2 #include <linux/slab.h>
3 #include <linux/module.h>
4 #include <linux/spinlock.h>
5 #include <linux/hardirq.h>
7 #include "extent_map.h"
10 static struct kmem_cache
*extent_map_cache
;
12 int __init
extent_map_init(void)
14 extent_map_cache
= kmem_cache_create("btrfs_extent_map",
15 sizeof(struct extent_map
), 0,
16 SLAB_RECLAIM_ACCOUNT
| SLAB_MEM_SPREAD
, NULL
);
17 if (!extent_map_cache
)
22 void 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
)
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_alloc(extent_map_cache
, GFP_NOFS
);
57 em
->compress_type
= BTRFS_COMPRESS_NONE
;
59 atomic_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 beeing releasead
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(atomic_read(&em
->refs
) == 0);
76 if (atomic_dec_and_test(&em
->refs
)) {
78 WARN_ON(!list_empty(&em
->list
));
79 kmem_cache_free(extent_map_cache
, em
);
83 static struct rb_node
*tree_insert(struct rb_root
*root
, u64 offset
,
86 struct rb_node
**p
= &root
->rb_node
;
87 struct rb_node
*parent
= NULL
;
88 struct extent_map
*entry
;
92 entry
= rb_entry(parent
, struct extent_map
, rb_node
);
94 WARN_ON(!entry
->in_tree
);
96 if (offset
< entry
->start
)
98 else if (offset
>= extent_map_end(entry
))
104 entry
= rb_entry(node
, struct extent_map
, rb_node
);
106 rb_link_node(node
, parent
, p
);
107 rb_insert_color(node
, root
);
112 * search through the tree for an extent_map with a given offset. If
113 * it can't be found, try to find some neighboring extents
115 static struct rb_node
*__tree_search(struct rb_root
*root
, u64 offset
,
116 struct rb_node
**prev_ret
,
117 struct rb_node
**next_ret
)
119 struct rb_node
*n
= root
->rb_node
;
120 struct rb_node
*prev
= NULL
;
121 struct rb_node
*orig_prev
= NULL
;
122 struct extent_map
*entry
;
123 struct extent_map
*prev_entry
= NULL
;
126 entry
= rb_entry(n
, struct extent_map
, rb_node
);
130 WARN_ON(!entry
->in_tree
);
132 if (offset
< entry
->start
)
134 else if (offset
>= extent_map_end(entry
))
142 while (prev
&& offset
>= extent_map_end(prev_entry
)) {
143 prev
= rb_next(prev
);
144 prev_entry
= rb_entry(prev
, struct extent_map
, rb_node
);
151 prev_entry
= rb_entry(prev
, struct extent_map
, rb_node
);
152 while (prev
&& offset
< prev_entry
->start
) {
153 prev
= rb_prev(prev
);
154 prev_entry
= rb_entry(prev
, struct extent_map
, rb_node
);
161 /* check to see if two extent_map structs are adjacent and safe to merge */
162 static int mergable_maps(struct extent_map
*prev
, struct extent_map
*next
)
164 if (test_bit(EXTENT_FLAG_PINNED
, &prev
->flags
))
168 * don't merge compressed extents, we need to know their
171 if (test_bit(EXTENT_FLAG_COMPRESSED
, &prev
->flags
))
174 if (extent_map_end(prev
) == next
->start
&&
175 prev
->flags
== next
->flags
&&
176 prev
->bdev
== next
->bdev
&&
177 ((next
->block_start
== EXTENT_MAP_HOLE
&&
178 prev
->block_start
== EXTENT_MAP_HOLE
) ||
179 (next
->block_start
== EXTENT_MAP_INLINE
&&
180 prev
->block_start
== EXTENT_MAP_INLINE
) ||
181 (next
->block_start
== EXTENT_MAP_DELALLOC
&&
182 prev
->block_start
== EXTENT_MAP_DELALLOC
) ||
183 (next
->block_start
< EXTENT_MAP_LAST_BYTE
- 1 &&
184 next
->block_start
== extent_map_block_end(prev
)))) {
190 static void try_merge_map(struct extent_map_tree
*tree
, struct extent_map
*em
)
192 struct extent_map
*merge
= NULL
;
195 if (em
->start
!= 0) {
196 rb
= rb_prev(&em
->rb_node
);
198 merge
= rb_entry(rb
, struct extent_map
, rb_node
);
199 if (rb
&& mergable_maps(merge
, em
)) {
200 em
->start
= merge
->start
;
201 em
->len
+= merge
->len
;
202 em
->block_len
+= merge
->block_len
;
203 em
->block_start
= merge
->block_start
;
205 if (merge
->generation
> em
->generation
) {
206 em
->mod_start
= em
->start
;
207 em
->mod_len
= em
->len
;
208 em
->generation
= merge
->generation
;
209 list_move(&em
->list
, &tree
->modified_extents
);
212 list_del_init(&merge
->list
);
213 rb_erase(&merge
->rb_node
, &tree
->map
);
214 free_extent_map(merge
);
218 rb
= rb_next(&em
->rb_node
);
220 merge
= rb_entry(rb
, struct extent_map
, rb_node
);
221 if (rb
&& mergable_maps(em
, merge
)) {
222 em
->len
+= merge
->len
;
223 em
->block_len
+= merge
->len
;
224 rb_erase(&merge
->rb_node
, &tree
->map
);
226 if (merge
->generation
> em
->generation
) {
227 em
->mod_len
= em
->len
;
228 em
->generation
= merge
->generation
;
229 list_move(&em
->list
, &tree
->modified_extents
);
231 list_del_init(&merge
->list
);
232 free_extent_map(merge
);
237 * unpint_extent_cache - unpin an extent from the cache
238 * @tree: tree to unpin the extent in
239 * @start: logical offset in the file
240 * @len: length of the extent
241 * @gen: generation that this extent has been modified in
242 * @prealloc: if this is set we need to clear the prealloc flag
244 * Called after an extent has been written to disk properly. Set the generation
245 * to the generation that actually added the file item to the inode so we know
246 * we need to sync this extent when we call fsync().
248 int unpin_extent_cache(struct extent_map_tree
*tree
, u64 start
, u64 len
,
252 struct extent_map
*em
;
253 bool prealloc
= false;
255 write_lock(&tree
->lock
);
256 em
= lookup_extent_mapping(tree
, start
, len
);
258 WARN_ON(!em
|| em
->start
!= start
);
263 list_move(&em
->list
, &tree
->modified_extents
);
264 em
->generation
= gen
;
265 clear_bit(EXTENT_FLAG_PINNED
, &em
->flags
);
266 em
->mod_start
= em
->start
;
267 em
->mod_len
= em
->len
;
269 if (test_bit(EXTENT_FLAG_FILLING
, &em
->flags
)) {
271 clear_bit(EXTENT_FLAG_FILLING
, &em
->flags
);
274 try_merge_map(tree
, em
);
277 em
->mod_start
= em
->start
;
278 em
->mod_len
= em
->len
;
283 write_unlock(&tree
->lock
);
289 * add_extent_mapping - add new extent map to the extent tree
290 * @tree: tree to insert new map in
293 * Insert @em into @tree or perform a simple forward/backward merge with
294 * existing mappings. The extent_map struct passed in will be inserted
295 * into the tree directly, with an additional reference taken, or a
296 * reference dropped if the merge attempt was successful.
298 int add_extent_mapping(struct extent_map_tree
*tree
,
299 struct extent_map
*em
)
303 struct extent_map
*exist
;
305 exist
= lookup_extent_mapping(tree
, em
->start
, em
->len
);
307 free_extent_map(exist
);
311 rb
= tree_insert(&tree
->map
, em
->start
, &em
->rb_node
);
316 atomic_inc(&em
->refs
);
318 em
->mod_start
= em
->start
;
319 em
->mod_len
= em
->len
;
321 try_merge_map(tree
, em
);
326 /* simple helper to do math around the end of an extent, handling wrap */
327 static u64
range_end(u64 start
, u64 len
)
329 if (start
+ len
< start
)
334 struct extent_map
*__lookup_extent_mapping(struct extent_map_tree
*tree
,
335 u64 start
, u64 len
, int strict
)
337 struct extent_map
*em
;
338 struct rb_node
*rb_node
;
339 struct rb_node
*prev
= NULL
;
340 struct rb_node
*next
= NULL
;
341 u64 end
= range_end(start
, len
);
343 rb_node
= __tree_search(&tree
->map
, start
, &prev
, &next
);
353 em
= rb_entry(rb_node
, struct extent_map
, rb_node
);
355 if (strict
&& !(end
> em
->start
&& start
< extent_map_end(em
)))
358 atomic_inc(&em
->refs
);
363 * lookup_extent_mapping - lookup extent_map
364 * @tree: tree to lookup in
365 * @start: byte offset to start the search
366 * @len: length of the lookup range
368 * Find and return the first extent_map struct in @tree that intersects the
369 * [start, len] range. There may be additional objects in the tree that
370 * intersect, so check the object returned carefully to make sure that no
371 * additional lookups are needed.
373 struct extent_map
*lookup_extent_mapping(struct extent_map_tree
*tree
,
376 return __lookup_extent_mapping(tree
, start
, len
, 1);
380 * search_extent_mapping - find a nearby extent map
381 * @tree: tree to lookup in
382 * @start: byte offset to start the search
383 * @len: length of the lookup range
385 * Find and return the first extent_map struct in @tree that intersects the
386 * [start, len] range.
388 * If one can't be found, any nearby extent may be returned
390 struct extent_map
*search_extent_mapping(struct extent_map_tree
*tree
,
393 return __lookup_extent_mapping(tree
, start
, len
, 0);
397 * remove_extent_mapping - removes an extent_map from the extent tree
398 * @tree: extent tree to remove from
399 * @em: extent map beeing removed
401 * Removes @em from @tree. No reference counts are dropped, and no checks
402 * are done to see if the range is in use
404 int remove_extent_mapping(struct extent_map_tree
*tree
, struct extent_map
*em
)
408 WARN_ON(test_bit(EXTENT_FLAG_PINNED
, &em
->flags
));
409 rb_erase(&em
->rb_node
, &tree
->map
);
410 if (!test_bit(EXTENT_FLAG_LOGGING
, &em
->flags
))
411 list_del_init(&em
->list
);
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