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 snapshoting 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 | struct btrfs_path *path, void *ctx, |
230 | bool ignore_offset); |
231 | |
232 | int paths_from_inode(u64 inum, struct inode_fs_paths *ipath); |
233 | |
234 | int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx); |
235 | int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx, |
236 | bool skip_commit_root_sem); |
237 | char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path, |
238 | u32 name_len, unsigned long name_off, |
239 | struct extent_buffer *eb_in, u64 parent, |
240 | char *dest, u32 size); |
241 | |
242 | struct btrfs_data_container *init_data_container(u32 total_bytes); |
243 | struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root, |
244 | struct btrfs_path *path); |
245 | void free_ipath(struct inode_fs_paths *ipath); |
246 | |
247 | int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid, |
248 | u64 start_off, struct btrfs_path *path, |
249 | struct btrfs_inode_extref **ret_extref, |
250 | u64 *found_off); |
251 | int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr, |
252 | u64 extent_gen, |
253 | struct btrfs_backref_share_check_ctx *ctx); |
254 | |
255 | int __init btrfs_prelim_ref_init(void); |
256 | void __cold btrfs_prelim_ref_exit(void); |
257 | |
258 | struct prelim_ref { |
259 | struct rb_node rbnode; |
260 | u64 root_id; |
261 | struct btrfs_key key_for_search; |
262 | u8 level; |
263 | int count; |
264 | struct extent_inode_elem *inode_list; |
265 | u64 parent; |
266 | u64 wanted_disk_byte; |
267 | }; |
268 | |
269 | /* |
270 | * Iterate backrefs of one extent. |
271 | * |
272 | * Now it only supports iteration of tree block in commit root. |
273 | */ |
274 | struct btrfs_backref_iter { |
275 | u64 bytenr; |
276 | struct btrfs_path *path; |
277 | struct btrfs_fs_info *fs_info; |
278 | struct btrfs_key cur_key; |
279 | u32 item_ptr; |
280 | u32 cur_ptr; |
281 | u32 end_ptr; |
282 | }; |
283 | |
284 | struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info); |
285 | |
286 | /* |
287 | * For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data |
288 | * is btrfs_tree_block_info, without a btrfs_extent_inline_ref header. |
289 | * |
290 | * This helper determines if that's the case. |
291 | */ |
292 | static inline bool btrfs_backref_has_tree_block_info( |
293 | struct btrfs_backref_iter *iter) |
294 | { |
295 | if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY && |
296 | iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item)) |
297 | return true; |
298 | return false; |
299 | } |
300 | |
301 | int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr); |
302 | |
303 | int btrfs_backref_iter_next(struct btrfs_backref_iter *iter); |
304 | |
305 | /* |
306 | * Backref cache related structures |
307 | * |
308 | * The whole objective of backref_cache is to build a bi-directional map |
309 | * of tree blocks (represented by backref_node) and all their parents. |
310 | */ |
311 | |
312 | /* |
313 | * Represent a tree block in the backref cache |
314 | */ |
315 | struct btrfs_backref_node { |
316 | struct { |
317 | struct rb_node rb_node; |
318 | u64 bytenr; |
319 | }; /* Use rb_simple_node for search/insert */ |
320 | |
321 | u64 new_bytenr; |
322 | /* Objectid of tree block owner, can be not uptodate */ |
323 | u64 owner; |
324 | /* Link to pending, changed or detached list */ |
325 | struct list_head list; |
326 | |
327 | /* List of upper level edges, which link this node to its parents */ |
328 | struct list_head upper; |
329 | /* List of lower level edges, which link this node to its children */ |
330 | struct list_head lower; |
331 | |
332 | /* NULL if this node is not tree root */ |
333 | struct btrfs_root *root; |
334 | /* Extent buffer got by COWing the block */ |
335 | struct extent_buffer *eb; |
336 | /* Level of the tree block */ |
337 | unsigned int level:8; |
338 | /* Is the block in a non-shareable tree */ |
339 | unsigned int cowonly:1; |
340 | /* 1 if no child node is in the cache */ |
341 | unsigned int lowest:1; |
342 | /* Is the extent buffer locked */ |
343 | unsigned int locked:1; |
344 | /* Has the block been processed */ |
345 | unsigned int processed:1; |
346 | /* Have backrefs of this block been checked */ |
347 | unsigned int checked:1; |
348 | /* |
349 | * 1 if corresponding block has been COWed but some upper level block |
350 | * pointers may not point to the new location |
351 | */ |
352 | unsigned int pending:1; |
353 | /* 1 if the backref node isn't connected to any other backref node */ |
354 | unsigned int detached:1; |
355 | |
356 | /* |
357 | * For generic purpose backref cache, where we only care if it's a reloc |
358 | * root, doesn't care the source subvolid. |
359 | */ |
360 | unsigned int is_reloc_root:1; |
361 | }; |
362 | |
363 | #define LOWER 0 |
364 | #define UPPER 1 |
365 | |
366 | /* |
367 | * Represent an edge connecting upper and lower backref nodes. |
368 | */ |
369 | struct btrfs_backref_edge { |
370 | /* |
371 | * list[LOWER] is linked to btrfs_backref_node::upper of lower level |
372 | * node, and list[UPPER] is linked to btrfs_backref_node::lower of |
373 | * upper level node. |
374 | * |
375 | * Also, build_backref_tree() uses list[UPPER] for pending edges, before |
376 | * linking list[UPPER] to its upper level nodes. |
377 | */ |
378 | struct list_head list[2]; |
379 | |
380 | /* Two related nodes */ |
381 | struct btrfs_backref_node *node[2]; |
382 | }; |
383 | |
384 | struct btrfs_backref_cache { |
385 | /* Red black tree of all backref nodes in the cache */ |
386 | struct rb_root rb_root; |
387 | /* For passing backref nodes to btrfs_reloc_cow_block */ |
388 | struct btrfs_backref_node *path[BTRFS_MAX_LEVEL]; |
389 | /* |
390 | * List of blocks that have been COWed but some block pointers in upper |
391 | * level blocks may not reflect the new location |
392 | */ |
393 | struct list_head pending[BTRFS_MAX_LEVEL]; |
394 | /* List of backref nodes with no child node */ |
395 | struct list_head leaves; |
396 | /* List of blocks that have been COWed in current transaction */ |
397 | struct list_head changed; |
398 | /* List of detached backref node. */ |
399 | struct list_head detached; |
400 | |
401 | u64 last_trans; |
402 | |
403 | int nr_nodes; |
404 | int nr_edges; |
405 | |
406 | /* List of unchecked backref edges during backref cache build */ |
407 | struct list_head pending_edge; |
408 | |
409 | /* List of useless backref nodes during backref cache build */ |
410 | struct list_head useless_node; |
411 | |
412 | struct btrfs_fs_info *fs_info; |
413 | |
414 | /* |
415 | * Whether this cache is for relocation |
416 | * |
417 | * Reloction backref cache require more info for reloc root compared |
418 | * to generic backref cache. |
419 | */ |
420 | bool is_reloc; |
421 | }; |
422 | |
423 | void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info, |
424 | struct btrfs_backref_cache *cache, bool is_reloc); |
425 | struct btrfs_backref_node *btrfs_backref_alloc_node( |
426 | struct btrfs_backref_cache *cache, u64 bytenr, int level); |
427 | struct btrfs_backref_edge *btrfs_backref_alloc_edge( |
428 | struct btrfs_backref_cache *cache); |
429 | |
430 | #define LINK_LOWER (1 << 0) |
431 | #define LINK_UPPER (1 << 1) |
432 | |
433 | void btrfs_backref_link_edge(struct btrfs_backref_edge *edge, |
434 | struct btrfs_backref_node *lower, |
435 | struct btrfs_backref_node *upper, |
436 | int link_which); |
437 | void btrfs_backref_free_node(struct btrfs_backref_cache *cache, |
438 | struct btrfs_backref_node *node); |
439 | void btrfs_backref_free_edge(struct btrfs_backref_cache *cache, |
440 | struct btrfs_backref_edge *edge); |
441 | void btrfs_backref_unlock_node_buffer(struct btrfs_backref_node *node); |
442 | void btrfs_backref_drop_node_buffer(struct btrfs_backref_node *node); |
443 | |
444 | void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache, |
445 | struct btrfs_backref_node *node); |
446 | void btrfs_backref_drop_node(struct btrfs_backref_cache *tree, |
447 | struct btrfs_backref_node *node); |
448 | |
449 | void btrfs_backref_release_cache(struct btrfs_backref_cache *cache); |
450 | |
451 | static inline void btrfs_backref_panic(struct btrfs_fs_info *fs_info, |
452 | u64 bytenr, int error) |
453 | { |
454 | btrfs_panic(fs_info, error, |
455 | "Inconsistency in backref cache found at offset %llu" , |
456 | bytenr); |
457 | } |
458 | |
459 | int btrfs_backref_add_tree_node(struct btrfs_trans_handle *trans, |
460 | struct btrfs_backref_cache *cache, |
461 | struct btrfs_path *path, |
462 | struct btrfs_backref_iter *iter, |
463 | struct btrfs_key *node_key, |
464 | struct btrfs_backref_node *cur); |
465 | |
466 | int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache, |
467 | struct btrfs_backref_node *start); |
468 | |
469 | void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache, |
470 | struct btrfs_backref_node *node); |
471 | |
472 | #endif |
473 | |