3 #include <linux/slab.h>
4 #include <linux/module.h>
5 #include <linux/spinlock.h>
6 #include <linux/hardirq.h>
7 #include "extent_map.h"
10 static struct kmem_cache *extent_map_cache;
12 int __init extent_map_init(void)
14 extent_map_cache = kmem_cache_create("extent_map",
15 sizeof(struct extent_map), 0,
16 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
17 if (!extent_map_cache)
22 void extent_map_exit(void)
25 kmem_cache_destroy(extent_map_cache);
29 * extent_map_tree_init - initialize extent map tree
30 * @tree: tree to initialize
31 * @mask: flags for memory allocations during tree operations
33 * Initialize the extent tree @tree. Should be called for each new inode
34 * or other user of the extent_map interface.
36 void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
38 tree->map.rb_node = NULL;
39 rwlock_init(&tree->lock);
43 * alloc_extent_map - allocate new extent map structure
44 * @mask: memory allocation flags
46 * Allocate a new extent_map structure. The new structure is
47 * returned with a reference count of one and needs to be
48 * freed using free_extent_map()
50 struct extent_map *alloc_extent_map(gfp_t mask)
52 struct extent_map *em;
53 em = kmem_cache_alloc(extent_map_cache, mask);
54 if (!em || IS_ERR(em))
58 atomic_set(&em->refs, 1);
63 * free_extent_map - drop reference count of an extent_map
64 * @em: extent map beeing releasead
66 * Drops the reference out on @em by one and free the structure
67 * if the reference count hits zero.
69 void free_extent_map(struct extent_map *em)
73 WARN_ON(atomic_read(&em->refs) == 0);
74 if (atomic_dec_and_test(&em->refs)) {
76 kmem_cache_free(extent_map_cache, em);
80 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
83 struct rb_node **p = &root->rb_node;
84 struct rb_node *parent = NULL;
85 struct extent_map *entry;
89 entry = rb_entry(parent, struct extent_map, rb_node);
91 WARN_ON(!entry->in_tree);
93 if (offset < entry->start)
95 else if (offset >= extent_map_end(entry))
101 entry = rb_entry(node, struct extent_map, rb_node);
103 rb_link_node(node, parent, p);
104 rb_insert_color(node, root);
109 * search through the tree for an extent_map with a given offset. If
110 * it can't be found, try to find some neighboring extents
112 static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
113 struct rb_node **prev_ret,
114 struct rb_node **next_ret)
116 struct rb_node *n = root->rb_node;
117 struct rb_node *prev = NULL;
118 struct rb_node *orig_prev = NULL;
119 struct extent_map *entry;
120 struct extent_map *prev_entry = NULL;
123 entry = rb_entry(n, struct extent_map, rb_node);
127 WARN_ON(!entry->in_tree);
129 if (offset < entry->start)
131 else if (offset >= extent_map_end(entry))
139 while (prev && offset >= extent_map_end(prev_entry)) {
140 prev = rb_next(prev);
141 prev_entry = rb_entry(prev, struct extent_map, rb_node);
148 prev_entry = rb_entry(prev, struct extent_map, rb_node);
149 while (prev && offset < prev_entry->start) {
150 prev = rb_prev(prev);
151 prev_entry = rb_entry(prev, struct extent_map, rb_node);
158 /* check to see if two extent_map structs are adjacent and safe to merge */
159 static int mergable_maps(struct extent_map *prev, struct extent_map *next)
161 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
165 * don't merge compressed extents, we need to know their
168 if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
171 if (extent_map_end(prev) == next->start &&
172 prev->flags == next->flags &&
173 prev->bdev == next->bdev &&
174 ((next->block_start == EXTENT_MAP_HOLE &&
175 prev->block_start == EXTENT_MAP_HOLE) ||
176 (next->block_start == EXTENT_MAP_INLINE &&
177 prev->block_start == EXTENT_MAP_INLINE) ||
178 (next->block_start == EXTENT_MAP_DELALLOC &&
179 prev->block_start == EXTENT_MAP_DELALLOC) ||
180 (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
181 next->block_start == extent_map_block_end(prev)))) {
187 int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
190 struct extent_map *merge = NULL;
192 struct extent_map *em;
194 write_lock(&tree->lock);
195 em = lookup_extent_mapping(tree, start, len);
197 WARN_ON(!em || em->start != start);
202 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
204 if (em->start != 0) {
205 rb = rb_prev(&em->rb_node);
207 merge = rb_entry(rb, struct extent_map, rb_node);
208 if (rb && mergable_maps(merge, em)) {
209 em->start = merge->start;
210 em->len += merge->len;
211 em->block_len += merge->block_len;
212 em->block_start = merge->block_start;
214 rb_erase(&merge->rb_node, &tree->map);
215 free_extent_map(merge);
219 rb = rb_next(&em->rb_node);
221 merge = rb_entry(rb, struct extent_map, rb_node);
222 if (rb && mergable_maps(em, merge)) {
223 em->len += merge->len;
224 em->block_len += merge->len;
225 rb_erase(&merge->rb_node, &tree->map);
227 free_extent_map(merge);
232 write_unlock(&tree->lock);
238 * add_extent_mapping - add new extent map to the extent tree
239 * @tree: tree to insert new map in
242 * Insert @em into @tree or perform a simple forward/backward merge with
243 * existing mappings. The extent_map struct passed in will be inserted
244 * into the tree directly, with an additional reference taken, or a
245 * reference dropped if the merge attempt was successfull.
247 int add_extent_mapping(struct extent_map_tree *tree,
248 struct extent_map *em)
251 struct extent_map *merge = NULL;
253 struct extent_map *exist;
255 exist = lookup_extent_mapping(tree, em->start, em->len);
257 free_extent_map(exist);
261 rb = tree_insert(&tree->map, em->start, &em->rb_node);
266 atomic_inc(&em->refs);
267 if (em->start != 0) {
268 rb = rb_prev(&em->rb_node);
270 merge = rb_entry(rb, struct extent_map, rb_node);
271 if (rb && mergable_maps(merge, em)) {
272 em->start = merge->start;
273 em->len += merge->len;
274 em->block_len += merge->block_len;
275 em->block_start = merge->block_start;
277 rb_erase(&merge->rb_node, &tree->map);
278 free_extent_map(merge);
281 rb = rb_next(&em->rb_node);
283 merge = rb_entry(rb, struct extent_map, rb_node);
284 if (rb && mergable_maps(em, merge)) {
285 em->len += merge->len;
286 em->block_len += merge->len;
287 rb_erase(&merge->rb_node, &tree->map);
289 free_extent_map(merge);
295 /* simple helper to do math around the end of an extent, handling wrap */
296 static u64 range_end(u64 start, u64 len)
298 if (start + len < start)
304 * lookup_extent_mapping - lookup extent_map
305 * @tree: tree to lookup in
306 * @start: byte offset to start the search
307 * @len: length of the lookup range
309 * Find and return the first extent_map struct in @tree that intersects the
310 * [start, len] range. There may be additional objects in the tree that
311 * intersect, so check the object returned carefully to make sure that no
312 * additional lookups are needed.
314 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
317 struct extent_map *em;
318 struct rb_node *rb_node;
319 struct rb_node *prev = NULL;
320 struct rb_node *next = NULL;
321 u64 end = range_end(start, len);
323 rb_node = __tree_search(&tree->map, start, &prev, &next);
324 if (!rb_node && prev) {
325 em = rb_entry(prev, struct extent_map, rb_node);
326 if (end > em->start && start < extent_map_end(em))
329 if (!rb_node && next) {
330 em = rb_entry(next, struct extent_map, rb_node);
331 if (end > em->start && start < extent_map_end(em))
338 if (IS_ERR(rb_node)) {
339 em = ERR_PTR(PTR_ERR(rb_node));
342 em = rb_entry(rb_node, struct extent_map, rb_node);
343 if (end > em->start && start < extent_map_end(em))
350 atomic_inc(&em->refs);
356 * search_extent_mapping - find a nearby extent map
357 * @tree: tree to lookup in
358 * @start: byte offset to start the search
359 * @len: length of the lookup range
361 * Find and return the first extent_map struct in @tree that intersects the
362 * [start, len] range.
364 * If one can't be found, any nearby extent may be returned
366 struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
369 struct extent_map *em;
370 struct rb_node *rb_node;
371 struct rb_node *prev = NULL;
372 struct rb_node *next = NULL;
374 rb_node = __tree_search(&tree->map, start, &prev, &next);
375 if (!rb_node && prev) {
376 em = rb_entry(prev, struct extent_map, rb_node);
379 if (!rb_node && next) {
380 em = rb_entry(next, struct extent_map, rb_node);
387 if (IS_ERR(rb_node)) {
388 em = ERR_PTR(PTR_ERR(rb_node));
391 em = rb_entry(rb_node, struct extent_map, rb_node);
398 atomic_inc(&em->refs);
404 * remove_extent_mapping - removes an extent_map from the extent tree
405 * @tree: extent tree to remove from
406 * @em: extent map beeing removed
408 * Removes @em from @tree. No reference counts are dropped, and no checks
409 * are done to see if the range is in use
411 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
415 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
416 rb_erase(&em->rb_node, &tree->map);