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

Version: ~ [ linux-5.4-rc7 ] ~ [ linux-5.3.11 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.84 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.154 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.201 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.201 ] ~ [ 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-3.16.77 ] ~ [ 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/compat.h>
 31 #include <linux/slab.h>
 32 #include <linux/btrfs.h>
 33 #include <linux/uio.h>
 34 #include "ctree.h"
 35 #include "disk-io.h"
 36 #include "transaction.h"
 37 #include "btrfs_inode.h"
 38 #include "print-tree.h"
 39 #include "tree-log.h"
 40 #include "locking.h"
 41 #include "volumes.h"
 42 #include "qgroup.h"
 43 #include "compression.h"
 44 
 45 static struct kmem_cache *btrfs_inode_defrag_cachep;
 46 /*
 47  * when auto defrag is enabled we
 48  * queue up these defrag structs to remember which
 49  * inodes need defragging passes
 50  */
 51 struct inode_defrag {
 52         struct rb_node rb_node;
 53         /* objectid */
 54         u64 ino;
 55         /*
 56          * transid where the defrag was added, we search for
 57          * extents newer than this
 58          */
 59         u64 transid;
 60 
 61         /* root objectid */
 62         u64 root;
 63 
 64         /* last offset we were able to defrag */
 65         u64 last_offset;
 66 
 67         /* if we've wrapped around back to zero once already */
 68         int cycled;
 69 };
 70 
 71 static int __compare_inode_defrag(struct inode_defrag *defrag1,
 72                                   struct inode_defrag *defrag2)
 73 {
 74         if (defrag1->root > defrag2->root)
 75                 return 1;
 76         else if (defrag1->root < defrag2->root)
 77                 return -1;
 78         else if (defrag1->ino > defrag2->ino)
 79                 return 1;
 80         else if (defrag1->ino < defrag2->ino)
 81                 return -1;
 82         else
 83                 return 0;
 84 }
 85 
 86 /* pop a record for an inode into the defrag tree.  The lock
 87  * must be held already
 88  *
 89  * If you're inserting a record for an older transid than an
 90  * existing record, the transid already in the tree is lowered
 91  *
 92  * If an existing record is found the defrag item you
 93  * pass in is freed
 94  */
 95 static int __btrfs_add_inode_defrag(struct inode *inode,
 96                                     struct inode_defrag *defrag)
 97 {
 98         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 99         struct inode_defrag *entry;
100         struct rb_node **p;
101         struct rb_node *parent = NULL;
102         int ret;
103 
104         p = &fs_info->defrag_inodes.rb_node;
105         while (*p) {
106                 parent = *p;
107                 entry = rb_entry(parent, struct inode_defrag, rb_node);
108 
109                 ret = __compare_inode_defrag(defrag, entry);
110                 if (ret < 0)
111                         p = &parent->rb_left;
112                 else if (ret > 0)
113                         p = &parent->rb_right;
114                 else {
115                         /* if we're reinserting an entry for
116                          * an old defrag run, make sure to
117                          * lower the transid of our existing record
118                          */
119                         if (defrag->transid < entry->transid)
120                                 entry->transid = defrag->transid;
121                         if (defrag->last_offset > entry->last_offset)
122                                 entry->last_offset = defrag->last_offset;
123                         return -EEXIST;
124                 }
125         }
126         set_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
127         rb_link_node(&defrag->rb_node, parent, p);
128         rb_insert_color(&defrag->rb_node, &fs_info->defrag_inodes);
129         return 0;
130 }
131 
132 static inline int __need_auto_defrag(struct btrfs_fs_info *fs_info)
133 {
134         if (!btrfs_test_opt(fs_info, AUTO_DEFRAG))
135                 return 0;
136 
137         if (btrfs_fs_closing(fs_info))
138                 return 0;
139 
140         return 1;
141 }
142 
143 /*
144  * insert a defrag record for this inode if auto defrag is
145  * enabled
146  */
147 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
148                            struct inode *inode)
149 {
150         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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(fs_info))
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(&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(&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_fs_info *fs_info = btrfs_sb(inode->i_sb);
201         int ret;
202 
203         if (!__need_auto_defrag(fs_info))
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(&fs_info->defrag_inodes_lock);
211         ret = __btrfs_add_inode_defrag(inode, defrag);
212         spin_unlock(&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))
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 inode *inode, struct page **pages,
489                       size_t num_pages, loff_t pos, size_t write_bytes,
490                       struct extent_state **cached)
491 {
492         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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) fs_info->sectorsize - 1);
502         num_bytes = round_up(write_bytes + pos - start_pos,
503                              fs_info->sectorsize);
504 
505         end_of_last_block = start_pos + num_bytes - 1;
506         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
507                                         cached, 0);
508         if (err)
509                 return err;
510 
511         for (i = 0; i < num_pages; i++) {
512                 struct page *p = pages[i];
513                 SetPageUptodate(p);
514                 ClearPageChecked(p);
515                 set_page_dirty(p);
516         }
517 
518         /*
519          * we've only changed i_size in ram, and we haven't updated
520          * the disk i_size.  There is no need to log the inode
521          * at this time.
522          */
523         if (end_pos > isize)
524                 i_size_write(inode, end_pos);
525         return 0;
526 }
527 
528 /*
529  * this drops all the extents in the cache that intersect the range
530  * [start, end].  Existing extents are split as required.
531  */
532 void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
533                              int skip_pinned)
534 {
535         struct extent_map *em;
536         struct extent_map *split = NULL;
537         struct extent_map *split2 = NULL;
538         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
539         u64 len = end - start + 1;
540         u64 gen;
541         int ret;
542         int testend = 1;
543         unsigned long flags;
544         int compressed = 0;
545         bool modified;
546 
547         WARN_ON(end < start);
548         if (end == (u64)-1) {
549                 len = (u64)-1;
550                 testend = 0;
551         }
552         while (1) {
553                 int no_splits = 0;
554 
555                 modified = false;
556                 if (!split)
557                         split = alloc_extent_map();
558                 if (!split2)
559                         split2 = alloc_extent_map();
560                 if (!split || !split2)
561                         no_splits = 1;
562 
563                 write_lock(&em_tree->lock);
564                 em = lookup_extent_mapping(em_tree, start, len);
565                 if (!em) {
566                         write_unlock(&em_tree->lock);
567                         break;
568                 }
569                 flags = em->flags;
570                 gen = em->generation;
571                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
572                         if (testend && em->start + em->len >= start + len) {
573                                 free_extent_map(em);
574                                 write_unlock(&em_tree->lock);
575                                 break;
576                         }
577                         start = em->start + em->len;
578                         if (testend)
579                                 len = start + len - (em->start + em->len);
580                         free_extent_map(em);
581                         write_unlock(&em_tree->lock);
582                         continue;
583                 }
584                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
585                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
586                 clear_bit(EXTENT_FLAG_LOGGING, &flags);
587                 modified = !list_empty(&em->list);
588                 if (no_splits)
589                         goto next;
590 
591                 if (em->start < start) {
592                         split->start = em->start;
593                         split->len = start - em->start;
594 
595                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
596                                 split->orig_start = em->orig_start;
597                                 split->block_start = em->block_start;
598 
599                                 if (compressed)
600                                         split->block_len = em->block_len;
601                                 else
602                                         split->block_len = split->len;
603                                 split->orig_block_len = max(split->block_len,
604                                                 em->orig_block_len);
605                                 split->ram_bytes = em->ram_bytes;
606                         } else {
607                                 split->orig_start = split->start;
608                                 split->block_len = 0;
609                                 split->block_start = em->block_start;
610                                 split->orig_block_len = 0;
611                                 split->ram_bytes = split->len;
612                         }
613 
614                         split->generation = gen;
615                         split->bdev = em->bdev;
616                         split->flags = flags;
617                         split->compress_type = em->compress_type;
618                         replace_extent_mapping(em_tree, em, split, modified);
619                         free_extent_map(split);
620                         split = split2;
621                         split2 = NULL;
622                 }
623                 if (testend && em->start + em->len > start + len) {
624                         u64 diff = start + len - em->start;
625 
626                         split->start = start + len;
627                         split->len = em->start + em->len - (start + len);
628                         split->bdev = em->bdev;
629                         split->flags = flags;
630                         split->compress_type = em->compress_type;
631                         split->generation = gen;
632 
633                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
634                                 split->orig_block_len = max(em->block_len,
635                                                     em->orig_block_len);
636 
637                                 split->ram_bytes = em->ram_bytes;
638                                 if (compressed) {
639                                         split->block_len = em->block_len;
640                                         split->block_start = em->block_start;
641                                         split->orig_start = em->orig_start;
642                                 } else {
643                                         split->block_len = split->len;
644                                         split->block_start = em->block_start
645                                                 + diff;
646                                         split->orig_start = em->orig_start;
647                                 }
648                         } else {
649                                 split->ram_bytes = split->len;
650                                 split->orig_start = split->start;
651                                 split->block_len = 0;
652                                 split->block_start = em->block_start;
653                                 split->orig_block_len = 0;
654                         }
655 
656                         if (extent_map_in_tree(em)) {
657                                 replace_extent_mapping(em_tree, em, split,
658                                                        modified);
659                         } else {
660                                 ret = add_extent_mapping(em_tree, split,
661                                                          modified);
662                                 ASSERT(ret == 0); /* Logic error */
663                         }
664                         free_extent_map(split);
665                         split = NULL;
666                 }
667 next:
668                 if (extent_map_in_tree(em))
669                         remove_extent_mapping(em_tree, em);
670                 write_unlock(&em_tree->lock);
671 
672                 /* once for us */
673                 free_extent_map(em);
674                 /* once for the tree*/
675                 free_extent_map(em);
676         }
677         if (split)
678                 free_extent_map(split);
679         if (split2)
680                 free_extent_map(split2);
681 }
682 
683 /*
684  * this is very complex, but the basic idea is to drop all extents
685  * in the range start - end.  hint_block is filled in with a block number
686  * that would be a good hint to the block allocator for this file.
687  *
688  * If an extent intersects the range but is not entirely inside the range
689  * it is either truncated or split.  Anything entirely inside the range
690  * is deleted from the tree.
691  */
692 int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
693                          struct btrfs_root *root, struct inode *inode,
694                          struct btrfs_path *path, u64 start, u64 end,
695                          u64 *drop_end, int drop_cache,
696                          int replace_extent,
697                          u32 extent_item_size,
698                          int *key_inserted)
699 {
700         struct btrfs_fs_info *fs_info = root->fs_info;
701         struct extent_buffer *leaf;
702         struct btrfs_file_extent_item *fi;
703         struct btrfs_key key;
704         struct btrfs_key new_key;
705         u64 ino = btrfs_ino(inode);
706         u64 search_start = start;
707         u64 disk_bytenr = 0;
708         u64 num_bytes = 0;
709         u64 extent_offset = 0;
710         u64 extent_end = 0;
711         u64 last_end = start;
712         int del_nr = 0;
713         int del_slot = 0;
714         int extent_type;
715         int recow;
716         int ret;
717         int modify_tree = -1;
718         int update_refs;
719         int found = 0;
720         int leafs_visited = 0;
721 
722         if (drop_cache)
723                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
724 
725         if (start >= BTRFS_I(inode)->disk_i_size && !replace_extent)
726                 modify_tree = 0;
727 
728         update_refs = (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
729                        root == fs_info->tree_root);
730         while (1) {
731                 recow = 0;
732                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
733                                                search_start, modify_tree);
734                 if (ret < 0)
735                         break;
736                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
737                         leaf = path->nodes[0];
738                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
739                         if (key.objectid == ino &&
740                             key.type == BTRFS_EXTENT_DATA_KEY)
741                                 path->slots[0]--;
742                 }
743                 ret = 0;
744                 leafs_visited++;
745 next_slot:
746                 leaf = path->nodes[0];
747                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
748                         BUG_ON(del_nr > 0);
749                         ret = btrfs_next_leaf(root, path);
750                         if (ret < 0)
751                                 break;
752                         if (ret > 0) {
753                                 ret = 0;
754                                 break;
755                         }
756                         leafs_visited++;
757                         leaf = path->nodes[0];
758                         recow = 1;
759                 }
760 
761                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
762 
763                 if (key.objectid > ino)
764                         break;
765                 if (WARN_ON_ONCE(key.objectid < ino) ||
766                     key.type < BTRFS_EXTENT_DATA_KEY) {
767                         ASSERT(del_nr == 0);
768                         path->slots[0]++;
769                         goto next_slot;
770                 }
771                 if (key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
772                         break;
773 
774                 fi = btrfs_item_ptr(leaf, path->slots[0],
775                                     struct btrfs_file_extent_item);
776                 extent_type = btrfs_file_extent_type(leaf, fi);
777 
778                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
779                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
780                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
781                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
782                         extent_offset = btrfs_file_extent_offset(leaf, fi);
783                         extent_end = key.offset +
784                                 btrfs_file_extent_num_bytes(leaf, fi);
785                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
786                         extent_end = key.offset +
787                                 btrfs_file_extent_inline_len(leaf,
788                                                      path->slots[0], fi);
789                 } else {
790                         /* can't happen */
791                         BUG();
792                 }
793 
794                 /*
795                  * Don't skip extent items representing 0 byte lengths. They
796                  * used to be created (bug) if while punching holes we hit
797                  * -ENOSPC condition. So if we find one here, just ensure we
798                  * delete it, otherwise we would insert a new file extent item
799                  * with the same key (offset) as that 0 bytes length file
800                  * extent item in the call to setup_items_for_insert() later
801                  * in this function.
802                  */
803                 if (extent_end == key.offset && extent_end >= search_start) {
804                         last_end = extent_end;
805                         goto delete_extent_item;
806                 }
807 
808                 if (extent_end <= search_start) {
809                         path->slots[0]++;
810                         goto next_slot;
811                 }
812 
813                 found = 1;
814                 search_start = max(key.offset, start);
815                 if (recow || !modify_tree) {
816                         modify_tree = -1;
817                         btrfs_release_path(path);
818                         continue;
819                 }
820 
821                 /*
822                  *     | - range to drop - |
823                  *  | -------- extent -------- |
824                  */
825                 if (start > key.offset && end < extent_end) {
826                         BUG_ON(del_nr > 0);
827                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
828                                 ret = -EOPNOTSUPP;
829                                 break;
830                         }
831 
832                         memcpy(&new_key, &key, sizeof(new_key));
833                         new_key.offset = start;
834                         ret = btrfs_duplicate_item(trans, root, path,
835                                                    &new_key);
836                         if (ret == -EAGAIN) {
837                                 btrfs_release_path(path);
838                                 continue;
839                         }
840                         if (ret < 0)
841                                 break;
842 
843                         leaf = path->nodes[0];
844                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
845                                             struct btrfs_file_extent_item);
846                         btrfs_set_file_extent_num_bytes(leaf, fi,
847                                                         start - key.offset);
848 
849                         fi = btrfs_item_ptr(leaf, path->slots[0],
850                                             struct btrfs_file_extent_item);
851 
852                         extent_offset += start - key.offset;
853                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
854                         btrfs_set_file_extent_num_bytes(leaf, fi,
855                                                         extent_end - start);
856                         btrfs_mark_buffer_dirty(leaf);
857 
858                         if (update_refs && disk_bytenr > 0) {
859                                 ret = btrfs_inc_extent_ref(trans, fs_info,
860                                                 disk_bytenr, num_bytes, 0,
861                                                 root->root_key.objectid,
862                                                 new_key.objectid,
863                                                 start - extent_offset);
864                                 BUG_ON(ret); /* -ENOMEM */
865                         }
866                         key.offset = start;
867                 }
868                 /*
869                  * From here on out we will have actually dropped something, so
870                  * last_end can be updated.
871                  */
872                 last_end = extent_end;
873 
874                 /*
875                  *  | ---- range to drop ----- |
876                  *      | -------- extent -------- |
877                  */
878                 if (start <= key.offset && end < extent_end) {
879                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
880                                 ret = -EOPNOTSUPP;
881                                 break;
882                         }
883 
884                         memcpy(&new_key, &key, sizeof(new_key));
885                         new_key.offset = end;
886                         btrfs_set_item_key_safe(fs_info, path, &new_key);
887 
888                         extent_offset += end - key.offset;
889                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
890                         btrfs_set_file_extent_num_bytes(leaf, fi,
891                                                         extent_end - end);
892                         btrfs_mark_buffer_dirty(leaf);
893                         if (update_refs && disk_bytenr > 0)
894                                 inode_sub_bytes(inode, end - key.offset);
895                         break;
896                 }
897 
898                 search_start = extent_end;
899                 /*
900                  *       | ---- range to drop ----- |
901                  *  | -------- extent -------- |
902                  */
903                 if (start > key.offset && end >= extent_end) {
904                         BUG_ON(del_nr > 0);
905                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
906                                 ret = -EOPNOTSUPP;
907                                 break;
908                         }
909 
910                         btrfs_set_file_extent_num_bytes(leaf, fi,
911                                                         start - key.offset);
912                         btrfs_mark_buffer_dirty(leaf);
913                         if (update_refs && disk_bytenr > 0)
914                                 inode_sub_bytes(inode, extent_end - start);
915                         if (end == extent_end)
916                                 break;
917 
918                         path->slots[0]++;
919                         goto next_slot;
920                 }
921 
922                 /*
923                  *  | ---- range to drop ----- |
924                  *    | ------ extent ------ |
925                  */
926                 if (start <= key.offset && end >= extent_end) {
927 delete_extent_item:
928                         if (del_nr == 0) {
929                                 del_slot = path->slots[0];
930                                 del_nr = 1;
931                         } else {
932                                 BUG_ON(del_slot + del_nr != path->slots[0]);
933                                 del_nr++;
934                         }
935 
936                         if (update_refs &&
937                             extent_type == BTRFS_FILE_EXTENT_INLINE) {
938                                 inode_sub_bytes(inode,
939                                                 extent_end - key.offset);
940                                 extent_end = ALIGN(extent_end,
941                                                    fs_info->sectorsize);
942                         } else if (update_refs && disk_bytenr > 0) {
943                                 ret = btrfs_free_extent(trans, fs_info,
944                                                 disk_bytenr, num_bytes, 0,
945                                                 root->root_key.objectid,
946                                                 key.objectid, key.offset -
947                                                 extent_offset);
948                                 BUG_ON(ret); /* -ENOMEM */
949                                 inode_sub_bytes(inode,
950                                                 extent_end - key.offset);
951                         }
952 
953                         if (end == extent_end)
954                                 break;
955 
956                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
957                                 path->slots[0]++;
958                                 goto next_slot;
959                         }
960 
961                         ret = btrfs_del_items(trans, root, path, del_slot,
962                                               del_nr);
963                         if (ret) {
964                                 btrfs_abort_transaction(trans, ret);
965                                 break;
966                         }
967 
968                         del_nr = 0;
969                         del_slot = 0;
970 
971                         btrfs_release_path(path);
972                         continue;
973                 }
974 
975                 BUG_ON(1);
976         }
977 
978         if (!ret && del_nr > 0) {
979                 /*
980                  * Set path->slots[0] to first slot, so that after the delete
981                  * if items are move off from our leaf to its immediate left or
982                  * right neighbor leafs, we end up with a correct and adjusted
983                  * path->slots[0] for our insertion (if replace_extent != 0).
984                  */
985                 path->slots[0] = del_slot;
986                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
987                 if (ret)
988                         btrfs_abort_transaction(trans, ret);
989         }
990 
991         leaf = path->nodes[0];
992         /*
993          * If btrfs_del_items() was called, it might have deleted a leaf, in
994          * which case it unlocked our path, so check path->locks[0] matches a
995          * write lock.
996          */
997         if (!ret && replace_extent && leafs_visited == 1 &&
998             (path->locks[0] == BTRFS_WRITE_LOCK_BLOCKING ||
999              path->locks[0] == BTRFS_WRITE_LOCK) &&
1000             btrfs_leaf_free_space(fs_info, leaf) >=
1001             sizeof(struct btrfs_item) + extent_item_size) {
1002 
1003                 key.objectid = ino;
1004                 key.type = BTRFS_EXTENT_DATA_KEY;
1005                 key.offset = start;
1006                 if (!del_nr && path->slots[0] < btrfs_header_nritems(leaf)) {
1007                         struct btrfs_key slot_key;
1008 
1009                         btrfs_item_key_to_cpu(leaf, &slot_key, path->slots[0]);
1010                         if (btrfs_comp_cpu_keys(&key, &slot_key) > 0)
1011                                 path->slots[0]++;
1012                 }
1013                 setup_items_for_insert(root, path, &key,
1014                                        &extent_item_size,
1015                                        extent_item_size,
1016                                        sizeof(struct btrfs_item) +
1017                                        extent_item_size, 1);
1018                 *key_inserted = 1;
1019         }
1020 
1021         if (!replace_extent || !(*key_inserted))
1022                 btrfs_release_path(path);
1023         if (drop_end)
1024                 *drop_end = found ? min(end, last_end) : end;
1025         return ret;
1026 }
1027 
1028 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
1029                        struct btrfs_root *root, struct inode *inode, u64 start,
1030                        u64 end, int drop_cache)
1031 {
1032         struct btrfs_path *path;
1033         int ret;
1034 
1035         path = btrfs_alloc_path();
1036         if (!path)
1037                 return -ENOMEM;
1038         ret = __btrfs_drop_extents(trans, root, inode, path, start, end, NULL,
1039                                    drop_cache, 0, 0, NULL);
1040         btrfs_free_path(path);
1041         return ret;
1042 }
1043 
1044 static int extent_mergeable(struct extent_buffer *leaf, int slot,
1045                             u64 objectid, u64 bytenr, u64 orig_offset,
1046                             u64 *start, u64 *end)
1047 {
1048         struct btrfs_file_extent_item *fi;
1049         struct btrfs_key key;
1050         u64 extent_end;
1051 
1052         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
1053                 return 0;
1054 
1055         btrfs_item_key_to_cpu(leaf, &key, slot);
1056         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
1057                 return 0;
1058 
1059         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1060         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
1061             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
1062             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
1063             btrfs_file_extent_compression(leaf, fi) ||
1064             btrfs_file_extent_encryption(leaf, fi) ||
1065             btrfs_file_extent_other_encoding(leaf, fi))
1066                 return 0;
1067 
1068         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1069         if ((*start && *start != key.offset) || (*end && *end != extent_end))
1070                 return 0;
1071 
1072         *start = key.offset;
1073         *end = extent_end;
1074         return 1;
1075 }
1076 
1077 /*
1078  * Mark extent in the range start - end as written.
1079  *
1080  * This changes extent type from 'pre-allocated' to 'regular'. If only
1081  * part of extent is marked as written, the extent will be split into
1082  * two or three.
1083  */
1084 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
1085                               struct inode *inode, u64 start, u64 end)
1086 {
1087         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1088         struct btrfs_root *root = BTRFS_I(inode)->root;
1089         struct extent_buffer *leaf;
1090         struct btrfs_path *path;
1091         struct btrfs_file_extent_item *fi;
1092         struct btrfs_key key;
1093         struct btrfs_key new_key;
1094         u64 bytenr;
1095         u64 num_bytes;
1096         u64 extent_end;
1097         u64 orig_offset;
1098         u64 other_start;
1099         u64 other_end;
1100         u64 split;
1101         int del_nr = 0;
1102         int del_slot = 0;
1103         int recow;
1104         int ret;
1105         u64 ino = btrfs_ino(inode);
1106 
1107         path = btrfs_alloc_path();
1108         if (!path)
1109                 return -ENOMEM;
1110 again:
1111         recow = 0;
1112         split = start;
1113         key.objectid = ino;
1114         key.type = BTRFS_EXTENT_DATA_KEY;
1115         key.offset = split;
1116 
1117         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1118         if (ret < 0)
1119                 goto out;
1120         if (ret > 0 && path->slots[0] > 0)
1121                 path->slots[0]--;
1122 
1123         leaf = path->nodes[0];
1124         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1125         if (key.objectid != ino ||
1126             key.type != BTRFS_EXTENT_DATA_KEY) {
1127                 ret = -EINVAL;
1128                 btrfs_abort_transaction(trans, ret);
1129                 goto out;
1130         }
1131         fi = btrfs_item_ptr(leaf, path->slots[0],
1132                             struct btrfs_file_extent_item);
1133         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_PREALLOC) {
1134                 ret = -EINVAL;
1135                 btrfs_abort_transaction(trans, ret);
1136                 goto out;
1137         }
1138         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1139         if (key.offset > start || extent_end < end) {
1140                 ret = -EINVAL;
1141                 btrfs_abort_transaction(trans, ret);
1142                 goto out;
1143         }
1144 
1145         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1146         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1147         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
1148         memcpy(&new_key, &key, sizeof(new_key));
1149 
1150         if (start == key.offset && end < extent_end) {
1151                 other_start = 0;
1152                 other_end = start;
1153                 if (extent_mergeable(leaf, path->slots[0] - 1,
1154                                      ino, bytenr, orig_offset,
1155                                      &other_start, &other_end)) {
1156                         new_key.offset = end;
1157                         btrfs_set_item_key_safe(fs_info, path, &new_key);
1158                         fi = btrfs_item_ptr(leaf, path->slots[0],
1159                                             struct btrfs_file_extent_item);
1160                         btrfs_set_file_extent_generation(leaf, fi,
1161                                                          trans->transid);
1162                         btrfs_set_file_extent_num_bytes(leaf, fi,
1163                                                         extent_end - end);
1164                         btrfs_set_file_extent_offset(leaf, fi,
1165                                                      end - orig_offset);
1166                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1167                                             struct btrfs_file_extent_item);
1168                         btrfs_set_file_extent_generation(leaf, fi,
1169                                                          trans->transid);
1170                         btrfs_set_file_extent_num_bytes(leaf, fi,
1171                                                         end - other_start);
1172                         btrfs_mark_buffer_dirty(leaf);
1173                         goto out;
1174                 }
1175         }
1176 
1177         if (start > key.offset && end == extent_end) {
1178                 other_start = end;
1179                 other_end = 0;
1180                 if (extent_mergeable(leaf, path->slots[0] + 1,
1181                                      ino, bytenr, orig_offset,
1182                                      &other_start, &other_end)) {
1183                         fi = btrfs_item_ptr(leaf, path->slots[0],
1184                                             struct btrfs_file_extent_item);
1185                         btrfs_set_file_extent_num_bytes(leaf, fi,
1186                                                         start - key.offset);
1187                         btrfs_set_file_extent_generation(leaf, fi,
1188                                                          trans->transid);
1189                         path->slots[0]++;
1190                         new_key.offset = start;
1191                         btrfs_set_item_key_safe(fs_info, path, &new_key);
1192 
1193                         fi = btrfs_item_ptr(leaf, path->slots[0],
1194                                             struct btrfs_file_extent_item);
1195                         btrfs_set_file_extent_generation(leaf, fi,
1196                                                          trans->transid);
1197                         btrfs_set_file_extent_num_bytes(leaf, fi,
1198                                                         other_end - start);
1199                         btrfs_set_file_extent_offset(leaf, fi,
1200                                                      start - orig_offset);
1201                         btrfs_mark_buffer_dirty(leaf);
1202                         goto out;
1203                 }
1204         }
1205 
1206         while (start > key.offset || end < extent_end) {
1207                 if (key.offset == start)
1208                         split = end;
1209 
1210                 new_key.offset = split;
1211                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
1212                 if (ret == -EAGAIN) {
1213                         btrfs_release_path(path);
1214                         goto again;
1215                 }
1216                 if (ret < 0) {
1217                         btrfs_abort_transaction(trans, ret);
1218                         goto out;
1219                 }
1220 
1221                 leaf = path->nodes[0];
1222                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1223                                     struct btrfs_file_extent_item);
1224                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1225                 btrfs_set_file_extent_num_bytes(leaf, fi,
1226                                                 split - key.offset);
1227 
1228                 fi = btrfs_item_ptr(leaf, path->slots[0],
1229                                     struct btrfs_file_extent_item);
1230 
1231                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1232                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
1233                 btrfs_set_file_extent_num_bytes(leaf, fi,
1234                                                 extent_end - split);
1235                 btrfs_mark_buffer_dirty(leaf);
1236 
1237                 ret = btrfs_inc_extent_ref(trans, fs_info, bytenr, num_bytes,
1238                                            0, root->root_key.objectid,
1239                                            ino, orig_offset);
1240                 if (ret) {
1241                         btrfs_abort_transaction(trans, ret);
1242                         goto out;
1243                 }
1244 
1245                 if (split == start) {
1246                         key.offset = start;
1247                 } else {
1248                         if (start != key.offset) {
1249                                 ret = -EINVAL;
1250                                 btrfs_abort_transaction(trans, ret);
1251                                 goto out;
1252                         }
1253                         path->slots[0]--;
1254                         extent_end = end;
1255                 }
1256                 recow = 1;
1257         }
1258 
1259         other_start = end;
1260         other_end = 0;
1261         if (extent_mergeable(leaf, path->slots[0] + 1,
1262                              ino, bytenr, orig_offset,
1263                              &other_start, &other_end)) {
1264                 if (recow) {
1265                         btrfs_release_path(path);
1266                         goto again;
1267                 }
1268                 extent_end = other_end;
1269                 del_slot = path->slots[0] + 1;
1270                 del_nr++;
1271                 ret = btrfs_free_extent(trans, fs_info, bytenr, num_bytes,
1272                                         0, root->root_key.objectid,
1273                                         ino, orig_offset);
1274                 if (ret) {
1275                         btrfs_abort_transaction(trans, ret);
1276                         goto out;
1277                 }
1278         }
1279         other_start = 0;
1280         other_end = start;
1281         if (extent_mergeable(leaf, path->slots[0] - 1,
1282                              ino, bytenr, orig_offset,
1283                              &other_start, &other_end)) {
1284                 if (recow) {
1285                         btrfs_release_path(path);
1286                         goto again;
1287                 }
1288                 key.offset = other_start;
1289                 del_slot = path->slots[0];
1290                 del_nr++;
1291                 ret = btrfs_free_extent(trans, fs_info, bytenr, num_bytes,
1292                                         0, root->root_key.objectid,
1293                                         ino, orig_offset);
1294                 if (ret) {
1295                         btrfs_abort_transaction(trans, ret);
1296                         goto out;
1297                 }
1298         }
1299         if (del_nr == 0) {
1300                 fi = btrfs_item_ptr(leaf, path->slots[0],
1301                            struct btrfs_file_extent_item);
1302                 btrfs_set_file_extent_type(leaf, fi,
1303                                            BTRFS_FILE_EXTENT_REG);
1304                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1305                 btrfs_mark_buffer_dirty(leaf);
1306         } else {
1307                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1308                            struct btrfs_file_extent_item);
1309                 btrfs_set_file_extent_type(leaf, fi,
1310                                            BTRFS_FILE_EXTENT_REG);
1311                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1312                 btrfs_set_file_extent_num_bytes(leaf, fi,
1313                                                 extent_end - key.offset);
1314                 btrfs_mark_buffer_dirty(leaf);
1315 
1316                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1317                 if (ret < 0) {
1318                         btrfs_abort_transaction(trans, ret);
1319                         goto out;
1320                 }
1321         }
1322 out:
1323         btrfs_free_path(path);
1324         return 0;
1325 }
1326 
1327 /*
1328  * on error we return an unlocked page and the error value
1329  * on success we return a locked page and 0
1330  */
1331 static int prepare_uptodate_page(struct inode *inode,
1332                                  struct page *page, u64 pos,
1333                                  bool force_uptodate)
1334 {
1335         int ret = 0;
1336 
1337         if (((pos & (PAGE_SIZE - 1)) || force_uptodate) &&
1338             !PageUptodate(page)) {
1339                 ret = btrfs_readpage(NULL, page);
1340                 if (ret)
1341                         return ret;
1342                 lock_page(page);
1343                 if (!PageUptodate(page)) {
1344                         unlock_page(page);
1345                         return -EIO;
1346                 }
1347                 if (page->mapping != inode->i_mapping) {
1348                         unlock_page(page);
1349                         return -EAGAIN;
1350                 }
1351         }
1352         return 0;
1353 }
1354 
1355 /*
1356  * this just gets pages into the page cache and locks them down.
1357  */
1358 static noinline int prepare_pages(struct inode *inode, struct page **pages,
1359                                   size_t num_pages, loff_t pos,
1360                                   size_t write_bytes, bool force_uptodate)
1361 {
1362         int i;
1363         unsigned long index = pos >> PAGE_SHIFT;
1364         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1365         int err = 0;
1366         int faili;
1367 
1368         for (i = 0; i < num_pages; i++) {
1369 again:
1370                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1371                                                mask | __GFP_WRITE);
1372                 if (!pages[i]) {
1373                         faili = i - 1;
1374                         err = -ENOMEM;
1375                         goto fail;
1376                 }
1377 
1378                 if (i == 0)
1379                         err = prepare_uptodate_page(inode, pages[i], pos,
1380                                                     force_uptodate);
1381                 if (!err && i == num_pages - 1)
1382                         err = prepare_uptodate_page(inode, pages[i],
1383                                                     pos + write_bytes, false);
1384                 if (err) {
1385                         put_page(pages[i]);
1386                         if (err == -EAGAIN) {
1387                                 err = 0;
1388                                 goto again;
1389                         }
1390                         faili = i - 1;
1391                         goto fail;
1392                 }
1393                 wait_on_page_writeback(pages[i]);
1394         }
1395 
1396         return 0;
1397 fail:
1398         while (faili >= 0) {
1399                 unlock_page(pages[faili]);
1400                 put_page(pages[faili]);
1401                 faili--;
1402         }
1403         return err;
1404 
1405 }
1406 
1407 /*
1408  * This function locks the extent and properly waits for data=ordered extents
1409  * to finish before allowing the pages to be modified if need.
1410  *
1411  * The return value:
1412  * 1 - the extent is locked
1413  * 0 - the extent is not locked, and everything is OK
1414  * -EAGAIN - need re-prepare the pages
1415  * the other < 0 number - Something wrong happens
1416  */
1417 static noinline int
1418 lock_and_cleanup_extent_if_need(struct inode *inode, struct page **pages,
1419                                 size_t num_pages, loff_t pos,
1420                                 size_t write_bytes,
1421                                 u64 *lockstart, u64 *lockend,
1422                                 struct extent_state **cached_state)
1423 {
1424         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1425         u64 start_pos;
1426         u64 last_pos;
1427         int i;
1428         int ret = 0;
1429 
1430         start_pos = round_down(pos, fs_info->sectorsize);
1431         last_pos = start_pos
1432                 + round_up(pos + write_bytes - start_pos,
1433                            fs_info->sectorsize) - 1;
1434 
1435         if (start_pos < inode->i_size) {
1436                 struct btrfs_ordered_extent *ordered;
1437                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
1438                                  start_pos, last_pos, cached_state);
1439                 ordered = btrfs_lookup_ordered_range(inode, start_pos,
1440                                                      last_pos - start_pos + 1);
1441                 if (ordered &&
1442                     ordered->file_offset + ordered->len > start_pos &&
1443                     ordered->file_offset <= last_pos) {
1444                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1445                                              start_pos, last_pos,
1446                                              cached_state, GFP_NOFS);
1447                         for (i = 0; i < num_pages; i++) {
1448                                 unlock_page(pages[i]);
1449                                 put_page(pages[i]);
1450                         }
1451                         btrfs_start_ordered_extent(inode, ordered, 1);
1452                         btrfs_put_ordered_extent(ordered);
1453                         return -EAGAIN;
1454                 }
1455                 if (ordered)
1456                         btrfs_put_ordered_extent(ordered);
1457 
1458                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1459                                   last_pos, EXTENT_DIRTY | EXTENT_DELALLOC |
1460                                   EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
1461                                   0, 0, cached_state, GFP_NOFS);
1462                 *lockstart = start_pos;
1463                 *lockend = last_pos;
1464                 ret = 1;
1465         }
1466 
1467         for (i = 0; i < num_pages; i++) {
1468                 if (clear_page_dirty_for_io(pages[i]))
1469                         account_page_redirty(pages[i]);
1470                 set_page_extent_mapped(pages[i]);
1471                 WARN_ON(!PageLocked(pages[i]));
1472         }
1473 
1474         return ret;
1475 }
1476 
1477 static noinline int check_can_nocow(struct inode *inode, loff_t pos,
1478                                     size_t *write_bytes)
1479 {
1480         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1481         struct btrfs_root *root = BTRFS_I(inode)->root;
1482         struct btrfs_ordered_extent *ordered;
1483         u64 lockstart, lockend;
1484         u64 num_bytes;
1485         int ret;
1486 
1487         ret = btrfs_start_write_no_snapshoting(root);
1488         if (!ret)
1489                 return -ENOSPC;
1490 
1491         lockstart = round_down(pos, fs_info->sectorsize);
1492         lockend = round_up(pos + *write_bytes,
1493                            fs_info->sectorsize) - 1;
1494 
1495         while (1) {
1496                 lock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1497                 ordered = btrfs_lookup_ordered_range(inode, lockstart,
1498                                                      lockend - lockstart + 1);
1499                 if (!ordered) {
1500                         break;
1501                 }
1502                 unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1503                 btrfs_start_ordered_extent(inode, ordered, 1);
1504                 btrfs_put_ordered_extent(ordered);
1505         }
1506 
1507         num_bytes = lockend - lockstart + 1;
1508         ret = can_nocow_extent(inode, lockstart, &num_bytes, NULL, NULL, NULL);
1509         if (ret <= 0) {
1510                 ret = 0;
1511                 btrfs_end_write_no_snapshoting(root);
1512         } else {
1513                 *write_bytes = min_t(size_t, *write_bytes ,
1514                                      num_bytes - pos + lockstart);
1515         }
1516 
1517         unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1518 
1519         return ret;
1520 }
1521 
1522 static noinline ssize_t __btrfs_buffered_write(struct file *file,
1523                                                struct iov_iter *i,
1524                                                loff_t pos)
1525 {
1526         struct inode *inode = file_inode(file);
1527         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1528         struct btrfs_root *root = BTRFS_I(inode)->root;
1529         struct page **pages = NULL;
1530         struct extent_state *cached_state = NULL;
1531         u64 release_bytes = 0;
1532         u64 lockstart;
1533         u64 lockend;
1534         size_t num_written = 0;
1535         int nrptrs;
1536         int ret = 0;
1537         bool only_release_metadata = false;
1538         bool force_page_uptodate = false;
1539         bool need_unlock;
1540 
1541         nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE),
1542                         PAGE_SIZE / (sizeof(struct page *)));
1543         nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1544         nrptrs = max(nrptrs, 8);
1545         pages = kmalloc_array(nrptrs, sizeof(struct page *), GFP_KERNEL);
1546         if (!pages)
1547                 return -ENOMEM;
1548 
1549         while (iov_iter_count(i) > 0) {
1550                 size_t offset = pos & (PAGE_SIZE - 1);
1551                 size_t sector_offset;
1552                 size_t write_bytes = min(iov_iter_count(i),
1553                                          nrptrs * (size_t)PAGE_SIZE -
1554                                          offset);
1555                 size_t num_pages = DIV_ROUND_UP(write_bytes + offset,
1556                                                 PAGE_SIZE);
1557                 size_t reserve_bytes;
1558                 size_t dirty_pages;
1559                 size_t copied;
1560                 size_t dirty_sectors;
1561                 size_t num_sectors;
1562 
1563                 WARN_ON(num_pages > nrptrs);
1564 
1565                 /*
1566                  * Fault pages before locking them in prepare_pages
1567                  * to avoid recursive lock
1568                  */
1569                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1570                         ret = -EFAULT;
1571                         break;
1572                 }
1573 
1574                 sector_offset = pos & (fs_info->sectorsize - 1);
1575                 reserve_bytes = round_up(write_bytes + sector_offset,
1576                                 fs_info->sectorsize);
1577 
1578                 ret = btrfs_check_data_free_space(inode, pos, write_bytes);
1579                 if (ret < 0) {
1580                         if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
1581                                                       BTRFS_INODE_PREALLOC)) &&
1582                             check_can_nocow(inode, pos, &write_bytes) > 0) {
1583                                 /*
1584                                  * For nodata cow case, no need to reserve
1585                                  * data space.
1586                                  */
1587                                 only_release_metadata = true;
1588                                 /*
1589                                  * our prealloc extent may be smaller than
1590                                  * write_bytes, so scale down.
1591                                  */
1592                                 num_pages = DIV_ROUND_UP(write_bytes + offset,
1593                                                          PAGE_SIZE);
1594                                 reserve_bytes = round_up(write_bytes +
1595                                                          sector_offset,
1596                                                          fs_info->sectorsize);
1597                         } else {
1598                                 break;
1599                         }
1600                 }
1601 
1602                 ret = btrfs_delalloc_reserve_metadata(inode, reserve_bytes);
1603                 if (ret) {
1604                         if (!only_release_metadata)
1605                                 btrfs_free_reserved_data_space(inode, pos,
1606                                                                write_bytes);
1607                         else
1608                                 btrfs_end_write_no_snapshoting(root);
1609                         break;
1610                 }
1611 
1612                 release_bytes = reserve_bytes;
1613                 need_unlock = false;
1614 again:
1615                 /*
1616                  * This is going to setup the pages array with the number of
1617                  * pages we want, so we don't really need to worry about the
1618                  * contents of pages from loop to loop
1619                  */
1620                 ret = prepare_pages(inode, pages, num_pages,
1621                                     pos, write_bytes,
1622                                     force_page_uptodate);
1623                 if (ret)
1624                         break;
1625 
1626                 ret = lock_and_cleanup_extent_if_need(inode, pages, num_pages,
1627                                                 pos, write_bytes, &lockstart,
1628                                                 &lockend, &cached_state);
1629                 if (ret < 0) {
1630                         if (ret == -EAGAIN)
1631                                 goto again;
1632                         break;
1633                 } else if (ret > 0) {
1634                         need_unlock = true;
1635                         ret = 0;
1636                 }
1637 
1638                 copied = btrfs_copy_from_user(pos, write_bytes, pages, i);
1639 
1640                 num_sectors = BTRFS_BYTES_TO_BLKS(fs_info, reserve_bytes);
1641                 dirty_sectors = round_up(copied + sector_offset,
1642                                         fs_info->sectorsize);
1643                 dirty_sectors = BTRFS_BYTES_TO_BLKS(fs_info, dirty_sectors);
1644 
1645                 /*
1646                  * if we have trouble faulting in the pages, fall
1647                  * back to one page at a time
1648                  */
1649                 if (copied < write_bytes)
1650                         nrptrs = 1;
1651 
1652                 if (copied == 0) {
1653                         force_page_uptodate = true;
1654                         dirty_sectors = 0;
1655                         dirty_pages = 0;
1656                 } else {
1657                         force_page_uptodate = false;
1658                         dirty_pages = DIV_ROUND_UP(copied + offset,
1659                                                    PAGE_SIZE);
1660                 }
1661 
1662                 /*
1663                  * If we had a short copy we need to release the excess delaloc
1664                  * bytes we reserved.  We need to increment outstanding_extents
1665                  * because btrfs_delalloc_release_space and
1666                  * btrfs_delalloc_release_metadata will decrement it, but
1667                  * we still have an outstanding extent for the chunk we actually
1668                  * managed to copy.
1669                  */
1670                 if (num_sectors > dirty_sectors) {
1671                         /* release everything except the sectors we dirtied */
1672                         release_bytes -= dirty_sectors <<
1673                                                 fs_info->sb->s_blocksize_bits;
1674                         if (copied > 0) {
1675                                 spin_lock(&BTRFS_I(inode)->lock);
1676                                 BTRFS_I(inode)->outstanding_extents++;
1677                                 spin_unlock(&BTRFS_I(inode)->lock);
1678                         }
1679                         if (only_release_metadata) {
1680                                 btrfs_delalloc_release_metadata(inode,
1681                                                                 release_bytes);
1682                         } else {
1683                                 u64 __pos;
1684 
1685                                 __pos = round_down(pos,
1686                                                    fs_info->sectorsize) +
1687                                         (dirty_pages << PAGE_SHIFT);
1688                                 btrfs_delalloc_release_space(inode, __pos,
1689                                                              release_bytes);
1690                         }
1691                 }
1692 
1693                 release_bytes = round_up(copied + sector_offset,
1694                                         fs_info->sectorsize);
1695 
1696                 if (copied > 0)
1697                         ret = btrfs_dirty_pages(inode, pages, dirty_pages,
1698                                                 pos, copied, NULL);
1699                 if (need_unlock)
1700                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1701                                              lockstart, lockend, &cached_state,
1702                                              GFP_NOFS);
1703                 if (ret) {
1704                         btrfs_drop_pages(pages, num_pages);
1705                         break;
1706                 }
1707 
1708                 release_bytes = 0;
1709                 if (only_release_metadata)
1710                         btrfs_end_write_no_snapshoting(root);
1711 
1712                 if (only_release_metadata && copied > 0) {
1713                         lockstart = round_down(pos,
1714                                                fs_info->sectorsize);
1715                         lockend = round_up(pos + copied,
1716                                            fs_info->sectorsize) - 1;
1717 
1718                         set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
1719                                        lockend, EXTENT_NORESERVE, NULL,
1720                                        NULL, GFP_NOFS);
1721                         only_release_metadata = false;
1722                 }
1723 
1724                 btrfs_drop_pages(pages, num_pages);
1725 
1726                 cond_resched();
1727 
1728                 balance_dirty_pages_ratelimited(inode->i_mapping);
1729                 if (dirty_pages < (fs_info->nodesize >> PAGE_SHIFT) + 1)
1730                         btrfs_btree_balance_dirty(fs_info);
1731 
1732                 pos += copied;
1733                 num_written += copied;
1734         }
1735 
1736         kfree(pages);
1737 
1738         if (release_bytes) {
1739                 if (only_release_metadata) {
1740                         btrfs_end_write_no_snapshoting(root);
1741                         btrfs_delalloc_release_metadata(inode, release_bytes);
1742                 } else {
1743                         btrfs_delalloc_release_space(inode,
1744                                                 round_down(pos, fs_info->sectorsize),
1745                                                 release_bytes);
1746                 }
1747         }
1748 
1749         return num_written ? num_written : ret;
1750 }
1751 
1752 static ssize_t __btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
1753 {
1754         struct file *file = iocb->ki_filp;
1755         struct inode *inode = file_inode(file);
1756         loff_t pos = iocb->ki_pos;
1757         ssize_t written;
1758         ssize_t written_buffered;
1759         loff_t endbyte;
1760         int err;
1761 
1762         written = generic_file_direct_write(iocb, from);
1763 
1764         if (written < 0 || !iov_iter_count(from))
1765                 return written;
1766 
1767         pos += written;
1768         written_buffered = __btrfs_buffered_write(file, from, pos);
1769         if (written_buffered < 0) {
1770                 err = written_buffered;
1771                 goto out;
1772         }
1773         /*
1774          * Ensure all data is persisted. We want the next direct IO read to be
1775          * able to read what was just written.
1776          */
1777         endbyte = pos + written_buffered - 1;
1778         err = btrfs_fdatawrite_range(inode, pos, endbyte);
1779         if (err)
1780                 goto out;
1781         err = filemap_fdatawait_range(inode->i_mapping, pos, endbyte);
1782         if (err)
1783                 goto out;
1784         written += written_buffered;
1785         iocb->ki_pos = pos + written_buffered;
1786         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_SHIFT,
1787                                  endbyte >> PAGE_SHIFT);
1788 out:
1789         return written ? written : err;
1790 }
1791 
1792 static void update_time_for_write(struct inode *inode)
1793 {
1794         struct timespec now;
1795 
1796         if (IS_NOCMTIME(inode))
1797                 return;
1798 
1799         now = current_time(inode);
1800         if (!timespec_equal(&inode->i_mtime, &now))
1801                 inode->i_mtime = now;
1802 
1803         if (!timespec_equal(&inode->i_ctime, &now))
1804                 inode->i_ctime = now;
1805 
1806         if (IS_I_VERSION(inode))
1807                 inode_inc_iversion(inode);
1808 }
1809 
1810 static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
1811                                     struct iov_iter *from)
1812 {
1813         struct file *file = iocb->ki_filp;
1814         struct inode *inode = file_inode(file);
1815         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1816         struct btrfs_root *root = BTRFS_I(inode)->root;
1817         u64 start_pos;
1818         u64 end_pos;
1819         ssize_t num_written = 0;
1820         bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
1821         ssize_t err;
1822         loff_t pos;
1823         size_t count;
1824         loff_t oldsize;
1825         int clean_page = 0;
1826 
1827         inode_lock(inode);
1828         err = generic_write_checks(iocb, from);
1829         if (err <= 0) {
1830                 inode_unlock(inode);
1831                 return err;
1832         }
1833 
1834         current->backing_dev_info = inode_to_bdi(inode);
1835         err = file_remove_privs(file);
1836         if (err) {
1837                 inode_unlock(inode);
1838                 goto out;
1839         }
1840 
1841         /*
1842          * If BTRFS flips readonly due to some impossible error
1843          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1844          * although we have opened a file as writable, we have
1845          * to stop this write operation to ensure FS consistency.
1846          */
1847         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
1848                 inode_unlock(inode);
1849                 err = -EROFS;
1850                 goto out;
1851         }
1852 
1853         /*
1854          * We reserve space for updating the inode when we reserve space for the
1855          * extent we are going to write, so we will enospc out there.  We don't
1856          * need to start yet another transaction to update the inode as we will
1857          * update the inode when we finish writing whatever data we write.
1858          */
1859         update_time_for_write(inode);
1860 
1861         pos = iocb->ki_pos;
1862         count = iov_iter_count(from);
1863         start_pos = round_down(pos, fs_info->sectorsize);
1864         oldsize = i_size_read(inode);
1865         if (start_pos > oldsize) {
1866                 /* Expand hole size to cover write data, preventing empty gap */
1867                 end_pos = round_up(pos + count,
1868                                    fs_info->sectorsize);
1869                 err = btrfs_cont_expand(inode, oldsize, end_pos);
1870                 if (err) {
1871                         inode_unlock(inode);
1872                         goto out;
1873                 }
1874                 if (start_pos > round_up(oldsize, fs_info->sectorsize))
1875                         clean_page = 1;
1876         }
1877 
1878         if (sync)
1879                 atomic_inc(&BTRFS_I(inode)->sync_writers);
1880 
1881         if (iocb->ki_flags & IOCB_DIRECT) {
1882                 num_written = __btrfs_direct_write(iocb, from);
1883         } else {
1884                 num_written = __btrfs_buffered_write(file, from, pos);
1885                 if (num_written > 0)
1886                         iocb->ki_pos = pos + num_written;
1887                 if (clean_page)
1888                         pagecache_isize_extended(inode, oldsize,
1889                                                 i_size_read(inode));
1890         }
1891 
1892         inode_unlock(inode);
1893 
1894         /*
1895          * We also have to set last_sub_trans to the current log transid,
1896          * otherwise subsequent syncs to a file that's been synced in this
1897          * transaction will appear to have already occurred.
1898          */
1899         spin_lock(&BTRFS_I(inode)->lock);
1900         BTRFS_I(inode)->last_sub_trans = root->log_transid;
1901         spin_unlock(&BTRFS_I(inode)->lock);
1902         if (num_written > 0)
1903                 num_written = generic_write_sync(iocb, num_written);
1904 
1905         if (sync)
1906                 atomic_dec(&BTRFS_I(inode)->sync_writers);
1907 out:
1908         current->backing_dev_info = NULL;
1909         return num_written ? num_written : err;
1910 }
1911 
1912 int btrfs_release_file(struct inode *inode, struct file *filp)
1913 {
1914         if (filp->private_data)
1915                 btrfs_ioctl_trans_end(filp);
1916         /*
1917          * ordered_data_close is set by settattr when we are about to truncate
1918          * a file from a non-zero size to a zero size.  This tries to
1919          * flush down new bytes that may have been written if the
1920          * application were using truncate to replace a file in place.
1921          */
1922         if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
1923                                &BTRFS_I(inode)->runtime_flags))
1924                         filemap_flush(inode->i_mapping);
1925         return 0;
1926 }
1927 
1928 static int start_ordered_ops(struct inode *inode, loff_t start, loff_t end)
1929 {
1930         int ret;
1931 
1932         atomic_inc(&BTRFS_I(inode)->sync_writers);
1933         ret = btrfs_fdatawrite_range(inode, start, end);
1934         atomic_dec(&BTRFS_I(inode)->sync_writers);
1935 
1936         return ret;
1937 }
1938 
1939 /*
1940  * fsync call for both files and directories.  This logs the inode into
1941  * the tree log instead of forcing full commits whenever possible.
1942  *
1943  * It needs to call filemap_fdatawait so that all ordered extent updates are
1944  * in the metadata btree are up to date for copying to the log.
1945  *
1946  * It drops the inode mutex before doing the tree log commit.  This is an
1947  * important optimization for directories because holding the mutex prevents
1948  * new operations on the dir while we write to disk.
1949  */
1950 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
1951 {
1952         struct dentry *dentry = file_dentry(file);
1953         struct inode *inode = d_inode(dentry);
1954         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1955         struct btrfs_root *root = BTRFS_I(inode)->root;
1956         struct btrfs_trans_handle *trans;
1957         struct btrfs_log_ctx ctx;
1958         int ret = 0;
1959         bool full_sync = 0;
1960         u64 len;
1961 
1962         /*
1963          * The range length can be represented by u64, we have to do the typecasts
1964          * to avoid signed overflow if it's [0, LLONG_MAX] eg. from fsync()
1965          */
1966         len = (u64)end - (u64)start + 1;
1967         trace_btrfs_sync_file(file, datasync);
1968 
1969         /*
1970          * We write the dirty pages in the range and wait until they complete
1971          * out of the ->i_mutex. If so, we can flush the dirty pages by
1972          * multi-task, and make the performance up.  See
1973          * btrfs_wait_ordered_range for an explanation of the ASYNC check.
1974          */
1975         ret = start_ordered_ops(inode, start, end);
1976         if (ret)
1977                 return ret;
1978 
1979         inode_lock(inode);
1980         atomic_inc(&root->log_batch);
1981         full_sync = test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
1982                              &BTRFS_I(inode)->runtime_flags);
1983         /*
1984          * We might have have had more pages made dirty after calling
1985          * start_ordered_ops and before acquiring the inode's i_mutex.
1986          */
1987         if (full_sync) {
1988                 /*
1989                  * For a full sync, we need to make sure any ordered operations
1990                  * start and finish before we start logging the inode, so that
1991                  * all extents are persisted and the respective file extent
1992                  * items are in the fs/subvol btree.
1993                  */
1994                 ret = btrfs_wait_ordered_range(inode, start, len);
1995         } else {
1996                 /*
1997                  * Start any new ordered operations before starting to log the
1998                  * inode. We will wait for them to finish in btrfs_sync_log().
1999                  *
2000                  * Right before acquiring the inode's mutex, we might have new
2001                  * writes dirtying pages, which won't immediately start the
2002                  * respective ordered operations - that is done through the
2003                  * fill_delalloc callbacks invoked from the writepage and
2004                  * writepages address space operations. So make sure we start
2005                  * all ordered operations before starting to log our inode. Not
2006                  * doing this means that while logging the inode, writeback
2007                  * could start and invoke writepage/writepages, which would call
2008                  * the fill_delalloc callbacks (cow_file_range,
2009                  * submit_compressed_extents). These callbacks add first an
2010                  * extent map to the modified list of extents and then create
2011                  * the respective ordered operation, which means in
2012                  * tree-log.c:btrfs_log_inode() we might capture all existing
2013                  * ordered operations (with btrfs_get_logged_extents()) before
2014                  * the fill_delalloc callback adds its ordered operation, and by
2015                  * the time we visit the modified list of extent maps (with
2016                  * btrfs_log_changed_extents()), we see and process the extent
2017                  * map they created. We then use the extent map to construct a
2018                  * file extent item for logging without waiting for the
2019                  * respective ordered operation to finish - this file extent
2020                  * item points to a disk location that might not have yet been
2021                  * written to, containing random data - so after a crash a log
2022                  * replay will make our inode have file extent items that point
2023                  * to disk locations containing invalid data, as we returned
2024                  * success to userspace without waiting for the respective
2025                  * ordered operation to finish, because it wasn't captured by
2026                  * btrfs_get_logged_extents().
2027                  */
2028                 ret = start_ordered_ops(inode, start, end);
2029         }
2030         if (ret) {
2031                 inode_unlock(inode);
2032                 goto out;
2033         }
2034         atomic_inc(&root->log_batch);
2035 
2036         /*
2037          * If the last transaction that changed this file was before the current
2038          * transaction and we have the full sync flag set in our inode, we can
2039          * bail out now without any syncing.
2040          *
2041          * Note that we can't bail out if the full sync flag isn't set. This is
2042          * because when the full sync flag is set we start all ordered extents
2043          * and wait for them to fully complete - when they complete they update
2044          * the inode's last_trans field through:
2045          *
2046          *     btrfs_finish_ordered_io() ->
2047          *         btrfs_update_inode_fallback() ->
2048          *             btrfs_update_inode() ->
2049          *                 btrfs_set_inode_last_trans()
2050          *
2051          * So we are sure that last_trans is up to date and can do this check to
2052          * bail out safely. For the fast path, when the full sync flag is not
2053          * set in our inode, we can not do it because we start only our ordered
2054          * extents and don't wait for them to complete (that is when
2055          * btrfs_finish_ordered_io runs), so here at this point their last_trans
2056          * value might be less than or equals to fs_info->last_trans_committed,
2057          * and setting a speculative last_trans for an inode when a buffered
2058          * write is made (such as fs_info->generation + 1 for example) would not
2059          * be reliable since after setting the value and before fsync is called
2060          * any number of transactions can start and commit (transaction kthread
2061          * commits the current transaction periodically), and a transaction
2062          * commit does not start nor waits for ordered extents to complete.
2063          */
2064         smp_mb();
2065         if (btrfs_inode_in_log(inode, fs_info->generation) ||
2066             (full_sync && BTRFS_I(inode)->last_trans <=
2067              fs_info->last_trans_committed) ||
2068             (!btrfs_have_ordered_extents_in_range(inode, start, len) &&
2069              BTRFS_I(inode)->last_trans
2070              <= fs_info->last_trans_committed)) {
2071                 /*
2072                  * We've had everything committed since the last time we were
2073                  * modified so clear this flag in case it was set for whatever
2074                  * reason, it's no longer relevant.
2075                  */
2076                 clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2077                           &BTRFS_I(inode)->runtime_flags);
2078                 /*
2079                  * An ordered extent might have started before and completed
2080                  * already with io errors, in which case the inode was not
2081                  * updated and we end up here. So check the inode's mapping
2082                  * flags for any errors that might have happened while doing
2083                  * writeback of file data.
2084                  */
2085                 ret = filemap_check_errors(inode->i_mapping);
2086                 inode_unlock(inode);
2087                 goto out;
2088         }
2089 
2090         /*
2091          * ok we haven't committed the transaction yet, lets do a commit
2092          */
2093         if (file->private_data)
2094                 btrfs_ioctl_trans_end(file);
2095 
2096         /*
2097          * We use start here because we will need to wait on the IO to complete
2098          * in btrfs_sync_log, which could require joining a transaction (for
2099          * example checking cross references in the nocow path).  If we use join
2100          * here we could get into a situation where we're waiting on IO to
2101          * happen that is blocked on a transaction trying to commit.  With start
2102          * we inc the extwriter counter, so we wait for all extwriters to exit
2103          * before we start blocking join'ers.  This comment is to keep somebody
2104          * from thinking they are super smart and changing this to
2105          * btrfs_join_transaction *cough*Josef*cough*.
2106          */
2107         trans = btrfs_start_transaction(root, 0);
2108         if (IS_ERR(trans)) {
2109                 ret = PTR_ERR(trans);
2110                 inode_unlock(inode);
2111                 goto out;
2112         }
2113         trans->sync = true;
2114 
2115         btrfs_init_log_ctx(&ctx, inode);
2116 
2117         ret = btrfs_log_dentry_safe(trans, root, dentry, start, end, &ctx);
2118         if (ret < 0) {
2119                 /* Fallthrough and commit/free transaction. */
2120                 ret = 1;
2121         }
2122 
2123         /* we've logged all the items and now have a consistent
2124          * version of the file in the log.  It is possible that
2125          * someone will come in and modify the file, but that's
2126          * fine because the log is consistent on disk, and we
2127          * have references to all of the file's extents
2128          *
2129          * It is possible that someone will come in and log the
2130          * file again, but that will end up using the synchronization
2131          * inside btrfs_sync_log to keep things safe.
2132          */
2133         inode_unlock(inode);
2134 
2135         /*
2136          * If any of the ordered extents had an error, just return it to user
2137          * space, so that the application knows some writes didn't succeed and
2138          * can take proper action (retry for e.g.). Blindly committing the
2139          * transaction in this case, would fool userspace that everything was
2140          * successful. And we also want to make sure our log doesn't contain
2141          * file extent items pointing to extents that weren't fully written to -
2142          * just like in the non fast fsync path, where we check for the ordered
2143          * operation's error flag before writing to the log tree and return -EIO
2144          * if any of them had this flag set (btrfs_wait_ordered_range) -
2145          * therefore we need to check for errors in the ordered operations,
2146          * which are indicated by ctx.io_err.
2147          */
2148         if (ctx.io_err) {
2149                 btrfs_end_transaction(trans);
2150                 ret = ctx.io_err;
2151                 goto out;
2152         }
2153 
2154         if (ret != BTRFS_NO_LOG_SYNC) {
2155                 if (!ret) {
2156                         ret = btrfs_sync_log(trans, root, &ctx);
2157                         if (!ret) {
2158                                 ret = btrfs_end_transaction(trans);
2159                                 goto out;
2160                         }
2161                 }
2162                 if (!full_sync) {
2163                         ret = btrfs_wait_ordered_range(inode, start, len);
2164                         if (ret) {
2165                                 btrfs_end_transaction(trans);
2166                                 goto out;
2167                         }
2168                 }
2169                 ret = btrfs_commit_transaction(trans);
2170         } else {
2171                 ret = btrfs_end_transaction(trans);
2172         }
2173 out:
2174         return ret > 0 ? -EIO : ret;
2175 }
2176 
2177 static const struct vm_operations_struct btrfs_file_vm_ops = {
2178         .fault          = filemap_fault,
2179         .map_pages      = filemap_map_pages,
2180         .page_mkwrite   = btrfs_page_mkwrite,
2181 };
2182 
2183 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
2184 {
2185         struct address_space *mapping = filp->f_mapping;
2186 
2187         if (!mapping->a_ops->readpage)
2188                 return -ENOEXEC;
2189 
2190         file_accessed(filp);
2191         vma->vm_ops = &btrfs_file_vm_ops;
2192 
2193         return 0;
2194 }
2195 
2196 static int hole_mergeable(struct inode *inode, struct extent_buffer *leaf,
2197                           int slot, u64 start, u64 end)
2198 {
2199         struct btrfs_file_extent_item *fi;
2200         struct btrfs_key key;
2201 
2202         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
2203                 return 0;
2204 
2205         btrfs_item_key_to_cpu(leaf, &key, slot);
2206         if (key.objectid != btrfs_ino(inode) ||
2207             key.type != BTRFS_EXTENT_DATA_KEY)
2208                 return 0;
2209 
2210         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
2211 
2212         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
2213                 return 0;
2214 
2215         if (btrfs_file_extent_disk_bytenr(leaf, fi))
2216                 return 0;
2217 
2218         if (key.offset == end)
2219                 return 1;
2220         if (key.offset + btrfs_file_extent_num_bytes(leaf, fi) == start)
2221                 return 1;
2222         return 0;
2223 }
2224 
2225 static int fill_holes(struct btrfs_trans_handle *trans, struct inode *inode,
2226                       struct btrfs_path *path, u64 offset, u64 end)
2227 {
2228         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2229         struct btrfs_root *root = BTRFS_I(inode)->root;
2230         struct extent_buffer *leaf;
2231         struct btrfs_file_extent_item *fi;
2232         struct extent_map *hole_em;
2233         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2234         struct btrfs_key key;
2235         int ret;
2236 
2237         if (btrfs_fs_incompat(fs_info, NO_HOLES))
2238                 goto out;
2239 
2240         key.objectid = btrfs_ino(inode);
2241         key.type = BTRFS_EXTENT_DATA_KEY;
2242         key.offset = offset;
2243 
2244         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
2245         if (ret <= 0) {
2246                 /*
2247                  * We should have dropped this offset, so if we find it then
2248                  * something has gone horribly wrong.
2249                  */
2250                 if (ret == 0)
2251                         ret = -EINVAL;
2252                 return ret;
2253         }
2254 
2255         leaf = path->nodes[0];
2256         if (hole_mergeable(inode, leaf, path->slots[0]-1, offset, end)) {
2257                 u64 num_bytes;
2258 
2259                 path->slots[0]--;
2260                 fi = btrfs_item_ptr(leaf, path->slots[0],
2261                                     struct btrfs_file_extent_item);
2262                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) +
2263                         end - offset;
2264                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2265                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2266                 btrfs_set_file_extent_offset(leaf, fi, 0);
2267                 btrfs_mark_buffer_dirty(leaf);
2268                 goto out;
2269         }
2270 
2271         if (hole_mergeable(inode, leaf, path->slots[0], offset, end)) {
2272                 u64 num_bytes;
2273 
2274                 key.offset = offset;
2275                 btrfs_set_item_key_safe(fs_info, path, &key);
2276                 fi = btrfs_item_ptr(leaf, path->slots[0],
2277                                     struct btrfs_file_extent_item);
2278                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + end -
2279                         offset;
2280                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2281                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2282                 btrfs_set_file_extent_offset(leaf, fi, 0);
2283                 btrfs_mark_buffer_dirty(leaf);
2284                 goto out;
2285         }
2286         btrfs_release_path(path);
2287 
2288         ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode), offset,
2289                                        0, 0, end - offset, 0, end - offset,
2290                                        0, 0, 0);
2291         if (ret)
2292                 return ret;
2293 
2294 out:
2295         btrfs_release_path(path);
2296 
2297         hole_em = alloc_extent_map();
2298         if (!hole_em) {
2299                 btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2300                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2301                         &BTRFS_I(inode)->runtime_flags);
2302         } else {
2303                 hole_em->start = offset;
2304                 hole_em->len = end - offset;
2305                 hole_em->ram_bytes = hole_em->len;
2306                 hole_em->orig_start = offset;
2307 
2308                 hole_em->block_start = EXTENT_MAP_HOLE;
2309                 hole_em->block_len = 0;
2310                 hole_em->orig_block_len = 0;
2311                 hole_em->bdev = fs_info->fs_devices->latest_bdev;
2312                 hole_em->compress_type = BTRFS_COMPRESS_NONE;
2313                 hole_em->generation = trans->transid;
2314 
2315                 do {
2316                         btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2317                         write_lock(&em_tree->lock);
2318                         ret = add_extent_mapping(em_tree, hole_em, 1);
2319                         write_unlock(&em_tree->lock);
2320                 } while (ret == -EEXIST);
2321                 free_extent_map(hole_em);
2322                 if (ret)
2323                         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2324                                 &BTRFS_I(inode)->runtime_flags);
2325         }
2326 
2327         return 0;
2328 }
2329 
2330 /*
2331  * Find a hole extent on given inode and change start/len to the end of hole
2332  * extent.(hole/vacuum extent whose em->start <= start &&
2333  *         em->start + em->len > start)
2334  * When a hole extent is found, return 1 and modify start/len.
2335  */
2336 static int find_first_non_hole(struct inode *inode, u64 *start, u64 *len)
2337 {
2338         struct extent_map *em;
2339         int ret = 0;
2340 
2341         em = btrfs_get_extent(inode, NULL, 0, *start, *len, 0);
2342         if (IS_ERR_OR_NULL(em)) {
2343                 if (!em)
2344                         ret = -ENOMEM;
2345                 else
2346                         ret = PTR_ERR(em);
2347                 return ret;
2348         }
2349 
2350         /* Hole or vacuum extent(only exists in no-hole mode) */
2351         if (em->block_start == EXTENT_MAP_HOLE) {
2352                 ret = 1;
2353                 *len = em->start + em->len > *start + *len ?
2354                        0 : *start + *len - em->start - em->len;
2355                 *start = em->start + em->len;
2356         }
2357         free_extent_map(em);
2358         return ret;
2359 }
2360 
2361 static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
2362 {
2363         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2364         struct btrfs_root *root = BTRFS_I(inode)->root;
2365         struct extent_state *cached_state = NULL;
2366         struct btrfs_path *path;
2367         struct btrfs_block_rsv *rsv;
2368         struct btrfs_trans_handle *trans;
2369         u64 lockstart;
2370         u64 lockend;
2371         u64 tail_start;
2372         u64 tail_len;
2373         u64 orig_start = offset;
2374         u64 cur_offset;
2375         u64 min_size = btrfs_calc_trans_metadata_size(fs_info, 1);
2376         u64 drop_end;
2377         int ret = 0;
2378         int err = 0;
2379         unsigned int rsv_count;
2380         bool same_block;
2381         bool no_holes = btrfs_fs_incompat(fs_info, NO_HOLES);
2382         u64 ino_size;
2383         bool truncated_block = false;
2384         bool updated_inode = false;
2385 
2386         ret = btrfs_wait_ordered_range(inode, offset, len);
2387         if (ret)
2388                 return ret;
2389 
2390         inode_lock(inode);
2391         ino_size = round_up(inode->i_size, fs_info->sectorsize);
2392         ret = find_first_non_hole(inode, &offset, &len);
2393         if (ret < 0)
2394                 goto out_only_mutex;
2395         if (ret && !len) {
2396                 /* Already in a large hole */
2397                 ret = 0;
2398                 goto out_only_mutex;
2399         }
2400 
2401         lockstart = round_up(offset, btrfs_inode_sectorsize(inode));
2402         lockend = round_down(offset + len,
2403                              btrfs_inode_sectorsize(inode)) - 1;
2404         same_block = (BTRFS_BYTES_TO_BLKS(fs_info, offset))
2405                 == (BTRFS_BYTES_TO_BLKS(fs_info, offset + len - 1));
2406         /*
2407          * We needn't truncate any block which is beyond the end of the file
2408          * because we are sure there is no data there.
2409          */
2410         /*
2411          * Only do this if we are in the same block and we aren't doing the
2412          * entire block.
2413          */
2414         if (same_block && len < fs_info->sectorsize) {
2415                 if (offset < ino_size) {
2416                         truncated_block = true;
2417                         ret = btrfs_truncate_block(inode, offset, len, 0);
2418                 } else {
2419                         ret = 0;
2420                 }
2421                 goto out_only_mutex;
2422         }
2423 
2424         /* zero back part of the first block */
2425         if (offset < ino_size) {
2426                 truncated_block = true;
2427                 ret = btrfs_truncate_block(inode, offset, 0, 0);
2428                 if (ret) {
2429                         inode_unlock(inode);
2430                         return ret;
2431                 }
2432         }
2433 
2434         /* Check the aligned pages after the first unaligned page,
2435          * if offset != orig_start, which means the first unaligned page
2436          * including several following pages are already in holes,
2437          * the extra check can be skipped */
2438         if (offset == orig_start) {
2439                 /* after truncate page, check hole again */
2440                 len = offset + len - lockstart;
2441                 offset = lockstart;
2442                 ret = find_first_non_hole(inode, &offset, &len);
2443                 if (ret < 0)
2444                         goto out_only_mutex;
2445                 if (ret && !len) {
2446                         ret = 0;
2447                         goto out_only_mutex;
2448                 }
2449                 lockstart = offset;
2450         }
2451 
2452         /* Check the tail unaligned part is in a hole */
2453         tail_start = lockend + 1;
2454         tail_len = offset + len - tail_start;
2455         if (tail_len) {
2456                 ret = find_first_non_hole(inode, &tail_start, &tail_len);
2457                 if (unlikely(ret < 0))
2458                         goto out_only_mutex;
2459                 if (!ret) {
2460                         /* zero the front end of the last page */
2461                         if (tail_start + tail_len < ino_size) {
2462                                 truncated_block = true;
2463                                 ret = btrfs_truncate_block(inode,
2464                                                         tail_start + tail_len,
2465                                                         0, 1);
2466                                 if (ret)
2467                                         goto out_only_mutex;
2468                         }
2469                 }
2470         }
2471 
2472         if (lockend < lockstart) {
2473                 ret = 0;
2474                 goto out_only_mutex;
2475         }
2476 
2477         while (1) {
2478                 struct btrfs_ordered_extent *ordered;
2479 
2480                 truncate_pagecache_range(inode, lockstart, lockend);
2481 
2482                 lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2483                                  &cached_state);
2484                 ordered = btrfs_lookup_first_ordered_extent(inode, lockend);
2485 
2486                 /*
2487                  * We need to make sure we have no ordered extents in this range
2488                  * and nobody raced in and read a page in this range, if we did
2489                  * we need to try again.
2490                  */
2491                 if ((!ordered ||
2492                     (ordered->file_offset + ordered->len <= lockstart ||
2493                      ordered->file_offset > lockend)) &&
2494                      !btrfs_page_exists_in_range(inode, lockstart, lockend)) {
2495                         if (ordered)
2496                                 btrfs_put_ordered_extent(ordered);
2497                         break;
2498                 }
2499                 if (ordered)
2500                         btrfs_put_ordered_extent(ordered);
2501                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
2502                                      lockend, &cached_state, GFP_NOFS);
2503                 ret = btrfs_wait_ordered_range(inode, lockstart,
2504                                                lockend - lockstart + 1);
2505                 if (ret) {
2506                         inode_unlock(inode);
2507                         return ret;
2508                 }
2509         }
2510 
2511         path = btrfs_alloc_path();
2512         if (!path) {
2513                 ret = -ENOMEM;
2514                 goto out;
2515         }
2516 
2517         rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
2518         if (!rsv) {
2519                 ret = -ENOMEM;
2520                 goto out_free;
2521         }
2522         rsv->size = btrfs_calc_trans_metadata_size(fs_info, 1);
2523         rsv->failfast = 1;
2524 
2525         /*
2526          * 1 - update the inode
2527          * 1 - removing the extents in the range
2528          * 1 - adding the hole extent if no_holes isn't set
2529          */
2530         rsv_count = no_holes ? 2 : 3;
2531         trans = btrfs_start_transaction(root, rsv_count);
2532         if (IS_ERR(trans)) {
2533                 err = PTR_ERR(trans);
2534                 goto out_free;
2535         }
2536 
2537         ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
2538                                       min_size, 0);
2539         BUG_ON(ret);
2540         trans->block_rsv = rsv;
2541 
2542         cur_offset = lockstart;
2543         len = lockend - cur_offset;
2544         while (cur_offset < lockend) {
2545                 ret = __btrfs_drop_extents(trans, root, inode, path,
2546                                            cur_offset, lockend + 1,
2547                                            &drop_end, 1, 0, 0, NULL);
2548                 if (ret != -ENOSPC)
2549                         break;
2550 
2551                 trans->block_rsv = &fs_info->trans_block_rsv;
2552 
2553                 if (cur_offset < drop_end && cur_offset < ino_size) {
2554                         ret = fill_holes(trans, inode, path, cur_offset,
2555                                          drop_end);
2556                         if (ret) {
2557                                 /*
2558                                  * If we failed then we didn't insert our hole
2559                                  * entries for the area we dropped, so now the
2560                                  * fs is corrupted, so we must abort the
2561                                  * transaction.
2562                                  */
2563                                 btrfs_abort_transaction(trans, ret);
2564                                 err = ret;
2565                                 break;
2566                         }
2567                 }
2568 
2569                 cur_offset = drop_end;
2570 
2571                 ret = btrfs_update_inode(trans, root, inode);
2572                 if (ret) {
2573                         err = ret;
2574                         break;
2575                 }
2576 
2577                 btrfs_end_transaction(trans);
2578                 btrfs_btree_balance_dirty(fs_info);
2579 
2580                 trans = btrfs_start_transaction(root, rsv_count);
2581                 if (IS_ERR(trans)) {
2582                         ret = PTR_ERR(trans);
2583                         trans = NULL;
2584                         break;
2585                 }
2586 
2587                 ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
2588                                               rsv, min_size, 0);
2589                 BUG_ON(ret);    /* shouldn't happen */
2590                 trans->block_rsv = rsv;
2591 
2592                 ret = find_first_non_hole(inode, &cur_offset, &len);
2593                 if (unlikely(ret < 0))
2594                         break;
2595                 if (ret && !len) {
2596                         ret = 0;
2597                         break;
2598                 }
2599         }
2600 
2601         if (ret) {
2602                 err = ret;
2603                 goto out_trans;
2604         }
2605 
2606         trans->block_rsv = &fs_info->trans_block_rsv;
2607         /*
2608          * If we are using the NO_HOLES feature we might have had already an
2609          * hole that overlaps a part of the region [lockstart, lockend] and
2610          * ends at (or beyond) lockend. Since we have no file extent items to
2611          * represent holes, drop_end can be less than lockend and so we must
2612          * make sure we have an extent map representing the existing hole (the
2613          * call to __btrfs_drop_extents() might have dropped the existing extent
2614          * map representing the existing hole), otherwise the fast fsync path
2615          * will not record the existence of the hole region
2616          * [existing_hole_start, lockend].
2617          */
2618         if (drop_end <= lockend)
2619                 drop_end = lockend + 1;
2620         /*
2621          * Don't insert file hole extent item if it's for a range beyond eof
2622          * (because it's useless) or if it represents a 0 bytes range (when
2623          * cur_offset == drop_end).
2624          */
2625         if (cur_offset < ino_size && cur_offset < drop_end) {
2626                 ret = fill_holes(trans, inode, path, cur_offset, drop_end);
2627                 if (ret) {
2628                         /* Same comment as above. */
2629                         btrfs_abort_transaction(trans, ret);
2630                         err = ret;
2631                         goto out_trans;
2632                 }
2633         }
2634 
2635 out_trans:
2636         if (!trans)
2637                 goto out_free;
2638 
2639         inode_inc_iversion(inode);
2640         inode->i_mtime = inode->i_ctime = current_time(inode);
2641 
2642         trans->block_rsv = &fs_info->trans_block_rsv;
2643         ret = btrfs_update_inode(trans, root, inode);
2644         updated_inode = true;
2645         btrfs_end_transaction(trans);
2646         btrfs_btree_balance_dirty(fs_info);
2647 out_free:
2648         btrfs_free_path(path);
2649         btrfs_free_block_rsv(fs_info, rsv);
2650 out:
2651         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2652                              &cached_state, GFP_NOFS);
2653 out_only_mutex:
2654         if (!updated_inode && truncated_block && !ret && !err) {
2655                 /*
2656                  * If we only end up zeroing part of a page, we still need to
2657                  * update the inode item, so that all the time fields are
2658                  * updated as well as the necessary btrfs inode in memory fields
2659                  * for detecting, at fsync time, if the inode isn't yet in the
2660                  * log tree or it's there but not up to date.
2661                  */
2662                 trans = btrfs_start_transaction(root, 1);
2663                 if (IS_ERR(trans)) {
2664                         err = PTR_ERR(trans);
2665                 } else {
2666                         err = btrfs_update_inode(trans, root, inode);
2667                         ret = btrfs_end_transaction(trans);
2668                 }
2669         }
2670         inode_unlock(inode);
2671         if (ret && !err)
2672                 err = ret;
2673         return err;
2674 }
2675 
2676 /* Helper structure to record which range is already reserved */
2677 struct falloc_range {
2678         struct list_head list;
2679         u64 start;
2680         u64 len;
2681 };
2682 
2683 /*
2684  * Helper function to add falloc range
2685  *
2686  * Caller should have locked the larger range of extent containing
2687  * [start, len)
2688  */
2689 static int add_falloc_range(struct list_head *head, u64 start, u64 len)
2690 {
2691         struct falloc_range *prev = NULL;
2692         struct falloc_range *range = NULL;
2693 
2694         if (list_empty(head))
2695                 goto insert;
2696 
2697         /*
2698          * As fallocate iterate by bytenr order, we only need to check
2699          * the last range.
2700          */
2701         prev = list_entry(head->prev, struct falloc_range, list);
2702         if (prev->start + prev->len == start) {
2703                 prev->len += len;
2704                 return 0;
2705         }
2706 insert:
2707         range = kmalloc(sizeof(*range), GFP_KERNEL);
2708         if (!range)
2709                 return -ENOMEM;
2710         range->start = start;
2711         range->len = len;
2712         list_add_tail(&range->list, head);
2713         return 0;
2714 }
2715 
2716 static long btrfs_fallocate(struct file *file, int mode,
2717                             loff_t offset, loff_t len)
2718 {
2719         struct inode *inode = file_inode(file);
2720         struct extent_state *cached_state = NULL;
2721         struct falloc_range *range;
2722         struct falloc_range *tmp;
2723         struct list_head reserve_list;
2724         u64 cur_offset;
2725         u64 last_byte;
2726         u64 alloc_start;
2727         u64 alloc_end;
2728         u64 alloc_hint = 0;
2729         u64 locked_end;
2730         u64 actual_end = 0;
2731         struct extent_map *em;
2732         int blocksize = btrfs_inode_sectorsize(inode);
2733         int ret;
2734 
2735         alloc_start = round_down(offset, blocksize);
2736         alloc_end = round_up(offset + len, blocksize);
2737         cur_offset = alloc_start;
2738 
2739         /* Make sure we aren't being give some crap mode */
2740         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2741                 return -EOPNOTSUPP;
2742 
2743         if (mode & FALLOC_FL_PUNCH_HOLE)
2744                 return btrfs_punch_hole(inode, offset, len);
2745 
2746         /*
2747          * Only trigger disk allocation, don't trigger qgroup reserve
2748          *
2749          * For qgroup space, it will be checked later.
2750          */
2751         ret = btrfs_alloc_data_chunk_ondemand(inode, alloc_end - alloc_start);
2752         if (ret < 0)
2753                 return ret;
2754 
2755         inode_lock(inode);
2756 
2757         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) {
2758                 ret = inode_newsize_ok(inode, offset + len);
2759                 if (ret)
2760                         goto out;
2761         }
2762 
2763         /*
2764          * TODO: Move these two operations after we have checked
2765          * accurate reserved space, or fallocate can still fail but
2766          * with page truncated or size expanded.
2767          *
2768          * But that's a minor problem and won't do much harm BTW.
2769          */
2770         if (alloc_start > inode->i_size) {
2771                 ret = btrfs_cont_expand(inode, i_size_read(inode),
2772                                         alloc_start);
2773                 if (ret)
2774                         goto out;
2775         } else if (offset + len > inode->i_size) {
2776                 /*
2777                  * If we are fallocating from the end of the file onward we
2778                  * need to zero out the end of the block if i_size lands in the
2779                  * middle of a block.
2780                  */
2781                 ret = btrfs_truncate_block(inode, inode->i_size, 0, 0);
2782                 if (ret)
2783                         goto out;
2784         }
2785 
2786         /*
2787          * wait for ordered IO before we have any locks.  We'll loop again
2788          * below with the locks held.
2789          */
2790         ret = btrfs_wait_ordered_range(inode, alloc_start,
2791                                        alloc_end - alloc_start);
2792         if (ret)
2793                 goto out;
2794 
2795         locked_end = alloc_end - 1;
2796         while (1) {
2797                 struct btrfs_ordered_extent *ordered;
2798 
2799                 /* the extent lock is ordered inside the running
2800                  * transaction
2801                  */
2802                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
2803                                  locked_end, &cached_state);
2804                 ordered = btrfs_lookup_first_ordered_extent(inode,
2805                                                             alloc_end - 1);
2806                 if (ordered &&
2807                     ordered->file_offset + ordered->len > alloc_start &&
2808                     ordered->file_offset < alloc_end) {
2809                         btrfs_put_ordered_extent(ordered);
2810                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
2811                                              alloc_start, locked_end,
2812                                              &cached_state, GFP_KERNEL);
2813                         /*
2814                          * we can't wait on the range with the transaction
2815                          * running or with the extent lock held
2816                          */
2817                         ret = btrfs_wait_ordered_range(inode, alloc_start,
2818                                                        alloc_end - alloc_start);
2819                         if (ret)
2820                                 goto out;
2821                 } else {
2822                         if (ordered)
2823                                 btrfs_put_ordered_extent(ordered);
2824                         break;
2825                 }
2826         }
2827 
2828         /* First, check if we exceed the qgroup limit */
2829         INIT_LIST_HEAD(&reserve_list);
2830         while (1) {
2831                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
2832                                       alloc_end - cur_offset, 0);
2833                 if (IS_ERR_OR_NULL(em)) {
2834                         if (!em)
2835                                 ret = -ENOMEM;
2836                         else
2837                                 ret = PTR_ERR(em);
2838                         break;
2839                 }
2840                 last_byte = min(extent_map_end(em), alloc_end);
2841                 actual_end = min_t(u64, extent_map_end(em), offset + len);
2842                 last_byte = ALIGN(last_byte, blocksize);
2843                 if (em->block_start == EXTENT_MAP_HOLE ||
2844                     (cur_offset >= inode->i_size &&
2845                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
2846                         ret = add_falloc_range(&reserve_list, cur_offset,
2847                                                last_byte - cur_offset);
2848                         if (ret < 0) {
2849                                 free_extent_map(em);
2850                                 break;
2851                         }
2852                         ret = btrfs_qgroup_reserve_data(inode, cur_offset,
2853                                         last_byte - cur_offset);
2854                         if (ret < 0)
2855                                 break;
2856                 } else {
2857                         /*
2858                          * Do not need to reserve unwritten extent for this
2859                          * range, free reserved data space first, otherwise
2860                          * it'll result in false ENOSPC error.
2861                          */
2862                         btrfs_free_reserved_data_space(inode, cur_offset,
2863                                 last_byte - cur_offset);
2864                 }
2865                 free_extent_map(em);
2866                 cur_offset = last_byte;
2867                 if (cur_offset >= alloc_end)
2868                         break;
2869         }
2870 
2871         /*
2872          * If ret is still 0, means we're OK to fallocate.
2873          * Or just cleanup the list and exit.
2874          */
2875         list_for_each_entry_safe(range, tmp, &reserve_list, list) {
2876                 if (!ret)
2877                         ret = btrfs_prealloc_file_range(inode, mode,
2878                                         range->start,
2879                                         range->len, 1 << inode->i_blkbits,
2880                                         offset + len, &alloc_hint);
2881                 else
2882                         btrfs_free_reserved_data_space(inode, range->start,
2883                                                        range->len);
2884                 list_del(&range->list);
2885                 kfree(range);
2886         }
2887         if (ret < 0)
2888                 goto out_unlock;
2889 
2890         if (actual_end > inode->i_size &&
2891             !(mode & FALLOC_FL_KEEP_SIZE)) {
2892                 struct btrfs_trans_handle *trans;
2893                 struct btrfs_root *root = BTRFS_I(inode)->root;
2894 
2895                 /*
2896                  * We didn't need to allocate any more space, but we
2897                  * still extended the size of the file so we need to
2898                  * update i_size and the inode item.
2899                  */
2900                 trans = btrfs_start_transaction(root, 1);
2901                 if (IS_ERR(trans)) {
2902                         ret = PTR_ERR(trans);
2903                 } else {
2904                         inode->i_ctime = current_time(inode);
2905                         i_size_write(inode, actual_end);
2906                         btrfs_ordered_update_i_size(inode, actual_end, NULL);
2907                         ret = btrfs_update_inode(trans, root, inode);
2908                         if (ret)
2909                                 btrfs_end_transaction(trans);
2910                         else
2911                                 ret = btrfs_end_transaction(trans);
2912                 }
2913         }
2914 out_unlock:
2915         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
2916                              &cached_state, GFP_KERNEL);
2917 out:
2918         inode_unlock(inode);
2919         /* Let go of our reservation. */
2920         if (ret != 0)
2921                 btrfs_free_reserved_data_space(inode, alloc_start,
2922                                        alloc_end - cur_offset);
2923         return ret;
2924 }
2925 
2926 static int find_desired_extent(struct inode *inode, loff_t *offset, int whence)
2927 {
2928         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2929         struct extent_map *em = NULL;
2930         struct extent_state *cached_state = NULL;
2931         u64 lockstart;
2932         u64 lockend;
2933         u64 start;
2934         u64 len;
2935         int ret = 0;
2936 
2937         if (inode->i_size == 0)
2938                 return -ENXIO;
2939 
2940         /*
2941          * *offset can be negative, in this case we start finding DATA/HOLE from
2942          * the very start of the file.
2943          */
2944         start = max_t(loff_t, 0, *offset);
2945 
2946         lockstart = round_down(start, fs_info->sectorsize);
2947         lockend = round_up(i_size_read(inode),
2948                            fs_info->sectorsize);
2949         if (lockend <= lockstart)
2950                 lockend = lockstart + fs_info->sectorsize;
2951         lockend--;
2952         len = lockend - lockstart + 1;
2953 
2954         lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2955                          &cached_state);
2956 
2957         while (start < inode->i_size) {
2958                 em = btrfs_get_extent_fiemap(inode, NULL, 0, start, len, 0);
2959                 if (IS_ERR(em)) {
2960                         ret = PTR_ERR(em);
2961                         em = NULL;
2962                         break;
2963                 }
2964 
2965                 if (whence == SEEK_HOLE &&
2966                     (em->block_start == EXTENT_MAP_HOLE ||
2967                      test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
2968                         break;
2969                 else if (whence == SEEK_DATA &&
2970                            (em->block_start != EXTENT_MAP_HOLE &&
2971                             !test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
2972                         break;
2973 
2974                 start = em->start + em->len;
2975                 free_extent_map(em);
2976                 em = NULL;
2977                 cond_resched();
2978         }
2979         free_extent_map(em);
2980         if (!ret) {
2981                 if (whence == SEEK_DATA && start >= inode->i_size)
2982                         ret = -ENXIO;
2983                 else
2984                         *offset = min_t(loff_t, start, inode->i_size);
2985         }
2986         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2987                              &cached_state, GFP_NOFS);
2988         return ret;
2989 }
2990 
2991 static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
2992 {
2993         struct inode *inode = file->f_mapping->host;
2994         int ret;
2995 
2996         inode_lock(inode);
2997         switch (whence) {
2998         case SEEK_END:
2999         case SEEK_CUR:
3000                 offset = generic_file_llseek(file, offset, whence);
3001                 goto out;
3002         case SEEK_DATA:
3003         case SEEK_HOLE:
3004                 if (offset >= i_size_read(inode)) {
3005                         inode_unlock(inode);
3006                         return -ENXIO;
3007                 }
3008 
3009                 ret = find_desired_extent(inode, &offset, whence);
3010                 if (ret) {
3011                         inode_unlock(inode);
3012                         return ret;
3013                 }
3014         }
3015 
3016         offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
3017 out:
3018         inode_unlock(inode);
3019         return offset;
3020 }
3021 
3022 const struct file_operations btrfs_file_operations = {
3023         .llseek         = btrfs_file_llseek,
3024         .read_iter      = generic_file_read_iter,
3025         .splice_read    = generic_file_splice_read,
3026         .write_iter     = btrfs_file_write_iter,
3027         .mmap           = btrfs_file_mmap,
3028         .open           = generic_file_open,
3029         .release        = btrfs_release_file,
3030         .fsync          = btrfs_sync_file,
3031         .fallocate      = btrfs_fallocate,
3032         .unlocked_ioctl = btrfs_ioctl,
3033 #ifdef CONFIG_COMPAT
3034         .compat_ioctl   = btrfs_compat_ioctl,
3035 #endif
3036         .clone_file_range = btrfs_clone_file_range,
3037         .dedupe_file_range = btrfs_dedupe_file_range,
3038 };
3039 
3040 void btrfs_auto_defrag_exit(void)
3041 {
3042         kmem_cache_destroy(btrfs_inode_defrag_cachep);
3043 }
3044 
3045 int btrfs_auto_defrag_init(void)
3046 {
3047         btrfs_inode_defrag_cachep = kmem_cache_create("btrfs_inode_defrag",
3048                                         sizeof(struct inode_defrag), 0,
3049                                         SLAB_MEM_SPREAD,
3050                                         NULL);
3051         if (!btrfs_inode_defrag_cachep)
3052                 return -ENOMEM;
3053 
3054         return 0;
3055 }
3056 
3057 int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end)
3058 {
3059         int ret;
3060 
3061         /*
3062          * So with compression we will find and lock a dirty page and clear the
3063          * first one as dirty, setup an async extent, and immediately return
3064          * with the entire range locked but with nobody actually marked with
3065          * writeback.  So we can't just filemap_write_and_wait_range() and
3066          * expect it to work since it will just kick off a thread to do the
3067          * actual work.  So we need to call filemap_fdatawrite_range _again_
3068          * since it will wait on the page lock, which won't be unlocked until
3069          * after the pages have been marked as writeback and so we're good to go
3070          * from there.  We have to do this otherwise we'll miss the ordered
3071          * extents and that results in badness.  Please Josef, do not think you
3072          * know better and pull this out at some point in the future, it is
3073          * right and you are wrong.
3074          */
3075         ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
3076         if (!ret && test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
3077                              &BTRFS_I(inode)->runtime_flags))
3078                 ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
3079 
3080         return ret;
3081 }
3082 

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