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 spin_lock_init(&tree->lock); 46 } 47 EXPORT_SYMBOL(extent_map_tree_init); 48 49 /** 50 * alloc_extent_map - allocate new extent map structure 51 * @mask: memory allocation flags 52 * 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() 56 */ 57 struct extent_map *alloc_extent_map(gfp_t mask) 58 { 59 struct extent_map *em; 60 em = kmem_cache_alloc(extent_map_cache, mask); 61 if (!em || IS_ERR(em)) 62 return em; 63 em->in_tree = 0; 64 em->flags = 0; 65 atomic_set(&em->refs, 1); 66 return em; 67 } 68 EXPORT_SYMBOL(alloc_extent_map); 69 70 /** 71 * free_extent_map - drop reference count of an extent_map 72 * @em: extent map beeing releasead 73 * 74 * Drops the reference out on @em by one and free the structure 75 * if the reference count hits zero. 76 */ 77 void free_extent_map(struct extent_map *em) 78 { 79 if (!em) 80 return; 81 WARN_ON(atomic_read(&em->refs) == 0); 82 if (atomic_dec_and_test(&em->refs)) { 83 WARN_ON(em->in_tree); 84 kmem_cache_free(extent_map_cache, em); 85 } 86 } 87 EXPORT_SYMBOL(free_extent_map); 88 89 static struct rb_node *tree_insert(struct rb_root *root, u64 offset, 90 struct rb_node *node) 91 { 92 struct rb_node ** p = &root->rb_node; 93 struct rb_node * parent = NULL; 94 struct extent_map *entry; 95 96 while(*p) { 97 parent = *p; 98 entry = rb_entry(parent, struct extent_map, rb_node); 99 100 WARN_ON(!entry->in_tree); 101 102 if (offset < entry->start) 103 p = &(*p)->rb_left; 104 else if (offset >= extent_map_end(entry)) 105 p = &(*p)->rb_right; 106 else 107 return parent; 108 } 109 110 entry = rb_entry(node, struct extent_map, rb_node); 111 entry->in_tree = 1; 112 rb_link_node(node, parent, p); 113 rb_insert_color(node, root); 114 return NULL; 115 } 116 117 static struct rb_node *__tree_search(struct rb_root *root, u64 offset, 118 struct rb_node **prev_ret, 119 struct rb_node **next_ret) 120 { 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; 126 127 while(n) { 128 entry = rb_entry(n, struct extent_map, rb_node); 129 prev = n; 130 prev_entry = entry; 131 132 WARN_ON(!entry->in_tree); 133 134 if (offset < entry->start) 135 n = n->rb_left; 136 else if (offset >= extent_map_end(entry)) 137 n = n->rb_right; 138 else 139 return n; 140 } 141 142 if (prev_ret) { 143 orig_prev = prev; 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); 147 } 148 *prev_ret = prev; 149 prev = orig_prev; 150 } 151 152 if (next_ret) { 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); 157 } 158 *next_ret = prev; 159 } 160 return NULL; 161 } 162 163 static inline struct rb_node *tree_search(struct rb_root *root, u64 offset) 164 { 165 struct rb_node *prev; 166 struct rb_node *ret; 167 ret = __tree_search(root, offset, &prev, NULL); 168 if (!ret) 169 return prev; 170 return ret; 171 } 172 173 static int mergable_maps(struct extent_map *prev, struct extent_map *next) 174 { 175 if (test_bit(EXTENT_FLAG_PINNED, &prev->flags)) 176 return 0; 177 178 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)))) { 189 return 1; 190 } 191 return 0; 192 } 193 194 /** 195 * add_extent_mapping - add new extent map to the extent tree 196 * @tree: tree to insert new map in 197 * @em: map to insert 198 * 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. 203 */ 204 int add_extent_mapping(struct extent_map_tree *tree, 205 struct extent_map *em) 206 { 207 int ret = 0; 208 struct extent_map *merge = NULL; 209 struct rb_node *rb; 210 211 BUG_ON(spin_trylock(&tree->lock)); 212 rb = tree_insert(&tree->map, em->start, &em->rb_node); 213 if (rb) { 214 ret = -EEXIST; 215 free_extent_map(merge); 216 goto out; 217 } 218 atomic_inc(&em->refs); 219 if (em->start != 0) { 220 rb = rb_prev(&em->rb_node); 221 if (rb) 222 merge = rb_entry(rb, struct extent_map, rb_node); 223 if (rb && mergable_maps(merge, em)) { 224 em->start = merge->start; 225 em->len += merge->len; 226 em->block_start = merge->block_start; 227 merge->in_tree = 0; 228 rb_erase(&merge->rb_node, &tree->map); 229 free_extent_map(merge); 230 } 231 } 232 rb = rb_next(&em->rb_node); 233 if (rb) 234 merge = rb_entry(rb, struct extent_map, rb_node); 235 if (rb && mergable_maps(em, merge)) { 236 em->len += merge->len; 237 rb_erase(&merge->rb_node, &tree->map); 238 merge->in_tree = 0; 239 free_extent_map(merge); 240 } 241 out: 242 return ret; 243 } 244 EXPORT_SYMBOL(add_extent_mapping); 245 246 static u64 range_end(u64 start, u64 len) 247 { 248 if (start + len < start) 249 return (u64)-1; 250 return start + len; 251 } 252 253 /** 254 * lookup_extent_mapping - lookup extent_map 255 * @tree: tree to lookup in 256 * @start: byte offset to start the search 257 * @len: length of the lookup range 258 * 259 * Find and return the first extent_map struct in @tree that intersects the 260 * [start, len] range. There may be additional objects in the tree that 261 * intersect, so check the object returned carefully to make sure that no 262 * additional lookups are needed. 263 */ 264 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree, 265 u64 start, u64 len) 266 { 267 struct extent_map *em; 268 struct rb_node *rb_node; 269 struct rb_node *prev = NULL; 270 struct rb_node *next = NULL; 271 u64 end = range_end(start, len); 272 273 BUG_ON(spin_trylock(&tree->lock)); 274 rb_node = __tree_search(&tree->map, start, &prev, &next); 275 if (!rb_node && prev) { 276 em = rb_entry(prev, struct extent_map, rb_node); 277 if (end > em->start && start < extent_map_end(em)) 278 goto found; 279 } 280 if (!rb_node && next) { 281 em = rb_entry(next, struct extent_map, rb_node); 282 if (end > em->start && start < extent_map_end(em)) 283 goto found; 284 } 285 if (!rb_node) { 286 em = NULL; 287 goto out; 288 } 289 if (IS_ERR(rb_node)) { 290 em = ERR_PTR(PTR_ERR(rb_node)); 291 goto out; 292 } 293 em = rb_entry(rb_node, struct extent_map, rb_node); 294 if (end > em->start && start < extent_map_end(em)) 295 goto found; 296 297 em = NULL; 298 goto out; 299 300 found: 301 atomic_inc(&em->refs); 302 out: 303 return em; 304 } 305 EXPORT_SYMBOL(lookup_extent_mapping); 306 307 /** 308 * remove_extent_mapping - removes an extent_map from the extent tree 309 * @tree: extent tree to remove from 310 * @em: extent map beeing removed 311 * 312 * Removes @em from @tree. No reference counts are dropped, and no checks 313 * are done to see if the range is in use 314 */ 315 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em) 316 { 317 int ret = 0; 318 319 WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags)); 320 BUG_ON(spin_trylock(&tree->lock)); 321 rb_erase(&em->rb_node, &tree->map); 322 em->in_tree = 0; 323 return ret; 324 } 325 EXPORT_SYMBOL(remove_extent_mapping); 326