1 // SPDX-License-Identifier: GPL-2.0
4 #include <linux/slab.h>
5 #include <linux/spinlock.h>
7 #include "extent_map.h"
8 #include "compression.h"
11 static struct kmem_cache *extent_map_cache;
13 int __init extent_map_init(void)
15 extent_map_cache = kmem_cache_create("btrfs_extent_map",
16 sizeof(struct extent_map), 0,
17 SLAB_MEM_SPREAD, NULL);
18 if (!extent_map_cache)
23 void __cold extent_map_exit(void)
25 kmem_cache_destroy(extent_map_cache);
29 * extent_map_tree_init - initialize extent map tree
30 * @tree: tree to initialize
32 * Initialize the extent tree @tree. Should be called for each new inode
33 * or other user of the extent_map interface.
35 void extent_map_tree_init(struct extent_map_tree *tree)
37 tree->map = RB_ROOT_CACHED;
38 INIT_LIST_HEAD(&tree->modified_extents);
39 rwlock_init(&tree->lock);
43 * alloc_extent_map - allocate new extent map structure
45 * Allocate a new extent_map structure. The new structure is
46 * returned with a reference count of one and needs to be
47 * freed using free_extent_map()
49 struct extent_map *alloc_extent_map(void)
51 struct extent_map *em;
52 em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
55 RB_CLEAR_NODE(&em->rb_node);
57 em->compress_type = BTRFS_COMPRESS_NONE;
59 refcount_set(&em->refs, 1);
60 INIT_LIST_HEAD(&em->list);
65 * free_extent_map - drop reference count of an extent_map
66 * @em: extent map being released
68 * Drops the reference out on @em by one and free the structure
69 * if the reference count hits zero.
71 void free_extent_map(struct extent_map *em)
75 WARN_ON(refcount_read(&em->refs) == 0);
76 if (refcount_dec_and_test(&em->refs)) {
77 WARN_ON(extent_map_in_tree(em));
78 WARN_ON(!list_empty(&em->list));
79 if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags))
80 kfree(em->map_lookup);
81 kmem_cache_free(extent_map_cache, em);
85 /* simple helper to do math around the end of an extent, handling wrap */
86 static u64 range_end(u64 start, u64 len)
88 if (start + len < start)
93 static int tree_insert(struct rb_root_cached *root, struct extent_map *em)
95 struct rb_node **p = &root->rb_root.rb_node;
96 struct rb_node *parent = NULL;
97 struct extent_map *entry = NULL;
98 struct rb_node *orig_parent = NULL;
99 u64 end = range_end(em->start, em->len);
100 bool leftmost = true;
104 entry = rb_entry(parent, struct extent_map, rb_node);
106 if (em->start < entry->start) {
108 } else if (em->start >= extent_map_end(entry)) {
116 orig_parent = parent;
117 while (parent && em->start >= extent_map_end(entry)) {
118 parent = rb_next(parent);
119 entry = rb_entry(parent, struct extent_map, rb_node);
122 if (end > entry->start && em->start < extent_map_end(entry))
125 parent = orig_parent;
126 entry = rb_entry(parent, struct extent_map, rb_node);
127 while (parent && em->start < entry->start) {
128 parent = rb_prev(parent);
129 entry = rb_entry(parent, struct extent_map, rb_node);
132 if (end > entry->start && em->start < extent_map_end(entry))
135 rb_link_node(&em->rb_node, orig_parent, p);
136 rb_insert_color_cached(&em->rb_node, root, leftmost);
141 * search through the tree for an extent_map with a given offset. If
142 * it can't be found, try to find some neighboring extents
144 static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
145 struct rb_node **prev_ret,
146 struct rb_node **next_ret)
148 struct rb_node *n = root->rb_node;
149 struct rb_node *prev = NULL;
150 struct rb_node *orig_prev = NULL;
151 struct extent_map *entry;
152 struct extent_map *prev_entry = NULL;
155 entry = rb_entry(n, struct extent_map, rb_node);
159 if (offset < entry->start)
161 else if (offset >= extent_map_end(entry))
169 while (prev && offset >= extent_map_end(prev_entry)) {
170 prev = rb_next(prev);
171 prev_entry = rb_entry(prev, struct extent_map, rb_node);
178 prev_entry = rb_entry(prev, struct extent_map, rb_node);
179 while (prev && offset < prev_entry->start) {
180 prev = rb_prev(prev);
181 prev_entry = rb_entry(prev, struct extent_map, rb_node);
188 /* check to see if two extent_map structs are adjacent and safe to merge */
189 static int mergable_maps(struct extent_map *prev, struct extent_map *next)
191 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
195 * don't merge compressed extents, we need to know their
198 if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
201 if (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) ||
202 test_bit(EXTENT_FLAG_LOGGING, &next->flags))
206 * We don't want to merge stuff that hasn't been written to the log yet
207 * since it may not reflect exactly what is on disk, and that would be
210 if (!list_empty(&prev->list) || !list_empty(&next->list))
213 ASSERT(next->block_start != EXTENT_MAP_DELALLOC &&
214 prev->block_start != EXTENT_MAP_DELALLOC);
216 if (extent_map_end(prev) == next->start &&
217 prev->flags == next->flags &&
218 prev->bdev == next->bdev &&
219 ((next->block_start == EXTENT_MAP_HOLE &&
220 prev->block_start == EXTENT_MAP_HOLE) ||
221 (next->block_start == EXTENT_MAP_INLINE &&
222 prev->block_start == EXTENT_MAP_INLINE) ||
223 (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
224 next->block_start == extent_map_block_end(prev)))) {
230 static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
232 struct extent_map *merge = NULL;
235 if (em->start != 0) {
236 rb = rb_prev(&em->rb_node);
238 merge = rb_entry(rb, struct extent_map, rb_node);
239 if (rb && mergable_maps(merge, em)) {
240 em->start = merge->start;
241 em->orig_start = merge->orig_start;
242 em->len += merge->len;
243 em->block_len += merge->block_len;
244 em->block_start = merge->block_start;
245 em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
246 em->mod_start = merge->mod_start;
247 em->generation = max(em->generation, merge->generation);
249 rb_erase_cached(&merge->rb_node, &tree->map);
250 RB_CLEAR_NODE(&merge->rb_node);
251 free_extent_map(merge);
255 rb = rb_next(&em->rb_node);
257 merge = rb_entry(rb, struct extent_map, rb_node);
258 if (rb && mergable_maps(em, merge)) {
259 em->len += merge->len;
260 em->block_len += merge->block_len;
261 rb_erase_cached(&merge->rb_node, &tree->map);
262 RB_CLEAR_NODE(&merge->rb_node);
263 em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
264 em->generation = max(em->generation, merge->generation);
265 free_extent_map(merge);
270 * unpin_extent_cache - unpin an extent from the cache
271 * @tree: tree to unpin the extent in
272 * @start: logical offset in the file
273 * @len: length of the extent
274 * @gen: generation that this extent has been modified in
276 * Called after an extent has been written to disk properly. Set the generation
277 * to the generation that actually added the file item to the inode so we know
278 * we need to sync this extent when we call fsync().
280 int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
284 struct extent_map *em;
285 bool prealloc = false;
287 write_lock(&tree->lock);
288 em = lookup_extent_mapping(tree, start, len);
290 WARN_ON(!em || em->start != start);
295 em->generation = gen;
296 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
297 em->mod_start = em->start;
298 em->mod_len = em->len;
300 if (test_bit(EXTENT_FLAG_FILLING, &em->flags)) {
302 clear_bit(EXTENT_FLAG_FILLING, &em->flags);
305 try_merge_map(tree, em);
308 em->mod_start = em->start;
309 em->mod_len = em->len;
314 write_unlock(&tree->lock);
319 void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
321 clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
322 if (extent_map_in_tree(em))
323 try_merge_map(tree, em);
326 static inline void setup_extent_mapping(struct extent_map_tree *tree,
327 struct extent_map *em,
330 refcount_inc(&em->refs);
331 em->mod_start = em->start;
332 em->mod_len = em->len;
335 list_move(&em->list, &tree->modified_extents);
337 try_merge_map(tree, em);
341 * add_extent_mapping - add new extent map to the extent tree
342 * @tree: tree to insert new map in
345 * Insert @em into @tree or perform a simple forward/backward merge with
346 * existing mappings. The extent_map struct passed in will be inserted
347 * into the tree directly, with an additional reference taken, or a
348 * reference dropped if the merge attempt was successful.
350 int add_extent_mapping(struct extent_map_tree *tree,
351 struct extent_map *em, int modified)
355 ret = tree_insert(&tree->map, em);
359 setup_extent_mapping(tree, em, modified);
364 static struct extent_map *
365 __lookup_extent_mapping(struct extent_map_tree *tree,
366 u64 start, u64 len, int strict)
368 struct extent_map *em;
369 struct rb_node *rb_node;
370 struct rb_node *prev = NULL;
371 struct rb_node *next = NULL;
372 u64 end = range_end(start, len);
374 rb_node = __tree_search(&tree->map.rb_root, start, &prev, &next);
384 em = rb_entry(rb_node, struct extent_map, rb_node);
386 if (strict && !(end > em->start && start < extent_map_end(em)))
389 refcount_inc(&em->refs);
394 * lookup_extent_mapping - lookup extent_map
395 * @tree: tree to lookup in
396 * @start: byte offset to start the search
397 * @len: length of the lookup range
399 * Find and return the first extent_map struct in @tree that intersects the
400 * [start, len] range. There may be additional objects in the tree that
401 * intersect, so check the object returned carefully to make sure that no
402 * additional lookups are needed.
404 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
407 return __lookup_extent_mapping(tree, start, len, 1);
411 * search_extent_mapping - find a nearby extent map
412 * @tree: tree to lookup in
413 * @start: byte offset to start the search
414 * @len: length of the lookup range
416 * Find and return the first extent_map struct in @tree that intersects the
417 * [start, len] range.
419 * If one can't be found, any nearby extent may be returned
421 struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
424 return __lookup_extent_mapping(tree, start, len, 0);
428 * remove_extent_mapping - removes an extent_map from the extent tree
429 * @tree: extent tree to remove from
430 * @em: extent map being removed
432 * Removes @em from @tree. No reference counts are dropped, and no checks
433 * are done to see if the range is in use
435 void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
437 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
438 rb_erase_cached(&em->rb_node, &tree->map);
439 if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
440 list_del_init(&em->list);
441 RB_CLEAR_NODE(&em->rb_node);
444 void replace_extent_mapping(struct extent_map_tree *tree,
445 struct extent_map *cur,
446 struct extent_map *new,
449 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags));
450 ASSERT(extent_map_in_tree(cur));
451 if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags))
452 list_del_init(&cur->list);
453 rb_replace_node_cached(&cur->rb_node, &new->rb_node, &tree->map);
454 RB_CLEAR_NODE(&cur->rb_node);
456 setup_extent_mapping(tree, new, modified);
459 static struct extent_map *next_extent_map(struct extent_map *em)
461 struct rb_node *next;
463 next = rb_next(&em->rb_node);
466 return container_of(next, struct extent_map, rb_node);
469 static struct extent_map *prev_extent_map(struct extent_map *em)
471 struct rb_node *prev;
473 prev = rb_prev(&em->rb_node);
476 return container_of(prev, struct extent_map, rb_node);
480 * Helper for btrfs_get_extent. Given an existing extent in the tree,
481 * the existing extent is the nearest extent to map_start,
482 * and an extent that you want to insert, deal with overlap and insert
483 * the best fitted new extent into the tree.
485 static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
486 struct extent_map *existing,
487 struct extent_map *em,
490 struct extent_map *prev;
491 struct extent_map *next;
496 BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
498 if (existing->start > map_start) {
500 prev = prev_extent_map(next);
503 next = next_extent_map(prev);
506 start = prev ? extent_map_end(prev) : em->start;
507 start = max_t(u64, start, em->start);
508 end = next ? next->start : extent_map_end(em);
509 end = min_t(u64, end, extent_map_end(em));
510 start_diff = start - em->start;
512 em->len = end - start;
513 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
514 !test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
515 em->block_start += start_diff;
516 em->block_len = em->len;
518 return add_extent_mapping(em_tree, em, 0);
522 * btrfs_add_extent_mapping - add extent mapping into em_tree
523 * @fs_info - used for tracepoint
524 * @em_tree - the extent tree into which we want to insert the extent mapping
525 * @em_in - extent we are inserting
526 * @start - start of the logical range btrfs_get_extent() is requesting
527 * @len - length of the logical range btrfs_get_extent() is requesting
529 * Note that @em_in's range may be different from [start, start+len),
530 * but they must be overlapped.
532 * Insert @em_in into @em_tree. In case there is an overlapping range, handle
533 * the -EEXIST by either:
534 * a) Returning the existing extent in @em_in if @start is within the
536 * b) Merge the existing extent with @em_in passed in.
538 * Return 0 on success, otherwise -EEXIST.
541 int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
542 struct extent_map_tree *em_tree,
543 struct extent_map **em_in, u64 start, u64 len)
546 struct extent_map *em = *em_in;
548 ret = add_extent_mapping(em_tree, em, 0);
549 /* it is possible that someone inserted the extent into the tree
550 * while we had the lock dropped. It is also possible that
551 * an overlapping map exists in the tree
553 if (ret == -EEXIST) {
554 struct extent_map *existing;
558 existing = search_extent_mapping(em_tree, start, len);
560 trace_btrfs_handle_em_exist(fs_info, existing, em, start, len);
563 * existing will always be non-NULL, since there must be
564 * extent causing the -EEXIST.
566 if (start >= existing->start &&
567 start < extent_map_end(existing)) {
572 u64 orig_start = em->start;
573 u64 orig_len = em->len;
576 * The existing extent map is the one nearest to
577 * the [start, start + len) range which overlaps
579 ret = merge_extent_mapping(em_tree, existing,
585 "unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
586 ret, existing->start, existing->len,
587 orig_start, orig_len);
589 free_extent_map(existing);
593 ASSERT(ret == 0 || ret == -EEXIST);