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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 */
31typedef 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 */
39struct 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
138struct inode_fs_paths {
139 struct btrfs_path *btrfs_path;
140 struct btrfs_root *fs_root;
141 struct btrfs_data_container *fspath;
142};
143
144struct 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
152struct 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
201struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void);
202void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx);
203
204int 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
208int 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
212int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx,
213 bool search_commit_root,
214 iterate_extent_inodes_t *iterate, void *user_ctx);
215
216int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
217 struct btrfs_path *path, void *ctx,
218 bool ignore_offset);
219
220int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);
221
222int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx);
223int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx,
224 bool skip_commit_root_sem);
225char *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
230struct btrfs_data_container *init_data_container(u32 total_bytes);
231struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
232 struct btrfs_path *path);
233void free_ipath(struct inode_fs_paths *ipath);
234
235int 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);
239int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,
240 u64 extent_gen,
241 struct btrfs_backref_share_check_ctx *ctx);
242
243int __init btrfs_prelim_ref_init(void);
244void __cold btrfs_prelim_ref_exit(void);
245
246struct prelim_ref {
247 struct rb_node rbnode;
248 u64 root_id;
249 struct btrfs_key key_for_search;
250 u8 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 */
262struct 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
272struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info);
273
274static inline void btrfs_backref_iter_free(struct btrfs_backref_iter *iter)
275{
276 if (!iter)
277 return;
278 btrfs_free_path(iter->path);
279 kfree(iter);
280}
281
282static inline struct extent_buffer *btrfs_backref_get_eb(
283 struct btrfs_backref_iter *iter)
284{
285 if (!iter)
286 return NULL;
287 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 */
296static 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
305int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr);
306
307int btrfs_backref_iter_next(struct btrfs_backref_iter *iter);
308
309static inline bool btrfs_backref_iter_is_inline_ref(
310 struct btrfs_backref_iter *iter)
311{
312 if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY ||
313 iter->cur_key.type == BTRFS_METADATA_ITEM_KEY)
314 return true;
315 return false;
316}
317
318static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
319{
320 iter->bytenr = 0;
321 iter->item_ptr = 0;
322 iter->cur_ptr = 0;
323 iter->end_ptr = 0;
324 btrfs_release_path(iter->path);
325 memset(&iter->cur_key, 0, sizeof(iter->cur_key));
326}
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 */
338struct 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 */
392struct 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
407struct 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 bool is_reloc;
444};
445
446void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
447 struct btrfs_backref_cache *cache, bool is_reloc);
448struct btrfs_backref_node *btrfs_backref_alloc_node(
449 struct btrfs_backref_cache *cache, u64 bytenr, int level);
450struct 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)
455static 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 ASSERT(upper && lower && upper->level == lower->level + 1);
461 edge->node[LOWER] = lower;
462 edge->node[UPPER] = upper;
463 if (link_which & LINK_LOWER)
464 list_add_tail(&edge->list[LOWER], &lower->upper);
465 if (link_which & LINK_UPPER)
466 list_add_tail(&edge->list[UPPER], &upper->lower);
467}
468
469static inline void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
470 struct btrfs_backref_node *node)
471{
472 if (node) {
473 ASSERT(list_empty(&node->list));
474 ASSERT(list_empty(&node->lower));
475 ASSERT(node->eb == NULL);
476 cache->nr_nodes--;
477 btrfs_put_root(node->root);
478 kfree(node);
479 }
480}
481
482static inline void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
483 struct btrfs_backref_edge *edge)
484{
485 if (edge) {
486 cache->nr_edges--;
487 kfree(edge);
488 }
489}
490
491static inline void btrfs_backref_unlock_node_buffer(
492 struct btrfs_backref_node *node)
493{
494 if (node->locked) {
495 btrfs_tree_unlock(node->eb);
496 node->locked = 0;
497 }
498}
499
500static inline void btrfs_backref_drop_node_buffer(
501 struct btrfs_backref_node *node)
502{
503 if (node->eb) {
504 btrfs_backref_unlock_node_buffer(node);
505 free_extent_buffer(node->eb);
506 node->eb = NULL;
507 }
508}
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 */
517static inline void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
518 struct btrfs_backref_node *node)
519{
520 ASSERT(list_empty(&node->upper));
521
522 btrfs_backref_drop_node_buffer(node);
523 list_del_init(&node->list);
524 list_del_init(&node->lower);
525 if (!RB_EMPTY_NODE(&node->rb_node))
526 rb_erase(&node->rb_node, &tree->rb_root);
527 btrfs_backref_free_node(tree, node);
528}
529
530void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
531 struct btrfs_backref_node *node);
532
533void btrfs_backref_release_cache(struct btrfs_backref_cache *cache);
534
535static inline void btrfs_backref_panic(struct btrfs_fs_info *fs_info,
536 u64 bytenr, int error)
537{
538 btrfs_panic(fs_info, error,
539 "Inconsistency in backref cache found at offset %llu",
540 bytenr);
541}
542
543int btrfs_backref_add_tree_node(struct btrfs_trans_handle *trans,
544 struct btrfs_backref_cache *cache,
545 struct btrfs_path *path,
546 struct btrfs_backref_iter *iter,
547 struct btrfs_key *node_key,
548 struct btrfs_backref_node *cur);
549
550int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
551 struct btrfs_backref_node *start);
552
553void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
554 struct btrfs_backref_node *node);
555
556#endif
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 "ulist.h"
11#include "extent_io.h"
12
13struct inode_fs_paths {
14 struct btrfs_path *btrfs_path;
15 struct btrfs_root *fs_root;
16 struct btrfs_data_container *fspath;
17};
18
19typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 root,
20 void *ctx);
21
22int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
23 struct btrfs_path *path, struct btrfs_key *found_key,
24 u64 *flags);
25
26int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
27 struct btrfs_key *key, struct btrfs_extent_item *ei,
28 u32 item_size, u64 *out_root, u8 *out_level);
29
30int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
31 u64 extent_item_objectid,
32 u64 extent_offset, int search_commit_root,
33 iterate_extent_inodes_t *iterate, void *ctx,
34 bool ignore_offset);
35
36int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
37 struct btrfs_path *path,
38 iterate_extent_inodes_t *iterate, void *ctx,
39 bool ignore_offset);
40
41int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);
42
43int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
44 struct btrfs_fs_info *fs_info, u64 bytenr,
45 u64 time_seq, struct ulist **roots, bool ignore_offset);
46char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
47 u32 name_len, unsigned long name_off,
48 struct extent_buffer *eb_in, u64 parent,
49 char *dest, u32 size);
50
51struct btrfs_data_container *init_data_container(u32 total_bytes);
52struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
53 struct btrfs_path *path);
54void free_ipath(struct inode_fs_paths *ipath);
55
56int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
57 u64 start_off, struct btrfs_path *path,
58 struct btrfs_inode_extref **ret_extref,
59 u64 *found_off);
60int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr);
61
62int __init btrfs_prelim_ref_init(void);
63void __cold btrfs_prelim_ref_exit(void);
64
65struct prelim_ref {
66 struct rb_node rbnode;
67 u64 root_id;
68 struct btrfs_key key_for_search;
69 int level;
70 int count;
71 struct extent_inode_elem *inode_list;
72 u64 parent;
73 u64 wanted_disk_byte;
74};
75
76#endif