3 #include <linux/slab.h>
4 #include <linux/module.h>
5 #include <linux/spinlock.h>
6 #include <linux/version.h>
7 #include <linux/hardirq.h>
8 #include "extent_map.h"
10 /* temporary define until extent_map moves out of btrfs */
11 struct kmem_cache *btrfs_cache_create(const char *name, size_t size,
12 unsigned long extra_flags,
13 void (*ctor)(void *, struct kmem_cache *,
16 static struct kmem_cache *extent_map_cache;
18 int __init extent_map_init(void)
20 extent_map_cache = btrfs_cache_create("extent_map",
21 sizeof(struct extent_map), 0,
23 if (!extent_map_cache)
28 void extent_map_exit(void)
31 kmem_cache_destroy(extent_map_cache);
35 * extent_map_tree_init - initialize extent map tree
36 * @tree: tree to initialize
37 * @mask: flags for memory allocations during tree operations
39 * Initialize the extent tree @tree. Should be called for each new inode
40 * or other user of the extent_map interface.
42 void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
44 tree->map.rb_node = NULL;
46 spin_lock_init(&tree->lock);
48 EXPORT_SYMBOL(extent_map_tree_init);
51 * alloc_extent_map - allocate new extent map structure
52 * @mask: memory allocation flags
54 * Allocate a new extent_map structure. The new structure is
55 * returned with a reference count of one and needs to be
56 * freed using free_extent_map()
58 struct extent_map *alloc_extent_map(gfp_t mask)
60 struct extent_map *em;
61 em = kmem_cache_alloc(extent_map_cache, mask);
62 if (!em || IS_ERR(em))
66 atomic_set(&em->refs, 1);
69 EXPORT_SYMBOL(alloc_extent_map);
72 * free_extent_map - drop reference count of an extent_map
73 * @em: extent map beeing releasead
75 * Drops the reference out on @em by one and free the structure
76 * if the reference count hits zero.
78 void free_extent_map(struct extent_map *em)
82 WARN_ON(atomic_read(&em->refs) == 0);
83 if (atomic_dec_and_test(&em->refs)) {
85 kmem_cache_free(extent_map_cache, em);
88 EXPORT_SYMBOL(free_extent_map);
90 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
93 struct rb_node ** p = &root->rb_node;
94 struct rb_node * parent = NULL;
95 struct extent_map *entry;
99 entry = rb_entry(parent, struct extent_map, rb_node);
101 WARN_ON(!entry->in_tree);
103 if (offset < entry->start)
105 else if (offset >= extent_map_end(entry))
111 entry = rb_entry(node, struct extent_map, rb_node);
113 rb_link_node(node, parent, p);
114 rb_insert_color(node, root);
118 static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
119 struct rb_node **prev_ret,
120 struct rb_node **next_ret)
122 struct rb_node * n = root->rb_node;
123 struct rb_node *prev = NULL;
124 struct rb_node *orig_prev = NULL;
125 struct extent_map *entry;
126 struct extent_map *prev_entry = NULL;
129 entry = rb_entry(n, struct extent_map, rb_node);
133 WARN_ON(!entry->in_tree);
135 if (offset < entry->start)
137 else if (offset >= extent_map_end(entry))
145 while(prev && offset >= extent_map_end(prev_entry)) {
146 prev = rb_next(prev);
147 prev_entry = rb_entry(prev, struct extent_map, rb_node);
154 prev_entry = rb_entry(prev, struct extent_map, rb_node);
155 while(prev && offset < prev_entry->start) {
156 prev = rb_prev(prev);
157 prev_entry = rb_entry(prev, struct extent_map, rb_node);
164 static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
166 struct rb_node *prev;
168 ret = __tree_search(root, offset, &prev, NULL);
174 static int mergable_maps(struct extent_map *prev, struct extent_map *next)
176 if (extent_map_end(prev) == next->start &&
177 prev->flags == next->flags &&
178 prev->bdev == next->bdev &&
179 ((next->block_start == EXTENT_MAP_HOLE &&
180 prev->block_start == EXTENT_MAP_HOLE) ||
181 (next->block_start == EXTENT_MAP_INLINE &&
182 prev->block_start == EXTENT_MAP_INLINE) ||
183 (next->block_start == EXTENT_MAP_DELALLOC &&
184 prev->block_start == EXTENT_MAP_DELALLOC) ||
185 (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
186 next->block_start == extent_map_block_end(prev)))) {
193 * add_extent_mapping - add new extent map to the extent tree
194 * @tree: tree to insert new map in
197 * Insert @em into @tree or perform a simple forward/backward merge with
198 * existing mappings. The extent_map struct passed in will be inserted
199 * into the tree directly, with an additional reference taken, or a
200 * reference dropped if the merge attempt was sucessfull.
202 int add_extent_mapping(struct extent_map_tree *tree,
203 struct extent_map *em)
206 struct extent_map *merge = NULL;
209 rb = tree_insert(&tree->map, em->start, &em->rb_node);
211 merge = rb_entry(rb, struct extent_map, rb_node);
215 atomic_inc(&em->refs);
216 if (em->start != 0) {
217 rb = rb_prev(&em->rb_node);
219 merge = rb_entry(rb, struct extent_map, rb_node);
220 if (rb && mergable_maps(merge, em)) {
221 em->start = merge->start;
222 em->len += merge->len;
223 em->block_start = merge->block_start;
225 rb_erase(&merge->rb_node, &tree->map);
226 free_extent_map(merge);
229 rb = rb_next(&em->rb_node);
231 merge = rb_entry(rb, struct extent_map, rb_node);
232 if (rb && mergable_maps(em, merge)) {
233 em->len += merge->len;
234 rb_erase(&merge->rb_node, &tree->map);
236 free_extent_map(merge);
242 EXPORT_SYMBOL(add_extent_mapping);
244 static u64 range_end(u64 start, u64 len)
246 if (start + len < start)
252 * lookup_extent_mapping - lookup extent_map
253 * @tree: tree to lookup in
254 * @start: byte offset to start the search
255 * @len: length of the lookup range
257 * Find and return the first extent_map struct in @tree that intersects the
258 * [start, len] range. There may be additional objects in the tree that
259 * intersect, so check the object returned carefully to make sure that no
260 * additional lookups are needed.
262 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
265 struct extent_map *em;
266 struct rb_node *rb_node;
267 struct rb_node *prev = NULL;
268 struct rb_node *next = NULL;
269 u64 end = range_end(start, len);
272 if (em && end > em->start && start < extent_map_end(em))
275 rb_node = __tree_search(&tree->map, start, &prev, &next);
276 if (!rb_node && prev) {
277 em = rb_entry(prev, struct extent_map, rb_node);
278 if (end > em->start && start < extent_map_end(em))
281 if (!rb_node && next) {
282 em = rb_entry(next, struct extent_map, rb_node);
283 if (end > em->start && start < extent_map_end(em))
290 if (IS_ERR(rb_node)) {
291 em = ERR_PTR(PTR_ERR(rb_node));
294 em = rb_entry(rb_node, struct extent_map, rb_node);
295 if (end > em->start && start < extent_map_end(em))
302 atomic_inc(&em->refs);
307 EXPORT_SYMBOL(lookup_extent_mapping);
310 * remove_extent_mapping - removes an extent_map from the extent tree
311 * @tree: extent tree to remove from
312 * @em: extent map beeing removed
314 * Removes @em from @tree. No reference counts are dropped, and no checks
315 * are done to see if the range is in use
317 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
321 rb_erase(&em->rb_node, &tree->map);
323 if (tree->last == em)
327 EXPORT_SYMBOL(remove_extent_mapping);