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1#include <linux/err.h>
2#include <linux/slab.h>
3#include <linux/module.h>
4#include <linux/spinlock.h>
5#include <linux/hardirq.h>
6#include "ctree.h"
7#include "extent_map.h"
8
9
10static struct kmem_cache *extent_map_cache;
11
12int __init extent_map_init(void)
13{
14 extent_map_cache = kmem_cache_create("extent_map",
15 sizeof(struct extent_map), 0,
16 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
17 if (!extent_map_cache)
18 return -ENOMEM;
19 return 0;
20}
21
22void extent_map_exit(void)
23{
24 if (extent_map_cache)
25 kmem_cache_destroy(extent_map_cache);
26}
27
28/**
29 * extent_map_tree_init - initialize extent map tree
30 * @tree: tree to initialize
31 *
32 * Initialize the extent tree @tree. Should be called for each new inode
33 * or other user of the extent_map interface.
34 */
35void extent_map_tree_init(struct extent_map_tree *tree)
36{
37 tree->map = RB_ROOT;
38 rwlock_init(&tree->lock);
39}
40
41/**
42 * alloc_extent_map - allocate new extent map structure
43 *
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()
47 */
48struct extent_map *alloc_extent_map(void)
49{
50 struct extent_map *em;
51 em = kmem_cache_alloc(extent_map_cache, GFP_NOFS);
52 if (!em)
53 return NULL;
54 em->in_tree = 0;
55 em->flags = 0;
56 em->compress_type = BTRFS_COMPRESS_NONE;
57 atomic_set(&em->refs, 1);
58 return em;
59}
60
61/**
62 * free_extent_map - drop reference count of an extent_map
63 * @em: extent map beeing releasead
64 *
65 * Drops the reference out on @em by one and free the structure
66 * if the reference count hits zero.
67 */
68void free_extent_map(struct extent_map *em)
69{
70 if (!em)
71 return;
72 WARN_ON(atomic_read(&em->refs) == 0);
73 if (atomic_dec_and_test(&em->refs)) {
74 WARN_ON(em->in_tree);
75 kmem_cache_free(extent_map_cache, em);
76 }
77}
78
79static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
80 struct rb_node *node)
81{
82 struct rb_node **p = &root->rb_node;
83 struct rb_node *parent = NULL;
84 struct extent_map *entry;
85
86 while (*p) {
87 parent = *p;
88 entry = rb_entry(parent, struct extent_map, rb_node);
89
90 WARN_ON(!entry->in_tree);
91
92 if (offset < entry->start)
93 p = &(*p)->rb_left;
94 else if (offset >= extent_map_end(entry))
95 p = &(*p)->rb_right;
96 else
97 return parent;
98 }
99
100 entry = rb_entry(node, struct extent_map, rb_node);
101 entry->in_tree = 1;
102 rb_link_node(node, parent, p);
103 rb_insert_color(node, root);
104 return NULL;
105}
106
107/*
108 * search through the tree for an extent_map with a given offset. If
109 * it can't be found, try to find some neighboring extents
110 */
111static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
112 struct rb_node **prev_ret,
113 struct rb_node **next_ret)
114{
115 struct rb_node *n = root->rb_node;
116 struct rb_node *prev = NULL;
117 struct rb_node *orig_prev = NULL;
118 struct extent_map *entry;
119 struct extent_map *prev_entry = NULL;
120
121 while (n) {
122 entry = rb_entry(n, struct extent_map, rb_node);
123 prev = n;
124 prev_entry = entry;
125
126 WARN_ON(!entry->in_tree);
127
128 if (offset < entry->start)
129 n = n->rb_left;
130 else if (offset >= extent_map_end(entry))
131 n = n->rb_right;
132 else
133 return n;
134 }
135
136 if (prev_ret) {
137 orig_prev = prev;
138 while (prev && offset >= extent_map_end(prev_entry)) {
139 prev = rb_next(prev);
140 prev_entry = rb_entry(prev, struct extent_map, rb_node);
141 }
142 *prev_ret = prev;
143 prev = orig_prev;
144 }
145
146 if (next_ret) {
147 prev_entry = rb_entry(prev, struct extent_map, rb_node);
148 while (prev && offset < prev_entry->start) {
149 prev = rb_prev(prev);
150 prev_entry = rb_entry(prev, struct extent_map, rb_node);
151 }
152 *next_ret = prev;
153 }
154 return NULL;
155}
156
157/* check to see if two extent_map structs are adjacent and safe to merge */
158static int mergable_maps(struct extent_map *prev, struct extent_map *next)
159{
160 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
161 return 0;
162
163 /*
164 * don't merge compressed extents, we need to know their
165 * actual size
166 */
167 if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
168 return 0;
169
170 if (extent_map_end(prev) == next->start &&
171 prev->flags == next->flags &&
172 prev->bdev == next->bdev &&
173 ((next->block_start == EXTENT_MAP_HOLE &&
174 prev->block_start == EXTENT_MAP_HOLE) ||
175 (next->block_start == EXTENT_MAP_INLINE &&
176 prev->block_start == EXTENT_MAP_INLINE) ||
177 (next->block_start == EXTENT_MAP_DELALLOC &&
178 prev->block_start == EXTENT_MAP_DELALLOC) ||
179 (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
180 next->block_start == extent_map_block_end(prev)))) {
181 return 1;
182 }
183 return 0;
184}
185
186static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
187{
188 struct extent_map *merge = NULL;
189 struct rb_node *rb;
190
191 if (em->start != 0) {
192 rb = rb_prev(&em->rb_node);
193 if (rb)
194 merge = rb_entry(rb, struct extent_map, rb_node);
195 if (rb && mergable_maps(merge, em)) {
196 em->start = merge->start;
197 em->len += merge->len;
198 em->block_len += merge->block_len;
199 em->block_start = merge->block_start;
200 merge->in_tree = 0;
201 rb_erase(&merge->rb_node, &tree->map);
202 free_extent_map(merge);
203 }
204 }
205
206 rb = rb_next(&em->rb_node);
207 if (rb)
208 merge = rb_entry(rb, struct extent_map, rb_node);
209 if (rb && mergable_maps(em, merge)) {
210 em->len += merge->len;
211 em->block_len += merge->len;
212 rb_erase(&merge->rb_node, &tree->map);
213 merge->in_tree = 0;
214 free_extent_map(merge);
215 }
216}
217
218int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
219{
220 int ret = 0;
221 struct extent_map *em;
222
223 write_lock(&tree->lock);
224 em = lookup_extent_mapping(tree, start, len);
225
226 WARN_ON(!em || em->start != start);
227
228 if (!em)
229 goto out;
230
231 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
232
233 try_merge_map(tree, em);
234
235 free_extent_map(em);
236out:
237 write_unlock(&tree->lock);
238 return ret;
239
240}
241
242/**
243 * add_extent_mapping - add new extent map to the extent tree
244 * @tree: tree to insert new map in
245 * @em: map to insert
246 *
247 * Insert @em into @tree or perform a simple forward/backward merge with
248 * existing mappings. The extent_map struct passed in will be inserted
249 * into the tree directly, with an additional reference taken, or a
250 * reference dropped if the merge attempt was successful.
251 */
252int add_extent_mapping(struct extent_map_tree *tree,
253 struct extent_map *em)
254{
255 int ret = 0;
256 struct rb_node *rb;
257 struct extent_map *exist;
258
259 exist = lookup_extent_mapping(tree, em->start, em->len);
260 if (exist) {
261 free_extent_map(exist);
262 ret = -EEXIST;
263 goto out;
264 }
265 rb = tree_insert(&tree->map, em->start, &em->rb_node);
266 if (rb) {
267 ret = -EEXIST;
268 goto out;
269 }
270 atomic_inc(&em->refs);
271
272 try_merge_map(tree, em);
273out:
274 return ret;
275}
276
277/* simple helper to do math around the end of an extent, handling wrap */
278static u64 range_end(u64 start, u64 len)
279{
280 if (start + len < start)
281 return (u64)-1;
282 return start + len;
283}
284
285struct extent_map *__lookup_extent_mapping(struct extent_map_tree *tree,
286 u64 start, u64 len, int strict)
287{
288 struct extent_map *em;
289 struct rb_node *rb_node;
290 struct rb_node *prev = NULL;
291 struct rb_node *next = NULL;
292 u64 end = range_end(start, len);
293
294 rb_node = __tree_search(&tree->map, start, &prev, &next);
295 if (!rb_node) {
296 if (prev)
297 rb_node = prev;
298 else if (next)
299 rb_node = next;
300 else
301 return NULL;
302 }
303
304 em = rb_entry(rb_node, struct extent_map, rb_node);
305
306 if (strict && !(end > em->start && start < extent_map_end(em)))
307 return NULL;
308
309 atomic_inc(&em->refs);
310 return em;
311}
312
313/**
314 * lookup_extent_mapping - lookup extent_map
315 * @tree: tree to lookup in
316 * @start: byte offset to start the search
317 * @len: length of the lookup range
318 *
319 * Find and return the first extent_map struct in @tree that intersects the
320 * [start, len] range. There may be additional objects in the tree that
321 * intersect, so check the object returned carefully to make sure that no
322 * additional lookups are needed.
323 */
324struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
325 u64 start, u64 len)
326{
327 return __lookup_extent_mapping(tree, start, len, 1);
328}
329
330/**
331 * search_extent_mapping - find a nearby extent map
332 * @tree: tree to lookup in
333 * @start: byte offset to start the search
334 * @len: length of the lookup range
335 *
336 * Find and return the first extent_map struct in @tree that intersects the
337 * [start, len] range.
338 *
339 * If one can't be found, any nearby extent may be returned
340 */
341struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
342 u64 start, u64 len)
343{
344 return __lookup_extent_mapping(tree, start, len, 0);
345}
346
347/**
348 * remove_extent_mapping - removes an extent_map from the extent tree
349 * @tree: extent tree to remove from
350 * @em: extent map beeing removed
351 *
352 * Removes @em from @tree. No reference counts are dropped, and no checks
353 * are done to see if the range is in use
354 */
355int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
356{
357 int ret = 0;
358
359 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
360 rb_erase(&em->rb_node, &tree->map);
361 em->in_tree = 0;
362 return ret;
363}
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 "ctree.h"
7#include "extent_map.h"
8#include "compression.h"
9
10
11static struct kmem_cache *extent_map_cache;
12
13int __init extent_map_init(void)
14{
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)
19 return -ENOMEM;
20 return 0;
21}
22
23void __cold extent_map_exit(void)
24{
25 kmem_cache_destroy(extent_map_cache);
26}
27
28/**
29 * extent_map_tree_init - initialize extent map tree
30 * @tree: tree to initialize
31 *
32 * Initialize the extent tree @tree. Should be called for each new inode
33 * or other user of the extent_map interface.
34 */
35void extent_map_tree_init(struct extent_map_tree *tree)
36{
37 tree->map = RB_ROOT;
38 INIT_LIST_HEAD(&tree->modified_extents);
39 rwlock_init(&tree->lock);
40}
41
42/**
43 * alloc_extent_map - allocate new extent map structure
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 */
49struct extent_map *alloc_extent_map(void)
50{
51 struct extent_map *em;
52 em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
53 if (!em)
54 return NULL;
55 RB_CLEAR_NODE(&em->rb_node);
56 em->flags = 0;
57 em->compress_type = BTRFS_COMPRESS_NONE;
58 em->generation = 0;
59 refcount_set(&em->refs, 1);
60 INIT_LIST_HEAD(&em->list);
61 return em;
62}
63
64/**
65 * free_extent_map - drop reference count of an extent_map
66 * @em: extent map being released
67 *
68 * Drops the reference out on @em by one and free the structure
69 * if the reference count hits zero.
70 */
71void free_extent_map(struct extent_map *em)
72{
73 if (!em)
74 return;
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);
82 }
83}
84
85/* simple helper to do math around the end of an extent, handling wrap */
86static u64 range_end(u64 start, u64 len)
87{
88 if (start + len < start)
89 return (u64)-1;
90 return start + len;
91}
92
93static int tree_insert(struct rb_root *root, struct extent_map *em)
94{
95 struct rb_node **p = &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
101 while (*p) {
102 parent = *p;
103 entry = rb_entry(parent, struct extent_map, rb_node);
104
105 if (em->start < entry->start)
106 p = &(*p)->rb_left;
107 else if (em->start >= extent_map_end(entry))
108 p = &(*p)->rb_right;
109 else
110 return -EEXIST;
111 }
112
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
132 rb_link_node(&em->rb_node, orig_parent, p);
133 rb_insert_color(&em->rb_node, root);
134 return 0;
135}
136
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 */
141static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
142 struct rb_node **prev_ret,
143 struct rb_node **next_ret)
144{
145 struct rb_node *n = root->rb_node;
146 struct rb_node *prev = NULL;
147 struct rb_node *orig_prev = NULL;
148 struct extent_map *entry;
149 struct extent_map *prev_entry = NULL;
150
151 while (n) {
152 entry = rb_entry(n, struct extent_map, rb_node);
153 prev = n;
154 prev_entry = entry;
155
156 if (offset < entry->start)
157 n = n->rb_left;
158 else if (offset >= extent_map_end(entry))
159 n = n->rb_right;
160 else
161 return n;
162 }
163
164 if (prev_ret) {
165 orig_prev = prev;
166 while (prev && offset >= extent_map_end(prev_entry)) {
167 prev = rb_next(prev);
168 prev_entry = rb_entry(prev, struct extent_map, rb_node);
169 }
170 *prev_ret = prev;
171 prev = orig_prev;
172 }
173
174 if (next_ret) {
175 prev_entry = rb_entry(prev, struct extent_map, rb_node);
176 while (prev && offset < prev_entry->start) {
177 prev = rb_prev(prev);
178 prev_entry = rb_entry(prev, struct extent_map, rb_node);
179 }
180 *next_ret = prev;
181 }
182 return NULL;
183}
184
185/* check to see if two extent_map structs are adjacent and safe to merge */
186static int mergable_maps(struct extent_map *prev, struct extent_map *next)
187{
188 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
189 return 0;
190
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
198 if (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) ||
199 test_bit(EXTENT_FLAG_LOGGING, &next->flags))
200 return 0;
201
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
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 }
223 return 0;
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 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;
237 em->orig_start = merge->orig_start;
238 em->len += merge->len;
239 em->block_len += merge->block_len;
240 em->block_start = merge->block_start;
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);
244
245 rb_erase(&merge->rb_node, &tree->map);
246 RB_CLEAR_NODE(&merge->rb_node);
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;
256 em->block_len += merge->block_len;
257 rb_erase(&merge->rb_node, &tree->map);
258 RB_CLEAR_NODE(&merge->rb_node);
259 em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
260 em->generation = max(em->generation, merge->generation);
261 free_extent_map(merge);
262 }
263}
264
265/**
266 * unpin_extent_cache - unpin an extent from the cache
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
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 */
276int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
277 u64 gen)
278{
279 int ret = 0;
280 struct extent_map *em;
281 bool prealloc = false;
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
291 em->generation = gen;
292 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
293 em->mod_start = em->start;
294 em->mod_len = em->len;
295
296 if (test_bit(EXTENT_FLAG_FILLING, &em->flags)) {
297 prealloc = true;
298 clear_bit(EXTENT_FLAG_FILLING, &em->flags);
299 }
300
301 try_merge_map(tree, em);
302
303 if (prealloc) {
304 em->mod_start = em->start;
305 em->mod_len = em->len;
306 }
307
308 free_extent_map(em);
309out:
310 write_unlock(&tree->lock);
311 return ret;
312
313}
314
315void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
316{
317 clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
318 if (extent_map_in_tree(em))
319 try_merge_map(tree, em);
320}
321
322static inline void setup_extent_mapping(struct extent_map_tree *tree,
323 struct extent_map *em,
324 int modified)
325{
326 refcount_inc(&em->refs);
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
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
344 * reference dropped if the merge attempt was successful.
345 */
346int add_extent_mapping(struct extent_map_tree *tree,
347 struct extent_map *em, int modified)
348{
349 int ret = 0;
350
351 ret = tree_insert(&tree->map, em);
352 if (ret)
353 goto out;
354
355 setup_extent_mapping(tree, em, modified);
356out:
357 return ret;
358}
359
360static struct extent_map *
361__lookup_extent_mapping(struct extent_map_tree *tree,
362 u64 start, u64 len, int strict)
363{
364 struct extent_map *em;
365 struct rb_node *rb_node;
366 struct rb_node *prev = NULL;
367 struct rb_node *next = NULL;
368 u64 end = range_end(start, len);
369
370 rb_node = __tree_search(&tree->map, start, &prev, &next);
371 if (!rb_node) {
372 if (prev)
373 rb_node = prev;
374 else if (next)
375 rb_node = next;
376 else
377 return NULL;
378 }
379
380 em = rb_entry(rb_node, struct extent_map, rb_node);
381
382 if (strict && !(end > em->start && start < extent_map_end(em)))
383 return NULL;
384
385 refcount_inc(&em->refs);
386 return em;
387}
388
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 */
400struct 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
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 */
417struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
418 u64 start, u64 len)
419{
420 return __lookup_extent_mapping(tree, start, len, 0);
421}
422
423/**
424 * remove_extent_mapping - removes an extent_map from the extent tree
425 * @tree: extent tree to remove from
426 * @em: extent map being removed
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
430 */
431int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
432{
433 int ret = 0;
434
435 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
436 rb_erase(&em->rb_node, &tree->map);
437 if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
438 list_del_init(&em->list);
439 RB_CLEAR_NODE(&em->rb_node);
440 return ret;
441}
442
443void 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}
457
458static 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
468static 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 */
483static 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)
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 */
538int 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 trace_btrfs_handle_em_exist(existing, em, start, len);
557
558 /*
559 * existing will always be non-NULL, since there must be
560 * extent causing the -EEXIST.
561 */
562 if (start >= existing->start &&
563 start < extent_map_end(existing)) {
564 free_extent_map(em);
565 *em_in = existing;
566 ret = 0;
567 } else {
568 u64 orig_start = em->start;
569 u64 orig_len = em->len;
570
571 /*
572 * The existing extent map is the one nearest to
573 * the [start, start + len) range which overlaps
574 */
575 ret = merge_extent_mapping(em_tree, existing,
576 em, start);
577 if (ret) {
578 free_extent_map(em);
579 *em_in = NULL;
580 WARN_ONCE(ret,
581"unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
582 ret, existing->start, existing->len,
583 orig_start, orig_len);
584 }
585 free_extent_map(existing);
586 }
587 }
588
589 ASSERT(ret == 0 || ret == -EEXIST);
590 return ret;
591}