mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race
[linux/fpc-iii.git] / fs / btrfs / extent_map.c
blobc87d673ce3347c0cb755f0abeb8fefb00af7c835
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/err.h>
3 #include <linux/slab.h>
4 #include <linux/spinlock.h>
5 #include <linux/hardirq.h>
6 #include "ctree.h"
7 #include "extent_map.h"
8 #include "compression.h"
11 static struct kmem_cache *extent_map_cache;
13 int __init extent_map_init(void)
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;
23 void extent_map_exit(void)
25 kmem_cache_destroy(extent_map_cache);
28 /**
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)
37 tree->map = RB_ROOT;
38 INIT_LIST_HEAD(&tree->modified_extents);
39 rwlock_init(&tree->lock);
42 /**
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_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;
64 /**
65 * free_extent_map - drop reference count of an extent_map
66 * @em: extent map being released
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)
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);
85 /* simple helper to do math around the end of an extent, handling wrap */
86 static u64 range_end(u64 start, u64 len)
88 if (start + len < start)
89 return (u64)-1;
90 return start + len;
93 static int tree_insert(struct rb_root *root, struct extent_map *em)
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);
101 while (*p) {
102 parent = *p;
103 entry = rb_entry(parent, struct extent_map, rb_node);
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;
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);
118 if (parent)
119 if (end > entry->start && em->start < extent_map_end(entry))
120 return -EEXIST;
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);
128 if (parent)
129 if (end > entry->start && em->start < extent_map_end(entry))
130 return -EEXIST;
132 rb_link_node(&em->rb_node, orig_parent, p);
133 rb_insert_color(&em->rb_node, root);
134 return 0;
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
141 static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
142 struct rb_node **prev_ret,
143 struct rb_node **next_ret)
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;
151 while (n) {
152 entry = rb_entry(n, struct extent_map, rb_node);
153 prev = n;
154 prev_entry = entry;
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;
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);
170 *prev_ret = prev;
171 prev = orig_prev;
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);
180 *next_ret = prev;
182 return NULL;
185 /* check to see if two extent_map structs are adjacent and safe to merge */
186 static int mergable_maps(struct extent_map *prev, struct extent_map *next)
188 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
189 return 0;
192 * don't merge compressed extents, we need to know their
193 * actual size
195 if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
196 return 0;
198 if (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) ||
199 test_bit(EXTENT_FLAG_LOGGING, &next->flags))
200 return 0;
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.
207 if (!list_empty(&prev->list) || !list_empty(&next->list))
208 return 0;
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;
223 return 0;
226 static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
228 struct extent_map *merge = NULL;
229 struct rb_node *rb;
232 * We can't modify an extent map that is in the tree and that is being
233 * used by another task, as it can cause that other task to see it in
234 * inconsistent state during the merging. We always have 1 reference for
235 * the tree and 1 for this task (which is unpinning the extent map or
236 * clearing the logging flag), so anything > 2 means it's being used by
237 * other tasks too.
239 if (refcount_read(&em->refs) > 2)
240 return;
242 if (em->start != 0) {
243 rb = rb_prev(&em->rb_node);
244 if (rb)
245 merge = rb_entry(rb, struct extent_map, rb_node);
246 if (rb && mergable_maps(merge, em)) {
247 em->start = merge->start;
248 em->orig_start = merge->orig_start;
249 em->len += merge->len;
250 em->block_len += merge->block_len;
251 em->block_start = merge->block_start;
252 em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
253 em->mod_start = merge->mod_start;
254 em->generation = max(em->generation, merge->generation);
256 rb_erase(&merge->rb_node, &tree->map);
257 RB_CLEAR_NODE(&merge->rb_node);
258 free_extent_map(merge);
262 rb = rb_next(&em->rb_node);
263 if (rb)
264 merge = rb_entry(rb, struct extent_map, rb_node);
265 if (rb && mergable_maps(em, merge)) {
266 em->len += merge->len;
267 em->block_len += merge->block_len;
268 rb_erase(&merge->rb_node, &tree->map);
269 RB_CLEAR_NODE(&merge->rb_node);
270 em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
271 em->generation = max(em->generation, merge->generation);
272 free_extent_map(merge);
277 * unpin_extent_cache - unpin an extent from the cache
278 * @tree: tree to unpin the extent in
279 * @start: logical offset in the file
280 * @len: length of the extent
281 * @gen: generation that this extent has been modified in
283 * Called after an extent has been written to disk properly. Set the generation
284 * to the generation that actually added the file item to the inode so we know
285 * we need to sync this extent when we call fsync().
287 int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
288 u64 gen)
290 int ret = 0;
291 struct extent_map *em;
292 bool prealloc = false;
294 write_lock(&tree->lock);
295 em = lookup_extent_mapping(tree, start, len);
297 WARN_ON(!em || em->start != start);
299 if (!em)
300 goto out;
302 em->generation = gen;
303 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
304 em->mod_start = em->start;
305 em->mod_len = em->len;
307 if (test_bit(EXTENT_FLAG_FILLING, &em->flags)) {
308 prealloc = true;
309 clear_bit(EXTENT_FLAG_FILLING, &em->flags);
312 try_merge_map(tree, em);
314 if (prealloc) {
315 em->mod_start = em->start;
316 em->mod_len = em->len;
319 free_extent_map(em);
320 out:
321 write_unlock(&tree->lock);
322 return ret;
326 void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
328 clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
329 if (extent_map_in_tree(em))
330 try_merge_map(tree, em);
333 static inline void setup_extent_mapping(struct extent_map_tree *tree,
334 struct extent_map *em,
335 int modified)
337 refcount_inc(&em->refs);
338 em->mod_start = em->start;
339 em->mod_len = em->len;
341 if (modified)
342 list_move(&em->list, &tree->modified_extents);
343 else
344 try_merge_map(tree, em);
348 * add_extent_mapping - add new extent map to the extent tree
349 * @tree: tree to insert new map in
350 * @em: map to insert
352 * Insert @em into @tree or perform a simple forward/backward merge with
353 * existing mappings. The extent_map struct passed in will be inserted
354 * into the tree directly, with an additional reference taken, or a
355 * reference dropped if the merge attempt was successful.
357 int add_extent_mapping(struct extent_map_tree *tree,
358 struct extent_map *em, int modified)
360 int ret = 0;
362 ret = tree_insert(&tree->map, em);
363 if (ret)
364 goto out;
366 setup_extent_mapping(tree, em, modified);
367 out:
368 return ret;
371 static struct extent_map *
372 __lookup_extent_mapping(struct extent_map_tree *tree,
373 u64 start, u64 len, int strict)
375 struct extent_map *em;
376 struct rb_node *rb_node;
377 struct rb_node *prev = NULL;
378 struct rb_node *next = NULL;
379 u64 end = range_end(start, len);
381 rb_node = __tree_search(&tree->map, start, &prev, &next);
382 if (!rb_node) {
383 if (prev)
384 rb_node = prev;
385 else if (next)
386 rb_node = next;
387 else
388 return NULL;
391 em = rb_entry(rb_node, struct extent_map, rb_node);
393 if (strict && !(end > em->start && start < extent_map_end(em)))
394 return NULL;
396 refcount_inc(&em->refs);
397 return em;
401 * lookup_extent_mapping - lookup extent_map
402 * @tree: tree to lookup in
403 * @start: byte offset to start the search
404 * @len: length of the lookup range
406 * Find and return the first extent_map struct in @tree that intersects the
407 * [start, len] range. There may be additional objects in the tree that
408 * intersect, so check the object returned carefully to make sure that no
409 * additional lookups are needed.
411 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
412 u64 start, u64 len)
414 return __lookup_extent_mapping(tree, start, len, 1);
418 * search_extent_mapping - find a nearby extent map
419 * @tree: tree to lookup in
420 * @start: byte offset to start the search
421 * @len: length of the lookup range
423 * Find and return the first extent_map struct in @tree that intersects the
424 * [start, len] range.
426 * If one can't be found, any nearby extent may be returned
428 struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
429 u64 start, u64 len)
431 return __lookup_extent_mapping(tree, start, len, 0);
435 * remove_extent_mapping - removes an extent_map from the extent tree
436 * @tree: extent tree to remove from
437 * @em: extent map being removed
439 * Removes @em from @tree. No reference counts are dropped, and no checks
440 * are done to see if the range is in use
442 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
444 int ret = 0;
446 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
447 rb_erase(&em->rb_node, &tree->map);
448 if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
449 list_del_init(&em->list);
450 RB_CLEAR_NODE(&em->rb_node);
451 return ret;
454 void replace_extent_mapping(struct extent_map_tree *tree,
455 struct extent_map *cur,
456 struct extent_map *new,
457 int modified)
459 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags));
460 ASSERT(extent_map_in_tree(cur));
461 if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags))
462 list_del_init(&cur->list);
463 rb_replace_node(&cur->rb_node, &new->rb_node, &tree->map);
464 RB_CLEAR_NODE(&cur->rb_node);
466 setup_extent_mapping(tree, new, modified);