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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 "messages.h"
7#include "ctree.h"
8#include "volumes.h"
9#include "extent_map.h"
10#include "compression.h"
11#include "btrfs_inode.h"
12
13
14static struct kmem_cache *extent_map_cache;
15
16int __init extent_map_init(void)
17{
18 extent_map_cache = kmem_cache_create("btrfs_extent_map",
19 sizeof(struct extent_map), 0,
20 SLAB_MEM_SPREAD, NULL);
21 if (!extent_map_cache)
22 return -ENOMEM;
23 return 0;
24}
25
26void __cold extent_map_exit(void)
27{
28 kmem_cache_destroy(extent_map_cache);
29}
30
31/*
32 * Initialize the extent tree @tree. Should be called for each new inode or
33 * other user of the extent_map interface.
34 */
35void extent_map_tree_init(struct extent_map_tree *tree)
36{
37 tree->map = RB_ROOT_CACHED;
38 INIT_LIST_HEAD(&tree->modified_extents);
39 rwlock_init(&tree->lock);
40}
41
42/*
43 * Allocate a new extent_map structure. The new structure is returned with a
44 * reference count of one and needs to be freed using free_extent_map()
45 */
46struct extent_map *alloc_extent_map(void)
47{
48 struct extent_map *em;
49 em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
50 if (!em)
51 return NULL;
52 RB_CLEAR_NODE(&em->rb_node);
53 refcount_set(&em->refs, 1);
54 INIT_LIST_HEAD(&em->list);
55 return em;
56}
57
58/*
59 * Drop the reference out on @em by one and free the structure if the reference
60 * count hits zero.
61 */
62void free_extent_map(struct extent_map *em)
63{
64 if (!em)
65 return;
66 if (refcount_dec_and_test(&em->refs)) {
67 WARN_ON(extent_map_in_tree(em));
68 WARN_ON(!list_empty(&em->list));
69 kmem_cache_free(extent_map_cache, em);
70 }
71}
72
73/* Do the math around the end of an extent, handling wrapping. */
74static u64 range_end(u64 start, u64 len)
75{
76 if (start + len < start)
77 return (u64)-1;
78 return start + len;
79}
80
81static int tree_insert(struct rb_root_cached *root, struct extent_map *em)
82{
83 struct rb_node **p = &root->rb_root.rb_node;
84 struct rb_node *parent = NULL;
85 struct extent_map *entry = NULL;
86 struct rb_node *orig_parent = NULL;
87 u64 end = range_end(em->start, em->len);
88 bool leftmost = true;
89
90 while (*p) {
91 parent = *p;
92 entry = rb_entry(parent, struct extent_map, rb_node);
93
94 if (em->start < entry->start) {
95 p = &(*p)->rb_left;
96 } else if (em->start >= extent_map_end(entry)) {
97 p = &(*p)->rb_right;
98 leftmost = false;
99 } else {
100 return -EEXIST;
101 }
102 }
103
104 orig_parent = parent;
105 while (parent && em->start >= extent_map_end(entry)) {
106 parent = rb_next(parent);
107 entry = rb_entry(parent, struct extent_map, rb_node);
108 }
109 if (parent)
110 if (end > entry->start && em->start < extent_map_end(entry))
111 return -EEXIST;
112
113 parent = orig_parent;
114 entry = rb_entry(parent, struct extent_map, rb_node);
115 while (parent && em->start < entry->start) {
116 parent = rb_prev(parent);
117 entry = rb_entry(parent, struct extent_map, rb_node);
118 }
119 if (parent)
120 if (end > entry->start && em->start < extent_map_end(entry))
121 return -EEXIST;
122
123 rb_link_node(&em->rb_node, orig_parent, p);
124 rb_insert_color_cached(&em->rb_node, root, leftmost);
125 return 0;
126}
127
128/*
129 * Search through the tree for an extent_map with a given offset. If it can't
130 * be found, try to find some neighboring extents
131 */
132static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
133 struct rb_node **prev_or_next_ret)
134{
135 struct rb_node *n = root->rb_node;
136 struct rb_node *prev = NULL;
137 struct rb_node *orig_prev = NULL;
138 struct extent_map *entry;
139 struct extent_map *prev_entry = NULL;
140
141 ASSERT(prev_or_next_ret);
142
143 while (n) {
144 entry = rb_entry(n, struct extent_map, rb_node);
145 prev = n;
146 prev_entry = entry;
147
148 if (offset < entry->start)
149 n = n->rb_left;
150 else if (offset >= extent_map_end(entry))
151 n = n->rb_right;
152 else
153 return n;
154 }
155
156 orig_prev = prev;
157 while (prev && offset >= extent_map_end(prev_entry)) {
158 prev = rb_next(prev);
159 prev_entry = rb_entry(prev, struct extent_map, rb_node);
160 }
161
162 /*
163 * Previous extent map found, return as in this case the caller does not
164 * care about the next one.
165 */
166 if (prev) {
167 *prev_or_next_ret = prev;
168 return NULL;
169 }
170
171 prev = orig_prev;
172 prev_entry = rb_entry(prev, struct extent_map, rb_node);
173 while (prev && offset < prev_entry->start) {
174 prev = rb_prev(prev);
175 prev_entry = rb_entry(prev, struct extent_map, rb_node);
176 }
177 *prev_or_next_ret = prev;
178
179 return NULL;
180}
181
182static inline u64 extent_map_block_end(const struct extent_map *em)
183{
184 if (em->block_start + em->block_len < em->block_start)
185 return (u64)-1;
186 return em->block_start + em->block_len;
187}
188
189static bool can_merge_extent_map(const struct extent_map *em)
190{
191 if (em->flags & EXTENT_FLAG_PINNED)
192 return false;
193
194 /* Don't merge compressed extents, we need to know their actual size. */
195 if (extent_map_is_compressed(em))
196 return false;
197
198 if (em->flags & EXTENT_FLAG_LOGGING)
199 return false;
200
201 /*
202 * We don't want to merge stuff that hasn't been written to the log yet
203 * since it may not reflect exactly what is on disk, and that would be
204 * bad.
205 */
206 if (!list_empty(&em->list))
207 return false;
208
209 return true;
210}
211
212/* Check to see if two extent_map structs are adjacent and safe to merge. */
213static bool mergeable_maps(const struct extent_map *prev, const struct extent_map *next)
214{
215 if (extent_map_end(prev) != next->start)
216 return false;
217
218 if (prev->flags != next->flags)
219 return false;
220
221 if (next->block_start < EXTENT_MAP_LAST_BYTE - 1)
222 return next->block_start == extent_map_block_end(prev);
223
224 /* HOLES and INLINE extents. */
225 return next->block_start == prev->block_start;
226}
227
228static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
229{
230 struct extent_map *merge = NULL;
231 struct rb_node *rb;
232
233 /*
234 * We can't modify an extent map that is in the tree and that is being
235 * used by another task, as it can cause that other task to see it in
236 * inconsistent state during the merging. We always have 1 reference for
237 * the tree and 1 for this task (which is unpinning the extent map or
238 * clearing the logging flag), so anything > 2 means it's being used by
239 * other tasks too.
240 */
241 if (refcount_read(&em->refs) > 2)
242 return;
243
244 if (!can_merge_extent_map(em))
245 return;
246
247 if (em->start != 0) {
248 rb = rb_prev(&em->rb_node);
249 if (rb)
250 merge = rb_entry(rb, struct extent_map, rb_node);
251 if (rb && can_merge_extent_map(merge) && mergeable_maps(merge, em)) {
252 em->start = merge->start;
253 em->orig_start = merge->orig_start;
254 em->len += merge->len;
255 em->block_len += merge->block_len;
256 em->block_start = merge->block_start;
257 em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
258 em->mod_start = merge->mod_start;
259 em->generation = max(em->generation, merge->generation);
260 em->flags |= EXTENT_FLAG_MERGED;
261
262 rb_erase_cached(&merge->rb_node, &tree->map);
263 RB_CLEAR_NODE(&merge->rb_node);
264 free_extent_map(merge);
265 }
266 }
267
268 rb = rb_next(&em->rb_node);
269 if (rb)
270 merge = rb_entry(rb, struct extent_map, rb_node);
271 if (rb && can_merge_extent_map(merge) && mergeable_maps(em, merge)) {
272 em->len += merge->len;
273 em->block_len += merge->block_len;
274 rb_erase_cached(&merge->rb_node, &tree->map);
275 RB_CLEAR_NODE(&merge->rb_node);
276 em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
277 em->generation = max(em->generation, merge->generation);
278 em->flags |= EXTENT_FLAG_MERGED;
279 free_extent_map(merge);
280 }
281}
282
283/*
284 * Unpin an extent from the cache.
285 *
286 * @inode: the inode from which we are unpinning an extent range
287 * @start: logical offset in the file
288 * @len: length of the extent
289 * @gen: generation that this extent has been modified in
290 *
291 * Called after an extent has been written to disk properly. Set the generation
292 * to the generation that actually added the file item to the inode so we know
293 * we need to sync this extent when we call fsync().
294 */
295int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen)
296{
297 struct btrfs_fs_info *fs_info = inode->root->fs_info;
298 struct extent_map_tree *tree = &inode->extent_tree;
299 int ret = 0;
300 struct extent_map *em;
301 bool prealloc = false;
302
303 write_lock(&tree->lock);
304 em = lookup_extent_mapping(tree, start, len);
305
306 if (WARN_ON(!em)) {
307 btrfs_warn(fs_info,
308"no extent map found for inode %llu (root %lld) when unpinning extent range [%llu, %llu), generation %llu",
309 btrfs_ino(inode), btrfs_root_id(inode->root),
310 start, len, gen);
311 goto out;
312 }
313
314 if (WARN_ON(em->start != start))
315 btrfs_warn(fs_info,
316"found extent map for inode %llu (root %lld) with unexpected start offset %llu when unpinning extent range [%llu, %llu), generation %llu",
317 btrfs_ino(inode), btrfs_root_id(inode->root),
318 em->start, start, len, gen);
319
320 em->generation = gen;
321 em->flags &= ~EXTENT_FLAG_PINNED;
322 em->mod_start = em->start;
323 em->mod_len = em->len;
324
325 if (em->flags & EXTENT_FLAG_FILLING) {
326 prealloc = true;
327 em->flags &= ~EXTENT_FLAG_FILLING;
328 }
329
330 try_merge_map(tree, em);
331
332 if (prealloc) {
333 em->mod_start = em->start;
334 em->mod_len = em->len;
335 }
336
337 free_extent_map(em);
338out:
339 write_unlock(&tree->lock);
340 return ret;
341
342}
343
344void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
345{
346 lockdep_assert_held_write(&tree->lock);
347
348 em->flags &= ~EXTENT_FLAG_LOGGING;
349 if (extent_map_in_tree(em))
350 try_merge_map(tree, em);
351}
352
353static inline void setup_extent_mapping(struct extent_map_tree *tree,
354 struct extent_map *em,
355 int modified)
356{
357 refcount_inc(&em->refs);
358 em->mod_start = em->start;
359 em->mod_len = em->len;
360
361 ASSERT(list_empty(&em->list));
362
363 if (modified)
364 list_add(&em->list, &tree->modified_extents);
365 else
366 try_merge_map(tree, em);
367}
368
369/*
370 * Add new extent map to the extent tree
371 *
372 * @tree: tree to insert new map in
373 * @em: map to insert
374 * @modified: indicate whether the given @em should be added to the
375 * modified list, which indicates the extent needs to be logged
376 *
377 * Insert @em into @tree or perform a simple forward/backward merge with
378 * existing mappings. The extent_map struct passed in will be inserted
379 * into the tree directly, with an additional reference taken, or a
380 * reference dropped if the merge attempt was successful.
381 */
382static int add_extent_mapping(struct extent_map_tree *tree,
383 struct extent_map *em, int modified)
384{
385 int ret = 0;
386
387 lockdep_assert_held_write(&tree->lock);
388
389 ret = tree_insert(&tree->map, em);
390 if (ret)
391 goto out;
392
393 setup_extent_mapping(tree, em, modified);
394out:
395 return ret;
396}
397
398static struct extent_map *
399__lookup_extent_mapping(struct extent_map_tree *tree,
400 u64 start, u64 len, int strict)
401{
402 struct extent_map *em;
403 struct rb_node *rb_node;
404 struct rb_node *prev_or_next = NULL;
405 u64 end = range_end(start, len);
406
407 rb_node = __tree_search(&tree->map.rb_root, start, &prev_or_next);
408 if (!rb_node) {
409 if (prev_or_next)
410 rb_node = prev_or_next;
411 else
412 return NULL;
413 }
414
415 em = rb_entry(rb_node, struct extent_map, rb_node);
416
417 if (strict && !(end > em->start && start < extent_map_end(em)))
418 return NULL;
419
420 refcount_inc(&em->refs);
421 return em;
422}
423
424/*
425 * Lookup extent_map that intersects @start + @len range.
426 *
427 * @tree: tree to lookup in
428 * @start: byte offset to start the search
429 * @len: length of the lookup range
430 *
431 * Find and return the first extent_map struct in @tree that intersects the
432 * [start, len] range. There may be additional objects in the tree that
433 * intersect, so check the object returned carefully to make sure that no
434 * additional lookups are needed.
435 */
436struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
437 u64 start, u64 len)
438{
439 return __lookup_extent_mapping(tree, start, len, 1);
440}
441
442/*
443 * Find a nearby extent map intersecting @start + @len (not an exact search).
444 *
445 * @tree: tree to lookup in
446 * @start: byte offset to start the search
447 * @len: length of the lookup range
448 *
449 * Find and return the first extent_map struct in @tree that intersects the
450 * [start, len] range.
451 *
452 * If one can't be found, any nearby extent may be returned
453 */
454struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
455 u64 start, u64 len)
456{
457 return __lookup_extent_mapping(tree, start, len, 0);
458}
459
460/*
461 * Remove an extent_map from the extent tree.
462 *
463 * @tree: extent tree to remove from
464 * @em: extent map being removed
465 *
466 * Remove @em from @tree. No reference counts are dropped, and no checks
467 * are done to see if the range is in use.
468 */
469void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
470{
471 lockdep_assert_held_write(&tree->lock);
472
473 WARN_ON(em->flags & EXTENT_FLAG_PINNED);
474 rb_erase_cached(&em->rb_node, &tree->map);
475 if (!(em->flags & EXTENT_FLAG_LOGGING))
476 list_del_init(&em->list);
477 RB_CLEAR_NODE(&em->rb_node);
478}
479
480static void replace_extent_mapping(struct extent_map_tree *tree,
481 struct extent_map *cur,
482 struct extent_map *new,
483 int modified)
484{
485 lockdep_assert_held_write(&tree->lock);
486
487 WARN_ON(cur->flags & EXTENT_FLAG_PINNED);
488 ASSERT(extent_map_in_tree(cur));
489 if (!(cur->flags & EXTENT_FLAG_LOGGING))
490 list_del_init(&cur->list);
491 rb_replace_node_cached(&cur->rb_node, &new->rb_node, &tree->map);
492 RB_CLEAR_NODE(&cur->rb_node);
493
494 setup_extent_mapping(tree, new, modified);
495}
496
497static struct extent_map *next_extent_map(const struct extent_map *em)
498{
499 struct rb_node *next;
500
501 next = rb_next(&em->rb_node);
502 if (!next)
503 return NULL;
504 return container_of(next, struct extent_map, rb_node);
505}
506
507static struct extent_map *prev_extent_map(struct extent_map *em)
508{
509 struct rb_node *prev;
510
511 prev = rb_prev(&em->rb_node);
512 if (!prev)
513 return NULL;
514 return container_of(prev, struct extent_map, rb_node);
515}
516
517/*
518 * Helper for btrfs_get_extent. Given an existing extent in the tree,
519 * the existing extent is the nearest extent to map_start,
520 * and an extent that you want to insert, deal with overlap and insert
521 * the best fitted new extent into the tree.
522 */
523static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
524 struct extent_map *existing,
525 struct extent_map *em,
526 u64 map_start)
527{
528 struct extent_map *prev;
529 struct extent_map *next;
530 u64 start;
531 u64 end;
532 u64 start_diff;
533
534 BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
535
536 if (existing->start > map_start) {
537 next = existing;
538 prev = prev_extent_map(next);
539 } else {
540 prev = existing;
541 next = next_extent_map(prev);
542 }
543
544 start = prev ? extent_map_end(prev) : em->start;
545 start = max_t(u64, start, em->start);
546 end = next ? next->start : extent_map_end(em);
547 end = min_t(u64, end, extent_map_end(em));
548 start_diff = start - em->start;
549 em->start = start;
550 em->len = end - start;
551 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
552 !extent_map_is_compressed(em)) {
553 em->block_start += start_diff;
554 em->block_len = em->len;
555 }
556 return add_extent_mapping(em_tree, em, 0);
557}
558
559/*
560 * Add extent mapping into em_tree.
561 *
562 * @fs_info: the filesystem
563 * @em_tree: extent tree into which we want to insert the extent mapping
564 * @em_in: extent we are inserting
565 * @start: start of the logical range btrfs_get_extent() is requesting
566 * @len: length of the logical range btrfs_get_extent() is requesting
567 *
568 * Note that @em_in's range may be different from [start, start+len),
569 * but they must be overlapped.
570 *
571 * Insert @em_in into @em_tree. In case there is an overlapping range, handle
572 * the -EEXIST by either:
573 * a) Returning the existing extent in @em_in if @start is within the
574 * existing em.
575 * b) Merge the existing extent with @em_in passed in.
576 *
577 * Return 0 on success, otherwise -EEXIST.
578 *
579 */
580int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
581 struct extent_map_tree *em_tree,
582 struct extent_map **em_in, u64 start, u64 len)
583{
584 int ret;
585 struct extent_map *em = *em_in;
586
587 /*
588 * Tree-checker should have rejected any inline extent with non-zero
589 * file offset. Here just do a sanity check.
590 */
591 if (em->block_start == EXTENT_MAP_INLINE)
592 ASSERT(em->start == 0);
593
594 ret = add_extent_mapping(em_tree, em, 0);
595 /* it is possible that someone inserted the extent into the tree
596 * while we had the lock dropped. It is also possible that
597 * an overlapping map exists in the tree
598 */
599 if (ret == -EEXIST) {
600 struct extent_map *existing;
601
602 existing = search_extent_mapping(em_tree, start, len);
603
604 trace_btrfs_handle_em_exist(fs_info, existing, em, start, len);
605
606 /*
607 * existing will always be non-NULL, since there must be
608 * extent causing the -EEXIST.
609 */
610 if (start >= existing->start &&
611 start < extent_map_end(existing)) {
612 free_extent_map(em);
613 *em_in = existing;
614 ret = 0;
615 } else {
616 u64 orig_start = em->start;
617 u64 orig_len = em->len;
618
619 /*
620 * The existing extent map is the one nearest to
621 * the [start, start + len) range which overlaps
622 */
623 ret = merge_extent_mapping(em_tree, existing,
624 em, start);
625 if (ret) {
626 free_extent_map(em);
627 *em_in = NULL;
628 WARN_ONCE(ret,
629"unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
630 ret, existing->start, existing->len,
631 orig_start, orig_len);
632 }
633 free_extent_map(existing);
634 }
635 }
636
637 ASSERT(ret == 0 || ret == -EEXIST);
638 return ret;
639}
640
641/*
642 * Drop all extent maps from a tree in the fastest possible way, rescheduling
643 * if needed. This avoids searching the tree, from the root down to the first
644 * extent map, before each deletion.
645 */
646static void drop_all_extent_maps_fast(struct extent_map_tree *tree)
647{
648 write_lock(&tree->lock);
649 while (!RB_EMPTY_ROOT(&tree->map.rb_root)) {
650 struct extent_map *em;
651 struct rb_node *node;
652
653 node = rb_first_cached(&tree->map);
654 em = rb_entry(node, struct extent_map, rb_node);
655 em->flags &= ~(EXTENT_FLAG_PINNED | EXTENT_FLAG_LOGGING);
656 remove_extent_mapping(tree, em);
657 free_extent_map(em);
658 cond_resched_rwlock_write(&tree->lock);
659 }
660 write_unlock(&tree->lock);
661}
662
663/*
664 * Drop all extent maps in a given range.
665 *
666 * @inode: The target inode.
667 * @start: Start offset of the range.
668 * @end: End offset of the range (inclusive value).
669 * @skip_pinned: Indicate if pinned extent maps should be ignored or not.
670 *
671 * This drops all the extent maps that intersect the given range [@start, @end].
672 * Extent maps that partially overlap the range and extend behind or beyond it,
673 * are split.
674 * The caller should have locked an appropriate file range in the inode's io
675 * tree before calling this function.
676 */
677void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end,
678 bool skip_pinned)
679{
680 struct extent_map *split;
681 struct extent_map *split2;
682 struct extent_map *em;
683 struct extent_map_tree *em_tree = &inode->extent_tree;
684 u64 len = end - start + 1;
685
686 WARN_ON(end < start);
687 if (end == (u64)-1) {
688 if (start == 0 && !skip_pinned) {
689 drop_all_extent_maps_fast(em_tree);
690 return;
691 }
692 len = (u64)-1;
693 } else {
694 /* Make end offset exclusive for use in the loop below. */
695 end++;
696 }
697
698 /*
699 * It's ok if we fail to allocate the extent maps, see the comment near
700 * the bottom of the loop below. We only need two spare extent maps in
701 * the worst case, where the first extent map that intersects our range
702 * starts before the range and the last extent map that intersects our
703 * range ends after our range (and they might be the same extent map),
704 * because we need to split those two extent maps at the boundaries.
705 */
706 split = alloc_extent_map();
707 split2 = alloc_extent_map();
708
709 write_lock(&em_tree->lock);
710 em = lookup_extent_mapping(em_tree, start, len);
711
712 while (em) {
713 /* extent_map_end() returns exclusive value (last byte + 1). */
714 const u64 em_end = extent_map_end(em);
715 struct extent_map *next_em = NULL;
716 u64 gen;
717 unsigned long flags;
718 bool modified;
719 bool compressed;
720
721 if (em_end < end) {
722 next_em = next_extent_map(em);
723 if (next_em) {
724 if (next_em->start < end)
725 refcount_inc(&next_em->refs);
726 else
727 next_em = NULL;
728 }
729 }
730
731 if (skip_pinned && (em->flags & EXTENT_FLAG_PINNED)) {
732 start = em_end;
733 goto next;
734 }
735
736 flags = em->flags;
737 /*
738 * In case we split the extent map, we want to preserve the
739 * EXTENT_FLAG_LOGGING flag on our extent map, but we don't want
740 * it on the new extent maps.
741 */
742 em->flags &= ~(EXTENT_FLAG_PINNED | EXTENT_FLAG_LOGGING);
743 modified = !list_empty(&em->list);
744
745 /*
746 * The extent map does not cross our target range, so no need to
747 * split it, we can remove it directly.
748 */
749 if (em->start >= start && em_end <= end)
750 goto remove_em;
751
752 gen = em->generation;
753 compressed = extent_map_is_compressed(em);
754
755 if (em->start < start) {
756 if (!split) {
757 split = split2;
758 split2 = NULL;
759 if (!split)
760 goto remove_em;
761 }
762 split->start = em->start;
763 split->len = start - em->start;
764
765 if (em->block_start < EXTENT_MAP_LAST_BYTE) {
766 split->orig_start = em->orig_start;
767 split->block_start = em->block_start;
768
769 if (compressed)
770 split->block_len = em->block_len;
771 else
772 split->block_len = split->len;
773 split->orig_block_len = max(split->block_len,
774 em->orig_block_len);
775 split->ram_bytes = em->ram_bytes;
776 } else {
777 split->orig_start = split->start;
778 split->block_len = 0;
779 split->block_start = em->block_start;
780 split->orig_block_len = 0;
781 split->ram_bytes = split->len;
782 }
783
784 split->generation = gen;
785 split->flags = flags;
786 replace_extent_mapping(em_tree, em, split, modified);
787 free_extent_map(split);
788 split = split2;
789 split2 = NULL;
790 }
791 if (em_end > end) {
792 if (!split) {
793 split = split2;
794 split2 = NULL;
795 if (!split)
796 goto remove_em;
797 }
798 split->start = end;
799 split->len = em_end - end;
800 split->block_start = em->block_start;
801 split->flags = flags;
802 split->generation = gen;
803
804 if (em->block_start < EXTENT_MAP_LAST_BYTE) {
805 split->orig_block_len = max(em->block_len,
806 em->orig_block_len);
807
808 split->ram_bytes = em->ram_bytes;
809 if (compressed) {
810 split->block_len = em->block_len;
811 split->orig_start = em->orig_start;
812 } else {
813 const u64 diff = start + len - em->start;
814
815 split->block_len = split->len;
816 split->block_start += diff;
817 split->orig_start = em->orig_start;
818 }
819 } else {
820 split->ram_bytes = split->len;
821 split->orig_start = split->start;
822 split->block_len = 0;
823 split->orig_block_len = 0;
824 }
825
826 if (extent_map_in_tree(em)) {
827 replace_extent_mapping(em_tree, em, split,
828 modified);
829 } else {
830 int ret;
831
832 ret = add_extent_mapping(em_tree, split,
833 modified);
834 /* Logic error, shouldn't happen. */
835 ASSERT(ret == 0);
836 if (WARN_ON(ret != 0) && modified)
837 btrfs_set_inode_full_sync(inode);
838 }
839 free_extent_map(split);
840 split = NULL;
841 }
842remove_em:
843 if (extent_map_in_tree(em)) {
844 /*
845 * If the extent map is still in the tree it means that
846 * either of the following is true:
847 *
848 * 1) It fits entirely in our range (doesn't end beyond
849 * it or starts before it);
850 *
851 * 2) It starts before our range and/or ends after our
852 * range, and we were not able to allocate the extent
853 * maps for split operations, @split and @split2.
854 *
855 * If we are at case 2) then we just remove the entire
856 * extent map - this is fine since if anyone needs it to
857 * access the subranges outside our range, will just
858 * load it again from the subvolume tree's file extent
859 * item. However if the extent map was in the list of
860 * modified extents, then we must mark the inode for a
861 * full fsync, otherwise a fast fsync will miss this
862 * extent if it's new and needs to be logged.
863 */
864 if ((em->start < start || em_end > end) && modified) {
865 ASSERT(!split);
866 btrfs_set_inode_full_sync(inode);
867 }
868 remove_extent_mapping(em_tree, em);
869 }
870
871 /*
872 * Once for the tree reference (we replaced or removed the
873 * extent map from the tree).
874 */
875 free_extent_map(em);
876next:
877 /* Once for us (for our lookup reference). */
878 free_extent_map(em);
879
880 em = next_em;
881 }
882
883 write_unlock(&em_tree->lock);
884
885 free_extent_map(split);
886 free_extent_map(split2);
887}
888
889/*
890 * Replace a range in the inode's extent map tree with a new extent map.
891 *
892 * @inode: The target inode.
893 * @new_em: The new extent map to add to the inode's extent map tree.
894 * @modified: Indicate if the new extent map should be added to the list of
895 * modified extents (for fast fsync tracking).
896 *
897 * Drops all the extent maps in the inode's extent map tree that intersect the
898 * range of the new extent map and adds the new extent map to the tree.
899 * The caller should have locked an appropriate file range in the inode's io
900 * tree before calling this function.
901 */
902int btrfs_replace_extent_map_range(struct btrfs_inode *inode,
903 struct extent_map *new_em,
904 bool modified)
905{
906 const u64 end = new_em->start + new_em->len - 1;
907 struct extent_map_tree *tree = &inode->extent_tree;
908 int ret;
909
910 ASSERT(!extent_map_in_tree(new_em));
911
912 /*
913 * The caller has locked an appropriate file range in the inode's io
914 * tree, but getting -EEXIST when adding the new extent map can still
915 * happen in case there are extents that partially cover the range, and
916 * this is due to two tasks operating on different parts of the extent.
917 * See commit 18e83ac75bfe67 ("Btrfs: fix unexpected EEXIST from
918 * btrfs_get_extent") for an example and details.
919 */
920 do {
921 btrfs_drop_extent_map_range(inode, new_em->start, end, false);
922 write_lock(&tree->lock);
923 ret = add_extent_mapping(tree, new_em, modified);
924 write_unlock(&tree->lock);
925 } while (ret == -EEXIST);
926
927 return ret;
928}
929
930/*
931 * Split off the first pre bytes from the extent_map at [start, start + len],
932 * and set the block_start for it to new_logical.
933 *
934 * This function is used when an ordered_extent needs to be split.
935 */
936int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
937 u64 new_logical)
938{
939 struct extent_map_tree *em_tree = &inode->extent_tree;
940 struct extent_map *em;
941 struct extent_map *split_pre = NULL;
942 struct extent_map *split_mid = NULL;
943 int ret = 0;
944 unsigned long flags;
945
946 ASSERT(pre != 0);
947 ASSERT(pre < len);
948
949 split_pre = alloc_extent_map();
950 if (!split_pre)
951 return -ENOMEM;
952 split_mid = alloc_extent_map();
953 if (!split_mid) {
954 ret = -ENOMEM;
955 goto out_free_pre;
956 }
957
958 lock_extent(&inode->io_tree, start, start + len - 1, NULL);
959 write_lock(&em_tree->lock);
960 em = lookup_extent_mapping(em_tree, start, len);
961 if (!em) {
962 ret = -EIO;
963 goto out_unlock;
964 }
965
966 ASSERT(em->len == len);
967 ASSERT(!extent_map_is_compressed(em));
968 ASSERT(em->block_start < EXTENT_MAP_LAST_BYTE);
969 ASSERT(em->flags & EXTENT_FLAG_PINNED);
970 ASSERT(!(em->flags & EXTENT_FLAG_LOGGING));
971 ASSERT(!list_empty(&em->list));
972
973 flags = em->flags;
974 em->flags &= ~EXTENT_FLAG_PINNED;
975
976 /* First, replace the em with a new extent_map starting from * em->start */
977 split_pre->start = em->start;
978 split_pre->len = pre;
979 split_pre->orig_start = split_pre->start;
980 split_pre->block_start = new_logical;
981 split_pre->block_len = split_pre->len;
982 split_pre->orig_block_len = split_pre->block_len;
983 split_pre->ram_bytes = split_pre->len;
984 split_pre->flags = flags;
985 split_pre->generation = em->generation;
986
987 replace_extent_mapping(em_tree, em, split_pre, 1);
988
989 /*
990 * Now we only have an extent_map at:
991 * [em->start, em->start + pre]
992 */
993
994 /* Insert the middle extent_map. */
995 split_mid->start = em->start + pre;
996 split_mid->len = em->len - pre;
997 split_mid->orig_start = split_mid->start;
998 split_mid->block_start = em->block_start + pre;
999 split_mid->block_len = split_mid->len;
1000 split_mid->orig_block_len = split_mid->block_len;
1001 split_mid->ram_bytes = split_mid->len;
1002 split_mid->flags = flags;
1003 split_mid->generation = em->generation;
1004 add_extent_mapping(em_tree, split_mid, 1);
1005
1006 /* Once for us */
1007 free_extent_map(em);
1008 /* Once for the tree */
1009 free_extent_map(em);
1010
1011out_unlock:
1012 write_unlock(&em_tree->lock);
1013 unlock_extent(&inode->io_tree, start, start + len - 1, NULL);
1014 free_extent_map(split_mid);
1015out_free_pre:
1016 free_extent_map(split_pre);
1017 return ret;
1018}