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

Version: ~ [ linux-5.4-rc7 ] ~ [ linux-5.3.10 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.83 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.153 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.200 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.200 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.76 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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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/fs.h>
 20 #include <linux/pagemap.h>
 21 #include <linux/highmem.h>
 22 #include <linux/time.h>
 23 #include <linux/init.h>
 24 #include <linux/string.h>
 25 #include <linux/backing-dev.h>
 26 #include <linux/mpage.h>
 27 #include <linux/falloc.h>
 28 #include <linux/swap.h>
 29 #include <linux/writeback.h>
 30 #include <linux/statfs.h>
 31 #include <linux/compat.h>
 32 #include <linux/slab.h>
 33 #include <linux/btrfs.h>
 34 #include <linux/uio.h>
 35 #include "ctree.h"
 36 #include "disk-io.h"
 37 #include "transaction.h"
 38 #include "btrfs_inode.h"
 39 #include "print-tree.h"
 40 #include "tree-log.h"
 41 #include "locking.h"
 42 #include "volumes.h"
 43 #include "qgroup.h"
 44 #include "compression.h"
 45 
 46 static struct kmem_cache *btrfs_inode_defrag_cachep;
 47 /*
 48  * when auto defrag is enabled we
 49  * queue up these defrag structs to remember which
 50  * inodes need defragging passes
 51  */
 52 struct inode_defrag {
 53         struct rb_node rb_node;
 54         /* objectid */
 55         u64 ino;
 56         /*
 57          * transid where the defrag was added, we search for
 58          * extents newer than this
 59          */
 60         u64 transid;
 61 
 62         /* root objectid */
 63         u64 root;
 64 
 65         /* last offset we were able to defrag */
 66         u64 last_offset;
 67 
 68         /* if we've wrapped around back to zero once already */
 69         int cycled;
 70 };
 71 
 72 static int __compare_inode_defrag(struct inode_defrag *defrag1,
 73                                   struct inode_defrag *defrag2)
 74 {
 75         if (defrag1->root > defrag2->root)
 76                 return 1;
 77         else if (defrag1->root < defrag2->root)
 78                 return -1;
 79         else if (defrag1->ino > defrag2->ino)
 80                 return 1;
 81         else if (defrag1->ino < defrag2->ino)
 82                 return -1;
 83         else
 84                 return 0;
 85 }
 86 
 87 /* pop a record for an inode into the defrag tree.  The lock
 88  * must be held already
 89  *
 90  * If you're inserting a record for an older transid than an
 91  * existing record, the transid already in the tree is lowered
 92  *
 93  * If an existing record is found the defrag item you
 94  * pass in is freed
 95  */
 96 static int __btrfs_add_inode_defrag(struct inode *inode,
 97                                     struct inode_defrag *defrag)
 98 {
 99         struct btrfs_root *root = BTRFS_I(inode)->root;
100         struct inode_defrag *entry;
101         struct rb_node **p;
102         struct rb_node *parent = NULL;
103         int ret;
104 
105         p = &root->fs_info->defrag_inodes.rb_node;
106         while (*p) {
107                 parent = *p;
108                 entry = rb_entry(parent, struct inode_defrag, rb_node);
109 
110                 ret = __compare_inode_defrag(defrag, entry);
111                 if (ret < 0)
112                         p = &parent->rb_left;
113                 else if (ret > 0)
114                         p = &parent->rb_right;
115                 else {
116                         /* if we're reinserting an entry for
117                          * an old defrag run, make sure to
118                          * lower the transid of our existing record
119                          */
120                         if (defrag->transid < entry->transid)
121                                 entry->transid = defrag->transid;
122                         if (defrag->last_offset > entry->last_offset)
123                                 entry->last_offset = defrag->last_offset;
124                         return -EEXIST;
125                 }
126         }
127         set_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
128         rb_link_node(&defrag->rb_node, parent, p);
129         rb_insert_color(&defrag->rb_node, &root->fs_info->defrag_inodes);
130         return 0;
131 }
132 
133 static inline int __need_auto_defrag(struct btrfs_root *root)
134 {
135         if (!btrfs_test_opt(root, AUTO_DEFRAG))
136                 return 0;
137 
138         if (btrfs_fs_closing(root->fs_info))
139                 return 0;
140 
141         return 1;
142 }
143 
144 /*
145  * insert a defrag record for this inode if auto defrag is
146  * enabled
147  */
148 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
149                            struct inode *inode)
150 {
151         struct btrfs_root *root = BTRFS_I(inode)->root;
152         struct inode_defrag *defrag;
153         u64 transid;
154         int ret;
155 
156         if (!__need_auto_defrag(root))
157                 return 0;
158 
159         if (test_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags))
160                 return 0;
161 
162         if (trans)
163                 transid = trans->transid;
164         else
165                 transid = BTRFS_I(inode)->root->last_trans;
166 
167         defrag = kmem_cache_zalloc(btrfs_inode_defrag_cachep, GFP_NOFS);
168         if (!defrag)
169                 return -ENOMEM;
170 
171         defrag->ino = btrfs_ino(inode);
172         defrag->transid = transid;
173         defrag->root = root->root_key.objectid;
174 
175         spin_lock(&root->fs_info->defrag_inodes_lock);
176         if (!test_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags)) {
177                 /*
178                  * If we set IN_DEFRAG flag and evict the inode from memory,
179                  * and then re-read this inode, this new inode doesn't have
180                  * IN_DEFRAG flag. At the case, we may find the existed defrag.
181                  */
182                 ret = __btrfs_add_inode_defrag(inode, defrag);
183                 if (ret)
184                         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
185         } else {
186                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
187         }
188         spin_unlock(&root->fs_info->defrag_inodes_lock);
189         return 0;
190 }
191 
192 /*
193  * Requeue the defrag object. If there is a defrag object that points to
194  * the same inode in the tree, we will merge them together (by
195  * __btrfs_add_inode_defrag()) and free the one that we want to requeue.
196  */
197 static void btrfs_requeue_inode_defrag(struct inode *inode,
198                                        struct inode_defrag *defrag)
199 {
200         struct btrfs_root *root = BTRFS_I(inode)->root;
201         int ret;
202 
203         if (!__need_auto_defrag(root))
204                 goto out;
205 
206         /*
207          * Here we don't check the IN_DEFRAG flag, because we need merge
208          * them together.
209          */
210         spin_lock(&root->fs_info->defrag_inodes_lock);
211         ret = __btrfs_add_inode_defrag(inode, defrag);
212         spin_unlock(&root->fs_info->defrag_inodes_lock);
213         if (ret)
214                 goto out;
215         return;
216 out:
217         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
218 }
219 
220 /*
221  * pick the defragable inode that we want, if it doesn't exist, we will get
222  * the next one.
223  */
224 static struct inode_defrag *
225 btrfs_pick_defrag_inode(struct btrfs_fs_info *fs_info, u64 root, u64 ino)
226 {
227         struct inode_defrag *entry = NULL;
228         struct inode_defrag tmp;
229         struct rb_node *p;
230         struct rb_node *parent = NULL;
231         int ret;
232 
233         tmp.ino = ino;
234         tmp.root = root;
235 
236         spin_lock(&fs_info->defrag_inodes_lock);
237         p = fs_info->defrag_inodes.rb_node;
238         while (p) {
239                 parent = p;
240                 entry = rb_entry(parent, struct inode_defrag, rb_node);
241 
242                 ret = __compare_inode_defrag(&tmp, entry);
243                 if (ret < 0)
244                         p = parent->rb_left;
245                 else if (ret > 0)
246                         p = parent->rb_right;
247                 else
248                         goto out;
249         }
250 
251         if (parent && __compare_inode_defrag(&tmp, entry) > 0) {
252                 parent = rb_next(parent);
253                 if (parent)
254                         entry = rb_entry(parent, struct inode_defrag, rb_node);
255                 else
256                         entry = NULL;
257         }
258 out:
259         if (entry)
260                 rb_erase(parent, &fs_info->defrag_inodes);
261         spin_unlock(&fs_info->defrag_inodes_lock);
262         return entry;
263 }
264 
265 void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info)
266 {
267         struct inode_defrag *defrag;
268         struct rb_node *node;
269 
270         spin_lock(&fs_info->defrag_inodes_lock);
271         node = rb_first(&fs_info->defrag_inodes);
272         while (node) {
273                 rb_erase(node, &fs_info->defrag_inodes);
274                 defrag = rb_entry(node, struct inode_defrag, rb_node);
275                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
276 
277                 cond_resched_lock(&fs_info->defrag_inodes_lock);
278 
279                 node = rb_first(&fs_info->defrag_inodes);
280         }
281         spin_unlock(&fs_info->defrag_inodes_lock);
282 }
283 
284 #define BTRFS_DEFRAG_BATCH      1024
285 
286 static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
287                                     struct inode_defrag *defrag)
288 {
289         struct btrfs_root *inode_root;
290         struct inode *inode;
291         struct btrfs_key key;
292         struct btrfs_ioctl_defrag_range_args range;
293         int num_defrag;
294         int index;
295         int ret;
296 
297         /* get the inode */
298         key.objectid = defrag->root;
299         key.type = BTRFS_ROOT_ITEM_KEY;
300         key.offset = (u64)-1;
301 
302         index = srcu_read_lock(&fs_info->subvol_srcu);
303 
304         inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
305         if (IS_ERR(inode_root)) {
306                 ret = PTR_ERR(inode_root);
307                 goto cleanup;
308         }
309 
310         key.objectid = defrag->ino;
311         key.type = BTRFS_INODE_ITEM_KEY;
312         key.offset = 0;
313         inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
314         if (IS_ERR(inode)) {
315                 ret = PTR_ERR(inode);
316                 goto cleanup;
317         }
318         srcu_read_unlock(&fs_info->subvol_srcu, index);
319 
320         /* do a chunk of defrag */
321         clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
322         memset(&range, 0, sizeof(range));
323         range.len = (u64)-1;
324         range.start = defrag->last_offset;
325 
326         sb_start_write(fs_info->sb);
327         num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
328                                        BTRFS_DEFRAG_BATCH);
329         sb_end_write(fs_info->sb);
330         /*
331          * if we filled the whole defrag batch, there
332          * must be more work to do.  Queue this defrag
333          * again
334          */
335         if (num_defrag == BTRFS_DEFRAG_BATCH) {
336                 defrag->last_offset = range.start;
337                 btrfs_requeue_inode_defrag(inode, defrag);
338         } else if (defrag->last_offset && !defrag->cycled) {
339                 /*
340                  * we didn't fill our defrag batch, but
341                  * we didn't start at zero.  Make sure we loop
342                  * around to the start of the file.
343                  */
344                 defrag->last_offset = 0;
345                 defrag->cycled = 1;
346                 btrfs_requeue_inode_defrag(inode, defrag);
347         } else {
348                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
349         }
350 
351         iput(inode);
352         return 0;
353 cleanup:
354         srcu_read_unlock(&fs_info->subvol_srcu, index);
355         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
356         return ret;
357 }
358 
359 /*
360  * run through the list of inodes in the FS that need
361  * defragging
362  */
363 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
364 {
365         struct inode_defrag *defrag;
366         u64 first_ino = 0;
367         u64 root_objectid = 0;
368 
369         atomic_inc(&fs_info->defrag_running);
370         while (1) {
371                 /* Pause the auto defragger. */
372                 if (test_bit(BTRFS_FS_STATE_REMOUNTING,
373                              &fs_info->fs_state))
374                         break;
375 
376                 if (!__need_auto_defrag(fs_info->tree_root))
377                         break;
378 
379                 /* find an inode to defrag */
380                 defrag = btrfs_pick_defrag_inode(fs_info, root_objectid,
381                                                  first_ino);
382                 if (!defrag) {
383                         if (root_objectid || first_ino) {
384                                 root_objectid = 0;
385                                 first_ino = 0;
386                                 continue;
387                         } else {
388                                 break;
389                         }
390                 }
391 
392                 first_ino = defrag->ino + 1;
393                 root_objectid = defrag->root;
394 
395                 __btrfs_run_defrag_inode(fs_info, defrag);
396         }
397         atomic_dec(&fs_info->defrag_running);
398 
399         /*
400          * during unmount, we use the transaction_wait queue to
401          * wait for the defragger to stop
402          */
403         wake_up(&fs_info->transaction_wait);
404         return 0;
405 }
406 
407 /* simple helper to fault in pages and copy.  This should go away
408  * and be replaced with calls into generic code.
409  */
410 static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes,
411                                          struct page **prepared_pages,
412                                          struct iov_iter *i)
413 {
414         size_t copied = 0;
415         size_t total_copied = 0;
416         int pg = 0;
417         int offset = pos & (PAGE_SIZE - 1);
418 
419         while (write_bytes > 0) {
420                 size_t count = min_t(size_t,
421                                      PAGE_SIZE - offset, write_bytes);
422                 struct page *page = prepared_pages[pg];
423                 /*
424                  * Copy data from userspace to the current page
425                  */
426                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
427 
428                 /* Flush processor's dcache for this page */
429                 flush_dcache_page(page);
430 
431                 /*
432                  * if we get a partial write, we can end up with
433                  * partially up to date pages.  These add
434                  * a lot of complexity, so make sure they don't
435                  * happen by forcing this copy to be retried.
436                  *
437                  * The rest of the btrfs_file_write code will fall
438                  * back to page at a time copies after we return 0.
439                  */
440                 if (!PageUptodate(page) && copied < count)
441                         copied = 0;
442 
443                 iov_iter_advance(i, copied);
444                 write_bytes -= copied;
445                 total_copied += copied;
446 
447                 /* Return to btrfs_file_write_iter to fault page */
448                 if (unlikely(copied == 0))
449                         break;
450 
451                 if (copied < PAGE_SIZE - offset) {
452                         offset += copied;
453                 } else {
454                         pg++;
455                         offset = 0;
456                 }
457         }
458         return total_copied;
459 }
460 
461 /*
462  * unlocks pages after btrfs_file_write is done with them
463  */
464 static void btrfs_drop_pages(struct page **pages, size_t num_pages)
465 {
466         size_t i;
467         for (i = 0; i < num_pages; i++) {
468                 /* page checked is some magic around finding pages that
469                  * have been modified without going through btrfs_set_page_dirty
470                  * clear it here. There should be no need to mark the pages
471                  * accessed as prepare_pages should have marked them accessed
472                  * in prepare_pages via find_or_create_page()
473                  */
474                 ClearPageChecked(pages[i]);
475                 unlock_page(pages[i]);
476                 put_page(pages[i]);
477         }
478 }
479 
480 /*
481  * after copy_from_user, pages need to be dirtied and we need to make
482  * sure holes are created between the current EOF and the start of
483  * any next extents (if required).
484  *
485  * this also makes the decision about creating an inline extent vs
486  * doing real data extents, marking pages dirty and delalloc as required.
487  */
488 int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
489                              struct page **pages, size_t num_pages,
490                              loff_t pos, size_t write_bytes,
491                              struct extent_state **cached)
492 {
493         int err = 0;
494         int i;
495         u64 num_bytes;
496         u64 start_pos;
497         u64 end_of_last_block;
498         u64 end_pos = pos + write_bytes;
499         loff_t isize = i_size_read(inode);
500 
501         start_pos = pos & ~((u64)root->sectorsize - 1);
502         num_bytes = round_up(write_bytes + pos - start_pos, root->sectorsize);
503 
504         end_of_last_block = start_pos + num_bytes - 1;
505         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
506                                         cached);
507         if (err)
508                 return err;
509 
510         for (i = 0; i < num_pages; i++) {
511                 struct page *p = pages[i];
512                 SetPageUptodate(p);
513                 ClearPageChecked(p);
514                 set_page_dirty(p);
515         }
516 
517         /*
518          * we've only changed i_size in ram, and we haven't updated
519          * the disk i_size.  There is no need to log the inode
520          * at this time.
521          */
522         if (end_pos > isize)
523                 i_size_write(inode, end_pos);
524         return 0;
525 }
526 
527 /*
528  * this drops all the extents in the cache that intersect the range
529  * [start, end].  Existing extents are split as required.
530  */
531 void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
532                              int skip_pinned)
533 {
534         struct extent_map *em;
535         struct extent_map *split = NULL;
536         struct extent_map *split2 = NULL;
537         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
538         u64 len = end - start + 1;
539         u64 gen;
540         int ret;
541         int testend = 1;
542         unsigned long flags;
543         int compressed = 0;
544         bool modified;
545 
546         WARN_ON(end < start);
547         if (end == (u64)-1) {
548                 len = (u64)-1;
549                 testend = 0;
550         }
551         while (1) {
552                 int no_splits = 0;
553 
554                 modified = false;
555                 if (!split)
556                         split = alloc_extent_map();
557                 if (!split2)
558                         split2 = alloc_extent_map();
559                 if (!split || !split2)
560                         no_splits = 1;
561 
562                 write_lock(&em_tree->lock);
563                 em = lookup_extent_mapping(em_tree, start, len);
564                 if (!em) {
565                         write_unlock(&em_tree->lock);
566                         break;
567                 }
568                 flags = em->flags;
569                 gen = em->generation;
570                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
571                         if (testend && em->start + em->len >= start + len) {
572                                 free_extent_map(em);
573                                 write_unlock(&em_tree->lock);
574                                 break;
575                         }
576                         start = em->start + em->len;
577                         if (testend)
578                                 len = start + len - (em->start + em->len);
579                         free_extent_map(em);
580                         write_unlock(&em_tree->lock);
581                         continue;
582                 }
583                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
584                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
585                 clear_bit(EXTENT_FLAG_LOGGING, &flags);
586                 modified = !list_empty(&em->list);
587                 if (no_splits)
588                         goto next;
589 
590                 if (em->start < start) {
591                         split->start = em->start;
592                         split->len = start - em->start;
593 
594                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
595                                 split->orig_start = em->orig_start;
596                                 split->block_start = em->block_start;
597 
598                                 if (compressed)
599                                         split->block_len = em->block_len;
600                                 else
601                                         split->block_len = split->len;
602                                 split->orig_block_len = max(split->block_len,
603                                                 em->orig_block_len);
604                                 split->ram_bytes = em->ram_bytes;
605                         } else {
606                                 split->orig_start = split->start;
607                                 split->block_len = 0;
608                                 split->block_start = em->block_start;
609                                 split->orig_block_len = 0;
610                                 split->ram_bytes = split->len;
611                         }
612 
613                         split->generation = gen;
614                         split->bdev = em->bdev;
615                         split->flags = flags;
616                         split->compress_type = em->compress_type;
617                         replace_extent_mapping(em_tree, em, split, modified);
618                         free_extent_map(split);
619                         split = split2;
620                         split2 = NULL;
621                 }
622                 if (testend && em->start + em->len > start + len) {
623                         u64 diff = start + len - em->start;
624 
625                         split->start = start + len;
626                         split->len = em->start + em->len - (start + len);
627                         split->bdev = em->bdev;
628                         split->flags = flags;
629                         split->compress_type = em->compress_type;
630                         split->generation = gen;
631 
632                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
633                                 split->orig_block_len = max(em->block_len,
634                                                     em->orig_block_len);
635 
636                                 split->ram_bytes = em->ram_bytes;
637                                 if (compressed) {
638                                         split->block_len = em->block_len;
639                                         split->block_start = em->block_start;
640                                         split->orig_start = em->orig_start;
641                                 } else {
642                                         split->block_len = split->len;
643                                         split->block_start = em->block_start
644                                                 + diff;
645                                         split->orig_start = em->orig_start;
646                                 }
647                         } else {
648                                 split->ram_bytes = split->len;
649                                 split->orig_start = split->start;
650                                 split->block_len = 0;
651                                 split->block_start = em->block_start;
652                                 split->orig_block_len = 0;
653                         }
654 
655                         if (extent_map_in_tree(em)) {
656                                 replace_extent_mapping(em_tree, em, split,
657                                                        modified);
658                         } else {
659                                 ret = add_extent_mapping(em_tree, split,
660                                                          modified);
661                                 ASSERT(ret == 0); /* Logic error */
662                         }
663                         free_extent_map(split);
664                         split = NULL;
665                 }
666 next:
667                 if (extent_map_in_tree(em))
668                         remove_extent_mapping(em_tree, em);
669                 write_unlock(&em_tree->lock);
670 
671                 /* once for us */
672                 free_extent_map(em);
673                 /* once for the tree*/
674                 free_extent_map(em);
675         }
676         if (split)
677                 free_extent_map(split);
678         if (split2)
679                 free_extent_map(split2);
680 }
681 
682 /*
683  * this is very complex, but the basic idea is to drop all extents
684  * in the range start - end.  hint_block is filled in with a block number
685  * that would be a good hint to the block allocator for this file.
686  *
687  * If an extent intersects the range but is not entirely inside the range
688  * it is either truncated or split.  Anything entirely inside the range
689  * is deleted from the tree.
690  */
691 int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
692                          struct btrfs_root *root, struct inode *inode,
693                          struct btrfs_path *path, u64 start, u64 end,
694                          u64 *drop_end, int drop_cache,
695                          int replace_extent,
696                          u32 extent_item_size,
697                          int *key_inserted)
698 {
699         struct extent_buffer *leaf;
700         struct btrfs_file_extent_item *fi;
701         struct btrfs_key key;
702         struct btrfs_key new_key;
703         u64 ino = btrfs_ino(inode);
704         u64 search_start = start;
705         u64 disk_bytenr = 0;
706         u64 num_bytes = 0;
707         u64 extent_offset = 0;
708         u64 extent_end = 0;
709         int del_nr = 0;
710         int del_slot = 0;
711         int extent_type;
712         int recow;
713         int ret;
714         int modify_tree = -1;
715         int update_refs;
716         int found = 0;
717         int leafs_visited = 0;
718 
719         if (drop_cache)
720                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
721 
722         if (start >= BTRFS_I(inode)->disk_i_size && !replace_extent)
723                 modify_tree = 0;
724 
725         update_refs = (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
726                        root == root->fs_info->tree_root);
727         while (1) {
728                 recow = 0;
729                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
730                                                search_start, modify_tree);
731                 if (ret < 0)
732                         break;
733                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
734                         leaf = path->nodes[0];
735                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
736                         if (key.objectid == ino &&
737                             key.type == BTRFS_EXTENT_DATA_KEY)
738                                 path->slots[0]--;
739                 }
740                 ret = 0;
741                 leafs_visited++;
742 next_slot:
743                 leaf = path->nodes[0];
744                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
745                         BUG_ON(del_nr > 0);
746                         ret = btrfs_next_leaf(root, path);
747                         if (ret < 0)
748                                 break;
749                         if (ret > 0) {
750                                 ret = 0;
751                                 break;
752                         }
753                         leafs_visited++;
754                         leaf = path->nodes[0];
755                         recow = 1;
756                 }
757 
758                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
759 
760                 if (key.objectid > ino)
761                         break;
762                 if (WARN_ON_ONCE(key.objectid < ino) ||
763                     key.type < BTRFS_EXTENT_DATA_KEY) {
764                         ASSERT(del_nr == 0);
765                         path->slots[0]++;
766                         goto next_slot;
767                 }
768                 if (key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
769                         break;
770 
771                 fi = btrfs_item_ptr(leaf, path->slots[0],
772                                     struct btrfs_file_extent_item);
773                 extent_type = btrfs_file_extent_type(leaf, fi);
774 
775                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
776                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
777                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
778                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
779                         extent_offset = btrfs_file_extent_offset(leaf, fi);
780                         extent_end = key.offset +
781                                 btrfs_file_extent_num_bytes(leaf, fi);
782                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
783                         extent_end = key.offset +
784                                 btrfs_file_extent_inline_len(leaf,
785                                                      path->slots[0], fi);
786                 } else {
787                         /* can't happen */
788                         BUG();
789                 }
790 
791                 /*
792                  * Don't skip extent items representing 0 byte lengths. They
793                  * used to be created (bug) if while punching holes we hit
794                  * -ENOSPC condition. So if we find one here, just ensure we
795                  * delete it, otherwise we would insert a new file extent item
796                  * with the same key (offset) as that 0 bytes length file
797                  * extent item in the call to setup_items_for_insert() later
798                  * in this function.
799                  */
800                 if (extent_end == key.offset && extent_end >= search_start)
801                         goto delete_extent_item;
802 
803                 if (extent_end <= search_start) {
804                         path->slots[0]++;
805                         goto next_slot;
806                 }
807 
808                 found = 1;
809                 search_start = max(key.offset, start);
810                 if (recow || !modify_tree) {
811                         modify_tree = -1;
812                         btrfs_release_path(path);
813                         continue;
814                 }
815 
816                 /*
817                  *     | - range to drop - |
818                  *  | -------- extent -------- |
819                  */
820                 if (start > key.offset && end < extent_end) {
821                         BUG_ON(del_nr > 0);
822                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
823                                 ret = -EOPNOTSUPP;
824                                 break;
825                         }
826 
827                         memcpy(&new_key, &key, sizeof(new_key));
828                         new_key.offset = start;
829                         ret = btrfs_duplicate_item(trans, root, path,
830                                                    &new_key);
831                         if (ret == -EAGAIN) {
832                                 btrfs_release_path(path);
833                                 continue;
834                         }
835                         if (ret < 0)
836                                 break;
837 
838                         leaf = path->nodes[0];
839                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
840                                             struct btrfs_file_extent_item);
841                         btrfs_set_file_extent_num_bytes(leaf, fi,
842                                                         start - key.offset);
843 
844                         fi = btrfs_item_ptr(leaf, path->slots[0],
845                                             struct btrfs_file_extent_item);
846 
847                         extent_offset += start - key.offset;
848                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
849                         btrfs_set_file_extent_num_bytes(leaf, fi,
850                                                         extent_end - start);
851                         btrfs_mark_buffer_dirty(leaf);
852 
853                         if (update_refs && disk_bytenr > 0) {
854                                 ret = btrfs_inc_extent_ref(trans, root,
855                                                 disk_bytenr, num_bytes, 0,
856                                                 root->root_key.objectid,
857                                                 new_key.objectid,
858                                                 start - extent_offset);
859                                 BUG_ON(ret); /* -ENOMEM */
860                         }
861                         key.offset = start;
862                 }
863                 /*
864                  *  | ---- range to drop ----- |
865                  *      | -------- extent -------- |
866                  */
867                 if (start <= key.offset && end < extent_end) {
868                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
869                                 ret = -EOPNOTSUPP;
870                                 break;
871                         }
872 
873                         memcpy(&new_key, &key, sizeof(new_key));
874                         new_key.offset = end;
875                         btrfs_set_item_key_safe(root->fs_info, path, &new_key);
876 
877                         extent_offset += end - key.offset;
878                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
879                         btrfs_set_file_extent_num_bytes(leaf, fi,
880                                                         extent_end - end);
881                         btrfs_mark_buffer_dirty(leaf);
882                         if (update_refs && disk_bytenr > 0)
883                                 inode_sub_bytes(inode, end - key.offset);
884                         break;
885                 }
886 
887                 search_start = extent_end;
888                 /*
889                  *       | ---- range to drop ----- |
890                  *  | -------- extent -------- |
891                  */
892                 if (start > key.offset && end >= extent_end) {
893                         BUG_ON(del_nr > 0);
894                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
895                                 ret = -EOPNOTSUPP;
896                                 break;
897                         }
898 
899                         btrfs_set_file_extent_num_bytes(leaf, fi,
900                                                         start - key.offset);
901                         btrfs_mark_buffer_dirty(leaf);
902                         if (update_refs && disk_bytenr > 0)
903                                 inode_sub_bytes(inode, extent_end - start);
904                         if (end == extent_end)
905                                 break;
906 
907                         path->slots[0]++;
908                         goto next_slot;
909                 }
910 
911                 /*
912                  *  | ---- range to drop ----- |
913                  *    | ------ extent ------ |
914                  */
915                 if (start <= key.offset && end >= extent_end) {
916 delete_extent_item:
917                         if (del_nr == 0) {
918                                 del_slot = path->slots[0];
919                                 del_nr = 1;
920                         } else {
921                                 BUG_ON(del_slot + del_nr != path->slots[0]);
922                                 del_nr++;
923                         }
924 
925                         if (update_refs &&
926                             extent_type == BTRFS_FILE_EXTENT_INLINE) {
927                                 inode_sub_bytes(inode,
928                                                 extent_end - key.offset);
929                                 extent_end = ALIGN(extent_end,
930                                                    root->sectorsize);
931                         } else if (update_refs && disk_bytenr > 0) {
932                                 ret = btrfs_free_extent(trans, root,
933                                                 disk_bytenr, num_bytes, 0,
934                                                 root->root_key.objectid,
935                                                 key.objectid, key.offset -
936                                                 extent_offset);
937                                 BUG_ON(ret); /* -ENOMEM */
938                                 inode_sub_bytes(inode,
939                                                 extent_end - key.offset);
940                         }
941 
942                         if (end == extent_end)
943                                 break;
944 
945                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
946                                 path->slots[0]++;
947                                 goto next_slot;
948                         }
949 
950                         ret = btrfs_del_items(trans, root, path, del_slot,
951                                               del_nr);
952                         if (ret) {
953                                 btrfs_abort_transaction(trans, root, ret);
954                                 break;
955                         }
956 
957                         del_nr = 0;
958                         del_slot = 0;
959 
960                         btrfs_release_path(path);
961                         continue;
962                 }
963 
964                 BUG_ON(1);
965         }
966 
967         if (!ret && del_nr > 0) {
968                 /*
969                  * Set path->slots[0] to first slot, so that after the delete
970                  * if items are move off from our leaf to its immediate left or
971                  * right neighbor leafs, we end up with a correct and adjusted
972                  * path->slots[0] for our insertion (if replace_extent != 0).
973                  */
974                 path->slots[0] = del_slot;
975                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
976                 if (ret)
977                         btrfs_abort_transaction(trans, root, ret);
978         }
979 
980         leaf = path->nodes[0];
981         /*
982          * If btrfs_del_items() was called, it might have deleted a leaf, in
983          * which case it unlocked our path, so check path->locks[0] matches a
984          * write lock.
985          */
986         if (!ret && replace_extent && leafs_visited == 1 &&
987             (path->locks[0] == BTRFS_WRITE_LOCK_BLOCKING ||
988              path->locks[0] == BTRFS_WRITE_LOCK) &&
989             btrfs_leaf_free_space(root, leaf) >=
990             sizeof(struct btrfs_item) + extent_item_size) {
991 
992                 key.objectid = ino;
993                 key.type = BTRFS_EXTENT_DATA_KEY;
994                 key.offset = start;
995                 if (!del_nr && path->slots[0] < btrfs_header_nritems(leaf)) {
996                         struct btrfs_key slot_key;
997 
998                         btrfs_item_key_to_cpu(leaf, &slot_key, path->slots[0]);
999                         if (btrfs_comp_cpu_keys(&key, &slot_key) > 0)
1000                                 path->slots[0]++;
1001                 }
1002                 setup_items_for_insert(root, path, &key,
1003                                        &extent_item_size,
1004                                        extent_item_size,
1005                                        sizeof(struct btrfs_item) +
1006                                        extent_item_size, 1);
1007                 *key_inserted = 1;
1008         }
1009 
1010         if (!replace_extent || !(*key_inserted))
1011                 btrfs_release_path(path);
1012         if (drop_end)
1013                 *drop_end = found ? min(end, extent_end) : end;
1014         return ret;
1015 }
1016 
1017 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
1018                        struct btrfs_root *root, struct inode *inode, u64 start,
1019                        u64 end, int drop_cache)
1020 {
1021         struct btrfs_path *path;
1022         int ret;
1023 
1024         path = btrfs_alloc_path();
1025         if (!path)
1026                 return -ENOMEM;
1027         ret = __btrfs_drop_extents(trans, root, inode, path, start, end, NULL,
1028                                    drop_cache, 0, 0, NULL);
1029         btrfs_free_path(path);
1030         return ret;
1031 }
1032 
1033 static int extent_mergeable(struct extent_buffer *leaf, int slot,
1034                             u64 objectid, u64 bytenr, u64 orig_offset,
1035                             u64 *start, u64 *end)
1036 {
1037         struct btrfs_file_extent_item *fi;
1038         struct btrfs_key key;
1039         u64 extent_end;
1040 
1041         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
1042                 return 0;
1043 
1044         btrfs_item_key_to_cpu(leaf, &key, slot);
1045         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
1046                 return 0;
1047 
1048         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1049         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
1050             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
1051             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
1052             btrfs_file_extent_compression(leaf, fi) ||
1053             btrfs_file_extent_encryption(leaf, fi) ||
1054             btrfs_file_extent_other_encoding(leaf, fi))
1055                 return 0;
1056 
1057         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1058         if ((*start && *start != key.offset) || (*end && *end != extent_end))
1059                 return 0;
1060 
1061         *start = key.offset;
1062         *end = extent_end;
1063         return 1;
1064 }
1065 
1066 /*
1067  * Mark extent in the range start - end as written.
1068  *
1069  * This changes extent type from 'pre-allocated' to 'regular'. If only
1070  * part of extent is marked as written, the extent will be split into
1071  * two or three.
1072  */
1073 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
1074                               struct inode *inode, u64 start, u64 end)
1075 {
1076         struct btrfs_root *root = BTRFS_I(inode)->root;
1077         struct extent_buffer *leaf;
1078         struct btrfs_path *path;
1079         struct btrfs_file_extent_item *fi;
1080         struct btrfs_key key;
1081         struct btrfs_key new_key;
1082         u64 bytenr;
1083         u64 num_bytes;
1084         u64 extent_end;
1085         u64 orig_offset;
1086         u64 other_start;
1087         u64 other_end;
1088         u64 split;
1089         int del_nr = 0;
1090         int del_slot = 0;
1091         int recow;
1092         int ret;
1093         u64 ino = btrfs_ino(inode);
1094 
1095         path = btrfs_alloc_path();
1096         if (!path)
1097                 return -ENOMEM;
1098 again:
1099         recow = 0;
1100         split = start;
1101         key.objectid = ino;
1102         key.type = BTRFS_EXTENT_DATA_KEY;
1103         key.offset = split;
1104 
1105         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1106         if (ret < 0)
1107                 goto out;
1108         if (ret > 0 && path->slots[0] > 0)
1109                 path->slots[0]--;
1110 
1111         leaf = path->nodes[0];
1112         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1113         BUG_ON(key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY);
1114         fi = btrfs_item_ptr(leaf, path->slots[0],
1115                             struct btrfs_file_extent_item);
1116         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
1117                BTRFS_FILE_EXTENT_PREALLOC);
1118         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1119         BUG_ON(key.offset > start || extent_end < end);
1120 
1121         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1122         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1123         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
1124         memcpy(&new_key, &key, sizeof(new_key));
1125 
1126         if (start == key.offset && end < extent_end) {
1127                 other_start = 0;
1128                 other_end = start;
1129                 if (extent_mergeable(leaf, path->slots[0] - 1,
1130                                      ino, bytenr, orig_offset,
1131                                      &other_start, &other_end)) {
1132                         new_key.offset = end;
1133                         btrfs_set_item_key_safe(root->fs_info, path, &new_key);
1134                         fi = btrfs_item_ptr(leaf, path->slots[0],
1135                                             struct btrfs_file_extent_item);
1136                         btrfs_set_file_extent_generation(leaf, fi,
1137                                                          trans->transid);
1138                         btrfs_set_file_extent_num_bytes(leaf, fi,
1139                                                         extent_end - end);
1140                         btrfs_set_file_extent_offset(leaf, fi,
1141                                                      end - orig_offset);
1142                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1143                                             struct btrfs_file_extent_item);
1144                         btrfs_set_file_extent_generation(leaf, fi,
1145                                                          trans->transid);
1146                         btrfs_set_file_extent_num_bytes(leaf, fi,
1147                                                         end - other_start);
1148                         btrfs_mark_buffer_dirty(leaf);
1149                         goto out;
1150                 }
1151         }
1152 
1153         if (start > key.offset && end == extent_end) {
1154                 other_start = end;
1155                 other_end = 0;
1156                 if (extent_mergeable(leaf, path->slots[0] + 1,
1157                                      ino, bytenr, orig_offset,
1158                                      &other_start, &other_end)) {
1159                         fi = btrfs_item_ptr(leaf, path->slots[0],
1160                                             struct btrfs_file_extent_item);
1161                         btrfs_set_file_extent_num_bytes(leaf, fi,
1162                                                         start - key.offset);
1163                         btrfs_set_file_extent_generation(leaf, fi,
1164                                                          trans->transid);
1165                         path->slots[0]++;
1166                         new_key.offset = start;
1167                         btrfs_set_item_key_safe(root->fs_info, path, &new_key);
1168 
1169                         fi = btrfs_item_ptr(leaf, path->slots[0],
1170                                             struct btrfs_file_extent_item);
1171                         btrfs_set_file_extent_generation(leaf, fi,
1172                                                          trans->transid);
1173                         btrfs_set_file_extent_num_bytes(leaf, fi,
1174                                                         other_end - start);
1175                         btrfs_set_file_extent_offset(leaf, fi,
1176                                                      start - orig_offset);
1177                         btrfs_mark_buffer_dirty(leaf);
1178                         goto out;
1179                 }
1180         }
1181 
1182         while (start > key.offset || end < extent_end) {
1183                 if (key.offset == start)
1184                         split = end;
1185 
1186                 new_key.offset = split;
1187                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
1188                 if (ret == -EAGAIN) {
1189                         btrfs_release_path(path);
1190                         goto again;
1191                 }
1192                 if (ret < 0) {
1193                         btrfs_abort_transaction(trans, root, ret);
1194                         goto out;
1195                 }
1196 
1197                 leaf = path->nodes[0];
1198                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1199                                     struct btrfs_file_extent_item);
1200                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1201                 btrfs_set_file_extent_num_bytes(leaf, fi,
1202                                                 split - key.offset);
1203 
1204                 fi = btrfs_item_ptr(leaf, path->slots[0],
1205                                     struct btrfs_file_extent_item);
1206 
1207                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1208                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
1209                 btrfs_set_file_extent_num_bytes(leaf, fi,
1210                                                 extent_end - split);
1211                 btrfs_mark_buffer_dirty(leaf);
1212 
1213                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
1214                                            root->root_key.objectid,
1215                                            ino, orig_offset);
1216                 BUG_ON(ret); /* -ENOMEM */
1217 
1218                 if (split == start) {
1219                         key.offset = start;
1220                 } else {
1221                         BUG_ON(start != key.offset);
1222                         path->slots[0]--;
1223                         extent_end = end;
1224                 }
1225                 recow = 1;
1226         }
1227 
1228         other_start = end;
1229         other_end = 0;
1230         if (extent_mergeable(leaf, path->slots[0] + 1,
1231                              ino, bytenr, orig_offset,
1232                              &other_start, &other_end)) {
1233                 if (recow) {
1234                         btrfs_release_path(path);
1235                         goto again;
1236                 }
1237                 extent_end = other_end;
1238                 del_slot = path->slots[0] + 1;
1239                 del_nr++;
1240                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1241                                         0, root->root_key.objectid,
1242                                         ino, orig_offset);
1243                 BUG_ON(ret); /* -ENOMEM */
1244         }
1245         other_start = 0;
1246         other_end = start;
1247         if (extent_mergeable(leaf, path->slots[0] - 1,
1248                              ino, bytenr, orig_offset,
1249                              &other_start, &other_end)) {
1250                 if (recow) {
1251                         btrfs_release_path(path);
1252                         goto again;
1253                 }
1254                 key.offset = other_start;
1255                 del_slot = path->slots[0];
1256                 del_nr++;
1257                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1258                                         0, root->root_key.objectid,
1259                                         ino, orig_offset);
1260                 BUG_ON(ret); /* -ENOMEM */
1261         }
1262         if (del_nr == 0) {
1263                 fi = btrfs_item_ptr(leaf, path->slots[0],
1264                            struct btrfs_file_extent_item);
1265                 btrfs_set_file_extent_type(leaf, fi,
1266                                            BTRFS_FILE_EXTENT_REG);
1267                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1268                 btrfs_mark_buffer_dirty(leaf);
1269         } else {
1270                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1271                            struct btrfs_file_extent_item);
1272                 btrfs_set_file_extent_type(leaf, fi,
1273                                            BTRFS_FILE_EXTENT_REG);
1274                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1275                 btrfs_set_file_extent_num_bytes(leaf, fi,
1276                                                 extent_end - key.offset);
1277                 btrfs_mark_buffer_dirty(leaf);
1278 
1279                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1280                 if (ret < 0) {
1281                         btrfs_abort_transaction(trans, root, ret);
1282                         goto out;
1283                 }
1284         }
1285 out:
1286         btrfs_free_path(path);
1287         return 0;
1288 }
1289 
1290 /*
1291  * on error we return an unlocked page and the error value
1292  * on success we return a locked page and 0
1293  */
1294 static int prepare_uptodate_page(struct inode *inode,
1295                                  struct page *page, u64 pos,
1296                                  bool force_uptodate)
1297 {
1298         int ret = 0;
1299 
1300         if (((pos & (PAGE_SIZE - 1)) || force_uptodate) &&
1301             !PageUptodate(page)) {
1302                 ret = btrfs_readpage(NULL, page);
1303                 if (ret)
1304                         return ret;
1305                 lock_page(page);
1306                 if (!PageUptodate(page)) {
1307                         unlock_page(page);
1308                         return -EIO;
1309                 }
1310                 if (page->mapping != inode->i_mapping) {
1311                         unlock_page(page);
1312                         return -EAGAIN;
1313                 }
1314         }
1315         return 0;
1316 }
1317 
1318 /*
1319  * this just gets pages into the page cache and locks them down.
1320  */
1321 static noinline int prepare_pages(struct inode *inode, struct page **pages,
1322                                   size_t num_pages, loff_t pos,
1323                                   size_t write_bytes, bool force_uptodate)
1324 {
1325         int i;
1326         unsigned long index = pos >> PAGE_SHIFT;
1327         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1328         int err = 0;
1329         int faili;
1330 
1331         for (i = 0; i < num_pages; i++) {
1332 again:
1333                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1334                                                mask | __GFP_WRITE);
1335                 if (!pages[i]) {
1336                         faili = i - 1;
1337                         err = -ENOMEM;
1338                         goto fail;
1339                 }
1340 
1341                 if (i == 0)
1342                         err = prepare_uptodate_page(inode, pages[i], pos,
1343                                                     force_uptodate);
1344                 if (!err && i == num_pages - 1)
1345                         err = prepare_uptodate_page(inode, pages[i],
1346                                                     pos + write_bytes, false);
1347                 if (err) {
1348                         put_page(pages[i]);
1349                         if (err == -EAGAIN) {
1350                                 err = 0;
1351                                 goto again;
1352                         }
1353                         faili = i - 1;
1354                         goto fail;
1355                 }
1356                 wait_on_page_writeback(pages[i]);
1357         }
1358 
1359         return 0;
1360 fail:
1361         while (faili >= 0) {
1362                 unlock_page(pages[faili]);
1363                 put_page(pages[faili]);
1364                 faili--;
1365         }
1366         return err;
1367 
1368 }
1369 
1370 /*
1371  * This function locks the extent and properly waits for data=ordered extents
1372  * to finish before allowing the pages to be modified if need.
1373  *
1374  * The return value:
1375  * 1 - the extent is locked
1376  * 0 - the extent is not locked, and everything is OK
1377  * -EAGAIN - need re-prepare the pages
1378  * the other < 0 number - Something wrong happens
1379  */
1380 static noinline int
1381 lock_and_cleanup_extent_if_need(struct inode *inode, struct page **pages,
1382                                 size_t num_pages, loff_t pos,
1383                                 size_t write_bytes,
1384                                 u64 *lockstart, u64 *lockend,
1385                                 struct extent_state **cached_state)
1386 {
1387         struct btrfs_root *root = BTRFS_I(inode)->root;
1388         u64 start_pos;
1389         u64 last_pos;
1390         int i;
1391         int ret = 0;
1392 
1393         start_pos = round_down(pos, root->sectorsize);
1394         last_pos = start_pos
1395                 + round_up(pos + write_bytes - start_pos, root->sectorsize) - 1;
1396 
1397         if (start_pos < inode->i_size) {
1398                 struct btrfs_ordered_extent *ordered;
1399                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
1400                                  start_pos, last_pos, cached_state);
1401                 ordered = btrfs_lookup_ordered_range(inode, start_pos,
1402                                                      last_pos - start_pos + 1);
1403                 if (ordered &&
1404                     ordered->file_offset + ordered->len > start_pos &&
1405                     ordered->file_offset <= last_pos) {
1406                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1407                                              start_pos, last_pos,
1408                                              cached_state, GFP_NOFS);
1409                         for (i = 0; i < num_pages; i++) {
1410                                 unlock_page(pages[i]);
1411                                 put_page(pages[i]);
1412                         }
1413                         btrfs_start_ordered_extent(inode, ordered, 1);
1414                         btrfs_put_ordered_extent(ordered);
1415                         return -EAGAIN;
1416                 }
1417                 if (ordered)
1418                         btrfs_put_ordered_extent(ordered);
1419 
1420                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1421                                   last_pos, EXTENT_DIRTY | EXTENT_DELALLOC |
1422                                   EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
1423                                   0, 0, cached_state, GFP_NOFS);
1424                 *lockstart = start_pos;
1425                 *lockend = last_pos;
1426                 ret = 1;
1427         }
1428 
1429         for (i = 0; i < num_pages; i++) {
1430                 if (clear_page_dirty_for_io(pages[i]))
1431                         account_page_redirty(pages[i]);
1432                 set_page_extent_mapped(pages[i]);
1433                 WARN_ON(!PageLocked(pages[i]));
1434         }
1435 
1436         return ret;
1437 }
1438 
1439 static noinline int check_can_nocow(struct inode *inode, loff_t pos,
1440                                     size_t *write_bytes)
1441 {
1442         struct btrfs_root *root = BTRFS_I(inode)->root;
1443         struct btrfs_ordered_extent *ordered;
1444         u64 lockstart, lockend;
1445         u64 num_bytes;
1446         int ret;
1447 
1448         ret = btrfs_start_write_no_snapshoting(root);
1449         if (!ret)
1450                 return -ENOSPC;
1451 
1452         lockstart = round_down(pos, root->sectorsize);
1453         lockend = round_up(pos + *write_bytes, root->sectorsize) - 1;
1454 
1455         while (1) {
1456                 lock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1457                 ordered = btrfs_lookup_ordered_range(inode, lockstart,
1458                                                      lockend - lockstart + 1);
1459                 if (!ordered) {
1460                         break;
1461                 }
1462                 unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1463                 btrfs_start_ordered_extent(inode, ordered, 1);
1464                 btrfs_put_ordered_extent(ordered);
1465         }
1466 
1467         num_bytes = lockend - lockstart + 1;
1468         ret = can_nocow_extent(inode, lockstart, &num_bytes, NULL, NULL, NULL);
1469         if (ret <= 0) {
1470                 ret = 0;
1471                 btrfs_end_write_no_snapshoting(root);
1472         } else {
1473                 *write_bytes = min_t(size_t, *write_bytes ,
1474                                      num_bytes - pos + lockstart);
1475         }
1476 
1477         unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1478 
1479         return ret;
1480 }
1481 
1482 static noinline ssize_t __btrfs_buffered_write(struct file *file,
1483                                                struct iov_iter *i,
1484                                                loff_t pos)
1485 {
1486         struct inode *inode = file_inode(file);
1487         struct btrfs_root *root = BTRFS_I(inode)->root;
1488         struct page **pages = NULL;
1489         struct extent_state *cached_state = NULL;
1490         u64 release_bytes = 0;
1491         u64 lockstart;
1492         u64 lockend;
1493         size_t num_written = 0;
1494         int nrptrs;
1495         int ret = 0;
1496         bool only_release_metadata = false;
1497         bool force_page_uptodate = false;
1498         bool need_unlock;
1499 
1500         nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE),
1501                         PAGE_SIZE / (sizeof(struct page *)));
1502         nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1503         nrptrs = max(nrptrs, 8);
1504         pages = kmalloc_array(nrptrs, sizeof(struct page *), GFP_KERNEL);
1505         if (!pages)
1506                 return -ENOMEM;
1507 
1508         while (iov_iter_count(i) > 0) {
1509                 size_t offset = pos & (PAGE_SIZE - 1);
1510                 size_t sector_offset;
1511                 size_t write_bytes = min(iov_iter_count(i),
1512                                          nrptrs * (size_t)PAGE_SIZE -
1513                                          offset);
1514                 size_t num_pages = DIV_ROUND_UP(write_bytes + offset,
1515                                                 PAGE_SIZE);
1516                 size_t reserve_bytes;
1517                 size_t dirty_pages;
1518                 size_t copied;
1519                 size_t dirty_sectors;
1520                 size_t num_sectors;
1521 
1522                 WARN_ON(num_pages > nrptrs);
1523 
1524                 /*
1525                  * Fault pages before locking them in prepare_pages
1526                  * to avoid recursive lock
1527                  */
1528                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1529                         ret = -EFAULT;
1530                         break;
1531                 }
1532 
1533                 sector_offset = pos & (root->sectorsize - 1);
1534                 reserve_bytes = round_up(write_bytes + sector_offset,
1535                                 root->sectorsize);
1536 
1537                 if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
1538                                               BTRFS_INODE_PREALLOC)) &&
1539                     check_can_nocow(inode, pos, &write_bytes) > 0) {
1540                         /*
1541                          * For nodata cow case, no need to reserve
1542                          * data space.
1543                          */
1544                         only_release_metadata = true;
1545                         /*
1546                          * our prealloc extent may be smaller than
1547                          * write_bytes, so scale down.
1548                          */
1549                         num_pages = DIV_ROUND_UP(write_bytes + offset,
1550                                                  PAGE_SIZE);
1551                         reserve_bytes = round_up(write_bytes + sector_offset,
1552                                         root->sectorsize);
1553                         goto reserve_metadata;
1554                 }
1555 
1556                 ret = btrfs_check_data_free_space(inode, pos, write_bytes);
1557                 if (ret < 0)
1558                         break;
1559 
1560 reserve_metadata:
1561                 ret = btrfs_delalloc_reserve_metadata(inode, reserve_bytes);
1562                 if (ret) {
1563                         if (!only_release_metadata)
1564                                 btrfs_free_reserved_data_space(inode, pos,
1565                                                                write_bytes);
1566                         else
1567                                 btrfs_end_write_no_snapshoting(root);
1568                         break;
1569                 }
1570 
1571                 release_bytes = reserve_bytes;
1572                 need_unlock = false;
1573 again:
1574                 /*
1575                  * This is going to setup the pages array with the number of
1576                  * pages we want, so we don't really need to worry about the
1577                  * contents of pages from loop to loop
1578                  */
1579                 ret = prepare_pages(inode, pages, num_pages,
1580                                     pos, write_bytes,
1581                                     force_page_uptodate);
1582                 if (ret)
1583                         break;
1584 
1585                 ret = lock_and_cleanup_extent_if_need(inode, pages, num_pages,
1586                                                 pos, write_bytes, &lockstart,
1587                                                 &lockend, &cached_state);
1588                 if (ret < 0) {
1589                         if (ret == -EAGAIN)
1590                                 goto again;
1591                         break;
1592                 } else if (ret > 0) {
1593                         need_unlock = true;
1594                         ret = 0;
1595                 }
1596 
1597                 copied = btrfs_copy_from_user(pos, write_bytes, pages, i);
1598 
1599                 num_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
1600                                                 reserve_bytes);
1601                 dirty_sectors = round_up(copied + sector_offset,
1602                                         root->sectorsize);
1603                 dirty_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
1604                                                 dirty_sectors);
1605 
1606                 /*
1607                  * if we have trouble faulting in the pages, fall
1608                  * back to one page at a time
1609                  */
1610                 if (copied < write_bytes)
1611                         nrptrs = 1;
1612 
1613                 if (copied == 0) {
1614                         force_page_uptodate = true;
1615                         dirty_sectors = 0;
1616                         dirty_pages = 0;
1617                 } else {
1618                         force_page_uptodate = false;
1619                         dirty_pages = DIV_ROUND_UP(copied + offset,
1620                                                    PAGE_SIZE);
1621                 }
1622 
1623                 /*
1624                  * If we had a short copy we need to release the excess delaloc
1625                  * bytes we reserved.  We need to increment outstanding_extents
1626                  * because btrfs_delalloc_release_space and
1627                  * btrfs_delalloc_release_metadata will decrement it, but
1628                  * we still have an outstanding extent for the chunk we actually
1629                  * managed to copy.
1630                  */
1631                 if (num_sectors > dirty_sectors) {
1632                         /*
1633                          * we round down because we don't want to count
1634                          * any partial blocks actually sent through the
1635                          * IO machines
1636                          */
1637                         release_bytes = round_down(release_bytes - copied,
1638                                       root->sectorsize);
1639                         if (copied > 0) {
1640                                 spin_lock(&BTRFS_I(inode)->lock);
1641                                 BTRFS_I(inode)->outstanding_extents++;
1642                                 spin_unlock(&BTRFS_I(inode)->lock);
1643                         }
1644                         if (only_release_metadata) {
1645                                 btrfs_delalloc_release_metadata(inode,
1646                                                                 release_bytes);
1647                         } else {
1648                                 u64 __pos;
1649 
1650                                 __pos = round_down(pos, root->sectorsize) +
1651                                         (dirty_pages << PAGE_SHIFT);
1652                                 btrfs_delalloc_release_space(inode, __pos,
1653                                                              release_bytes);
1654                         }
1655                 }
1656 
1657                 release_bytes = round_up(copied + sector_offset,
1658                                         root->sectorsize);
1659 
1660                 if (copied > 0)
1661                         ret = btrfs_dirty_pages(root, inode, pages,
1662                                                 dirty_pages, pos, copied,
1663                                                 NULL);
1664                 if (need_unlock)
1665                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1666                                              lockstart, lockend, &cached_state,
1667                                              GFP_NOFS);
1668                 if (ret) {
1669                         btrfs_drop_pages(pages, num_pages);
1670                         break;
1671                 }
1672 
1673                 release_bytes = 0;
1674                 if (only_release_metadata)
1675                         btrfs_end_write_no_snapshoting(root);
1676 
1677                 if (only_release_metadata && copied > 0) {
1678                         lockstart = round_down(pos, root->sectorsize);
1679                         lockend = round_up(pos + copied, root->sectorsize) - 1;
1680 
1681                         set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
1682                                        lockend, EXTENT_NORESERVE, NULL,
1683                                        NULL, GFP_NOFS);
1684                         only_release_metadata = false;
1685                 }
1686 
1687                 btrfs_drop_pages(pages, num_pages);
1688 
1689                 cond_resched();
1690 
1691                 balance_dirty_pages_ratelimited(inode->i_mapping);
1692                 if (dirty_pages < (root->nodesize >> PAGE_SHIFT) + 1)
1693                         btrfs_btree_balance_dirty(root);
1694 
1695                 pos += copied;
1696                 num_written += copied;
1697         }
1698 
1699         kfree(pages);
1700 
1701         if (release_bytes) {
1702                 if (only_release_metadata) {
1703                         btrfs_end_write_no_snapshoting(root);
1704                         btrfs_delalloc_release_metadata(inode, release_bytes);
1705                 } else {
1706                         btrfs_delalloc_release_space(inode, pos, release_bytes);
1707                 }
1708         }
1709 
1710         return num_written ? num_written : ret;
1711 }
1712 
1713 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
1714                                     struct iov_iter *from,
1715                                     loff_t pos)
1716 {
1717         struct file *file = iocb->ki_filp;
1718         struct inode *inode = file_inode(file);
1719         ssize_t written;
1720         ssize_t written_buffered;
1721         loff_t endbyte;
1722         int err;
1723 
1724         written = generic_file_direct_write(iocb, from, pos);
1725 
1726         if (written < 0 || !iov_iter_count(from))
1727                 return written;
1728 
1729         pos += written;
1730         written_buffered = __btrfs_buffered_write(file, from, pos);
1731         if (written_buffered < 0) {
1732                 err = written_buffered;
1733                 goto out;
1734         }
1735         /*
1736          * Ensure all data is persisted. We want the next direct IO read to be
1737          * able to read what was just written.
1738          */
1739         endbyte = pos + written_buffered - 1;
1740         err = btrfs_fdatawrite_range(inode, pos, endbyte);
1741         if (err)
1742                 goto out;
1743         err = filemap_fdatawait_range(inode->i_mapping, pos, endbyte);
1744         if (err)
1745                 goto out;
1746         written += written_buffered;
1747         iocb->ki_pos = pos + written_buffered;
1748         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_SHIFT,
1749                                  endbyte >> PAGE_SHIFT);
1750 out:
1751         return written ? written : err;
1752 }
1753 
1754 static void update_time_for_write(struct inode *inode)
1755 {
1756         struct timespec now;
1757 
1758         if (IS_NOCMTIME(inode))
1759                 return;
1760 
1761         now = current_fs_time(inode->i_sb);
1762         if (!timespec_equal(&inode->i_mtime, &now))
1763                 inode->i_mtime = now;
1764 
1765         if (!timespec_equal(&inode->i_ctime, &now))
1766                 inode->i_ctime = now;
1767 
1768         if (IS_I_VERSION(inode))
1769                 inode_inc_iversion(inode);
1770 }
1771 
1772 static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
1773                                     struct iov_iter *from)
1774 {
1775         struct file *file = iocb->ki_filp;
1776         struct inode *inode = file_inode(file);
1777         struct btrfs_root *root = BTRFS_I(inode)->root;
1778         u64 start_pos;
1779         u64 end_pos;
1780         ssize_t num_written = 0;
1781         bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
1782         ssize_t err;
1783         loff_t pos;
1784         size_t count;
1785         loff_t oldsize;
1786         int clean_page = 0;
1787 
1788         inode_lock(inode);
1789         err = generic_write_checks(iocb, from);
1790         if (err <= 0) {
1791                 inode_unlock(inode);
1792                 return err;
1793         }
1794 
1795         current->backing_dev_info = inode_to_bdi(inode);
1796         err = file_remove_privs(file);
1797         if (err) {
1798                 inode_unlock(inode);
1799                 goto out;
1800         }
1801 
1802         /*
1803          * If BTRFS flips readonly due to some impossible error
1804          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1805          * although we have opened a file as writable, we have
1806          * to stop this write operation to ensure FS consistency.
1807          */
1808         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
1809                 inode_unlock(inode);
1810                 err = -EROFS;
1811                 goto out;
1812         }
1813 
1814         /*
1815          * We reserve space for updating the inode when we reserve space for the
1816          * extent we are going to write, so we will enospc out there.  We don't
1817          * need to start yet another transaction to update the inode as we will
1818          * update the inode when we finish writing whatever data we write.
1819          */
1820         update_time_for_write(inode);
1821 
1822         pos = iocb->ki_pos;
1823         count = iov_iter_count(from);
1824         start_pos = round_down(pos, root->sectorsize);
1825         oldsize = i_size_read(inode);
1826         if (start_pos > oldsize) {
1827                 /* Expand hole size to cover write data, preventing empty gap */
1828                 end_pos = round_up(pos + count, root->sectorsize);
1829                 err = btrfs_cont_expand(inode, oldsize, end_pos);
1830                 if (err) {
1831                         inode_unlock(inode);
1832                         goto out;
1833                 }
1834                 if (start_pos > round_up(oldsize, root->sectorsize))
1835                         clean_page = 1;
1836         }
1837 
1838         if (sync)
1839                 atomic_inc(&BTRFS_I(inode)->sync_writers);
1840 
1841         if (iocb->ki_flags & IOCB_DIRECT) {
1842                 num_written = __btrfs_direct_write(iocb, from, pos);
1843         } else {
1844                 num_written = __btrfs_buffered_write(file, from, pos);
1845                 if (num_written > 0)
1846                         iocb->ki_pos = pos + num_written;
1847                 if (clean_page)
1848                         pagecache_isize_extended(inode, oldsize,
1849                                                 i_size_read(inode));
1850         }
1851 
1852         inode_unlock(inode);
1853 
1854         /*
1855          * We also have to set last_sub_trans to the current log transid,
1856          * otherwise subsequent syncs to a file that's been synced in this
1857          * transaction will appear to have already occurred.
1858          */
1859         spin_lock(&BTRFS_I(inode)->lock);
1860         BTRFS_I(inode)->last_sub_trans = root->log_transid;
1861         spin_unlock(&BTRFS_I(inode)->lock);
1862         if (num_written > 0) {
1863                 err = generic_write_sync(file, pos, num_written);
1864                 if (err < 0)
1865                         num_written = err;
1866         }
1867 
1868         if (sync)
1869                 atomic_dec(&BTRFS_I(inode)->sync_writers);
1870 out:
1871         current->backing_dev_info = NULL;
1872         return num_written ? num_written : err;
1873 }
1874 
1875 int btrfs_release_file(struct inode *inode, struct file *filp)
1876 {
1877         if (filp->private_data)
1878                 btrfs_ioctl_trans_end(filp);
1879         /*
1880          * ordered_data_close is set by settattr when we are about to truncate
1881          * a file from a non-zero size to a zero size.  This tries to
1882          * flush down new bytes that may have been written if the
1883          * application were using truncate to replace a file in place.
1884          */
1885         if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
1886                                &BTRFS_I(inode)->runtime_flags))
1887                         filemap_flush(inode->i_mapping);
1888         return 0;
1889 }
1890 
1891 static int start_ordered_ops(struct inode *inode, loff_t start, loff_t end)
1892 {
1893         int ret;
1894 
1895         atomic_inc(&BTRFS_I(inode)->sync_writers);
1896         ret = btrfs_fdatawrite_range(inode, start, end);
1897         atomic_dec(&BTRFS_I(inode)->sync_writers);
1898 
1899         return ret;
1900 }
1901 
1902 /*
1903  * fsync call for both files and directories.  This logs the inode into
1904  * the tree log instead of forcing full commits whenever possible.
1905  *
1906  * It needs to call filemap_fdatawait so that all ordered extent updates are
1907  * in the metadata btree are up to date for copying to the log.
1908  *
1909  * It drops the inode mutex before doing the tree log commit.  This is an
1910  * important optimization for directories because holding the mutex prevents
1911  * new operations on the dir while we write to disk.
1912  */
1913 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
1914 {
1915         struct dentry *dentry = file_dentry(file);
1916         struct inode *inode = d_inode(dentry);
1917         struct btrfs_root *root = BTRFS_I(inode)->root;
1918         struct btrfs_trans_handle *trans;
1919         struct btrfs_log_ctx ctx;
1920         int ret = 0;
1921         bool full_sync = 0;
1922         u64 len;
1923 
1924         /*
1925          * The range length can be represented by u64, we have to do the typecasts
1926          * to avoid signed overflow if it's [0, LLONG_MAX] eg. from fsync()
1927          */
1928         len = (u64)end - (u64)start + 1;
1929         trace_btrfs_sync_file(file, datasync);
1930 
1931         /*
1932          * We write the dirty pages in the range and wait until they complete
1933          * out of the ->i_mutex. If so, we can flush the dirty pages by
1934          * multi-task, and make the performance up.  See
1935          * btrfs_wait_ordered_range for an explanation of the ASYNC check.
1936          */
1937         ret = start_ordered_ops(inode, start, end);
1938         if (ret)
1939                 return ret;
1940 
1941         inode_lock(inode);
1942         atomic_inc(&root->log_batch);
1943         full_sync = test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
1944                              &BTRFS_I(inode)->runtime_flags);
1945         /*
1946          * We might have have had more pages made dirty after calling
1947          * start_ordered_ops and before acquiring the inode's i_mutex.
1948          */
1949         if (full_sync) {
1950                 /*
1951                  * For a full sync, we need to make sure any ordered operations
1952                  * start and finish before we start logging the inode, so that
1953                  * all extents are persisted and the respective file extent
1954                  * items are in the fs/subvol btree.
1955                  */
1956                 ret = btrfs_wait_ordered_range(inode, start, len);
1957         } else {
1958                 /*
1959                  * Start any new ordered operations before starting to log the
1960                  * inode. We will wait for them to finish in btrfs_sync_log().
1961                  *
1962                  * Right before acquiring the inode's mutex, we might have new
1963                  * writes dirtying pages, which won't immediately start the
1964                  * respective ordered operations - that is done through the
1965                  * fill_delalloc callbacks invoked from the writepage and
1966                  * writepages address space operations. So make sure we start
1967                  * all ordered operations before starting to log our inode. Not
1968                  * doing this means that while logging the inode, writeback
1969                  * could start and invoke writepage/writepages, which would call
1970                  * the fill_delalloc callbacks (cow_file_range,
1971                  * submit_compressed_extents). These callbacks add first an
1972                  * extent map to the modified list of extents and then create
1973                  * the respective ordered operation, which means in
1974                  * tree-log.c:btrfs_log_inode() we might capture all existing
1975                  * ordered operations (with btrfs_get_logged_extents()) before
1976                  * the fill_delalloc callback adds its ordered operation, and by
1977                  * the time we visit the modified list of extent maps (with
1978                  * btrfs_log_changed_extents()), we see and process the extent
1979                  * map they created. We then use the extent map to construct a
1980                  * file extent item for logging without waiting for the
1981                  * respective ordered operation to finish - this file extent
1982                  * item points to a disk location that might not have yet been
1983                  * written to, containing random data - so after a crash a log
1984                  * replay will make our inode have file extent items that point
1985                  * to disk locations containing invalid data, as we returned
1986                  * success to userspace without waiting for the respective
1987                  * ordered operation to finish, because it wasn't captured by
1988                  * btrfs_get_logged_extents().
1989                  */
1990                 ret = start_ordered_ops(inode, start, end);
1991         }
1992         if (ret) {
1993                 inode_unlock(inode);
1994                 goto out;
1995         }
1996         atomic_inc(&root->log_batch);
1997 
1998         /*
1999          * If the last transaction that changed this file was before the current
2000          * transaction and we have the full sync flag set in our inode, we can
2001          * bail out now without any syncing.
2002          *
2003          * Note that we can't bail out if the full sync flag isn't set. This is
2004          * because when the full sync flag is set we start all ordered extents
2005          * and wait for them to fully complete - when they complete they update
2006          * the inode's last_trans field through:
2007          *
2008          *     btrfs_finish_ordered_io() ->
2009          *         btrfs_update_inode_fallback() ->
2010          *             btrfs_update_inode() ->
2011          *                 btrfs_set_inode_last_trans()
2012          *
2013          * So we are sure that last_trans is up to date and can do this check to
2014          * bail out safely. For the fast path, when the full sync flag is not
2015          * set in our inode, we can not do it because we start only our ordered
2016          * extents and don't wait for them to complete (that is when
2017          * btrfs_finish_ordered_io runs), so here at this point their last_trans
2018          * value might be less than or equals to fs_info->last_trans_committed,
2019          * and setting a speculative last_trans for an inode when a buffered
2020          * write is made (such as fs_info->generation + 1 for example) would not
2021          * be reliable since after setting the value and before fsync is called
2022          * any number of transactions can start and commit (transaction kthread
2023          * commits the current transaction periodically), and a transaction
2024          * commit does not start nor waits for ordered extents to complete.
2025          */
2026         smp_mb();
2027         if (btrfs_inode_in_log(inode, root->fs_info->generation) ||
2028             (full_sync && BTRFS_I(inode)->last_trans <=
2029              root->fs_info->last_trans_committed) ||
2030             (!btrfs_have_ordered_extents_in_range(inode, start, len) &&
2031              BTRFS_I(inode)->last_trans
2032              <= root->fs_info->last_trans_committed)) {
2033                 /*
2034                  * We'v had everything committed since the last time we were
2035                  * modified so clear this flag in case it was set for whatever
2036                  * reason, it's no longer relevant.
2037                  */
2038                 clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2039                           &BTRFS_I(inode)->runtime_flags);
2040                 inode_unlock(inode);
2041                 goto out;
2042         }
2043 
2044         /*
2045          * ok we haven't committed the transaction yet, lets do a commit
2046          */
2047         if (file->private_data)
2048                 btrfs_ioctl_trans_end(file);
2049 
2050         /*
2051          * We use start here because we will need to wait on the IO to complete
2052          * in btrfs_sync_log, which could require joining a transaction (for
2053          * example checking cross references in the nocow path).  If we use join
2054          * here we could get into a situation where we're waiting on IO to
2055          * happen that is blocked on a transaction trying to commit.  With start
2056          * we inc the extwriter counter, so we wait for all extwriters to exit
2057          * before we start blocking join'ers.  This comment is to keep somebody
2058          * from thinking they are super smart and changing this to
2059          * btrfs_join_transaction *cough*Josef*cough*.
2060          */
2061         trans = btrfs_start_transaction(root, 0);
2062         if (IS_ERR(trans)) {
2063                 ret = PTR_ERR(trans);
2064                 inode_unlock(inode);
2065                 goto out;
2066         }
2067         trans->sync = true;
2068 
2069         btrfs_init_log_ctx(&ctx);
2070 
2071         ret = btrfs_log_dentry_safe(trans, root, dentry, start, end, &ctx);
2072         if (ret < 0) {
2073                 /* Fallthrough and commit/free transaction. */
2074                 ret = 1;
2075         }
2076 
2077         /* we've logged all the items and now have a consistent
2078          * version of the file in the log.  It is possible that
2079          * someone will come in and modify the file, but that's
2080          * fine because the log is consistent on disk, and we
2081          * have references to all of the file's extents
2082          *
2083          * It is possible that someone will come in and log the
2084          * file again, but that will end up using the synchronization
2085          * inside btrfs_sync_log to keep things safe.
2086          */
2087         inode_unlock(inode);
2088 
2089         /*
2090          * If any of the ordered extents had an error, just return it to user
2091          * space, so that the application knows some writes didn't succeed and
2092          * can take proper action (retry for e.g.). Blindly committing the
2093          * transaction in this case, would fool userspace that everything was
2094          * successful. And we also want to make sure our log doesn't contain
2095          * file extent items pointing to extents that weren't fully written to -
2096          * just like in the non fast fsync path, where we check for the ordered
2097          * operation's error flag before writing to the log tree and return -EIO
2098          * if any of them had this flag set (btrfs_wait_ordered_range) -
2099          * therefore we need to check for errors in the ordered operations,
2100          * which are indicated by ctx.io_err.
2101          */
2102         if (ctx.io_err) {
2103                 btrfs_end_transaction(trans, root);
2104                 ret = ctx.io_err;
2105                 goto out;
2106         }
2107 
2108         if (ret != BTRFS_NO_LOG_SYNC) {
2109                 if (!ret) {
2110                         ret = btrfs_sync_log(trans, root, &ctx);
2111                         if (!ret) {
2112                                 ret = btrfs_end_transaction(trans, root);
2113                                 goto out;
2114                         }
2115                 }
2116                 if (!full_sync) {
2117                         ret = btrfs_wait_ordered_range(inode, start, len);
2118                         if (ret) {
2119                                 btrfs_end_transaction(trans, root);
2120                                 goto out;
2121                         }
2122                 }
2123                 ret = btrfs_commit_transaction(trans, root);
2124         } else {
2125                 ret = btrfs_end_transaction(trans, root);
2126         }
2127 out:
2128         return ret > 0 ? -EIO : ret;
2129 }
2130 
2131 static const struct vm_operations_struct btrfs_file_vm_ops = {
2132         .fault          = filemap_fault,
2133         .map_pages      = filemap_map_pages,
2134         .page_mkwrite   = btrfs_page_mkwrite,
2135 };
2136 
2137 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
2138 {
2139         struct address_space *mapping = filp->f_mapping;
2140 
2141         if (!mapping->a_ops->readpage)
2142                 return -ENOEXEC;
2143 
2144         file_accessed(filp);
2145         vma->vm_ops = &btrfs_file_vm_ops;
2146 
2147         return 0;
2148 }
2149 
2150 static int hole_mergeable(struct inode *inode, struct extent_buffer *leaf,
2151                           int slot, u64 start, u64 end)
2152 {
2153         struct btrfs_file_extent_item *fi;
2154         struct btrfs_key key;
2155 
2156         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
2157                 return 0;
2158 
2159         btrfs_item_key_to_cpu(leaf, &key, slot);
2160         if (key.objectid != btrfs_ino(inode) ||
2161             key.type != BTRFS_EXTENT_DATA_KEY)
2162                 return 0;
2163 
2164         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
2165 
2166         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
2167                 return 0;
2168 
2169         if (btrfs_file_extent_disk_bytenr(leaf, fi))
2170                 return 0;
2171 
2172         if (key.offset == end)
2173                 return 1;
2174         if (key.offset + btrfs_file_extent_num_bytes(leaf, fi) == start)
2175                 return 1;
2176         return 0;
2177 }
2178 
2179 static int fill_holes(struct btrfs_trans_handle *trans, struct inode *inode,
2180                       struct btrfs_path *path, u64 offset, u64 end)
2181 {
2182         struct btrfs_root *root = BTRFS_I(inode)->root;
2183         struct extent_buffer *leaf;
2184         struct btrfs_file_extent_item *fi;
2185         struct extent_map *hole_em;
2186         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2187         struct btrfs_key key;
2188         int ret;
2189 
2190         if (btrfs_fs_incompat(root->fs_info, NO_HOLES))
2191                 goto out;
2192 
2193         key.objectid = btrfs_ino(inode);
2194         key.type = BTRFS_EXTENT_DATA_KEY;
2195         key.offset = offset;
2196 
2197         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
2198         if (ret < 0)
2199                 return ret;
2200         BUG_ON(!ret);
2201 
2202         leaf = path->nodes[0];
2203         if (hole_mergeable(inode, leaf, path->slots[0]-1, offset, end)) {
2204                 u64 num_bytes;
2205 
2206                 path->slots[0]--;
2207                 fi = btrfs_item_ptr(leaf, path->slots[0],
2208                                     struct btrfs_file_extent_item);
2209                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) +
2210                         end - offset;
2211                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2212                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2213                 btrfs_set_file_extent_offset(leaf, fi, 0);
2214                 btrfs_mark_buffer_dirty(leaf);
2215                 goto out;
2216         }
2217 
2218         if (hole_mergeable(inode, leaf, path->slots[0], offset, end)) {
2219                 u64 num_bytes;
2220 
2221                 key.offset = offset;
2222                 btrfs_set_item_key_safe(root->fs_info, path, &key);
2223                 fi = btrfs_item_ptr(leaf, path->slots[0],
2224                                     struct btrfs_file_extent_item);
2225                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + end -
2226                         offset;
2227                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2228                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2229                 btrfs_set_file_extent_offset(leaf, fi, 0);
2230                 btrfs_mark_buffer_dirty(leaf);
2231                 goto out;
2232         }
2233         btrfs_release_path(path);
2234 
2235         ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode), offset,
2236                                        0, 0, end - offset, 0, end - offset,
2237                                        0, 0, 0);
2238         if (ret)
2239                 return ret;
2240 
2241 out:
2242         btrfs_release_path(path);
2243 
2244         hole_em = alloc_extent_map();
2245         if (!hole_em) {
2246                 btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2247                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2248                         &BTRFS_I(inode)->runtime_flags);
2249         } else {
2250                 hole_em->start = offset;
2251                 hole_em->len = end - offset;
2252                 hole_em->ram_bytes = hole_em->len;
2253                 hole_em->orig_start = offset;
2254 
2255                 hole_em->block_start = EXTENT_MAP_HOLE;
2256                 hole_em->block_len = 0;
2257                 hole_em->orig_block_len = 0;
2258                 hole_em->bdev = root->fs_info->fs_devices->latest_bdev;
2259                 hole_em->compress_type = BTRFS_COMPRESS_NONE;
2260                 hole_em->generation = trans->transid;
2261 
2262                 do {
2263                         btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2264                         write_lock(&em_tree->lock);
2265                         ret = add_extent_mapping(em_tree, hole_em, 1);
2266                         write_unlock(&em_tree->lock);
2267                 } while (ret == -EEXIST);
2268                 free_extent_map(hole_em);
2269                 if (ret)
2270                         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2271                                 &BTRFS_I(inode)->runtime_flags);
2272         }
2273 
2274         return 0;
2275 }
2276 
2277 /*
2278  * Find a hole extent on given inode and change start/len to the end of hole
2279  * extent.(hole/vacuum extent whose em->start <= start &&
2280  *         em->start + em->len > start)
2281  * When a hole extent is found, return 1 and modify start/len.
2282  */
2283 static int find_first_non_hole(struct inode *inode, u64 *start, u64 *len)
2284 {
2285         struct extent_map *em;
2286         int ret = 0;
2287 
2288         em = btrfs_get_extent(inode, NULL, 0, *start, *len, 0);
2289         if (IS_ERR_OR_NULL(em)) {
2290                 if (!em)
2291                         ret = -ENOMEM;
2292                 else
2293                         ret = PTR_ERR(em);
2294                 return ret;
2295         }
2296 
2297         /* Hole or vacuum extent(only exists in no-hole mode) */
2298         if (em->block_start == EXTENT_MAP_HOLE) {
2299                 ret = 1;
2300                 *len = em->start + em->len > *start + *len ?
2301                        0 : *start + *len - em->start - em->len;
2302                 *start = em->start + em->len;
2303         }
2304         free_extent_map(em);
2305         return ret;
2306 }
2307 
2308 static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
2309 {
2310         struct btrfs_root *root = BTRFS_I(inode)->root;
2311         struct extent_state *cached_state = NULL;
2312         struct btrfs_path *path;
2313         struct btrfs_block_rsv *rsv;
2314         struct btrfs_trans_handle *trans;
2315         u64 lockstart;
2316         u64 lockend;
2317         u64 tail_start;
2318         u64 tail_len;
2319         u64 orig_start = offset;
2320         u64 cur_offset;
2321         u64 min_size = btrfs_calc_trunc_metadata_size(root, 1);
2322         u64 drop_end;
2323         int ret = 0;
2324         int err = 0;
2325         unsigned int rsv_count;
2326         bool same_block;
2327         bool no_holes = btrfs_fs_incompat(root->fs_info, NO_HOLES);
2328         u64 ino_size;
2329         bool truncated_block = false;
2330         bool updated_inode = false;
2331 
2332         ret = btrfs_wait_ordered_range(inode, offset, len);
2333         if (ret)
2334                 return ret;
2335 
2336         inode_lock(inode);
2337         ino_size = round_up(inode->i_size, root->sectorsize);
2338         ret = find_first_non_hole(inode, &offset, &len);
2339         if (ret < 0)
2340                 goto out_only_mutex;
2341         if (ret && !len) {
2342                 /* Already in a large hole */
2343                 ret = 0;
2344                 goto out_only_mutex;
2345         }
2346 
2347         lockstart = round_up(offset, BTRFS_I(inode)->root->sectorsize);
2348         lockend = round_down(offset + len,
2349                              BTRFS_I(inode)->root->sectorsize) - 1;
2350         same_block = (BTRFS_BYTES_TO_BLKS(root->fs_info, offset))
2351                 == (BTRFS_BYTES_TO_BLKS(root->fs_info, offset + len - 1));
2352         /*
2353          * We needn't truncate any block which is beyond the end of the file
2354          * because we are sure there is no data there.
2355          */
2356         /*
2357          * Only do this if we are in the same block and we aren't doing the
2358          * entire block.
2359          */
2360         if (same_block && len < root->sectorsize) {
2361                 if (offset < ino_size) {
2362                         truncated_block = true;
2363                         ret = btrfs_truncate_block(inode, offset, len, 0);
2364                 } else {
2365                         ret = 0;
2366                 }
2367                 goto out_only_mutex;
2368         }
2369 
2370         /* zero back part of the first block */
2371         if (offset < ino_size) {
2372                 truncated_block = true;
2373                 ret = btrfs_truncate_block(inode, offset, 0, 0);
2374                 if (ret) {
2375                         inode_unlock(inode);
2376                         return ret;
2377                 }
2378         }
2379 
2380         /* Check the aligned pages after the first unaligned page,
2381          * if offset != orig_start, which means the first unaligned page
2382          * including serveral following pages are already in holes,
2383          * the extra check can be skipped */
2384         if (offset == orig_start) {
2385                 /* after truncate page, check hole again */
2386                 len = offset + len - lockstart;
2387                 offset = lockstart;
2388                 ret = find_first_non_hole(inode, &offset, &len);
2389                 if (ret < 0)
2390                         goto out_only_mutex;
2391                 if (ret && !len) {
2392                         ret = 0;
2393                         goto out_only_mutex;
2394                 }
2395                 lockstart = offset;
2396         }
2397 
2398         /* Check the tail unaligned part is in a hole */
2399         tail_start = lockend + 1;
2400         tail_len = offset + len - tail_start;
2401         if (tail_len) {
2402                 ret = find_first_non_hole(inode, &tail_start, &tail_len);
2403                 if (unlikely(ret < 0))
2404                         goto out_only_mutex;
2405                 if (!ret) {
2406                         /* zero the front end of the last page */
2407                         if (tail_start + tail_len < ino_size) {
2408                                 truncated_block = true;
2409                                 ret = btrfs_truncate_block(inode,
2410                                                         tail_start + tail_len,
2411                                                         0, 1);
2412                                 if (ret)
2413                                         goto out_only_mutex;
2414                         }
2415                 }
2416         }
2417 
2418         if (lockend < lockstart) {
2419                 ret = 0;
2420                 goto out_only_mutex;
2421         }
2422 
2423         while (1) {
2424                 struct btrfs_ordered_extent *ordered;
2425 
2426                 truncate_pagecache_range(inode, lockstart, lockend);
2427 
2428                 lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2429                                  &cached_state);
2430                 ordered = btrfs_lookup_first_ordered_extent(inode, lockend);
2431 
2432                 /*
2433                  * We need to make sure we have no ordered extents in this range
2434                  * and nobody raced in and read a page in this range, if we did
2435                  * we need to try again.
2436                  */
2437                 if ((!ordered ||
2438                     (ordered->file_offset + ordered->len <= lockstart ||
2439                      ordered->file_offset > lockend)) &&
2440                      !btrfs_page_exists_in_range(inode, lockstart, lockend)) {
2441                         if (ordered)
2442                                 btrfs_put_ordered_extent(ordered);
2443                         break;
2444                 }
2445                 if (ordered)
2446                         btrfs_put_ordered_extent(ordered);
2447                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
2448                                      lockend, &cached_state, GFP_NOFS);
2449                 ret = btrfs_wait_ordered_range(inode, lockstart,
2450                                                lockend - lockstart + 1);
2451                 if (ret) {
2452                         inode_unlock(inode);
2453                         return ret;
2454                 }
2455         }
2456 
2457         path = btrfs_alloc_path();
2458         if (!path) {
2459                 ret = -ENOMEM;
2460                 goto out;
2461         }
2462 
2463         rsv = btrfs_alloc_block_rsv(root, BTRFS_BLOCK_RSV_TEMP);
2464         if (!rsv) {
2465                 ret = -ENOMEM;
2466                 goto out_free;
2467         }
2468         rsv->size = btrfs_calc_trunc_metadata_size(root, 1);
2469         rsv->failfast = 1;
2470 
2471         /*
2472          * 1 - update the inode
2473          * 1 - removing the extents in the range
2474          * 1 - adding the hole extent if no_holes isn't set
2475          */
2476         rsv_count = no_holes ? 2 : 3;
2477         trans = btrfs_start_transaction(root, rsv_count);
2478         if (IS_ERR(trans)) {
2479                 err = PTR_ERR(trans);
2480                 goto out_free;
2481         }
2482 
2483         ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv, rsv,
2484                                       min_size);
2485         BUG_ON(ret);
2486         trans->block_rsv = rsv;
2487 
2488         cur_offset = lockstart;
2489         len = lockend - cur_offset;
2490         while (cur_offset < lockend) {
2491                 ret = __btrfs_drop_extents(trans, root, inode, path,
2492                                            cur_offset, lockend + 1,
2493                                            &drop_end, 1, 0, 0, NULL);
2494                 if (ret != -ENOSPC)
2495                         break;
2496 
2497                 trans->block_rsv = &root->fs_info->trans_block_rsv;
2498 
2499                 if (cur_offset < ino_size) {
2500                         ret = fill_holes(trans, inode, path, cur_offset,
2501                                          drop_end);
2502                         if (ret) {
2503                                 err = ret;
2504                                 break;
2505                         }
2506                 }
2507 
2508                 cur_offset = drop_end;
2509 
2510                 ret = btrfs_update_inode(trans, root, inode);
2511                 if (ret) {
2512                         err = ret;
2513                         break;
2514                 }
2515 
2516                 btrfs_end_transaction(trans, root);
2517                 btrfs_btree_balance_dirty(root);
2518 
2519                 trans = btrfs_start_transaction(root, rsv_count);
2520                 if (IS_ERR(trans)) {
2521                         ret = PTR_ERR(trans);
2522                         trans = NULL;
2523                         break;
2524                 }
2525 
2526                 ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv,
2527                                               rsv, min_size);
2528                 BUG_ON(ret);    /* shouldn't happen */
2529                 trans->block_rsv = rsv;
2530 
2531                 ret = find_first_non_hole(inode, &cur_offset, &len);
2532                 if (unlikely(ret < 0))
2533                         break;
2534                 if (ret && !len) {
2535                         ret = 0;
2536                         break;
2537                 }
2538         }
2539 
2540         if (ret) {
2541                 err = ret;
2542                 goto out_trans;
2543         }
2544 
2545         trans->block_rsv = &root->fs_info->trans_block_rsv;
2546         /*
2547          * If we are using the NO_HOLES feature we might have had already an
2548          * hole that overlaps a part of the region [lockstart, lockend] and
2549          * ends at (or beyond) lockend. Since we have no file extent items to
2550          * represent holes, drop_end can be less than lockend and so we must
2551          * make sure we have an extent map representing the existing hole (the
2552          * call to __btrfs_drop_extents() might have dropped the existing extent
2553          * map representing the existing hole), otherwise the fast fsync path
2554          * will not record the existence of the hole region
2555          * [existing_hole_start, lockend].
2556          */
2557         if (drop_end <= lockend)
2558                 drop_end = lockend + 1;
2559         /*
2560          * Don't insert file hole extent item if it's for a range beyond eof
2561          * (because it's useless) or if it represents a 0 bytes range (when
2562          * cur_offset == drop_end).
2563          */
2564         if (cur_offset < ino_size && cur_offset < drop_end) {
2565                 ret = fill_holes(trans, inode, path, cur_offset, drop_end);
2566                 if (ret) {
2567                         err = ret;
2568                         goto out_trans;
2569                 }
2570         }
2571 
2572 out_trans:
2573         if (!trans)
2574                 goto out_free;
2575 
2576         inode_inc_iversion(inode);
2577         inode->i_mtime = inode->i_ctime = current_fs_time(inode->i_sb);
2578 
2579         trans->block_rsv = &root->fs_info->trans_block_rsv;
2580         ret = btrfs_update_inode(trans, root, inode);
2581         updated_inode = true;
2582         btrfs_end_transaction(trans, root);
2583         btrfs_btree_balance_dirty(root);
2584 out_free:
2585         btrfs_free_path(path);
2586         btrfs_free_block_rsv(root, rsv);
2587 out:
2588         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2589                              &cached_state, GFP_NOFS);
2590 out_only_mutex:
2591         if (!updated_inode && truncated_block && !ret && !err) {
2592                 /*
2593                  * If we only end up zeroing part of a page, we still need to
2594                  * update the inode item, so that all the time fields are
2595                  * updated as well as the necessary btrfs inode in memory fields
2596                  * for detecting, at fsync time, if the inode isn't yet in the
2597                  * log tree or it's there but not up to date.
2598                  */
2599                 trans = btrfs_start_transaction(root, 1);
2600                 if (IS_ERR(trans)) {
2601                         err = PTR_ERR(trans);
2602                 } else {
2603                         err = btrfs_update_inode(trans, root, inode);
2604                         ret = btrfs_end_transaction(trans, root);
2605                 }
2606         }
2607         inode_unlock(inode);
2608         if (ret && !err)
2609                 err = ret;
2610         return err;
2611 }
2612 
2613 /* Helper structure to record which range is already reserved */
2614 struct falloc_range {
2615         struct list_head list;
2616         u64 start;
2617         u64 len;
2618 };
2619 
2620 /*
2621  * Helper function to add falloc range
2622  *
2623  * Caller should have locked the larger range of extent containing
2624  * [start, len)
2625  */
2626 static int add_falloc_range(struct list_head *head, u64 start, u64 len)
2627 {
2628         struct falloc_range *prev = NULL;
2629         struct falloc_range *range = NULL;
2630 
2631         if (list_empty(head))
2632                 goto insert;
2633 
2634         /*
2635          * As fallocate iterate by bytenr order, we only need to check
2636          * the last range.
2637          */
2638         prev = list_entry(head->prev, struct falloc_range, list);
2639         if (prev->start + prev->len == start) {
2640                 prev->len += len;
2641                 return 0;
2642         }
2643 insert:
2644         range = kmalloc(sizeof(*range), GFP_KERNEL);
2645         if (!range)
2646                 return -ENOMEM;
2647         range->start = start;
2648         range->len = len;
2649         list_add_tail(&range->list, head);
2650         return 0;
2651 }
2652 
2653 static long btrfs_fallocate(struct file *file, int mode,
2654                             loff_t offset, loff_t len)
2655 {
2656         struct inode *inode = file_inode(file);
2657         struct extent_state *cached_state = NULL;
2658         struct falloc_range *range;
2659         struct falloc_range *tmp;
2660         struct list_head reserve_list;
2661         u64 cur_offset;
2662         u64 last_byte;
2663         u64 alloc_start;
2664         u64 alloc_end;
2665         u64 alloc_hint = 0;
2666         u64 locked_end;
2667         u64 actual_end = 0;
2668         struct extent_map *em;
2669         int blocksize = BTRFS_I(inode)->root->sectorsize;
2670         int ret;
2671 
2672         alloc_start = round_down(offset, blocksize);
2673         alloc_end = round_up(offset + len, blocksize);
2674 
2675         /* Make sure we aren't being give some crap mode */
2676         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2677                 return -EOPNOTSUPP;
2678 
2679         if (mode & FALLOC_FL_PUNCH_HOLE)
2680                 return btrfs_punch_hole(inode, offset, len);
2681 
2682         /*
2683          * Only trigger disk allocation, don't trigger qgroup reserve
2684          *
2685          * For qgroup space, it will be checked later.
2686          */
2687         ret = btrfs_alloc_data_chunk_ondemand(inode, alloc_end - alloc_start);
2688         if (ret < 0)
2689                 return ret;
2690 
2691         inode_lock(inode);
2692 
2693         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) {
2694                 ret = inode_newsize_ok(inode, offset + len);
2695                 if (ret)
2696                         goto out;
2697         }
2698 
2699         /*
2700          * TODO: Move these two operations after we have checked
2701          * accurate reserved space, or fallocate can still fail but
2702          * with page truncated or size expanded.
2703          *
2704          * But that's a minor problem and won't do much harm BTW.
2705          */
2706         if (alloc_start > inode->i_size) {
2707                 ret = btrfs_cont_expand(inode, i_size_read(inode),
2708                                         alloc_start);
2709                 if (ret)
2710                         goto out;
2711         } else if (offset + len > inode->i_size) {
2712                 /*
2713                  * If we are fallocating from the end of the file onward we
2714                  * need to zero out the end of the block if i_size lands in the
2715                  * middle of a block.
2716                  */
2717                 ret = btrfs_truncate_block(inode, inode->i_size, 0, 0);
2718                 if (ret)
2719                         goto out;
2720         }
2721 
2722         /*
2723          * wait for ordered IO before we have any locks.  We'll loop again
2724          * below with the locks held.
2725          */
2726         ret = btrfs_wait_ordered_range(inode, alloc_start,
2727                                        alloc_end - alloc_start);
2728         if (ret)
2729                 goto out;
2730 
2731         locked_end = alloc_end - 1;
2732         while (1) {
2733                 struct btrfs_ordered_extent *ordered;
2734 
2735                 /* the extent lock is ordered inside the running
2736                  * transaction
2737                  */
2738                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
2739                                  locked_end, &cached_state);
2740                 ordered = btrfs_lookup_first_ordered_extent(inode,
2741                                                             alloc_end - 1);
2742                 if (ordered &&
2743                     ordered->file_offset + ordered->len > alloc_start &&
2744                     ordered->file_offset < alloc_end) {
2745                         btrfs_put_ordered_extent(ordered);
2746                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
2747                                              alloc_start, locked_end,
2748                                              &cached_state, GFP_KERNEL);
2749                         /*
2750                          * we can't wait on the range with the transaction
2751                          * running or with the extent lock held
2752                          */
2753                         ret = btrfs_wait_ordered_range(inode, alloc_start,
2754                                                        alloc_end - alloc_start);
2755                         if (ret)
2756                                 goto out;
2757                 } else {
2758                         if (ordered)
2759                                 btrfs_put_ordered_extent(ordered);
2760                         break;
2761                 }
2762         }
2763 
2764         /* First, check if we exceed the qgroup limit */
2765         INIT_LIST_HEAD(&reserve_list);
2766         cur_offset = alloc_start;
2767         while (1) {
2768                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
2769                                       alloc_end - cur_offset, 0);
2770                 if (IS_ERR_OR_NULL(em)) {
2771                         if (!em)
2772                                 ret = -ENOMEM;
2773                         else
2774                                 ret = PTR_ERR(em);
2775                         break;
2776                 }
2777                 last_byte = min(extent_map_end(em), alloc_end);
2778                 actual_end = min_t(u64, extent_map_end(em), offset + len);
2779                 last_byte = ALIGN(last_byte, blocksize);
2780                 if (em->block_start == EXTENT_MAP_HOLE ||
2781                     (cur_offset >= inode->i_size &&
2782                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
2783                         ret = add_falloc_range(&reserve_list, cur_offset,
2784                                                last_byte - cur_offset);
2785                         if (ret < 0) {
2786                                 free_extent_map(em);
2787                                 break;
2788                         }
2789                         ret = btrfs_qgroup_reserve_data(inode, cur_offset,
2790                                         last_byte - cur_offset);
2791                         if (ret < 0)
2792                                 break;
2793                 }
2794                 free_extent_map(em);
2795                 cur_offset = last_byte;
2796                 if (cur_offset >= alloc_end)
2797                         break;
2798         }
2799 
2800         /*
2801          * If ret is still 0, means we're OK to fallocate.
2802          * Or just cleanup the list and exit.
2803          */
2804         list_for_each_entry_safe(range, tmp, &reserve_list, list) {
2805                 if (!ret)
2806                         ret = btrfs_prealloc_file_range(inode, mode,
2807                                         range->start,
2808                                         range->len, 1 << inode->i_blkbits,
2809                                         offset + len, &alloc_hint);
2810                 list_del(&range->list);
2811                 kfree(range);
2812         }
2813         if (ret < 0)
2814                 goto out_unlock;
2815 
2816         if (actual_end > inode->i_size &&
2817             !(mode & FALLOC_FL_KEEP_SIZE)) {
2818                 struct btrfs_trans_handle *trans;
2819                 struct btrfs_root *root = BTRFS_I(inode)->root;
2820 
2821                 /*
2822                  * We didn't need to allocate any more space, but we
2823                  * still extended the size of the file so we need to
2824                  * update i_size and the inode item.
2825                  */
2826                 trans = btrfs_start_transaction(root, 1);
2827                 if (IS_ERR(trans)) {
2828                         ret = PTR_ERR(trans);
2829                 } else {
2830                         inode->i_ctime = current_fs_time(inode->i_sb);
2831                         i_size_write(inode, actual_end);
2832                         btrfs_ordered_update_i_size(inode, actual_end, NULL);
2833                         ret = btrfs_update_inode(trans, root, inode);
2834                         if (ret)
2835                                 btrfs_end_transaction(trans, root);
2836                         else
2837                                 ret = btrfs_end_transaction(trans, root);
2838                 }
2839         }
2840 out_unlock:
2841         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
2842                              &cached_state, GFP_KERNEL);
2843 out:
2844         /*
2845          * As we waited the extent range, the data_rsv_map must be empty
2846          * in the range, as written data range will be released from it.
2847          * And for prealloacted extent, it will also be released when
2848          * its metadata is written.
2849          * So this is completely used as cleanup.
2850          */
2851         btrfs_qgroup_free_data(inode, alloc_start, alloc_end - alloc_start);
2852         inode_unlock(inode);
2853         /* Let go of our reservation. */
2854         btrfs_free_reserved_data_space(inode, alloc_start,
2855                                        alloc_end - alloc_start);
2856         return ret;
2857 }
2858 
2859 static int find_desired_extent(struct inode *inode, loff_t *offset, int whence)
2860 {
2861         struct btrfs_root *root = BTRFS_I(inode)->root;
2862         struct extent_map *em = NULL;
2863         struct extent_state *cached_state = NULL;
2864         u64 lockstart;
2865         u64 lockend;
2866         u64 start;
2867         u64 len;
2868         int ret = 0;
2869 
2870         if (inode->i_size == 0)
2871                 return -ENXIO;
2872 
2873         /*
2874          * *offset can be negative, in this case we start finding DATA/HOLE from
2875          * the very start of the file.
2876          */
2877         start = max_t(loff_t, 0, *offset);
2878 
2879         lockstart = round_down(start, root->sectorsize);
2880         lockend = round_up(i_size_read(inode), root->sectorsize);
2881         if (lockend <= lockstart)
2882                 lockend = lockstart + root->sectorsize;
2883         lockend--;
2884         len = lockend - lockstart + 1;
2885 
2886         lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2887                          &cached_state);
2888 
2889         while (start < inode->i_size) {
2890                 em = btrfs_get_extent_fiemap(inode, NULL, 0, start, len, 0);
2891                 if (IS_ERR(em)) {
2892                         ret = PTR_ERR(em);
2893                         em = NULL;
2894                         break;
2895                 }
2896 
2897                 if (whence == SEEK_HOLE &&
2898                     (em->block_start == EXTENT_MAP_HOLE ||
2899                      test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
2900                         break;
2901                 else if (whence == SEEK_DATA &&
2902                            (em->block_start != EXTENT_MAP_HOLE &&
2903                             !test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
2904                         break;
2905 
2906                 start = em->start + em->len;
2907                 free_extent_map(em);
2908                 em = NULL;
2909                 cond_resched();
2910         }
2911         free_extent_map(em);
2912         if (!ret) {
2913                 if (whence == SEEK_DATA && start >= inode->i_size)
2914                         ret = -ENXIO;
2915                 else
2916                         *offset = min_t(loff_t, start, inode->i_size);
2917         }
2918         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2919                              &cached_state, GFP_NOFS);
2920         return ret;
2921 }
2922 
2923 static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
2924 {
2925         struct inode *inode = file->f_mapping->host;
2926         int ret;
2927 
2928         inode_lock(inode);
2929         switch (whence) {
2930         case SEEK_END:
2931         case SEEK_CUR:
2932                 offset = generic_file_llseek(file, offset, whence);
2933                 goto out;
2934         case SEEK_DATA:
2935         case SEEK_HOLE:
2936                 if (offset >= i_size_read(inode)) {
2937                         inode_unlock(inode);
2938                         return -ENXIO;
2939                 }
2940 
2941                 ret = find_desired_extent(inode, &offset, whence);
2942                 if (ret) {
2943                         inode_unlock(inode);
2944                         return ret;
2945                 }
2946         }
2947 
2948         offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
2949 out:
2950         inode_unlock(inode);
2951         return offset;
2952 }
2953 
2954 const struct file_operations btrfs_file_operations = {
2955         .llseek         = btrfs_file_llseek,
2956         .read_iter      = generic_file_read_iter,
2957         .splice_read    = generic_file_splice_read,
2958         .write_iter     = btrfs_file_write_iter,
2959         .mmap           = btrfs_file_mmap,
2960         .open           = generic_file_open,
2961         .release        = btrfs_release_file,
2962         .fsync          = btrfs_sync_file,
2963         .fallocate      = btrfs_fallocate,
2964         .unlocked_ioctl = btrfs_ioctl,
2965 #ifdef CONFIG_COMPAT
2966         .compat_ioctl   = btrfs_compat_ioctl,
2967 #endif
2968         .copy_file_range = btrfs_copy_file_range,
2969         .clone_file_range = btrfs_clone_file_range,
2970         .dedupe_file_range = btrfs_dedupe_file_range,
2971 };
2972 
2973 void btrfs_auto_defrag_exit(void)
2974 {
2975         kmem_cache_destroy(btrfs_inode_defrag_cachep);
2976 }
2977 
2978 int btrfs_auto_defrag_init(void)
2979 {
2980         btrfs_inode_defrag_cachep = kmem_cache_create("btrfs_inode_defrag",
2981                                         sizeof(struct inode_defrag), 0,
2982                                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
2983                                         NULL);
2984         if (!btrfs_inode_defrag_cachep)
2985                 return -ENOMEM;
2986 
2987         return 0;
2988 }
2989 
2990 int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end)
2991 {
2992         int ret;
2993 
2994         /*
2995          * So with compression we will find and lock a dirty page and clear the
2996          * first one as dirty, setup an async extent, and immediately return
2997          * with the entire range locked but with nobody actually marked with
2998          * writeback.  So we can't just filemap_write_and_wait_range() and
2999          * expect it to work since it will just kick off a thread to do the
3000          * actual work.  So we need to call filemap_fdatawrite_range _again_
3001          * since it will wait on the page lock, which won't be unlocked until
3002          * after the pages have been marked as writeback and so we're good to go
3003          * from there.  We have to do this otherwise we'll miss the ordered
3004          * extents and that results in badness.  Please Josef, do not think you
3005          * know better and pull this out at some point in the future, it is
3006          * right and you are wrong.
3007          */
3008         ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
3009         if (!ret && test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
3010                              &BTRFS_I(inode)->runtime_flags))
3011                 ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
3012 
3013         return ret;
3014 }
3015 

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