5370152ea7e3affd8b587c99d3a70049b7a4c779
[sfrench/cifs-2.6.git] / fs / btrfs / file.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2007 Oracle.  All rights reserved.
4  */
5
6 #include <linux/fs.h>
7 #include <linux/pagemap.h>
8 #include <linux/time.h>
9 #include <linux/init.h>
10 #include <linux/string.h>
11 #include <linux/backing-dev.h>
12 #include <linux/falloc.h>
13 #include <linux/writeback.h>
14 #include <linux/compat.h>
15 #include <linux/slab.h>
16 #include <linux/btrfs.h>
17 #include <linux/uio.h>
18 #include <linux/iversion.h>
19 #include "ctree.h"
20 #include "disk-io.h"
21 #include "transaction.h"
22 #include "btrfs_inode.h"
23 #include "print-tree.h"
24 #include "tree-log.h"
25 #include "locking.h"
26 #include "volumes.h"
27 #include "qgroup.h"
28 #include "compression.h"
29
30 static struct kmem_cache *btrfs_inode_defrag_cachep;
31 /*
32  * when auto defrag is enabled we
33  * queue up these defrag structs to remember which
34  * inodes need defragging passes
35  */
36 struct inode_defrag {
37         struct rb_node rb_node;
38         /* objectid */
39         u64 ino;
40         /*
41          * transid where the defrag was added, we search for
42          * extents newer than this
43          */
44         u64 transid;
45
46         /* root objectid */
47         u64 root;
48
49         /* last offset we were able to defrag */
50         u64 last_offset;
51
52         /* if we've wrapped around back to zero once already */
53         int cycled;
54 };
55
56 static int __compare_inode_defrag(struct inode_defrag *defrag1,
57                                   struct inode_defrag *defrag2)
58 {
59         if (defrag1->root > defrag2->root)
60                 return 1;
61         else if (defrag1->root < defrag2->root)
62                 return -1;
63         else if (defrag1->ino > defrag2->ino)
64                 return 1;
65         else if (defrag1->ino < defrag2->ino)
66                 return -1;
67         else
68                 return 0;
69 }
70
71 /* pop a record for an inode into the defrag tree.  The lock
72  * must be held already
73  *
74  * If you're inserting a record for an older transid than an
75  * existing record, the transid already in the tree is lowered
76  *
77  * If an existing record is found the defrag item you
78  * pass in is freed
79  */
80 static int __btrfs_add_inode_defrag(struct btrfs_inode *inode,
81                                     struct inode_defrag *defrag)
82 {
83         struct btrfs_fs_info *fs_info = inode->root->fs_info;
84         struct inode_defrag *entry;
85         struct rb_node **p;
86         struct rb_node *parent = NULL;
87         int ret;
88
89         p = &fs_info->defrag_inodes.rb_node;
90         while (*p) {
91                 parent = *p;
92                 entry = rb_entry(parent, struct inode_defrag, rb_node);
93
94                 ret = __compare_inode_defrag(defrag, entry);
95                 if (ret < 0)
96                         p = &parent->rb_left;
97                 else if (ret > 0)
98                         p = &parent->rb_right;
99                 else {
100                         /* if we're reinserting an entry for
101                          * an old defrag run, make sure to
102                          * lower the transid of our existing record
103                          */
104                         if (defrag->transid < entry->transid)
105                                 entry->transid = defrag->transid;
106                         if (defrag->last_offset > entry->last_offset)
107                                 entry->last_offset = defrag->last_offset;
108                         return -EEXIST;
109                 }
110         }
111         set_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags);
112         rb_link_node(&defrag->rb_node, parent, p);
113         rb_insert_color(&defrag->rb_node, &fs_info->defrag_inodes);
114         return 0;
115 }
116
117 static inline int __need_auto_defrag(struct btrfs_fs_info *fs_info)
118 {
119         if (!btrfs_test_opt(fs_info, AUTO_DEFRAG))
120                 return 0;
121
122         if (btrfs_fs_closing(fs_info))
123                 return 0;
124
125         return 1;
126 }
127
128 /*
129  * insert a defrag record for this inode if auto defrag is
130  * enabled
131  */
132 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
133                            struct btrfs_inode *inode)
134 {
135         struct btrfs_root *root = inode->root;
136         struct btrfs_fs_info *fs_info = root->fs_info;
137         struct inode_defrag *defrag;
138         u64 transid;
139         int ret;
140
141         if (!__need_auto_defrag(fs_info))
142                 return 0;
143
144         if (test_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags))
145                 return 0;
146
147         if (trans)
148                 transid = trans->transid;
149         else
150                 transid = inode->root->last_trans;
151
152         defrag = kmem_cache_zalloc(btrfs_inode_defrag_cachep, GFP_NOFS);
153         if (!defrag)
154                 return -ENOMEM;
155
156         defrag->ino = btrfs_ino(inode);
157         defrag->transid = transid;
158         defrag->root = root->root_key.objectid;
159
160         spin_lock(&fs_info->defrag_inodes_lock);
161         if (!test_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags)) {
162                 /*
163                  * If we set IN_DEFRAG flag and evict the inode from memory,
164                  * and then re-read this inode, this new inode doesn't have
165                  * IN_DEFRAG flag. At the case, we may find the existed defrag.
166                  */
167                 ret = __btrfs_add_inode_defrag(inode, defrag);
168                 if (ret)
169                         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
170         } else {
171                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
172         }
173         spin_unlock(&fs_info->defrag_inodes_lock);
174         return 0;
175 }
176
177 /*
178  * Requeue the defrag object. If there is a defrag object that points to
179  * the same inode in the tree, we will merge them together (by
180  * __btrfs_add_inode_defrag()) and free the one that we want to requeue.
181  */
182 static void btrfs_requeue_inode_defrag(struct btrfs_inode *inode,
183                                        struct inode_defrag *defrag)
184 {
185         struct btrfs_fs_info *fs_info = inode->root->fs_info;
186         int ret;
187
188         if (!__need_auto_defrag(fs_info))
189                 goto out;
190
191         /*
192          * Here we don't check the IN_DEFRAG flag, because we need merge
193          * them together.
194          */
195         spin_lock(&fs_info->defrag_inodes_lock);
196         ret = __btrfs_add_inode_defrag(inode, defrag);
197         spin_unlock(&fs_info->defrag_inodes_lock);
198         if (ret)
199                 goto out;
200         return;
201 out:
202         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
203 }
204
205 /*
206  * pick the defragable inode that we want, if it doesn't exist, we will get
207  * the next one.
208  */
209 static struct inode_defrag *
210 btrfs_pick_defrag_inode(struct btrfs_fs_info *fs_info, u64 root, u64 ino)
211 {
212         struct inode_defrag *entry = NULL;
213         struct inode_defrag tmp;
214         struct rb_node *p;
215         struct rb_node *parent = NULL;
216         int ret;
217
218         tmp.ino = ino;
219         tmp.root = root;
220
221         spin_lock(&fs_info->defrag_inodes_lock);
222         p = fs_info->defrag_inodes.rb_node;
223         while (p) {
224                 parent = p;
225                 entry = rb_entry(parent, struct inode_defrag, rb_node);
226
227                 ret = __compare_inode_defrag(&tmp, entry);
228                 if (ret < 0)
229                         p = parent->rb_left;
230                 else if (ret > 0)
231                         p = parent->rb_right;
232                 else
233                         goto out;
234         }
235
236         if (parent && __compare_inode_defrag(&tmp, entry) > 0) {
237                 parent = rb_next(parent);
238                 if (parent)
239                         entry = rb_entry(parent, struct inode_defrag, rb_node);
240                 else
241                         entry = NULL;
242         }
243 out:
244         if (entry)
245                 rb_erase(parent, &fs_info->defrag_inodes);
246         spin_unlock(&fs_info->defrag_inodes_lock);
247         return entry;
248 }
249
250 void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info)
251 {
252         struct inode_defrag *defrag;
253         struct rb_node *node;
254
255         spin_lock(&fs_info->defrag_inodes_lock);
256         node = rb_first(&fs_info->defrag_inodes);
257         while (node) {
258                 rb_erase(node, &fs_info->defrag_inodes);
259                 defrag = rb_entry(node, struct inode_defrag, rb_node);
260                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
261
262                 cond_resched_lock(&fs_info->defrag_inodes_lock);
263
264                 node = rb_first(&fs_info->defrag_inodes);
265         }
266         spin_unlock(&fs_info->defrag_inodes_lock);
267 }
268
269 #define BTRFS_DEFRAG_BATCH      1024
270
271 static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
272                                     struct inode_defrag *defrag)
273 {
274         struct btrfs_root *inode_root;
275         struct inode *inode;
276         struct btrfs_key key;
277         struct btrfs_ioctl_defrag_range_args range;
278         int num_defrag;
279         int index;
280         int ret;
281
282         /* get the inode */
283         key.objectid = defrag->root;
284         key.type = BTRFS_ROOT_ITEM_KEY;
285         key.offset = (u64)-1;
286
287         index = srcu_read_lock(&fs_info->subvol_srcu);
288
289         inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
290         if (IS_ERR(inode_root)) {
291                 ret = PTR_ERR(inode_root);
292                 goto cleanup;
293         }
294
295         key.objectid = defrag->ino;
296         key.type = BTRFS_INODE_ITEM_KEY;
297         key.offset = 0;
298         inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
299         if (IS_ERR(inode)) {
300                 ret = PTR_ERR(inode);
301                 goto cleanup;
302         }
303         srcu_read_unlock(&fs_info->subvol_srcu, index);
304
305         /* do a chunk of defrag */
306         clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
307         memset(&range, 0, sizeof(range));
308         range.len = (u64)-1;
309         range.start = defrag->last_offset;
310
311         sb_start_write(fs_info->sb);
312         num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
313                                        BTRFS_DEFRAG_BATCH);
314         sb_end_write(fs_info->sb);
315         /*
316          * if we filled the whole defrag batch, there
317          * must be more work to do.  Queue this defrag
318          * again
319          */
320         if (num_defrag == BTRFS_DEFRAG_BATCH) {
321                 defrag->last_offset = range.start;
322                 btrfs_requeue_inode_defrag(BTRFS_I(inode), defrag);
323         } else if (defrag->last_offset && !defrag->cycled) {
324                 /*
325                  * we didn't fill our defrag batch, but
326                  * we didn't start at zero.  Make sure we loop
327                  * around to the start of the file.
328                  */
329                 defrag->last_offset = 0;
330                 defrag->cycled = 1;
331                 btrfs_requeue_inode_defrag(BTRFS_I(inode), defrag);
332         } else {
333                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
334         }
335
336         iput(inode);
337         return 0;
338 cleanup:
339         srcu_read_unlock(&fs_info->subvol_srcu, index);
340         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
341         return ret;
342 }
343
344 /*
345  * run through the list of inodes in the FS that need
346  * defragging
347  */
348 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
349 {
350         struct inode_defrag *defrag;
351         u64 first_ino = 0;
352         u64 root_objectid = 0;
353
354         atomic_inc(&fs_info->defrag_running);
355         while (1) {
356                 /* Pause the auto defragger. */
357                 if (test_bit(BTRFS_FS_STATE_REMOUNTING,
358                              &fs_info->fs_state))
359                         break;
360
361                 if (!__need_auto_defrag(fs_info))
362                         break;
363
364                 /* find an inode to defrag */
365                 defrag = btrfs_pick_defrag_inode(fs_info, root_objectid,
366                                                  first_ino);
367                 if (!defrag) {
368                         if (root_objectid || first_ino) {
369                                 root_objectid = 0;
370                                 first_ino = 0;
371                                 continue;
372                         } else {
373                                 break;
374                         }
375                 }
376
377                 first_ino = defrag->ino + 1;
378                 root_objectid = defrag->root;
379
380                 __btrfs_run_defrag_inode(fs_info, defrag);
381         }
382         atomic_dec(&fs_info->defrag_running);
383
384         /*
385          * during unmount, we use the transaction_wait queue to
386          * wait for the defragger to stop
387          */
388         wake_up(&fs_info->transaction_wait);
389         return 0;
390 }
391
392 /* simple helper to fault in pages and copy.  This should go away
393  * and be replaced with calls into generic code.
394  */
395 static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes,
396                                          struct page **prepared_pages,
397                                          struct iov_iter *i)
398 {
399         size_t copied = 0;
400         size_t total_copied = 0;
401         int pg = 0;
402         int offset = offset_in_page(pos);
403
404         while (write_bytes > 0) {
405                 size_t count = min_t(size_t,
406                                      PAGE_SIZE - offset, write_bytes);
407                 struct page *page = prepared_pages[pg];
408                 /*
409                  * Copy data from userspace to the current page
410                  */
411                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
412
413                 /* Flush processor's dcache for this page */
414                 flush_dcache_page(page);
415
416                 /*
417                  * if we get a partial write, we can end up with
418                  * partially up to date pages.  These add
419                  * a lot of complexity, so make sure they don't
420                  * happen by forcing this copy to be retried.
421                  *
422                  * The rest of the btrfs_file_write code will fall
423                  * back to page at a time copies after we return 0.
424                  */
425                 if (!PageUptodate(page) && copied < count)
426                         copied = 0;
427
428                 iov_iter_advance(i, copied);
429                 write_bytes -= copied;
430                 total_copied += copied;
431
432                 /* Return to btrfs_file_write_iter to fault page */
433                 if (unlikely(copied == 0))
434                         break;
435
436                 if (copied < PAGE_SIZE - offset) {
437                         offset += copied;
438                 } else {
439                         pg++;
440                         offset = 0;
441                 }
442         }
443         return total_copied;
444 }
445
446 /*
447  * unlocks pages after btrfs_file_write is done with them
448  */
449 static void btrfs_drop_pages(struct page **pages, size_t num_pages)
450 {
451         size_t i;
452         for (i = 0; i < num_pages; i++) {
453                 /* page checked is some magic around finding pages that
454                  * have been modified without going through btrfs_set_page_dirty
455                  * clear it here. There should be no need to mark the pages
456                  * accessed as prepare_pages should have marked them accessed
457                  * in prepare_pages via find_or_create_page()
458                  */
459                 ClearPageChecked(pages[i]);
460                 unlock_page(pages[i]);
461                 put_page(pages[i]);
462         }
463 }
464
465 static int btrfs_find_new_delalloc_bytes(struct btrfs_inode *inode,
466                                          const u64 start,
467                                          const u64 len,
468                                          struct extent_state **cached_state)
469 {
470         u64 search_start = start;
471         const u64 end = start + len - 1;
472
473         while (search_start < end) {
474                 const u64 search_len = end - search_start + 1;
475                 struct extent_map *em;
476                 u64 em_len;
477                 int ret = 0;
478
479                 em = btrfs_get_extent(inode, NULL, 0, search_start,
480                                       search_len, 0);
481                 if (IS_ERR(em))
482                         return PTR_ERR(em);
483
484                 if (em->block_start != EXTENT_MAP_HOLE)
485                         goto next;
486
487                 em_len = em->len;
488                 if (em->start < search_start)
489                         em_len -= search_start - em->start;
490                 if (em_len > search_len)
491                         em_len = search_len;
492
493                 ret = set_extent_bit(&inode->io_tree, search_start,
494                                      search_start + em_len - 1,
495                                      EXTENT_DELALLOC_NEW,
496                                      NULL, cached_state, GFP_NOFS);
497 next:
498                 search_start = extent_map_end(em);
499                 free_extent_map(em);
500                 if (ret)
501                         return ret;
502         }
503         return 0;
504 }
505
506 /*
507  * after copy_from_user, pages need to be dirtied and we need to make
508  * sure holes are created between the current EOF and the start of
509  * any next extents (if required).
510  *
511  * this also makes the decision about creating an inline extent vs
512  * doing real data extents, marking pages dirty and delalloc as required.
513  */
514 int btrfs_dirty_pages(struct inode *inode, struct page **pages,
515                       size_t num_pages, loff_t pos, size_t write_bytes,
516                       struct extent_state **cached)
517 {
518         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
519         int err = 0;
520         int i;
521         u64 num_bytes;
522         u64 start_pos;
523         u64 end_of_last_block;
524         u64 end_pos = pos + write_bytes;
525         loff_t isize = i_size_read(inode);
526         unsigned int extra_bits = 0;
527
528         start_pos = pos & ~((u64) fs_info->sectorsize - 1);
529         num_bytes = round_up(write_bytes + pos - start_pos,
530                              fs_info->sectorsize);
531
532         end_of_last_block = start_pos + num_bytes - 1;
533
534         /*
535          * The pages may have already been dirty, clear out old accounting so
536          * we can set things up properly
537          */
538         clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos, end_of_last_block,
539                          EXTENT_DIRTY | EXTENT_DELALLOC |
540                          EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0, cached);
541
542         if (!btrfs_is_free_space_inode(BTRFS_I(inode))) {
543                 if (start_pos >= isize &&
544                     !(BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC)) {
545                         /*
546                          * There can't be any extents following eof in this case
547                          * so just set the delalloc new bit for the range
548                          * directly.
549                          */
550                         extra_bits |= EXTENT_DELALLOC_NEW;
551                 } else {
552                         err = btrfs_find_new_delalloc_bytes(BTRFS_I(inode),
553                                                             start_pos,
554                                                             num_bytes, cached);
555                         if (err)
556                                 return err;
557                 }
558         }
559
560         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
561                                         extra_bits, cached, 0);
562         if (err)
563                 return err;
564
565         for (i = 0; i < num_pages; i++) {
566                 struct page *p = pages[i];
567                 SetPageUptodate(p);
568                 ClearPageChecked(p);
569                 set_page_dirty(p);
570         }
571
572         /*
573          * we've only changed i_size in ram, and we haven't updated
574          * the disk i_size.  There is no need to log the inode
575          * at this time.
576          */
577         if (end_pos > isize)
578                 i_size_write(inode, end_pos);
579         return 0;
580 }
581
582 /*
583  * this drops all the extents in the cache that intersect the range
584  * [start, end].  Existing extents are split as required.
585  */
586 void btrfs_drop_extent_cache(struct btrfs_inode *inode, u64 start, u64 end,
587                              int skip_pinned)
588 {
589         struct extent_map *em;
590         struct extent_map *split = NULL;
591         struct extent_map *split2 = NULL;
592         struct extent_map_tree *em_tree = &inode->extent_tree;
593         u64 len = end - start + 1;
594         u64 gen;
595         int ret;
596         int testend = 1;
597         unsigned long flags;
598         int compressed = 0;
599         bool modified;
600
601         WARN_ON(end < start);
602         if (end == (u64)-1) {
603                 len = (u64)-1;
604                 testend = 0;
605         }
606         while (1) {
607                 int no_splits = 0;
608
609                 modified = false;
610                 if (!split)
611                         split = alloc_extent_map();
612                 if (!split2)
613                         split2 = alloc_extent_map();
614                 if (!split || !split2)
615                         no_splits = 1;
616
617                 write_lock(&em_tree->lock);
618                 em = lookup_extent_mapping(em_tree, start, len);
619                 if (!em) {
620                         write_unlock(&em_tree->lock);
621                         break;
622                 }
623                 flags = em->flags;
624                 gen = em->generation;
625                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
626                         if (testend && em->start + em->len >= start + len) {
627                                 free_extent_map(em);
628                                 write_unlock(&em_tree->lock);
629                                 break;
630                         }
631                         start = em->start + em->len;
632                         if (testend)
633                                 len = start + len - (em->start + em->len);
634                         free_extent_map(em);
635                         write_unlock(&em_tree->lock);
636                         continue;
637                 }
638                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
639                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
640                 clear_bit(EXTENT_FLAG_LOGGING, &flags);
641                 modified = !list_empty(&em->list);
642                 if (no_splits)
643                         goto next;
644
645                 if (em->start < start) {
646                         split->start = em->start;
647                         split->len = start - em->start;
648
649                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
650                                 split->orig_start = em->orig_start;
651                                 split->block_start = em->block_start;
652
653                                 if (compressed)
654                                         split->block_len = em->block_len;
655                                 else
656                                         split->block_len = split->len;
657                                 split->orig_block_len = max(split->block_len,
658                                                 em->orig_block_len);
659                                 split->ram_bytes = em->ram_bytes;
660                         } else {
661                                 split->orig_start = split->start;
662                                 split->block_len = 0;
663                                 split->block_start = em->block_start;
664                                 split->orig_block_len = 0;
665                                 split->ram_bytes = split->len;
666                         }
667
668                         split->generation = gen;
669                         split->bdev = em->bdev;
670                         split->flags = flags;
671                         split->compress_type = em->compress_type;
672                         replace_extent_mapping(em_tree, em, split, modified);
673                         free_extent_map(split);
674                         split = split2;
675                         split2 = NULL;
676                 }
677                 if (testend && em->start + em->len > start + len) {
678                         u64 diff = start + len - em->start;
679
680                         split->start = start + len;
681                         split->len = em->start + em->len - (start + len);
682                         split->bdev = em->bdev;
683                         split->flags = flags;
684                         split->compress_type = em->compress_type;
685                         split->generation = gen;
686
687                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
688                                 split->orig_block_len = max(em->block_len,
689                                                     em->orig_block_len);
690
691                                 split->ram_bytes = em->ram_bytes;
692                                 if (compressed) {
693                                         split->block_len = em->block_len;
694                                         split->block_start = em->block_start;
695                                         split->orig_start = em->orig_start;
696                                 } else {
697                                         split->block_len = split->len;
698                                         split->block_start = em->block_start
699                                                 + diff;
700                                         split->orig_start = em->orig_start;
701                                 }
702                         } else {
703                                 split->ram_bytes = split->len;
704                                 split->orig_start = split->start;
705                                 split->block_len = 0;
706                                 split->block_start = em->block_start;
707                                 split->orig_block_len = 0;
708                         }
709
710                         if (extent_map_in_tree(em)) {
711                                 replace_extent_mapping(em_tree, em, split,
712                                                        modified);
713                         } else {
714                                 ret = add_extent_mapping(em_tree, split,
715                                                          modified);
716                                 ASSERT(ret == 0); /* Logic error */
717                         }
718                         free_extent_map(split);
719                         split = NULL;
720                 }
721 next:
722                 if (extent_map_in_tree(em))
723                         remove_extent_mapping(em_tree, em);
724                 write_unlock(&em_tree->lock);
725
726                 /* once for us */
727                 free_extent_map(em);
728                 /* once for the tree*/
729                 free_extent_map(em);
730         }
731         if (split)
732                 free_extent_map(split);
733         if (split2)
734                 free_extent_map(split2);
735 }
736
737 /*
738  * this is very complex, but the basic idea is to drop all extents
739  * in the range start - end.  hint_block is filled in with a block number
740  * that would be a good hint to the block allocator for this file.
741  *
742  * If an extent intersects the range but is not entirely inside the range
743  * it is either truncated or split.  Anything entirely inside the range
744  * is deleted from the tree.
745  */
746 int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
747                          struct btrfs_root *root, struct inode *inode,
748                          struct btrfs_path *path, u64 start, u64 end,
749                          u64 *drop_end, int drop_cache,
750                          int replace_extent,
751                          u32 extent_item_size,
752                          int *key_inserted)
753 {
754         struct btrfs_fs_info *fs_info = root->fs_info;
755         struct extent_buffer *leaf;
756         struct btrfs_file_extent_item *fi;
757         struct btrfs_ref ref = { 0 };
758         struct btrfs_key key;
759         struct btrfs_key new_key;
760         u64 ino = btrfs_ino(BTRFS_I(inode));
761         u64 search_start = start;
762         u64 disk_bytenr = 0;
763         u64 num_bytes = 0;
764         u64 extent_offset = 0;
765         u64 extent_end = 0;
766         u64 last_end = start;
767         int del_nr = 0;
768         int del_slot = 0;
769         int extent_type;
770         int recow;
771         int ret;
772         int modify_tree = -1;
773         int update_refs;
774         int found = 0;
775         int leafs_visited = 0;
776
777         if (drop_cache)
778                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end - 1, 0);
779
780         if (start >= BTRFS_I(inode)->disk_i_size && !replace_extent)
781                 modify_tree = 0;
782
783         update_refs = (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
784                        root == fs_info->tree_root);
785         while (1) {
786                 recow = 0;
787                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
788                                                search_start, modify_tree);
789                 if (ret < 0)
790                         break;
791                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
792                         leaf = path->nodes[0];
793                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
794                         if (key.objectid == ino &&
795                             key.type == BTRFS_EXTENT_DATA_KEY)
796                                 path->slots[0]--;
797                 }
798                 ret = 0;
799                 leafs_visited++;
800 next_slot:
801                 leaf = path->nodes[0];
802                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
803                         BUG_ON(del_nr > 0);
804                         ret = btrfs_next_leaf(root, path);
805                         if (ret < 0)
806                                 break;
807                         if (ret > 0) {
808                                 ret = 0;
809                                 break;
810                         }
811                         leafs_visited++;
812                         leaf = path->nodes[0];
813                         recow = 1;
814                 }
815
816                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
817
818                 if (key.objectid > ino)
819                         break;
820                 if (WARN_ON_ONCE(key.objectid < ino) ||
821                     key.type < BTRFS_EXTENT_DATA_KEY) {
822                         ASSERT(del_nr == 0);
823                         path->slots[0]++;
824                         goto next_slot;
825                 }
826                 if (key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
827                         break;
828
829                 fi = btrfs_item_ptr(leaf, path->slots[0],
830                                     struct btrfs_file_extent_item);
831                 extent_type = btrfs_file_extent_type(leaf, fi);
832
833                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
834                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
835                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
836                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
837                         extent_offset = btrfs_file_extent_offset(leaf, fi);
838                         extent_end = key.offset +
839                                 btrfs_file_extent_num_bytes(leaf, fi);
840                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
841                         extent_end = key.offset +
842                                 btrfs_file_extent_ram_bytes(leaf, fi);
843                 } else {
844                         /* can't happen */
845                         BUG();
846                 }
847
848                 /*
849                  * Don't skip extent items representing 0 byte lengths. They
850                  * used to be created (bug) if while punching holes we hit
851                  * -ENOSPC condition. So if we find one here, just ensure we
852                  * delete it, otherwise we would insert a new file extent item
853                  * with the same key (offset) as that 0 bytes length file
854                  * extent item in the call to setup_items_for_insert() later
855                  * in this function.
856                  */
857                 if (extent_end == key.offset && extent_end >= search_start) {
858                         last_end = extent_end;
859                         goto delete_extent_item;
860                 }
861
862                 if (extent_end <= search_start) {
863                         path->slots[0]++;
864                         goto next_slot;
865                 }
866
867                 found = 1;
868                 search_start = max(key.offset, start);
869                 if (recow || !modify_tree) {
870                         modify_tree = -1;
871                         btrfs_release_path(path);
872                         continue;
873                 }
874
875                 /*
876                  *     | - range to drop - |
877                  *  | -------- extent -------- |
878                  */
879                 if (start > key.offset && end < extent_end) {
880                         BUG_ON(del_nr > 0);
881                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
882                                 ret = -EOPNOTSUPP;
883                                 break;
884                         }
885
886                         memcpy(&new_key, &key, sizeof(new_key));
887                         new_key.offset = start;
888                         ret = btrfs_duplicate_item(trans, root, path,
889                                                    &new_key);
890                         if (ret == -EAGAIN) {
891                                 btrfs_release_path(path);
892                                 continue;
893                         }
894                         if (ret < 0)
895                                 break;
896
897                         leaf = path->nodes[0];
898                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
899                                             struct btrfs_file_extent_item);
900                         btrfs_set_file_extent_num_bytes(leaf, fi,
901                                                         start - key.offset);
902
903                         fi = btrfs_item_ptr(leaf, path->slots[0],
904                                             struct btrfs_file_extent_item);
905
906                         extent_offset += start - key.offset;
907                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
908                         btrfs_set_file_extent_num_bytes(leaf, fi,
909                                                         extent_end - start);
910                         btrfs_mark_buffer_dirty(leaf);
911
912                         if (update_refs && disk_bytenr > 0) {
913                                 btrfs_init_generic_ref(&ref,
914                                                 BTRFS_ADD_DELAYED_REF,
915                                                 disk_bytenr, num_bytes, 0);
916                                 btrfs_init_data_ref(&ref,
917                                                 root->root_key.objectid,
918                                                 new_key.objectid,
919                                                 start - extent_offset);
920                                 ret = btrfs_inc_extent_ref(trans, &ref);
921                                 BUG_ON(ret); /* -ENOMEM */
922                         }
923                         key.offset = start;
924                 }
925                 /*
926                  * From here on out we will have actually dropped something, so
927                  * last_end can be updated.
928                  */
929                 last_end = extent_end;
930
931                 /*
932                  *  | ---- range to drop ----- |
933                  *      | -------- extent -------- |
934                  */
935                 if (start <= key.offset && end < extent_end) {
936                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
937                                 ret = -EOPNOTSUPP;
938                                 break;
939                         }
940
941                         memcpy(&new_key, &key, sizeof(new_key));
942                         new_key.offset = end;
943                         btrfs_set_item_key_safe(fs_info, path, &new_key);
944
945                         extent_offset += end - key.offset;
946                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
947                         btrfs_set_file_extent_num_bytes(leaf, fi,
948                                                         extent_end - end);
949                         btrfs_mark_buffer_dirty(leaf);
950                         if (update_refs && disk_bytenr > 0)
951                                 inode_sub_bytes(inode, end - key.offset);
952                         break;
953                 }
954
955                 search_start = extent_end;
956                 /*
957                  *       | ---- range to drop ----- |
958                  *  | -------- extent -------- |
959                  */
960                 if (start > key.offset && end >= extent_end) {
961                         BUG_ON(del_nr > 0);
962                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
963                                 ret = -EOPNOTSUPP;
964                                 break;
965                         }
966
967                         btrfs_set_file_extent_num_bytes(leaf, fi,
968                                                         start - key.offset);
969                         btrfs_mark_buffer_dirty(leaf);
970                         if (update_refs && disk_bytenr > 0)
971                                 inode_sub_bytes(inode, extent_end - start);
972                         if (end == extent_end)
973                                 break;
974
975                         path->slots[0]++;
976                         goto next_slot;
977                 }
978
979                 /*
980                  *  | ---- range to drop ----- |
981                  *    | ------ extent ------ |
982                  */
983                 if (start <= key.offset && end >= extent_end) {
984 delete_extent_item:
985                         if (del_nr == 0) {
986                                 del_slot = path->slots[0];
987                                 del_nr = 1;
988                         } else {
989                                 BUG_ON(del_slot + del_nr != path->slots[0]);
990                                 del_nr++;
991                         }
992
993                         if (update_refs &&
994                             extent_type == BTRFS_FILE_EXTENT_INLINE) {
995                                 inode_sub_bytes(inode,
996                                                 extent_end - key.offset);
997                                 extent_end = ALIGN(extent_end,
998                                                    fs_info->sectorsize);
999                         } else if (update_refs && disk_bytenr > 0) {
1000                                 btrfs_init_generic_ref(&ref,
1001                                                 BTRFS_DROP_DELAYED_REF,
1002                                                 disk_bytenr, num_bytes, 0);
1003                                 btrfs_init_data_ref(&ref,
1004                                                 root->root_key.objectid,
1005                                                 key.objectid,
1006                                                 key.offset - extent_offset);
1007                                 ret = btrfs_free_extent(trans, &ref);
1008                                 BUG_ON(ret); /* -ENOMEM */
1009                                 inode_sub_bytes(inode,
1010                                                 extent_end - key.offset);
1011                         }
1012
1013                         if (end == extent_end)
1014                                 break;
1015
1016                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
1017                                 path->slots[0]++;
1018                                 goto next_slot;
1019                         }
1020
1021                         ret = btrfs_del_items(trans, root, path, del_slot,
1022                                               del_nr);
1023                         if (ret) {
1024                                 btrfs_abort_transaction(trans, ret);
1025                                 break;
1026                         }
1027
1028                         del_nr = 0;
1029                         del_slot = 0;
1030
1031                         btrfs_release_path(path);
1032                         continue;
1033                 }
1034
1035                 BUG();
1036         }
1037
1038         if (!ret && del_nr > 0) {
1039                 /*
1040                  * Set path->slots[0] to first slot, so that after the delete
1041                  * if items are move off from our leaf to its immediate left or
1042                  * right neighbor leafs, we end up with a correct and adjusted
1043                  * path->slots[0] for our insertion (if replace_extent != 0).
1044                  */
1045                 path->slots[0] = del_slot;
1046                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1047                 if (ret)
1048                         btrfs_abort_transaction(trans, ret);
1049         }
1050
1051         leaf = path->nodes[0];
1052         /*
1053          * If btrfs_del_items() was called, it might have deleted a leaf, in
1054          * which case it unlocked our path, so check path->locks[0] matches a
1055          * write lock.
1056          */
1057         if (!ret && replace_extent && leafs_visited == 1 &&
1058             (path->locks[0] == BTRFS_WRITE_LOCK_BLOCKING ||
1059              path->locks[0] == BTRFS_WRITE_LOCK) &&
1060             btrfs_leaf_free_space(leaf) >=
1061             sizeof(struct btrfs_item) + extent_item_size) {
1062
1063                 key.objectid = ino;
1064                 key.type = BTRFS_EXTENT_DATA_KEY;
1065                 key.offset = start;
1066                 if (!del_nr && path->slots[0] < btrfs_header_nritems(leaf)) {
1067                         struct btrfs_key slot_key;
1068
1069                         btrfs_item_key_to_cpu(leaf, &slot_key, path->slots[0]);
1070                         if (btrfs_comp_cpu_keys(&key, &slot_key) > 0)
1071                                 path->slots[0]++;
1072                 }
1073                 setup_items_for_insert(root, path, &key,
1074                                        &extent_item_size,
1075                                        extent_item_size,
1076                                        sizeof(struct btrfs_item) +
1077                                        extent_item_size, 1);
1078                 *key_inserted = 1;
1079         }
1080
1081         if (!replace_extent || !(*key_inserted))
1082                 btrfs_release_path(path);
1083         if (drop_end)
1084                 *drop_end = found ? min(end, last_end) : end;
1085         return ret;
1086 }
1087
1088 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
1089                        struct btrfs_root *root, struct inode *inode, u64 start,
1090                        u64 end, int drop_cache)
1091 {
1092         struct btrfs_path *path;
1093         int ret;
1094
1095         path = btrfs_alloc_path();
1096         if (!path)
1097                 return -ENOMEM;
1098         ret = __btrfs_drop_extents(trans, root, inode, path, start, end, NULL,
1099                                    drop_cache, 0, 0, NULL);
1100         btrfs_free_path(path);
1101         return ret;
1102 }
1103
1104 static int extent_mergeable(struct extent_buffer *leaf, int slot,
1105                             u64 objectid, u64 bytenr, u64 orig_offset,
1106                             u64 *start, u64 *end)
1107 {
1108         struct btrfs_file_extent_item *fi;
1109         struct btrfs_key key;
1110         u64 extent_end;
1111
1112         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
1113                 return 0;
1114
1115         btrfs_item_key_to_cpu(leaf, &key, slot);
1116         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
1117                 return 0;
1118
1119         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1120         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
1121             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
1122             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
1123             btrfs_file_extent_compression(leaf, fi) ||
1124             btrfs_file_extent_encryption(leaf, fi) ||
1125             btrfs_file_extent_other_encoding(leaf, fi))
1126                 return 0;
1127
1128         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1129         if ((*start && *start != key.offset) || (*end && *end != extent_end))
1130                 return 0;
1131
1132         *start = key.offset;
1133         *end = extent_end;
1134         return 1;
1135 }
1136
1137 /*
1138  * Mark extent in the range start - end as written.
1139  *
1140  * This changes extent type from 'pre-allocated' to 'regular'. If only
1141  * part of extent is marked as written, the extent will be split into
1142  * two or three.
1143  */
1144 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
1145                               struct btrfs_inode *inode, u64 start, u64 end)
1146 {
1147         struct btrfs_fs_info *fs_info = trans->fs_info;
1148         struct btrfs_root *root = inode->root;
1149         struct extent_buffer *leaf;
1150         struct btrfs_path *path;
1151         struct btrfs_file_extent_item *fi;
1152         struct btrfs_ref ref = { 0 };
1153         struct btrfs_key key;
1154         struct btrfs_key new_key;
1155         u64 bytenr;
1156         u64 num_bytes;
1157         u64 extent_end;
1158         u64 orig_offset;
1159         u64 other_start;
1160         u64 other_end;
1161         u64 split;
1162         int del_nr = 0;
1163         int del_slot = 0;
1164         int recow;
1165         int ret;
1166         u64 ino = btrfs_ino(inode);
1167
1168         path = btrfs_alloc_path();
1169         if (!path)
1170                 return -ENOMEM;
1171 again:
1172         recow = 0;
1173         split = start;
1174         key.objectid = ino;
1175         key.type = BTRFS_EXTENT_DATA_KEY;
1176         key.offset = split;
1177
1178         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1179         if (ret < 0)
1180                 goto out;
1181         if (ret > 0 && path->slots[0] > 0)
1182                 path->slots[0]--;
1183
1184         leaf = path->nodes[0];
1185         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1186         if (key.objectid != ino ||
1187             key.type != BTRFS_EXTENT_DATA_KEY) {
1188                 ret = -EINVAL;
1189                 btrfs_abort_transaction(trans, ret);
1190                 goto out;
1191         }
1192         fi = btrfs_item_ptr(leaf, path->slots[0],
1193                             struct btrfs_file_extent_item);
1194         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_PREALLOC) {
1195                 ret = -EINVAL;
1196                 btrfs_abort_transaction(trans, ret);
1197                 goto out;
1198         }
1199         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1200         if (key.offset > start || extent_end < end) {
1201                 ret = -EINVAL;
1202                 btrfs_abort_transaction(trans, ret);
1203                 goto out;
1204         }
1205
1206         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1207         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1208         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
1209         memcpy(&new_key, &key, sizeof(new_key));
1210
1211         if (start == key.offset && end < extent_end) {
1212                 other_start = 0;
1213                 other_end = start;
1214                 if (extent_mergeable(leaf, path->slots[0] - 1,
1215                                      ino, bytenr, orig_offset,
1216                                      &other_start, &other_end)) {
1217                         new_key.offset = end;
1218                         btrfs_set_item_key_safe(fs_info, path, &new_key);
1219                         fi = btrfs_item_ptr(leaf, path->slots[0],
1220                                             struct btrfs_file_extent_item);
1221                         btrfs_set_file_extent_generation(leaf, fi,
1222                                                          trans->transid);
1223                         btrfs_set_file_extent_num_bytes(leaf, fi,
1224                                                         extent_end - end);
1225                         btrfs_set_file_extent_offset(leaf, fi,
1226                                                      end - orig_offset);
1227                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1228                                             struct btrfs_file_extent_item);
1229                         btrfs_set_file_extent_generation(leaf, fi,
1230                                                          trans->transid);
1231                         btrfs_set_file_extent_num_bytes(leaf, fi,
1232                                                         end - other_start);
1233                         btrfs_mark_buffer_dirty(leaf);
1234                         goto out;
1235                 }
1236         }
1237
1238         if (start > key.offset && end == extent_end) {
1239                 other_start = end;
1240                 other_end = 0;
1241                 if (extent_mergeable(leaf, path->slots[0] + 1,
1242                                      ino, bytenr, orig_offset,
1243                                      &other_start, &other_end)) {
1244                         fi = btrfs_item_ptr(leaf, path->slots[0],
1245                                             struct btrfs_file_extent_item);
1246                         btrfs_set_file_extent_num_bytes(leaf, fi,
1247                                                         start - key.offset);
1248                         btrfs_set_file_extent_generation(leaf, fi,
1249                                                          trans->transid);
1250                         path->slots[0]++;
1251                         new_key.offset = start;
1252                         btrfs_set_item_key_safe(fs_info, path, &new_key);
1253
1254                         fi = btrfs_item_ptr(leaf, path->slots[0],
1255                                             struct btrfs_file_extent_item);
1256                         btrfs_set_file_extent_generation(leaf, fi,
1257                                                          trans->transid);
1258                         btrfs_set_file_extent_num_bytes(leaf, fi,
1259                                                         other_end - start);
1260                         btrfs_set_file_extent_offset(leaf, fi,
1261                                                      start - orig_offset);
1262                         btrfs_mark_buffer_dirty(leaf);
1263                         goto out;
1264                 }
1265         }
1266
1267         while (start > key.offset || end < extent_end) {
1268                 if (key.offset == start)
1269                         split = end;
1270
1271                 new_key.offset = split;
1272                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
1273                 if (ret == -EAGAIN) {
1274                         btrfs_release_path(path);
1275                         goto again;
1276                 }
1277                 if (ret < 0) {
1278                         btrfs_abort_transaction(trans, ret);
1279                         goto out;
1280                 }
1281
1282                 leaf = path->nodes[0];
1283                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1284                                     struct btrfs_file_extent_item);
1285                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1286                 btrfs_set_file_extent_num_bytes(leaf, fi,
1287                                                 split - key.offset);
1288
1289                 fi = btrfs_item_ptr(leaf, path->slots[0],
1290                                     struct btrfs_file_extent_item);
1291
1292                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1293                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
1294                 btrfs_set_file_extent_num_bytes(leaf, fi,
1295                                                 extent_end - split);
1296                 btrfs_mark_buffer_dirty(leaf);
1297
1298                 btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, bytenr,
1299                                        num_bytes, 0);
1300                 btrfs_init_data_ref(&ref, root->root_key.objectid, ino,
1301                                     orig_offset);
1302                 ret = btrfs_inc_extent_ref(trans, &ref);
1303                 if (ret) {
1304                         btrfs_abort_transaction(trans, ret);
1305                         goto out;
1306                 }
1307
1308                 if (split == start) {
1309                         key.offset = start;
1310                 } else {
1311                         if (start != key.offset) {
1312                                 ret = -EINVAL;
1313                                 btrfs_abort_transaction(trans, ret);
1314                                 goto out;
1315                         }
1316                         path->slots[0]--;
1317                         extent_end = end;
1318                 }
1319                 recow = 1;
1320         }
1321
1322         other_start = end;
1323         other_end = 0;
1324         btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, bytenr,
1325                                num_bytes, 0);
1326         btrfs_init_data_ref(&ref, root->root_key.objectid, ino, orig_offset);
1327         if (extent_mergeable(leaf, path->slots[0] + 1,
1328                              ino, bytenr, orig_offset,
1329                              &other_start, &other_end)) {
1330                 if (recow) {
1331                         btrfs_release_path(path);
1332                         goto again;
1333                 }
1334                 extent_end = other_end;
1335                 del_slot = path->slots[0] + 1;
1336                 del_nr++;
1337                 ret = btrfs_free_extent(trans, &ref);
1338                 if (ret) {
1339                         btrfs_abort_transaction(trans, ret);
1340                         goto out;
1341                 }
1342         }
1343         other_start = 0;
1344         other_end = start;
1345         if (extent_mergeable(leaf, path->slots[0] - 1,
1346                              ino, bytenr, orig_offset,
1347                              &other_start, &other_end)) {
1348                 if (recow) {
1349                         btrfs_release_path(path);
1350                         goto again;
1351                 }
1352                 key.offset = other_start;
1353                 del_slot = path->slots[0];
1354                 del_nr++;
1355                 ret = btrfs_free_extent(trans, &ref);
1356                 if (ret) {
1357                         btrfs_abort_transaction(trans, ret);
1358                         goto out;
1359                 }
1360         }
1361         if (del_nr == 0) {
1362                 fi = btrfs_item_ptr(leaf, path->slots[0],
1363                            struct btrfs_file_extent_item);
1364                 btrfs_set_file_extent_type(leaf, fi,
1365                                            BTRFS_FILE_EXTENT_REG);
1366                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1367                 btrfs_mark_buffer_dirty(leaf);
1368         } else {
1369                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1370                            struct btrfs_file_extent_item);
1371                 btrfs_set_file_extent_type(leaf, fi,
1372                                            BTRFS_FILE_EXTENT_REG);
1373                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1374                 btrfs_set_file_extent_num_bytes(leaf, fi,
1375                                                 extent_end - key.offset);
1376                 btrfs_mark_buffer_dirty(leaf);
1377
1378                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1379                 if (ret < 0) {
1380                         btrfs_abort_transaction(trans, ret);
1381                         goto out;
1382                 }
1383         }
1384 out:
1385         btrfs_free_path(path);
1386         return 0;
1387 }
1388
1389 /*
1390  * on error we return an unlocked page and the error value
1391  * on success we return a locked page and 0
1392  */
1393 static int prepare_uptodate_page(struct inode *inode,
1394                                  struct page *page, u64 pos,
1395                                  bool force_uptodate)
1396 {
1397         int ret = 0;
1398
1399         if (((pos & (PAGE_SIZE - 1)) || force_uptodate) &&
1400             !PageUptodate(page)) {
1401                 ret = btrfs_readpage(NULL, page);
1402                 if (ret)
1403                         return ret;
1404                 lock_page(page);
1405                 if (!PageUptodate(page)) {
1406                         unlock_page(page);
1407                         return -EIO;
1408                 }
1409                 if (page->mapping != inode->i_mapping) {
1410                         unlock_page(page);
1411                         return -EAGAIN;
1412                 }
1413         }
1414         return 0;
1415 }
1416
1417 /*
1418  * this just gets pages into the page cache and locks them down.
1419  */
1420 static noinline int prepare_pages(struct inode *inode, struct page **pages,
1421                                   size_t num_pages, loff_t pos,
1422                                   size_t write_bytes, bool force_uptodate)
1423 {
1424         int i;
1425         unsigned long index = pos >> PAGE_SHIFT;
1426         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1427         int err = 0;
1428         int faili;
1429
1430         for (i = 0; i < num_pages; i++) {
1431 again:
1432                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1433                                                mask | __GFP_WRITE);
1434                 if (!pages[i]) {
1435                         faili = i - 1;
1436                         err = -ENOMEM;
1437                         goto fail;
1438                 }
1439
1440                 if (i == 0)
1441                         err = prepare_uptodate_page(inode, pages[i], pos,
1442                                                     force_uptodate);
1443                 if (!err && i == num_pages - 1)
1444                         err = prepare_uptodate_page(inode, pages[i],
1445                                                     pos + write_bytes, false);
1446                 if (err) {
1447                         put_page(pages[i]);
1448                         if (err == -EAGAIN) {
1449                                 err = 0;
1450                                 goto again;
1451                         }
1452                         faili = i - 1;
1453                         goto fail;
1454                 }
1455                 wait_on_page_writeback(pages[i]);
1456         }
1457
1458         return 0;
1459 fail:
1460         while (faili >= 0) {
1461                 unlock_page(pages[faili]);
1462                 put_page(pages[faili]);
1463                 faili--;
1464         }
1465         return err;
1466
1467 }
1468
1469 /*
1470  * This function locks the extent and properly waits for data=ordered extents
1471  * to finish before allowing the pages to be modified if need.
1472  *
1473  * The return value:
1474  * 1 - the extent is locked
1475  * 0 - the extent is not locked, and everything is OK
1476  * -EAGAIN - need re-prepare the pages
1477  * the other < 0 number - Something wrong happens
1478  */
1479 static noinline int
1480 lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages,
1481                                 size_t num_pages, loff_t pos,
1482                                 size_t write_bytes,
1483                                 u64 *lockstart, u64 *lockend,
1484                                 struct extent_state **cached_state)
1485 {
1486         struct btrfs_fs_info *fs_info = inode->root->fs_info;
1487         u64 start_pos;
1488         u64 last_pos;
1489         int i;
1490         int ret = 0;
1491
1492         start_pos = round_down(pos, fs_info->sectorsize);
1493         last_pos = start_pos
1494                 + round_up(pos + write_bytes - start_pos,
1495                            fs_info->sectorsize) - 1;
1496
1497         if (start_pos < inode->vfs_inode.i_size) {
1498                 struct btrfs_ordered_extent *ordered;
1499
1500                 lock_extent_bits(&inode->io_tree, start_pos, last_pos,
1501                                 cached_state);
1502                 ordered = btrfs_lookup_ordered_range(inode, start_pos,
1503                                                      last_pos - start_pos + 1);
1504                 if (ordered &&
1505                     ordered->file_offset + ordered->len > start_pos &&
1506                     ordered->file_offset <= last_pos) {
1507                         unlock_extent_cached(&inode->io_tree, start_pos,
1508                                         last_pos, cached_state);
1509                         for (i = 0; i < num_pages; i++) {
1510                                 unlock_page(pages[i]);
1511                                 put_page(pages[i]);
1512                         }
1513                         btrfs_start_ordered_extent(&inode->vfs_inode,
1514                                         ordered, 1);
1515                         btrfs_put_ordered_extent(ordered);
1516                         return -EAGAIN;
1517                 }
1518                 if (ordered)
1519                         btrfs_put_ordered_extent(ordered);
1520
1521                 *lockstart = start_pos;
1522                 *lockend = last_pos;
1523                 ret = 1;
1524         }
1525
1526         /*
1527          * It's possible the pages are dirty right now, but we don't want
1528          * to clean them yet because copy_from_user may catch a page fault
1529          * and we might have to fall back to one page at a time.  If that
1530          * happens, we'll unlock these pages and we'd have a window where
1531          * reclaim could sneak in and drop the once-dirty page on the floor
1532          * without writing it.
1533          *
1534          * We have the pages locked and the extent range locked, so there's
1535          * no way someone can start IO on any dirty pages in this range.
1536          *
1537          * We'll call btrfs_dirty_pages() later on, and that will flip around
1538          * delalloc bits and dirty the pages as required.
1539          */
1540         for (i = 0; i < num_pages; i++) {
1541                 set_page_extent_mapped(pages[i]);
1542                 WARN_ON(!PageLocked(pages[i]));
1543         }
1544
1545         return ret;
1546 }
1547
1548 static noinline int check_can_nocow(struct btrfs_inode *inode, loff_t pos,
1549                                     size_t *write_bytes)
1550 {
1551         struct btrfs_fs_info *fs_info = inode->root->fs_info;
1552         struct btrfs_root *root = inode->root;
1553         u64 lockstart, lockend;
1554         u64 num_bytes;
1555         int ret;
1556
1557         ret = btrfs_start_write_no_snapshotting(root);
1558         if (!ret)
1559                 return -EAGAIN;
1560
1561         lockstart = round_down(pos, fs_info->sectorsize);
1562         lockend = round_up(pos + *write_bytes,
1563                            fs_info->sectorsize) - 1;
1564
1565         btrfs_lock_and_flush_ordered_range(&inode->io_tree, inode, lockstart,
1566                                            lockend, NULL);
1567
1568         num_bytes = lockend - lockstart + 1;
1569         ret = can_nocow_extent(&inode->vfs_inode, lockstart, &num_bytes,
1570                         NULL, NULL, NULL);
1571         if (ret <= 0) {
1572                 ret = 0;
1573                 btrfs_end_write_no_snapshotting(root);
1574         } else {
1575                 *write_bytes = min_t(size_t, *write_bytes ,
1576                                      num_bytes - pos + lockstart);
1577         }
1578
1579         unlock_extent(&inode->io_tree, lockstart, lockend);
1580
1581         return ret;
1582 }
1583
1584 static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
1585                                                struct iov_iter *i)
1586 {
1587         struct file *file = iocb->ki_filp;
1588         loff_t pos = iocb->ki_pos;
1589         struct inode *inode = file_inode(file);
1590         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1591         struct btrfs_root *root = BTRFS_I(inode)->root;
1592         struct page **pages = NULL;
1593         struct extent_state *cached_state = NULL;
1594         struct extent_changeset *data_reserved = NULL;
1595         u64 release_bytes = 0;
1596         u64 lockstart;
1597         u64 lockend;
1598         size_t num_written = 0;
1599         int nrptrs;
1600         int ret = 0;
1601         bool only_release_metadata = false;
1602         bool force_page_uptodate = false;
1603
1604         nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE),
1605                         PAGE_SIZE / (sizeof(struct page *)));
1606         nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1607         nrptrs = max(nrptrs, 8);
1608         pages = kmalloc_array(nrptrs, sizeof(struct page *), GFP_KERNEL);
1609         if (!pages)
1610                 return -ENOMEM;
1611
1612         while (iov_iter_count(i) > 0) {
1613                 size_t offset = offset_in_page(pos);
1614                 size_t sector_offset;
1615                 size_t write_bytes = min(iov_iter_count(i),
1616                                          nrptrs * (size_t)PAGE_SIZE -
1617                                          offset);
1618                 size_t num_pages = DIV_ROUND_UP(write_bytes + offset,
1619                                                 PAGE_SIZE);
1620                 size_t reserve_bytes;
1621                 size_t dirty_pages;
1622                 size_t copied;
1623                 size_t dirty_sectors;
1624                 size_t num_sectors;
1625                 int extents_locked;
1626
1627                 WARN_ON(num_pages > nrptrs);
1628
1629                 /*
1630                  * Fault pages before locking them in prepare_pages
1631                  * to avoid recursive lock
1632                  */
1633                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1634                         ret = -EFAULT;
1635                         break;
1636                 }
1637
1638                 sector_offset = pos & (fs_info->sectorsize - 1);
1639                 reserve_bytes = round_up(write_bytes + sector_offset,
1640                                 fs_info->sectorsize);
1641
1642                 extent_changeset_release(data_reserved);
1643                 ret = btrfs_check_data_free_space(inode, &data_reserved, pos,
1644                                                   write_bytes);
1645                 if (ret < 0) {
1646                         if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
1647                                                       BTRFS_INODE_PREALLOC)) &&
1648                             check_can_nocow(BTRFS_I(inode), pos,
1649                                         &write_bytes) > 0) {
1650                                 /*
1651                                  * For nodata cow case, no need to reserve
1652                                  * data space.
1653                                  */
1654                                 only_release_metadata = true;
1655                                 /*
1656                                  * our prealloc extent may be smaller than
1657                                  * write_bytes, so scale down.
1658                                  */
1659                                 num_pages = DIV_ROUND_UP(write_bytes + offset,
1660                                                          PAGE_SIZE);
1661                                 reserve_bytes = round_up(write_bytes +
1662                                                          sector_offset,
1663                                                          fs_info->sectorsize);
1664                         } else {
1665                                 break;
1666                         }
1667                 }
1668
1669                 WARN_ON(reserve_bytes == 0);
1670                 ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
1671                                 reserve_bytes);
1672                 if (ret) {
1673                         if (!only_release_metadata)
1674                                 btrfs_free_reserved_data_space(inode,
1675                                                 data_reserved, pos,
1676                                                 write_bytes);
1677                         else
1678                                 btrfs_end_write_no_snapshotting(root);
1679                         break;
1680                 }
1681
1682                 release_bytes = reserve_bytes;
1683 again:
1684                 /*
1685                  * This is going to setup the pages array with the number of
1686                  * pages we want, so we don't really need to worry about the
1687                  * contents of pages from loop to loop
1688                  */
1689                 ret = prepare_pages(inode, pages, num_pages,
1690                                     pos, write_bytes,
1691                                     force_page_uptodate);
1692                 if (ret) {
1693                         btrfs_delalloc_release_extents(BTRFS_I(inode),
1694                                                        reserve_bytes, true);
1695                         break;
1696                 }
1697
1698                 extents_locked = lock_and_cleanup_extent_if_need(
1699                                 BTRFS_I(inode), pages,
1700                                 num_pages, pos, write_bytes, &lockstart,
1701                                 &lockend, &cached_state);
1702                 if (extents_locked < 0) {
1703                         if (extents_locked == -EAGAIN)
1704                                 goto again;
1705                         btrfs_delalloc_release_extents(BTRFS_I(inode),
1706                                                        reserve_bytes, true);
1707                         ret = extents_locked;
1708                         break;
1709                 }
1710
1711                 copied = btrfs_copy_from_user(pos, write_bytes, pages, i);
1712
1713                 num_sectors = BTRFS_BYTES_TO_BLKS(fs_info, reserve_bytes);
1714                 dirty_sectors = round_up(copied + sector_offset,
1715                                         fs_info->sectorsize);
1716                 dirty_sectors = BTRFS_BYTES_TO_BLKS(fs_info, dirty_sectors);
1717
1718                 /*
1719                  * if we have trouble faulting in the pages, fall
1720                  * back to one page at a time
1721                  */
1722                 if (copied < write_bytes)
1723                         nrptrs = 1;
1724
1725                 if (copied == 0) {
1726                         force_page_uptodate = true;
1727                         dirty_sectors = 0;
1728                         dirty_pages = 0;
1729                 } else {
1730                         force_page_uptodate = false;
1731                         dirty_pages = DIV_ROUND_UP(copied + offset,
1732                                                    PAGE_SIZE);
1733                 }
1734
1735                 if (num_sectors > dirty_sectors) {
1736                         /* release everything except the sectors we dirtied */
1737                         release_bytes -= dirty_sectors <<
1738                                                 fs_info->sb->s_blocksize_bits;
1739                         if (only_release_metadata) {
1740                                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
1741                                                         release_bytes, true);
1742                         } else {
1743                                 u64 __pos;
1744
1745                                 __pos = round_down(pos,
1746                                                    fs_info->sectorsize) +
1747                                         (dirty_pages << PAGE_SHIFT);
1748                                 btrfs_delalloc_release_space(inode,
1749                                                 data_reserved, __pos,
1750                                                 release_bytes, true);
1751                         }
1752                 }
1753
1754                 release_bytes = round_up(copied + sector_offset,
1755                                         fs_info->sectorsize);
1756
1757                 if (copied > 0)
1758                         ret = btrfs_dirty_pages(inode, pages, dirty_pages,
1759                                                 pos, copied, &cached_state);
1760                 if (extents_locked)
1761                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1762                                              lockstart, lockend, &cached_state);
1763                 btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes,
1764                                                true);
1765                 if (ret) {
1766                         btrfs_drop_pages(pages, num_pages);
1767                         break;
1768                 }
1769
1770                 release_bytes = 0;
1771                 if (only_release_metadata)
1772                         btrfs_end_write_no_snapshotting(root);
1773
1774                 if (only_release_metadata && copied > 0) {
1775                         lockstart = round_down(pos,
1776                                                fs_info->sectorsize);
1777                         lockend = round_up(pos + copied,
1778                                            fs_info->sectorsize) - 1;
1779
1780                         set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
1781                                        lockend, EXTENT_NORESERVE, NULL,
1782                                        NULL, GFP_NOFS);
1783                         only_release_metadata = false;
1784                 }
1785
1786                 btrfs_drop_pages(pages, num_pages);
1787
1788                 cond_resched();
1789
1790                 balance_dirty_pages_ratelimited(inode->i_mapping);
1791                 if (dirty_pages < (fs_info->nodesize >> PAGE_SHIFT) + 1)
1792                         btrfs_btree_balance_dirty(fs_info);
1793
1794                 pos += copied;
1795                 num_written += copied;
1796         }
1797
1798         kfree(pages);
1799
1800         if (release_bytes) {
1801                 if (only_release_metadata) {
1802                         btrfs_end_write_no_snapshotting(root);
1803                         btrfs_delalloc_release_metadata(BTRFS_I(inode),
1804                                         release_bytes, true);
1805                 } else {
1806                         btrfs_delalloc_release_space(inode, data_reserved,
1807                                         round_down(pos, fs_info->sectorsize),
1808                                         release_bytes, true);
1809                 }
1810         }
1811
1812         extent_changeset_free(data_reserved);
1813         return num_written ? num_written : ret;
1814 }
1815
1816 static ssize_t __btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
1817 {
1818         struct file *file = iocb->ki_filp;
1819         struct inode *inode = file_inode(file);
1820         loff_t pos;
1821         ssize_t written;
1822         ssize_t written_buffered;
1823         loff_t endbyte;
1824         int err;
1825
1826         written = generic_file_direct_write(iocb, from);
1827
1828         if (written < 0 || !iov_iter_count(from))
1829                 return written;
1830
1831         pos = iocb->ki_pos;
1832         written_buffered = btrfs_buffered_write(iocb, from);
1833         if (written_buffered < 0) {
1834                 err = written_buffered;
1835                 goto out;
1836         }
1837         /*
1838          * Ensure all data is persisted. We want the next direct IO read to be
1839          * able to read what was just written.
1840          */
1841         endbyte = pos + written_buffered - 1;
1842         err = btrfs_fdatawrite_range(inode, pos, endbyte);
1843         if (err)
1844                 goto out;
1845         err = filemap_fdatawait_range(inode->i_mapping, pos, endbyte);
1846         if (err)
1847                 goto out;
1848         written += written_buffered;
1849         iocb->ki_pos = pos + written_buffered;
1850         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_SHIFT,
1851                                  endbyte >> PAGE_SHIFT);
1852 out:
1853         return written ? written : err;
1854 }
1855
1856 static void update_time_for_write(struct inode *inode)
1857 {
1858         struct timespec64 now;
1859
1860         if (IS_NOCMTIME(inode))
1861                 return;
1862
1863         now = current_time(inode);
1864         if (!timespec64_equal(&inode->i_mtime, &now))
1865                 inode->i_mtime = now;
1866
1867         if (!timespec64_equal(&inode->i_ctime, &now))
1868                 inode->i_ctime = now;
1869
1870         if (IS_I_VERSION(inode))
1871                 inode_inc_iversion(inode);
1872 }
1873
1874 static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
1875                                     struct iov_iter *from)
1876 {
1877         struct file *file = iocb->ki_filp;
1878         struct inode *inode = file_inode(file);
1879         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1880         struct btrfs_root *root = BTRFS_I(inode)->root;
1881         u64 start_pos;
1882         u64 end_pos;
1883         ssize_t num_written = 0;
1884         bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
1885         ssize_t err;
1886         loff_t pos;
1887         size_t count = iov_iter_count(from);
1888         loff_t oldsize;
1889         int clean_page = 0;
1890
1891         if (!(iocb->ki_flags & IOCB_DIRECT) &&
1892             (iocb->ki_flags & IOCB_NOWAIT))
1893                 return -EOPNOTSUPP;
1894
1895         if (!inode_trylock(inode)) {
1896                 if (iocb->ki_flags & IOCB_NOWAIT)
1897                         return -EAGAIN;
1898                 inode_lock(inode);
1899         }
1900
1901         err = generic_write_checks(iocb, from);
1902         if (err <= 0) {
1903                 inode_unlock(inode);
1904                 return err;
1905         }
1906
1907         pos = iocb->ki_pos;
1908         if (iocb->ki_flags & IOCB_NOWAIT) {
1909                 /*
1910                  * We will allocate space in case nodatacow is not set,
1911                  * so bail
1912                  */
1913                 if (!(BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
1914                                               BTRFS_INODE_PREALLOC)) ||
1915                     check_can_nocow(BTRFS_I(inode), pos, &count) <= 0) {
1916                         inode_unlock(inode);
1917                         return -EAGAIN;
1918                 }
1919         }
1920
1921         current->backing_dev_info = inode_to_bdi(inode);
1922         err = file_remove_privs(file);
1923         if (err) {
1924                 inode_unlock(inode);
1925                 goto out;
1926         }
1927
1928         /*
1929          * If BTRFS flips readonly due to some impossible error
1930          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1931          * although we have opened a file as writable, we have
1932          * to stop this write operation to ensure FS consistency.
1933          */
1934         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
1935                 inode_unlock(inode);
1936                 err = -EROFS;
1937                 goto out;
1938         }
1939
1940         /*
1941          * We reserve space for updating the inode when we reserve space for the
1942          * extent we are going to write, so we will enospc out there.  We don't
1943          * need to start yet another transaction to update the inode as we will
1944          * update the inode when we finish writing whatever data we write.
1945          */
1946         update_time_for_write(inode);
1947
1948         start_pos = round_down(pos, fs_info->sectorsize);
1949         oldsize = i_size_read(inode);
1950         if (start_pos > oldsize) {
1951                 /* Expand hole size to cover write data, preventing empty gap */
1952                 end_pos = round_up(pos + count,
1953                                    fs_info->sectorsize);
1954                 err = btrfs_cont_expand(inode, oldsize, end_pos);
1955                 if (err) {
1956                         inode_unlock(inode);
1957                         goto out;
1958                 }
1959                 if (start_pos > round_up(oldsize, fs_info->sectorsize))
1960                         clean_page = 1;
1961         }
1962
1963         if (sync)
1964                 atomic_inc(&BTRFS_I(inode)->sync_writers);
1965
1966         if (iocb->ki_flags & IOCB_DIRECT) {
1967                 num_written = __btrfs_direct_write(iocb, from);
1968         } else {
1969                 num_written = btrfs_buffered_write(iocb, from);
1970                 if (num_written > 0)
1971                         iocb->ki_pos = pos + num_written;
1972                 if (clean_page)
1973                         pagecache_isize_extended(inode, oldsize,
1974                                                 i_size_read(inode));
1975         }
1976
1977         inode_unlock(inode);
1978
1979         /*
1980          * We also have to set last_sub_trans to the current log transid,
1981          * otherwise subsequent syncs to a file that's been synced in this
1982          * transaction will appear to have already occurred.
1983          */
1984         spin_lock(&BTRFS_I(inode)->lock);
1985         BTRFS_I(inode)->last_sub_trans = root->log_transid;
1986         spin_unlock(&BTRFS_I(inode)->lock);
1987         if (num_written > 0)
1988                 num_written = generic_write_sync(iocb, num_written);
1989
1990         if (sync)
1991                 atomic_dec(&BTRFS_I(inode)->sync_writers);
1992 out:
1993         current->backing_dev_info = NULL;
1994         return num_written ? num_written : err;
1995 }
1996
1997 int btrfs_release_file(struct inode *inode, struct file *filp)
1998 {
1999         struct btrfs_file_private *private = filp->private_data;
2000
2001         if (private && private->filldir_buf)
2002                 kfree(private->filldir_buf);
2003         kfree(private);
2004         filp->private_data = NULL;
2005
2006         /*
2007          * ordered_data_close is set by setattr when we are about to truncate
2008          * a file from a non-zero size to a zero size.  This tries to
2009          * flush down new bytes that may have been written if the
2010          * application were using truncate to replace a file in place.
2011          */
2012         if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
2013                                &BTRFS_I(inode)->runtime_flags))
2014                         filemap_flush(inode->i_mapping);
2015         return 0;
2016 }
2017
2018 static int start_ordered_ops(struct inode *inode, loff_t start, loff_t end)
2019 {
2020         int ret;
2021         struct blk_plug plug;
2022
2023         /*
2024          * This is only called in fsync, which would do synchronous writes, so
2025          * a plug can merge adjacent IOs as much as possible.  Esp. in case of
2026          * multiple disks using raid profile, a large IO can be split to
2027          * several segments of stripe length (currently 64K).
2028          */
2029         blk_start_plug(&plug);
2030         atomic_inc(&BTRFS_I(inode)->sync_writers);
2031         ret = btrfs_fdatawrite_range(inode, start, end);
2032         atomic_dec(&BTRFS_I(inode)->sync_writers);
2033         blk_finish_plug(&plug);
2034
2035         return ret;
2036 }
2037
2038 /*
2039  * fsync call for both files and directories.  This logs the inode into
2040  * the tree log instead of forcing full commits whenever possible.
2041  *
2042  * It needs to call filemap_fdatawait so that all ordered extent updates are
2043  * in the metadata btree are up to date for copying to the log.
2044  *
2045  * It drops the inode mutex before doing the tree log commit.  This is an
2046  * important optimization for directories because holding the mutex prevents
2047  * new operations on the dir while we write to disk.
2048  */
2049 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
2050 {
2051         struct dentry *dentry = file_dentry(file);
2052         struct inode *inode = d_inode(dentry);
2053         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2054         struct btrfs_root *root = BTRFS_I(inode)->root;
2055         struct btrfs_trans_handle *trans;
2056         struct btrfs_log_ctx ctx;
2057         int ret = 0, err;
2058         u64 len;
2059
2060         /*
2061          * If the inode needs a full sync, make sure we use a full range to
2062          * avoid log tree corruption, due to hole detection racing with ordered
2063          * extent completion for adjacent ranges, and assertion failures during
2064          * hole detection.
2065          */
2066         if (test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2067                      &BTRFS_I(inode)->runtime_flags)) {
2068                 start = 0;
2069                 end = LLONG_MAX;
2070         }
2071
2072         /*
2073          * The range length can be represented by u64, we have to do the typecasts
2074          * to avoid signed overflow if it's [0, LLONG_MAX] eg. from fsync()
2075          */
2076         len = (u64)end - (u64)start + 1;
2077         trace_btrfs_sync_file(file, datasync);
2078
2079         btrfs_init_log_ctx(&ctx, inode);
2080
2081         /*
2082          * We write the dirty pages in the range and wait until they complete
2083          * out of the ->i_mutex. If so, we can flush the dirty pages by
2084          * multi-task, and make the performance up.  See
2085          * btrfs_wait_ordered_range for an explanation of the ASYNC check.
2086          */
2087         ret = start_ordered_ops(inode, start, end);
2088         if (ret)
2089                 goto out;
2090
2091         inode_lock(inode);
2092
2093         /*
2094          * We take the dio_sem here because the tree log stuff can race with
2095          * lockless dio writes and get an extent map logged for an extent we
2096          * never waited on.  We need it this high up for lockdep reasons.
2097          */
2098         down_write(&BTRFS_I(inode)->dio_sem);
2099
2100         atomic_inc(&root->log_batch);
2101
2102         /*
2103          * Before we acquired the inode's lock, someone may have dirtied more
2104          * pages in the target range. We need to make sure that writeback for
2105          * any such pages does not start while we are logging the inode, because
2106          * if it does, any of the following might happen when we are not doing a
2107          * full inode sync:
2108          *
2109          * 1) We log an extent after its writeback finishes but before its
2110          *    checksums are added to the csum tree, leading to -EIO errors
2111          *    when attempting to read the extent after a log replay.
2112          *
2113          * 2) We can end up logging an extent before its writeback finishes.
2114          *    Therefore after the log replay we will have a file extent item
2115          *    pointing to an unwritten extent (and no data checksums as well).
2116          *
2117          * So trigger writeback for any eventual new dirty pages and then we
2118          * wait for all ordered extents to complete below.
2119          */
2120         ret = start_ordered_ops(inode, start, end);
2121         if (ret) {
2122                 inode_unlock(inode);
2123                 goto out;
2124         }
2125
2126         /*
2127          * We have to do this here to avoid the priority inversion of waiting on
2128          * IO of a lower priority task while holding a transaction open.
2129          */
2130         ret = btrfs_wait_ordered_range(inode, start, len);
2131         if (ret) {
2132                 up_write(&BTRFS_I(inode)->dio_sem);
2133                 inode_unlock(inode);
2134                 goto out;
2135         }
2136         atomic_inc(&root->log_batch);
2137
2138         smp_mb();
2139         if (btrfs_inode_in_log(BTRFS_I(inode), fs_info->generation) ||
2140             BTRFS_I(inode)->last_trans <= fs_info->last_trans_committed) {
2141                 /*
2142                  * We've had everything committed since the last time we were
2143                  * modified so clear this flag in case it was set for whatever
2144                  * reason, it's no longer relevant.
2145                  */
2146                 clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2147                           &BTRFS_I(inode)->runtime_flags);
2148                 /*
2149                  * An ordered extent might have started before and completed
2150                  * already with io errors, in which case the inode was not
2151                  * updated and we end up here. So check the inode's mapping
2152                  * for any errors that might have happened since we last
2153                  * checked called fsync.
2154                  */
2155                 ret = filemap_check_wb_err(inode->i_mapping, file->f_wb_err);
2156                 up_write(&BTRFS_I(inode)->dio_sem);
2157                 inode_unlock(inode);
2158                 goto out;
2159         }
2160
2161         /*
2162          * We use start here because we will need to wait on the IO to complete
2163          * in btrfs_sync_log, which could require joining a transaction (for
2164          * example checking cross references in the nocow path).  If we use join
2165          * here we could get into a situation where we're waiting on IO to
2166          * happen that is blocked on a transaction trying to commit.  With start
2167          * we inc the extwriter counter, so we wait for all extwriters to exit
2168          * before we start blocking joiners.  This comment is to keep somebody
2169          * from thinking they are super smart and changing this to
2170          * btrfs_join_transaction *cough*Josef*cough*.
2171          */
2172         trans = btrfs_start_transaction(root, 0);
2173         if (IS_ERR(trans)) {
2174                 ret = PTR_ERR(trans);
2175                 up_write(&BTRFS_I(inode)->dio_sem);
2176                 inode_unlock(inode);
2177                 goto out;
2178         }
2179
2180         ret = btrfs_log_dentry_safe(trans, dentry, start, end, &ctx);
2181         if (ret < 0) {
2182                 /* Fallthrough and commit/free transaction. */
2183                 ret = 1;
2184         }
2185
2186         /* we've logged all the items and now have a consistent
2187          * version of the file in the log.  It is possible that
2188          * someone will come in and modify the file, but that's
2189          * fine because the log is consistent on disk, and we
2190          * have references to all of the file's extents
2191          *
2192          * It is possible that someone will come in and log the
2193          * file again, but that will end up using the synchronization
2194          * inside btrfs_sync_log to keep things safe.
2195          */
2196         up_write(&BTRFS_I(inode)->dio_sem);
2197         inode_unlock(inode);
2198
2199         if (ret != BTRFS_NO_LOG_SYNC) {
2200                 if (!ret) {
2201                         ret = btrfs_sync_log(trans, root, &ctx);
2202                         if (!ret) {
2203                                 ret = btrfs_end_transaction(trans);
2204                                 goto out;
2205                         }
2206                 }
2207                 ret = btrfs_commit_transaction(trans);
2208         } else {
2209                 ret = btrfs_end_transaction(trans);
2210         }
2211 out:
2212         ASSERT(list_empty(&ctx.list));
2213         err = file_check_and_advance_wb_err(file);
2214         if (!ret)
2215                 ret = err;
2216         return ret > 0 ? -EIO : ret;
2217 }
2218
2219 static const struct vm_operations_struct btrfs_file_vm_ops = {
2220         .fault          = filemap_fault,
2221         .map_pages      = filemap_map_pages,
2222         .page_mkwrite   = btrfs_page_mkwrite,
2223 };
2224
2225 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
2226 {
2227         struct address_space *mapping = filp->f_mapping;
2228
2229         if (!mapping->a_ops->readpage)
2230                 return -ENOEXEC;
2231
2232         file_accessed(filp);
2233         vma->vm_ops = &btrfs_file_vm_ops;
2234
2235         return 0;
2236 }
2237
2238 static int hole_mergeable(struct btrfs_inode *inode, struct extent_buffer *leaf,
2239                           int slot, u64 start, u64 end)
2240 {
2241         struct btrfs_file_extent_item *fi;
2242         struct btrfs_key key;
2243
2244         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
2245                 return 0;
2246
2247         btrfs_item_key_to_cpu(leaf, &key, slot);
2248         if (key.objectid != btrfs_ino(inode) ||
2249             key.type != BTRFS_EXTENT_DATA_KEY)
2250                 return 0;
2251
2252         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
2253
2254         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
2255                 return 0;
2256
2257         if (btrfs_file_extent_disk_bytenr(leaf, fi))
2258                 return 0;
2259
2260         if (key.offset == end)
2261                 return 1;
2262         if (key.offset + btrfs_file_extent_num_bytes(leaf, fi) == start)
2263                 return 1;
2264         return 0;
2265 }
2266
2267 static int fill_holes(struct btrfs_trans_handle *trans,
2268                 struct btrfs_inode *inode,
2269                 struct btrfs_path *path, u64 offset, u64 end)
2270 {
2271         struct btrfs_fs_info *fs_info = trans->fs_info;
2272         struct btrfs_root *root = inode->root;
2273         struct extent_buffer *leaf;
2274         struct btrfs_file_extent_item *fi;
2275         struct extent_map *hole_em;
2276         struct extent_map_tree *em_tree = &inode->extent_tree;
2277         struct btrfs_key key;
2278         int ret;
2279
2280         if (btrfs_fs_incompat(fs_info, NO_HOLES))
2281                 goto out;
2282
2283         key.objectid = btrfs_ino(inode);
2284         key.type = BTRFS_EXTENT_DATA_KEY;
2285         key.offset = offset;
2286
2287         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
2288         if (ret <= 0) {
2289                 /*
2290                  * We should have dropped this offset, so if we find it then
2291                  * something has gone horribly wrong.
2292                  */
2293                 if (ret == 0)
2294                         ret = -EINVAL;
2295                 return ret;
2296         }
2297
2298         leaf = path->nodes[0];
2299         if (hole_mergeable(inode, leaf, path->slots[0] - 1, offset, end)) {
2300                 u64 num_bytes;
2301
2302                 path->slots[0]--;
2303                 fi = btrfs_item_ptr(leaf, path->slots[0],
2304                                     struct btrfs_file_extent_item);
2305                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) +
2306                         end - offset;
2307                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2308                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2309                 btrfs_set_file_extent_offset(leaf, fi, 0);
2310                 btrfs_mark_buffer_dirty(leaf);
2311                 goto out;
2312         }
2313
2314         if (hole_mergeable(inode, leaf, path->slots[0], offset, end)) {
2315                 u64 num_bytes;
2316
2317                 key.offset = offset;
2318                 btrfs_set_item_key_safe(fs_info, path, &key);
2319                 fi = btrfs_item_ptr(leaf, path->slots[0],
2320                                     struct btrfs_file_extent_item);
2321                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + end -
2322                         offset;
2323                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2324                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2325                 btrfs_set_file_extent_offset(leaf, fi, 0);
2326                 btrfs_mark_buffer_dirty(leaf);
2327                 goto out;
2328         }
2329         btrfs_release_path(path);
2330
2331         ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode),
2332                         offset, 0, 0, end - offset, 0, end - offset, 0, 0, 0);
2333         if (ret)
2334                 return ret;
2335
2336 out:
2337         btrfs_release_path(path);
2338
2339         hole_em = alloc_extent_map();
2340         if (!hole_em) {
2341                 btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2342                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
2343         } else {
2344                 hole_em->start = offset;
2345                 hole_em->len = end - offset;
2346                 hole_em->ram_bytes = hole_em->len;
2347                 hole_em->orig_start = offset;
2348
2349                 hole_em->block_start = EXTENT_MAP_HOLE;
2350                 hole_em->block_len = 0;
2351                 hole_em->orig_block_len = 0;
2352                 hole_em->bdev = fs_info->fs_devices->latest_bdev;
2353                 hole_em->compress_type = BTRFS_COMPRESS_NONE;
2354                 hole_em->generation = trans->transid;
2355
2356                 do {
2357                         btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2358                         write_lock(&em_tree->lock);
2359                         ret = add_extent_mapping(em_tree, hole_em, 1);
2360                         write_unlock(&em_tree->lock);
2361                 } while (ret == -EEXIST);
2362                 free_extent_map(hole_em);
2363                 if (ret)
2364                         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2365                                         &inode->runtime_flags);
2366         }
2367
2368         return 0;
2369 }
2370
2371 /*
2372  * Find a hole extent on given inode and change start/len to the end of hole
2373  * extent.(hole/vacuum extent whose em->start <= start &&
2374  *         em->start + em->len > start)
2375  * When a hole extent is found, return 1 and modify start/len.
2376  */
2377 static int find_first_non_hole(struct inode *inode, u64 *start, u64 *len)
2378 {
2379         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2380         struct extent_map *em;
2381         int ret = 0;
2382
2383         em = btrfs_get_extent(BTRFS_I(inode), NULL, 0,
2384                               round_down(*start, fs_info->sectorsize),
2385                               round_up(*len, fs_info->sectorsize), 0);
2386         if (IS_ERR(em))
2387                 return PTR_ERR(em);
2388
2389         /* Hole or vacuum extent(only exists in no-hole mode) */
2390         if (em->block_start == EXTENT_MAP_HOLE) {
2391                 ret = 1;
2392                 *len = em->start + em->len > *start + *len ?
2393                        0 : *start + *len - em->start - em->len;
2394                 *start = em->start + em->len;
2395         }
2396         free_extent_map(em);
2397         return ret;
2398 }
2399
2400 static int btrfs_punch_hole_lock_range(struct inode *inode,
2401                                        const u64 lockstart,
2402                                        const u64 lockend,
2403                                        struct extent_state **cached_state)
2404 {
2405         while (1) {
2406                 struct btrfs_ordered_extent *ordered;
2407                 int ret;
2408
2409                 truncate_pagecache_range(inode, lockstart, lockend);
2410
2411                 lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2412                                  cached_state);
2413                 ordered = btrfs_lookup_first_ordered_extent(inode, lockend);
2414
2415                 /*
2416                  * We need to make sure we have no ordered extents in this range
2417                  * and nobody raced in and read a page in this range, if we did
2418                  * we need to try again.
2419                  */
2420                 if ((!ordered ||
2421                     (ordered->file_offset + ordered->len <= lockstart ||
2422                      ordered->file_offset > lockend)) &&
2423                      !filemap_range_has_page(inode->i_mapping,
2424                                              lockstart, lockend)) {
2425                         if (ordered)
2426                                 btrfs_put_ordered_extent(ordered);
2427                         break;
2428                 }
2429                 if (ordered)
2430                         btrfs_put_ordered_extent(ordered);
2431                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
2432                                      lockend, cached_state);
2433                 ret = btrfs_wait_ordered_range(inode, lockstart,
2434                                                lockend - lockstart + 1);
2435                 if (ret)
2436                         return ret;
2437         }
2438         return 0;
2439 }
2440
2441 static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
2442 {
2443         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2444         struct btrfs_root *root = BTRFS_I(inode)->root;
2445         struct extent_state *cached_state = NULL;
2446         struct btrfs_path *path;
2447         struct btrfs_block_rsv *rsv;
2448         struct btrfs_trans_handle *trans;
2449         u64 lockstart;
2450         u64 lockend;
2451         u64 tail_start;
2452         u64 tail_len;
2453         u64 orig_start = offset;
2454         u64 cur_offset;
2455         u64 min_size = btrfs_calc_trans_metadata_size(fs_info, 1);
2456         u64 drop_end;
2457         int ret = 0;
2458         int err = 0;
2459         unsigned int rsv_count;
2460         bool same_block;
2461         bool no_holes = btrfs_fs_incompat(fs_info, NO_HOLES);
2462         u64 ino_size;
2463         bool truncated_block = false;
2464         bool updated_inode = false;
2465
2466         ret = btrfs_wait_ordered_range(inode, offset, len);
2467         if (ret)
2468                 return ret;
2469
2470         inode_lock(inode);
2471         ino_size = round_up(inode->i_size, fs_info->sectorsize);
2472         ret = find_first_non_hole(inode, &offset, &len);
2473         if (ret < 0)
2474                 goto out_only_mutex;
2475         if (ret && !len) {
2476                 /* Already in a large hole */
2477                 ret = 0;
2478                 goto out_only_mutex;
2479         }
2480
2481         lockstart = round_up(offset, btrfs_inode_sectorsize(inode));
2482         lockend = round_down(offset + len,
2483                              btrfs_inode_sectorsize(inode)) - 1;
2484         same_block = (BTRFS_BYTES_TO_BLKS(fs_info, offset))
2485                 == (BTRFS_BYTES_TO_BLKS(fs_info, offset + len - 1));
2486         /*
2487          * We needn't truncate any block which is beyond the end of the file
2488          * because we are sure there is no data there.
2489          */
2490         /*
2491          * Only do this if we are in the same block and we aren't doing the
2492          * entire block.
2493          */
2494         if (same_block && len < fs_info->sectorsize) {
2495                 if (offset < ino_size) {
2496                         truncated_block = true;
2497                         ret = btrfs_truncate_block(inode, offset, len, 0);
2498                 } else {
2499                         ret = 0;
2500                 }
2501                 goto out_only_mutex;
2502         }
2503
2504         /* zero back part of the first block */
2505         if (offset < ino_size) {
2506                 truncated_block = true;
2507                 ret = btrfs_truncate_block(inode, offset, 0, 0);
2508                 if (ret) {
2509                         inode_unlock(inode);
2510                         return ret;
2511                 }
2512         }
2513
2514         /* Check the aligned pages after the first unaligned page,
2515          * if offset != orig_start, which means the first unaligned page
2516          * including several following pages are already in holes,
2517          * the extra check can be skipped */
2518         if (offset == orig_start) {
2519                 /* after truncate page, check hole again */
2520                 len = offset + len - lockstart;
2521                 offset = lockstart;
2522                 ret = find_first_non_hole(inode, &offset, &len);
2523                 if (ret < 0)
2524                         goto out_only_mutex;
2525                 if (ret && !len) {
2526                         ret = 0;
2527                         goto out_only_mutex;
2528                 }
2529                 lockstart = offset;
2530         }
2531
2532         /* Check the tail unaligned part is in a hole */
2533         tail_start = lockend + 1;
2534         tail_len = offset + len - tail_start;
2535         if (tail_len) {
2536                 ret = find_first_non_hole(inode, &tail_start, &tail_len);
2537                 if (unlikely(ret < 0))
2538                         goto out_only_mutex;
2539                 if (!ret) {
2540                         /* zero the front end of the last page */
2541                         if (tail_start + tail_len < ino_size) {
2542                                 truncated_block = true;
2543                                 ret = btrfs_truncate_block(inode,
2544                                                         tail_start + tail_len,
2545                                                         0, 1);
2546                                 if (ret)
2547                                         goto out_only_mutex;
2548                         }
2549                 }
2550         }
2551
2552         if (lockend < lockstart) {
2553                 ret = 0;
2554                 goto out_only_mutex;
2555         }
2556
2557         ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
2558                                           &cached_state);
2559         if (ret)
2560                 goto out_only_mutex;
2561
2562         path = btrfs_alloc_path();
2563         if (!path) {
2564                 ret = -ENOMEM;
2565                 goto out;
2566         }
2567
2568         rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
2569         if (!rsv) {
2570                 ret = -ENOMEM;
2571                 goto out_free;
2572         }
2573         rsv->size = btrfs_calc_trans_metadata_size(fs_info, 1);
2574         rsv->failfast = 1;
2575
2576         /*
2577          * 1 - update the inode
2578          * 1 - removing the extents in the range
2579          * 1 - adding the hole extent if no_holes isn't set
2580          */
2581         rsv_count = no_holes ? 2 : 3;
2582         trans = btrfs_start_transaction(root, rsv_count);
2583         if (IS_ERR(trans)) {
2584                 err = PTR_ERR(trans);
2585                 goto out_free;
2586         }
2587
2588         ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
2589                                       min_size, false);
2590         BUG_ON(ret);
2591         trans->block_rsv = rsv;
2592
2593         cur_offset = lockstart;
2594         len = lockend - cur_offset;
2595         while (cur_offset < lockend) {
2596                 ret = __btrfs_drop_extents(trans, root, inode, path,
2597                                            cur_offset, lockend + 1,
2598                                            &drop_end, 1, 0, 0, NULL);
2599                 if (ret != -ENOSPC)
2600                         break;
2601
2602                 trans->block_rsv = &fs_info->trans_block_rsv;
2603
2604                 if (cur_offset < drop_end && cur_offset < ino_size) {
2605                         ret = fill_holes(trans, BTRFS_I(inode), path,
2606                                         cur_offset, drop_end);
2607                         if (ret) {
2608                                 /*
2609                                  * If we failed then we didn't insert our hole
2610                                  * entries for the area we dropped, so now the
2611                                  * fs is corrupted, so we must abort the
2612                                  * transaction.
2613                                  */
2614                                 btrfs_abort_transaction(trans, ret);
2615                                 err = ret;
2616                                 break;
2617                         }
2618                 }
2619
2620                 cur_offset = drop_end;
2621
2622                 ret = btrfs_update_inode(trans, root, inode);
2623                 if (ret) {
2624                         err = ret;
2625                         break;
2626                 }
2627
2628                 btrfs_end_transaction(trans);
2629                 btrfs_btree_balance_dirty(fs_info);
2630
2631                 trans = btrfs_start_transaction(root, rsv_count);
2632                 if (IS_ERR(trans)) {
2633                         ret = PTR_ERR(trans);
2634                         trans = NULL;
2635                         break;
2636                 }
2637
2638                 ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
2639                                               rsv, min_size, false);
2640                 BUG_ON(ret);    /* shouldn't happen */
2641                 trans->block_rsv = rsv;
2642
2643                 ret = find_first_non_hole(inode, &cur_offset, &len);
2644                 if (unlikely(ret < 0))
2645                         break;
2646                 if (ret && !len) {
2647                         ret = 0;
2648                         break;
2649                 }
2650         }
2651
2652         if (ret) {
2653                 err = ret;
2654                 goto out_trans;
2655         }
2656
2657         trans->block_rsv = &fs_info->trans_block_rsv;
2658         /*
2659          * If we are using the NO_HOLES feature we might have had already an
2660          * hole that overlaps a part of the region [lockstart, lockend] and
2661          * ends at (or beyond) lockend. Since we have no file extent items to
2662          * represent holes, drop_end can be less than lockend and so we must
2663          * make sure we have an extent map representing the existing hole (the
2664          * call to __btrfs_drop_extents() might have dropped the existing extent
2665          * map representing the existing hole), otherwise the fast fsync path
2666          * will not record the existence of the hole region
2667          * [existing_hole_start, lockend].
2668          */
2669         if (drop_end <= lockend)
2670                 drop_end = lockend + 1;
2671         /*
2672          * Don't insert file hole extent item if it's for a range beyond eof
2673          * (because it's useless) or if it represents a 0 bytes range (when
2674          * cur_offset == drop_end).
2675          */
2676         if (cur_offset < ino_size && cur_offset < drop_end) {
2677                 ret = fill_holes(trans, BTRFS_I(inode), path,
2678                                 cur_offset, drop_end);
2679                 if (ret) {
2680                         /* Same comment as above. */
2681                         btrfs_abort_transaction(trans, ret);
2682                         err = ret;
2683                         goto out_trans;
2684                 }
2685         }
2686
2687 out_trans:
2688         if (!trans)
2689                 goto out_free;
2690
2691         inode_inc_iversion(inode);
2692         inode->i_mtime = inode->i_ctime = current_time(inode);
2693
2694         trans->block_rsv = &fs_info->trans_block_rsv;
2695         ret = btrfs_update_inode(trans, root, inode);
2696         updated_inode = true;
2697         btrfs_end_transaction(trans);
2698         btrfs_btree_balance_dirty(fs_info);
2699 out_free:
2700         btrfs_free_path(path);
2701         btrfs_free_block_rsv(fs_info, rsv);
2702 out:
2703         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2704                              &cached_state);
2705 out_only_mutex:
2706         if (!updated_inode && truncated_block && !ret && !err) {
2707                 /*
2708                  * If we only end up zeroing part of a page, we still need to
2709                  * update the inode item, so that all the time fields are
2710                  * updated as well as the necessary btrfs inode in memory fields
2711                  * for detecting, at fsync time, if the inode isn't yet in the
2712                  * log tree or it's there but not up to date.
2713                  */
2714                 trans = btrfs_start_transaction(root, 1);
2715                 if (IS_ERR(trans)) {
2716                         err = PTR_ERR(trans);
2717                 } else {
2718                         err = btrfs_update_inode(trans, root, inode);
2719                         ret = btrfs_end_transaction(trans);
2720                 }
2721         }
2722         inode_unlock(inode);
2723         if (ret && !err)
2724                 err = ret;
2725         return err;
2726 }
2727
2728 /* Helper structure to record which range is already reserved */
2729 struct falloc_range {
2730         struct list_head list;
2731         u64 start;
2732         u64 len;
2733 };
2734
2735 /*
2736  * Helper function to add falloc range
2737  *
2738  * Caller should have locked the larger range of extent containing
2739  * [start, len)
2740  */
2741 static int add_falloc_range(struct list_head *head, u64 start, u64 len)
2742 {
2743         struct falloc_range *prev = NULL;
2744         struct falloc_range *range = NULL;
2745
2746         if (list_empty(head))
2747                 goto insert;
2748
2749         /*
2750          * As fallocate iterate by bytenr order, we only need to check
2751          * the last range.
2752          */
2753         prev = list_entry(head->prev, struct falloc_range, list);
2754         if (prev->start + prev->len == start) {
2755                 prev->len += len;
2756                 return 0;
2757         }
2758 insert:
2759         range = kmalloc(sizeof(*range), GFP_KERNEL);
2760         if (!range)
2761                 return -ENOMEM;
2762         range->start = start;
2763         range->len = len;
2764         list_add_tail(&range->list, head);
2765         return 0;
2766 }
2767
2768 static int btrfs_fallocate_update_isize(struct inode *inode,
2769                                         const u64 end,
2770                                         const int mode)
2771 {
2772         struct btrfs_trans_handle *trans;
2773         struct btrfs_root *root = BTRFS_I(inode)->root;
2774         int ret;
2775         int ret2;
2776
2777         if (mode & FALLOC_FL_KEEP_SIZE || end <= i_size_read(inode))
2778                 return 0;
2779
2780         trans = btrfs_start_transaction(root, 1);
2781         if (IS_ERR(trans))
2782                 return PTR_ERR(trans);
2783
2784         inode->i_ctime = current_time(inode);
2785         i_size_write(inode, end);
2786         btrfs_ordered_update_i_size(inode, end, NULL);
2787         ret = btrfs_update_inode(trans, root, inode);
2788         ret2 = btrfs_end_transaction(trans);
2789
2790         return ret ? ret : ret2;
2791 }
2792
2793 enum {
2794         RANGE_BOUNDARY_WRITTEN_EXTENT = 0,
2795         RANGE_BOUNDARY_PREALLOC_EXTENT = 1,
2796         RANGE_BOUNDARY_HOLE = 2,
2797 };
2798
2799 static int btrfs_zero_range_check_range_boundary(struct inode *inode,
2800                                                  u64 offset)
2801 {
2802         const u64 sectorsize = btrfs_inode_sectorsize(inode);
2803         struct extent_map *em;
2804         int ret;
2805
2806         offset = round_down(offset, sectorsize);
2807         em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, offset, sectorsize, 0);
2808         if (IS_ERR(em))
2809                 return PTR_ERR(em);
2810
2811         if (em->block_start == EXTENT_MAP_HOLE)
2812                 ret = RANGE_BOUNDARY_HOLE;
2813         else if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
2814                 ret = RANGE_BOUNDARY_PREALLOC_EXTENT;
2815         else
2816                 ret = RANGE_BOUNDARY_WRITTEN_EXTENT;
2817
2818         free_extent_map(em);
2819         return ret;
2820 }
2821
2822 static int btrfs_zero_range(struct inode *inode,
2823                             loff_t offset,
2824                             loff_t len,
2825                             const int mode)
2826 {
2827         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2828         struct extent_map *em;
2829         struct extent_changeset *data_reserved = NULL;
2830         int ret;
2831         u64 alloc_hint = 0;
2832         const u64 sectorsize = btrfs_inode_sectorsize(inode);
2833         u64 alloc_start = round_down(offset, sectorsize);
2834         u64 alloc_end = round_up(offset + len, sectorsize);
2835         u64 bytes_to_reserve = 0;
2836         bool space_reserved = false;
2837
2838         inode_dio_wait(inode);
2839
2840         em = btrfs_get_extent(BTRFS_I(inode), NULL, 0,
2841                               alloc_start, alloc_end - alloc_start, 0);
2842         if (IS_ERR(em)) {
2843                 ret = PTR_ERR(em);
2844                 goto out;
2845         }
2846
2847         /*
2848          * Avoid hole punching and extent allocation for some cases. More cases
2849          * could be considered, but these are unlikely common and we keep things
2850          * as simple as possible for now. Also, intentionally, if the target
2851          * range contains one or more prealloc extents together with regular
2852          * extents and holes, we drop all the existing extents and allocate a
2853          * new prealloc extent, so that we get a larger contiguous disk extent.
2854          */
2855         if (em->start <= alloc_start &&
2856             test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
2857                 const u64 em_end = em->start + em->len;
2858
2859                 if (em_end >= offset + len) {
2860                         /*
2861                          * The whole range is already a prealloc extent,
2862                          * do nothing except updating the inode's i_size if
2863                          * needed.
2864                          */
2865                         free_extent_map(em);
2866                         ret = btrfs_fallocate_update_isize(inode, offset + len,
2867                                                            mode);
2868                         goto out;
2869                 }
2870                 /*
2871                  * Part of the range is already a prealloc extent, so operate
2872                  * only on the remaining part of the range.
2873                  */
2874                 alloc_start = em_end;
2875                 ASSERT(IS_ALIGNED(alloc_start, sectorsize));
2876                 len = offset + len - alloc_start;
2877                 offset = alloc_start;
2878                 alloc_hint = em->block_start + em->len;
2879         }
2880         free_extent_map(em);
2881
2882         if (BTRFS_BYTES_TO_BLKS(fs_info, offset) ==
2883             BTRFS_BYTES_TO_BLKS(fs_info, offset + len - 1)) {
2884                 em = btrfs_get_extent(BTRFS_I(inode), NULL, 0,
2885                                       alloc_start, sectorsize, 0);
2886                 if (IS_ERR(em)) {
2887                         ret = PTR_ERR(em);
2888                         goto out;
2889                 }
2890
2891                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
2892                         free_extent_map(em);
2893                         ret = btrfs_fallocate_update_isize(inode, offset + len,
2894                                                            mode);
2895                         goto out;
2896                 }
2897                 if (len < sectorsize && em->block_start != EXTENT_MAP_HOLE) {
2898                         free_extent_map(em);
2899                         ret = btrfs_truncate_block(inode, offset, len, 0);
2900                         if (!ret)
2901                                 ret = btrfs_fallocate_update_isize(inode,
2902                                                                    offset + len,
2903                                                                    mode);
2904                         return ret;
2905                 }
2906                 free_extent_map(em);
2907                 alloc_start = round_down(offset, sectorsize);
2908                 alloc_end = alloc_start + sectorsize;
2909                 goto reserve_space;
2910         }
2911
2912         alloc_start = round_up(offset, sectorsize);
2913         alloc_end = round_down(offset + len, sectorsize);
2914
2915         /*
2916          * For unaligned ranges, check the pages at the boundaries, they might
2917          * map to an extent, in which case we need to partially zero them, or
2918          * they might map to a hole, in which case we need our allocation range
2919          * to cover them.
2920          */
2921         if (!IS_ALIGNED(offset, sectorsize)) {
2922                 ret = btrfs_zero_range_check_range_boundary(inode, offset);
2923                 if (ret < 0)
2924                         goto out;
2925                 if (ret == RANGE_BOUNDARY_HOLE) {
2926                         alloc_start = round_down(offset, sectorsize);
2927                         ret = 0;
2928                 } else if (ret == RANGE_BOUNDARY_WRITTEN_EXTENT) {
2929                         ret = btrfs_truncate_block(inode, offset, 0, 0);
2930                         if (ret)
2931                                 goto out;
2932                 } else {
2933                         ret = 0;
2934                 }
2935         }
2936
2937         if (!IS_ALIGNED(offset + len, sectorsize)) {
2938                 ret = btrfs_zero_range_check_range_boundary(inode,
2939                                                             offset + len);
2940                 if (ret < 0)
2941                         goto out;
2942                 if (ret == RANGE_BOUNDARY_HOLE) {
2943                         alloc_end = round_up(offset + len, sectorsize);
2944                         ret = 0;
2945                 } else if (ret == RANGE_BOUNDARY_WRITTEN_EXTENT) {
2946                         ret = btrfs_truncate_block(inode, offset + len, 0, 1);
2947                         if (ret)
2948                                 goto out;
2949                 } else {
2950                         ret = 0;
2951                 }
2952         }
2953
2954 reserve_space:
2955         if (alloc_start < alloc_end) {
2956                 struct extent_state *cached_state = NULL;
2957                 const u64 lockstart = alloc_start;
2958                 const u64 lockend = alloc_end - 1;
2959
2960                 bytes_to_reserve = alloc_end - alloc_start;
2961                 ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
2962                                                       bytes_to_reserve);
2963                 if (ret < 0)
2964                         goto out;
2965                 space_reserved = true;
2966                 ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
2967                                                 alloc_start, bytes_to_reserve);
2968                 if (ret)
2969                         goto out;
2970                 ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
2971                                                   &cached_state);
2972                 if (ret)
2973                         goto out;
2974                 ret = btrfs_prealloc_file_range(inode, mode, alloc_start,
2975                                                 alloc_end - alloc_start,
2976                                                 i_blocksize(inode),
2977                                                 offset + len, &alloc_hint);
2978                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
2979                                      lockend, &cached_state);
2980                 /* btrfs_prealloc_file_range releases reserved space on error */
2981                 if (ret) {
2982                         space_reserved = false;
2983                         goto out;
2984                 }
2985         }
2986         ret = btrfs_fallocate_update_isize(inode, offset + len, mode);
2987  out:
2988         if (ret && space_reserved)
2989                 btrfs_free_reserved_data_space(inode, data_reserved,
2990                                                alloc_start, bytes_to_reserve);
2991         extent_changeset_free(data_reserved);
2992
2993         return ret;
2994 }
2995
2996 static long btrfs_fallocate(struct file *file, int mode,
2997                             loff_t offset, loff_t len)
2998 {
2999         struct inode *inode = file_inode(file);
3000         struct extent_state *cached_state = NULL;
3001         struct extent_changeset *data_reserved = NULL;
3002         struct falloc_range *range;
3003         struct falloc_range *tmp;
3004         struct list_head reserve_list;
3005         u64 cur_offset;
3006         u64 last_byte;
3007         u64 alloc_start;
3008         u64 alloc_end;
3009         u64 alloc_hint = 0;
3010         u64 locked_end;
3011         u64 actual_end = 0;
3012         struct extent_map *em;
3013         int blocksize = btrfs_inode_sectorsize(inode);
3014         int ret;
3015
3016         alloc_start = round_down(offset, blocksize);
3017         alloc_end = round_up(offset + len, blocksize);
3018         cur_offset = alloc_start;
3019
3020         /* Make sure we aren't being give some crap mode */
3021         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
3022                      FALLOC_FL_ZERO_RANGE))
3023                 return -EOPNOTSUPP;
3024
3025         if (mode & FALLOC_FL_PUNCH_HOLE)
3026                 return btrfs_punch_hole(inode, offset, len);
3027
3028         /*
3029          * Only trigger disk allocation, don't trigger qgroup reserve
3030          *
3031          * For qgroup space, it will be checked later.
3032          */
3033         if (!(mode & FALLOC_FL_ZERO_RANGE)) {
3034                 ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
3035                                                       alloc_end - alloc_start);
3036                 if (ret < 0)
3037                         return ret;
3038         }
3039
3040         inode_lock(inode);
3041
3042         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) {
3043                 ret = inode_newsize_ok(inode, offset + len);
3044                 if (ret)
3045                         goto out;
3046         }
3047
3048         /*
3049          * TODO: Move these two operations after we have checked
3050          * accurate reserved space, or fallocate can still fail but
3051          * with page truncated or size expanded.
3052          *
3053          * But that's a minor problem and won't do much harm BTW.
3054          */
3055         if (alloc_start > inode->i_size) {
3056                 ret = btrfs_cont_expand(inode, i_size_read(inode),
3057                                         alloc_start);
3058                 if (ret)
3059                         goto out;
3060         } else if (offset + len > inode->i_size) {
3061                 /*
3062                  * If we are fallocating from the end of the file onward we
3063                  * need to zero out the end of the block if i_size lands in the
3064                  * middle of a block.
3065                  */
3066                 ret = btrfs_truncate_block(inode, inode->i_size, 0, 0);
3067                 if (ret)
3068                         goto out;
3069         }
3070
3071         /*
3072          * wait for ordered IO before we have any locks.  We'll loop again
3073          * below with the locks held.
3074          */
3075         ret = btrfs_wait_ordered_range(inode, alloc_start,
3076                                        alloc_end - alloc_start);
3077         if (ret)
3078                 goto out;
3079
3080         if (mode & FALLOC_FL_ZERO_RANGE) {
3081                 ret = btrfs_zero_range(inode, offset, len, mode);
3082                 inode_unlock(inode);
3083                 return ret;
3084         }
3085
3086         locked_end = alloc_end - 1;
3087         while (1) {
3088                 struct btrfs_ordered_extent *ordered;
3089
3090                 /* the extent lock is ordered inside the running
3091                  * transaction
3092                  */
3093                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
3094                                  locked_end, &cached_state);
3095                 ordered = btrfs_lookup_first_ordered_extent(inode, locked_end);
3096
3097                 if (ordered &&
3098                     ordered->file_offset + ordered->len > alloc_start &&
3099                     ordered->file_offset < alloc_end) {
3100                         btrfs_put_ordered_extent(ordered);
3101                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
3102                                              alloc_start, locked_end,
3103                                              &cached_state);
3104                         /*
3105                          * we can't wait on the range with the transaction
3106                          * running or with the extent lock held
3107                          */
3108                         ret = btrfs_wait_ordered_range(inode, alloc_start,
3109                                                        alloc_end - alloc_start);
3110                         if (ret)
3111                                 goto out;
3112                 } else {
3113                         if (ordered)
3114                                 btrfs_put_ordered_extent(ordered);
3115                         break;
3116                 }
3117         }
3118
3119         /* First, check if we exceed the qgroup limit */
3120         INIT_LIST_HEAD(&reserve_list);
3121         while (cur_offset < alloc_end) {
3122                 em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, cur_offset,
3123                                       alloc_end - cur_offset, 0);
3124                 if (IS_ERR(em)) {
3125                         ret = PTR_ERR(em);
3126                         break;
3127                 }
3128                 last_byte = min(extent_map_end(em), alloc_end);
3129                 actual_end = min_t(u64, extent_map_end(em), offset + len);
3130                 last_byte = ALIGN(last_byte, blocksize);
3131                 if (em->block_start == EXTENT_MAP_HOLE ||
3132                     (cur_offset >= inode->i_size &&
3133                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
3134                         ret = add_falloc_range(&reserve_list, cur_offset,
3135                                                last_byte - cur_offset);
3136                         if (ret < 0) {
3137                                 free_extent_map(em);
3138                                 break;
3139                         }
3140                         ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
3141                                         cur_offset, last_byte - cur_offset);
3142                         if (ret < 0) {
3143                                 cur_offset = last_byte;
3144                                 free_extent_map(em);
3145                                 break;
3146                         }
3147                 } else {
3148                         /*
3149                          * Do not need to reserve unwritten extent for this
3150                          * range, free reserved data space first, otherwise
3151                          * it'll result in false ENOSPC error.
3152                          */
3153                         btrfs_free_reserved_data_space(inode, data_reserved,
3154                                         cur_offset, last_byte - cur_offset);
3155                 }
3156                 free_extent_map(em);
3157                 cur_offset = last_byte;
3158         }
3159
3160         /*
3161          * If ret is still 0, means we're OK to fallocate.
3162          * Or just cleanup the list and exit.
3163          */
3164         list_for_each_entry_safe(range, tmp, &reserve_list, list) {
3165                 if (!ret)
3166                         ret = btrfs_prealloc_file_range(inode, mode,
3167                                         range->start,
3168                                         range->len, i_blocksize(inode),
3169                                         offset + len, &alloc_hint);
3170                 else
3171                         btrfs_free_reserved_data_space(inode,
3172                                         data_reserved, range->start,
3173                                         range->len);
3174                 list_del(&range->list);
3175                 kfree(range);
3176         }
3177         if (ret < 0)
3178                 goto out_unlock;
3179
3180         /*
3181          * We didn't need to allocate any more space, but we still extended the
3182          * size of the file so we need to update i_size and the inode item.
3183          */
3184         ret = btrfs_fallocate_update_isize(inode, actual_end, mode);
3185 out_unlock:
3186         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
3187                              &cached_state);
3188 out:
3189         inode_unlock(inode);
3190         /* Let go of our reservation. */
3191         if (ret != 0 && !(mode & FALLOC_FL_ZERO_RANGE))
3192                 btrfs_free_reserved_data_space(inode, data_reserved,
3193                                 cur_offset, alloc_end - cur_offset);
3194         extent_changeset_free(data_reserved);
3195         return ret;
3196 }
3197
3198 static int find_desired_extent(struct inode *inode, loff_t *offset, int whence)
3199 {
3200         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3201         struct extent_map *em = NULL;
3202         struct extent_state *cached_state = NULL;
3203         u64 lockstart;
3204         u64 lockend;
3205         u64 start;
3206         u64 len;
3207         int ret = 0;
3208
3209         if (inode->i_size == 0)
3210                 return -ENXIO;
3211
3212         /*
3213          * *offset can be negative, in this case we start finding DATA/HOLE from
3214          * the very start of the file.
3215          */
3216         start = max_t(loff_t, 0, *offset);
3217
3218         lockstart = round_down(start, fs_info->sectorsize);
3219         lockend = round_up(i_size_read(inode),
3220                            fs_info->sectorsize);
3221         if (lockend <= lockstart)
3222                 lockend = lockstart + fs_info->sectorsize;
3223         lockend--;
3224         len = lockend - lockstart + 1;
3225
3226         lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
3227                          &cached_state);
3228
3229         while (start < inode->i_size) {
3230                 em = btrfs_get_extent_fiemap(BTRFS_I(inode), start, len);
3231                 if (IS_ERR(em)) {
3232                         ret = PTR_ERR(em);
3233                         em = NULL;
3234                         break;
3235                 }
3236
3237                 if (whence == SEEK_HOLE &&
3238                     (em->block_start == EXTENT_MAP_HOLE ||
3239                      test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
3240                         break;
3241                 else if (whence == SEEK_DATA &&
3242                            (em->block_start != EXTENT_MAP_HOLE &&
3243                             !test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
3244                         break;
3245
3246                 start = em->start + em->len;
3247                 free_extent_map(em);
3248                 em = NULL;
3249                 cond_resched();
3250         }
3251         free_extent_map(em);
3252         if (!ret) {
3253                 if (whence == SEEK_DATA && start >= inode->i_size)
3254                         ret = -ENXIO;
3255                 else
3256                         *offset = min_t(loff_t, start, inode->i_size);
3257         }
3258         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
3259                              &cached_state);
3260         return ret;
3261 }
3262
3263 static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
3264 {
3265         struct inode *inode = file->f_mapping->host;
3266         int ret;
3267
3268         inode_lock(inode);
3269         switch (whence) {
3270         case SEEK_END:
3271         case SEEK_CUR:
3272                 offset = generic_file_llseek(file, offset, whence);
3273                 goto out;
3274         case SEEK_DATA:
3275         case SEEK_HOLE:
3276                 if (offset >= i_size_read(inode)) {
3277                         inode_unlock(inode);
3278                         return -ENXIO;
3279                 }
3280
3281                 ret = find_desired_extent(inode, &offset, whence);
3282                 if (ret) {
3283                         inode_unlock(inode);
3284                         return ret;
3285                 }
3286         }
3287
3288         offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
3289 out:
3290         inode_unlock(inode);
3291         return offset;
3292 }
3293
3294 static int btrfs_file_open(struct inode *inode, struct file *filp)
3295 {
3296         filp->f_mode |= FMODE_NOWAIT;
3297         return generic_file_open(inode, filp);
3298 }
3299
3300 const struct file_operations btrfs_file_operations = {
3301         .llseek         = btrfs_file_llseek,
3302         .read_iter      = generic_file_read_iter,
3303         .splice_read    = generic_file_splice_read,
3304         .write_iter     = btrfs_file_write_iter,
3305         .mmap           = btrfs_file_mmap,
3306         .open           = btrfs_file_open,
3307         .release        = btrfs_release_file,
3308         .fsync          = btrfs_sync_file,
3309         .fallocate      = btrfs_fallocate,
3310         .unlocked_ioctl = btrfs_ioctl,
3311 #ifdef CONFIG_COMPAT
3312         .compat_ioctl   = btrfs_compat_ioctl,
3313 #endif
3314         .remap_file_range = btrfs_remap_file_range,
3315 };
3316
3317 void __cold btrfs_auto_defrag_exit(void)
3318 {
3319         kmem_cache_destroy(btrfs_inode_defrag_cachep);
3320 }
3321
3322 int __init btrfs_auto_defrag_init(void)
3323 {
3324         btrfs_inode_defrag_cachep = kmem_cache_create("btrfs_inode_defrag",
3325                                         sizeof(struct inode_defrag), 0,
3326                                         SLAB_MEM_SPREAD,
3327                                         NULL);
3328         if (!btrfs_inode_defrag_cachep)
3329                 return -ENOMEM;
3330
3331         return 0;
3332 }
3333
3334 int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end)
3335 {
3336         int ret;
3337
3338         /*
3339          * So with compression we will find and lock a dirty page and clear the
3340          * first one as dirty, setup an async extent, and immediately return
3341          * with the entire range locked but with nobody actually marked with
3342          * writeback.  So we can't just filemap_write_and_wait_range() and
3343          * expect it to work since it will just kick off a thread to do the
3344          * actual work.  So we need to call filemap_fdatawrite_range _again_
3345          * since it will wait on the page lock, which won't be unlocked until
3346          * after the pages have been marked as writeback and so we're good to go
3347          * from there.  We have to do this otherwise we'll miss the ordered
3348          * extents and that results in badness.  Please Josef, do not think you
3349          * know better and pull this out at some point in the future, it is
3350          * right and you are wrong.
3351          */
3352         ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
3353         if (!ret && test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
3354                              &BTRFS_I(inode)->runtime_flags))
3355                 ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
3356
3357         return ret;
3358 }