4056 
4057         path = btrfs_alloc_path();
4058         if (!path) {
4059                 ret = -ENOMEM;
4060                 goto out;
4061         }
4062 
4063         path->leave_spinning = 1;
4064         di = btrfs_lookup_dir_item(trans, root, path, dir_ino,
4065                                     name, name_len, -1);
4066         if (IS_ERR(di)) {
4067                 ret = PTR_ERR(di);
4068                 goto err;
4069         }
4070         if (!di) {
4071                 ret = -ENOENT;
4072                 goto err;
4073         }
4074         leaf = path->nodes[0];
4075         btrfs_dir_item_key_to_cpu(leaf, di, &key);
4076         ret = btrfs_delete_one_dir_name(trans, root, path, di);
4077         if (ret)
4078                 goto err;
4079         btrfs_release_path(path);
4080 
4081         /*
4082          * If we don't have dir index, we have to get it by looking up
4083          * the inode ref, since we get the inode ref, remove it directly,
4084          * it is unnecessary to do delayed deletion.
4085          *
4086          * But if we have dir index, needn't search inode ref to get it.
4087          * Since the inode ref is close to the inode item, it is better
4088          * that we delay to delete it, and just do this deletion when
4089          * we update the inode item.
4090          */
4091         if (inode->dir_index) {
4092                 ret = btrfs_delayed_delete_inode_ref(inode);
4093                 if (!ret) {
4094                         index = inode->dir_index;
4095                         goto skip_backref;
4096                 }
4097         }
4098 
4099         ret = btrfs_del_inode_ref(trans, root, name, name_len, ino,
4100                                   dir_ino, &index);
4101         if (ret) {
4102                 btrfs_info(fs_info,
4103                         "failed to delete reference to %.*s, inode %llu parent %llu",
4104                         name_len, name, ino, dir_ino);
4105                 btrfs_abort_transaction(trans, ret);
4106                 goto err;
4107         }
4108 skip_backref:
4109         ret = btrfs_delete_delayed_dir_index(trans, fs_info, dir, index);
4110         if (ret) {
4111                 btrfs_abort_transaction(trans, ret);
4112                 goto err;
4113         }
4114 
4115         ret = btrfs_del_inode_ref_in_log(trans, root, name, name_len, inode,
4116                         dir_ino);
4117         if (ret != 0 && ret != -ENOENT) {
4118                 btrfs_abort_transaction(trans, ret);
4119                 goto err;
4120         }
4121 
4122         ret = btrfs_del_dir_entries_in_log(trans, root, name, name_len, dir,
4123                         index);
4124         if (ret == -ENOENT)
4125                 ret = 0;
4126         else if (ret)
4127                 btrfs_abort_transaction(trans, ret);
4128 err:
4129         btrfs_free_path(path);
4130         if (ret)
4131                 goto out;
4132 
4133         btrfs_i_size_write(dir, dir->vfs_inode.i_size - name_len * 2);
4134         inode_inc_iversion(&inode->vfs_inode);
4135         inode_inc_iversion(&dir->vfs_inode);
4136         inode->vfs_inode.i_ctime = dir->vfs_inode.i_mtime =
4137                 dir->vfs_inode.i_ctime = current_time(&inode->vfs_inode);
4138         ret = btrfs_update_inode(trans, root, &dir->vfs_inode);
4139 out:
4140         return ret;
4141 }
4142 
4143 int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
4144                        struct btrfs_root *root,
4145                        struct btrfs_inode *dir, struct btrfs_inode *inode,
4146                        const char *name, int name_len)
4147 {
4148         int ret;
4149         ret = __btrfs_unlink_inode(trans, root, dir, inode, name, name_len);
4150         if (!ret) {
4151                 drop_nlink(&inode->vfs_inode);
4152                 ret = btrfs_update_inode(trans, root, &inode->vfs_inode);
4153         }
4154         return ret;
4155 }
4156 
4157 /*
4158  * helper to start transaction for unlink and rmdir.
4159  *
4160  * unlink and rmdir are special in btrfs, they do not always free space, so
4161  * if we cannot make our reservations the normal way try and see if there is
4162  * plenty of slack room in the global reserve to migrate, otherwise we cannot
4163  * allow the unlink to occur.
4164  */
4165 static struct btrfs_trans_handle *__unlink_start_trans(struct inode *dir)
4166 {
4167         struct btrfs_root *root = BTRFS_I(dir)->root;
4168 
4169         /*
4170          * 1 for the possible orphan item
4171          * 1 for the dir item
4172          * 1 for the dir index
4173          * 1 for the inode ref
4174          * 1 for the inode
4175          */
4176         return btrfs_start_transaction_fallback_global_rsv(root, 5, 5);
4177 }
4178 
4179 static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
4180 {
4181         struct btrfs_root *root = BTRFS_I(dir)->root;
4182         struct btrfs_trans_handle *trans;
4183         struct inode *inode = d_inode(dentry);
4184         int ret;
4185 
4186         trans = __unlink_start_trans(dir);
4187         if (IS_ERR(trans))
4188                 return PTR_ERR(trans);
4189 
4190         btrfs_record_unlink_dir(trans, BTRFS_I(dir), BTRFS_I(d_inode(dentry)),
4191                         0);
4192 
4193         ret = btrfs_unlink_inode(trans, root, BTRFS_I(dir),
4194                         BTRFS_I(d_inode(dentry)), dentry->d_name.name,
4195                         dentry->d_name.len);
4196         if (ret)
4197                 goto out;
4198 
4199         if (inode->i_nlink == 0) {
4200                 ret = btrfs_orphan_add(trans, BTRFS_I(inode));
4201                 if (ret)
4202                         goto out;
4203         }
4204 
4205 out:
4206         btrfs_end_transaction(trans);
4207         btrfs_btree_balance_dirty(root->fs_info);
4208         return ret;
4209 }
4210 
4211 int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
4212                         struct btrfs_root *root,
4213                         struct inode *dir, u64 objectid,
4214                         const char *name, int name_len)
4215 {
4216         struct btrfs_fs_info *fs_info = root->fs_info;
4217         struct btrfs_path *path;
4218         struct extent_buffer *leaf;
4219         struct btrfs_dir_item *di;
4220         struct btrfs_key key;
4221         u64 index;
4222         int ret;
4223         u64 dir_ino = btrfs_ino(BTRFS_I(dir));
4224 
4225         path = btrfs_alloc_path();
4226         if (!path)
4227                 return -ENOMEM;
4228 
4229         di = btrfs_lookup_dir_item(trans, root, path, dir_ino,
4230                                    name, name_len, -1);
4231         if (IS_ERR_OR_NULL(di)) {
4232                 if (!di)
4233                         ret = -ENOENT;
4234                 else
4235                         ret = PTR_ERR(di);
4236                 goto out;
4237         }
4238 
4239         leaf = path->nodes[0];
4240         btrfs_dir_item_key_to_cpu(leaf, di, &key);
4241         WARN_ON(key.type != BTRFS_ROOT_ITEM_KEY || key.objectid != objectid);
4242         ret = btrfs_delete_one_dir_name(trans, root, path, di);
4243         if (ret) {
4244                 btrfs_abort_transaction(trans, ret);
4245                 goto out;
4246         }
4247         btrfs_release_path(path);
4248 
4249         ret = btrfs_del_root_ref(trans, fs_info, objectid,
4250                                  root->root_key.objectid, dir_ino,
4251                                  &index, name, name_len);
4252         if (ret < 0) {
4253                 if (ret != -ENOENT) {
4254                         btrfs_abort_transaction(trans, ret);
4255                         goto out;
4256                 }
4257                 di = btrfs_search_dir_index_item(root, path, dir_ino,
4258                                                  name, name_len);
4259                 if (IS_ERR_OR_NULL(di)) {
4260                         if (!di)
4261                                 ret = -ENOENT;
4262                         else
4263                                 ret = PTR_ERR(di);
4264                         btrfs_abort_transaction(trans, ret);
4265                         goto out;
4266                 }
4267 
4268                 leaf = path->nodes[0];
4269                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4270                 btrfs_release_path(path);
4271                 index = key.offset;
4272         }
4273         btrfs_release_path(path);
4274 
4275         ret = btrfs_delete_delayed_dir_index(trans, fs_info, BTRFS_I(dir), index);
4276         if (ret) {
4277                 btrfs_abort_transaction(trans, ret);
4278                 goto out;
4279         }
4280 
4281         btrfs_i_size_write(BTRFS_I(dir), dir->i_size - name_len * 2);
4282         inode_inc_iversion(dir);
4283         dir->i_mtime = dir->i_ctime = current_time(dir);
4284         ret = btrfs_update_inode_fallback(trans, root, dir);
4285         if (ret)
4286                 btrfs_abort_transaction(trans, ret);
4287 out:
4288         btrfs_free_path(path);
4289         return ret;
4290 }
4291 
4292 static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
4293 {
4294         struct inode *inode = d_inode(dentry);
4295         int err = 0;
4296         struct btrfs_root *root = BTRFS_I(dir)->root;
4297         struct btrfs_trans_handle *trans;
4298         u64 last_unlink_trans;
4299 
4300         if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
4301                 return -ENOTEMPTY;
4302         if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID)
4303                 return -EPERM;
4304 
4305         trans = __unlink_start_trans(dir);
4306         if (IS_ERR(trans))
4307                 return PTR_ERR(trans);
4308 
4309         if (unlikely(btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
4310                 err = btrfs_unlink_subvol(trans, root, dir,
4311                                           BTRFS_I(inode)->location.objectid,
4312                                           dentry->d_name.name,
4313                                           dentry->d_name.len);
4314                 goto out;
4315         }
4316 
4317         err = btrfs_orphan_add(trans, BTRFS_I(inode));
4318         if (err)
4319                 goto out;
4320 
4321         last_unlink_trans = BTRFS_I(inode)->last_unlink_trans;
4322 
4323         /* now the directory is empty */
4324         err = btrfs_unlink_inode(trans, root, BTRFS_I(dir),
4325                         BTRFS_I(d_inode(dentry)), dentry->d_name.name,
4326                         dentry->d_name.len);
4327         if (!err) {
4328                 btrfs_i_size_write(BTRFS_I(inode), 0);
4329                 /*
4330                  * Propagate the last_unlink_trans value of the deleted dir to
4331                  * its parent directory. This is to prevent an unrecoverable
4332                  * log tree in the case we do something like this:
4333                  * 1) create dir foo
4334                  * 2) create snapshot under dir foo
4335                  * 3) delete the snapshot
4336                  * 4) rmdir foo
4337                  * 5) mkdir foo
4338                  * 6) fsync foo or some file inside foo
4339                  */
4340                 if (last_unlink_trans >= trans->transid)
4341                         BTRFS_I(dir)->last_unlink_trans = last_unlink_trans;
4342         }
4343 out:
4344         btrfs_end_transaction(trans);
4345         btrfs_btree_balance_dirty(root->fs_info);
4346 
4347         return err;
4348 }
4349 
4350 static int truncate_space_check(struct btrfs_trans_handle *trans,
4351                                 struct btrfs_root *root,
4352                                 u64 bytes_deleted)
4353 {
4354         struct btrfs_fs_info *fs_info = root->fs_info;
4355         int ret;
4356 
4357         /*
4358          * This is only used to apply pressure to the enospc system, we don't
4359          * intend to use this reservation at all.
4360          */
4361         bytes_deleted = btrfs_csum_bytes_to_leaves(fs_info, bytes_deleted);
4362         bytes_deleted *= fs_info->nodesize;
4363         ret = btrfs_block_rsv_add(root, &fs_info->trans_block_rsv,
4364                                   bytes_deleted, BTRFS_RESERVE_NO_FLUSH);
4365         if (!ret) {
4366                 trace_btrfs_space_reservation(fs_info, "transaction",
4367                                               trans->transid,
4368                                               bytes_deleted, 1);
4369                 trans->bytes_reserved += bytes_deleted;
4370         }
4371         return ret;
4372 
4373 }
4374 
4375 static int truncate_inline_extent(struct inode *inode,
4376                                   struct btrfs_path *path,
4377                                   struct btrfs_key *found_key,
4378                                   const u64 item_end,
4379                                   const u64 new_size)
4380 {
4381         struct extent_buffer *leaf = path->nodes[0];
4382         int slot = path->slots[0];
4383         struct btrfs_file_extent_item *fi;
4384         u32 size = (u32)(new_size - found_key->offset);
4385         struct btrfs_root *root = BTRFS_I(inode)->root;
4386 
4387         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
4388 
4389         if (btrfs_file_extent_compression(leaf, fi) != BTRFS_COMPRESS_NONE) {
4390                 loff_t offset = new_size;
4391                 loff_t page_end = ALIGN(offset, PAGE_SIZE);
4392 
4393                 /*
4394                  * Zero out the remaining of the last page of our inline extent,
4395                  * instead of directly truncating our inline extent here - that
4396                  * would be much more complex (decompressing all the data, then
4397                  * compressing the truncated data, which might be bigger than
4398                  * the size of the inline extent, resize the extent, etc).
4399                  * We release the path because to get the page we might need to
4400                  * read the extent item from disk (data not in the page cache).
4401                  */
4402                 btrfs_release_path(path);
4403                 return btrfs_truncate_block(inode, offset, page_end - offset,
4404                                         0);
4405         }
4406 
4407         btrfs_set_file_extent_ram_bytes(leaf, fi, size);
4408         size = btrfs_file_extent_calc_inline_size(size);
4409         btrfs_truncate_item(root->fs_info, path, size, 1);
4410 
4411         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state))
4412                 inode_sub_bytes(inode, item_end + 1 - new_size);
4413 
4414         return 0;
4415 }
4416 
4417 /*
4418  * this can truncate away extent items, csum items and directory items.
4419  * It starts at a high offset and removes keys until it can't find
4420  * any higher than new_size
4421  *
4422  * csum items that cross the new i_size are truncated to the new size
4423  * as well.
4424  *
4425  * min_type is the minimum key type to truncate down to.  If set to 0, this
4426  * will kill all the items on this inode, including the INODE_ITEM_KEY.
4427  */
4428 int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
4429                                struct btrfs_root *root,
4430                                struct inode *inode,
4431                                u64 new_size, u32 min_type)
4432 {
4433         struct btrfs_fs_info *fs_info = root->fs_info;
4434         struct btrfs_path *path;
4435         struct extent_buffer *leaf;
4436         struct btrfs_file_extent_item *fi;
4437         struct btrfs_key key;
4438         struct btrfs_key found_key;
4439         u64 extent_start = 0;
4440         u64 extent_num_bytes = 0;
4441         u64 extent_offset = 0;
4442         u64 item_end = 0;
4443         u64 last_size = new_size;
4444         u32 found_type = (u8)-1;
4445         int found_extent;
4446         int del_item;
4447         int pending_del_nr = 0;
4448         int pending_del_slot = 0;
4449         int extent_type = -1;
4450         int ret;
4451         int err = 0;
4452         u64 ino = btrfs_ino(BTRFS_I(inode));
4453         u64 bytes_deleted = 0;
4454         bool be_nice = 0;
4455         bool should_throttle = 0;
4456         bool should_end = 0;
4457 
4458         BUG_ON(new_size > 0 && min_type != BTRFS_EXTENT_DATA_KEY);
4459 
4460         /*
4461          * for non-free space inodes and ref cows, we want to back off from
4462          * time to time
4463          */
4464         if (!btrfs_is_free_space_inode(BTRFS_I(inode)) &&
4465             test_bit(BTRFS_ROOT_REF_COWS, &root->state))
4466                 be_nice = 1;
4467 
4468         path = btrfs_alloc_path();
4469         if (!path)
4470                 return -ENOMEM;
4471         path->reada = READA_BACK;
4472 
4473         /*
4474          * We want to drop from the next block forward in case this new size is
4475          * not block aligned since we will be keeping the last block of the
4476          * extent just the way it is.
4477          */
4478         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
4479             root == fs_info->tree_root)
4480                 btrfs_drop_extent_cache(BTRFS_I(inode), ALIGN(new_size,
4481                                         fs_info->sectorsize),
4482                                         (u64)-1, 0);
4483 
4484         /*
4485          * This function is also used to drop the items in the log tree before
4486          * we relog the inode, so if root != BTRFS_I(inode)->root, it means
4487          * it is used to drop the loged items. So we shouldn't kill the delayed
4488          * items.
4489          */
4490         if (min_type == 0 && root == BTRFS_I(inode)->root)
4491                 btrfs_kill_delayed_inode_items(BTRFS_I(inode));
4492 
4493         key.objectid = ino;
4494         key.offset = (u64)-1;
4495         key.type = (u8)-1;
4496 
4497 search_again:
4498         /*
4499          * with a 16K leaf size and 128MB extents, you can actually queue
4500          * up a huge file in a single leaf.  Most of the time that
4501          * bytes_deleted is > 0, it will be huge by the time we get here
4502          */
4503         if (be_nice && bytes_deleted > SZ_32M) {
4504                 if (btrfs_should_end_transaction(trans)) {
4505                         err = -EAGAIN;
4506                         goto error;
4507                 }
4508         }
4509 
4510 
4511         path->leave_spinning = 1;
4512         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
4513         if (ret < 0) {
4514                 err = ret;
4515                 goto out;
4516         }
4517 
4518         if (ret > 0) {
4519                 /* there are no items in the tree for us to truncate, we're
4520                  * done
4521                  */
4522                 if (path->slots[0] == 0)
4523                         goto out;
4524                 path->slots[0]--;
4525         }
4526 
4527         while (1) {
4528                 fi = NULL;
4529                 leaf = path->nodes[0];
4530                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4531                 found_type = found_key.type;
4532 
4533                 if (found_key.objectid != ino)
4534                         break;
4535 
4536                 if (found_type < min_type)
4537                         break;
4538 
4539                 item_end = found_key.offset;
4540                 if (found_type == BTRFS_EXTENT_DATA_KEY) {
4541                         fi = btrfs_item_ptr(leaf, path->slots[0],
4542                                             struct btrfs_file_extent_item);
4543                         extent_type = btrfs_file_extent_type(leaf, fi);
4544                         if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
4545                                 item_end +=
4546                                     btrfs_file_extent_num_bytes(leaf, fi);
4547 
4548                                 trace_btrfs_truncate_show_fi_regular(
4549                                         BTRFS_I(inode), leaf, fi,
4550                                         found_key.offset);
4551                         } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
4552                                 item_end += btrfs_file_extent_inline_len(leaf,
4553                                                          path->slots[0], fi);
4554 
4555                                 trace_btrfs_truncate_show_fi_inline(
4556                                         BTRFS_I(inode), leaf, fi, path->slots[0],
4557                                         found_key.offset);
4558                         }
4559                         item_end--;
4560                 }
4561                 if (found_type > min_type) {
4562                         del_item = 1;
4563                 } else {
4564                         if (item_end < new_size)
4565                                 break;
4566                         if (found_key.offset >= new_size)
4567                                 del_item = 1;
4568                         else
4569                                 del_item = 0;
4570                 }
4571                 found_extent = 0;
4572                 /* FIXME, shrink the extent if the ref count is only 1 */
4573                 if (found_type != BTRFS_EXTENT_DATA_KEY)
4574                         goto delete;
4575 
4576                 if (del_item)
4577                         last_size = found_key.offset;
4578                 else
4579                         last_size = new_size;
4580 
4581                 if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
4582                         u64 num_dec;
4583                         extent_start = btrfs_file_extent_disk_bytenr(leaf, fi);
4584                         if (!del_item) {
4585                                 u64 orig_num_bytes =
4586                                         btrfs_file_extent_num_bytes(leaf, fi);
4587                                 extent_num_bytes = ALIGN(new_size -
4588                                                 found_key.offset,
4589                                                 fs_info->sectorsize);
4590                                 btrfs_set_file_extent_num_bytes(leaf, fi,
4591                                                          extent_num_bytes);
4592                                 num_dec = (orig_num_bytes -
4593                                            extent_num_bytes);
4594                                 if (test_bit(BTRFS_ROOT_REF_COWS,
4595                                              &root->state) &&
4596                                     extent_start != 0)
4597                                         inode_sub_bytes(inode, num_dec);
4598                                 btrfs_mark_buffer_dirty(leaf);
4599                         } else {
4600                                 extent_num_bytes =
4601                                         btrfs_file_extent_disk_num_bytes(leaf,
4602                                                                          fi);
4603                                 extent_offset = found_key.offset -
4604                                         btrfs_file_extent_offset(leaf, fi);
4605 
4606                                 /* FIXME blocksize != 4096 */
4607                                 num_dec = btrfs_file_extent_num_bytes(leaf, fi);
4608                                 if (extent_start != 0) {
4609                                         found_extent = 1;
4610                                         if (test_bit(BTRFS_ROOT_REF_COWS,
4611                                                      &root->state))
4612                                                 inode_sub_bytes(inode, num_dec);
4613                                 }
4614                         }
4615                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
4616                         /*
4617                          * we can't truncate inline items that have had
4618                          * special encodings
4619                          */
4620                         if (!del_item &&
4621                             btrfs_file_extent_encryption(leaf, fi) == 0 &&
4622                             btrfs_file_extent_other_encoding(leaf, fi) == 0) {
4623 
4624                                 /*
4625                                  * Need to release path in order to truncate a
4626                                  * compressed extent. So delete any accumulated
4627                                  * extent items so far.
4628                                  */
4629                                 if (btrfs_file_extent_compression(leaf, fi) !=
4630                                     BTRFS_COMPRESS_NONE && pending_del_nr) {
4631                                         err = btrfs_del_items(trans, root, path,
4632                                                               pending_del_slot,
4633                                                               pending_del_nr);
4634                                         if (err) {
4635                                                 btrfs_abort_transaction(trans,
4636                                                                         err);
4637                                                 goto error;
4638                                         }
4639                                         pending_del_nr = 0;
4640                                 }
4641 
4642                                 err = truncate_inline_extent(inode, path,
4643                                                              &found_key,
4644                                                              item_end,
4645                                                              new_size);
4646                                 if (err) {
4647                                         btrfs_abort_transaction(trans, err);
4648                                         goto error;
4649                                 }
4650                         } else if (test_bit(BTRFS_ROOT_REF_COWS,
4651                                             &root->state)) {
4652                                 inode_sub_bytes(inode, item_end + 1 - new_size);
4653                         }
4654                 }
4655 delete:
4656                 if (del_item) {
4657                         if (!pending_del_nr) {
4658                                 /* no pending yet, add ourselves */
4659                                 pending_del_slot = path->slots[0];
4660                                 pending_del_nr = 1;
4661                         } else if (pending_del_nr &&
4662                                    path->slots[0] + 1 == pending_del_slot) {
4663                                 /* hop on the pending chunk */
4664                                 pending_del_nr++;
4665                                 pending_del_slot = path->slots[0];
4666                         } else {
4667                                 BUG();
4668                         }
4669                 } else {
4670                         break;
4671                 }
4672                 should_throttle = 0;
4673 
4674                 if (found_extent &&
4675                     (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
4676                      root == fs_info->tree_root)) {
4677                         btrfs_set_path_blocking(path);
4678                         bytes_deleted += extent_num_bytes;
4679                         ret = btrfs_free_extent(trans, fs_info, extent_start,
4680                                                 extent_num_bytes, 0,
4681                                                 btrfs_header_owner(leaf),
4682                                                 ino, extent_offset);
4683                         BUG_ON(ret);
4684                         if (btrfs_should_throttle_delayed_refs(trans, fs_info))
4685                                 btrfs_async_run_delayed_refs(fs_info,
4686                                         trans->delayed_ref_updates * 2,
4687                                         trans->transid, 0);
4688                         if (be_nice) {
4689                                 if (truncate_space_check(trans, root,
4690                                                          extent_num_bytes)) {
4691                                         should_end = 1;
4692                                 }
4693                                 if (btrfs_should_throttle_delayed_refs(trans,
4694                                                                        fs_info))
4695                                         should_throttle = 1;
4696                         }
4697                 }
4698 
4699                 if (found_type == BTRFS_INODE_ITEM_KEY)
4700                         break;
4701 
4702                 if (path->slots[0] == 0 ||
4703                     path->slots[0] != pending_del_slot ||
4704                     should_throttle || should_end) {
4705                         if (pending_del_nr) {
4706                                 ret = btrfs_del_items(trans, root, path,
4707                                                 pending_del_slot,
4708                                                 pending_del_nr);
4709                                 if (ret) {
4710                                         btrfs_abort_transaction(trans, ret);
4711                                         goto error;
4712                                 }
4713                                 pending_del_nr = 0;
4714                         }
4715                         btrfs_release_path(path);
4716                         if (should_throttle) {
4717                                 unsigned long updates = trans->delayed_ref_updates;
4718                                 if (updates) {
4719                                         trans->delayed_ref_updates = 0;
4720                                         ret = btrfs_run_delayed_refs(trans,
4721                                                                    fs_info,
4722                                                                    updates * 2);
4723                                         if (ret && !err)
4724                                                 err = ret;
4725                                 }
4726                         }
4727                         /*
4728                          * if we failed to refill our space rsv, bail out
4729                          * and let the transaction restart
4730                          */
4731                         if (should_end) {
4732                                 err = -EAGAIN;
4733                                 goto error;
4734                         }
4735                         goto search_again;
4736                 } else {
4737                         path->slots[0]--;
4738                 }
4739         }
4740 out:
4741         if (pending_del_nr) {
4742                 ret = btrfs_del_items(trans, root, path, pending_del_slot,
4743                                       pending_del_nr);
4744                 if (ret)
4745                         btrfs_abort_transaction(trans, ret);
4746         }
4747 error:
4748         if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
4749                 ASSERT(last_size >= new_size);
4750                 if (!err && last_size > new_size)
4751                         last_size = new_size;
4752                 btrfs_ordered_update_i_size(inode, last_size, NULL);
4753         }
4754 
4755         btrfs_free_path(path);
4756 
4757         if (be_nice && bytes_deleted > SZ_32M) {
4758                 unsigned long updates = trans->delayed_ref_updates;
4759                 if (updates) {
4760                         trans->delayed_ref_updates = 0;
4761                         ret = btrfs_run_delayed_refs(trans, fs_info,
4762                                                      updates * 2);
4763                         if (ret && !err)
4764                                 err = ret;
4765                 }
4766         }
4767         return err;
4768 }
4769 
4770 /*
4771  * btrfs_truncate_block - read, zero a chunk and write a block
4772  * @inode - inode that we're zeroing
4773  * @from - the offset to start zeroing
4774  * @len - the length to zero, 0 to zero the entire range respective to the
4775  *      offset
4776  * @front - zero up to the offset instead of from the offset on
4777  *
4778  * This will find the block for the "from" offset and cow the block and zero the
4779  * part we want to zero.  This is used with truncate and hole punching.
4780  */
4781 int btrfs_truncate_block(struct inode *inode, loff_t from, loff_t len,
4782                         int front)
4783 {
4784         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4785         struct address_space *mapping = inode->i_mapping;
4786         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
4787         struct btrfs_ordered_extent *ordered;
4788         struct extent_state *cached_state = NULL;
4789         struct extent_changeset *data_reserved = NULL;
4790         char *kaddr;
4791         u32 blocksize = fs_info->sectorsize;
4792         pgoff_t index = from >> PAGE_SHIFT;
4793         unsigned offset = from & (blocksize - 1);
4794         struct page *page;
4795         gfp_t mask = btrfs_alloc_write_mask(mapping);
4796         int ret = 0;
4797         u64 block_start;
4798         u64 block_end;
4799 
4800         if ((offset & (blocksize - 1)) == 0 &&
4801             (!len || ((len & (blocksize - 1)) == 0)))
4802                 goto out;
4803 
4804         ret = btrfs_delalloc_reserve_space(inode, &data_reserved,
4805                         round_down(from, blocksize), blocksize);
4806         if (ret)
4807                 goto out;
4808 
4809 again:
4810         page = find_or_create_page(mapping, index, mask);
4811         if (!page) {
4812                 btrfs_delalloc_release_space(inode, data_reserved,
4813                                 round_down(from, blocksize),
4814                                 blocksize);
4815                 ret = -ENOMEM;
4816                 goto out;
4817         }
4818 
4819         block_start = round_down(from, blocksize);
4820         block_end = block_start + blocksize - 1;
4821 
4822         if (!PageUptodate(page)) {
4823                 ret = btrfs_readpage(NULL, page);
4824                 lock_page(page);
4825                 if (page->mapping != mapping) {
4826                         unlock_page(page);
4827                         put_page(page);
4828                         goto again;
4829                 }
4830                 if (!PageUptodate(page)) {
4831                         ret = -EIO;
4832                         goto out_unlock;
4833                 }
4834         }
4835         wait_on_page_writeback(page);
4836 
4837         lock_extent_bits(io_tree, block_start, block_end, &cached_state);
4838         set_page_extent_mapped(page);
4839 
4840         ordered = btrfs_lookup_ordered_extent(inode, block_start);
4841         if (ordered) {
4842                 unlock_extent_cached(io_tree, block_start, block_end,
4843                                      &cached_state, GFP_NOFS);
4844                 unlock_page(page);
4845                 put_page(page);
4846                 btrfs_start_ordered_extent(inode, ordered, 1);
4847                 btrfs_put_ordered_extent(ordered);
4848                 goto again;
4849         }
4850 
4851         clear_extent_bit(&BTRFS_I(inode)->io_tree, block_start, block_end,
4852                           EXTENT_DIRTY | EXTENT_DELALLOC |
4853                           EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
4854                           0, 0, &cached_state, GFP_NOFS);
4855 
4856         ret = btrfs_set_extent_delalloc(inode, block_start, block_end,
4857                                         &cached_state, 0);
4858         if (ret) {
4859                 unlock_extent_cached(io_tree, block_start, block_end,
4860                                      &cached_state, GFP_NOFS);
4861                 goto out_unlock;
4862         }
4863 
4864         if (offset != blocksize) {
4865                 if (!len)
4866                         len = blocksize - offset;
4867                 kaddr = kmap(page);
4868                 if (front)
4869                         memset(kaddr + (block_start - page_offset(page)),
4870                                 0, offset);
4871                 else
4872                         memset(kaddr + (block_start - page_offset(page)) +  offset,
4873                                 0, len);
4874                 flush_dcache_page(page);
4875                 kunmap(page);
4876         }
4877         ClearPageChecked(page);
4878         set_page_dirty(page);
4879         unlock_extent_cached(io_tree, block_start, block_end, &cached_state,
4880                              GFP_NOFS);
4881 
4882 out_unlock:
4883         if (ret)
4884                 btrfs_delalloc_release_space(inode, data_reserved, block_start,
4885                                              blocksize);
4886         unlock_page(page);
4887         put_page(page);
4888 out:
4889         extent_changeset_free(data_reserved);
4890         return ret;
4891 }
4892 
4893 static int maybe_insert_hole(struct btrfs_root *root, struct inode *inode,
4894                              u64 offset, u64 len)
4895 {
4896         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4897         struct btrfs_trans_handle *trans;
4898         int ret;
4899 
4900         /*
4901          * Still need to make sure the inode looks like it's been updated so
4902          * that any holes get logged if we fsync.
4903          */
4904         if (btrfs_fs_incompat(fs_info, NO_HOLES)) {
4905                 BTRFS_I(inode)->last_trans = fs_info->generation;
4906                 BTRFS_I(inode)->last_sub_trans = root->log_transid;
4907                 BTRFS_I(inode)->last_log_commit = root->last_log_commit;
4908                 return 0;
4909         }
4910 
4911         /*
4912          * 1 - for the one we're dropping
4913          * 1 - for the one we're adding
4914          * 1 - for updating the inode.
4915          */
4916         trans = btrfs_start_transaction(root, 3);
4917         if (IS_ERR(trans))
4918                 return PTR_ERR(trans);
4919 
4920         ret = btrfs_drop_extents(trans, root, inode, offset, offset + len, 1);
4921         if (ret) {
4922                 btrfs_abort_transaction(trans, ret);
4923                 btrfs_end_transaction(trans);
4924                 return ret;
4925         }
4926 
4927         ret = btrfs_insert_file_extent(trans, root, btrfs_ino(BTRFS_I(inode)),
4928                         offset, 0, 0, len, 0, len, 0, 0, 0);
4929         if (ret)
4930                 btrfs_abort_transaction(trans, ret);
4931         else
4932                 btrfs_update_inode(trans, root, inode);
4933         btrfs_end_transaction(trans);
4934         return ret;
4935 }
4936 
4937 /*
4938  * This function puts in dummy file extents for the area we're creating a hole
4939  * for.  So if we are truncating this file to a larger size we need to insert
4940  * these file extents so that btrfs_get_extent will return a EXTENT_MAP_HOLE for
4941  * the range between oldsize and size
4942  */
4943 int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
4944 {
4945         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4946         struct btrfs_root *root = BTRFS_I(inode)->root;
4947         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
4948         struct extent_map *em = NULL;
4949         struct extent_state *cached_state = NULL;
4950         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
4951         u64 hole_start = ALIGN(oldsize, fs_info->sectorsize);
4952         u64 block_end = ALIGN(size, fs_info->sectorsize);
4953         u64 last_byte;
4954         u64 cur_offset;
4955         u64 hole_size;
4956         int err = 0;
4957 
4958         /*
4959          * If our size started in the middle of a block we need to zero out the
4960          * rest of the block before we expand the i_size, otherwise we could
4961          * expose stale data.
4962          */
4963         err = btrfs_truncate_block(inode, oldsize, 0, 0);
4964         if (err)
4965                 return err;
4966 
4967         if (size <= hole_start)
4968                 return 0;
4969 
4970         while (1) {
4971                 struct btrfs_ordered_extent *ordered;
4972 
4973                 lock_extent_bits(io_tree, hole_start, block_end - 1,
4974                                  &cached_state);
4975                 ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), hole_start,
4976                                                      block_end - hole_start);
4977                 if (!ordered)
4978                         break;
4979                 unlock_extent_cached(io_tree, hole_start, block_end - 1,
4980                                      &cached_state, GFP_NOFS);
4981                 btrfs_start_ordered_extent(inode, ordered, 1);
4982                 btrfs_put_ordered_extent(ordered);
4983         }
4984 
4985         cur_offset = hole_start;
4986         while (1) {
4987                 em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, cur_offset,
4988                                 block_end - cur_offset, 0);
4989                 if (IS_ERR(em)) {
4990                         err = PTR_ERR(em);
4991                         em = NULL;
4992                         break;
4993                 }
4994                 last_byte = min(extent_map_end(em), block_end);
4995                 last_byte = ALIGN(last_byte, fs_info->sectorsize);
4996                 if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
4997                         struct extent_map *hole_em;
4998                         hole_size = last_byte - cur_offset;
4999 
5000                         err = maybe_insert_hole(root, inode, cur_offset,
5001                                                 hole_size);
5002                         if (err)
5003                                 break;
5004                         btrfs_drop_extent_cache(BTRFS_I(inode), cur_offset,
5005                                                 cur_offset + hole_size - 1, 0);
5006                         hole_em = alloc_extent_map();
5007                         if (!hole_em) {
5008                                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
5009                                         &BTRFS_I(inode)->runtime_flags);
5010                                 goto next;
5011                         }
5012                         hole_em->start = cur_offset;
5013                         hole_em->len = hole_size;
5014                         hole_em->orig_start = cur_offset;
5015 
5016                         hole_em->block_start = EXTENT_MAP_HOLE;
5017                         hole_em->block_len = 0;
5018                         hole_em->orig_block_len = 0;
5019                         hole_em->ram_bytes = hole_size;
5020                         hole_em->bdev = fs_info->fs_devices->latest_bdev;
5021                         hole_em->compress_type = BTRFS_COMPRESS_NONE;
5022                         hole_em->generation = fs_info->generation;
5023 
5024                         while (1) {
5025                                 write_lock(&em_tree->lock);
5026                                 err = add_extent_mapping(em_tree, hole_em, 1);
5027                                 write_unlock(&em_tree->lock);
5028                                 if (err != -EEXIST)
5029                                         break;
5030                                 btrfs_drop_extent_cache(BTRFS_I(inode),
5031                                                         cur_offset,
5032                                                         cur_offset +
5033                                                         hole_size - 1, 0);
5034                         }
5035                         free_extent_map(hole_em);
5036                 }
5037 next:
5038                 free_extent_map(em);
5039                 em = NULL;
5040                 cur_offset = last_byte;
5041                 if (cur_offset >= block_end)
5042                         break;
5043         }
5044         free_extent_map(em);
5045         unlock_extent_cached(io_tree, hole_start, block_end - 1, &cached_state,
5046                              GFP_NOFS);
5047         return err;
5048 }
5049 
5050 static int btrfs_setsize(struct inode *inode, struct iattr *attr)
5051 {
5052         struct btrfs_root *root = BTRFS_I(inode)->root;
5053         struct btrfs_trans_handle *trans;
5054         loff_t oldsize = i_size_read(inode);
5055         loff_t newsize = attr->ia_size;
5056         int mask = attr->ia_valid;
5057         int ret;
5058 
5059         /*
5060          * The regular truncate() case without ATTR_CTIME and ATTR_MTIME is a
5061          * special case where we need to update the times despite not having
5062          * these flags set.  For all other operations the VFS set these flags
5063          * explicitly if it wants a timestamp update.
5064          */
5065         if (newsize != oldsize) {
5066                 inode_inc_iversion(inode);
5067                 if (!(mask & (ATTR_CTIME | ATTR_MTIME)))
5068                         inode->i_ctime = inode->i_mtime =
5069                                 current_time(inode);
5070         }
5071 
5072         if (newsize > oldsize) {
5073                 /*
5074                  * Don't do an expanding truncate while snapshotting is ongoing.
5075                  * This is to ensure the snapshot captures a fully consistent
5076                  * state of this file - if the snapshot captures this expanding
5077                  * truncation, it must capture all writes that happened before
5078                  * this truncation.
5079                  */
5080                 btrfs_wait_for_snapshot_creation(root);
5081                 ret = btrfs_cont_expand(inode, oldsize, newsize);
5082                 if (ret) {
5083                         btrfs_end_write_no_snapshotting(root);
5084                         return ret;
5085                 }
5086 
5087                 trans = btrfs_start_transaction(root, 1);
5088                 if (IS_ERR(trans)) {
5089                         btrfs_end_write_no_snapshotting(root);
5090                         return PTR_ERR(trans);
5091                 }
5092 
5093                 i_size_write(inode, newsize);
5094                 btrfs_ordered_update_i_size(inode, i_size_read(inode), NULL);
5095                 pagecache_isize_extended(inode, oldsize, newsize);
5096                 ret = btrfs_update_inode(trans, root, inode);
5097                 btrfs_end_write_no_snapshotting(root);
5098                 btrfs_end_transaction(trans);
5099         } else {
5100 
5101                 /*
5102                  * We're truncating a file that used to have good data down to
5103                  * zero. Make sure it gets into the ordered flush list so that
5104                  * any new writes get down to disk quickly.
5105                  */
5106                 if (newsize == 0)
5107                         set_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
5108                                 &BTRFS_I(inode)->runtime_flags);
5109 
5110                 /*
5111                  * 1 for the orphan item we're going to add
5112                  * 1 for the orphan item deletion.
5113                  */
5114                 trans = btrfs_start_transaction(root, 2);
5115                 if (IS_ERR(trans))
5116                         return PTR_ERR(trans);
5117 
5118                 /*
5119                  * We need to do this in case we fail at _any_ point during the
5120                  * actual truncate.  Once we do the truncate_setsize we could
5121                  * invalidate pages which forces any outstanding ordered io to
5122                  * be instantly completed which will give us extents that need
5123                  * to be truncated.  If we fail to get an orphan inode down we
5124                  * could have left over extents that were never meant to live,
5125                  * so we need to guarantee from this point on that everything
5126                  * will be consistent.
5127                  */
5128                 ret = btrfs_orphan_add(trans, BTRFS_I(inode));
5129                 btrfs_end_transaction(trans);
5130                 if (ret)
5131                         return ret;
5132 
5133                 /* we don't support swapfiles, so vmtruncate shouldn't fail */
5134                 truncate_setsize(inode, newsize);
5135 
5136                 /* Disable nonlocked read DIO to avoid the end less truncate */
5137                 btrfs_inode_block_unlocked_dio(BTRFS_I(inode));
5138                 inode_dio_wait(inode);
5139                 btrfs_inode_resume_unlocked_dio(BTRFS_I(inode));
5140 
5141                 ret = btrfs_truncate(inode);
5142                 if (ret && inode->i_nlink) {
5143                         int err;
5144 
5145                         /* To get a stable disk_i_size */
5146                         err = btrfs_wait_ordered_range(inode, 0, (u64)-1);
5147                         if (err) {
5148                                 btrfs_orphan_del(NULL, BTRFS_I(inode));
5149                                 return err;
5150                         }
5151 
5152                         /*
5153                          * failed to truncate, disk_i_size is only adjusted down
5154                          * as we remove extents, so it should represent the true
5155                          * size of the inode, so reset the in memory size and
5156                          * delete our orphan entry.
5157                          */
5158                         trans = btrfs_join_transaction(root);
5159                         if (IS_ERR(trans)) {
5160                                 btrfs_orphan_del(NULL, BTRFS_I(inode));
5161                                 return ret;
5162                         }
5163                         i_size_write(inode, BTRFS_I(inode)->disk_i_size);
5164                         err = btrfs_orphan_del(trans, BTRFS_I(inode));
5165                         if (err)
5166                                 btrfs_abort_transaction(trans, err);
5167                         btrfs_end_transaction(trans);
5168                 }
5169         }
5170 
5171         return ret;
5172 }
5173 
5174 static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
5175 {
5176         struct inode *inode = d_inode(dentry);
5177         struct btrfs_root *root = BTRFS_I(inode)->root;
5178         int err;
5179 
5180         if (btrfs_root_readonly(root))
5181                 return -EROFS;
5182 
5183         err = setattr_prepare(dentry, attr);
5184         if (err)
5185                 return err;
5186 
5187         if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
5188                 err = btrfs_setsize(inode, attr);
5189                 if (err)
5190                         return err;
5191         }
5192 
5193         if (attr->ia_valid) {
5194                 setattr_copy(inode, attr);
5195                 inode_inc_iversion(inode);
5196                 err = btrfs_dirty_inode(inode);
5197 
5198                 if (!err && attr->ia_valid & ATTR_MODE)
5199                         err = posix_acl_chmod(inode, inode->i_mode);
5200         }
5201 
5202         return err;
5203 }
5204 
5205 /*
5206  * While truncating the inode pages during eviction, we get the VFS calling
5207  * btrfs_invalidatepage() against each page of the inode. This is slow because
5208  * the calls to btrfs_invalidatepage() result in a huge amount of calls to
5209  * lock_extent_bits() and clear_extent_bit(), which keep merging and splitting
5210  * extent_state structures over and over, wasting lots of time.
5211  *
5212  * Therefore if the inode is being evicted, let btrfs_invalidatepage() skip all
5213  * those expensive operations on a per page basis and do only the ordered io
5214  * finishing, while we release here the extent_map and extent_state structures,
5215  * without the excessive merging and splitting.
5216  */
5217 static void evict_inode_truncate_pages(struct inode *inode)
5218 {
5219         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
5220         struct extent_map_tree *map_tree = &BTRFS_I(inode)->extent_tree;
5221         struct rb_node *node;
5222 
5223         ASSERT(inode->i_state & I_FREEING);
5224         truncate_inode_pages_final(&inode->i_data);
5225 
5226         write_lock(&map_tree->lock);
5227         while (!RB_EMPTY_ROOT(&map_tree->map)) {
5228                 struct extent_map *em;
5229 
5230                 node = rb_first(&map_tree->map);
5231                 em = rb_entry(node, struct extent_map, rb_node);
5232                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
5233                 clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
5234                 remove_extent_mapping(map_tree, em);
5235                 free_extent_map(em);
5236                 if (need_resched()) {
5237                         write_unlock(&map_tree->lock);
5238                         cond_resched();
5239                         write_lock(&map_tree->lock);
5240                 }
5241         }
5242         write_unlock(&map_tree->lock);
5243 
5244         /*
5245          * Keep looping until we have no more ranges in the io tree.
5246          * We can have ongoing bios started by readpages (called from readahead)
5247          * that have their endio callback (extent_io.c:end_bio_extent_readpage)
5248          * still in progress (unlocked the pages in the bio but did not yet
5249          * unlocked the ranges in the io tree). Therefore this means some
5250          * ranges can still be locked and eviction started because before
5251          * submitting those bios, which are executed by a separate task (work
5252          * queue kthread), inode references (inode->i_count) were not taken
5253          * (which would be dropped in the end io callback of each bio).
5254          * Therefore here we effectively end up waiting for those bios and
5255          * anyone else holding locked ranges without having bumped the inode's
5256          * reference count - if we don't do it, when they access the inode's
5257          * io_tree to unlock a range it may be too late, leading to an
5258          * use-after-free issue.
5259          */
5260         spin_lock(&io_tree->lock);
5261         while (!RB_EMPTY_ROOT(&io_tree->state)) {
5262                 struct extent_state *state;
5263                 struct extent_state *cached_state = NULL;
5264                 u64 start;
5265                 u64 end;
5266 
5267                 node = rb_first(&io_tree->state);
5268                 state = rb_entry(node, struct extent_state, rb_node);
5269                 start = state->start;
5270                 end = state->end;
5271                 spin_unlock(&io_tree->lock);
5272 
5273                 lock_extent_bits(io_tree, start, end, &cached_state);
5274 
5275                 /*
5276                  * If still has DELALLOC flag, the extent didn't reach disk,
5277                  * and its reserved space won't be freed by delayed_ref.
5278                  * So we need to free its reserved space here.
5279                  * (Refer to comment in btrfs_invalidatepage, case 2)
5280                  *
5281                  * Note, end is the bytenr of last byte, so we need + 1 here.
5282                  */
5283                 if (state->state & EXTENT_DELALLOC)
5284                         btrfs_qgroup_free_data(inode, NULL, start, end - start + 1);
5285 
5286                 clear_extent_bit(io_tree, start, end,
5287                                  EXTENT_LOCKED | EXTENT_DIRTY |
5288                                  EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
5289                                  EXTENT_DEFRAG, 1, 1,
5290                                  &cached_state, GFP_NOFS);
5291 
5292                 cond_resched();
5293                 spin_lock(&io_tree->lock);
5294         }
5295         spin_unlock(&io_tree->lock);
5296 }
5297 
5298 void btrfs_evict_inode(struct inode *inode)
5299 {
5300         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
5301         struct btrfs_trans_handle *trans;
5302         struct btrfs_root *root = BTRFS_I(inode)->root;
5303         struct btrfs_block_rsv *rsv, *global_rsv;
5304         int steal_from_global = 0;
5305         u64 min_size;
5306         int ret;
5307 
5308         trace_btrfs_inode_evict(inode);
5309 
5310         if (!root) {
5311                 kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
5312                 return;
5313         }
5314 
5315         min_size = btrfs_calc_trunc_metadata_size(fs_info, 1);
5316 
5317         evict_inode_truncate_pages(inode);
5318 
5319         if (inode->i_nlink &&
5320             ((btrfs_root_refs(&root->root_item) != 0 &&
5321               root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID) ||
5322              btrfs_is_free_space_inode(BTRFS_I(inode))))
5323                 goto no_delete;
5324 
5325         if (is_bad_inode(inode)) {
5326                 btrfs_orphan_del(NULL, BTRFS_I(inode));
5327                 goto no_delete;
5328         }
5329         /* do we really want it for ->i_nlink > 0 and zero btrfs_root_refs? */
5330         if (!special_file(inode->i_mode))
5331                 btrfs_wait_ordered_range(inode, 0, (u64)-1);
5332 
5333         btrfs_free_io_failure_record(BTRFS_I(inode), 0, (u64)-1);
5334 
5335         if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags)) {
5336                 BUG_ON(test_bit(BTRFS_INODE_HAS_ORPHAN_ITEM,
5337                                  &BTRFS_I(inode)->runtime_flags));
5338                 goto no_delete;
5339         }
5340 
5341         if (inode->i_nlink > 0) {
5342                 BUG_ON(btrfs_root_refs(&root->root_item) != 0 &&
5343                        root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID);
5344                 goto no_delete;
5345         }
5346 
5347         ret = btrfs_commit_inode_delayed_inode(BTRFS_I(inode));
5348         if (ret) {
5349                 btrfs_orphan_del(NULL, BTRFS_I(inode));
5350                 goto no_delete;
5351         }
5352 
5353         rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
5354         if (!rsv) {
5355                 btrfs_orphan_del(NULL, BTRFS_I(inode));
5356                 goto no_delete;
5357         }
5358         rsv->size = min_size;
5359         rsv->failfast = 1;
5360         global_rsv = &fs_info->global_block_rsv;
5361 
5362         btrfs_i_size_write(BTRFS_I(inode), 0);
5363 
5364         /*
5365          * This is a bit simpler than btrfs_truncate since we've already
5366          * reserved our space for our orphan item in the unlink, so we just
5367          * need to reserve some slack space in case we add bytes and update
5368          * inode item when doing the truncate.
5369          */
5370         while (1) {
5371                 ret = btrfs_block_rsv_refill(root, rsv, min_size,
5372                                              BTRFS_RESERVE_FLUSH_LIMIT);
5373 
5374                 /*
5375                  * Try and steal from the global reserve since we will
5376                  * likely not use this space anyway, we want to try as
5377                  * hard as possible to get this to work.
5378                  */
5379                 if (ret)
5380                         steal_from_global++;
5381                 else
5382                         steal_from_global = 0;
5383                 ret = 0;
5384 
5385                 /*
5386                  * steal_from_global == 0: we reserved stuff, hooray!
5387                  * steal_from_global == 1: we didn't reserve stuff, boo!
5388                  * steal_from_global == 2: we've committed, still not a lot of
5389                  * room but maybe we'll have room in the global reserve this
5390                  * time.
5391                  * steal_from_global == 3: abandon all hope!
5392                  */
5393                 if (steal_from_global > 2) {
5394                         btrfs_warn(fs_info,
5395                                    "Could not get space for a delete, will truncate on mount %d",
5396                                    ret);
5397                         btrfs_orphan_del(NULL, BTRFS_I(inode));
5398                         btrfs_free_block_rsv(fs_info, rsv);
5399                         goto no_delete;
5400                 }
5401 
5402                 trans = btrfs_join_transaction(root);
5403                 if (IS_ERR(trans)) {
5404                         btrfs_orphan_del(NULL, BTRFS_I(inode));
5405                         btrfs_free_block_rsv(fs_info, rsv);
5406                         goto no_delete;
5407                 }
5408 
5409                 /*
5410                  * We can't just steal from the global reserve, we need to make
5411                  * sure there is room to do it, if not we need to commit and try
5412                  * again.
5413                  */
5414                 if (steal_from_global) {
5415                         if (!btrfs_check_space_for_delayed_refs(trans, fs_info))
5416                                 ret = btrfs_block_rsv_migrate(global_rsv, rsv,
5417                                                               min_size, 0);
5418                         else
5419                                 ret = -ENOSPC;
5420                 }
5421 
5422                 /*
5423                  * Couldn't steal from the global reserve, we have too much
5424                  * pending stuff built up, commit the transaction and try it
5425                  * again.
5426                  */
5427                 if (ret) {
5428                         ret = btrfs_commit_transaction(trans);
5429                         if (ret) {
5430                                 btrfs_orphan_del(NULL, BTRFS_I(inode));
5431                                 btrfs_free_block_rsv(fs_info, rsv);
5432                                 goto no_delete;
5433                         }
5434                         continue;
5435                 } else {
5436                         steal_from_global = 0;
5437                 }
5438 
5439                 trans->block_rsv = rsv;
5440 
5441                 ret = btrfs_truncate_inode_items(trans, root, inode, 0, 0);
5442                 if (ret != -ENOSPC && ret != -EAGAIN)
5443                         break;
5444 
5445                 trans->block_rsv = &fs_info->trans_block_rsv;
5446                 btrfs_end_transaction(trans);
5447                 trans = NULL;
5448                 btrfs_btree_balance_dirty(fs_info);
5449         }
5450 
5451         btrfs_free_block_rsv(fs_info, rsv);
5452 
5453         /*
5454          * Errors here aren't a big deal, it just means we leave orphan items
5455          * in the tree.  They will be cleaned up on the next mount.
5456          */
5457         if (ret == 0) {
5458                 trans->block_rsv = root->orphan_block_rsv;
5459                 btrfs_orphan_del(trans, BTRFS_I(inode));
5460         } else {
5461                 btrfs_orphan_del(NULL, BTRFS_I(inode));
5462         }
5463 
5464         trans->block_rsv = &fs_info->trans_block_rsv;
5465         if (!(root == fs_info->tree_root ||
5466               root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID))
5467                 btrfs_return_ino(root, btrfs_ino(BTRFS_I(inode)));
5468 
5469         btrfs_end_transaction(trans);
5470         btrfs_btree_balance_dirty(fs_info);
5471 no_delete:
5472         btrfs_remove_delayed_node(BTRFS_I(inode));
5473         clear_inode(inode);
5474 }
5475 
5476 /*
5477  * this returns the key found in the dir entry in the location pointer.
5478  * If no dir entries were found, location->objectid is 0.
5479  */
5480 static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
5481                                struct btrfs_key *location)
5482 {
5483         const char *name = dentry->d_name.name;
5484         int namelen = dentry->d_name.len;
5485         struct btrfs_dir_item *di;
5486         struct btrfs_path *path;
5487         struct btrfs_root *root = BTRFS_I(dir)->root;
5488         int ret = 0;
5489 
5490         path = btrfs_alloc_path();
5491         if (!path)
5492                 return -ENOMEM;
5493 
5494         di = btrfs_lookup_dir_item(NULL, root, path, btrfs_ino(BTRFS_I(dir)),
5495                         name, namelen, 0);
5496         if (IS_ERR(di))
5497                 ret = PTR_ERR(di);
5498 
5499         if (IS_ERR_OR_NULL(di))
5500                 goto out_err;
5501 
5502         btrfs_dir_item_key_to_cpu(path->nodes[0], di, location);
5503 out:
5504         btrfs_free_path(path);
5505         return ret;
5506 out_err:
5507         location->objectid = 0;
5508         goto out;
5509 }
5510 
5511 /*
5512  * when we hit a tree root in a directory, the btrfs part of the inode
5513  * needs to be changed to reflect the root directory of the tree root.  This
5514  * is kind of like crossing a mount point.
5515  */
5516 static int fixup_tree_root_location(struct btrfs_fs_info *fs_info,
5517                                     struct inode *dir,
5518                                     struct dentry *dentry,
5519                                     struct btrfs_key *location,
5520                                     struct btrfs_root **sub_root)
5521 {
5522         struct btrfs_path *path;
5523         struct btrfs_root *new_root;
5524         struct btrfs_root_ref *ref;
5525         struct extent_buffer *leaf;
5526         struct btrfs_key key;
5527         int ret;
5528         int err = 0;
5529 
5530         path = btrfs_alloc_path();
5531         if (!path) {
5532                 err = -ENOMEM;
5533                 goto out;
5534         }
5535 
5536         err = -ENOENT;
5537         key.objectid = BTRFS_I(dir)->root->root_key.objectid;
5538         key.type = BTRFS_ROOT_REF_KEY;
5539         key.offset = location->objectid;
5540 
5541         ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
5542         if (ret) {
5543                 if (ret < 0)
5544                         err = ret;
5545                 goto out;
5546         }
5547 
5548         leaf = path->nodes[0];
5549         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
5550         if (btrfs_root_ref_dirid(leaf, ref) != btrfs_ino(BTRFS_I(dir)) ||
5551             btrfs_root_ref_name_len(leaf, ref) != dentry->d_name.len)
5552                 goto out;
5553 
5554         ret = memcmp_extent_buffer(leaf, dentry->d_name.name,
5555                                    (unsigned long)(ref + 1),
5556                                    dentry->d_name.len);
5557         if (ret)
5558                 goto out;
5559 
5560         btrfs_release_path(path);
5561 
5562         new_root = btrfs_read_fs_root_no_name(fs_info, location);
5563         if (IS_ERR(new_root)) {
5564                 err = PTR_ERR(new_root);
5565                 goto out;
5566         }
5567 
5568         *sub_root = new_root;
5569         location->objectid = btrfs_root_dirid(&new_root->root_item);
5570         location->type = BTRFS_INODE_ITEM_KEY;
5571         location->offset = 0;
5572         err = 0;
5573 out:
5574         btrfs_free_path(path);
5575         return err;
5576 }
5577 
5578 static void inode_tree_add(struct inode *inode)
5579 {
5580         struct btrfs_root *root = BTRFS_I(inode)->root;
5581         struct btrfs_inode *entry;
5582         struct rb_node **p;
5583         struct rb_node *parent;
5584         struct rb_node *new = &BTRFS_I(inode)->rb_node;
5585         u64 ino = btrfs_ino(BTRFS_I(inode));
5586 
5587         if (inode_unhashed(inode))
5588                 return;
5589         parent = NULL;
5590         spin_lock(&root->inode_lock);
5591         p = &root->inode_tree.rb_node;
5592         while (*p) {
5593                 parent = *p;
5594                 entry = rb_entry(parent, struct btrfs_inode, rb_node);
5595 
5596                 if (ino < btrfs_ino(BTRFS_I(&entry->vfs_inode)))
5597                         p = &parent->rb_left;
5598                 else if (ino > btrfs_ino(BTRFS_I(&entry->vfs_inode)))
5599                         p = &parent->rb_right;
5600                 else {
5601                         WARN_ON(!(entry->vfs_inode.i_state &
5602                                   (I_WILL_FREE | I_FREEING)));
5603                         rb_replace_node(parent, new, &root->inode_tree);
5604                         RB_CLEAR_NODE(parent);
5605                         spin_unlock(&root->inode_lock);
5606                         return;
5607                 }
5608         }
5609         rb_link_node(new, parent, p);
5610         rb_insert_color(new, &root->inode_tree);
5611         spin_unlock(&root->inode_lock);
5612 }
5613 
5614 static void inode_tree_del(struct inode *inode)
5615 {
5616         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
5617         struct btrfs_root *root = BTRFS_I(inode)->root;
5618         int empty = 0;
5619 
5620         spin_lock(&root->inode_lock);
5621         if (!RB_EMPTY_NODE(&BTRFS_I(inode)->rb_node)) {
5622                 rb_erase(&BTRFS_I(inode)->rb_node, &root->inode_tree);
5623                 RB_CLEAR_NODE(&BTRFS_I(inode)->rb_node);
5624                 empty = RB_EMPTY_ROOT(&root->inode_tree);
5625         }
5626         spin_unlock(&root->inode_lock);
5627 
5628         if (empty && btrfs_root_refs(&root->root_item) == 0) {
5629                 synchronize_srcu(&fs_info->subvol_srcu);
5630                 spin_lock(&root->inode_lock);
5631                 empty = RB_EMPTY_ROOT(&root->inode_tree);
5632                 spin_unlock(&root->inode_lock);
5633                 if (empty)
5634                         btrfs_add_dead_root(root);
5635         }
5636 }
5637 
5638 void btrfs_invalidate_inodes(struct btrfs_root *root)
5639 {
5640         struct btrfs_fs_info *fs_info = root->fs_info;
5641         struct rb_node *node;
5642         struct rb_node *prev;
5643         struct btrfs_inode *entry;
5644         struct inode *inode;
5645         u64 objectid = 0;
5646 
5647         if (!test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
5648                 WARN_ON(btrfs_root_refs(&root->root_item) != 0);
5649 
5650         spin_lock(&root->inode_lock);
5651 again:
5652         node = root->inode_tree.rb_node;
5653         prev = NULL;
5654         while (node) {
5655                 prev = node;
5656                 entry = rb_entry(node, struct btrfs_inode, rb_node);
5657 
5658                 if (objectid < btrfs_ino(BTRFS_I(&entry->vfs_inode)))
5659                         node = node->rb_left;
5660                 else if (objectid > btrfs_ino(BTRFS_I(&entry->vfs_inode)))
5661                         node = node->rb_right;
5662                 else
5663                         break;
5664         }
5665         if (!node) {
5666                 while (prev) {
5667                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
5668                         if (objectid <= btrfs_ino(BTRFS_I(&entry->vfs_inode))) {
5669                                 node = prev;
5670                                 break;
5671                         }
5672                         prev = rb_next(prev);
5673                 }
5674         }
5675         while (node) {
5676                 entry = rb_entry(node, struct btrfs_inode, rb_node);
5677                 objectid = btrfs_ino(BTRFS_I(&entry->vfs_inode)) + 1;
5678                 inode = igrab(&entry->vfs_inode);
5679                 if (inode) {
5680                         spin_unlock(&root->inode_lock);
5681                         if (atomic_read(&inode->i_count) > 1)
5682                                 d_prune_aliases(inode);
5683                         /*
5684                          * btrfs_drop_inode will have it removed from
5685                          * the inode cache when its usage count
5686                          * hits zero.
5687                          */
5688                         iput(inode);
5689                         cond_resched();
5690                         spin_lock(&root->inode_lock);
5691                         goto again;
5692                 }
5693 
5694                 if (cond_resched_lock(&root->inode_lock))
5695                         goto again;
5696 
5697                 node = rb_next(node);
5698         }
5699         spin_unlock(&root->inode_lock);
5700 }
5701 
5702 static int btrfs_init_locked_inode(struct inode *inode, void *p)
5703 {
5704         struct btrfs_iget_args *args = p;
5705         inode->i_ino = args->location->objectid;
5706         memcpy(&BTRFS_I(inode)->location, args->location,
5707                sizeof(*args->location));
5708         BTRFS_I(inode)->root = args->root;
5709         return 0;
5710 }
5711 
5712 static int btrfs_find_actor(struct inode *inode, void *opaque)
5713 {
5714         struct btrfs_iget_args *args = opaque;
5715         return args->location->objectid == BTRFS_I(inode)->location.objectid &&
5716                 args->root == BTRFS_I(inode)->root;
5717 }
5718 
5719 static struct inode *btrfs_iget_locked(struct super_block *s,
5720                                        struct btrfs_key *location,
5721                                        struct btrfs_root *root)
5722 {
5723         struct inode *inode;
5724         struct btrfs_iget_args args;
5725         unsigned long hashval = btrfs_inode_hash(location->objectid, root);
5726 
5727         args.location = location;
5728         args.root = root;
5729 
5730         inode = iget5_locked(s, hashval, btrfs_find_actor,
5731                              btrfs_init_locked_inode,
5732                              (void *)&args);
5733         return inode;
5734 }
5735 
5736 /* Get an inode object given its location and corresponding root.
5737  * Returns in *is_new if the inode was read from disk
5738  */
5739 struct inode *btrfs_iget(struct super_block *s, struct btrfs_key *location,
5740                          struct btrfs_root *root, int *new)
5741 {
5742         struct inode *inode;
5743 
5744         inode = btrfs_iget_locked(s, location, root);
5745         if (!inode)
5746                 return ERR_PTR(-ENOMEM);
5747 
5748         if (inode->i_state & I_NEW) {
5749                 int ret;
5750 
5751                 ret = btrfs_read_locked_inode(inode);
5752                 if (!is_bad_inode(inode)) {
5753                         inode_tree_add(inode);
5754                         unlock_new_inode(inode);
5755                         if (new)
5756                                 *new = 1;
5757                 } else {
5758                         unlock_new_inode(inode);
5759                         iput(inode);
5760                         ASSERT(ret < 0);
5761                         inode = ERR_PTR(ret < 0 ? ret : -ESTALE);
5762                 }
5763         }
5764 
5765         return inode;
5766 }
5767 
5768 static struct inode *new_simple_dir(struct super_block *s,
5769                                     struct btrfs_key *key,
5770                                     struct btrfs_root *root)
5771 {
5772         struct inode *inode = new_inode(s);
5773 
5774         if (!inode)
5775                 return ERR_PTR(-ENOMEM);
5776 
5777         BTRFS_I(inode)->root = root;
5778         memcpy(&BTRFS_I(inode)->location, key, sizeof(*key));
5779         set_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags);
5780 
5781         inode->i_ino = BTRFS_EMPTY_SUBVOL_DIR_OBJECTID;
5782         inode->i_op = &btrfs_dir_ro_inode_operations;
5783         inode->i_opflags &= ~IOP_XATTR;
5784         inode->i_fop = &simple_dir_operations;
5785         inode->i_mode = S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO;
5786         inode->i_mtime = current_time(inode);
5787         inode->i_atime = inode->i_mtime;
5788         inode->i_ctime = inode->i_mtime;
5789         BTRFS_I(inode)->i_otime = inode->i_mtime;
5790 
5791         return inode;
5792 }
5793 
5794 struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
5795 {
5796         struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
5797         struct inode *inode;
5798         struct btrfs_root *root = BTRFS_I(dir)->root;
5799         struct btrfs_root *sub_root = root;
5800         struct btrfs_key location;
5801         int index;
5802         int ret = 0;
5803 
5804         if (dentry->d_name.len > BTRFS_NAME_LEN)
5805                 return ERR_PTR(-ENAMETOOLONG);
5806 
5807         ret = btrfs_inode_by_name(dir, dentry, &location);
5808         if (ret < 0)
5809                 return ERR_PTR(ret);
5810 
5811         if (location.objectid == 0)
5812                 return ERR_PTR(-ENOENT);
5813 
5814         if (location.type == BTRFS_INODE_ITEM_KEY) {
5815                 inode = btrfs_iget(dir->i_sb, &location, root, NULL);
5816                 return inode;
5817         }
5818 
5819         BUG_ON(location.type != BTRFS_ROOT_ITEM_KEY);
5820 
5821         index = srcu_read_lock(&fs_info->subvol_srcu);
5822         ret = fixup_tree_root_location(fs_info, dir, dentry,
5823                                        &location, &sub_root);
5824         if (ret < 0) {
5825                 if (ret != -ENOENT)
5826                         inode = ERR_PTR(ret);
5827                 else
5828                         inode = new_simple_dir(dir->i_sb, &location, sub_root);
5829         } else {
5830                 inode = btrfs_iget(dir->i_sb, &location, sub_root, NULL);
5831         }
5832         srcu_read_unlock(&fs_info->subvol_srcu, index);
5833 
5834         if (!IS_ERR(inode) && root != sub_root) {
5835                 down_read(&fs_info->cleanup_work_sem);
5836                 if (!sb_rdonly(inode->i_sb))
5837                         ret = btrfs_orphan_cleanup(sub_root);
5838                 up_read(&fs_info->cleanup_work_sem);
5839                 if (ret) {
5840                         iput(inode);
5841                         inode = ERR_PTR(ret);
5842                 }
5843         }
5844 
5845         return inode;
5846 }
5847 
5848 static int btrfs_dentry_delete(const struct dentry *dentry)
5849 {
5850         struct btrfs_root *root;
5851         struct inode *inode = d_inode(dentry);
5852 
5853         if (!inode && !IS_ROOT(dentry))
5854                 inode = d_inode(dentry->d_parent);
5855 
5856         if (inode) {
5857                 root = BTRFS_I(inode)->root;
5858                 if (btrfs_root_refs(&root->root_item) == 0)
5859                         return 1;
5860 
5861                 if (btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)
5862                         return 1;
5863         }
5864         return 0;
5865 }
5866 
5867 static void btrfs_dentry_release(struct dentry *dentry)
5868 {
5869         kfree(dentry->d_fsdata);
5870 }
5871 
5872 static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
5873                                    unsigned int flags)
5874 {
5875         struct inode *inode;
5876 
5877         inode = btrfs_lookup_dentry(dir, dentry);
5878         if (IS_ERR(inode)) {
5879                 if (PTR_ERR(inode) == -ENOENT)
5880                         inode = NULL;
5881                 else
5882                         return ERR_CAST(inode);
5883         }
5884 
5885         return d_splice_alias(inode, dentry);
5886 }
5887 
5888 unsigned char btrfs_filetype_table[] = {
5889         DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
5890 };
5891 
5892 /*
5893  * All this infrastructure exists because dir_emit can fault, and we are holding
5894  * the tree lock when doing readdir.  For now just allocate a buffer and copy
5895  * our information into that, and then dir_emit from the buffer.  This is
5896  * similar to what NFS does, only we don't keep the buffer around in pagecache
5897  * because I'm afraid I'll mess that up.  Long term we need to make filldir do
5898  * copy_to_user_inatomic so we don't have to worry about page faulting under the
5899  * tree lock.
5900  */
5901 static int btrfs_opendir(struct inode *inode, struct file *file)
5902 {
5903         struct btrfs_file_private *private;
5904 
5905         private = kzalloc(sizeof(struct btrfs_file_private), GFP_KERNEL);
5906         if (!private)
5907                 return -ENOMEM;
5908         private->filldir_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
5909         if (!private->filldir_buf) {
5910                 kfree(private);
5911                 return -ENOMEM;
5912         }
5913         file->private_data = private;
5914         return 0;
5915 }
5916 
5917 struct dir_entry {
5918         u64 ino;
5919         u64 offset;
5920         unsigned type;
5921         int name_len;
5922 };
5923 
5924 static int btrfs_filldir(void *addr, int entries, struct dir_context *ctx)
5925 {
5926         while (entries--) {
5927                 struct dir_entry *entry = addr;
5928                 char *name = (char *)(entry + 1);
5929 
5930                 ctx->pos = entry->offset;
5931                 if (!dir_emit(ctx, name, entry->name_len, entry->ino,
5932                               entry->type))
5933                         return 1;
5934                 addr += sizeof(struct dir_entry) + entry->name_len;
5935                 ctx->pos++;
5936         }
5937         return 0;
5938 }
5939 
5940 static int btrfs_real_readdir(struct file *file, struct dir_context *ctx)
5941 {
5942         struct inode *inode = file_inode(file);
5943         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
5944         struct btrfs_root *root = BTRFS_I(inode)->root;
5945         struct btrfs_file_private *private = file->private_data;
5946         struct btrfs_dir_item *di;
5947         struct btrfs_key key;
5948         struct btrfs_key found_key;
5949         struct btrfs_path *path;
5950         void *addr;
5951         struct list_head ins_list;
5952         struct list_head del_list;
5953         int ret;
5954         struct extent_buffer *leaf;
5955         int slot;
5956         char *name_ptr;
5957         int name_len;
5958         int entries = 0;
5959         int total_len = 0;
5960         bool put = false;
5961         struct btrfs_key location;
5962 
5963         if (!dir_emit_dots(file, ctx))
5964                 return 0;
5965 
5966         path = btrfs_alloc_path();
5967         if (!path)
5968                 return -ENOMEM;
5969 
5970         addr = private->filldir_buf;
5971         path->reada = READA_FORWARD;
5972 
5973         INIT_LIST_HEAD(&ins_list);
5974         INIT_LIST_HEAD(&del_list);
5975         put = btrfs_readdir_get_delayed_items(inode, &ins_list, &del_list);
5976 
5977 again:
5978         key.type = BTRFS_DIR_INDEX_KEY;
5979         key.offset = ctx->pos;
5980         key.objectid = btrfs_ino(BTRFS_I(inode));
5981 
5982         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5983         if (ret < 0)
5984                 goto err;
5985 
5986         while (1) {
5987                 struct dir_entry *entry;
5988 
5989                 leaf = path->nodes[0];
5990                 slot = path->slots[0];
5991                 if (slot >= btrfs_header_nritems(leaf)) {
5992                         ret = btrfs_next_leaf(root, path);
5993                         if (ret < 0)
5994                                 goto err;
5995                         else if (ret > 0)
5996                                 break;
5997                         continue;
5998                 }
5999 
6000                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
6001 
6002                 if (found_key.objectid != key.objectid)
6003                         break;
6004                 if (found_key.type != BTRFS_DIR_INDEX_KEY)
6005                         break;
6006                 if (found_key.offset < ctx->pos)
6007                         goto next;
6008                 if (btrfs_should_delete_dir_index(&del_list, found_key.offset))
6009                         goto next;
6010                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
6011                 if (verify_dir_item(fs_info, leaf, slot, di))
6012                         goto next;
6013 
6014                 name_len = btrfs_dir_name_len(leaf, di);
6015                 if ((total_len + sizeof(struct dir_entry) + name_len) >=
6016                     PAGE_SIZE) {
6017                         btrfs_release_path(path);
6018                         ret = btrfs_filldir(private->filldir_buf, entries, ctx);
6019                         if (ret)
6020                                 goto nopos;
6021                         addr = private->filldir_buf;
6022                         entries = 0;
6023                         total_len = 0;
6024                         goto again;
6025                 }
6026 
6027                 entry = addr;
6028                 entry->name_len = name_len;
6029                 name_ptr = (char *)(entry + 1);
6030                 read_extent_buffer(leaf, name_ptr, (unsigned long)(di + 1),
6031                                    name_len);
6032                 entry->type = btrfs_filetype_table[btrfs_dir_type(leaf, di)];
6033                 btrfs_dir_item_key_to_cpu(leaf, di, &location);
6034                 entry->ino = location.objectid;
6035                 entry->offset = found_key.offset;
6036                 entries++;
6037                 addr += sizeof(struct dir_entry) + name_len;
6038                 total_len += sizeof(struct dir_entry) + name_len;
6039 next:
6040                 path->slots[0]++;
6041         }
6042         btrfs_release_path(path);
6043 
6044         ret = btrfs_filldir(private->filldir_buf, entries, ctx);
6045         if (ret)
6046                 goto nopos;
6047 
6048         ret = btrfs_readdir_delayed_dir_index(ctx, &ins_list);
6049         if (ret)
6050                 goto nopos;
6051 
6052         /*
6053          * Stop new entries from being returned after we return the last
6054          * entry.
6055          *
6056          * New directory entries are assigned a strictly increasing
6057          * offset.  This means that new entries created during readdir
6058          * are *guaranteed* to be seen in the future by that readdir.
6059          * This has broken buggy programs which operate on names as
6060          * they're returned by readdir.  Until we re-use freed offsets
6061          * we have this hack to stop new entries from being returned
6062          * under the assumption that they'll never reach this huge
6063          * offset.
6064          *
6065          * This is being careful not to overflow 32bit loff_t unless the
6066          * last entry requires it because doing so has broken 32bit apps
6067          * in the past.
6068          */
6069         if (ctx->pos >= INT_MAX)
6070                 ctx->pos = LLONG_MAX;
6071         else
6072                 ctx->pos = INT_MAX;
6073 nopos:
6074         ret = 0;
6075 err:
6076         if (put)
6077                 btrfs_readdir_put_delayed_items(inode, &ins_list, &del_list);
6078         btrfs_free_path(path);
6079         return ret;
6080 }
6081 
6082 int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc)
6083 {
6084         struct btrfs_root *root = BTRFS_I(inode)->root;
6085         struct btrfs_trans_handle *trans;
6086         int ret = 0;
6087         bool nolock = false;
6088 
6089         if (test_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags))
6090                 return 0;
6091 
6092         if (btrfs_fs_closing(root->fs_info) &&
6093                         btrfs_is_free_space_inode(BTRFS_I(inode)))
6094                 nolock = true;
6095 
6096         if (wbc->sync_mode == WB_SYNC_ALL) {
6097                 if (nolock)
6098                         trans = btrfs_join_transaction_nolock(root);
6099                 else
6100                         trans = btrfs_join_transaction(root);
6101                 if (IS_ERR(trans))
6102                         return PTR_ERR(trans);
6103                 ret = btrfs_commit_transaction(trans);
6104         }
6105         return ret;
6106 }
6107 
6108 /*
6109  * This is somewhat expensive, updating the tree every time the
6110  * inode changes.  But, it is most likely to find the inode in cache.
6111  * FIXME, needs more benchmarking...there are no reasons other than performance
6112  * to keep or drop this code.
6113  */
6114 static int btrfs_dirty_inode(struct inode *inode)
6115 {
6116         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
6117         struct btrfs_root *root = BTRFS_I(inode)->root;
6118         struct btrfs_trans_handle *trans;
6119         int ret;
6120 
6121         if (test_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags))
6122                 return 0;
6123 
6124         trans = btrfs_join_transaction(root);
6125         if (IS_ERR(trans))
6126                 return PTR_ERR(trans);
6127 
6128         ret = btrfs_update_inode(trans, root, inode);
6129         if (ret && ret == -ENOSPC) {
6130                 /* whoops, lets try again with the full transaction */
6131                 btrfs_end_transaction(trans);
6132                 trans = btrfs_start_transaction(root, 1);
6133                 if (IS_ERR(trans))
6134                         return PTR_ERR(trans);
6135 
6136                 ret = btrfs_update_inode(trans, root, inode);
6137         }
6138         btrfs_end_transaction(trans);
6139         if (BTRFS_I(inode)->delayed_node)
6140                 btrfs_balance_delayed_items(fs_info);
6141 
6142         return ret;
6143 }
6144 
6145 /*
6146  * This is a copy of file_update_time.  We need this so we can return error on
6147  * ENOSPC for updating the inode in the case of file write and mmap writes.
6148  */
6149 static int btrfs_update_time(struct inode *inode, struct timespec *now,
6150                              int flags)
6151 {
6152         struct btrfs_root *root = BTRFS_I(inode)->root;
6153 
6154         if (btrfs_root_readonly(root))
6155                 return -EROFS;
6156 
6157         if (flags & S_VERSION)
6158                 inode_inc_iversion(inode);
6159         if (flags & S_CTIME)
6160                 inode->i_ctime = *now;
6161         if (flags & S_MTIME)
6162                 inode->i_mtime = *now;
6163         if (flags & S_ATIME)
6164                 inode->i_atime = *now;
6165         return btrfs_dirty_inode(inode);
6166 }
6167 
6168 /*
6169  * find the highest existing sequence number in a directory
6170  * and then set the in-memory index_cnt variable to reflect
6171  * free sequence numbers
6172  */
6173 static int btrfs_set_inode_index_count(struct btrfs_inode *inode)
6174 {
6175         struct btrfs_root *root = inode->root;
6176         struct btrfs_key key, found_key;
6177         struct btrfs_path *path;
6178         struct extent_buffer *leaf;
6179         int ret;
6180 
6181         key.objectid = btrfs_ino(inode);
6182         key.type = BTRFS_DIR_INDEX_KEY;
6183         key.offset = (u64)-1;
6184 
6185         path = btrfs_alloc_path();
6186         if (!path)
6187                 return -ENOMEM;
6188 
6189         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
6190         if (ret < 0)
6191                 goto out;
6192         /* FIXME: we should be able to handle this */
6193         if (ret == 0)
6194                 goto out;
6195         ret = 0;
6196 
6197         /*
6198          * MAGIC NUMBER EXPLANATION:
6199          * since we search a directory based on f_pos we have to start at 2
6200          * since '.' and '..' have f_pos of 0 and 1 respectively, so everybody
6201          * else has to start at 2
6202          */
6203         if (path->slots[0] == 0) {
6204                 inode->index_cnt = 2;
6205                 goto out;
6206         }
6207 
6208         path->slots[0]--;
6209 
6210         leaf = path->nodes[0];
6211         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
6212 
6213         if (found_key.objectid != btrfs_ino(inode) ||
6214             found_key.type != BTRFS_DIR_INDEX_KEY) {
6215                 inode->index_cnt = 2;
6216                 goto out;
6217         }
6218 
6219         inode->index_cnt = found_key.offset + 1;
6220 out:
6221         btrfs_free_path(path);
6222         return ret;
6223 }
6224 
6225 /*
6226  * helper to find a free sequence number in a given directory.  This current
6227  * code is very simple, later versions will do smarter things in the btree
6228  */
6229 int btrfs_set_inode_index(struct btrfs_inode *dir, u64 *index)
6230 {
6231         int ret = 0;
6232 
6233         if (dir->index_cnt == (u64)-1) {
6234                 ret = btrfs_inode_delayed_dir_index_count(dir);
6235                 if (ret) {
6236                         ret = btrfs_set_inode_index_count(dir);
6237                         if (ret)
6238                                 return ret;
6239                 }
6240         }
6241 
6242         *index = dir->index_cnt;
6243         dir->index_cnt++;
6244 
6245         return ret;
6246 }
6247 
6248 static int btrfs_insert_inode_locked(struct inode *inode)
6249 {
6250         struct btrfs_iget_args args;
6251         args.location = &BTRFS_I(inode)->location;
6252         args.root = BTRFS_I(inode)->root;
6253 
6254         return insert_inode_locked4(inode,
6255                    btrfs_inode_hash(inode->i_ino, BTRFS_I(inode)->root),
6256                    btrfs_find_actor, &args);
6257 }
6258 
6259 /*
6260  * Inherit flags from the parent inode.
6261  *
6262  * Currently only the compression flags and the cow flags are inherited.
6263  */
6264 static void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
6265 {
6266         unsigned int flags;
6267 
6268         if (!dir)
6269                 return;
6270 
6271         flags = BTRFS_I(dir)->flags;
6272 
6273         if (flags & BTRFS_INODE_NOCOMPRESS) {
6274                 BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
6275                 BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
6276         } else if (flags & BTRFS_INODE_COMPRESS) {
6277                 BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
6278                 BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
6279         }
6280 
6281         if (flags & BTRFS_INODE_NODATACOW) {
6282                 BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
6283                 if (S_ISREG(inode->i_mode))
6284                         BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
6285         }
6286 
6287         btrfs_update_iflags(inode);
6288 }
6289 
6290 static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
6291                                      struct btrfs_root *root,
6292                                      struct inode *dir,
6293                                      const char *name, int name_len,
6294                                      u64 ref_objectid, u64 objectid,
6295                                      umode_t mode, u64 *index)
6296 {
6297         struct btrfs_fs_info *fs_info = root->fs_info;
6298         struct inode *inode;
6299         struct btrfs_inode_item *inode_item;
6300         struct btrfs_key *location;
6301         struct btrfs_path *path;
6302         struct btrfs_inode_ref *ref;
6303         struct btrfs_key key[2];
6304         u32 sizes[2];
6305         int nitems = name ? 2 : 1;
6306         unsigned long ptr;
6307         int ret;
6308 
6309         path = btrfs_alloc_path();
6310         if (!path)
6311                 return ERR_PTR(-ENOMEM);
6312 
6313         inode = new_inode(fs_info->sb);
6314         if (!inode) {
6315                 btrfs_free_path(path);
6316                 return ERR_PTR(-ENOMEM);
6317         }
6318 
6319         /*
6320          * O_TMPFILE, set link count to 0, so that after this point,
6321          * we fill in an inode item with the correct link count.
6322          */
6323         if (!name)
6324                 set_nlink(inode, 0);
6325 
6326         /*
6327          * we have to initialize this early, so we can reclaim the inode
6328          * number if we fail afterwards in this function.
6329          */
6330         inode->i_ino = objectid;
6331 
6332         if (dir && name) {
6333                 trace_btrfs_inode_request(dir);
6334 
6335                 ret = btrfs_set_inode_index(BTRFS_I(dir), index);
6336                 if (ret) {
6337                         btrfs_free_path(path);
6338                         iput(inode);
6339                         return ERR_PTR(ret);
6340                 }
6341         } else if (dir) {
6342                 *index = 0;
6343         }
6344         /*
6345          * index_cnt is ignored for everything but a dir,
6346          * btrfs_get_inode_index_count has an explanation for the magic
6347          * number
6348          */
6349         BTRFS_I(inode)->index_cnt = 2;
6350         BTRFS_I(inode)->dir_index = *index;
6351         BTRFS_I(inode)->root = root;
6352         BTRFS_I(inode)->generation = trans->transid;
6353         inode->i_generation = BTRFS_I(inode)->generation;
6354 
6355         /*
6356          * We could have gotten an inode number from somebody who was fsynced
6357          * and then removed in this same transaction, so let's just set full
6358          * sync since it will be a full sync anyway and this will blow away the
6359          * old info in the log.
6360          */
6361         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(inode)->runtime_flags);
6362 
6363         key[0].objectid = objectid;
6364         key[0].type = BTRFS_INODE_ITEM_KEY;
6365         key[0].offset = 0;
6366 
6367         sizes[0] = sizeof(struct btrfs_inode_item);
6368 
6369         if (name) {
6370                 /*
6371                  * Start new inodes with an inode_ref. This is slightly more
6372                  * efficient for small numbers of hard links since they will
6373                  * be packed into one item. Extended refs will kick in if we
6374                  * add more hard links than can fit in the ref item.
6375                  */
6376                 key[1].objectid = objectid;
6377                 key[1].type = BTRFS_INODE_REF_KEY;
6378                 key[1].offset = ref_objectid;
6379 
6380                 sizes[1] = name_len + sizeof(*ref);
6381         }
6382 
6383         location = &BTRFS_I(inode)->location;
6384         location->objectid = objectid;
6385         location->offset = 0;
6386         location->type = BTRFS_INODE_ITEM_KEY;
6387 
6388         ret = btrfs_insert_inode_locked(inode);
6389         if (ret < 0)
6390                 goto fail;
6391 
6392         path->leave_spinning = 1;
6393         ret = btrfs_insert_empty_items(trans, root, path, key, sizes, nitems);
6394         if (ret != 0)
6395                 goto fail_unlock;
6396 
6397         inode_init_owner(inode, dir, mode);
6398         inode_set_bytes(inode, 0);
6399 
6400         inode->i_mtime = current_time(inode);
6401         inode->i_atime = inode->i_mtime;
6402         inode->i_ctime = inode->i_mtime;
6403         BTRFS_I(inode)->i_otime = inode->i_mtime;
6404 
6405         inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
6406                                   struct btrfs_inode_item);
6407         memzero_extent_buffer(path->nodes[0], (unsigned long)inode_item,
6408                              sizeof(*inode_item));
6409         fill_inode_item(trans, path->nodes[0], inode_item, inode);
6410 
6411         if (name) {
6412                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0] + 1,
6413                                      struct btrfs_inode_ref);
6414                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
6415                 btrfs_set_inode_ref_index(path->nodes[0], ref, *index);
6416                 ptr = (unsigned long)(ref + 1);
6417                 write_extent_buffer(path->nodes[0], name, ptr, name_len);
6418         }
6419 
6420         btrfs_mark_buffer_dirty(path->nodes[0]);
6421         btrfs_free_path(path);
6422 
6423         btrfs_inherit_iflags(inode, dir);
6424 
6425         if (S_ISREG(mode)) {
6426                 if (btrfs_test_opt(fs_info, NODATASUM))
6427                         BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
6428                 if (btrfs_test_opt(fs_info, NODATACOW))
6429                         BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW |
6430                                 BTRFS_INODE_NODATASUM;
6431         }
6432 
6433         inode_tree_add(inode);
6434 
6435         trace_btrfs_inode_new(inode);
6436         btrfs_set_inode_last_trans(trans, inode);
6437 
6438         btrfs_update_root_times(trans, root);
6439 
6440         ret = btrfs_inode_inherit_props(trans, inode, dir);
6441         if (ret)
6442                 btrfs_err(fs_info,
6443                           "error inheriting props for ino %llu (root %llu): %d",
6444                         btrfs_ino(BTRFS_I(inode)), root->root_key.objectid, ret);
6445 
6446         return inode;
6447 
6448 fail_unlock:
6449         unlock_new_inode(inode);
6450 fail:
6451         if (dir && name)
6452                 BTRFS_I(dir)->index_cnt--;
6453         btrfs_free_path(path);
6454         iput(inode);
6455         return ERR_PTR(ret);
6456 }
6457 
6458 static inline u8 btrfs_inode_type(struct inode *inode)
6459 {
6460         return btrfs_type_by_mode[(inode->i_mode & S_IFMT) >> S_SHIFT];
6461 }
6462 
6463 /*
6464  * utility function to add 'inode' into 'parent_inode' with
6465  * a give name and a given sequence number.
6466  * if 'add_backref' is true, also insert a backref from the
6467  * inode to the parent directory.
6468  */
6469 int btrfs_add_link(struct btrfs_trans_handle *trans,
6470                    struct btrfs_inode *parent_inode, struct btrfs_inode *inode,
6471                    const char *name, int name_len, int add_backref, u64 index)
6472 {
6473         struct btrfs_fs_info *fs_info = btrfs_sb(inode->vfs_inode.i_sb);
6474         int ret = 0;
6475         struct btrfs_key key;
6476         struct btrfs_root *root = parent_inode->root;
6477         u64 ino = btrfs_ino(inode);
6478         u64 parent_ino = btrfs_ino(parent_inode);
6479 
6480         if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
6481                 memcpy(&key, &inode->root->root_key, sizeof(key));
6482         } else {
6483                 key.objectid = ino;
6484                 key.type = BTRFS_INODE_ITEM_KEY;
6485                 key.offset = 0;
6486         }
6487 
6488         if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
6489                 ret = btrfs_add_root_ref(trans, fs_info, key.objectid,
6490                                          root->root_key.objectid, parent_ino,
6491                                          index, name, name_len);
6492         } else if (add_backref) {
6493                 ret = btrfs_insert_inode_ref(trans, root, name, name_len, ino,
6494                                              parent_ino, index);
6495         }
6496 
6497         /* Nothing to clean up yet */
6498         if (ret)
6499                 return ret;
6500 
6501         ret = btrfs_insert_dir_item(trans, root, name, name_len,
6502                                     parent_inode, &key,
6503                                     btrfs_inode_type(&inode->vfs_inode), index);
6504         if (ret == -EEXIST || ret == -EOVERFLOW)
6505                 goto fail_dir_item;
6506         else if (ret) {
6507                 btrfs_abort_transaction(trans, ret);
6508                 return ret;
6509         }
6510 
6511         btrfs_i_size_write(parent_inode, parent_inode->vfs_inode.i_size +
6512                            name_len * 2);
6513         inode_inc_iversion(&parent_inode->vfs_inode);
6514         parent_inode->vfs_inode.i_mtime = parent_inode->vfs_inode.i_ctime =
6515                 current_time(&parent_inode->vfs_inode);
6516         ret = btrfs_update_inode(trans, root, &parent_inode->vfs_inode);
6517         if (ret)
6518                 btrfs_abort_transaction(trans, ret);
6519         return ret;
6520 
6521 fail_dir_item:
6522         if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
6523                 u64 local_index;
6524                 int err;
6525                 err = btrfs_del_root_ref(trans, fs_info, key.objectid,
6526                                          root->root_key.objectid, parent_ino,
6527                                          &local_index, name, name_len);
6528 
6529         } else if (add_backref) {
6530                 u64 local_index;
6531                 int err;
6532 
6533                 err = btrfs_del_inode_ref(trans, root, name, name_len,
6534                                           ino, parent_ino, &local_index);
6535         }
6536         return ret;
6537 }
6538 
6539 static int btrfs_add_nondir(struct btrfs_trans_handle *trans,
6540                             struct btrfs_inode *dir, struct dentry *dentry,
6541                             struct btrfs_inode *inode, int backref, u64 index)
6542 {
6543         int err = btrfs_add_link(trans, dir, inode,
6544                                  dentry->d_name.name, dentry->d_name.len,
6545                                  backref, index);
6546         if (err > 0)
6547                 err = -EEXIST;
6548         return err;
6549 }
6550 
6551 static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
6552                         umode_t mode, dev_t rdev)
6553 {
6554         struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
6555         struct btrfs_trans_handle *trans;
6556         struct btrfs_root *root = BTRFS_I(dir)->root;
6557         struct inode *inode = NULL;
6558         int err;
6559         int drop_inode = 0;
6560         u64 objectid;
6561         u64 index = 0;
6562 
6563         /*
6564          * 2 for inode item and ref
6565          * 2 for dir items
6566          * 1 for xattr if selinux is on
6567          */
6568         trans = btrfs_start_transaction(root, 5);
6569         if (IS_ERR(trans))
6570                 return PTR_ERR(trans);
6571 
6572         err = btrfs_find_free_ino(root, &objectid);
6573         if (err)
6574                 goto out_unlock;
6575 
6576         inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
6577                         dentry->d_name.len, btrfs_ino(BTRFS_I(dir)), objectid,
6578                         mode, &index);
6579         if (IS_ERR(inode)) {
6580                 err = PTR_ERR(inode);
6581                 goto out_unlock;
6582         }
6583 
6584         /*
6585         * If the active LSM wants to access the inode during
6586         * d_instantiate it needs these. Smack checks to see
6587         * if the filesystem supports xattrs by looking at the
6588         * ops vector.
6589         */
6590         inode->i_op = &btrfs_special_inode_operations;
6591         init_special_inode(inode, inode->i_mode, rdev);
6592 
6593         err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
6594         if (err)
6595                 goto out_unlock_inode;
6596 
6597         err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry, BTRFS_I(inode),
6598                         0, index);
6599         if (err) {
6600                 goto out_unlock_inode;
6601         } else {
6602                 btrfs_update_inode(trans, root, inode);
6603                 unlock_new_inode(inode);
6604                 d_instantiate(dentry, inode);
6605         }
6606 
6607 out_unlock:
6608         btrfs_end_transaction(trans);
6609         btrfs_balance_delayed_items(fs_info);
6610         btrfs_btree_balance_dirty(fs_info);
6611         if (drop_inode) {
6612                 inode_dec_link_count(inode);
6613                 iput(inode);
6614         }
6615         return err;
6616 
6617 out_unlock_inode:
6618         drop_inode = 1;
6619         unlock_new_inode(inode);
6620         goto out_unlock;
6621 
6622 }
6623 
6624 static int btrfs_create(struct inode *dir, struct dentry *dentry,
6625                         umode_t mode, bool excl)
6626 {
6627         struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
6628         struct btrfs_trans_handle *trans;
6629         struct btrfs_root *root = BTRFS_I(dir)->root;
6630         struct inode *inode = NULL;
6631         int drop_inode_on_err = 0;
6632         int err;
6633         u64 objectid;
6634         u64 index = 0;
6635 
6636         /*
6637          * 2 for inode item and ref
6638          * 2 for dir items
6639          * 1 for xattr if selinux is on
6640          */
6641         trans = btrfs_start_transaction(root, 5);
6642         if (IS_ERR(trans))
6643                 return PTR_ERR(trans);
6644 
6645         err = btrfs_find_free_ino(root, &objectid);
6646         if (err)
6647                 goto out_unlock;
6648 
6649         inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
6650                         dentry->d_name.len, btrfs_ino(BTRFS_I(dir)), objectid,
6651                         mode, &index);
6652         if (IS_ERR(inode)) {
6653                 err = PTR_ERR(inode);
6654                 goto out_unlock;
6655         }
6656         drop_inode_on_err = 1;
6657         /*
6658         * If the active LSM wants to access the inode during
6659         * d_instantiate it needs these. Smack checks to see
6660         * if the filesystem supports xattrs by looking at the
6661         * ops vector.
6662         */
6663         inode->i_fop = &btrfs_file_operations;
6664         inode->i_op = &btrfs_file_inode_operations;
6665         inode->i_mapping->a_ops = &btrfs_aops;
6666 
6667         err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
6668         if (err)
6669                 goto out_unlock_inode;
6670 
6671         err = btrfs_update_inode(trans, root, inode);
6672         if (err)
6673                 goto out_unlock_inode;
6674 
6675         err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry, BTRFS_I(inode),
6676                         0, index);
6677         if (err)
6678                 goto out_unlock_inode;
6679 
6680         BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
6681         unlock_new_inode(inode);
6682         d_instantiate(dentry, inode);
6683 
6684 out_unlock:
6685         btrfs_end_transaction(trans);
6686         if (err && drop_inode_on_err) {
6687                 inode_dec_link_count(inode);
6688                 iput(inode);
6689         }
6690         btrfs_balance_delayed_items(fs_info);
6691         btrfs_btree_balance_dirty(fs_info);
6692         return err;
6693 
6694 out_unlock_inode:
6695         unlock_new_inode(inode);
6696         goto out_unlock;
6697 
6698 }
6699 
6700 static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
6701                       struct dentry *dentry)
6702 {
6703         struct btrfs_trans_handle *trans = NULL;
6704         struct btrfs_root *root = BTRFS_I(dir)->root;
6705         struct inode *inode = d_inode(old_dentry);
6706         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
6707         u64 index;
6708         int err;
6709         int drop_inode = 0;
6710 
6711         /* do not allow sys_link's with other subvols of the same device */
6712         if (root->objectid != BTRFS_I(inode)->root->objectid)
6713                 return -EXDEV;
6714 
6715         if (inode->i_nlink >= BTRFS_LINK_MAX)
6716                 return -EMLINK;
6717 
6718         err = btrfs_set_inode_index(BTRFS_I(dir), &index);
6719         if (err)
6720                 goto fail;
6721 
6722         /*
6723          * 2 items for inode and inode ref
6724          * 2 items for dir items
6725          * 1 item for parent inode
6726          */
6727         trans = btrfs_start_transaction(root, 5);
6728         if (IS_ERR(trans)) {
6729                 err = PTR_ERR(trans);
6730                 trans = NULL;
6731                 goto fail;
6732         }
6733 
6734         /* There are several dir indexes for this inode, clear the cache. */
6735         BTRFS_I(inode)->dir_index = 0ULL;
6736         inc_nlink(inode);
6737         inode_inc_iversion(inode);
6738         inode->i_ctime = current_time(inode);
6739         ihold(inode);
6740         set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
6741 
6742         err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry, BTRFS_I(inode),
6743                         1, index);
6744 
6745         if (err) {
6746                 drop_inode = 1;
6747         } else {
6748                 struct dentry *parent = dentry->d_parent;
6749                 err = btrfs_update_inode(trans, root, inode);
6750                 if (err)
6751                         goto fail;
6752                 if (inode->i_nlink == 1) {
6753                         /*
6754                          * If new hard link count is 1, it's a file created
6755                          * with open(2) O_TMPFILE flag.
6756                          */
6757                         err = btrfs_orphan_del(trans, BTRFS_I(inode));
6758                         if (err)
6759                                 goto fail;
6760                 }
6761                 d_instantiate(dentry, inode);
6762                 btrfs_log_new_name(trans, BTRFS_I(inode), NULL, parent);
6763         }
6764 
6765         btrfs_balance_delayed_items(fs_info);
6766 fail:
6767         if (trans)
6768                 btrfs_end_transaction(trans);
6769         if (drop_inode) {
6770                 inode_dec_link_count(inode);
6771                 iput(inode);
6772         }
6773         btrfs_btree_balance_dirty(fs_info);
6774         return err;
6775 }
6776 
6777 static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
6778 {
6779         struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
6780         struct inode *inode = NULL;
6781         struct btrfs_trans_handle *trans;
6782         struct btrfs_root *root = BTRFS_I(dir)->root;
6783         int err = 0;
6784         int drop_on_err = 0;
6785         u64 objectid = 0;
6786         u64 index = 0;
6787 
6788         /*
6789          * 2 items for inode and ref
6790          * 2 items for dir items
6791          * 1 for xattr if selinux is on
6792          */
6793         trans = btrfs_start_transaction(root, 5);
6794         if (IS_ERR(trans))
6795                 return PTR_ERR(trans);
6796 
6797         err = btrfs_find_free_ino(root, &objectid);
6798         if (err)
6799                 goto out_fail;
6800 
6801         inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
6802                         dentry->d_name.len, btrfs_ino(BTRFS_I(dir)), objectid,
6803                         S_IFDIR | mode, &index);
6804         if (IS_ERR(inode)) {
6805                 err = PTR_ERR(inode);
6806                 goto out_fail;
6807         }
6808 
6809         drop_on_err = 1;
6810         /* these must be set before we unlock the inode */
6811         inode->i_op = &btrfs_dir_inode_operations;
6812         inode->i_fop = &btrfs_dir_file_operations;
6813 
6814         err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
6815         if (err)
6816                 goto out_fail_inode;
6817 
6818         btrfs_i_size_write(BTRFS_I(inode), 0);
6819         err = btrfs_update_inode(trans, root, inode);
6820         if (err)
6821                 goto out_fail_inode;
6822 
6823         err = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode),
6824                         dentry->d_name.name,
6825                         dentry->d_name.len, 0, index);
6826         if (err)
6827                 goto out_fail_inode;
6828 
6829         d_instantiate(dentry, inode);
6830         /*
6831          * mkdir is special.  We're unlocking after we call d_instantiate
6832          * to avoid a race with nfsd calling d_instantiate.
6833          */
6834         unlock_new_inode(inode);
6835         drop_on_err = 0;
6836 
6837 out_fail:
6838         btrfs_end_transaction(trans);
6839         if (drop_on_err) {
6840                 inode_dec_link_count(inode);
6841                 iput(inode);
6842         }
6843         btrfs_balance_delayed_items(fs_info);
6844         btrfs_btree_balance_dirty(fs_info);
6845         return err;
6846 
6847 out_fail_inode:
6848         unlock_new_inode(inode);
6849         goto out_fail;
6850 }
6851 
6852 /* Find next extent map of a given extent map, caller needs to ensure locks */
6853 static struct extent_map *next_extent_map(struct extent_map *em)
6854 {
6855         struct rb_node *next;
6856 
6857         next = rb_next(&em->rb_node);
6858         if (!next)
6859                 return NULL;
6860         return container_of(next, struct extent_map, rb_node);
6861 }
6862 
6863 static struct extent_map *prev_extent_map(struct extent_map *em)
6864 {
6865         struct rb_node *prev;
6866 
6867         prev = rb_prev(&em->rb_node);
6868         if (!prev)
6869                 return NULL;
6870         return container_of(prev, struct extent_map, rb_node);
6871 }
6872 
6873 /* helper for btfs_get_extent.  Given an existing extent in the tree,
6874  * the existing extent is the nearest extent to map_start,
6875  * and an extent that you want to insert, deal with overlap and insert
6876  * the best fitted new extent into the tree.
6877  */
6878 static int merge_extent_mapping(struct extent_map_tree *em_tree,
6879                                 struct extent_map *existing,
6880                                 struct extent_map *em,
6881                                 u64 map_start)
6882 {
6883         struct extent_map *prev;
6884         struct extent_map *next;
6885         u64 start;
6886         u64 end;
6887         u64 start_diff;
6888 
6889         BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
6890 
6891         if (existing->start > map_start) {
6892                 next = existing;
6893                 prev = prev_extent_map(next);
6894         } else {
6895                 prev = existing;
6896                 next = next_extent_map(prev);
6897         }
6898 
6899         start = prev ? extent_map_end(prev) : em->start;
6900         start = max_t(u64, start, em->start);
6901         end = next ? next->start : extent_map_end(em);
6902         end = min_t(u64, end, extent_map_end(em));
6903         start_diff = start - em->start;
6904         em->start = start;
6905         em->len = end - start;
6906         if (em->block_start < EXTENT_MAP_LAST_BYTE &&
6907             !test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
6908                 em->block_start += start_diff;
6909                 em->block_len -= start_diff;
6910         }
6911         return add_extent_mapping(em_tree, em, 0);
6912 }
6913 
6914 static noinline int uncompress_inline(struct btrfs_path *path,
6915                                       struct page *page,
6916                                       size_t pg_offset, u64 extent_offset,
6917                                       struct btrfs_file_extent_item *item)
6918 {
6919         int ret;
6920         struct extent_buffer *leaf = path->nodes[0];
6921         char *tmp;
6922         size_t max_size;
6923         unsigned long inline_size;
6924         unsigned long ptr;
6925         int compress_type;
6926 
6927         WARN_ON(pg_offset != 0);
6928         compress_type = btrfs_file_extent_compression(leaf, item);
6929         max_size = btrfs_file_extent_ram_bytes(leaf, item);
6930         inline_size = btrfs_file_extent_inline_item_len(leaf,
6931                                         btrfs_item_nr(path->slots[0]));
6932         tmp = kmalloc(inline_size, GFP_NOFS);
6933         if (!tmp)
6934                 return -ENOMEM;
6935         ptr = btrfs_file_extent_inline_start(item);
6936 
6937         read_extent_buffer(leaf, tmp, ptr, inline_size);
6938 
6939         max_size = min_t(unsigned long, PAGE_SIZE, max_size);
6940         ret = btrfs_decompress(compress_type, tmp, page,
6941                                extent_offset, inline_size, max_size);
6942 
6943         /*
6944          * decompression code contains a memset to fill in any space between the end
6945          * of the uncompressed data and the end of max_size in case the decompressed
6946          * data ends up shorter than ram_bytes.  That doesn't cover the hole between
6947          * the end of an inline extent and the beginning of the next block, so we
6948          * cover that region here.
6949          */
6950 
6951         if (max_size + pg_offset < PAGE_SIZE) {
6952                 char *map = kmap(page);
6953                 memset(map + pg_offset + max_size, 0, PAGE_SIZE - max_size - pg_offset);
6954                 kunmap(page);
6955         }
6956         kfree(tmp);
6957         return ret;
6958 }
6959 
6960 /*
6961  * a bit scary, this does extent mapping from logical file offset to the disk.
6962  * the ugly parts come from merging extents from the disk with the in-ram
6963  * representation.  This gets more complex because of the data=ordered code,
6964  * where the in-ram extents might be locked pending data=ordered completion.
6965  *
6966  * This also copies inline extents directly into the page.
6967  */
6968 struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
6969                 struct page *page,
6970             size_t pg_offset, u64 start, u64 len,
6971                 int create)
6972 {
6973         struct btrfs_fs_info *fs_info = btrfs_sb(inode->vfs_inode.i_sb);
6974         int ret;
6975         int err = 0;
6976         u64 extent_start = 0;
6977         u64 extent_end = 0;
6978         u64 objectid = btrfs_ino(inode);
6979         u32 found_type;
6980         struct btrfs_path *path = NULL;
6981         struct btrfs_root *root = inode->root;
6982         struct btrfs_file_extent_item *item;
6983         struct extent_buffer *leaf;
6984         struct btrfs_key found_key;
6985         struct extent_map *em = NULL;
6986         struct extent_map_tree *em_tree = &inode->extent_tree;
6987         struct extent_io_tree *io_tree = &inode->io_tree;
6988         struct btrfs_trans_handle *trans = NULL;
6989         const bool new_inline = !page || create;
6990 
6991 again:
6992         read_lock(&em_tree->lock);
6993         em = lookup_extent_mapping(em_tree, start, len);
6994         if (em)
6995                 em->bdev = fs_info->fs_devices->latest_bdev;
6996         read_unlock(&em_tree->lock);
6997 
6998         if (em) {
6999                 if (em->start > start || em->start + em->len <= start)
7000                         free_extent_map(em);
7001                 else if (em->block_start == EXTENT_MAP_INLINE && page)
7002                         free_extent_map(em);
7003                 else
7004                         goto out;
7005         }
7006         em = alloc_extent_map();
7007         if (!em) {
7008                 err = -ENOMEM;
7009                 goto out;
7010         }
7011         em->bdev = fs_info->fs_devices->latest_bdev;
7012         em->start = EXTENT_MAP_HOLE;
7013         em->orig_start = EXTENT_MAP_HOLE;
7014         em->len = (u64)-1;
7015         em->block_len = (u64)-1;
7016 
7017         if (!path) {
7018                 path = btrfs_alloc_path();
7019                 if (!path) {
7020                         err = -ENOMEM;
7021                         goto out;
7022                 }
7023                 /*
7024                  * Chances are we'll be called again, so go ahead and do
7025                  * readahead
7026                  */
7027                 path->reada = READA_FORWARD;
7028         }
7029 
7030         ret = btrfs_lookup_file_extent(trans, root, path,
7031                                        objectid, start, trans != NULL);
7032         if (ret < 0) {
7033                 err = ret;
7034                 goto out;
7035         }
7036 
7037         if (ret != 0) {
7038                 if (path->slots[0] == 0)
7039                         goto not_found;
7040                 path->slots[0]--;
7041         }
7042 
7043         leaf = path->nodes[0];
7044         item = btrfs_item_ptr(leaf, path->slots[0],
7045                               struct btrfs_file_extent_item);
7046         /* are we inside the extent that was found? */
7047         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
7048         found_type = found_key.type;
7049         if (found_key.objectid != objectid ||
7050             found_type != BTRFS_EXTENT_DATA_KEY) {
7051                 /*
7052                  * If we backup past the first extent we want to move forward
7053                  * and see if there is an extent in front of us, otherwise we'll
7054                  * say there is a hole for our whole search range which can
7055                  * cause problems.
7056                  */
7057                 extent_end = start;
7058                 goto next;
7059         }
7060 
7061         found_type = btrfs_file_extent_type(leaf, item);
7062         extent_start = found_key.offset;
7063         if (found_type == BTRFS_FILE_EXTENT_REG ||
7064             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
7065                 extent_end = extent_start +
7066                        btrfs_file_extent_num_bytes(leaf, item);
7067 
7068                 trace_btrfs_get_extent_show_fi_regular(inode, leaf, item,
7069                                                        extent_start);
7070         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
7071                 size_t size;
7072                 size = btrfs_file_extent_inline_len(leaf, path->slots[0], item);
7073                 extent_end = ALIGN(extent_start + size,
7074                                    fs_info->sectorsize);
7075 
7076                 trace_btrfs_get_extent_show_fi_inline(inode, leaf, item,
7077                                                       path->slots[0],
7078                                                       extent_start);
7079         }
7080 next:
7081         if (start >= extent_end) {
7082                 path->slots[0]++;
7083                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
7084                         ret = btrfs_next_leaf(root, path);
7085                         if (ret < 0) {
7086                                 err = ret;
7087                                 goto out;
7088                         }
7089                         if (ret > 0)
7090                                 goto not_found;
7091                         leaf = path->nodes[0];
7092                 }
7093                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
7094                 if (found_key.objectid != objectid ||
7095                     found_key.type != BTRFS_EXTENT_DATA_KEY)
7096                         goto not_found;
7097                 if (start + len <= found_key.offset)
7098                         goto not_found;
7099                 if (start > found_key.offset)
7100                         goto next;
7101                 em->start = start;
7102                 em->orig_start = start;
7103                 em->len = found_key.offset - start;
7104                 goto not_found_em;
7105         }
7106 
7107         btrfs_extent_item_to_extent_map(inode, path, item,
7108                         new_inline, em);
7109 
7110         if (found_type == BTRFS_FILE_EXTENT_REG ||
7111             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
7112                 goto insert;
7113         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
7114                 unsigned long ptr;
7115                 char *map;
7116                 size_t size;
7117                 size_t extent_offset;
7118                 size_t copy_size;
7119 
7120                 if (new_inline)
7121                         goto out;
7122 
7123                 size = btrfs_file_extent_inline_len(leaf, path->slots[0], item);
7124                 extent_offset = page_offset(page) + pg_offset - extent_start;
7125                 copy_size = min_t(u64, PAGE_SIZE - pg_offset,
7126                                   size - extent_offset);
7127                 em->start = extent_start + extent_offset;
7128                 em->len = ALIGN(copy_size, fs_info->sectorsize);
7129                 em->orig_block_len = em->len;
7130                 em->orig_start = em->start;
7131                 ptr = btrfs_file_extent_inline_start(item) + extent_offset;
7132                 if (create == 0 && !PageUptodate(page)) {
7133                         if (btrfs_file_extent_compression(leaf, item) !=
7134                             BTRFS_COMPRESS_NONE) {
7135                                 ret = uncompress_inline(path, page, pg_offset,
7136                                                         extent_offset, item);
7137                                 if (ret) {
7138                                         err = ret;
7139                                         goto out;
7140                                 }
7141                         } else {
7142                                 map = kmap(page);
7143                                 read_extent_buffer(leaf, map + pg_offset, ptr,
7144                                                    copy_size);
7145                                 if (pg_offset + copy_size < PAGE_SIZE) {
7146                                         memset(map + pg_offset + copy_size, 0,
7147                                                PAGE_SIZE - pg_offset -
7148                                                copy_size);
7149                                 }
7150                                 kunmap(page);
7151                         }
7152                         flush_dcache_page(page);
7153                 } else if (create && PageUptodate(page)) {
7154                         BUG();
7155                         if (!trans) {
7156                                 kunmap(page);
7157                                 free_extent_map(em);
7158                                 em = NULL;
7159 
7160                                 btrfs_release_path(path);
7161                                 trans = btrfs_join_transaction(root);
7162 
7163                                 if (IS_ERR(trans))
7164                                         return ERR_CAST(trans);
7165                                 goto again;
7166                         }
7167                         map = kmap(page);
7168                         write_extent_buffer(leaf, map + pg_offset, ptr,
7169                                             copy_size);
7170                         kunmap(page);
7171                         btrfs_mark_buffer_dirty(leaf);
7172                 }
7173                 set_extent_uptodate(io_tree, em->start,
7174                                     extent_map_end(em) - 1, NULL, GFP_NOFS);
7175                 goto insert;
7176         }
7177 not_found:
7178         em->start = start;
7179         em->orig_start = start;
7180         em->len = len;
7181 not_found_em:
7182         em->block_start = EXTENT_MAP_HOLE;
7183         set_bit(EXTENT_FLAG_VACANCY, &em->flags);
7184 insert:
7185         btrfs_release_path(path);
7186         if (em->start > start || extent_map_end(em) <= start) {
7187                 btrfs_err(fs_info,
7188                           "bad extent! em: [%llu %llu] passed [%llu %llu]",
7189                           em->start, em->len, start, len);
7190                 err = -EIO;
7191                 goto out;
7192         }
7193 
7194         err = 0;
7195         write_lock(&em_tree->lock);
7196         ret = add_extent_mapping(em_tree, em, 0);
7197         /* it is possible that someone inserted the extent into the tree
7198          * while we had the lock dropped.  It is also possible that
7199          * an overlapping map exists in the tree
7200          */
7201         if (ret == -EEXIST) {
7202                 struct extent_map *existing;
7203 
7204                 ret = 0;
7205 
7206                 existing = search_extent_mapping(em_tree, start, len);
7207                 /*
7208                  * existing will always be non-NULL, since there must be
7209                  * extent causing the -EEXIST.
7210                  */
7211                 if (existing->start == em->start &&
7212                     extent_map_end(existing) >= extent_map_end(em) &&
7213                     em->block_start == existing->block_start) {
7214                         /*
7215                          * The existing extent map already encompasses the
7216                          * entire extent map we tried to add.
7217                          */
7218                         free_extent_map(em);
7219                         em = existing;
7220                         err = 0;
7221 
7222                 } else if (start >= extent_map_end(existing) ||
7223                     start <= existing->start) {
7224                         /*
7225                          * The existing extent map is the one nearest to
7226                          * the [start, start + len) range which overlaps
7227                          */
7228                         err = merge_extent_mapping(em_tree, existing,
7229                                                    em, start);
7230                         free_extent_map(existing);
7231                         if (err) {
7232                                 free_extent_map(em);
7233                                 em = NULL;
7234                         }
7235                 } else {
7236                         free_extent_map(em);
7237                         em = existing;
7238                         err = 0;
7239                 }
7240         }
7241         write_unlock(&em_tree->lock);
7242 out:
7243 
7244         trace_btrfs_get_extent(root, inode, em);
7245 
7246         btrfs_free_path(path);
7247         if (trans) {
7248                 ret = btrfs_end_transaction(trans);
7249                 if (!err)
7250                         err = ret;
7251         }
7252         if (err) {
7253                 free_extent_map(em);
7254                 return ERR_PTR(err);
7255         }
7256         BUG_ON(!em); /* Error is always set */
7257         return em;
7258 }
7259 
7260 struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
7261                 struct page *page,
7262                 size_t pg_offset, u64 start, u64 len,
7263                 int create)
7264 {
7265         struct extent_map *em;
7266         struct extent_map *hole_em = NULL;
7267         u64 range_start = start;
7268         u64 end;
7269         u64 found;
7270         u64 found_end;
7271         int err = 0;
7272 
7273         em = btrfs_get_extent(inode, page, pg_offset, start, len, create);
7274         if (IS_ERR(em))
7275                 return em;
7276         /*
7277          * If our em maps to:
7278          * - a hole or
7279          * - a pre-alloc extent,
7280          * there might actually be delalloc bytes behind it.
7281          */
7282         if (em->block_start != EXTENT_MAP_HOLE &&
7283             !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
7284                 return em;
7285         else
7286                 hole_em = em;
7287 
7288         /* check to see if we've wrapped (len == -1 or similar) */
7289         end = start + len;
7290         if (end < start)
7291                 end = (u64)-1;
7292         else
7293                 end -= 1;
7294 
7295         em = NULL;
7296 
7297         /* ok, we didn't find anything, lets look for delalloc */
7298         found = count_range_bits(&inode->io_tree, &range_start,
7299                                  end, len, EXTENT_DELALLOC, 1);
7300         found_end = range_start + found;
7301         if (found_end < range_start)
7302                 found_end = (u64)-1;
7303 
7304         /*
7305          * we didn't find anything useful, return
7306          * the original results from get_extent()
7307          */
7308         if (range_start > end || found_end <= start) {
7309                 em = hole_em;
7310                 hole_em = NULL;
7311                 goto out;
7312         }
7313 
7314         /* adjust the range_start to make sure it doesn't
7315          * go backwards from the start they passed in
7316          */
7317         range_start = max(start, range_start);
7318         found = found_end - range_start;
7319 
7320         if (found > 0) {
7321                 u64 hole_start = start;
7322                 u64 hole_len = len;
7323 
7324                 em = alloc_extent_map();
7325                 if (!em) {
7326                         err = -ENOMEM;
7327                         goto out;
7328                 }
7329                 /*
7330                  * when btrfs_get_extent can't find anything it
7331                  * returns one huge hole
7332                  *
7333                  * make sure what it found really fits our range, and
7334                  * adjust to make sure it is based on the start from
7335                  * the caller
7336                  */
7337                 if (hole_em) {
7338                         u64 calc_end = extent_map_end(hole_em);
7339 
7340                         if (calc_end <= start || (hole_em->start > end)) {
7341                                 free_extent_map(hole_em);
7342                                 hole_em = NULL;
7343                         } else {
7344                                 hole_start = max(hole_em->start, start);
7345                                 hole_len = calc_end - hole_start;
7346                         }
7347                 }
7348                 em->bdev = NULL;
7349                 if (hole_em && range_start > hole_start) {
7350                         /* our hole starts before our delalloc, so we
7351                          * have to return just the parts of the hole
7352                          * that go until  the delalloc starts
7353                          */
7354                         em->len = min(hole_len,
7355                                       range_start - hole_start);
7356                         em->start = hole_start;
7357                         em->orig_start = hole_start;
7358                         /*
7359                          * don't adjust block start at all,
7360                          * it is fixed at EXTENT_MAP_HOLE
7361                          */
7362                         em->block_start = hole_em->block_start;
7363                         em->block_len = hole_len;
7364                         if (test_bit(EXTENT_FLAG_PREALLOC, &hole_em->flags))
7365                                 set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
7366                 } else {
7367                         em->start = range_start;
7368                         em->len = found;
7369                         em->orig_start = range_start;
7370                         em->block_start = EXTENT_MAP_DELALLOC;
7371                         em->block_len = found;
7372                 }
7373         } else if (hole_em) {
7374                 return hole_em;
7375         }
7376 out:
7377 
7378         free_extent_map(hole_em);
7379         if (err) {
7380                 free_extent_map(em);
7381                 return ERR_PTR(err);
7382         }
7383         return em;
7384 }
7385 
7386 static struct extent_map *btrfs_create_dio_extent(struct inode *inode,
7387                                                   const u64 start,
7388                                                   const u64 len,
7389                                                   const u64 orig_start,
7390                                                   const u64 block_start,
7391                                                   const u64 block_len,
7392                                                   const u64 orig_block_len,
7393                                                   const u64 ram_bytes,
7394                                                   const int type)
7395 {
7396         struct extent_map *em = NULL;
7397         int ret;
7398 
7399         if (type != BTRFS_ORDERED_NOCOW) {
7400                 em = create_io_em(inode, start, len, orig_start,
7401                                   block_start, block_len, orig_block_len,
7402                                   ram_bytes,
7403                                   BTRFS_COMPRESS_NONE, /* compress_type */
7404                                   type);
7405                 if (IS_ERR(em))
7406                         goto out;
7407         }
7408         ret = btrfs_add_ordered_extent_dio(inode, start, block_start,
7409                                            len, block_len, type);
7410         if (ret) {
7411                 if (em) {
7412                         free_extent_map(em);
7413                         btrfs_drop_extent_cache(BTRFS_I(inode), start,
7414                                                 start + len - 1, 0);
7415                 }
7416                 em = ERR_PTR(ret);
7417         }
7418  out:
7419 
7420         return em;
7421 }
7422 
7423 static struct extent_map *btrfs_new_extent_direct(struct inode *inode,
7424                                                   u64 start, u64 len)
7425 {
7426         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
7427         struct btrfs_root *root = BTRFS_I(inode)->root;
7428         struct extent_map *em;
7429         struct btrfs_key ins;
7430         u64 alloc_hint;
7431         int ret;
7432 
7433         alloc_hint = get_extent_allocation_hint(inode, start, len);
7434         ret = btrfs_reserve_extent(root, len, len, fs_info->sectorsize,
7435                                    0, alloc_hint, &ins, 1, 1);
7436         if (ret)
7437                 return ERR_PTR(ret);
7438 
7439         em = btrfs_create_dio_extent(inode, start, ins.offset, start,
7440                                      ins.objectid, ins.offset, ins.offset,
7441                                      ins.offset, BTRFS_ORDERED_REGULAR);
7442         btrfs_dec_block_group_reservations(fs_info, ins.objectid);
7443         if (IS_ERR(em))
7444                 btrfs_free_reserved_extent(fs_info, ins.objectid,
7445                                            ins.offset, 1);
7446 
7447         return em;
7448 }
7449 
7450 /*
7451  * returns 1 when the nocow is safe, < 1 on error, 0 if the
7452  * block must be cow'd
7453  */
7454 noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
7455                               u64 *orig_start, u64 *orig_block_len,
7456                               u64 *ram_bytes)
7457 {
7458         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
7459         struct btrfs_path *path;
7460         int ret;
7461         struct extent_buffer *leaf;
7462         struct btrfs_root *root = BTRFS_I(inode)->root;
7463         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
7464         struct btrfs_file_extent_item *fi;
7465         struct btrfs_key key;