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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
d1310b2e | 2 | #include <linux/err.h> |
d1310b2e | 3 | #include <linux/slab.h> |
a52d9a80 | 4 | #include <linux/spinlock.h> |
d1310b2e | 5 | #include <linux/hardirq.h> |
261507a0 | 6 | #include "ctree.h" |
a52d9a80 | 7 | #include "extent_map.h" |
ebb8765b | 8 | #include "compression.h" |
a52d9a80 | 9 | |
86479a04 | 10 | |
a52d9a80 | 11 | static struct kmem_cache *extent_map_cache; |
ca664626 | 12 | |
2f4cbe64 | 13 | int __init extent_map_init(void) |
a52d9a80 | 14 | { |
837e1972 | 15 | extent_map_cache = kmem_cache_create("btrfs_extent_map", |
9601e3f6 | 16 | sizeof(struct extent_map), 0, |
fba4b697 | 17 | SLAB_MEM_SPREAD, NULL); |
2f4cbe64 WB |
18 | if (!extent_map_cache) |
19 | return -ENOMEM; | |
2f4cbe64 | 20 | return 0; |
a52d9a80 CM |
21 | } |
22 | ||
17636e03 | 23 | void extent_map_exit(void) |
a52d9a80 | 24 | { |
5598e900 | 25 | kmem_cache_destroy(extent_map_cache); |
a52d9a80 CM |
26 | } |
27 | ||
9d2423c5 CH |
28 | /** |
29 | * extent_map_tree_init - initialize extent map tree | |
30 | * @tree: tree to initialize | |
9d2423c5 CH |
31 | * |
32 | * Initialize the extent tree @tree. Should be called for each new inode | |
33 | * or other user of the extent_map interface. | |
34 | */ | |
a8067e02 | 35 | void extent_map_tree_init(struct extent_map_tree *tree) |
a52d9a80 | 36 | { |
6bef4d31 | 37 | tree->map = RB_ROOT; |
5dc562c5 | 38 | INIT_LIST_HEAD(&tree->modified_extents); |
890871be | 39 | rwlock_init(&tree->lock); |
a52d9a80 | 40 | } |
a52d9a80 | 41 | |
9d2423c5 CH |
42 | /** |
43 | * alloc_extent_map - allocate new extent map structure | |
9d2423c5 CH |
44 | * |
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() | |
48 | */ | |
172ddd60 | 49 | struct extent_map *alloc_extent_map(void) |
a52d9a80 CM |
50 | { |
51 | struct extent_map *em; | |
70c8a91c | 52 | em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS); |
c26a9203 TI |
53 | if (!em) |
54 | return NULL; | |
cbc0e928 | 55 | RB_CLEAR_NODE(&em->rb_node); |
d1310b2e | 56 | em->flags = 0; |
261507a0 | 57 | em->compress_type = BTRFS_COMPRESS_NONE; |
5dc562c5 | 58 | em->generation = 0; |
490b54d6 | 59 | refcount_set(&em->refs, 1); |
5dc562c5 | 60 | INIT_LIST_HEAD(&em->list); |
a52d9a80 CM |
61 | return em; |
62 | } | |
a52d9a80 | 63 | |
9d2423c5 CH |
64 | /** |
65 | * free_extent_map - drop reference count of an extent_map | |
01327610 | 66 | * @em: extent map being released |
9d2423c5 CH |
67 | * |
68 | * Drops the reference out on @em by one and free the structure | |
69 | * if the reference count hits zero. | |
70 | */ | |
a52d9a80 CM |
71 | void free_extent_map(struct extent_map *em) |
72 | { | |
2bf5a725 CM |
73 | if (!em) |
74 | return; | |
490b54d6 ER |
75 | WARN_ON(refcount_read(&em->refs) == 0); |
76 | if (refcount_dec_and_test(&em->refs)) { | |
cbc0e928 | 77 | WARN_ON(extent_map_in_tree(em)); |
5dc562c5 | 78 | WARN_ON(!list_empty(&em->list)); |
298a8f9c | 79 | if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags)) |
95617d69 | 80 | kfree(em->map_lookup); |
a52d9a80 CM |
81 | kmem_cache_free(extent_map_cache, em); |
82 | } | |
83 | } | |
a52d9a80 | 84 | |
32193c14 FDBM |
85 | /* simple helper to do math around the end of an extent, handling wrap */ |
86 | static u64 range_end(u64 start, u64 len) | |
87 | { | |
88 | if (start + len < start) | |
89 | return (u64)-1; | |
90 | return start + len; | |
91 | } | |
92 | ||
93 | static int tree_insert(struct rb_root *root, struct extent_map *em) | |
a52d9a80 | 94 | { |
d397712b CM |
95 | struct rb_node **p = &root->rb_node; |
96 | struct rb_node *parent = NULL; | |
32193c14 FDBM |
97 | struct extent_map *entry = NULL; |
98 | struct rb_node *orig_parent = NULL; | |
99 | u64 end = range_end(em->start, em->len); | |
a52d9a80 | 100 | |
d397712b | 101 | while (*p) { |
a52d9a80 | 102 | parent = *p; |
d1310b2e CM |
103 | entry = rb_entry(parent, struct extent_map, rb_node); |
104 | ||
32193c14 | 105 | if (em->start < entry->start) |
a52d9a80 | 106 | p = &(*p)->rb_left; |
32193c14 | 107 | else if (em->start >= extent_map_end(entry)) |
a52d9a80 CM |
108 | p = &(*p)->rb_right; |
109 | else | |
32193c14 | 110 | return -EEXIST; |
a52d9a80 CM |
111 | } |
112 | ||
32193c14 FDBM |
113 | orig_parent = parent; |
114 | while (parent && em->start >= extent_map_end(entry)) { | |
115 | parent = rb_next(parent); | |
116 | entry = rb_entry(parent, struct extent_map, rb_node); | |
117 | } | |
118 | if (parent) | |
119 | if (end > entry->start && em->start < extent_map_end(entry)) | |
120 | return -EEXIST; | |
121 | ||
122 | parent = orig_parent; | |
123 | entry = rb_entry(parent, struct extent_map, rb_node); | |
124 | while (parent && em->start < entry->start) { | |
125 | parent = rb_prev(parent); | |
126 | entry = rb_entry(parent, struct extent_map, rb_node); | |
127 | } | |
128 | if (parent) | |
129 | if (end > entry->start && em->start < extent_map_end(entry)) | |
130 | return -EEXIST; | |
131 | ||
32193c14 FDBM |
132 | rb_link_node(&em->rb_node, orig_parent, p); |
133 | rb_insert_color(&em->rb_node, root); | |
134 | return 0; | |
a52d9a80 CM |
135 | } |
136 | ||
d352ac68 CM |
137 | /* |
138 | * search through the tree for an extent_map with a given offset. If | |
139 | * it can't be found, try to find some neighboring extents | |
140 | */ | |
a52d9a80 | 141 | static struct rb_node *__tree_search(struct rb_root *root, u64 offset, |
5f56406a CM |
142 | struct rb_node **prev_ret, |
143 | struct rb_node **next_ret) | |
a52d9a80 | 144 | { |
d397712b | 145 | struct rb_node *n = root->rb_node; |
a52d9a80 | 146 | struct rb_node *prev = NULL; |
5f56406a | 147 | struct rb_node *orig_prev = NULL; |
d1310b2e CM |
148 | struct extent_map *entry; |
149 | struct extent_map *prev_entry = NULL; | |
a52d9a80 | 150 | |
d397712b | 151 | while (n) { |
d1310b2e | 152 | entry = rb_entry(n, struct extent_map, rb_node); |
a52d9a80 CM |
153 | prev = n; |
154 | prev_entry = entry; | |
155 | ||
156 | if (offset < entry->start) | |
157 | n = n->rb_left; | |
d1310b2e | 158 | else if (offset >= extent_map_end(entry)) |
a52d9a80 CM |
159 | n = n->rb_right; |
160 | else | |
161 | return n; | |
162 | } | |
5f56406a CM |
163 | |
164 | if (prev_ret) { | |
165 | orig_prev = prev; | |
d397712b | 166 | while (prev && offset >= extent_map_end(prev_entry)) { |
5f56406a | 167 | prev = rb_next(prev); |
d1310b2e | 168 | prev_entry = rb_entry(prev, struct extent_map, rb_node); |
5f56406a CM |
169 | } |
170 | *prev_ret = prev; | |
171 | prev = orig_prev; | |
172 | } | |
173 | ||
174 | if (next_ret) { | |
d1310b2e | 175 | prev_entry = rb_entry(prev, struct extent_map, rb_node); |
d397712b | 176 | while (prev && offset < prev_entry->start) { |
5f56406a | 177 | prev = rb_prev(prev); |
d1310b2e | 178 | prev_entry = rb_entry(prev, struct extent_map, rb_node); |
5f56406a CM |
179 | } |
180 | *next_ret = prev; | |
a52d9a80 | 181 | } |
a52d9a80 CM |
182 | return NULL; |
183 | } | |
184 | ||
d352ac68 | 185 | /* check to see if two extent_map structs are adjacent and safe to merge */ |
d1310b2e | 186 | static int mergable_maps(struct extent_map *prev, struct extent_map *next) |
a52d9a80 | 187 | { |
7f3c74fb CM |
188 | if (test_bit(EXTENT_FLAG_PINNED, &prev->flags)) |
189 | return 0; | |
190 | ||
c8b97818 CM |
191 | /* |
192 | * don't merge compressed extents, we need to know their | |
193 | * actual size | |
194 | */ | |
195 | if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags)) | |
196 | return 0; | |
197 | ||
201a9038 JB |
198 | if (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) || |
199 | test_bit(EXTENT_FLAG_LOGGING, &next->flags)) | |
200 | return 0; | |
201 | ||
09a2a8f9 JB |
202 | /* |
203 | * We don't want to merge stuff that hasn't been written to the log yet | |
204 | * since it may not reflect exactly what is on disk, and that would be | |
205 | * bad. | |
206 | */ | |
207 | if (!list_empty(&prev->list) || !list_empty(&next->list)) | |
208 | return 0; | |
209 | ||
d1310b2e CM |
210 | if (extent_map_end(prev) == next->start && |
211 | prev->flags == next->flags && | |
212 | prev->bdev == next->bdev && | |
213 | ((next->block_start == EXTENT_MAP_HOLE && | |
214 | prev->block_start == EXTENT_MAP_HOLE) || | |
215 | (next->block_start == EXTENT_MAP_INLINE && | |
216 | prev->block_start == EXTENT_MAP_INLINE) || | |
217 | (next->block_start == EXTENT_MAP_DELALLOC && | |
218 | prev->block_start == EXTENT_MAP_DELALLOC) || | |
219 | (next->block_start < EXTENT_MAP_LAST_BYTE - 1 && | |
220 | next->block_start == extent_map_block_end(prev)))) { | |
221 | return 1; | |
222 | } | |
a52d9a80 CM |
223 | return 0; |
224 | } | |
225 | ||
4d2c8f62 | 226 | static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em) |
a1ed835e | 227 | { |
a1ed835e CM |
228 | struct extent_map *merge = NULL; |
229 | struct rb_node *rb; | |
a1ed835e CM |
230 | |
231 | if (em->start != 0) { | |
232 | rb = rb_prev(&em->rb_node); | |
233 | if (rb) | |
234 | merge = rb_entry(rb, struct extent_map, rb_node); | |
235 | if (rb && mergable_maps(merge, em)) { | |
236 | em->start = merge->start; | |
70c8a91c | 237 | em->orig_start = merge->orig_start; |
a1ed835e CM |
238 | em->len += merge->len; |
239 | em->block_len += merge->block_len; | |
240 | em->block_start = merge->block_start; | |
70c8a91c JB |
241 | em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start; |
242 | em->mod_start = merge->mod_start; | |
243 | em->generation = max(em->generation, merge->generation); | |
5dc562c5 | 244 | |
a1ed835e | 245 | rb_erase(&merge->rb_node, &tree->map); |
cbc0e928 | 246 | RB_CLEAR_NODE(&merge->rb_node); |
a1ed835e CM |
247 | free_extent_map(merge); |
248 | } | |
249 | } | |
250 | ||
251 | rb = rb_next(&em->rb_node); | |
252 | if (rb) | |
253 | merge = rb_entry(rb, struct extent_map, rb_node); | |
254 | if (rb && mergable_maps(em, merge)) { | |
255 | em->len += merge->len; | |
d527afe1 | 256 | em->block_len += merge->block_len; |
a1ed835e | 257 | rb_erase(&merge->rb_node, &tree->map); |
cbc0e928 | 258 | RB_CLEAR_NODE(&merge->rb_node); |
70c8a91c JB |
259 | em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start; |
260 | em->generation = max(em->generation, merge->generation); | |
a1ed835e CM |
261 | free_extent_map(merge); |
262 | } | |
4d2c8f62 LZ |
263 | } |
264 | ||
5dc562c5 | 265 | /** |
52b1de91 | 266 | * unpin_extent_cache - unpin an extent from the cache |
5dc562c5 JB |
267 | * @tree: tree to unpin the extent in |
268 | * @start: logical offset in the file | |
269 | * @len: length of the extent | |
270 | * @gen: generation that this extent has been modified in | |
5dc562c5 JB |
271 | * |
272 | * Called after an extent has been written to disk properly. Set the generation | |
273 | * to the generation that actually added the file item to the inode so we know | |
274 | * we need to sync this extent when we call fsync(). | |
275 | */ | |
276 | int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len, | |
277 | u64 gen) | |
4d2c8f62 LZ |
278 | { |
279 | int ret = 0; | |
280 | struct extent_map *em; | |
4e2f84e6 | 281 | bool prealloc = false; |
4d2c8f62 LZ |
282 | |
283 | write_lock(&tree->lock); | |
284 | em = lookup_extent_mapping(tree, start, len); | |
285 | ||
286 | WARN_ON(!em || em->start != start); | |
287 | ||
288 | if (!em) | |
289 | goto out; | |
290 | ||
5dc562c5 | 291 | em->generation = gen; |
4d2c8f62 | 292 | clear_bit(EXTENT_FLAG_PINNED, &em->flags); |
4e2f84e6 LB |
293 | em->mod_start = em->start; |
294 | em->mod_len = em->len; | |
295 | ||
b11e234d | 296 | if (test_bit(EXTENT_FLAG_FILLING, &em->flags)) { |
4e2f84e6 | 297 | prealloc = true; |
b11e234d | 298 | clear_bit(EXTENT_FLAG_FILLING, &em->flags); |
4e2f84e6 | 299 | } |
4d2c8f62 LZ |
300 | |
301 | try_merge_map(tree, em); | |
4e2f84e6 LB |
302 | |
303 | if (prealloc) { | |
304 | em->mod_start = em->start; | |
305 | em->mod_len = em->len; | |
306 | } | |
307 | ||
a1ed835e CM |
308 | free_extent_map(em); |
309 | out: | |
310 | write_unlock(&tree->lock); | |
311 | return ret; | |
312 | ||
313 | } | |
314 | ||
201a9038 JB |
315 | void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em) |
316 | { | |
317 | clear_bit(EXTENT_FLAG_LOGGING, &em->flags); | |
cbc0e928 | 318 | if (extent_map_in_tree(em)) |
222c81dc | 319 | try_merge_map(tree, em); |
201a9038 JB |
320 | } |
321 | ||
176840b3 FM |
322 | static inline void setup_extent_mapping(struct extent_map_tree *tree, |
323 | struct extent_map *em, | |
324 | int modified) | |
325 | { | |
490b54d6 | 326 | refcount_inc(&em->refs); |
176840b3 FM |
327 | em->mod_start = em->start; |
328 | em->mod_len = em->len; | |
329 | ||
330 | if (modified) | |
331 | list_move(&em->list, &tree->modified_extents); | |
332 | else | |
333 | try_merge_map(tree, em); | |
334 | } | |
335 | ||
9d2423c5 CH |
336 | /** |
337 | * add_extent_mapping - add new extent map to the extent tree | |
338 | * @tree: tree to insert new map in | |
339 | * @em: map to insert | |
340 | * | |
341 | * Insert @em into @tree or perform a simple forward/backward merge with | |
342 | * existing mappings. The extent_map struct passed in will be inserted | |
343 | * into the tree directly, with an additional reference taken, or a | |
25985edc | 344 | * reference dropped if the merge attempt was successful. |
a52d9a80 CM |
345 | */ |
346 | int add_extent_mapping(struct extent_map_tree *tree, | |
09a2a8f9 | 347 | struct extent_map *em, int modified) |
a52d9a80 CM |
348 | { |
349 | int ret = 0; | |
a52d9a80 | 350 | |
32193c14 FDBM |
351 | ret = tree_insert(&tree->map, em); |
352 | if (ret) | |
a52d9a80 | 353 | goto out; |
32193c14 | 354 | |
176840b3 | 355 | setup_extent_mapping(tree, em, modified); |
a52d9a80 | 356 | out: |
a52d9a80 CM |
357 | return ret; |
358 | } | |
a52d9a80 | 359 | |
48a3b636 ES |
360 | static struct extent_map * |
361 | __lookup_extent_mapping(struct extent_map_tree *tree, | |
362 | u64 start, u64 len, int strict) | |
a52d9a80 CM |
363 | { |
364 | struct extent_map *em; | |
365 | struct rb_node *rb_node; | |
306929f3 CH |
366 | struct rb_node *prev = NULL; |
367 | struct rb_node *next = NULL; | |
368 | u64 end = range_end(start, len); | |
369 | ||
5f56406a | 370 | rb_node = __tree_search(&tree->map, start, &prev, &next); |
a52d9a80 | 371 | if (!rb_node) { |
ed64f066 LZ |
372 | if (prev) |
373 | rb_node = prev; | |
374 | else if (next) | |
375 | rb_node = next; | |
376 | else | |
377 | return NULL; | |
a52d9a80 | 378 | } |
ed64f066 | 379 | |
a52d9a80 | 380 | em = rb_entry(rb_node, struct extent_map, rb_node); |
d1310b2e | 381 | |
ed64f066 LZ |
382 | if (strict && !(end > em->start && start < extent_map_end(em))) |
383 | return NULL; | |
d1310b2e | 384 | |
490b54d6 | 385 | refcount_inc(&em->refs); |
a52d9a80 CM |
386 | return em; |
387 | } | |
a52d9a80 | 388 | |
ed64f066 LZ |
389 | /** |
390 | * lookup_extent_mapping - lookup extent_map | |
391 | * @tree: tree to lookup in | |
392 | * @start: byte offset to start the search | |
393 | * @len: length of the lookup range | |
394 | * | |
395 | * Find and return the first extent_map struct in @tree that intersects the | |
396 | * [start, len] range. There may be additional objects in the tree that | |
397 | * intersect, so check the object returned carefully to make sure that no | |
398 | * additional lookups are needed. | |
399 | */ | |
400 | struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree, | |
401 | u64 start, u64 len) | |
402 | { | |
403 | return __lookup_extent_mapping(tree, start, len, 1); | |
404 | } | |
405 | ||
b917b7c3 CM |
406 | /** |
407 | * search_extent_mapping - find a nearby extent map | |
408 | * @tree: tree to lookup in | |
409 | * @start: byte offset to start the search | |
410 | * @len: length of the lookup range | |
411 | * | |
412 | * Find and return the first extent_map struct in @tree that intersects the | |
413 | * [start, len] range. | |
414 | * | |
415 | * If one can't be found, any nearby extent may be returned | |
416 | */ | |
417 | struct extent_map *search_extent_mapping(struct extent_map_tree *tree, | |
418 | u64 start, u64 len) | |
419 | { | |
ed64f066 | 420 | return __lookup_extent_mapping(tree, start, len, 0); |
b917b7c3 CM |
421 | } |
422 | ||
9d2423c5 CH |
423 | /** |
424 | * remove_extent_mapping - removes an extent_map from the extent tree | |
425 | * @tree: extent tree to remove from | |
bb7ab3b9 | 426 | * @em: extent map being removed |
9d2423c5 CH |
427 | * |
428 | * Removes @em from @tree. No reference counts are dropped, and no checks | |
429 | * are done to see if the range is in use | |
a52d9a80 CM |
430 | */ |
431 | int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em) | |
432 | { | |
d1310b2e | 433 | int ret = 0; |
a52d9a80 | 434 | |
7f3c74fb | 435 | WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags)); |
d1310b2e | 436 | rb_erase(&em->rb_node, &tree->map); |
ff44c6e3 JB |
437 | if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags)) |
438 | list_del_init(&em->list); | |
cbc0e928 | 439 | RB_CLEAR_NODE(&em->rb_node); |
a52d9a80 CM |
440 | return ret; |
441 | } | |
176840b3 FM |
442 | |
443 | void replace_extent_mapping(struct extent_map_tree *tree, | |
444 | struct extent_map *cur, | |
445 | struct extent_map *new, | |
446 | int modified) | |
447 | { | |
448 | WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags)); | |
449 | ASSERT(extent_map_in_tree(cur)); | |
450 | if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags)) | |
451 | list_del_init(&cur->list); | |
452 | rb_replace_node(&cur->rb_node, &new->rb_node, &tree->map); | |
453 | RB_CLEAR_NODE(&cur->rb_node); | |
454 | ||
455 | setup_extent_mapping(tree, new, modified); | |
456 | } | |
c04e61b5 LB |
457 | |
458 | static struct extent_map *next_extent_map(struct extent_map *em) | |
459 | { | |
460 | struct rb_node *next; | |
461 | ||
462 | next = rb_next(&em->rb_node); | |
463 | if (!next) | |
464 | return NULL; | |
465 | return container_of(next, struct extent_map, rb_node); | |
466 | } | |
467 | ||
468 | static struct extent_map *prev_extent_map(struct extent_map *em) | |
469 | { | |
470 | struct rb_node *prev; | |
471 | ||
472 | prev = rb_prev(&em->rb_node); | |
473 | if (!prev) | |
474 | return NULL; | |
475 | return container_of(prev, struct extent_map, rb_node); | |
476 | } | |
477 | ||
478 | /* helper for btfs_get_extent. Given an existing extent in the tree, | |
479 | * the existing extent is the nearest extent to map_start, | |
480 | * and an extent that you want to insert, deal with overlap and insert | |
481 | * the best fitted new extent into the tree. | |
482 | */ | |
5f4791f4 LB |
483 | static noinline int merge_extent_mapping(struct extent_map_tree *em_tree, |
484 | struct extent_map *existing, | |
485 | struct extent_map *em, | |
486 | u64 map_start) | |
c04e61b5 LB |
487 | { |
488 | struct extent_map *prev; | |
489 | struct extent_map *next; | |
490 | u64 start; | |
491 | u64 end; | |
492 | u64 start_diff; | |
493 | ||
494 | BUG_ON(map_start < em->start || map_start >= extent_map_end(em)); | |
495 | ||
496 | if (existing->start > map_start) { | |
497 | next = existing; | |
498 | prev = prev_extent_map(next); | |
499 | } else { | |
500 | prev = existing; | |
501 | next = next_extent_map(prev); | |
502 | } | |
503 | ||
504 | start = prev ? extent_map_end(prev) : em->start; | |
505 | start = max_t(u64, start, em->start); | |
506 | end = next ? next->start : extent_map_end(em); | |
507 | end = min_t(u64, end, extent_map_end(em)); | |
508 | start_diff = start - em->start; | |
509 | em->start = start; | |
510 | em->len = end - start; | |
511 | if (em->block_start < EXTENT_MAP_LAST_BYTE && | |
512 | !test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) { | |
513 | em->block_start += start_diff; | |
514 | em->block_len = em->len; | |
515 | } | |
516 | return add_extent_mapping(em_tree, em, 0); | |
517 | } | |
518 | ||
519 | /** | |
520 | * btrfs_add_extent_mapping - add extent mapping into em_tree | |
521 | * @em_tree - the extent tree into which we want to insert the extent mapping | |
522 | * @em_in - extent we are inserting | |
523 | * @start - start of the logical range btrfs_get_extent() is requesting | |
524 | * @len - length of the logical range btrfs_get_extent() is requesting | |
525 | * | |
526 | * Note that @em_in's range may be different from [start, start+len), | |
527 | * but they must be overlapped. | |
528 | * | |
529 | * Insert @em_in into @em_tree. In case there is an overlapping range, handle | |
530 | * the -EEXIST by either: | |
531 | * a) Returning the existing extent in @em_in if @start is within the | |
532 | * existing em. | |
533 | * b) Merge the existing extent with @em_in passed in. | |
534 | * | |
535 | * Return 0 on success, otherwise -EEXIST. | |
536 | * | |
537 | */ | |
538 | int btrfs_add_extent_mapping(struct extent_map_tree *em_tree, | |
539 | struct extent_map **em_in, u64 start, u64 len) | |
540 | { | |
541 | int ret; | |
542 | struct extent_map *em = *em_in; | |
543 | ||
544 | ret = add_extent_mapping(em_tree, em, 0); | |
545 | /* it is possible that someone inserted the extent into the tree | |
546 | * while we had the lock dropped. It is also possible that | |
547 | * an overlapping map exists in the tree | |
548 | */ | |
549 | if (ret == -EEXIST) { | |
550 | struct extent_map *existing; | |
551 | ||
552 | ret = 0; | |
553 | ||
554 | existing = search_extent_mapping(em_tree, start, len); | |
555 | /* | |
556 | * existing will always be non-NULL, since there must be | |
557 | * extent causing the -EEXIST. | |
558 | */ | |
559 | if (start >= existing->start && | |
560 | start < extent_map_end(existing)) { | |
561 | free_extent_map(em); | |
562 | *em_in = existing; | |
563 | ret = 0; | |
564 | } else { | |
9a7e10e7 LB |
565 | u64 orig_start = em->start; |
566 | u64 orig_len = em->len; | |
567 | ||
c04e61b5 LB |
568 | /* |
569 | * The existing extent map is the one nearest to | |
570 | * the [start, start + len) range which overlaps | |
571 | */ | |
572 | ret = merge_extent_mapping(em_tree, existing, | |
573 | em, start); | |
c04e61b5 LB |
574 | if (ret) { |
575 | free_extent_map(em); | |
576 | *em_in = NULL; | |
9a7e10e7 LB |
577 | WARN_ONCE(ret, |
578 | "unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n", | |
579 | ret, existing->start, existing->len, | |
580 | orig_start, orig_len); | |
c04e61b5 | 581 | } |
9a7e10e7 | 582 | free_extent_map(existing); |
c04e61b5 LB |
583 | } |
584 | } | |
585 | ||
586 | ASSERT(ret == 0 || ret == -EEXIST); | |
587 | return ret; | |
588 | } |