1 #include <linux/err.h> 2 #include <linux/gfp.h> 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" 9 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 *, 14 unsigned long)); 15 16 static struct kmem_cache *extent_map_cache; 17 18 int __init extent_map_init(void) 19 { 20 extent_map_cache = btrfs_cache_create("extent_map", 21 sizeof(struct extent_map), 0, 22 NULL); 23 if (!extent_map_cache) 24 return -ENOMEM; 25 return 0; 26 } 27 28 void extent_map_exit(void) 29 { 30 if (extent_map_cache) 31 kmem_cache_destroy(extent_map_cache); 32 } 33 34 /** 35 * extent_map_tree_init - initialize extent map tree 36 * @tree: tree to initialize 37 * @mask: flags for memory allocations during tree operations 38 * 39 * Initialize the extent tree @tree. Should be called for each new inode 40 * or other user of the extent_map interface. 41 */ 42 void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask) 43 { 44 tree->map.rb_node = NULL; 45 tree->last = NULL; 46 spin_lock_init(&tree->lock); 47 } 48 EXPORT_SYMBOL(extent_map_tree_init); 49 50 /** 51 * alloc_extent_map - allocate new extent map structure 52 * @mask: memory allocation flags 53 * 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() 57 */ 58 struct extent_map *alloc_extent_map(gfp_t mask) 59 { 60 struct extent_map *em; 61 em = kmem_cache_alloc(extent_map_cache, mask); 62 if (!em || IS_ERR(em)) 63 return em; 64 em->in_tree = 0; 65 em->flags = 0; 66 atomic_set(&em->refs, 1); 67 return em; 68 } 69 EXPORT_SYMBOL(alloc_extent_map); 70 71 /** 72 * free_extent_map - drop reference count of an extent_map 73 * @em: extent map beeing releasead 74 * 75 * Drops the reference out on @em by one and free the structure 76 * if the reference count hits zero. 77 */ 78 void free_extent_map(struct extent_map *em) 79 { 80 if (!em) 81 return; 82 WARN_ON(atomic_read(&em->refs) == 0); 83 if (atomic_dec_and_test(&em->refs)) { 84 WARN_ON(em->in_tree); 85 kmem_cache_free(extent_map_cache, em); 86 } 87 } 88 EXPORT_SYMBOL(free_extent_map); 89 90 static struct rb_node *tree_insert(struct rb_root *root, u64 offset, 91 struct rb_node *node) 92 { 93 struct rb_node ** p = &root->rb_node; 94 struct rb_node * parent = NULL; 95 struct extent_map *entry; 96 97 while(*p) { 98 parent = *p; 99 entry = rb_entry(parent, struct extent_map, rb_node); 100 101 WARN_ON(!entry->in_tree); 102 103 if (offset < entry->start) 104 p = &(*p)->rb_left; 105 else if (offset >= extent_map_end(entry)) 106 p = &(*p)->rb_right; 107 else 108 return parent; 109 } 110 111 entry = rb_entry(node, struct extent_map, rb_node); 112 entry->in_tree = 1; 113 rb_link_node(node, parent, p); 114 rb_insert_color(node, root); 115 return NULL; 116 } 117 118 static struct rb_node *__tree_search(struct rb_root *root, u64 offset, 119 struct rb_node **prev_ret, 120 struct rb_node **next_ret) 121 { 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; 127 128 while(n) { 129 entry = rb_entry(n, struct extent_map, rb_node); 130 prev = n; 131 prev_entry = entry; 132 133 WARN_ON(!entry->in_tree); 134 135 if (offset < entry->start) 136 n = n->rb_left; 137 else if (offset >= extent_map_end(entry)) 138 n = n->rb_right; 139 else 140 return n; 141 } 142 143 if (prev_ret) { 144 orig_prev = prev; 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); 148 } 149 *prev_ret = prev; 150 prev = orig_prev; 151 } 152 153 if (next_ret) { 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); 158 } 159 *next_ret = prev; 160 } 161 return NULL; 162 } 163 164 static inline struct rb_node *tree_search(struct rb_root *root, u64 offset) 165 { 166 struct rb_node *prev; 167 struct rb_node *ret; 168 ret = __tree_search(root, offset, &prev, NULL); 169 if (!ret) 170 return prev; 171 return ret; 172 } 173 174 static int mergable_maps(struct extent_map *prev, struct extent_map *next) 175 { 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)))) { 187 return 1; 188 } 189 return 0; 190 } 191 192 /** 193 * add_extent_mapping - add new extent map to the extent tree 194 * @tree: tree to insert new map in 195 * @em: map to insert 196 * 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. 201 */ 202 int add_extent_mapping(struct extent_map_tree *tree, 203 struct extent_map *em) 204 { 205 int ret = 0; 206 struct extent_map *merge = NULL; 207 struct rb_node *rb; 208 209 BUG_ON(spin_trylock(&tree->lock)); 210 rb = tree_insert(&tree->map, em->start, &em->rb_node); 211 if (rb) { 212 ret = -EEXIST; 213 free_extent_map(merge); 214 goto out; 215 } 216 atomic_inc(&em->refs); 217 if (em->start != 0) { 218 rb = rb_prev(&em->rb_node); 219 if (rb) 220 merge = rb_entry(rb, struct extent_map, rb_node); 221 if (rb && mergable_maps(merge, em)) { 222 em->start = merge->start; 223 em->len += merge->len; 224 em->block_start = merge->block_start; 225 merge->in_tree = 0; 226 rb_erase(&merge->rb_node, &tree->map); 227 free_extent_map(merge); 228 } 229 } 230 rb = rb_next(&em->rb_node); 231 if (rb) 232 merge = rb_entry(rb, struct extent_map, rb_node); 233 if (rb && mergable_maps(em, merge)) { 234 em->len += merge->len; 235 rb_erase(&merge->rb_node, &tree->map); 236 merge->in_tree = 0; 237 free_extent_map(merge); 238 } 239 tree->last = em; 240 out: 241 return ret; 242 } 243 EXPORT_SYMBOL(add_extent_mapping); 244 245 static u64 range_end(u64 start, u64 len) 246 { 247 if (start + len < start) 248 return (u64)-1; 249 return start + len; 250 } 251 252 /** 253 * lookup_extent_mapping - lookup extent_map 254 * @tree: tree to lookup in 255 * @start: byte offset to start the search 256 * @len: length of the lookup range 257 * 258 * Find and return the first extent_map struct in @tree that intersects the 259 * [start, len] range. There may be additional objects in the tree that 260 * intersect, so check the object returned carefully to make sure that no 261 * additional lookups are needed. 262 */ 263 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree, 264 u64 start, u64 len) 265 { 266 struct extent_map *em; 267 struct rb_node *rb_node; 268 struct rb_node *prev = NULL; 269 struct rb_node *next = NULL; 270 u64 end = range_end(start, len); 271 272 BUG_ON(spin_trylock(&tree->lock)); 273 em = tree->last; 274 if (em && end > em->start && start < extent_map_end(em)) 275 goto found; 276 277 rb_node = __tree_search(&tree->map, start, &prev, &next); 278 if (!rb_node && prev) { 279 em = rb_entry(prev, struct extent_map, rb_node); 280 if (end > em->start && start < extent_map_end(em)) 281 goto found; 282 } 283 if (!rb_node && next) { 284 em = rb_entry(next, struct extent_map, rb_node); 285 if (end > em->start && start < extent_map_end(em)) 286 goto found; 287 } 288 if (!rb_node) { 289 em = NULL; 290 goto out; 291 } 292 if (IS_ERR(rb_node)) { 293 em = ERR_PTR(PTR_ERR(rb_node)); 294 goto out; 295 } 296 em = rb_entry(rb_node, struct extent_map, rb_node); 297 if (end > em->start && start < extent_map_end(em)) 298 goto found; 299 300 em = NULL; 301 goto out; 302 303 found: 304 atomic_inc(&em->refs); 305 tree->last = em; 306 out: 307 return em; 308 } 309 EXPORT_SYMBOL(lookup_extent_mapping); 310 311 /** 312 * remove_extent_mapping - removes an extent_map from the extent tree 313 * @tree: extent tree to remove from 314 * @em: extent map beeing removed 315 * 316 * Removes @em from @tree. No reference counts are dropped, and no checks 317 * are done to see if the range is in use 318 */ 319 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em) 320 { 321 int ret = 0; 322 323 BUG_ON(spin_trylock(&tree->lock)); 324 rb_erase(&em->rb_node, &tree->map); 325 em->in_tree = 0; 326 if (tree->last == em) 327 tree->last = NULL; 328 return ret; 329 } 330 EXPORT_SYMBOL(remove_extent_mapping); 331