Loading...
1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/err.h>
4#include <linux/slab.h>
5#include <linux/spinlock.h>
6#include "messages.h"
7#include "ctree.h"
8#include "volumes.h"
9#include "extent_map.h"
10#include "compression.h"
11#include "btrfs_inode.h"
12
13
14static struct kmem_cache *extent_map_cache;
15
16int __init extent_map_init(void)
17{
18 extent_map_cache = kmem_cache_create("btrfs_extent_map",
19 sizeof(struct extent_map), 0,
20 SLAB_MEM_SPREAD, NULL);
21 if (!extent_map_cache)
22 return -ENOMEM;
23 return 0;
24}
25
26void __cold extent_map_exit(void)
27{
28 kmem_cache_destroy(extent_map_cache);
29}
30
31/*
32 * Initialize the extent tree @tree. Should be called for each new inode or
33 * other user of the extent_map interface.
34 */
35void extent_map_tree_init(struct extent_map_tree *tree)
36{
37 tree->map = RB_ROOT_CACHED;
38 INIT_LIST_HEAD(&tree->modified_extents);
39 rwlock_init(&tree->lock);
40}
41
42/*
43 * Allocate a new extent_map structure. The new structure is returned with a
44 * reference count of one and needs to be freed using free_extent_map()
45 */
46struct extent_map *alloc_extent_map(void)
47{
48 struct extent_map *em;
49 em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
50 if (!em)
51 return NULL;
52 RB_CLEAR_NODE(&em->rb_node);
53 refcount_set(&em->refs, 1);
54 INIT_LIST_HEAD(&em->list);
55 return em;
56}
57
58/*
59 * Drop the reference out on @em by one and free the structure if the reference
60 * count hits zero.
61 */
62void free_extent_map(struct extent_map *em)
63{
64 if (!em)
65 return;
66 if (refcount_dec_and_test(&em->refs)) {
67 WARN_ON(extent_map_in_tree(em));
68 WARN_ON(!list_empty(&em->list));
69 kmem_cache_free(extent_map_cache, em);
70 }
71}
72
73/* Do the math around the end of an extent, handling wrapping. */
74static u64 range_end(u64 start, u64 len)
75{
76 if (start + len < start)
77 return (u64)-1;
78 return start + len;
79}
80
81static int tree_insert(struct rb_root_cached *root, struct extent_map *em)
82{
83 struct rb_node **p = &root->rb_root.rb_node;
84 struct rb_node *parent = NULL;
85 struct extent_map *entry = NULL;
86 struct rb_node *orig_parent = NULL;
87 u64 end = range_end(em->start, em->len);
88 bool leftmost = true;
89
90 while (*p) {
91 parent = *p;
92 entry = rb_entry(parent, struct extent_map, rb_node);
93
94 if (em->start < entry->start) {
95 p = &(*p)->rb_left;
96 } else if (em->start >= extent_map_end(entry)) {
97 p = &(*p)->rb_right;
98 leftmost = false;
99 } else {
100 return -EEXIST;
101 }
102 }
103
104 orig_parent = parent;
105 while (parent && em->start >= extent_map_end(entry)) {
106 parent = rb_next(parent);
107 entry = rb_entry(parent, struct extent_map, rb_node);
108 }
109 if (parent)
110 if (end > entry->start && em->start < extent_map_end(entry))
111 return -EEXIST;
112
113 parent = orig_parent;
114 entry = rb_entry(parent, struct extent_map, rb_node);
115 while (parent && em->start < entry->start) {
116 parent = rb_prev(parent);
117 entry = rb_entry(parent, struct extent_map, rb_node);
118 }
119 if (parent)
120 if (end > entry->start && em->start < extent_map_end(entry))
121 return -EEXIST;
122
123 rb_link_node(&em->rb_node, orig_parent, p);
124 rb_insert_color_cached(&em->rb_node, root, leftmost);
125 return 0;
126}
127
128/*
129 * Search through the tree for an extent_map with a given offset. If it can't
130 * be found, try to find some neighboring extents
131 */
132static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
133 struct rb_node **prev_or_next_ret)
134{
135 struct rb_node *n = root->rb_node;
136 struct rb_node *prev = NULL;
137 struct rb_node *orig_prev = NULL;
138 struct extent_map *entry;
139 struct extent_map *prev_entry = NULL;
140
141 ASSERT(prev_or_next_ret);
142
143 while (n) {
144 entry = rb_entry(n, struct extent_map, rb_node);
145 prev = n;
146 prev_entry = entry;
147
148 if (offset < entry->start)
149 n = n->rb_left;
150 else if (offset >= extent_map_end(entry))
151 n = n->rb_right;
152 else
153 return n;
154 }
155
156 orig_prev = prev;
157 while (prev && offset >= extent_map_end(prev_entry)) {
158 prev = rb_next(prev);
159 prev_entry = rb_entry(prev, struct extent_map, rb_node);
160 }
161
162 /*
163 * Previous extent map found, return as in this case the caller does not
164 * care about the next one.
165 */
166 if (prev) {
167 *prev_or_next_ret = prev;
168 return NULL;
169 }
170
171 prev = orig_prev;
172 prev_entry = rb_entry(prev, struct extent_map, rb_node);
173 while (prev && offset < prev_entry->start) {
174 prev = rb_prev(prev);
175 prev_entry = rb_entry(prev, struct extent_map, rb_node);
176 }
177 *prev_or_next_ret = prev;
178
179 return NULL;
180}
181
182static inline u64 extent_map_block_end(const struct extent_map *em)
183{
184 if (em->block_start + em->block_len < em->block_start)
185 return (u64)-1;
186 return em->block_start + em->block_len;
187}
188
189static bool can_merge_extent_map(const struct extent_map *em)
190{
191 if (em->flags & EXTENT_FLAG_PINNED)
192 return false;
193
194 /* Don't merge compressed extents, we need to know their actual size. */
195 if (extent_map_is_compressed(em))
196 return false;
197
198 if (em->flags & EXTENT_FLAG_LOGGING)
199 return false;
200
201 /*
202 * We don't want to merge stuff that hasn't been written to the log yet
203 * since it may not reflect exactly what is on disk, and that would be
204 * bad.
205 */
206 if (!list_empty(&em->list))
207 return false;
208
209 return true;
210}
211
212/* Check to see if two extent_map structs are adjacent and safe to merge. */
213static bool mergeable_maps(const struct extent_map *prev, const struct extent_map *next)
214{
215 if (extent_map_end(prev) != next->start)
216 return false;
217
218 if (prev->flags != next->flags)
219 return false;
220
221 if (next->block_start < EXTENT_MAP_LAST_BYTE - 1)
222 return next->block_start == extent_map_block_end(prev);
223
224 /* HOLES and INLINE extents. */
225 return next->block_start == prev->block_start;
226}
227
228static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
229{
230 struct extent_map *merge = NULL;
231 struct rb_node *rb;
232
233 /*
234 * We can't modify an extent map that is in the tree and that is being
235 * used by another task, as it can cause that other task to see it in
236 * inconsistent state during the merging. We always have 1 reference for
237 * the tree and 1 for this task (which is unpinning the extent map or
238 * clearing the logging flag), so anything > 2 means it's being used by
239 * other tasks too.
240 */
241 if (refcount_read(&em->refs) > 2)
242 return;
243
244 if (!can_merge_extent_map(em))
245 return;
246
247 if (em->start != 0) {
248 rb = rb_prev(&em->rb_node);
249 if (rb)
250 merge = rb_entry(rb, struct extent_map, rb_node);
251 if (rb && can_merge_extent_map(merge) && mergeable_maps(merge, em)) {
252 em->start = merge->start;
253 em->orig_start = merge->orig_start;
254 em->len += merge->len;
255 em->block_len += merge->block_len;
256 em->block_start = merge->block_start;
257 em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
258 em->mod_start = merge->mod_start;
259 em->generation = max(em->generation, merge->generation);
260 em->flags |= EXTENT_FLAG_MERGED;
261
262 rb_erase_cached(&merge->rb_node, &tree->map);
263 RB_CLEAR_NODE(&merge->rb_node);
264 free_extent_map(merge);
265 }
266 }
267
268 rb = rb_next(&em->rb_node);
269 if (rb)
270 merge = rb_entry(rb, struct extent_map, rb_node);
271 if (rb && can_merge_extent_map(merge) && mergeable_maps(em, merge)) {
272 em->len += merge->len;
273 em->block_len += merge->block_len;
274 rb_erase_cached(&merge->rb_node, &tree->map);
275 RB_CLEAR_NODE(&merge->rb_node);
276 em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
277 em->generation = max(em->generation, merge->generation);
278 em->flags |= EXTENT_FLAG_MERGED;
279 free_extent_map(merge);
280 }
281}
282
283/*
284 * Unpin an extent from the cache.
285 *
286 * @inode: the inode from which we are unpinning an extent range
287 * @start: logical offset in the file
288 * @len: length of the extent
289 * @gen: generation that this extent has been modified in
290 *
291 * Called after an extent has been written to disk properly. Set the generation
292 * to the generation that actually added the file item to the inode so we know
293 * we need to sync this extent when we call fsync().
294 */
295int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen)
296{
297 struct btrfs_fs_info *fs_info = inode->root->fs_info;
298 struct extent_map_tree *tree = &inode->extent_tree;
299 int ret = 0;
300 struct extent_map *em;
301 bool prealloc = false;
302
303 write_lock(&tree->lock);
304 em = lookup_extent_mapping(tree, start, len);
305
306 if (WARN_ON(!em)) {
307 btrfs_warn(fs_info,
308"no extent map found for inode %llu (root %lld) when unpinning extent range [%llu, %llu), generation %llu",
309 btrfs_ino(inode), btrfs_root_id(inode->root),
310 start, len, gen);
311 goto out;
312 }
313
314 if (WARN_ON(em->start != start))
315 btrfs_warn(fs_info,
316"found extent map for inode %llu (root %lld) with unexpected start offset %llu when unpinning extent range [%llu, %llu), generation %llu",
317 btrfs_ino(inode), btrfs_root_id(inode->root),
318 em->start, start, len, gen);
319
320 em->generation = gen;
321 em->flags &= ~EXTENT_FLAG_PINNED;
322 em->mod_start = em->start;
323 em->mod_len = em->len;
324
325 if (em->flags & EXTENT_FLAG_FILLING) {
326 prealloc = true;
327 em->flags &= ~EXTENT_FLAG_FILLING;
328 }
329
330 try_merge_map(tree, em);
331
332 if (prealloc) {
333 em->mod_start = em->start;
334 em->mod_len = em->len;
335 }
336
337 free_extent_map(em);
338out:
339 write_unlock(&tree->lock);
340 return ret;
341
342}
343
344void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
345{
346 lockdep_assert_held_write(&tree->lock);
347
348 em->flags &= ~EXTENT_FLAG_LOGGING;
349 if (extent_map_in_tree(em))
350 try_merge_map(tree, em);
351}
352
353static inline void setup_extent_mapping(struct extent_map_tree *tree,
354 struct extent_map *em,
355 int modified)
356{
357 refcount_inc(&em->refs);
358 em->mod_start = em->start;
359 em->mod_len = em->len;
360
361 ASSERT(list_empty(&em->list));
362
363 if (modified)
364 list_add(&em->list, &tree->modified_extents);
365 else
366 try_merge_map(tree, em);
367}
368
369/*
370 * Add new extent map to the extent tree
371 *
372 * @tree: tree to insert new map in
373 * @em: map to insert
374 * @modified: indicate whether the given @em should be added to the
375 * modified list, which indicates the extent needs to be logged
376 *
377 * Insert @em into @tree or perform a simple forward/backward merge with
378 * existing mappings. The extent_map struct passed in will be inserted
379 * into the tree directly, with an additional reference taken, or a
380 * reference dropped if the merge attempt was successful.
381 */
382static int add_extent_mapping(struct extent_map_tree *tree,
383 struct extent_map *em, int modified)
384{
385 int ret = 0;
386
387 lockdep_assert_held_write(&tree->lock);
388
389 ret = tree_insert(&tree->map, em);
390 if (ret)
391 goto out;
392
393 setup_extent_mapping(tree, em, modified);
394out:
395 return ret;
396}
397
398static struct extent_map *
399__lookup_extent_mapping(struct extent_map_tree *tree,
400 u64 start, u64 len, int strict)
401{
402 struct extent_map *em;
403 struct rb_node *rb_node;
404 struct rb_node *prev_or_next = NULL;
405 u64 end = range_end(start, len);
406
407 rb_node = __tree_search(&tree->map.rb_root, start, &prev_or_next);
408 if (!rb_node) {
409 if (prev_or_next)
410 rb_node = prev_or_next;
411 else
412 return NULL;
413 }
414
415 em = rb_entry(rb_node, struct extent_map, rb_node);
416
417 if (strict && !(end > em->start && start < extent_map_end(em)))
418 return NULL;
419
420 refcount_inc(&em->refs);
421 return em;
422}
423
424/*
425 * Lookup extent_map that intersects @start + @len range.
426 *
427 * @tree: tree to lookup in
428 * @start: byte offset to start the search
429 * @len: length of the lookup range
430 *
431 * Find and return the first extent_map struct in @tree that intersects the
432 * [start, len] range. There may be additional objects in the tree that
433 * intersect, so check the object returned carefully to make sure that no
434 * additional lookups are needed.
435 */
436struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
437 u64 start, u64 len)
438{
439 return __lookup_extent_mapping(tree, start, len, 1);
440}
441
442/*
443 * Find a nearby extent map intersecting @start + @len (not an exact search).
444 *
445 * @tree: tree to lookup in
446 * @start: byte offset to start the search
447 * @len: length of the lookup range
448 *
449 * Find and return the first extent_map struct in @tree that intersects the
450 * [start, len] range.
451 *
452 * If one can't be found, any nearby extent may be returned
453 */
454struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
455 u64 start, u64 len)
456{
457 return __lookup_extent_mapping(tree, start, len, 0);
458}
459
460/*
461 * Remove an extent_map from the extent tree.
462 *
463 * @tree: extent tree to remove from
464 * @em: extent map being removed
465 *
466 * Remove @em from @tree. No reference counts are dropped, and no checks
467 * are done to see if the range is in use.
468 */
469void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
470{
471 lockdep_assert_held_write(&tree->lock);
472
473 WARN_ON(em->flags & EXTENT_FLAG_PINNED);
474 rb_erase_cached(&em->rb_node, &tree->map);
475 if (!(em->flags & EXTENT_FLAG_LOGGING))
476 list_del_init(&em->list);
477 RB_CLEAR_NODE(&em->rb_node);
478}
479
480static void replace_extent_mapping(struct extent_map_tree *tree,
481 struct extent_map *cur,
482 struct extent_map *new,
483 int modified)
484{
485 lockdep_assert_held_write(&tree->lock);
486
487 WARN_ON(cur->flags & EXTENT_FLAG_PINNED);
488 ASSERT(extent_map_in_tree(cur));
489 if (!(cur->flags & EXTENT_FLAG_LOGGING))
490 list_del_init(&cur->list);
491 rb_replace_node_cached(&cur->rb_node, &new->rb_node, &tree->map);
492 RB_CLEAR_NODE(&cur->rb_node);
493
494 setup_extent_mapping(tree, new, modified);
495}
496
497static struct extent_map *next_extent_map(const struct extent_map *em)
498{
499 struct rb_node *next;
500
501 next = rb_next(&em->rb_node);
502 if (!next)
503 return NULL;
504 return container_of(next, struct extent_map, rb_node);
505}
506
507static struct extent_map *prev_extent_map(struct extent_map *em)
508{
509 struct rb_node *prev;
510
511 prev = rb_prev(&em->rb_node);
512 if (!prev)
513 return NULL;
514 return container_of(prev, struct extent_map, rb_node);
515}
516
517/*
518 * Helper for btrfs_get_extent. Given an existing extent in the tree,
519 * the existing extent is the nearest extent to map_start,
520 * and an extent that you want to insert, deal with overlap and insert
521 * the best fitted new extent into the tree.
522 */
523static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
524 struct extent_map *existing,
525 struct extent_map *em,
526 u64 map_start)
527{
528 struct extent_map *prev;
529 struct extent_map *next;
530 u64 start;
531 u64 end;
532 u64 start_diff;
533
534 BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
535
536 if (existing->start > map_start) {
537 next = existing;
538 prev = prev_extent_map(next);
539 } else {
540 prev = existing;
541 next = next_extent_map(prev);
542 }
543
544 start = prev ? extent_map_end(prev) : em->start;
545 start = max_t(u64, start, em->start);
546 end = next ? next->start : extent_map_end(em);
547 end = min_t(u64, end, extent_map_end(em));
548 start_diff = start - em->start;
549 em->start = start;
550 em->len = end - start;
551 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
552 !extent_map_is_compressed(em)) {
553 em->block_start += start_diff;
554 em->block_len = em->len;
555 }
556 return add_extent_mapping(em_tree, em, 0);
557}
558
559/*
560 * Add extent mapping into em_tree.
561 *
562 * @fs_info: the filesystem
563 * @em_tree: extent tree into which we want to insert the extent mapping
564 * @em_in: extent we are inserting
565 * @start: start of the logical range btrfs_get_extent() is requesting
566 * @len: length of the logical range btrfs_get_extent() is requesting
567 *
568 * Note that @em_in's range may be different from [start, start+len),
569 * but they must be overlapped.
570 *
571 * Insert @em_in into @em_tree. In case there is an overlapping range, handle
572 * the -EEXIST by either:
573 * a) Returning the existing extent in @em_in if @start is within the
574 * existing em.
575 * b) Merge the existing extent with @em_in passed in.
576 *
577 * Return 0 on success, otherwise -EEXIST.
578 *
579 */
580int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
581 struct extent_map_tree *em_tree,
582 struct extent_map **em_in, u64 start, u64 len)
583{
584 int ret;
585 struct extent_map *em = *em_in;
586
587 /*
588 * Tree-checker should have rejected any inline extent with non-zero
589 * file offset. Here just do a sanity check.
590 */
591 if (em->block_start == EXTENT_MAP_INLINE)
592 ASSERT(em->start == 0);
593
594 ret = add_extent_mapping(em_tree, em, 0);
595 /* it is possible that someone inserted the extent into the tree
596 * while we had the lock dropped. It is also possible that
597 * an overlapping map exists in the tree
598 */
599 if (ret == -EEXIST) {
600 struct extent_map *existing;
601
602 existing = search_extent_mapping(em_tree, start, len);
603
604 trace_btrfs_handle_em_exist(fs_info, existing, em, start, len);
605
606 /*
607 * existing will always be non-NULL, since there must be
608 * extent causing the -EEXIST.
609 */
610 if (start >= existing->start &&
611 start < extent_map_end(existing)) {
612 free_extent_map(em);
613 *em_in = existing;
614 ret = 0;
615 } else {
616 u64 orig_start = em->start;
617 u64 orig_len = em->len;
618
619 /*
620 * The existing extent map is the one nearest to
621 * the [start, start + len) range which overlaps
622 */
623 ret = merge_extent_mapping(em_tree, existing,
624 em, start);
625 if (ret) {
626 free_extent_map(em);
627 *em_in = NULL;
628 WARN_ONCE(ret,
629"unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
630 ret, existing->start, existing->len,
631 orig_start, orig_len);
632 }
633 free_extent_map(existing);
634 }
635 }
636
637 ASSERT(ret == 0 || ret == -EEXIST);
638 return ret;
639}
640
641/*
642 * Drop all extent maps from a tree in the fastest possible way, rescheduling
643 * if needed. This avoids searching the tree, from the root down to the first
644 * extent map, before each deletion.
645 */
646static void drop_all_extent_maps_fast(struct extent_map_tree *tree)
647{
648 write_lock(&tree->lock);
649 while (!RB_EMPTY_ROOT(&tree->map.rb_root)) {
650 struct extent_map *em;
651 struct rb_node *node;
652
653 node = rb_first_cached(&tree->map);
654 em = rb_entry(node, struct extent_map, rb_node);
655 em->flags &= ~(EXTENT_FLAG_PINNED | EXTENT_FLAG_LOGGING);
656 remove_extent_mapping(tree, em);
657 free_extent_map(em);
658 cond_resched_rwlock_write(&tree->lock);
659 }
660 write_unlock(&tree->lock);
661}
662
663/*
664 * Drop all extent maps in a given range.
665 *
666 * @inode: The target inode.
667 * @start: Start offset of the range.
668 * @end: End offset of the range (inclusive value).
669 * @skip_pinned: Indicate if pinned extent maps should be ignored or not.
670 *
671 * This drops all the extent maps that intersect the given range [@start, @end].
672 * Extent maps that partially overlap the range and extend behind or beyond it,
673 * are split.
674 * The caller should have locked an appropriate file range in the inode's io
675 * tree before calling this function.
676 */
677void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end,
678 bool skip_pinned)
679{
680 struct extent_map *split;
681 struct extent_map *split2;
682 struct extent_map *em;
683 struct extent_map_tree *em_tree = &inode->extent_tree;
684 u64 len = end - start + 1;
685
686 WARN_ON(end < start);
687 if (end == (u64)-1) {
688 if (start == 0 && !skip_pinned) {
689 drop_all_extent_maps_fast(em_tree);
690 return;
691 }
692 len = (u64)-1;
693 } else {
694 /* Make end offset exclusive for use in the loop below. */
695 end++;
696 }
697
698 /*
699 * It's ok if we fail to allocate the extent maps, see the comment near
700 * the bottom of the loop below. We only need two spare extent maps in
701 * the worst case, where the first extent map that intersects our range
702 * starts before the range and the last extent map that intersects our
703 * range ends after our range (and they might be the same extent map),
704 * because we need to split those two extent maps at the boundaries.
705 */
706 split = alloc_extent_map();
707 split2 = alloc_extent_map();
708
709 write_lock(&em_tree->lock);
710 em = lookup_extent_mapping(em_tree, start, len);
711
712 while (em) {
713 /* extent_map_end() returns exclusive value (last byte + 1). */
714 const u64 em_end = extent_map_end(em);
715 struct extent_map *next_em = NULL;
716 u64 gen;
717 unsigned long flags;
718 bool modified;
719 bool compressed;
720
721 if (em_end < end) {
722 next_em = next_extent_map(em);
723 if (next_em) {
724 if (next_em->start < end)
725 refcount_inc(&next_em->refs);
726 else
727 next_em = NULL;
728 }
729 }
730
731 if (skip_pinned && (em->flags & EXTENT_FLAG_PINNED)) {
732 start = em_end;
733 goto next;
734 }
735
736 flags = em->flags;
737 /*
738 * In case we split the extent map, we want to preserve the
739 * EXTENT_FLAG_LOGGING flag on our extent map, but we don't want
740 * it on the new extent maps.
741 */
742 em->flags &= ~(EXTENT_FLAG_PINNED | EXTENT_FLAG_LOGGING);
743 modified = !list_empty(&em->list);
744
745 /*
746 * The extent map does not cross our target range, so no need to
747 * split it, we can remove it directly.
748 */
749 if (em->start >= start && em_end <= end)
750 goto remove_em;
751
752 gen = em->generation;
753 compressed = extent_map_is_compressed(em);
754
755 if (em->start < start) {
756 if (!split) {
757 split = split2;
758 split2 = NULL;
759 if (!split)
760 goto remove_em;
761 }
762 split->start = em->start;
763 split->len = start - em->start;
764
765 if (em->block_start < EXTENT_MAP_LAST_BYTE) {
766 split->orig_start = em->orig_start;
767 split->block_start = em->block_start;
768
769 if (compressed)
770 split->block_len = em->block_len;
771 else
772 split->block_len = split->len;
773 split->orig_block_len = max(split->block_len,
774 em->orig_block_len);
775 split->ram_bytes = em->ram_bytes;
776 } else {
777 split->orig_start = split->start;
778 split->block_len = 0;
779 split->block_start = em->block_start;
780 split->orig_block_len = 0;
781 split->ram_bytes = split->len;
782 }
783
784 split->generation = gen;
785 split->flags = flags;
786 replace_extent_mapping(em_tree, em, split, modified);
787 free_extent_map(split);
788 split = split2;
789 split2 = NULL;
790 }
791 if (em_end > end) {
792 if (!split) {
793 split = split2;
794 split2 = NULL;
795 if (!split)
796 goto remove_em;
797 }
798 split->start = end;
799 split->len = em_end - end;
800 split->block_start = em->block_start;
801 split->flags = flags;
802 split->generation = gen;
803
804 if (em->block_start < EXTENT_MAP_LAST_BYTE) {
805 split->orig_block_len = max(em->block_len,
806 em->orig_block_len);
807
808 split->ram_bytes = em->ram_bytes;
809 if (compressed) {
810 split->block_len = em->block_len;
811 split->orig_start = em->orig_start;
812 } else {
813 const u64 diff = start + len - em->start;
814
815 split->block_len = split->len;
816 split->block_start += diff;
817 split->orig_start = em->orig_start;
818 }
819 } else {
820 split->ram_bytes = split->len;
821 split->orig_start = split->start;
822 split->block_len = 0;
823 split->orig_block_len = 0;
824 }
825
826 if (extent_map_in_tree(em)) {
827 replace_extent_mapping(em_tree, em, split,
828 modified);
829 } else {
830 int ret;
831
832 ret = add_extent_mapping(em_tree, split,
833 modified);
834 /* Logic error, shouldn't happen. */
835 ASSERT(ret == 0);
836 if (WARN_ON(ret != 0) && modified)
837 btrfs_set_inode_full_sync(inode);
838 }
839 free_extent_map(split);
840 split = NULL;
841 }
842remove_em:
843 if (extent_map_in_tree(em)) {
844 /*
845 * If the extent map is still in the tree it means that
846 * either of the following is true:
847 *
848 * 1) It fits entirely in our range (doesn't end beyond
849 * it or starts before it);
850 *
851 * 2) It starts before our range and/or ends after our
852 * range, and we were not able to allocate the extent
853 * maps for split operations, @split and @split2.
854 *
855 * If we are at case 2) then we just remove the entire
856 * extent map - this is fine since if anyone needs it to
857 * access the subranges outside our range, will just
858 * load it again from the subvolume tree's file extent
859 * item. However if the extent map was in the list of
860 * modified extents, then we must mark the inode for a
861 * full fsync, otherwise a fast fsync will miss this
862 * extent if it's new and needs to be logged.
863 */
864 if ((em->start < start || em_end > end) && modified) {
865 ASSERT(!split);
866 btrfs_set_inode_full_sync(inode);
867 }
868 remove_extent_mapping(em_tree, em);
869 }
870
871 /*
872 * Once for the tree reference (we replaced or removed the
873 * extent map from the tree).
874 */
875 free_extent_map(em);
876next:
877 /* Once for us (for our lookup reference). */
878 free_extent_map(em);
879
880 em = next_em;
881 }
882
883 write_unlock(&em_tree->lock);
884
885 free_extent_map(split);
886 free_extent_map(split2);
887}
888
889/*
890 * Replace a range in the inode's extent map tree with a new extent map.
891 *
892 * @inode: The target inode.
893 * @new_em: The new extent map to add to the inode's extent map tree.
894 * @modified: Indicate if the new extent map should be added to the list of
895 * modified extents (for fast fsync tracking).
896 *
897 * Drops all the extent maps in the inode's extent map tree that intersect the
898 * range of the new extent map and adds the new extent map to the tree.
899 * The caller should have locked an appropriate file range in the inode's io
900 * tree before calling this function.
901 */
902int btrfs_replace_extent_map_range(struct btrfs_inode *inode,
903 struct extent_map *new_em,
904 bool modified)
905{
906 const u64 end = new_em->start + new_em->len - 1;
907 struct extent_map_tree *tree = &inode->extent_tree;
908 int ret;
909
910 ASSERT(!extent_map_in_tree(new_em));
911
912 /*
913 * The caller has locked an appropriate file range in the inode's io
914 * tree, but getting -EEXIST when adding the new extent map can still
915 * happen in case there are extents that partially cover the range, and
916 * this is due to two tasks operating on different parts of the extent.
917 * See commit 18e83ac75bfe67 ("Btrfs: fix unexpected EEXIST from
918 * btrfs_get_extent") for an example and details.
919 */
920 do {
921 btrfs_drop_extent_map_range(inode, new_em->start, end, false);
922 write_lock(&tree->lock);
923 ret = add_extent_mapping(tree, new_em, modified);
924 write_unlock(&tree->lock);
925 } while (ret == -EEXIST);
926
927 return ret;
928}
929
930/*
931 * Split off the first pre bytes from the extent_map at [start, start + len],
932 * and set the block_start for it to new_logical.
933 *
934 * This function is used when an ordered_extent needs to be split.
935 */
936int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
937 u64 new_logical)
938{
939 struct extent_map_tree *em_tree = &inode->extent_tree;
940 struct extent_map *em;
941 struct extent_map *split_pre = NULL;
942 struct extent_map *split_mid = NULL;
943 int ret = 0;
944 unsigned long flags;
945
946 ASSERT(pre != 0);
947 ASSERT(pre < len);
948
949 split_pre = alloc_extent_map();
950 if (!split_pre)
951 return -ENOMEM;
952 split_mid = alloc_extent_map();
953 if (!split_mid) {
954 ret = -ENOMEM;
955 goto out_free_pre;
956 }
957
958 lock_extent(&inode->io_tree, start, start + len - 1, NULL);
959 write_lock(&em_tree->lock);
960 em = lookup_extent_mapping(em_tree, start, len);
961 if (!em) {
962 ret = -EIO;
963 goto out_unlock;
964 }
965
966 ASSERT(em->len == len);
967 ASSERT(!extent_map_is_compressed(em));
968 ASSERT(em->block_start < EXTENT_MAP_LAST_BYTE);
969 ASSERT(em->flags & EXTENT_FLAG_PINNED);
970 ASSERT(!(em->flags & EXTENT_FLAG_LOGGING));
971 ASSERT(!list_empty(&em->list));
972
973 flags = em->flags;
974 em->flags &= ~EXTENT_FLAG_PINNED;
975
976 /* First, replace the em with a new extent_map starting from * em->start */
977 split_pre->start = em->start;
978 split_pre->len = pre;
979 split_pre->orig_start = split_pre->start;
980 split_pre->block_start = new_logical;
981 split_pre->block_len = split_pre->len;
982 split_pre->orig_block_len = split_pre->block_len;
983 split_pre->ram_bytes = split_pre->len;
984 split_pre->flags = flags;
985 split_pre->generation = em->generation;
986
987 replace_extent_mapping(em_tree, em, split_pre, 1);
988
989 /*
990 * Now we only have an extent_map at:
991 * [em->start, em->start + pre]
992 */
993
994 /* Insert the middle extent_map. */
995 split_mid->start = em->start + pre;
996 split_mid->len = em->len - pre;
997 split_mid->orig_start = split_mid->start;
998 split_mid->block_start = em->block_start + pre;
999 split_mid->block_len = split_mid->len;
1000 split_mid->orig_block_len = split_mid->block_len;
1001 split_mid->ram_bytes = split_mid->len;
1002 split_mid->flags = flags;
1003 split_mid->generation = em->generation;
1004 add_extent_mapping(em_tree, split_mid, 1);
1005
1006 /* Once for us */
1007 free_extent_map(em);
1008 /* Once for the tree */
1009 free_extent_map(em);
1010
1011out_unlock:
1012 write_unlock(&em_tree->lock);
1013 unlock_extent(&inode->io_tree, start, start + len - 1, NULL);
1014 free_extent_map(split_mid);
1015out_free_pre:
1016 free_extent_map(split_pre);
1017 return ret;
1018}
1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/err.h>
4#include <linux/slab.h>
5#include <linux/spinlock.h>
6#include "messages.h"
7#include "ctree.h"
8#include "extent_map.h"
9#include "compression.h"
10#include "btrfs_inode.h"
11
12
13static struct kmem_cache *extent_map_cache;
14
15int __init extent_map_init(void)
16{
17 extent_map_cache = kmem_cache_create("btrfs_extent_map",
18 sizeof(struct extent_map), 0, 0, NULL);
19 if (!extent_map_cache)
20 return -ENOMEM;
21 return 0;
22}
23
24void __cold extent_map_exit(void)
25{
26 kmem_cache_destroy(extent_map_cache);
27}
28
29/*
30 * Initialize the extent tree @tree. Should be called for each new inode or
31 * other user of the extent_map interface.
32 */
33void extent_map_tree_init(struct extent_map_tree *tree)
34{
35 tree->map = RB_ROOT_CACHED;
36 INIT_LIST_HEAD(&tree->modified_extents);
37 rwlock_init(&tree->lock);
38}
39
40/*
41 * Allocate a new extent_map structure. The new structure is returned with a
42 * reference count of one and needs to be freed using free_extent_map()
43 */
44struct extent_map *alloc_extent_map(void)
45{
46 struct extent_map *em;
47 em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
48 if (!em)
49 return NULL;
50 RB_CLEAR_NODE(&em->rb_node);
51 refcount_set(&em->refs, 1);
52 INIT_LIST_HEAD(&em->list);
53 return em;
54}
55
56/*
57 * Drop the reference out on @em by one and free the structure if the reference
58 * count hits zero.
59 */
60void free_extent_map(struct extent_map *em)
61{
62 if (!em)
63 return;
64 if (refcount_dec_and_test(&em->refs)) {
65 WARN_ON(extent_map_in_tree(em));
66 WARN_ON(!list_empty(&em->list));
67 kmem_cache_free(extent_map_cache, em);
68 }
69}
70
71/* Do the math around the end of an extent, handling wrapping. */
72static u64 range_end(u64 start, u64 len)
73{
74 if (start + len < start)
75 return (u64)-1;
76 return start + len;
77}
78
79static int tree_insert(struct rb_root_cached *root, struct extent_map *em)
80{
81 struct rb_node **p = &root->rb_root.rb_node;
82 struct rb_node *parent = NULL;
83 struct extent_map *entry = NULL;
84 struct rb_node *orig_parent = NULL;
85 u64 end = range_end(em->start, em->len);
86 bool leftmost = true;
87
88 while (*p) {
89 parent = *p;
90 entry = rb_entry(parent, struct extent_map, rb_node);
91
92 if (em->start < entry->start) {
93 p = &(*p)->rb_left;
94 } else if (em->start >= extent_map_end(entry)) {
95 p = &(*p)->rb_right;
96 leftmost = false;
97 } else {
98 return -EEXIST;
99 }
100 }
101
102 orig_parent = parent;
103 while (parent && em->start >= extent_map_end(entry)) {
104 parent = rb_next(parent);
105 entry = rb_entry(parent, struct extent_map, rb_node);
106 }
107 if (parent)
108 if (end > entry->start && em->start < extent_map_end(entry))
109 return -EEXIST;
110
111 parent = orig_parent;
112 entry = rb_entry(parent, struct extent_map, rb_node);
113 while (parent && em->start < entry->start) {
114 parent = rb_prev(parent);
115 entry = rb_entry(parent, struct extent_map, rb_node);
116 }
117 if (parent)
118 if (end > entry->start && em->start < extent_map_end(entry))
119 return -EEXIST;
120
121 rb_link_node(&em->rb_node, orig_parent, p);
122 rb_insert_color_cached(&em->rb_node, root, leftmost);
123 return 0;
124}
125
126/*
127 * Search through the tree for an extent_map with a given offset. If it can't
128 * be found, try to find some neighboring extents
129 */
130static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
131 struct rb_node **prev_or_next_ret)
132{
133 struct rb_node *n = root->rb_node;
134 struct rb_node *prev = NULL;
135 struct rb_node *orig_prev = NULL;
136 struct extent_map *entry;
137 struct extent_map *prev_entry = NULL;
138
139 ASSERT(prev_or_next_ret);
140
141 while (n) {
142 entry = rb_entry(n, struct extent_map, rb_node);
143 prev = n;
144 prev_entry = entry;
145
146 if (offset < entry->start)
147 n = n->rb_left;
148 else if (offset >= extent_map_end(entry))
149 n = n->rb_right;
150 else
151 return n;
152 }
153
154 orig_prev = prev;
155 while (prev && offset >= extent_map_end(prev_entry)) {
156 prev = rb_next(prev);
157 prev_entry = rb_entry(prev, struct extent_map, rb_node);
158 }
159
160 /*
161 * Previous extent map found, return as in this case the caller does not
162 * care about the next one.
163 */
164 if (prev) {
165 *prev_or_next_ret = prev;
166 return NULL;
167 }
168
169 prev = orig_prev;
170 prev_entry = rb_entry(prev, struct extent_map, rb_node);
171 while (prev && offset < prev_entry->start) {
172 prev = rb_prev(prev);
173 prev_entry = rb_entry(prev, struct extent_map, rb_node);
174 }
175 *prev_or_next_ret = prev;
176
177 return NULL;
178}
179
180static inline u64 extent_map_block_end(const struct extent_map *em)
181{
182 if (em->block_start + em->block_len < em->block_start)
183 return (u64)-1;
184 return em->block_start + em->block_len;
185}
186
187static bool can_merge_extent_map(const struct extent_map *em)
188{
189 if (em->flags & EXTENT_FLAG_PINNED)
190 return false;
191
192 /* Don't merge compressed extents, we need to know their actual size. */
193 if (extent_map_is_compressed(em))
194 return false;
195
196 if (em->flags & EXTENT_FLAG_LOGGING)
197 return false;
198
199 /*
200 * We don't want to merge stuff that hasn't been written to the log yet
201 * since it may not reflect exactly what is on disk, and that would be
202 * bad.
203 */
204 if (!list_empty(&em->list))
205 return false;
206
207 return true;
208}
209
210/* Check to see if two extent_map structs are adjacent and safe to merge. */
211static bool mergeable_maps(const struct extent_map *prev, const struct extent_map *next)
212{
213 if (extent_map_end(prev) != next->start)
214 return false;
215
216 if (prev->flags != next->flags)
217 return false;
218
219 if (next->block_start < EXTENT_MAP_LAST_BYTE - 1)
220 return next->block_start == extent_map_block_end(prev);
221
222 /* HOLES and INLINE extents. */
223 return next->block_start == prev->block_start;
224}
225
226static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
227{
228 struct extent_map *merge = NULL;
229 struct rb_node *rb;
230
231 /*
232 * We can't modify an extent map that is in the tree and that is being
233 * used by another task, as it can cause that other task to see it in
234 * inconsistent state during the merging. We always have 1 reference for
235 * the tree and 1 for this task (which is unpinning the extent map or
236 * clearing the logging flag), so anything > 2 means it's being used by
237 * other tasks too.
238 */
239 if (refcount_read(&em->refs) > 2)
240 return;
241
242 if (!can_merge_extent_map(em))
243 return;
244
245 if (em->start != 0) {
246 rb = rb_prev(&em->rb_node);
247 if (rb)
248 merge = rb_entry(rb, struct extent_map, rb_node);
249 if (rb && can_merge_extent_map(merge) && mergeable_maps(merge, em)) {
250 em->start = merge->start;
251 em->orig_start = merge->orig_start;
252 em->len += merge->len;
253 em->block_len += merge->block_len;
254 em->block_start = merge->block_start;
255 em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
256 em->mod_start = merge->mod_start;
257 em->generation = max(em->generation, merge->generation);
258 em->flags |= EXTENT_FLAG_MERGED;
259
260 rb_erase_cached(&merge->rb_node, &tree->map);
261 RB_CLEAR_NODE(&merge->rb_node);
262 free_extent_map(merge);
263 }
264 }
265
266 rb = rb_next(&em->rb_node);
267 if (rb)
268 merge = rb_entry(rb, struct extent_map, rb_node);
269 if (rb && can_merge_extent_map(merge) && mergeable_maps(em, merge)) {
270 em->len += merge->len;
271 em->block_len += merge->block_len;
272 rb_erase_cached(&merge->rb_node, &tree->map);
273 RB_CLEAR_NODE(&merge->rb_node);
274 em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
275 em->generation = max(em->generation, merge->generation);
276 em->flags |= EXTENT_FLAG_MERGED;
277 free_extent_map(merge);
278 }
279}
280
281/*
282 * Unpin an extent from the cache.
283 *
284 * @inode: the inode from which we are unpinning an extent range
285 * @start: logical offset in the file
286 * @len: length of the extent
287 * @gen: generation that this extent has been modified in
288 *
289 * Called after an extent has been written to disk properly. Set the generation
290 * to the generation that actually added the file item to the inode so we know
291 * we need to sync this extent when we call fsync().
292 *
293 * Returns: 0 on success
294 * -ENOENT when the extent is not found in the tree
295 * -EUCLEAN if the found extent does not match the expected start
296 */
297int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen)
298{
299 struct btrfs_fs_info *fs_info = inode->root->fs_info;
300 struct extent_map_tree *tree = &inode->extent_tree;
301 int ret = 0;
302 struct extent_map *em;
303 bool prealloc = false;
304
305 write_lock(&tree->lock);
306 em = lookup_extent_mapping(tree, start, len);
307
308 if (WARN_ON(!em)) {
309 btrfs_warn(fs_info,
310"no extent map found for inode %llu (root %lld) when unpinning extent range [%llu, %llu), generation %llu",
311 btrfs_ino(inode), btrfs_root_id(inode->root),
312 start, start + len, gen);
313 ret = -ENOENT;
314 goto out;
315 }
316
317 if (WARN_ON(em->start != start)) {
318 btrfs_warn(fs_info,
319"found extent map for inode %llu (root %lld) with unexpected start offset %llu when unpinning extent range [%llu, %llu), generation %llu",
320 btrfs_ino(inode), btrfs_root_id(inode->root),
321 em->start, start, start + len, gen);
322 ret = -EUCLEAN;
323 goto out;
324 }
325
326 em->generation = gen;
327 em->flags &= ~EXTENT_FLAG_PINNED;
328 em->mod_start = em->start;
329 em->mod_len = em->len;
330
331 if (em->flags & EXTENT_FLAG_FILLING) {
332 prealloc = true;
333 em->flags &= ~EXTENT_FLAG_FILLING;
334 }
335
336 try_merge_map(tree, em);
337
338 if (prealloc) {
339 em->mod_start = em->start;
340 em->mod_len = em->len;
341 }
342
343out:
344 write_unlock(&tree->lock);
345 free_extent_map(em);
346 return ret;
347
348}
349
350void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
351{
352 lockdep_assert_held_write(&tree->lock);
353
354 em->flags &= ~EXTENT_FLAG_LOGGING;
355 if (extent_map_in_tree(em))
356 try_merge_map(tree, em);
357}
358
359static inline void setup_extent_mapping(struct extent_map_tree *tree,
360 struct extent_map *em,
361 int modified)
362{
363 refcount_inc(&em->refs);
364 em->mod_start = em->start;
365 em->mod_len = em->len;
366
367 ASSERT(list_empty(&em->list));
368
369 if (modified)
370 list_add(&em->list, &tree->modified_extents);
371 else
372 try_merge_map(tree, em);
373}
374
375/*
376 * Add new extent map to the extent tree
377 *
378 * @tree: tree to insert new map in
379 * @em: map to insert
380 * @modified: indicate whether the given @em should be added to the
381 * modified list, which indicates the extent needs to be logged
382 *
383 * Insert @em into @tree or perform a simple forward/backward merge with
384 * existing mappings. The extent_map struct passed in will be inserted
385 * into the tree directly, with an additional reference taken, or a
386 * reference dropped if the merge attempt was successful.
387 */
388static int add_extent_mapping(struct extent_map_tree *tree,
389 struct extent_map *em, int modified)
390{
391 int ret = 0;
392
393 lockdep_assert_held_write(&tree->lock);
394
395 ret = tree_insert(&tree->map, em);
396 if (ret)
397 goto out;
398
399 setup_extent_mapping(tree, em, modified);
400out:
401 return ret;
402}
403
404static struct extent_map *
405__lookup_extent_mapping(struct extent_map_tree *tree,
406 u64 start, u64 len, int strict)
407{
408 struct extent_map *em;
409 struct rb_node *rb_node;
410 struct rb_node *prev_or_next = NULL;
411 u64 end = range_end(start, len);
412
413 rb_node = __tree_search(&tree->map.rb_root, start, &prev_or_next);
414 if (!rb_node) {
415 if (prev_or_next)
416 rb_node = prev_or_next;
417 else
418 return NULL;
419 }
420
421 em = rb_entry(rb_node, struct extent_map, rb_node);
422
423 if (strict && !(end > em->start && start < extent_map_end(em)))
424 return NULL;
425
426 refcount_inc(&em->refs);
427 return em;
428}
429
430/*
431 * Lookup extent_map that intersects @start + @len range.
432 *
433 * @tree: tree to lookup in
434 * @start: byte offset to start the search
435 * @len: length of the lookup range
436 *
437 * Find and return the first extent_map struct in @tree that intersects the
438 * [start, len] range. There may be additional objects in the tree that
439 * intersect, so check the object returned carefully to make sure that no
440 * additional lookups are needed.
441 */
442struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
443 u64 start, u64 len)
444{
445 return __lookup_extent_mapping(tree, start, len, 1);
446}
447
448/*
449 * Find a nearby extent map intersecting @start + @len (not an exact search).
450 *
451 * @tree: tree to lookup in
452 * @start: byte offset to start the search
453 * @len: length of the lookup range
454 *
455 * Find and return the first extent_map struct in @tree that intersects the
456 * [start, len] range.
457 *
458 * If one can't be found, any nearby extent may be returned
459 */
460struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
461 u64 start, u64 len)
462{
463 return __lookup_extent_mapping(tree, start, len, 0);
464}
465
466/*
467 * Remove an extent_map from the extent tree.
468 *
469 * @tree: extent tree to remove from
470 * @em: extent map being removed
471 *
472 * Remove @em from @tree. No reference counts are dropped, and no checks
473 * are done to see if the range is in use.
474 */
475void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
476{
477 lockdep_assert_held_write(&tree->lock);
478
479 WARN_ON(em->flags & EXTENT_FLAG_PINNED);
480 rb_erase_cached(&em->rb_node, &tree->map);
481 if (!(em->flags & EXTENT_FLAG_LOGGING))
482 list_del_init(&em->list);
483 RB_CLEAR_NODE(&em->rb_node);
484}
485
486static void replace_extent_mapping(struct extent_map_tree *tree,
487 struct extent_map *cur,
488 struct extent_map *new,
489 int modified)
490{
491 lockdep_assert_held_write(&tree->lock);
492
493 WARN_ON(cur->flags & EXTENT_FLAG_PINNED);
494 ASSERT(extent_map_in_tree(cur));
495 if (!(cur->flags & EXTENT_FLAG_LOGGING))
496 list_del_init(&cur->list);
497 rb_replace_node_cached(&cur->rb_node, &new->rb_node, &tree->map);
498 RB_CLEAR_NODE(&cur->rb_node);
499
500 setup_extent_mapping(tree, new, modified);
501}
502
503static struct extent_map *next_extent_map(const struct extent_map *em)
504{
505 struct rb_node *next;
506
507 next = rb_next(&em->rb_node);
508 if (!next)
509 return NULL;
510 return container_of(next, struct extent_map, rb_node);
511}
512
513static struct extent_map *prev_extent_map(struct extent_map *em)
514{
515 struct rb_node *prev;
516
517 prev = rb_prev(&em->rb_node);
518 if (!prev)
519 return NULL;
520 return container_of(prev, struct extent_map, rb_node);
521}
522
523/*
524 * Helper for btrfs_get_extent. Given an existing extent in the tree,
525 * the existing extent is the nearest extent to map_start,
526 * and an extent that you want to insert, deal with overlap and insert
527 * the best fitted new extent into the tree.
528 */
529static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
530 struct extent_map *existing,
531 struct extent_map *em,
532 u64 map_start)
533{
534 struct extent_map *prev;
535 struct extent_map *next;
536 u64 start;
537 u64 end;
538 u64 start_diff;
539
540 if (map_start < em->start || map_start >= extent_map_end(em))
541 return -EINVAL;
542
543 if (existing->start > map_start) {
544 next = existing;
545 prev = prev_extent_map(next);
546 } else {
547 prev = existing;
548 next = next_extent_map(prev);
549 }
550
551 start = prev ? extent_map_end(prev) : em->start;
552 start = max_t(u64, start, em->start);
553 end = next ? next->start : extent_map_end(em);
554 end = min_t(u64, end, extent_map_end(em));
555 start_diff = start - em->start;
556 em->start = start;
557 em->len = end - start;
558 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
559 !extent_map_is_compressed(em)) {
560 em->block_start += start_diff;
561 em->block_len = em->len;
562 }
563 return add_extent_mapping(em_tree, em, 0);
564}
565
566/*
567 * Add extent mapping into em_tree.
568 *
569 * @fs_info: the filesystem
570 * @em_tree: extent tree into which we want to insert the extent mapping
571 * @em_in: extent we are inserting
572 * @start: start of the logical range btrfs_get_extent() is requesting
573 * @len: length of the logical range btrfs_get_extent() is requesting
574 *
575 * Note that @em_in's range may be different from [start, start+len),
576 * but they must be overlapped.
577 *
578 * Insert @em_in into @em_tree. In case there is an overlapping range, handle
579 * the -EEXIST by either:
580 * a) Returning the existing extent in @em_in if @start is within the
581 * existing em.
582 * b) Merge the existing extent with @em_in passed in.
583 *
584 * Return 0 on success, otherwise -EEXIST.
585 *
586 */
587int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
588 struct extent_map_tree *em_tree,
589 struct extent_map **em_in, u64 start, u64 len)
590{
591 int ret;
592 struct extent_map *em = *em_in;
593
594 /*
595 * Tree-checker should have rejected any inline extent with non-zero
596 * file offset. Here just do a sanity check.
597 */
598 if (em->block_start == EXTENT_MAP_INLINE)
599 ASSERT(em->start == 0);
600
601 ret = add_extent_mapping(em_tree, em, 0);
602 /* it is possible that someone inserted the extent into the tree
603 * while we had the lock dropped. It is also possible that
604 * an overlapping map exists in the tree
605 */
606 if (ret == -EEXIST) {
607 struct extent_map *existing;
608
609 existing = search_extent_mapping(em_tree, start, len);
610
611 trace_btrfs_handle_em_exist(fs_info, existing, em, start, len);
612
613 /*
614 * existing will always be non-NULL, since there must be
615 * extent causing the -EEXIST.
616 */
617 if (start >= existing->start &&
618 start < extent_map_end(existing)) {
619 free_extent_map(em);
620 *em_in = existing;
621 ret = 0;
622 } else {
623 u64 orig_start = em->start;
624 u64 orig_len = em->len;
625
626 /*
627 * The existing extent map is the one nearest to
628 * the [start, start + len) range which overlaps
629 */
630 ret = merge_extent_mapping(em_tree, existing,
631 em, start);
632 if (WARN_ON(ret)) {
633 free_extent_map(em);
634 *em_in = NULL;
635 btrfs_warn(fs_info,
636"extent map merge error existing [%llu, %llu) with em [%llu, %llu) start %llu",
637 existing->start, extent_map_end(existing),
638 orig_start, orig_start + orig_len, start);
639 }
640 free_extent_map(existing);
641 }
642 }
643
644 ASSERT(ret == 0 || ret == -EEXIST);
645 return ret;
646}
647
648/*
649 * Drop all extent maps from a tree in the fastest possible way, rescheduling
650 * if needed. This avoids searching the tree, from the root down to the first
651 * extent map, before each deletion.
652 */
653static void drop_all_extent_maps_fast(struct extent_map_tree *tree)
654{
655 write_lock(&tree->lock);
656 while (!RB_EMPTY_ROOT(&tree->map.rb_root)) {
657 struct extent_map *em;
658 struct rb_node *node;
659
660 node = rb_first_cached(&tree->map);
661 em = rb_entry(node, struct extent_map, rb_node);
662 em->flags &= ~(EXTENT_FLAG_PINNED | EXTENT_FLAG_LOGGING);
663 remove_extent_mapping(tree, em);
664 free_extent_map(em);
665 cond_resched_rwlock_write(&tree->lock);
666 }
667 write_unlock(&tree->lock);
668}
669
670/*
671 * Drop all extent maps in a given range.
672 *
673 * @inode: The target inode.
674 * @start: Start offset of the range.
675 * @end: End offset of the range (inclusive value).
676 * @skip_pinned: Indicate if pinned extent maps should be ignored or not.
677 *
678 * This drops all the extent maps that intersect the given range [@start, @end].
679 * Extent maps that partially overlap the range and extend behind or beyond it,
680 * are split.
681 * The caller should have locked an appropriate file range in the inode's io
682 * tree before calling this function.
683 */
684void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end,
685 bool skip_pinned)
686{
687 struct extent_map *split;
688 struct extent_map *split2;
689 struct extent_map *em;
690 struct extent_map_tree *em_tree = &inode->extent_tree;
691 u64 len = end - start + 1;
692
693 WARN_ON(end < start);
694 if (end == (u64)-1) {
695 if (start == 0 && !skip_pinned) {
696 drop_all_extent_maps_fast(em_tree);
697 return;
698 }
699 len = (u64)-1;
700 } else {
701 /* Make end offset exclusive for use in the loop below. */
702 end++;
703 }
704
705 /*
706 * It's ok if we fail to allocate the extent maps, see the comment near
707 * the bottom of the loop below. We only need two spare extent maps in
708 * the worst case, where the first extent map that intersects our range
709 * starts before the range and the last extent map that intersects our
710 * range ends after our range (and they might be the same extent map),
711 * because we need to split those two extent maps at the boundaries.
712 */
713 split = alloc_extent_map();
714 split2 = alloc_extent_map();
715
716 write_lock(&em_tree->lock);
717 em = lookup_extent_mapping(em_tree, start, len);
718
719 while (em) {
720 /* extent_map_end() returns exclusive value (last byte + 1). */
721 const u64 em_end = extent_map_end(em);
722 struct extent_map *next_em = NULL;
723 u64 gen;
724 unsigned long flags;
725 bool modified;
726 bool compressed;
727
728 if (em_end < end) {
729 next_em = next_extent_map(em);
730 if (next_em) {
731 if (next_em->start < end)
732 refcount_inc(&next_em->refs);
733 else
734 next_em = NULL;
735 }
736 }
737
738 if (skip_pinned && (em->flags & EXTENT_FLAG_PINNED)) {
739 start = em_end;
740 goto next;
741 }
742
743 flags = em->flags;
744 /*
745 * In case we split the extent map, we want to preserve the
746 * EXTENT_FLAG_LOGGING flag on our extent map, but we don't want
747 * it on the new extent maps.
748 */
749 em->flags &= ~(EXTENT_FLAG_PINNED | EXTENT_FLAG_LOGGING);
750 modified = !list_empty(&em->list);
751
752 /*
753 * The extent map does not cross our target range, so no need to
754 * split it, we can remove it directly.
755 */
756 if (em->start >= start && em_end <= end)
757 goto remove_em;
758
759 gen = em->generation;
760 compressed = extent_map_is_compressed(em);
761
762 if (em->start < start) {
763 if (!split) {
764 split = split2;
765 split2 = NULL;
766 if (!split)
767 goto remove_em;
768 }
769 split->start = em->start;
770 split->len = start - em->start;
771
772 if (em->block_start < EXTENT_MAP_LAST_BYTE) {
773 split->orig_start = em->orig_start;
774 split->block_start = em->block_start;
775
776 if (compressed)
777 split->block_len = em->block_len;
778 else
779 split->block_len = split->len;
780 split->orig_block_len = max(split->block_len,
781 em->orig_block_len);
782 split->ram_bytes = em->ram_bytes;
783 } else {
784 split->orig_start = split->start;
785 split->block_len = 0;
786 split->block_start = em->block_start;
787 split->orig_block_len = 0;
788 split->ram_bytes = split->len;
789 }
790
791 split->generation = gen;
792 split->flags = flags;
793 replace_extent_mapping(em_tree, em, split, modified);
794 free_extent_map(split);
795 split = split2;
796 split2 = NULL;
797 }
798 if (em_end > end) {
799 if (!split) {
800 split = split2;
801 split2 = NULL;
802 if (!split)
803 goto remove_em;
804 }
805 split->start = end;
806 split->len = em_end - end;
807 split->block_start = em->block_start;
808 split->flags = flags;
809 split->generation = gen;
810
811 if (em->block_start < EXTENT_MAP_LAST_BYTE) {
812 split->orig_block_len = max(em->block_len,
813 em->orig_block_len);
814
815 split->ram_bytes = em->ram_bytes;
816 if (compressed) {
817 split->block_len = em->block_len;
818 split->orig_start = em->orig_start;
819 } else {
820 const u64 diff = end - em->start;
821
822 split->block_len = split->len;
823 split->block_start += diff;
824 split->orig_start = em->orig_start;
825 }
826 } else {
827 split->ram_bytes = split->len;
828 split->orig_start = split->start;
829 split->block_len = 0;
830 split->orig_block_len = 0;
831 }
832
833 if (extent_map_in_tree(em)) {
834 replace_extent_mapping(em_tree, em, split,
835 modified);
836 } else {
837 int ret;
838
839 ret = add_extent_mapping(em_tree, split,
840 modified);
841 /* Logic error, shouldn't happen. */
842 ASSERT(ret == 0);
843 if (WARN_ON(ret != 0) && modified)
844 btrfs_set_inode_full_sync(inode);
845 }
846 free_extent_map(split);
847 split = NULL;
848 }
849remove_em:
850 if (extent_map_in_tree(em)) {
851 /*
852 * If the extent map is still in the tree it means that
853 * either of the following is true:
854 *
855 * 1) It fits entirely in our range (doesn't end beyond
856 * it or starts before it);
857 *
858 * 2) It starts before our range and/or ends after our
859 * range, and we were not able to allocate the extent
860 * maps for split operations, @split and @split2.
861 *
862 * If we are at case 2) then we just remove the entire
863 * extent map - this is fine since if anyone needs it to
864 * access the subranges outside our range, will just
865 * load it again from the subvolume tree's file extent
866 * item. However if the extent map was in the list of
867 * modified extents, then we must mark the inode for a
868 * full fsync, otherwise a fast fsync will miss this
869 * extent if it's new and needs to be logged.
870 */
871 if ((em->start < start || em_end > end) && modified) {
872 ASSERT(!split);
873 btrfs_set_inode_full_sync(inode);
874 }
875 remove_extent_mapping(em_tree, em);
876 }
877
878 /*
879 * Once for the tree reference (we replaced or removed the
880 * extent map from the tree).
881 */
882 free_extent_map(em);
883next:
884 /* Once for us (for our lookup reference). */
885 free_extent_map(em);
886
887 em = next_em;
888 }
889
890 write_unlock(&em_tree->lock);
891
892 free_extent_map(split);
893 free_extent_map(split2);
894}
895
896/*
897 * Replace a range in the inode's extent map tree with a new extent map.
898 *
899 * @inode: The target inode.
900 * @new_em: The new extent map to add to the inode's extent map tree.
901 * @modified: Indicate if the new extent map should be added to the list of
902 * modified extents (for fast fsync tracking).
903 *
904 * Drops all the extent maps in the inode's extent map tree that intersect the
905 * range of the new extent map and adds the new extent map to the tree.
906 * The caller should have locked an appropriate file range in the inode's io
907 * tree before calling this function.
908 */
909int btrfs_replace_extent_map_range(struct btrfs_inode *inode,
910 struct extent_map *new_em,
911 bool modified)
912{
913 const u64 end = new_em->start + new_em->len - 1;
914 struct extent_map_tree *tree = &inode->extent_tree;
915 int ret;
916
917 ASSERT(!extent_map_in_tree(new_em));
918
919 /*
920 * The caller has locked an appropriate file range in the inode's io
921 * tree, but getting -EEXIST when adding the new extent map can still
922 * happen in case there are extents that partially cover the range, and
923 * this is due to two tasks operating on different parts of the extent.
924 * See commit 18e83ac75bfe67 ("Btrfs: fix unexpected EEXIST from
925 * btrfs_get_extent") for an example and details.
926 */
927 do {
928 btrfs_drop_extent_map_range(inode, new_em->start, end, false);
929 write_lock(&tree->lock);
930 ret = add_extent_mapping(tree, new_em, modified);
931 write_unlock(&tree->lock);
932 } while (ret == -EEXIST);
933
934 return ret;
935}
936
937/*
938 * Split off the first pre bytes from the extent_map at [start, start + len],
939 * and set the block_start for it to new_logical.
940 *
941 * This function is used when an ordered_extent needs to be split.
942 */
943int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
944 u64 new_logical)
945{
946 struct extent_map_tree *em_tree = &inode->extent_tree;
947 struct extent_map *em;
948 struct extent_map *split_pre = NULL;
949 struct extent_map *split_mid = NULL;
950 int ret = 0;
951 unsigned long flags;
952
953 ASSERT(pre != 0);
954 ASSERT(pre < len);
955
956 split_pre = alloc_extent_map();
957 if (!split_pre)
958 return -ENOMEM;
959 split_mid = alloc_extent_map();
960 if (!split_mid) {
961 ret = -ENOMEM;
962 goto out_free_pre;
963 }
964
965 lock_extent(&inode->io_tree, start, start + len - 1, NULL);
966 write_lock(&em_tree->lock);
967 em = lookup_extent_mapping(em_tree, start, len);
968 if (!em) {
969 ret = -EIO;
970 goto out_unlock;
971 }
972
973 ASSERT(em->len == len);
974 ASSERT(!extent_map_is_compressed(em));
975 ASSERT(em->block_start < EXTENT_MAP_LAST_BYTE);
976 ASSERT(em->flags & EXTENT_FLAG_PINNED);
977 ASSERT(!(em->flags & EXTENT_FLAG_LOGGING));
978 ASSERT(!list_empty(&em->list));
979
980 flags = em->flags;
981 em->flags &= ~EXTENT_FLAG_PINNED;
982
983 /* First, replace the em with a new extent_map starting from * em->start */
984 split_pre->start = em->start;
985 split_pre->len = pre;
986 split_pre->orig_start = split_pre->start;
987 split_pre->block_start = new_logical;
988 split_pre->block_len = split_pre->len;
989 split_pre->orig_block_len = split_pre->block_len;
990 split_pre->ram_bytes = split_pre->len;
991 split_pre->flags = flags;
992 split_pre->generation = em->generation;
993
994 replace_extent_mapping(em_tree, em, split_pre, 1);
995
996 /*
997 * Now we only have an extent_map at:
998 * [em->start, em->start + pre]
999 */
1000
1001 /* Insert the middle extent_map. */
1002 split_mid->start = em->start + pre;
1003 split_mid->len = em->len - pre;
1004 split_mid->orig_start = split_mid->start;
1005 split_mid->block_start = em->block_start + pre;
1006 split_mid->block_len = split_mid->len;
1007 split_mid->orig_block_len = split_mid->block_len;
1008 split_mid->ram_bytes = split_mid->len;
1009 split_mid->flags = flags;
1010 split_mid->generation = em->generation;
1011 add_extent_mapping(em_tree, split_mid, 1);
1012
1013 /* Once for us */
1014 free_extent_map(em);
1015 /* Once for the tree */
1016 free_extent_map(em);
1017
1018out_unlock:
1019 write_unlock(&em_tree->lock);
1020 unlock_extent(&inode->io_tree, start, start + len - 1, NULL);
1021 free_extent_map(split_mid);
1022out_free_pre:
1023 free_extent_map(split_pre);
1024 return ret;
1025}