1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 2011 STRATO. All rights reserved. 4 */ 5 6 #ifndef BTRFS_BACKREF_H 7 #define BTRFS_BACKREF_H 8 9 #include <linux/types.h> 10 #include <linux/rbtree.h> 11 #include <linux/list.h> 12 #include <linux/slab.h> 13 #include <uapi/linux/btrfs.h> 14 #include <uapi/linux/btrfs_tree.h> 15 #include "messages.h" 16 #include "locking.h" 17 #include "disk-io.h" 18 #include "extent_io.h" 19 #include "ctree.h" 20 21 struct extent_inode_elem; 22 struct ulist; 23 struct btrfs_extent_item; 24 struct btrfs_trans_handle; 25 struct btrfs_fs_info; 26 27 /* 28 * Used by implementations of iterate_extent_inodes_t (see definition below) to 29 * signal that backref iteration can stop immediately and no error happened. 30 * The value must be non-negative and must not be 0, 1 (which is a common return 31 * value from things like btrfs_search_slot() and used internally in the backref 32 * walking code) and different from BACKREF_FOUND_SHARED and 33 * BACKREF_FOUND_NOT_SHARED 34 */ 35 #define BTRFS_ITERATE_EXTENT_INODES_STOP 5 36 37 /* 38 * Should return 0 if no errors happened and iteration of backrefs should 39 * continue. Can return BTRFS_ITERATE_EXTENT_INODES_STOP or any other non-zero 40 * value to immediately stop iteration and possibly signal an error back to 41 * the caller. 42 */ 43 typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 num_bytes, 44 u64 root, void *ctx); 45 46 /* 47 * Context and arguments for backref walking functions. Some of the fields are 48 * to be filled by the caller of such functions while other are filled by the 49 * functions themselves, as described below. 50 */ 51 struct btrfs_backref_walk_ctx { 52 /* 53 * The address of the extent for which we are doing backref walking. 54 * Can be either a data extent or a metadata extent. 55 * 56 * Must always be set by the top level caller. 57 */ 58 u64 bytenr; 59 /* 60 * Offset relative to the target extent. This is only used for data 61 * extents, and it's meaningful because we can have file extent items 62 * that point only to a section of a data extent ("bookend" extents), 63 * and we want to filter out any that don't point to a section of the 64 * data extent containing the given offset. 65 * 66 * Must always be set by the top level caller. 67 */ 68 u64 extent_item_pos; 69 /* 70 * If true and bytenr corresponds to a data extent, then references from 71 * all file extent items that point to the data extent are considered, 72 * @extent_item_pos is ignored. 73 */ 74 bool ignore_extent_item_pos; 75 /* 76 * If true and bytenr corresponds to a data extent, then the inode list 77 * (each member describing inode number, file offset and root) is not 78 * added to each reference added to the @refs ulist. 79 */ 80 bool skip_inode_ref_list; 81 /* A valid transaction handle or NULL. */ 82 struct btrfs_trans_handle *trans; 83 /* 84 * The file system's info object, can not be NULL. 85 * 86 * Must always be set by the top level caller. 87 */ 88 struct btrfs_fs_info *fs_info; 89 /* 90 * Time sequence acquired from btrfs_get_tree_mod_seq(), in case the 91 * caller joined the tree mod log to get a consistent view of b+trees 92 * while we do backref walking, or BTRFS_SEQ_LAST. 93 * When using BTRFS_SEQ_LAST, delayed refs are not checked and it uses 94 * commit roots when searching b+trees - this is a special case for 95 * qgroups used during a transaction commit. 96 */ 97 u64 time_seq; 98 /* 99 * Used to collect the bytenr of metadata extents that point to the 100 * target extent. 101 */ 102 struct ulist *refs; 103 /* 104 * List used to collect the IDs of the roots from which the target 105 * extent is accessible. Can be NULL in case the caller does not care 106 * about collecting root IDs. 107 */ 108 struct ulist *roots; 109 /* 110 * Used by iterate_extent_inodes() and the main backref walk code 111 * (find_parent_nodes()). Lookup and store functions for an optional 112 * cache which maps the logical address (bytenr) of leaves to an array 113 * of root IDs. 114 */ 115 bool (*cache_lookup)(u64 leaf_bytenr, void *user_ctx, 116 const u64 **root_ids_ret, int *root_count_ret); 117 void (*cache_store)(u64 leaf_bytenr, const struct ulist *root_ids, 118 void *user_ctx); 119 /* 120 * If this is not NULL, then the backref walking code will call this 121 * for each indirect data extent reference as soon as it finds one, 122 * before collecting all the remaining backrefs and before resolving 123 * indirect backrefs. This allows for the caller to terminate backref 124 * walking as soon as it finds one backref that matches some specific 125 * criteria. The @cache_lookup and @cache_store callbacks should not 126 * be NULL in order to use this callback. 127 */ 128 iterate_extent_inodes_t *indirect_ref_iterator; 129 /* 130 * If this is not NULL, then the backref walking code will call this for 131 * each extent item it's meant to process before it actually starts 132 * processing it. If this returns anything other than 0, then it stops 133 * the backref walking code immediately. 134 */ 135 int (*check_extent_item)(u64 bytenr, const struct btrfs_extent_item *ei, 136 const struct extent_buffer *leaf, void *user_ctx); 137 /* 138 * If this is not NULL, then the backref walking code will call this for 139 * each extent data ref it finds (BTRFS_EXTENT_DATA_REF_KEY keys) before 140 * processing that data ref. If this callback return false, then it will 141 * ignore this data ref and it will never resolve the indirect data ref, 142 * saving time searching for leaves in a fs tree with file extent items 143 * matching the data ref. 144 */ 145 bool (*skip_data_ref)(u64 root, u64 ino, u64 offset, void *user_ctx); 146 /* Context object to pass to the callbacks defined above. */ 147 void *user_ctx; 148 }; 149 150 struct inode_fs_paths { 151 struct btrfs_path *btrfs_path; 152 struct btrfs_root *fs_root; 153 struct btrfs_data_container *fspath; 154 }; 155 156 struct btrfs_backref_shared_cache_entry { 157 u64 bytenr; 158 u64 gen; 159 bool is_shared; 160 }; 161 162 #define BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE 8 163 164 struct btrfs_backref_share_check_ctx { 165 /* Ulists used during backref walking. */ 166 struct ulist refs; 167 /* 168 * The current leaf the caller of btrfs_is_data_extent_shared() is at. 169 * Typically the caller (at the moment only fiemap) tries to determine 170 * the sharedness of data extents point by file extent items from entire 171 * leaves. 172 */ 173 u64 curr_leaf_bytenr; 174 /* 175 * The previous leaf the caller was at in the previous call to 176 * btrfs_is_data_extent_shared(). This may be the same as the current 177 * leaf. On the first call it must be 0. 178 */ 179 u64 prev_leaf_bytenr; 180 /* 181 * A path from a root to a leaf that has a file extent item pointing to 182 * a given data extent should never exceed the maximum b+tree height. 183 */ 184 struct btrfs_backref_shared_cache_entry path_cache_entries[BTRFS_MAX_LEVEL]; 185 bool use_path_cache; 186 /* 187 * Cache the sharedness result for the last few extents we have found, 188 * but only for extents for which we have multiple file extent items 189 * that point to them. 190 * It's very common to have several file extent items that point to the 191 * same extent (bytenr) but with different offsets and lengths. This 192 * typically happens for COW writes, partial writes into prealloc 193 * extents, NOCOW writes after snapshotting a root, hole punching or 194 * reflinking within the same file (less common perhaps). 195 * So keep a small cache with the lookup results for the extent pointed 196 * by the last few file extent items. This cache is checked, with a 197 * linear scan, whenever btrfs_is_data_extent_shared() is called, so 198 * it must be small so that it does not negatively affect performance in 199 * case we don't have multiple file extent items that point to the same 200 * data extent. 201 */ 202 struct { 203 u64 bytenr; 204 bool is_shared; 205 } prev_extents_cache[BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE]; 206 /* 207 * The slot in the prev_extents_cache array that will be used for 208 * storing the sharedness result of a new data extent. 209 */ 210 int prev_extents_cache_slot; 211 }; 212 213 struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void); 214 void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx); 215 216 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical, 217 struct btrfs_path *path, struct btrfs_key *found_key, 218 u64 *flags); 219 220 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb, 221 struct btrfs_key *key, struct btrfs_extent_item *ei, 222 u32 item_size, u64 *out_root, u8 *out_level); 223 224 int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx, 225 bool search_commit_root, 226 iterate_extent_inodes_t *iterate, void *user_ctx); 227 228 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info, 229 void *ctx, bool ignore_offset); 230 231 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath); 232 233 int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx); 234 int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx, 235 bool skip_commit_root_sem); 236 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path, 237 u32 name_len, unsigned long name_off, 238 struct extent_buffer *eb_in, u64 parent, 239 char *dest, u32 size); 240 241 struct btrfs_data_container *init_data_container(u32 total_bytes); 242 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root, 243 struct btrfs_path *path); 244 245 DEFINE_FREE(inode_fs_paths, struct inode_fs_paths *, 246 if (_T) { 247 kvfree(_T->fspath); 248 kfree(_T); 249 }) 250 251 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid, 252 u64 start_off, struct btrfs_path *path, 253 struct btrfs_inode_extref **ret_extref, 254 u64 *found_off); 255 int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr, 256 u64 extent_gen, 257 struct btrfs_backref_share_check_ctx *ctx); 258 259 int __init btrfs_prelim_ref_init(void); 260 void __cold btrfs_prelim_ref_exit(void); 261 262 struct prelim_ref { 263 struct rb_node rbnode; 264 u64 root_id; 265 struct btrfs_key key_for_search; 266 u8 level; 267 int count; 268 struct extent_inode_elem *inode_list; 269 u64 parent; 270 u64 wanted_disk_byte; 271 }; 272 273 /* 274 * Iterate backrefs of one extent. 275 * 276 * Now it only supports iteration of tree block in commit root. 277 */ 278 struct btrfs_backref_iter { 279 u64 bytenr; 280 struct btrfs_path *path; 281 struct btrfs_fs_info *fs_info; 282 struct btrfs_key cur_key; 283 u32 item_ptr; 284 u32 cur_ptr; 285 u32 end_ptr; 286 }; 287 288 struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info); 289 290 /* 291 * For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data 292 * is btrfs_tree_block_info, without a btrfs_extent_inline_ref header. 293 * 294 * This helper determines if that's the case. 295 */ 296 static inline bool btrfs_backref_has_tree_block_info( 297 struct btrfs_backref_iter *iter) 298 { 299 if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY && 300 iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item)) 301 return true; 302 return false; 303 } 304 305 int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr); 306 307 int btrfs_backref_iter_next(struct btrfs_backref_iter *iter); 308 309 /* 310 * Backref cache related structures 311 * 312 * The whole objective of backref_cache is to build a bi-directional map 313 * of tree blocks (represented by backref_node) and all their parents. 314 */ 315 316 /* 317 * Represent a tree block in the backref cache 318 */ 319 struct btrfs_backref_node { 320 union{ 321 /* Use rb_simple_node for search/insert */ 322 struct { 323 struct rb_node rb_node; 324 u64 bytenr; 325 }; 326 327 struct rb_simple_node simple_node; 328 }; 329 330 /* 331 * This is a sanity check, whenever we COW a block we will update 332 * new_bytenr with it's current location, and we will check this in 333 * various places to validate that the cache makes sense, it shouldn't 334 * be used for anything else. 335 */ 336 u64 new_bytenr; 337 /* Objectid of tree block owner, can be not uptodate */ 338 u64 owner; 339 /* Link to pending, changed or detached list */ 340 struct list_head list; 341 342 /* List of upper level edges, which link this node to its parents */ 343 struct list_head upper; 344 /* List of lower level edges, which link this node to its children */ 345 struct list_head lower; 346 347 /* NULL if this node is not tree root */ 348 struct btrfs_root *root; 349 /* Extent buffer got by COWing the block */ 350 struct extent_buffer *eb; 351 /* Level of the tree block */ 352 unsigned int level:8; 353 /* Is the extent buffer locked */ 354 unsigned int locked:1; 355 /* Has the block been processed */ 356 unsigned int processed:1; 357 /* Have backrefs of this block been checked */ 358 unsigned int checked:1; 359 /* 360 * 1 if corresponding block has been COWed but some upper level block 361 * pointers may not point to the new location 362 */ 363 unsigned int pending:1; 364 /* 1 if the backref node isn't connected to any other backref node */ 365 unsigned int detached:1; 366 367 /* 368 * For generic purpose backref cache, where we only care if it's a reloc 369 * root, doesn't care the source subvolid. 370 */ 371 unsigned int is_reloc_root:1; 372 }; 373 374 #define LOWER 0 375 #define UPPER 1 376 377 /* 378 * Represent an edge connecting upper and lower backref nodes. 379 */ 380 struct btrfs_backref_edge { 381 /* 382 * list[LOWER] is linked to btrfs_backref_node::upper of lower level 383 * node, and list[UPPER] is linked to btrfs_backref_node::lower of 384 * upper level node. 385 * 386 * Also, build_backref_tree() uses list[UPPER] for pending edges, before 387 * linking list[UPPER] to its upper level nodes. 388 */ 389 struct list_head list[2]; 390 391 /* Two related nodes */ 392 struct btrfs_backref_node *node[2]; 393 }; 394 395 struct btrfs_backref_cache { 396 /* Red black tree of all backref nodes in the cache */ 397 struct rb_root rb_root; 398 /* For passing backref nodes to btrfs_reloc_cow_block */ 399 struct btrfs_backref_node *path[BTRFS_MAX_LEVEL]; 400 /* 401 * List of blocks that have been COWed but some block pointers in upper 402 * level blocks may not reflect the new location 403 */ 404 struct list_head pending[BTRFS_MAX_LEVEL]; 405 406 u64 last_trans; 407 408 int nr_nodes; 409 int nr_edges; 410 411 /* List of unchecked backref edges during backref cache build */ 412 struct list_head pending_edge; 413 414 /* List of useless backref nodes during backref cache build */ 415 struct list_head useless_node; 416 417 struct btrfs_fs_info *fs_info; 418 419 /* 420 * Whether this cache is for relocation 421 * 422 * Relocation backref cache require more info for reloc root compared 423 * to generic backref cache. 424 */ 425 bool is_reloc; 426 }; 427 428 void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info, 429 struct btrfs_backref_cache *cache, bool is_reloc); 430 struct btrfs_backref_node *btrfs_backref_alloc_node( 431 struct btrfs_backref_cache *cache, u64 bytenr, int level); 432 struct btrfs_backref_edge *btrfs_backref_alloc_edge( 433 struct btrfs_backref_cache *cache); 434 435 void btrfs_backref_free_node(struct btrfs_backref_cache *cache, 436 struct btrfs_backref_node *node); 437 void btrfs_backref_free_edge(struct btrfs_backref_cache *cache, 438 struct btrfs_backref_edge *edge); 439 void btrfs_backref_unlock_node_buffer(struct btrfs_backref_node *node); 440 void btrfs_backref_drop_node_buffer(struct btrfs_backref_node *node); 441 442 void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache, 443 struct btrfs_backref_node *node); 444 void btrfs_backref_drop_node(struct btrfs_backref_cache *tree, 445 struct btrfs_backref_node *node); 446 447 void btrfs_backref_release_cache(struct btrfs_backref_cache *cache); 448 449 static inline void btrfs_backref_panic(struct btrfs_fs_info *fs_info, 450 u64 bytenr, int error) 451 { 452 btrfs_panic(fs_info, error, 453 "Inconsistency in backref cache found at offset %llu", 454 bytenr); 455 } 456 457 int btrfs_backref_add_tree_node(struct btrfs_trans_handle *trans, 458 struct btrfs_backref_cache *cache, 459 struct btrfs_path *path, 460 struct btrfs_backref_iter *iter, 461 struct btrfs_key *node_key, 462 struct btrfs_backref_node *cur); 463 464 int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache, 465 struct btrfs_backref_node *start); 466 467 void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache, 468 struct btrfs_backref_node *node); 469 470 #endif 471