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 void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask) 35 { 36 tree->map.rb_node = NULL; 37 tree->last = NULL; 38 spin_lock_init(&tree->lock); 39 } 40 EXPORT_SYMBOL(extent_map_tree_init); 41 42 struct extent_map *alloc_extent_map(gfp_t mask) 43 { 44 struct extent_map *em; 45 em = kmem_cache_alloc(extent_map_cache, mask); 46 if (!em || IS_ERR(em)) 47 return em; 48 em->in_tree = 0; 49 em->flags = 0; 50 atomic_set(&em->refs, 1); 51 return em; 52 } 53 EXPORT_SYMBOL(alloc_extent_map); 54 55 void free_extent_map(struct extent_map *em) 56 { 57 if (!em) 58 return; 59 WARN_ON(atomic_read(&em->refs) == 0); 60 if (atomic_dec_and_test(&em->refs)) { 61 WARN_ON(em->in_tree); 62 kmem_cache_free(extent_map_cache, em); 63 } 64 } 65 EXPORT_SYMBOL(free_extent_map); 66 67 static struct rb_node *tree_insert(struct rb_root *root, u64 offset, 68 struct rb_node *node) 69 { 70 struct rb_node ** p = &root->rb_node; 71 struct rb_node * parent = NULL; 72 struct extent_map *entry; 73 74 while(*p) { 75 parent = *p; 76 entry = rb_entry(parent, struct extent_map, rb_node); 77 78 WARN_ON(!entry->in_tree); 79 80 if (offset < entry->start) 81 p = &(*p)->rb_left; 82 else if (offset >= extent_map_end(entry)) 83 p = &(*p)->rb_right; 84 else 85 return parent; 86 } 87 88 entry = rb_entry(node, struct extent_map, rb_node); 89 entry->in_tree = 1; 90 rb_link_node(node, parent, p); 91 rb_insert_color(node, root); 92 return NULL; 93 } 94 95 static struct rb_node *__tree_search(struct rb_root *root, u64 offset, 96 struct rb_node **prev_ret, 97 struct rb_node **next_ret) 98 { 99 struct rb_node * n = root->rb_node; 100 struct rb_node *prev = NULL; 101 struct rb_node *orig_prev = NULL; 102 struct extent_map *entry; 103 struct extent_map *prev_entry = NULL; 104 105 while(n) { 106 entry = rb_entry(n, struct extent_map, rb_node); 107 prev = n; 108 prev_entry = entry; 109 110 WARN_ON(!entry->in_tree); 111 112 if (offset < entry->start) 113 n = n->rb_left; 114 else if (offset >= extent_map_end(entry)) 115 n = n->rb_right; 116 else 117 return n; 118 } 119 120 if (prev_ret) { 121 orig_prev = prev; 122 while(prev && offset >= extent_map_end(prev_entry)) { 123 prev = rb_next(prev); 124 prev_entry = rb_entry(prev, struct extent_map, rb_node); 125 } 126 *prev_ret = prev; 127 prev = orig_prev; 128 } 129 130 if (next_ret) { 131 prev_entry = rb_entry(prev, struct extent_map, rb_node); 132 while(prev && offset < prev_entry->start) { 133 prev = rb_prev(prev); 134 prev_entry = rb_entry(prev, struct extent_map, rb_node); 135 } 136 *next_ret = prev; 137 } 138 return NULL; 139 } 140 141 static inline struct rb_node *tree_search(struct rb_root *root, u64 offset) 142 { 143 struct rb_node *prev; 144 struct rb_node *ret; 145 ret = __tree_search(root, offset, &prev, NULL); 146 if (!ret) 147 return prev; 148 return ret; 149 } 150 151 static int mergable_maps(struct extent_map *prev, struct extent_map *next) 152 { 153 if (extent_map_end(prev) == next->start && 154 prev->flags == next->flags && 155 prev->bdev == next->bdev && 156 ((next->block_start == EXTENT_MAP_HOLE && 157 prev->block_start == EXTENT_MAP_HOLE) || 158 (next->block_start == EXTENT_MAP_INLINE && 159 prev->block_start == EXTENT_MAP_INLINE) || 160 (next->block_start == EXTENT_MAP_DELALLOC && 161 prev->block_start == EXTENT_MAP_DELALLOC) || 162 (next->block_start < EXTENT_MAP_LAST_BYTE - 1 && 163 next->block_start == extent_map_block_end(prev)))) { 164 return 1; 165 } 166 return 0; 167 } 168 169 /* 170 * add_extent_mapping tries a simple forward/backward merge with existing 171 * mappings. The extent_map struct passed in will be inserted into 172 * the tree directly (no copies made, just a reference taken). 173 */ 174 int add_extent_mapping(struct extent_map_tree *tree, 175 struct extent_map *em) 176 { 177 int ret = 0; 178 struct extent_map *merge = NULL; 179 struct rb_node *rb; 180 181 rb = tree_insert(&tree->map, em->start, &em->rb_node); 182 if (rb) { 183 merge = rb_entry(rb, struct extent_map, rb_node); 184 ret = -EEXIST; 185 goto out; 186 } 187 atomic_inc(&em->refs); 188 if (em->start != 0) { 189 rb = rb_prev(&em->rb_node); 190 if (rb) 191 merge = rb_entry(rb, struct extent_map, rb_node); 192 if (rb && mergable_maps(merge, em)) { 193 em->start = merge->start; 194 em->len += merge->len; 195 em->block_start = merge->block_start; 196 merge->in_tree = 0; 197 rb_erase(&merge->rb_node, &tree->map); 198 free_extent_map(merge); 199 } 200 } 201 rb = rb_next(&em->rb_node); 202 if (rb) 203 merge = rb_entry(rb, struct extent_map, rb_node); 204 if (rb && mergable_maps(em, merge)) { 205 em->len += merge->len; 206 rb_erase(&merge->rb_node, &tree->map); 207 merge->in_tree = 0; 208 free_extent_map(merge); 209 } 210 tree->last = em; 211 out: 212 return ret; 213 } 214 EXPORT_SYMBOL(add_extent_mapping); 215 216 static u64 range_end(u64 start, u64 len) 217 { 218 if (start + len < start) 219 return (u64)-1; 220 return start + len; 221 } 222 223 /* 224 * lookup_extent_mapping returns the first extent_map struct in the 225 * tree that intersects the [start, len] range. There may 226 * be additional objects in the tree that intersect, so check the object 227 * returned carefully to make sure you don't need additional lookups. 228 */ 229 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree, 230 u64 start, u64 len) 231 { 232 struct extent_map *em; 233 struct rb_node *rb_node; 234 struct rb_node *prev = NULL; 235 struct rb_node *next = NULL; 236 u64 end = range_end(start, len); 237 238 em = tree->last; 239 if (em && end > em->start && start < extent_map_end(em)) 240 goto found; 241 242 rb_node = __tree_search(&tree->map, start, &prev, &next); 243 if (!rb_node && prev) { 244 em = rb_entry(prev, struct extent_map, rb_node); 245 if (end > em->start && start < extent_map_end(em)) 246 goto found; 247 } 248 if (!rb_node && next) { 249 em = rb_entry(next, struct extent_map, rb_node); 250 if (end > em->start && start < extent_map_end(em)) 251 goto found; 252 } 253 if (!rb_node) { 254 em = NULL; 255 goto out; 256 } 257 if (IS_ERR(rb_node)) { 258 em = ERR_PTR(PTR_ERR(rb_node)); 259 goto out; 260 } 261 em = rb_entry(rb_node, struct extent_map, rb_node); 262 if (end > em->start && start < extent_map_end(em)) 263 goto found; 264 265 em = NULL; 266 goto out; 267 268 found: 269 atomic_inc(&em->refs); 270 tree->last = em; 271 out: 272 return em; 273 } 274 EXPORT_SYMBOL(lookup_extent_mapping); 275 276 /* 277 * removes an extent_map struct from the tree. No reference counts are 278 * dropped, and no checks are done to see if the range is in use 279 */ 280 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em) 281 { 282 int ret = 0; 283 284 rb_erase(&em->rb_node, &tree->map); 285 em->in_tree = 0; 286 if (tree->last == em) 287 tree->last = NULL; 288 return ret; 289 } 290 EXPORT_SYMBOL(remove_extent_mapping); 291