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;
45 spin_lock_init(&tree->lock);
47 EXPORT_SYMBOL(extent_map_tree_init);
50 * alloc_extent_map - allocate new extent map structure
51 * @mask: memory allocation flags
53 * Allocate a new extent_map structure. The new structure is
54 * returned with a reference count of one and needs to be
55 * freed using free_extent_map()
57 struct extent_map *alloc_extent_map(gfp_t mask)
59 struct extent_map *em;
60 em = kmem_cache_alloc(extent_map_cache, mask);
61 if (!em || IS_ERR(em))
65 atomic_set(&em->refs, 1);
68 EXPORT_SYMBOL(alloc_extent_map);
71 * free_extent_map - drop reference count of an extent_map
72 * @em: extent map beeing releasead
74 * Drops the reference out on @em by one and free the structure
75 * if the reference count hits zero.
77 void free_extent_map(struct extent_map *em)
81 WARN_ON(atomic_read(&em->refs) == 0);
82 if (atomic_dec_and_test(&em->refs)) {
84 kmem_cache_free(extent_map_cache, em);
87 EXPORT_SYMBOL(free_extent_map);
89 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
92 struct rb_node ** p = &root->rb_node;
93 struct rb_node * parent = NULL;
94 struct extent_map *entry;
98 entry = rb_entry(parent, struct extent_map, rb_node);
100 WARN_ON(!entry->in_tree);
102 if (offset < entry->start)
104 else if (offset >= extent_map_end(entry))
110 entry = rb_entry(node, struct extent_map, rb_node);
112 rb_link_node(node, parent, p);
113 rb_insert_color(node, root);
117 static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
118 struct rb_node **prev_ret,
119 struct rb_node **next_ret)
121 struct rb_node * n = root->rb_node;
122 struct rb_node *prev = NULL;
123 struct rb_node *orig_prev = NULL;
124 struct extent_map *entry;
125 struct extent_map *prev_entry = NULL;
128 entry = rb_entry(n, struct extent_map, rb_node);
132 WARN_ON(!entry->in_tree);
134 if (offset < entry->start)
136 else if (offset >= extent_map_end(entry))
144 while(prev && offset >= extent_map_end(prev_entry)) {
145 prev = rb_next(prev);
146 prev_entry = rb_entry(prev, struct extent_map, rb_node);
153 prev_entry = rb_entry(prev, struct extent_map, rb_node);
154 while(prev && offset < prev_entry->start) {
155 prev = rb_prev(prev);
156 prev_entry = rb_entry(prev, struct extent_map, rb_node);
163 static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
165 struct rb_node *prev;
167 ret = __tree_search(root, offset, &prev, NULL);
173 static int mergable_maps(struct extent_map *prev, struct extent_map *next)
175 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
178 if (extent_map_end(prev) == next->start &&
179 prev->flags == next->flags &&
180 prev->bdev == next->bdev &&
181 ((next->block_start == EXTENT_MAP_HOLE &&
182 prev->block_start == EXTENT_MAP_HOLE) ||
183 (next->block_start == EXTENT_MAP_INLINE &&
184 prev->block_start == EXTENT_MAP_INLINE) ||
185 (next->block_start == EXTENT_MAP_DELALLOC &&
186 prev->block_start == EXTENT_MAP_DELALLOC) ||
187 (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
188 next->block_start == extent_map_block_end(prev)))) {
195 * add_extent_mapping - add new extent map to the extent tree
196 * @tree: tree to insert new map in
199 * Insert @em into @tree or perform a simple forward/backward merge with
200 * existing mappings. The extent_map struct passed in will be inserted
201 * into the tree directly, with an additional reference taken, or a
202 * reference dropped if the merge attempt was sucessfull.
204 int add_extent_mapping(struct extent_map_tree *tree,
205 struct extent_map *em)
208 struct extent_map *merge = NULL;
210 struct extent_map *exist;
212 exist = lookup_extent_mapping(tree, em->start, em->len);
214 free_extent_map(exist);
218 assert_spin_locked(&tree->lock);
219 rb = tree_insert(&tree->map, em->start, &em->rb_node);
222 free_extent_map(merge);
225 atomic_inc(&em->refs);
226 if (em->start != 0) {
227 rb = rb_prev(&em->rb_node);
229 merge = rb_entry(rb, struct extent_map, rb_node);
230 if (rb && mergable_maps(merge, em)) {
231 em->start = merge->start;
232 em->len += merge->len;
233 em->block_start = merge->block_start;
235 rb_erase(&merge->rb_node, &tree->map);
236 free_extent_map(merge);
239 rb = rb_next(&em->rb_node);
241 merge = rb_entry(rb, struct extent_map, rb_node);
242 if (rb && mergable_maps(em, merge)) {
243 em->len += merge->len;
244 rb_erase(&merge->rb_node, &tree->map);
246 free_extent_map(merge);
251 EXPORT_SYMBOL(add_extent_mapping);
253 static u64 range_end(u64 start, u64 len)
255 if (start + len < start)
261 * lookup_extent_mapping - lookup extent_map
262 * @tree: tree to lookup in
263 * @start: byte offset to start the search
264 * @len: length of the lookup range
266 * Find and return the first extent_map struct in @tree that intersects the
267 * [start, len] range. There may be additional objects in the tree that
268 * intersect, so check the object returned carefully to make sure that no
269 * additional lookups are needed.
271 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
274 struct extent_map *em;
275 struct rb_node *rb_node;
276 struct rb_node *prev = NULL;
277 struct rb_node *next = NULL;
278 u64 end = range_end(start, len);
280 assert_spin_locked(&tree->lock);
281 rb_node = __tree_search(&tree->map, start, &prev, &next);
282 if (!rb_node && prev) {
283 em = rb_entry(prev, struct extent_map, rb_node);
284 if (end > em->start && start < extent_map_end(em))
287 if (!rb_node && next) {
288 em = rb_entry(next, struct extent_map, rb_node);
289 if (end > em->start && start < extent_map_end(em))
296 if (IS_ERR(rb_node)) {
297 em = ERR_PTR(PTR_ERR(rb_node));
300 em = rb_entry(rb_node, struct extent_map, rb_node);
301 if (end > em->start && start < extent_map_end(em))
308 atomic_inc(&em->refs);
312 EXPORT_SYMBOL(lookup_extent_mapping);
315 * remove_extent_mapping - removes an extent_map from the extent tree
316 * @tree: extent tree to remove from
317 * @em: extent map beeing removed
319 * Removes @em from @tree. No reference counts are dropped, and no checks
320 * are done to see if the range is in use
322 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
326 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
327 assert_spin_locked(&tree->lock);
328 rb_erase(&em->rb_node, &tree->map);
332 EXPORT_SYMBOL(remove_extent_mapping);