2 #include <linux/slab.h>
3 #include <linux/spinlock.h>
4 #include <linux/hardirq.h>
6 #include "extent_map.h"
9 static struct kmem_cache *extent_map_cache;
11 int __init extent_map_init(void)
13 extent_map_cache = kmem_cache_create("btrfs_extent_map",
14 sizeof(struct extent_map), 0,
15 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
16 if (!extent_map_cache)
21 void extent_map_exit(void)
24 kmem_cache_destroy(extent_map_cache);
28 * extent_map_tree_init - initialize extent map tree
29 * @tree: tree to initialize
31 * Initialize the extent tree @tree. Should be called for each new inode
32 * or other user of the extent_map interface.
34 void extent_map_tree_init(struct extent_map_tree *tree)
37 INIT_LIST_HEAD(&tree->modified_extents);
38 rwlock_init(&tree->lock);
42 * alloc_extent_map - allocate new extent map structure
44 * Allocate a new extent_map structure. The new structure is
45 * returned with a reference count of one and needs to be
46 * freed using free_extent_map()
48 struct extent_map *alloc_extent_map(void)
50 struct extent_map *em;
51 em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
56 em->compress_type = BTRFS_COMPRESS_NONE;
58 atomic_set(&em->refs, 1);
59 INIT_LIST_HEAD(&em->list);
64 * free_extent_map - drop reference count of an extent_map
65 * @em: extent map beeing releasead
67 * Drops the reference out on @em by one and free the structure
68 * if the reference count hits zero.
70 void free_extent_map(struct extent_map *em)
74 WARN_ON(atomic_read(&em->refs) == 0);
75 if (atomic_dec_and_test(&em->refs)) {
77 WARN_ON(!list_empty(&em->list));
78 kmem_cache_free(extent_map_cache, em);
82 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
85 struct rb_node **p = &root->rb_node;
86 struct rb_node *parent = NULL;
87 struct extent_map *entry;
91 entry = rb_entry(parent, struct extent_map, rb_node);
93 WARN_ON(!entry->in_tree);
95 if (offset < entry->start)
97 else if (offset >= extent_map_end(entry))
103 entry = rb_entry(node, struct extent_map, rb_node);
105 rb_link_node(node, parent, p);
106 rb_insert_color(node, root);
111 * search through the tree for an extent_map with a given offset. If
112 * it can't be found, try to find some neighboring extents
114 static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
115 struct rb_node **prev_ret,
116 struct rb_node **next_ret)
118 struct rb_node *n = root->rb_node;
119 struct rb_node *prev = NULL;
120 struct rb_node *orig_prev = NULL;
121 struct extent_map *entry;
122 struct extent_map *prev_entry = NULL;
125 entry = rb_entry(n, struct extent_map, rb_node);
129 WARN_ON(!entry->in_tree);
131 if (offset < entry->start)
133 else if (offset >= extent_map_end(entry))
141 while (prev && offset >= extent_map_end(prev_entry)) {
142 prev = rb_next(prev);
143 prev_entry = rb_entry(prev, struct extent_map, rb_node);
150 prev_entry = rb_entry(prev, struct extent_map, rb_node);
151 while (prev && offset < prev_entry->start) {
152 prev = rb_prev(prev);
153 prev_entry = rb_entry(prev, struct extent_map, rb_node);
160 /* check to see if two extent_map structs are adjacent and safe to merge */
161 static int mergable_maps(struct extent_map *prev, struct extent_map *next)
163 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
167 * don't merge compressed extents, we need to know their
170 if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
173 if (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) ||
174 test_bit(EXTENT_FLAG_LOGGING, &next->flags))
177 if (extent_map_end(prev) == next->start &&
178 prev->flags == next->flags &&
179 prev->bdev == next->bdev &&
180 ((next->block_start == EXTENT_MAP_HOLE &&
181 prev->block_start == EXTENT_MAP_HOLE) ||
182 (next->block_start == EXTENT_MAP_INLINE &&
183 prev->block_start == EXTENT_MAP_INLINE) ||
184 (next->block_start == EXTENT_MAP_DELALLOC &&
185 prev->block_start == EXTENT_MAP_DELALLOC) ||
186 (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
187 next->block_start == extent_map_block_end(prev)))) {
193 static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
195 struct extent_map *merge = NULL;
198 if (em->start != 0) {
199 rb = rb_prev(&em->rb_node);
201 merge = rb_entry(rb, struct extent_map, rb_node);
202 if (rb && mergable_maps(merge, em)) {
203 em->start = merge->start;
204 em->orig_start = merge->orig_start;
205 em->len += merge->len;
206 em->block_len += merge->block_len;
207 em->block_start = merge->block_start;
209 em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
210 em->mod_start = merge->mod_start;
211 em->generation = max(em->generation, merge->generation);
212 list_move(&em->list, &tree->modified_extents);
214 list_del_init(&merge->list);
215 rb_erase(&merge->rb_node, &tree->map);
216 free_extent_map(merge);
220 rb = rb_next(&em->rb_node);
222 merge = rb_entry(rb, struct extent_map, rb_node);
223 if (rb && mergable_maps(em, merge)) {
224 em->len += merge->len;
225 em->block_len += merge->len;
226 rb_erase(&merge->rb_node, &tree->map);
228 em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
229 em->generation = max(em->generation, merge->generation);
230 list_del_init(&merge->list);
231 free_extent_map(merge);
236 * unpin_extent_cache - unpin an extent from the cache
237 * @tree: tree to unpin the extent in
238 * @start: logical offset in the file
239 * @len: length of the extent
240 * @gen: generation that this extent has been modified in
242 * Called after an extent has been written to disk properly. Set the generation
243 * to the generation that actually added the file item to the inode so we know
244 * we need to sync this extent when we call fsync().
246 int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
250 struct extent_map *em;
251 bool prealloc = false;
253 write_lock(&tree->lock);
254 em = lookup_extent_mapping(tree, start, len);
256 WARN_ON(!em || em->start != start);
261 if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
262 list_move(&em->list, &tree->modified_extents);
263 em->generation = gen;
264 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
265 em->mod_start = em->start;
266 em->mod_len = em->len;
268 if (test_bit(EXTENT_FLAG_FILLING, &em->flags)) {
270 clear_bit(EXTENT_FLAG_FILLING, &em->flags);
273 try_merge_map(tree, em);
276 em->mod_start = em->start;
277 em->mod_len = em->len;
282 write_unlock(&tree->lock);
287 void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
289 clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
291 try_merge_map(tree, em);
295 * add_extent_mapping - add new extent map to the extent tree
296 * @tree: tree to insert new map in
299 * Insert @em into @tree or perform a simple forward/backward merge with
300 * existing mappings. The extent_map struct passed in will be inserted
301 * into the tree directly, with an additional reference taken, or a
302 * reference dropped if the merge attempt was successful.
304 int add_extent_mapping(struct extent_map_tree *tree,
305 struct extent_map *em)
309 struct extent_map *exist;
311 exist = lookup_extent_mapping(tree, em->start, em->len);
313 free_extent_map(exist);
317 rb = tree_insert(&tree->map, em->start, &em->rb_node);
322 atomic_inc(&em->refs);
324 em->mod_start = em->start;
325 em->mod_len = em->len;
327 try_merge_map(tree, em);
332 /* simple helper to do math around the end of an extent, handling wrap */
333 static u64 range_end(u64 start, u64 len)
335 if (start + len < start)
340 struct extent_map *__lookup_extent_mapping(struct extent_map_tree *tree,
341 u64 start, u64 len, int strict)
343 struct extent_map *em;
344 struct rb_node *rb_node;
345 struct rb_node *prev = NULL;
346 struct rb_node *next = NULL;
347 u64 end = range_end(start, len);
349 rb_node = __tree_search(&tree->map, start, &prev, &next);
359 em = rb_entry(rb_node, struct extent_map, rb_node);
361 if (strict && !(end > em->start && start < extent_map_end(em)))
364 atomic_inc(&em->refs);
369 * lookup_extent_mapping - lookup extent_map
370 * @tree: tree to lookup in
371 * @start: byte offset to start the search
372 * @len: length of the lookup range
374 * Find and return the first extent_map struct in @tree that intersects the
375 * [start, len] range. There may be additional objects in the tree that
376 * intersect, so check the object returned carefully to make sure that no
377 * additional lookups are needed.
379 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
382 return __lookup_extent_mapping(tree, start, len, 1);
386 * search_extent_mapping - find a nearby extent map
387 * @tree: tree to lookup in
388 * @start: byte offset to start the search
389 * @len: length of the lookup range
391 * Find and return the first extent_map struct in @tree that intersects the
392 * [start, len] range.
394 * If one can't be found, any nearby extent may be returned
396 struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
399 return __lookup_extent_mapping(tree, start, len, 0);
403 * remove_extent_mapping - removes an extent_map from the extent tree
404 * @tree: extent tree to remove from
405 * @em: extent map beeing removed
407 * Removes @em from @tree. No reference counts are dropped, and no checks
408 * are done to see if the range is in use
410 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
414 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
415 rb_erase(&em->rb_node, &tree->map);
416 if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
417 list_del_init(&em->list);