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 spin_lock_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);
159 * look for an offset in the tree, and if it can't be found, return
160 * the first offset we can find smaller than 'offset'.
162 static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
164 struct rb_node *prev;
166 ret = __tree_search(root, offset, &prev, NULL);
172 /* check to see if two extent_map structs are adjacent and safe to merge */
173 static int mergable_maps(struct extent_map *prev, struct extent_map *next)
175 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
179 * don't merge compressed extents, we need to know their
182 if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
185 if (extent_map_end(prev) == next->start &&
186 prev->flags == next->flags &&
187 prev->bdev == next->bdev &&
188 ((next->block_start == EXTENT_MAP_HOLE &&
189 prev->block_start == EXTENT_MAP_HOLE) ||
190 (next->block_start == EXTENT_MAP_INLINE &&
191 prev->block_start == EXTENT_MAP_INLINE) ||
192 (next->block_start == EXTENT_MAP_DELALLOC &&
193 prev->block_start == EXTENT_MAP_DELALLOC) ||
194 (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
195 next->block_start == extent_map_block_end(prev)))) {
202 * add_extent_mapping - add new extent map to the extent tree
203 * @tree: tree to insert new map in
206 * Insert @em into @tree or perform a simple forward/backward merge with
207 * existing mappings. The extent_map struct passed in will be inserted
208 * into the tree directly, with an additional reference taken, or a
209 * reference dropped if the merge attempt was sucessfull.
211 int add_extent_mapping(struct extent_map_tree *tree,
212 struct extent_map *em)
215 struct extent_map *merge = NULL;
217 struct extent_map *exist;
219 exist = lookup_extent_mapping(tree, em->start, em->len);
221 free_extent_map(exist);
225 assert_spin_locked(&tree->lock);
226 rb = tree_insert(&tree->map, em->start, &em->rb_node);
231 atomic_inc(&em->refs);
232 if (em->start != 0) {
233 rb = rb_prev(&em->rb_node);
235 merge = rb_entry(rb, struct extent_map, rb_node);
236 if (rb && mergable_maps(merge, em)) {
237 em->start = merge->start;
238 em->len += merge->len;
239 em->block_len += merge->block_len;
240 em->block_start = merge->block_start;
242 rb_erase(&merge->rb_node, &tree->map);
243 free_extent_map(merge);
246 rb = rb_next(&em->rb_node);
248 merge = rb_entry(rb, struct extent_map, rb_node);
249 if (rb && mergable_maps(em, merge)) {
250 em->len += merge->len;
251 em->block_len += merge->len;
252 rb_erase(&merge->rb_node, &tree->map);
254 free_extent_map(merge);
260 /* simple helper to do math around the end of an extent, handling wrap */
261 static u64 range_end(u64 start, u64 len)
263 if (start + len < start)
269 * lookup_extent_mapping - lookup extent_map
270 * @tree: tree to lookup in
271 * @start: byte offset to start the search
272 * @len: length of the lookup range
274 * Find and return the first extent_map struct in @tree that intersects the
275 * [start, len] range. There may be additional objects in the tree that
276 * intersect, so check the object returned carefully to make sure that no
277 * additional lookups are needed.
279 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
282 struct extent_map *em;
283 struct rb_node *rb_node;
284 struct rb_node *prev = NULL;
285 struct rb_node *next = NULL;
286 u64 end = range_end(start, len);
288 assert_spin_locked(&tree->lock);
289 rb_node = __tree_search(&tree->map, start, &prev, &next);
290 if (!rb_node && prev) {
291 em = rb_entry(prev, struct extent_map, rb_node);
292 if (end > em->start && start < extent_map_end(em))
295 if (!rb_node && next) {
296 em = rb_entry(next, struct extent_map, rb_node);
297 if (end > em->start && start < extent_map_end(em))
304 if (IS_ERR(rb_node)) {
305 em = ERR_PTR(PTR_ERR(rb_node));
308 em = rb_entry(rb_node, struct extent_map, rb_node);
309 if (end > em->start && start < extent_map_end(em))
316 atomic_inc(&em->refs);
322 * remove_extent_mapping - removes an extent_map from the extent tree
323 * @tree: extent tree to remove from
324 * @em: extent map beeing removed
326 * Removes @em from @tree. No reference counts are dropped, and no checks
327 * are done to see if the range is in use
329 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
333 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
334 assert_spin_locked(&tree->lock);
335 rb_erase(&em->rb_node, &tree->map);