Line data Source code
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/btrfs.h>
10 : #include "messages.h"
11 : #include "ulist.h"
12 : #include "disk-io.h"
13 : #include "extent_io.h"
14 :
15 : /*
16 : * Used by implementations of iterate_extent_inodes_t (see definition below) to
17 : * signal that backref iteration can stop immediately and no error happened.
18 : * The value must be non-negative and must not be 0, 1 (which is a common return
19 : * value from things like btrfs_search_slot() and used internally in the backref
20 : * walking code) and different from BACKREF_FOUND_SHARED and
21 : * BACKREF_FOUND_NOT_SHARED
22 : */
23 : #define BTRFS_ITERATE_EXTENT_INODES_STOP 5
24 :
25 : /*
26 : * Should return 0 if no errors happened and iteration of backrefs should
27 : * continue. Can return BTRFS_ITERATE_EXTENT_INODES_STOP or any other non-zero
28 : * value to immediately stop iteration and possibly signal an error back to
29 : * the caller.
30 : */
31 : typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 num_bytes,
32 : u64 root, void *ctx);
33 :
34 : /*
35 : * Context and arguments for backref walking functions. Some of the fields are
36 : * to be filled by the caller of such functions while other are filled by the
37 : * functions themselves, as described below.
38 : */
39 : struct btrfs_backref_walk_ctx {
40 : /*
41 : * The address of the extent for which we are doing backref walking.
42 : * Can be either a data extent or a metadata extent.
43 : *
44 : * Must always be set by the top level caller.
45 : */
46 : u64 bytenr;
47 : /*
48 : * Offset relative to the target extent. This is only used for data
49 : * extents, and it's meaningful because we can have file extent items
50 : * that point only to a section of a data extent ("bookend" extents),
51 : * and we want to filter out any that don't point to a section of the
52 : * data extent containing the given offset.
53 : *
54 : * Must always be set by the top level caller.
55 : */
56 : u64 extent_item_pos;
57 : /*
58 : * If true and bytenr corresponds to a data extent, then references from
59 : * all file extent items that point to the data extent are considered,
60 : * @extent_item_pos is ignored.
61 : */
62 : bool ignore_extent_item_pos;
63 : /*
64 : * If true and bytenr corresponds to a data extent, then the inode list
65 : * (each member describing inode number, file offset and root) is not
66 : * added to each reference added to the @refs ulist.
67 : */
68 : bool skip_inode_ref_list;
69 : /* A valid transaction handle or NULL. */
70 : struct btrfs_trans_handle *trans;
71 : /*
72 : * The file system's info object, can not be NULL.
73 : *
74 : * Must always be set by the top level caller.
75 : */
76 : struct btrfs_fs_info *fs_info;
77 : /*
78 : * Time sequence acquired from btrfs_get_tree_mod_seq(), in case the
79 : * caller joined the tree mod log to get a consistent view of b+trees
80 : * while we do backref walking, or BTRFS_SEQ_LAST.
81 : * When using BTRFS_SEQ_LAST, delayed refs are not checked and it uses
82 : * commit roots when searching b+trees - this is a special case for
83 : * qgroups used during a transaction commit.
84 : */
85 : u64 time_seq;
86 : /*
87 : * Used to collect the bytenr of metadata extents that point to the
88 : * target extent.
89 : */
90 : struct ulist *refs;
91 : /*
92 : * List used to collect the IDs of the roots from which the target
93 : * extent is accessible. Can be NULL in case the caller does not care
94 : * about collecting root IDs.
95 : */
96 : struct ulist *roots;
97 : /*
98 : * Used by iterate_extent_inodes() and the main backref walk code
99 : * (find_parent_nodes()). Lookup and store functions for an optional
100 : * cache which maps the logical address (bytenr) of leaves to an array
101 : * of root IDs.
102 : */
103 : bool (*cache_lookup)(u64 leaf_bytenr, void *user_ctx,
104 : const u64 **root_ids_ret, int *root_count_ret);
105 : void (*cache_store)(u64 leaf_bytenr, const struct ulist *root_ids,
106 : void *user_ctx);
107 : /*
108 : * If this is not NULL, then the backref walking code will call this
109 : * for each indirect data extent reference as soon as it finds one,
110 : * before collecting all the remaining backrefs and before resolving
111 : * indirect backrefs. This allows for the caller to terminate backref
112 : * walking as soon as it finds one backref that matches some specific
113 : * criteria. The @cache_lookup and @cache_store callbacks should not
114 : * be NULL in order to use this callback.
115 : */
116 : iterate_extent_inodes_t *indirect_ref_iterator;
117 : /*
118 : * If this is not NULL, then the backref walking code will call this for
119 : * each extent item it's meant to process before it actually starts
120 : * processing it. If this returns anything other than 0, then it stops
121 : * the backref walking code immediately.
122 : */
123 : int (*check_extent_item)(u64 bytenr, const struct btrfs_extent_item *ei,
124 : const struct extent_buffer *leaf, void *user_ctx);
125 : /*
126 : * If this is not NULL, then the backref walking code will call this for
127 : * each extent data ref it finds (BTRFS_EXTENT_DATA_REF_KEY keys) before
128 : * processing that data ref. If this callback return false, then it will
129 : * ignore this data ref and it will never resolve the indirect data ref,
130 : * saving time searching for leaves in a fs tree with file extent items
131 : * matching the data ref.
132 : */
133 : bool (*skip_data_ref)(u64 root, u64 ino, u64 offset, void *user_ctx);
134 : /* Context object to pass to the callbacks defined above. */
135 : void *user_ctx;
136 : };
137 :
138 : struct inode_fs_paths {
139 : struct btrfs_path *btrfs_path;
140 : struct btrfs_root *fs_root;
141 : struct btrfs_data_container *fspath;
142 : };
143 :
144 : struct btrfs_backref_shared_cache_entry {
145 : u64 bytenr;
146 : u64 gen;
147 : bool is_shared;
148 : };
149 :
150 : #define BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE 8
151 :
152 : struct btrfs_backref_share_check_ctx {
153 : /* Ulists used during backref walking. */
154 : struct ulist refs;
155 : /*
156 : * The current leaf the caller of btrfs_is_data_extent_shared() is at.
157 : * Typically the caller (at the moment only fiemap) tries to determine
158 : * the sharedness of data extents point by file extent items from entire
159 : * leaves.
160 : */
161 : u64 curr_leaf_bytenr;
162 : /*
163 : * The previous leaf the caller was at in the previous call to
164 : * btrfs_is_data_extent_shared(). This may be the same as the current
165 : * leaf. On the first call it must be 0.
166 : */
167 : u64 prev_leaf_bytenr;
168 : /*
169 : * A path from a root to a leaf that has a file extent item pointing to
170 : * a given data extent should never exceed the maximum b+tree height.
171 : */
172 : struct btrfs_backref_shared_cache_entry path_cache_entries[BTRFS_MAX_LEVEL];
173 : bool use_path_cache;
174 : /*
175 : * Cache the sharedness result for the last few extents we have found,
176 : * but only for extents for which we have multiple file extent items
177 : * that point to them.
178 : * It's very common to have several file extent items that point to the
179 : * same extent (bytenr) but with different offsets and lengths. This
180 : * typically happens for COW writes, partial writes into prealloc
181 : * extents, NOCOW writes after snapshoting a root, hole punching or
182 : * reflinking within the same file (less common perhaps).
183 : * So keep a small cache with the lookup results for the extent pointed
184 : * by the last few file extent items. This cache is checked, with a
185 : * linear scan, whenever btrfs_is_data_extent_shared() is called, so
186 : * it must be small so that it does not negatively affect performance in
187 : * case we don't have multiple file extent items that point to the same
188 : * data extent.
189 : */
190 : struct {
191 : u64 bytenr;
192 : bool is_shared;
193 : } prev_extents_cache[BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE];
194 : /*
195 : * The slot in the prev_extents_cache array that will be used for
196 : * storing the sharedness result of a new data extent.
197 : */
198 : int prev_extents_cache_slot;
199 : };
200 :
201 : struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void);
202 : void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx);
203 :
204 : int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
205 : struct btrfs_path *path, struct btrfs_key *found_key,
206 : u64 *flags);
207 :
208 : int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
209 : struct btrfs_key *key, struct btrfs_extent_item *ei,
210 : u32 item_size, u64 *out_root, u8 *out_level);
211 :
212 : int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx,
213 : bool search_commit_root,
214 : iterate_extent_inodes_t *iterate, void *user_ctx);
215 :
216 : int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
217 : struct btrfs_path *path, void *ctx,
218 : bool ignore_offset);
219 :
220 : int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);
221 :
222 : int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx);
223 : int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx,
224 : bool skip_commit_root_sem);
225 : char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
226 : u32 name_len, unsigned long name_off,
227 : struct extent_buffer *eb_in, u64 parent,
228 : char *dest, u32 size);
229 :
230 : struct btrfs_data_container *init_data_container(u32 total_bytes);
231 : struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
232 : struct btrfs_path *path);
233 : void free_ipath(struct inode_fs_paths *ipath);
234 :
235 : int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
236 : u64 start_off, struct btrfs_path *path,
237 : struct btrfs_inode_extref **ret_extref,
238 : u64 *found_off);
239 : int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,
240 : u64 extent_gen,
241 : struct btrfs_backref_share_check_ctx *ctx);
242 :
243 : int __init btrfs_prelim_ref_init(void);
244 : void __cold btrfs_prelim_ref_exit(void);
245 :
246 : struct prelim_ref {
247 : struct rb_node rbnode;
248 : u64 root_id;
249 : struct btrfs_key key_for_search;
250 : int level;
251 : int count;
252 : struct extent_inode_elem *inode_list;
253 : u64 parent;
254 : u64 wanted_disk_byte;
255 : };
256 :
257 : /*
258 : * Iterate backrefs of one extent.
259 : *
260 : * Now it only supports iteration of tree block in commit root.
261 : */
262 : struct btrfs_backref_iter {
263 : u64 bytenr;
264 : struct btrfs_path *path;
265 : struct btrfs_fs_info *fs_info;
266 : struct btrfs_key cur_key;
267 : u32 item_ptr;
268 : u32 cur_ptr;
269 : u32 end_ptr;
270 : };
271 :
272 : struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info);
273 :
274 0 : static inline void btrfs_backref_iter_free(struct btrfs_backref_iter *iter)
275 : {
276 0 : if (!iter)
277 : return;
278 0 : btrfs_free_path(iter->path);
279 0 : kfree(iter);
280 : }
281 :
282 : static inline struct extent_buffer *btrfs_backref_get_eb(
283 : struct btrfs_backref_iter *iter)
284 : {
285 0 : if (!iter)
286 : return NULL;
287 0 : return iter->path->nodes[0];
288 : }
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 0 : if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY &&
300 0 : iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item))
301 0 : 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 : static inline bool btrfs_backref_iter_is_inline_ref(
310 : struct btrfs_backref_iter *iter)
311 : {
312 0 : if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY ||
313 : iter->cur_key.type == BTRFS_METADATA_ITEM_KEY)
314 0 : return true;
315 : return false;
316 : }
317 :
318 0 : static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
319 : {
320 0 : iter->bytenr = 0;
321 0 : iter->item_ptr = 0;
322 0 : iter->cur_ptr = 0;
323 0 : iter->end_ptr = 0;
324 0 : btrfs_release_path(iter->path);
325 0 : memset(&iter->cur_key, 0, sizeof(iter->cur_key));
326 0 : }
327 :
328 : /*
329 : * Backref cache related structures
330 : *
331 : * The whole objective of backref_cache is to build a bi-directional map
332 : * of tree blocks (represented by backref_node) and all their parents.
333 : */
334 :
335 : /*
336 : * Represent a tree block in the backref cache
337 : */
338 : struct btrfs_backref_node {
339 : struct {
340 : struct rb_node rb_node;
341 : u64 bytenr;
342 : }; /* Use rb_simple_node for search/insert */
343 :
344 : u64 new_bytenr;
345 : /* Objectid of tree block owner, can be not uptodate */
346 : u64 owner;
347 : /* Link to pending, changed or detached list */
348 : struct list_head list;
349 :
350 : /* List of upper level edges, which link this node to its parents */
351 : struct list_head upper;
352 : /* List of lower level edges, which link this node to its children */
353 : struct list_head lower;
354 :
355 : /* NULL if this node is not tree root */
356 : struct btrfs_root *root;
357 : /* Extent buffer got by COWing the block */
358 : struct extent_buffer *eb;
359 : /* Level of the tree block */
360 : unsigned int level:8;
361 : /* Is the block in a non-shareable tree */
362 : unsigned int cowonly:1;
363 : /* 1 if no child node is in the cache */
364 : unsigned int lowest:1;
365 : /* Is the extent buffer locked */
366 : unsigned int locked:1;
367 : /* Has the block been processed */
368 : unsigned int processed:1;
369 : /* Have backrefs of this block been checked */
370 : unsigned int checked:1;
371 : /*
372 : * 1 if corresponding block has been COWed but some upper level block
373 : * pointers may not point to the new location
374 : */
375 : unsigned int pending:1;
376 : /* 1 if the backref node isn't connected to any other backref node */
377 : unsigned int detached:1;
378 :
379 : /*
380 : * For generic purpose backref cache, where we only care if it's a reloc
381 : * root, doesn't care the source subvolid.
382 : */
383 : unsigned int is_reloc_root:1;
384 : };
385 :
386 : #define LOWER 0
387 : #define UPPER 1
388 :
389 : /*
390 : * Represent an edge connecting upper and lower backref nodes.
391 : */
392 : struct btrfs_backref_edge {
393 : /*
394 : * list[LOWER] is linked to btrfs_backref_node::upper of lower level
395 : * node, and list[UPPER] is linked to btrfs_backref_node::lower of
396 : * upper level node.
397 : *
398 : * Also, build_backref_tree() uses list[UPPER] for pending edges, before
399 : * linking list[UPPER] to its upper level nodes.
400 : */
401 : struct list_head list[2];
402 :
403 : /* Two related nodes */
404 : struct btrfs_backref_node *node[2];
405 : };
406 :
407 : struct btrfs_backref_cache {
408 : /* Red black tree of all backref nodes in the cache */
409 : struct rb_root rb_root;
410 : /* For passing backref nodes to btrfs_reloc_cow_block */
411 : struct btrfs_backref_node *path[BTRFS_MAX_LEVEL];
412 : /*
413 : * List of blocks that have been COWed but some block pointers in upper
414 : * level blocks may not reflect the new location
415 : */
416 : struct list_head pending[BTRFS_MAX_LEVEL];
417 : /* List of backref nodes with no child node */
418 : struct list_head leaves;
419 : /* List of blocks that have been COWed in current transaction */
420 : struct list_head changed;
421 : /* List of detached backref node. */
422 : struct list_head detached;
423 :
424 : u64 last_trans;
425 :
426 : int nr_nodes;
427 : int nr_edges;
428 :
429 : /* List of unchecked backref edges during backref cache build */
430 : struct list_head pending_edge;
431 :
432 : /* List of useless backref nodes during backref cache build */
433 : struct list_head useless_node;
434 :
435 : struct btrfs_fs_info *fs_info;
436 :
437 : /*
438 : * Whether this cache is for relocation
439 : *
440 : * Reloction backref cache require more info for reloc root compared
441 : * to generic backref cache.
442 : */
443 : unsigned int is_reloc;
444 : };
445 :
446 : void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
447 : struct btrfs_backref_cache *cache, int is_reloc);
448 : struct btrfs_backref_node *btrfs_backref_alloc_node(
449 : struct btrfs_backref_cache *cache, u64 bytenr, int level);
450 : struct btrfs_backref_edge *btrfs_backref_alloc_edge(
451 : struct btrfs_backref_cache *cache);
452 :
453 : #define LINK_LOWER (1 << 0)
454 : #define LINK_UPPER (1 << 1)
455 : static inline void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
456 : struct btrfs_backref_node *lower,
457 : struct btrfs_backref_node *upper,
458 : int link_which)
459 : {
460 0 : ASSERT(upper && lower && upper->level == lower->level + 1);
461 0 : edge->node[LOWER] = lower;
462 0 : edge->node[UPPER] = upper;
463 0 : if (link_which & LINK_LOWER)
464 0 : list_add_tail(&edge->list[LOWER], &lower->upper);
465 0 : if (link_which & LINK_UPPER)
466 0 : list_add_tail(&edge->list[UPPER], &upper->lower);
467 : }
468 :
469 0 : static inline void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
470 : struct btrfs_backref_node *node)
471 : {
472 0 : if (node) {
473 0 : ASSERT(list_empty(&node->list));
474 0 : ASSERT(list_empty(&node->lower));
475 0 : ASSERT(node->eb == NULL);
476 0 : cache->nr_nodes--;
477 0 : btrfs_put_root(node->root);
478 0 : kfree(node);
479 : }
480 0 : }
481 :
482 : static inline void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
483 : struct btrfs_backref_edge *edge)
484 : {
485 0 : if (edge) {
486 0 : cache->nr_edges--;
487 0 : kfree(edge);
488 : }
489 : }
490 :
491 0 : static inline void btrfs_backref_unlock_node_buffer(
492 : struct btrfs_backref_node *node)
493 : {
494 0 : if (node->locked) {
495 0 : btrfs_tree_unlock(node->eb);
496 0 : node->locked = 0;
497 : }
498 0 : }
499 :
500 0 : static inline void btrfs_backref_drop_node_buffer(
501 : struct btrfs_backref_node *node)
502 : {
503 0 : if (node->eb) {
504 0 : btrfs_backref_unlock_node_buffer(node);
505 0 : free_extent_buffer(node->eb);
506 0 : node->eb = NULL;
507 : }
508 0 : }
509 :
510 : /*
511 : * Drop the backref node from cache without cleaning up its children
512 : * edges.
513 : *
514 : * This can only be called on node without parent edges.
515 : * The children edges are still kept as is.
516 : */
517 0 : static inline void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
518 : struct btrfs_backref_node *node)
519 : {
520 0 : ASSERT(list_empty(&node->upper));
521 :
522 0 : btrfs_backref_drop_node_buffer(node);
523 0 : list_del_init(&node->list);
524 0 : list_del_init(&node->lower);
525 0 : if (!RB_EMPTY_NODE(&node->rb_node))
526 0 : rb_erase(&node->rb_node, &tree->rb_root);
527 0 : btrfs_backref_free_node(tree, node);
528 0 : }
529 :
530 : void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
531 : struct btrfs_backref_node *node);
532 :
533 : void btrfs_backref_release_cache(struct btrfs_backref_cache *cache);
534 :
535 0 : static inline void btrfs_backref_panic(struct btrfs_fs_info *fs_info,
536 : u64 bytenr, int errno)
537 : {
538 0 : btrfs_panic(fs_info, errno,
539 : "Inconsistency in backref cache found at offset %llu",
540 : bytenr);
541 : }
542 :
543 : int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
544 : struct btrfs_path *path,
545 : struct btrfs_backref_iter *iter,
546 : struct btrfs_key *node_key,
547 : struct btrfs_backref_node *cur);
548 :
549 : int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
550 : struct btrfs_backref_node *start);
551 :
552 : void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
553 : struct btrfs_backref_node *node);
554 :
555 : #endif
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