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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2011 STRATO. All rights reserved.
4 */
5
6#include <linux/mm.h>
7#include <linux/rbtree.h>
8#include <trace/events/btrfs.h>
9#include "ctree.h"
10#include "disk-io.h"
11#include "backref.h"
12#include "ulist.h"
13#include "transaction.h"
14#include "delayed-ref.h"
15#include "locking.h"
16#include "misc.h"
17#include "tree-mod-log.h"
18#include "fs.h"
19#include "accessors.h"
20#include "extent-tree.h"
21#include "relocation.h"
22#include "tree-checker.h"
23
24/* Just arbitrary numbers so we can be sure one of these happened. */
25#define BACKREF_FOUND_SHARED 6
26#define BACKREF_FOUND_NOT_SHARED 7
27
28struct extent_inode_elem {
29 u64 inum;
30 u64 offset;
31 u64 num_bytes;
32 struct extent_inode_elem *next;
33};
34
35static int check_extent_in_eb(struct btrfs_backref_walk_ctx *ctx,
36 const struct btrfs_key *key,
37 const struct extent_buffer *eb,
38 const struct btrfs_file_extent_item *fi,
39 struct extent_inode_elem **eie)
40{
41 const u64 data_len = btrfs_file_extent_num_bytes(eb, fi);
42 u64 offset = key->offset;
43 struct extent_inode_elem *e;
44 const u64 *root_ids;
45 int root_count;
46 bool cached;
47
48 if (!btrfs_file_extent_compression(eb, fi) &&
49 !btrfs_file_extent_encryption(eb, fi) &&
50 !btrfs_file_extent_other_encoding(eb, fi)) {
51 u64 data_offset;
52
53 data_offset = btrfs_file_extent_offset(eb, fi);
54
55 if (ctx->extent_item_pos < data_offset ||
56 ctx->extent_item_pos >= data_offset + data_len)
57 return 1;
58 offset += ctx->extent_item_pos - data_offset;
59 }
60
61 if (!ctx->indirect_ref_iterator || !ctx->cache_lookup)
62 goto add_inode_elem;
63
64 cached = ctx->cache_lookup(eb->start, ctx->user_ctx, &root_ids,
65 &root_count);
66 if (!cached)
67 goto add_inode_elem;
68
69 for (int i = 0; i < root_count; i++) {
70 int ret;
71
72 ret = ctx->indirect_ref_iterator(key->objectid, offset,
73 data_len, root_ids[i],
74 ctx->user_ctx);
75 if (ret)
76 return ret;
77 }
78
79add_inode_elem:
80 e = kmalloc(sizeof(*e), GFP_NOFS);
81 if (!e)
82 return -ENOMEM;
83
84 e->next = *eie;
85 e->inum = key->objectid;
86 e->offset = offset;
87 e->num_bytes = data_len;
88 *eie = e;
89
90 return 0;
91}
92
93static void free_inode_elem_list(struct extent_inode_elem *eie)
94{
95 struct extent_inode_elem *eie_next;
96
97 for (; eie; eie = eie_next) {
98 eie_next = eie->next;
99 kfree(eie);
100 }
101}
102
103static int find_extent_in_eb(struct btrfs_backref_walk_ctx *ctx,
104 const struct extent_buffer *eb,
105 struct extent_inode_elem **eie)
106{
107 u64 disk_byte;
108 struct btrfs_key key;
109 struct btrfs_file_extent_item *fi;
110 int slot;
111 int nritems;
112 int extent_type;
113 int ret;
114
115 /*
116 * from the shared data ref, we only have the leaf but we need
117 * the key. thus, we must look into all items and see that we
118 * find one (some) with a reference to our extent item.
119 */
120 nritems = btrfs_header_nritems(eb);
121 for (slot = 0; slot < nritems; ++slot) {
122 btrfs_item_key_to_cpu(eb, &key, slot);
123 if (key.type != BTRFS_EXTENT_DATA_KEY)
124 continue;
125 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
126 extent_type = btrfs_file_extent_type(eb, fi);
127 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
128 continue;
129 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
130 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
131 if (disk_byte != ctx->bytenr)
132 continue;
133
134 ret = check_extent_in_eb(ctx, &key, eb, fi, eie);
135 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
136 return ret;
137 }
138
139 return 0;
140}
141
142struct preftree {
143 struct rb_root_cached root;
144 unsigned int count;
145};
146
147#define PREFTREE_INIT { .root = RB_ROOT_CACHED, .count = 0 }
148
149struct preftrees {
150 struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */
151 struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */
152 struct preftree indirect_missing_keys;
153};
154
155/*
156 * Checks for a shared extent during backref search.
157 *
158 * The share_count tracks prelim_refs (direct and indirect) having a
159 * ref->count >0:
160 * - incremented when a ref->count transitions to >0
161 * - decremented when a ref->count transitions to <1
162 */
163struct share_check {
164 struct btrfs_backref_share_check_ctx *ctx;
165 struct btrfs_root *root;
166 u64 inum;
167 u64 data_bytenr;
168 u64 data_extent_gen;
169 /*
170 * Counts number of inodes that refer to an extent (different inodes in
171 * the same root or different roots) that we could find. The sharedness
172 * check typically stops once this counter gets greater than 1, so it
173 * may not reflect the total number of inodes.
174 */
175 int share_count;
176 /*
177 * The number of times we found our inode refers to the data extent we
178 * are determining the sharedness. In other words, how many file extent
179 * items we could find for our inode that point to our target data
180 * extent. The value we get here after finishing the extent sharedness
181 * check may be smaller than reality, but if it ends up being greater
182 * than 1, then we know for sure the inode has multiple file extent
183 * items that point to our inode, and we can safely assume it's useful
184 * to cache the sharedness check result.
185 */
186 int self_ref_count;
187 bool have_delayed_delete_refs;
188};
189
190static inline int extent_is_shared(struct share_check *sc)
191{
192 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
193}
194
195static struct kmem_cache *btrfs_prelim_ref_cache;
196
197int __init btrfs_prelim_ref_init(void)
198{
199 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
200 sizeof(struct prelim_ref),
201 0,
202 SLAB_MEM_SPREAD,
203 NULL);
204 if (!btrfs_prelim_ref_cache)
205 return -ENOMEM;
206 return 0;
207}
208
209void __cold btrfs_prelim_ref_exit(void)
210{
211 kmem_cache_destroy(btrfs_prelim_ref_cache);
212}
213
214static void free_pref(struct prelim_ref *ref)
215{
216 kmem_cache_free(btrfs_prelim_ref_cache, ref);
217}
218
219/*
220 * Return 0 when both refs are for the same block (and can be merged).
221 * A -1 return indicates ref1 is a 'lower' block than ref2, while 1
222 * indicates a 'higher' block.
223 */
224static int prelim_ref_compare(struct prelim_ref *ref1,
225 struct prelim_ref *ref2)
226{
227 if (ref1->level < ref2->level)
228 return -1;
229 if (ref1->level > ref2->level)
230 return 1;
231 if (ref1->root_id < ref2->root_id)
232 return -1;
233 if (ref1->root_id > ref2->root_id)
234 return 1;
235 if (ref1->key_for_search.type < ref2->key_for_search.type)
236 return -1;
237 if (ref1->key_for_search.type > ref2->key_for_search.type)
238 return 1;
239 if (ref1->key_for_search.objectid < ref2->key_for_search.objectid)
240 return -1;
241 if (ref1->key_for_search.objectid > ref2->key_for_search.objectid)
242 return 1;
243 if (ref1->key_for_search.offset < ref2->key_for_search.offset)
244 return -1;
245 if (ref1->key_for_search.offset > ref2->key_for_search.offset)
246 return 1;
247 if (ref1->parent < ref2->parent)
248 return -1;
249 if (ref1->parent > ref2->parent)
250 return 1;
251
252 return 0;
253}
254
255static void update_share_count(struct share_check *sc, int oldcount,
256 int newcount, struct prelim_ref *newref)
257{
258 if ((!sc) || (oldcount == 0 && newcount < 1))
259 return;
260
261 if (oldcount > 0 && newcount < 1)
262 sc->share_count--;
263 else if (oldcount < 1 && newcount > 0)
264 sc->share_count++;
265
266 if (newref->root_id == sc->root->root_key.objectid &&
267 newref->wanted_disk_byte == sc->data_bytenr &&
268 newref->key_for_search.objectid == sc->inum)
269 sc->self_ref_count += newref->count;
270}
271
272/*
273 * Add @newref to the @root rbtree, merging identical refs.
274 *
275 * Callers should assume that newref has been freed after calling.
276 */
277static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
278 struct preftree *preftree,
279 struct prelim_ref *newref,
280 struct share_check *sc)
281{
282 struct rb_root_cached *root;
283 struct rb_node **p;
284 struct rb_node *parent = NULL;
285 struct prelim_ref *ref;
286 int result;
287 bool leftmost = true;
288
289 root = &preftree->root;
290 p = &root->rb_root.rb_node;
291
292 while (*p) {
293 parent = *p;
294 ref = rb_entry(parent, struct prelim_ref, rbnode);
295 result = prelim_ref_compare(ref, newref);
296 if (result < 0) {
297 p = &(*p)->rb_left;
298 } else if (result > 0) {
299 p = &(*p)->rb_right;
300 leftmost = false;
301 } else {
302 /* Identical refs, merge them and free @newref */
303 struct extent_inode_elem *eie = ref->inode_list;
304
305 while (eie && eie->next)
306 eie = eie->next;
307
308 if (!eie)
309 ref->inode_list = newref->inode_list;
310 else
311 eie->next = newref->inode_list;
312 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
313 preftree->count);
314 /*
315 * A delayed ref can have newref->count < 0.
316 * The ref->count is updated to follow any
317 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
318 */
319 update_share_count(sc, ref->count,
320 ref->count + newref->count, newref);
321 ref->count += newref->count;
322 free_pref(newref);
323 return;
324 }
325 }
326
327 update_share_count(sc, 0, newref->count, newref);
328 preftree->count++;
329 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
330 rb_link_node(&newref->rbnode, parent, p);
331 rb_insert_color_cached(&newref->rbnode, root, leftmost);
332}
333
334/*
335 * Release the entire tree. We don't care about internal consistency so
336 * just free everything and then reset the tree root.
337 */
338static void prelim_release(struct preftree *preftree)
339{
340 struct prelim_ref *ref, *next_ref;
341
342 rbtree_postorder_for_each_entry_safe(ref, next_ref,
343 &preftree->root.rb_root, rbnode) {
344 free_inode_elem_list(ref->inode_list);
345 free_pref(ref);
346 }
347
348 preftree->root = RB_ROOT_CACHED;
349 preftree->count = 0;
350}
351
352/*
353 * the rules for all callers of this function are:
354 * - obtaining the parent is the goal
355 * - if you add a key, you must know that it is a correct key
356 * - if you cannot add the parent or a correct key, then we will look into the
357 * block later to set a correct key
358 *
359 * delayed refs
360 * ============
361 * backref type | shared | indirect | shared | indirect
362 * information | tree | tree | data | data
363 * --------------------+--------+----------+--------+----------
364 * parent logical | y | - | - | -
365 * key to resolve | - | y | y | y
366 * tree block logical | - | - | - | -
367 * root for resolving | y | y | y | y
368 *
369 * - column 1: we've the parent -> done
370 * - column 2, 3, 4: we use the key to find the parent
371 *
372 * on disk refs (inline or keyed)
373 * ==============================
374 * backref type | shared | indirect | shared | indirect
375 * information | tree | tree | data | data
376 * --------------------+--------+----------+--------+----------
377 * parent logical | y | - | y | -
378 * key to resolve | - | - | - | y
379 * tree block logical | y | y | y | y
380 * root for resolving | - | y | y | y
381 *
382 * - column 1, 3: we've the parent -> done
383 * - column 2: we take the first key from the block to find the parent
384 * (see add_missing_keys)
385 * - column 4: we use the key to find the parent
386 *
387 * additional information that's available but not required to find the parent
388 * block might help in merging entries to gain some speed.
389 */
390static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
391 struct preftree *preftree, u64 root_id,
392 const struct btrfs_key *key, int level, u64 parent,
393 u64 wanted_disk_byte, int count,
394 struct share_check *sc, gfp_t gfp_mask)
395{
396 struct prelim_ref *ref;
397
398 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
399 return 0;
400
401 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
402 if (!ref)
403 return -ENOMEM;
404
405 ref->root_id = root_id;
406 if (key)
407 ref->key_for_search = *key;
408 else
409 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
410
411 ref->inode_list = NULL;
412 ref->level = level;
413 ref->count = count;
414 ref->parent = parent;
415 ref->wanted_disk_byte = wanted_disk_byte;
416 prelim_ref_insert(fs_info, preftree, ref, sc);
417 return extent_is_shared(sc);
418}
419
420/* direct refs use root == 0, key == NULL */
421static int add_direct_ref(const struct btrfs_fs_info *fs_info,
422 struct preftrees *preftrees, int level, u64 parent,
423 u64 wanted_disk_byte, int count,
424 struct share_check *sc, gfp_t gfp_mask)
425{
426 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
427 parent, wanted_disk_byte, count, sc, gfp_mask);
428}
429
430/* indirect refs use parent == 0 */
431static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
432 struct preftrees *preftrees, u64 root_id,
433 const struct btrfs_key *key, int level,
434 u64 wanted_disk_byte, int count,
435 struct share_check *sc, gfp_t gfp_mask)
436{
437 struct preftree *tree = &preftrees->indirect;
438
439 if (!key)
440 tree = &preftrees->indirect_missing_keys;
441 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
442 wanted_disk_byte, count, sc, gfp_mask);
443}
444
445static int is_shared_data_backref(struct preftrees *preftrees, u64 bytenr)
446{
447 struct rb_node **p = &preftrees->direct.root.rb_root.rb_node;
448 struct rb_node *parent = NULL;
449 struct prelim_ref *ref = NULL;
450 struct prelim_ref target = {};
451 int result;
452
453 target.parent = bytenr;
454
455 while (*p) {
456 parent = *p;
457 ref = rb_entry(parent, struct prelim_ref, rbnode);
458 result = prelim_ref_compare(ref, &target);
459
460 if (result < 0)
461 p = &(*p)->rb_left;
462 else if (result > 0)
463 p = &(*p)->rb_right;
464 else
465 return 1;
466 }
467 return 0;
468}
469
470static int add_all_parents(struct btrfs_backref_walk_ctx *ctx,
471 struct btrfs_root *root, struct btrfs_path *path,
472 struct ulist *parents,
473 struct preftrees *preftrees, struct prelim_ref *ref,
474 int level)
475{
476 int ret = 0;
477 int slot;
478 struct extent_buffer *eb;
479 struct btrfs_key key;
480 struct btrfs_key *key_for_search = &ref->key_for_search;
481 struct btrfs_file_extent_item *fi;
482 struct extent_inode_elem *eie = NULL, *old = NULL;
483 u64 disk_byte;
484 u64 wanted_disk_byte = ref->wanted_disk_byte;
485 u64 count = 0;
486 u64 data_offset;
487 u8 type;
488
489 if (level != 0) {
490 eb = path->nodes[level];
491 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
492 if (ret < 0)
493 return ret;
494 return 0;
495 }
496
497 /*
498 * 1. We normally enter this function with the path already pointing to
499 * the first item to check. But sometimes, we may enter it with
500 * slot == nritems.
501 * 2. We are searching for normal backref but bytenr of this leaf
502 * matches shared data backref
503 * 3. The leaf owner is not equal to the root we are searching
504 *
505 * For these cases, go to the next leaf before we continue.
506 */
507 eb = path->nodes[0];
508 if (path->slots[0] >= btrfs_header_nritems(eb) ||
509 is_shared_data_backref(preftrees, eb->start) ||
510 ref->root_id != btrfs_header_owner(eb)) {
511 if (ctx->time_seq == BTRFS_SEQ_LAST)
512 ret = btrfs_next_leaf(root, path);
513 else
514 ret = btrfs_next_old_leaf(root, path, ctx->time_seq);
515 }
516
517 while (!ret && count < ref->count) {
518 eb = path->nodes[0];
519 slot = path->slots[0];
520
521 btrfs_item_key_to_cpu(eb, &key, slot);
522
523 if (key.objectid != key_for_search->objectid ||
524 key.type != BTRFS_EXTENT_DATA_KEY)
525 break;
526
527 /*
528 * We are searching for normal backref but bytenr of this leaf
529 * matches shared data backref, OR
530 * the leaf owner is not equal to the root we are searching for
531 */
532 if (slot == 0 &&
533 (is_shared_data_backref(preftrees, eb->start) ||
534 ref->root_id != btrfs_header_owner(eb))) {
535 if (ctx->time_seq == BTRFS_SEQ_LAST)
536 ret = btrfs_next_leaf(root, path);
537 else
538 ret = btrfs_next_old_leaf(root, path, ctx->time_seq);
539 continue;
540 }
541 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
542 type = btrfs_file_extent_type(eb, fi);
543 if (type == BTRFS_FILE_EXTENT_INLINE)
544 goto next;
545 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
546 data_offset = btrfs_file_extent_offset(eb, fi);
547
548 if (disk_byte == wanted_disk_byte) {
549 eie = NULL;
550 old = NULL;
551 if (ref->key_for_search.offset == key.offset - data_offset)
552 count++;
553 else
554 goto next;
555 if (!ctx->ignore_extent_item_pos) {
556 ret = check_extent_in_eb(ctx, &key, eb, fi, &eie);
557 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
558 ret < 0)
559 break;
560 }
561 if (ret > 0)
562 goto next;
563 ret = ulist_add_merge_ptr(parents, eb->start,
564 eie, (void **)&old, GFP_NOFS);
565 if (ret < 0)
566 break;
567 if (!ret && !ctx->ignore_extent_item_pos) {
568 while (old->next)
569 old = old->next;
570 old->next = eie;
571 }
572 eie = NULL;
573 }
574next:
575 if (ctx->time_seq == BTRFS_SEQ_LAST)
576 ret = btrfs_next_item(root, path);
577 else
578 ret = btrfs_next_old_item(root, path, ctx->time_seq);
579 }
580
581 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
582 free_inode_elem_list(eie);
583 else if (ret > 0)
584 ret = 0;
585
586 return ret;
587}
588
589/*
590 * resolve an indirect backref in the form (root_id, key, level)
591 * to a logical address
592 */
593static int resolve_indirect_ref(struct btrfs_backref_walk_ctx *ctx,
594 struct btrfs_path *path,
595 struct preftrees *preftrees,
596 struct prelim_ref *ref, struct ulist *parents)
597{
598 struct btrfs_root *root;
599 struct extent_buffer *eb;
600 int ret = 0;
601 int root_level;
602 int level = ref->level;
603 struct btrfs_key search_key = ref->key_for_search;
604
605 /*
606 * If we're search_commit_root we could possibly be holding locks on
607 * other tree nodes. This happens when qgroups does backref walks when
608 * adding new delayed refs. To deal with this we need to look in cache
609 * for the root, and if we don't find it then we need to search the
610 * tree_root's commit root, thus the btrfs_get_fs_root_commit_root usage
611 * here.
612 */
613 if (path->search_commit_root)
614 root = btrfs_get_fs_root_commit_root(ctx->fs_info, path, ref->root_id);
615 else
616 root = btrfs_get_fs_root(ctx->fs_info, ref->root_id, false);
617 if (IS_ERR(root)) {
618 ret = PTR_ERR(root);
619 goto out_free;
620 }
621
622 if (!path->search_commit_root &&
623 test_bit(BTRFS_ROOT_DELETING, &root->state)) {
624 ret = -ENOENT;
625 goto out;
626 }
627
628 if (btrfs_is_testing(ctx->fs_info)) {
629 ret = -ENOENT;
630 goto out;
631 }
632
633 if (path->search_commit_root)
634 root_level = btrfs_header_level(root->commit_root);
635 else if (ctx->time_seq == BTRFS_SEQ_LAST)
636 root_level = btrfs_header_level(root->node);
637 else
638 root_level = btrfs_old_root_level(root, ctx->time_seq);
639
640 if (root_level + 1 == level)
641 goto out;
642
643 /*
644 * We can often find data backrefs with an offset that is too large
645 * (>= LLONG_MAX, maximum allowed file offset) due to underflows when
646 * subtracting a file's offset with the data offset of its
647 * corresponding extent data item. This can happen for example in the
648 * clone ioctl.
649 *
650 * So if we detect such case we set the search key's offset to zero to
651 * make sure we will find the matching file extent item at
652 * add_all_parents(), otherwise we will miss it because the offset
653 * taken form the backref is much larger then the offset of the file
654 * extent item. This can make us scan a very large number of file
655 * extent items, but at least it will not make us miss any.
656 *
657 * This is an ugly workaround for a behaviour that should have never
658 * existed, but it does and a fix for the clone ioctl would touch a lot
659 * of places, cause backwards incompatibility and would not fix the
660 * problem for extents cloned with older kernels.
661 */
662 if (search_key.type == BTRFS_EXTENT_DATA_KEY &&
663 search_key.offset >= LLONG_MAX)
664 search_key.offset = 0;
665 path->lowest_level = level;
666 if (ctx->time_seq == BTRFS_SEQ_LAST)
667 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
668 else
669 ret = btrfs_search_old_slot(root, &search_key, path, ctx->time_seq);
670
671 btrfs_debug(ctx->fs_info,
672 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
673 ref->root_id, level, ref->count, ret,
674 ref->key_for_search.objectid, ref->key_for_search.type,
675 ref->key_for_search.offset);
676 if (ret < 0)
677 goto out;
678
679 eb = path->nodes[level];
680 while (!eb) {
681 if (WARN_ON(!level)) {
682 ret = 1;
683 goto out;
684 }
685 level--;
686 eb = path->nodes[level];
687 }
688
689 ret = add_all_parents(ctx, root, path, parents, preftrees, ref, level);
690out:
691 btrfs_put_root(root);
692out_free:
693 path->lowest_level = 0;
694 btrfs_release_path(path);
695 return ret;
696}
697
698static struct extent_inode_elem *
699unode_aux_to_inode_list(struct ulist_node *node)
700{
701 if (!node)
702 return NULL;
703 return (struct extent_inode_elem *)(uintptr_t)node->aux;
704}
705
706static void free_leaf_list(struct ulist *ulist)
707{
708 struct ulist_node *node;
709 struct ulist_iterator uiter;
710
711 ULIST_ITER_INIT(&uiter);
712 while ((node = ulist_next(ulist, &uiter)))
713 free_inode_elem_list(unode_aux_to_inode_list(node));
714
715 ulist_free(ulist);
716}
717
718/*
719 * We maintain three separate rbtrees: one for direct refs, one for
720 * indirect refs which have a key, and one for indirect refs which do not
721 * have a key. Each tree does merge on insertion.
722 *
723 * Once all of the references are located, we iterate over the tree of
724 * indirect refs with missing keys. An appropriate key is located and
725 * the ref is moved onto the tree for indirect refs. After all missing
726 * keys are thus located, we iterate over the indirect ref tree, resolve
727 * each reference, and then insert the resolved reference onto the
728 * direct tree (merging there too).
729 *
730 * New backrefs (i.e., for parent nodes) are added to the appropriate
731 * rbtree as they are encountered. The new backrefs are subsequently
732 * resolved as above.
733 */
734static int resolve_indirect_refs(struct btrfs_backref_walk_ctx *ctx,
735 struct btrfs_path *path,
736 struct preftrees *preftrees,
737 struct share_check *sc)
738{
739 int err;
740 int ret = 0;
741 struct ulist *parents;
742 struct ulist_node *node;
743 struct ulist_iterator uiter;
744 struct rb_node *rnode;
745
746 parents = ulist_alloc(GFP_NOFS);
747 if (!parents)
748 return -ENOMEM;
749
750 /*
751 * We could trade memory usage for performance here by iterating
752 * the tree, allocating new refs for each insertion, and then
753 * freeing the entire indirect tree when we're done. In some test
754 * cases, the tree can grow quite large (~200k objects).
755 */
756 while ((rnode = rb_first_cached(&preftrees->indirect.root))) {
757 struct prelim_ref *ref;
758
759 ref = rb_entry(rnode, struct prelim_ref, rbnode);
760 if (WARN(ref->parent,
761 "BUG: direct ref found in indirect tree")) {
762 ret = -EINVAL;
763 goto out;
764 }
765
766 rb_erase_cached(&ref->rbnode, &preftrees->indirect.root);
767 preftrees->indirect.count--;
768
769 if (ref->count == 0) {
770 free_pref(ref);
771 continue;
772 }
773
774 if (sc && ref->root_id != sc->root->root_key.objectid) {
775 free_pref(ref);
776 ret = BACKREF_FOUND_SHARED;
777 goto out;
778 }
779 err = resolve_indirect_ref(ctx, path, preftrees, ref, parents);
780 /*
781 * we can only tolerate ENOENT,otherwise,we should catch error
782 * and return directly.
783 */
784 if (err == -ENOENT) {
785 prelim_ref_insert(ctx->fs_info, &preftrees->direct, ref,
786 NULL);
787 continue;
788 } else if (err) {
789 free_pref(ref);
790 ret = err;
791 goto out;
792 }
793
794 /* we put the first parent into the ref at hand */
795 ULIST_ITER_INIT(&uiter);
796 node = ulist_next(parents, &uiter);
797 ref->parent = node ? node->val : 0;
798 ref->inode_list = unode_aux_to_inode_list(node);
799
800 /* Add a prelim_ref(s) for any other parent(s). */
801 while ((node = ulist_next(parents, &uiter))) {
802 struct prelim_ref *new_ref;
803
804 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
805 GFP_NOFS);
806 if (!new_ref) {
807 free_pref(ref);
808 ret = -ENOMEM;
809 goto out;
810 }
811 memcpy(new_ref, ref, sizeof(*ref));
812 new_ref->parent = node->val;
813 new_ref->inode_list = unode_aux_to_inode_list(node);
814 prelim_ref_insert(ctx->fs_info, &preftrees->direct,
815 new_ref, NULL);
816 }
817
818 /*
819 * Now it's a direct ref, put it in the direct tree. We must
820 * do this last because the ref could be merged/freed here.
821 */
822 prelim_ref_insert(ctx->fs_info, &preftrees->direct, ref, NULL);
823
824 ulist_reinit(parents);
825 cond_resched();
826 }
827out:
828 /*
829 * We may have inode lists attached to refs in the parents ulist, so we
830 * must free them before freeing the ulist and its refs.
831 */
832 free_leaf_list(parents);
833 return ret;
834}
835
836/*
837 * read tree blocks and add keys where required.
838 */
839static int add_missing_keys(struct btrfs_fs_info *fs_info,
840 struct preftrees *preftrees, bool lock)
841{
842 struct prelim_ref *ref;
843 struct extent_buffer *eb;
844 struct preftree *tree = &preftrees->indirect_missing_keys;
845 struct rb_node *node;
846
847 while ((node = rb_first_cached(&tree->root))) {
848 struct btrfs_tree_parent_check check = { 0 };
849
850 ref = rb_entry(node, struct prelim_ref, rbnode);
851 rb_erase_cached(node, &tree->root);
852
853 BUG_ON(ref->parent); /* should not be a direct ref */
854 BUG_ON(ref->key_for_search.type);
855 BUG_ON(!ref->wanted_disk_byte);
856
857 check.level = ref->level - 1;
858 check.owner_root = ref->root_id;
859
860 eb = read_tree_block(fs_info, ref->wanted_disk_byte, &check);
861 if (IS_ERR(eb)) {
862 free_pref(ref);
863 return PTR_ERR(eb);
864 }
865 if (!extent_buffer_uptodate(eb)) {
866 free_pref(ref);
867 free_extent_buffer(eb);
868 return -EIO;
869 }
870
871 if (lock)
872 btrfs_tree_read_lock(eb);
873 if (btrfs_header_level(eb) == 0)
874 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
875 else
876 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
877 if (lock)
878 btrfs_tree_read_unlock(eb);
879 free_extent_buffer(eb);
880 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
881 cond_resched();
882 }
883 return 0;
884}
885
886/*
887 * add all currently queued delayed refs from this head whose seq nr is
888 * smaller or equal that seq to the list
889 */
890static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
891 struct btrfs_delayed_ref_head *head, u64 seq,
892 struct preftrees *preftrees, struct share_check *sc)
893{
894 struct btrfs_delayed_ref_node *node;
895 struct btrfs_key key;
896 struct rb_node *n;
897 int count;
898 int ret = 0;
899
900 spin_lock(&head->lock);
901 for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
902 node = rb_entry(n, struct btrfs_delayed_ref_node,
903 ref_node);
904 if (node->seq > seq)
905 continue;
906
907 switch (node->action) {
908 case BTRFS_ADD_DELAYED_EXTENT:
909 case BTRFS_UPDATE_DELAYED_HEAD:
910 WARN_ON(1);
911 continue;
912 case BTRFS_ADD_DELAYED_REF:
913 count = node->ref_mod;
914 break;
915 case BTRFS_DROP_DELAYED_REF:
916 count = node->ref_mod * -1;
917 break;
918 default:
919 BUG();
920 }
921 switch (node->type) {
922 case BTRFS_TREE_BLOCK_REF_KEY: {
923 /* NORMAL INDIRECT METADATA backref */
924 struct btrfs_delayed_tree_ref *ref;
925 struct btrfs_key *key_ptr = NULL;
926
927 if (head->extent_op && head->extent_op->update_key) {
928 btrfs_disk_key_to_cpu(&key, &head->extent_op->key);
929 key_ptr = &key;
930 }
931
932 ref = btrfs_delayed_node_to_tree_ref(node);
933 ret = add_indirect_ref(fs_info, preftrees, ref->root,
934 key_ptr, ref->level + 1,
935 node->bytenr, count, sc,
936 GFP_ATOMIC);
937 break;
938 }
939 case BTRFS_SHARED_BLOCK_REF_KEY: {
940 /* SHARED DIRECT METADATA backref */
941 struct btrfs_delayed_tree_ref *ref;
942
943 ref = btrfs_delayed_node_to_tree_ref(node);
944
945 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
946 ref->parent, node->bytenr, count,
947 sc, GFP_ATOMIC);
948 break;
949 }
950 case BTRFS_EXTENT_DATA_REF_KEY: {
951 /* NORMAL INDIRECT DATA backref */
952 struct btrfs_delayed_data_ref *ref;
953 ref = btrfs_delayed_node_to_data_ref(node);
954
955 key.objectid = ref->objectid;
956 key.type = BTRFS_EXTENT_DATA_KEY;
957 key.offset = ref->offset;
958
959 /*
960 * If we have a share check context and a reference for
961 * another inode, we can't exit immediately. This is
962 * because even if this is a BTRFS_ADD_DELAYED_REF
963 * reference we may find next a BTRFS_DROP_DELAYED_REF
964 * which cancels out this ADD reference.
965 *
966 * If this is a DROP reference and there was no previous
967 * ADD reference, then we need to signal that when we
968 * process references from the extent tree (through
969 * add_inline_refs() and add_keyed_refs()), we should
970 * not exit early if we find a reference for another
971 * inode, because one of the delayed DROP references
972 * may cancel that reference in the extent tree.
973 */
974 if (sc && count < 0)
975 sc->have_delayed_delete_refs = true;
976
977 ret = add_indirect_ref(fs_info, preftrees, ref->root,
978 &key, 0, node->bytenr, count, sc,
979 GFP_ATOMIC);
980 break;
981 }
982 case BTRFS_SHARED_DATA_REF_KEY: {
983 /* SHARED DIRECT FULL backref */
984 struct btrfs_delayed_data_ref *ref;
985
986 ref = btrfs_delayed_node_to_data_ref(node);
987
988 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
989 node->bytenr, count, sc,
990 GFP_ATOMIC);
991 break;
992 }
993 default:
994 WARN_ON(1);
995 }
996 /*
997 * We must ignore BACKREF_FOUND_SHARED until all delayed
998 * refs have been checked.
999 */
1000 if (ret && (ret != BACKREF_FOUND_SHARED))
1001 break;
1002 }
1003 if (!ret)
1004 ret = extent_is_shared(sc);
1005
1006 spin_unlock(&head->lock);
1007 return ret;
1008}
1009
1010/*
1011 * add all inline backrefs for bytenr to the list
1012 *
1013 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
1014 */
1015static int add_inline_refs(struct btrfs_backref_walk_ctx *ctx,
1016 struct btrfs_path *path,
1017 int *info_level, struct preftrees *preftrees,
1018 struct share_check *sc)
1019{
1020 int ret = 0;
1021 int slot;
1022 struct extent_buffer *leaf;
1023 struct btrfs_key key;
1024 struct btrfs_key found_key;
1025 unsigned long ptr;
1026 unsigned long end;
1027 struct btrfs_extent_item *ei;
1028 u64 flags;
1029 u64 item_size;
1030
1031 /*
1032 * enumerate all inline refs
1033 */
1034 leaf = path->nodes[0];
1035 slot = path->slots[0];
1036
1037 item_size = btrfs_item_size(leaf, slot);
1038 BUG_ON(item_size < sizeof(*ei));
1039
1040 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
1041
1042 if (ctx->check_extent_item) {
1043 ret = ctx->check_extent_item(ctx->bytenr, ei, leaf, ctx->user_ctx);
1044 if (ret)
1045 return ret;
1046 }
1047
1048 flags = btrfs_extent_flags(leaf, ei);
1049 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1050
1051 ptr = (unsigned long)(ei + 1);
1052 end = (unsigned long)ei + item_size;
1053
1054 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
1055 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1056 struct btrfs_tree_block_info *info;
1057
1058 info = (struct btrfs_tree_block_info *)ptr;
1059 *info_level = btrfs_tree_block_level(leaf, info);
1060 ptr += sizeof(struct btrfs_tree_block_info);
1061 BUG_ON(ptr > end);
1062 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
1063 *info_level = found_key.offset;
1064 } else {
1065 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
1066 }
1067
1068 while (ptr < end) {
1069 struct btrfs_extent_inline_ref *iref;
1070 u64 offset;
1071 int type;
1072
1073 iref = (struct btrfs_extent_inline_ref *)ptr;
1074 type = btrfs_get_extent_inline_ref_type(leaf, iref,
1075 BTRFS_REF_TYPE_ANY);
1076 if (type == BTRFS_REF_TYPE_INVALID)
1077 return -EUCLEAN;
1078
1079 offset = btrfs_extent_inline_ref_offset(leaf, iref);
1080
1081 switch (type) {
1082 case BTRFS_SHARED_BLOCK_REF_KEY:
1083 ret = add_direct_ref(ctx->fs_info, preftrees,
1084 *info_level + 1, offset,
1085 ctx->bytenr, 1, NULL, GFP_NOFS);
1086 break;
1087 case BTRFS_SHARED_DATA_REF_KEY: {
1088 struct btrfs_shared_data_ref *sdref;
1089 int count;
1090
1091 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
1092 count = btrfs_shared_data_ref_count(leaf, sdref);
1093
1094 ret = add_direct_ref(ctx->fs_info, preftrees, 0, offset,
1095 ctx->bytenr, count, sc, GFP_NOFS);
1096 break;
1097 }
1098 case BTRFS_TREE_BLOCK_REF_KEY:
1099 ret = add_indirect_ref(ctx->fs_info, preftrees, offset,
1100 NULL, *info_level + 1,
1101 ctx->bytenr, 1, NULL, GFP_NOFS);
1102 break;
1103 case BTRFS_EXTENT_DATA_REF_KEY: {
1104 struct btrfs_extent_data_ref *dref;
1105 int count;
1106 u64 root;
1107
1108 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1109 count = btrfs_extent_data_ref_count(leaf, dref);
1110 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1111 dref);
1112 key.type = BTRFS_EXTENT_DATA_KEY;
1113 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1114
1115 if (sc && key.objectid != sc->inum &&
1116 !sc->have_delayed_delete_refs) {
1117 ret = BACKREF_FOUND_SHARED;
1118 break;
1119 }
1120
1121 root = btrfs_extent_data_ref_root(leaf, dref);
1122
1123 if (!ctx->skip_data_ref ||
1124 !ctx->skip_data_ref(root, key.objectid, key.offset,
1125 ctx->user_ctx))
1126 ret = add_indirect_ref(ctx->fs_info, preftrees,
1127 root, &key, 0, ctx->bytenr,
1128 count, sc, GFP_NOFS);
1129 break;
1130 }
1131 default:
1132 WARN_ON(1);
1133 }
1134 if (ret)
1135 return ret;
1136 ptr += btrfs_extent_inline_ref_size(type);
1137 }
1138
1139 return 0;
1140}
1141
1142/*
1143 * add all non-inline backrefs for bytenr to the list
1144 *
1145 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
1146 */
1147static int add_keyed_refs(struct btrfs_backref_walk_ctx *ctx,
1148 struct btrfs_root *extent_root,
1149 struct btrfs_path *path,
1150 int info_level, struct preftrees *preftrees,
1151 struct share_check *sc)
1152{
1153 struct btrfs_fs_info *fs_info = extent_root->fs_info;
1154 int ret;
1155 int slot;
1156 struct extent_buffer *leaf;
1157 struct btrfs_key key;
1158
1159 while (1) {
1160 ret = btrfs_next_item(extent_root, path);
1161 if (ret < 0)
1162 break;
1163 if (ret) {
1164 ret = 0;
1165 break;
1166 }
1167
1168 slot = path->slots[0];
1169 leaf = path->nodes[0];
1170 btrfs_item_key_to_cpu(leaf, &key, slot);
1171
1172 if (key.objectid != ctx->bytenr)
1173 break;
1174 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1175 continue;
1176 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1177 break;
1178
1179 switch (key.type) {
1180 case BTRFS_SHARED_BLOCK_REF_KEY:
1181 /* SHARED DIRECT METADATA backref */
1182 ret = add_direct_ref(fs_info, preftrees,
1183 info_level + 1, key.offset,
1184 ctx->bytenr, 1, NULL, GFP_NOFS);
1185 break;
1186 case BTRFS_SHARED_DATA_REF_KEY: {
1187 /* SHARED DIRECT FULL backref */
1188 struct btrfs_shared_data_ref *sdref;
1189 int count;
1190
1191 sdref = btrfs_item_ptr(leaf, slot,
1192 struct btrfs_shared_data_ref);
1193 count = btrfs_shared_data_ref_count(leaf, sdref);
1194 ret = add_direct_ref(fs_info, preftrees, 0,
1195 key.offset, ctx->bytenr, count,
1196 sc, GFP_NOFS);
1197 break;
1198 }
1199 case BTRFS_TREE_BLOCK_REF_KEY:
1200 /* NORMAL INDIRECT METADATA backref */
1201 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1202 NULL, info_level + 1, ctx->bytenr,
1203 1, NULL, GFP_NOFS);
1204 break;
1205 case BTRFS_EXTENT_DATA_REF_KEY: {
1206 /* NORMAL INDIRECT DATA backref */
1207 struct btrfs_extent_data_ref *dref;
1208 int count;
1209 u64 root;
1210
1211 dref = btrfs_item_ptr(leaf, slot,
1212 struct btrfs_extent_data_ref);
1213 count = btrfs_extent_data_ref_count(leaf, dref);
1214 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1215 dref);
1216 key.type = BTRFS_EXTENT_DATA_KEY;
1217 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1218
1219 if (sc && key.objectid != sc->inum &&
1220 !sc->have_delayed_delete_refs) {
1221 ret = BACKREF_FOUND_SHARED;
1222 break;
1223 }
1224
1225 root = btrfs_extent_data_ref_root(leaf, dref);
1226
1227 if (!ctx->skip_data_ref ||
1228 !ctx->skip_data_ref(root, key.objectid, key.offset,
1229 ctx->user_ctx))
1230 ret = add_indirect_ref(fs_info, preftrees, root,
1231 &key, 0, ctx->bytenr,
1232 count, sc, GFP_NOFS);
1233 break;
1234 }
1235 default:
1236 WARN_ON(1);
1237 }
1238 if (ret)
1239 return ret;
1240
1241 }
1242
1243 return ret;
1244}
1245
1246/*
1247 * The caller has joined a transaction or is holding a read lock on the
1248 * fs_info->commit_root_sem semaphore, so no need to worry about the root's last
1249 * snapshot field changing while updating or checking the cache.
1250 */
1251static bool lookup_backref_shared_cache(struct btrfs_backref_share_check_ctx *ctx,
1252 struct btrfs_root *root,
1253 u64 bytenr, int level, bool *is_shared)
1254{
1255 struct btrfs_backref_shared_cache_entry *entry;
1256
1257 if (!ctx->use_path_cache)
1258 return false;
1259
1260 if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL))
1261 return false;
1262
1263 /*
1264 * Level -1 is used for the data extent, which is not reliable to cache
1265 * because its reference count can increase or decrease without us
1266 * realizing. We cache results only for extent buffers that lead from
1267 * the root node down to the leaf with the file extent item.
1268 */
1269 ASSERT(level >= 0);
1270
1271 entry = &ctx->path_cache_entries[level];
1272
1273 /* Unused cache entry or being used for some other extent buffer. */
1274 if (entry->bytenr != bytenr)
1275 return false;
1276
1277 /*
1278 * We cached a false result, but the last snapshot generation of the
1279 * root changed, so we now have a snapshot. Don't trust the result.
1280 */
1281 if (!entry->is_shared &&
1282 entry->gen != btrfs_root_last_snapshot(&root->root_item))
1283 return false;
1284
1285 /*
1286 * If we cached a true result and the last generation used for dropping
1287 * a root changed, we can not trust the result, because the dropped root
1288 * could be a snapshot sharing this extent buffer.
1289 */
1290 if (entry->is_shared &&
1291 entry->gen != btrfs_get_last_root_drop_gen(root->fs_info))
1292 return false;
1293
1294 *is_shared = entry->is_shared;
1295 /*
1296 * If the node at this level is shared, than all nodes below are also
1297 * shared. Currently some of the nodes below may be marked as not shared
1298 * because we have just switched from one leaf to another, and switched
1299 * also other nodes above the leaf and below the current level, so mark
1300 * them as shared.
1301 */
1302 if (*is_shared) {
1303 for (int i = 0; i < level; i++) {
1304 ctx->path_cache_entries[i].is_shared = true;
1305 ctx->path_cache_entries[i].gen = entry->gen;
1306 }
1307 }
1308
1309 return true;
1310}
1311
1312/*
1313 * The caller has joined a transaction or is holding a read lock on the
1314 * fs_info->commit_root_sem semaphore, so no need to worry about the root's last
1315 * snapshot field changing while updating or checking the cache.
1316 */
1317static void store_backref_shared_cache(struct btrfs_backref_share_check_ctx *ctx,
1318 struct btrfs_root *root,
1319 u64 bytenr, int level, bool is_shared)
1320{
1321 struct btrfs_backref_shared_cache_entry *entry;
1322 u64 gen;
1323
1324 if (!ctx->use_path_cache)
1325 return;
1326
1327 if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL))
1328 return;
1329
1330 /*
1331 * Level -1 is used for the data extent, which is not reliable to cache
1332 * because its reference count can increase or decrease without us
1333 * realizing. We cache results only for extent buffers that lead from
1334 * the root node down to the leaf with the file extent item.
1335 */
1336 ASSERT(level >= 0);
1337
1338 if (is_shared)
1339 gen = btrfs_get_last_root_drop_gen(root->fs_info);
1340 else
1341 gen = btrfs_root_last_snapshot(&root->root_item);
1342
1343 entry = &ctx->path_cache_entries[level];
1344 entry->bytenr = bytenr;
1345 entry->is_shared = is_shared;
1346 entry->gen = gen;
1347
1348 /*
1349 * If we found an extent buffer is shared, set the cache result for all
1350 * extent buffers below it to true. As nodes in the path are COWed,
1351 * their sharedness is moved to their children, and if a leaf is COWed,
1352 * then the sharedness of a data extent becomes direct, the refcount of
1353 * data extent is increased in the extent item at the extent tree.
1354 */
1355 if (is_shared) {
1356 for (int i = 0; i < level; i++) {
1357 entry = &ctx->path_cache_entries[i];
1358 entry->is_shared = is_shared;
1359 entry->gen = gen;
1360 }
1361 }
1362}
1363
1364/*
1365 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1366 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1367 * indirect refs to their parent bytenr.
1368 * When roots are found, they're added to the roots list
1369 *
1370 * @ctx: Backref walking context object, must be not NULL.
1371 * @sc: If !NULL, then immediately return BACKREF_FOUND_SHARED when a
1372 * shared extent is detected.
1373 *
1374 * Otherwise this returns 0 for success and <0 for an error.
1375 *
1376 * FIXME some caching might speed things up
1377 */
1378static int find_parent_nodes(struct btrfs_backref_walk_ctx *ctx,
1379 struct share_check *sc)
1380{
1381 struct btrfs_root *root = btrfs_extent_root(ctx->fs_info, ctx->bytenr);
1382 struct btrfs_key key;
1383 struct btrfs_path *path;
1384 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1385 struct btrfs_delayed_ref_head *head;
1386 int info_level = 0;
1387 int ret;
1388 struct prelim_ref *ref;
1389 struct rb_node *node;
1390 struct extent_inode_elem *eie = NULL;
1391 struct preftrees preftrees = {
1392 .direct = PREFTREE_INIT,
1393 .indirect = PREFTREE_INIT,
1394 .indirect_missing_keys = PREFTREE_INIT
1395 };
1396
1397 /* Roots ulist is not needed when using a sharedness check context. */
1398 if (sc)
1399 ASSERT(ctx->roots == NULL);
1400
1401 key.objectid = ctx->bytenr;
1402 key.offset = (u64)-1;
1403 if (btrfs_fs_incompat(ctx->fs_info, SKINNY_METADATA))
1404 key.type = BTRFS_METADATA_ITEM_KEY;
1405 else
1406 key.type = BTRFS_EXTENT_ITEM_KEY;
1407
1408 path = btrfs_alloc_path();
1409 if (!path)
1410 return -ENOMEM;
1411 if (!ctx->trans) {
1412 path->search_commit_root = 1;
1413 path->skip_locking = 1;
1414 }
1415
1416 if (ctx->time_seq == BTRFS_SEQ_LAST)
1417 path->skip_locking = 1;
1418
1419again:
1420 head = NULL;
1421
1422 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1423 if (ret < 0)
1424 goto out;
1425 if (ret == 0) {
1426 /* This shouldn't happen, indicates a bug or fs corruption. */
1427 ASSERT(ret != 0);
1428 ret = -EUCLEAN;
1429 goto out;
1430 }
1431
1432 if (ctx->trans && likely(ctx->trans->type != __TRANS_DUMMY) &&
1433 ctx->time_seq != BTRFS_SEQ_LAST) {
1434 /*
1435 * We have a specific time_seq we care about and trans which
1436 * means we have the path lock, we need to grab the ref head and
1437 * lock it so we have a consistent view of the refs at the given
1438 * time.
1439 */
1440 delayed_refs = &ctx->trans->transaction->delayed_refs;
1441 spin_lock(&delayed_refs->lock);
1442 head = btrfs_find_delayed_ref_head(delayed_refs, ctx->bytenr);
1443 if (head) {
1444 if (!mutex_trylock(&head->mutex)) {
1445 refcount_inc(&head->refs);
1446 spin_unlock(&delayed_refs->lock);
1447
1448 btrfs_release_path(path);
1449
1450 /*
1451 * Mutex was contended, block until it's
1452 * released and try again
1453 */
1454 mutex_lock(&head->mutex);
1455 mutex_unlock(&head->mutex);
1456 btrfs_put_delayed_ref_head(head);
1457 goto again;
1458 }
1459 spin_unlock(&delayed_refs->lock);
1460 ret = add_delayed_refs(ctx->fs_info, head, ctx->time_seq,
1461 &preftrees, sc);
1462 mutex_unlock(&head->mutex);
1463 if (ret)
1464 goto out;
1465 } else {
1466 spin_unlock(&delayed_refs->lock);
1467 }
1468 }
1469
1470 if (path->slots[0]) {
1471 struct extent_buffer *leaf;
1472 int slot;
1473
1474 path->slots[0]--;
1475 leaf = path->nodes[0];
1476 slot = path->slots[0];
1477 btrfs_item_key_to_cpu(leaf, &key, slot);
1478 if (key.objectid == ctx->bytenr &&
1479 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1480 key.type == BTRFS_METADATA_ITEM_KEY)) {
1481 ret = add_inline_refs(ctx, path, &info_level,
1482 &preftrees, sc);
1483 if (ret)
1484 goto out;
1485 ret = add_keyed_refs(ctx, root, path, info_level,
1486 &preftrees, sc);
1487 if (ret)
1488 goto out;
1489 }
1490 }
1491
1492 /*
1493 * If we have a share context and we reached here, it means the extent
1494 * is not directly shared (no multiple reference items for it),
1495 * otherwise we would have exited earlier with a return value of
1496 * BACKREF_FOUND_SHARED after processing delayed references or while
1497 * processing inline or keyed references from the extent tree.
1498 * The extent may however be indirectly shared through shared subtrees
1499 * as a result from creating snapshots, so we determine below what is
1500 * its parent node, in case we are dealing with a metadata extent, or
1501 * what's the leaf (or leaves), from a fs tree, that has a file extent
1502 * item pointing to it in case we are dealing with a data extent.
1503 */
1504 ASSERT(extent_is_shared(sc) == 0);
1505
1506 /*
1507 * If we are here for a data extent and we have a share_check structure
1508 * it means the data extent is not directly shared (does not have
1509 * multiple reference items), so we have to check if a path in the fs
1510 * tree (going from the root node down to the leaf that has the file
1511 * extent item pointing to the data extent) is shared, that is, if any
1512 * of the extent buffers in the path is referenced by other trees.
1513 */
1514 if (sc && ctx->bytenr == sc->data_bytenr) {
1515 /*
1516 * If our data extent is from a generation more recent than the
1517 * last generation used to snapshot the root, then we know that
1518 * it can not be shared through subtrees, so we can skip
1519 * resolving indirect references, there's no point in
1520 * determining the extent buffers for the path from the fs tree
1521 * root node down to the leaf that has the file extent item that
1522 * points to the data extent.
1523 */
1524 if (sc->data_extent_gen >
1525 btrfs_root_last_snapshot(&sc->root->root_item)) {
1526 ret = BACKREF_FOUND_NOT_SHARED;
1527 goto out;
1528 }
1529
1530 /*
1531 * If we are only determining if a data extent is shared or not
1532 * and the corresponding file extent item is located in the same
1533 * leaf as the previous file extent item, we can skip resolving
1534 * indirect references for a data extent, since the fs tree path
1535 * is the same (same leaf, so same path). We skip as long as the
1536 * cached result for the leaf is valid and only if there's only
1537 * one file extent item pointing to the data extent, because in
1538 * the case of multiple file extent items, they may be located
1539 * in different leaves and therefore we have multiple paths.
1540 */
1541 if (sc->ctx->curr_leaf_bytenr == sc->ctx->prev_leaf_bytenr &&
1542 sc->self_ref_count == 1) {
1543 bool cached;
1544 bool is_shared;
1545
1546 cached = lookup_backref_shared_cache(sc->ctx, sc->root,
1547 sc->ctx->curr_leaf_bytenr,
1548 0, &is_shared);
1549 if (cached) {
1550 if (is_shared)
1551 ret = BACKREF_FOUND_SHARED;
1552 else
1553 ret = BACKREF_FOUND_NOT_SHARED;
1554 goto out;
1555 }
1556 }
1557 }
1558
1559 btrfs_release_path(path);
1560
1561 ret = add_missing_keys(ctx->fs_info, &preftrees, path->skip_locking == 0);
1562 if (ret)
1563 goto out;
1564
1565 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root));
1566
1567 ret = resolve_indirect_refs(ctx, path, &preftrees, sc);
1568 if (ret)
1569 goto out;
1570
1571 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root));
1572
1573 /*
1574 * This walks the tree of merged and resolved refs. Tree blocks are
1575 * read in as needed. Unique entries are added to the ulist, and
1576 * the list of found roots is updated.
1577 *
1578 * We release the entire tree in one go before returning.
1579 */
1580 node = rb_first_cached(&preftrees.direct.root);
1581 while (node) {
1582 ref = rb_entry(node, struct prelim_ref, rbnode);
1583 node = rb_next(&ref->rbnode);
1584 /*
1585 * ref->count < 0 can happen here if there are delayed
1586 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1587 * prelim_ref_insert() relies on this when merging
1588 * identical refs to keep the overall count correct.
1589 * prelim_ref_insert() will merge only those refs
1590 * which compare identically. Any refs having
1591 * e.g. different offsets would not be merged,
1592 * and would retain their original ref->count < 0.
1593 */
1594 if (ctx->roots && ref->count && ref->root_id && ref->parent == 0) {
1595 /* no parent == root of tree */
1596 ret = ulist_add(ctx->roots, ref->root_id, 0, GFP_NOFS);
1597 if (ret < 0)
1598 goto out;
1599 }
1600 if (ref->count && ref->parent) {
1601 if (!ctx->ignore_extent_item_pos && !ref->inode_list &&
1602 ref->level == 0) {
1603 struct btrfs_tree_parent_check check = { 0 };
1604 struct extent_buffer *eb;
1605
1606 check.level = ref->level;
1607
1608 eb = read_tree_block(ctx->fs_info, ref->parent,
1609 &check);
1610 if (IS_ERR(eb)) {
1611 ret = PTR_ERR(eb);
1612 goto out;
1613 }
1614 if (!extent_buffer_uptodate(eb)) {
1615 free_extent_buffer(eb);
1616 ret = -EIO;
1617 goto out;
1618 }
1619
1620 if (!path->skip_locking)
1621 btrfs_tree_read_lock(eb);
1622 ret = find_extent_in_eb(ctx, eb, &eie);
1623 if (!path->skip_locking)
1624 btrfs_tree_read_unlock(eb);
1625 free_extent_buffer(eb);
1626 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
1627 ret < 0)
1628 goto out;
1629 ref->inode_list = eie;
1630 /*
1631 * We transferred the list ownership to the ref,
1632 * so set to NULL to avoid a double free in case
1633 * an error happens after this.
1634 */
1635 eie = NULL;
1636 }
1637 ret = ulist_add_merge_ptr(ctx->refs, ref->parent,
1638 ref->inode_list,
1639 (void **)&eie, GFP_NOFS);
1640 if (ret < 0)
1641 goto out;
1642 if (!ret && !ctx->ignore_extent_item_pos) {
1643 /*
1644 * We've recorded that parent, so we must extend
1645 * its inode list here.
1646 *
1647 * However if there was corruption we may not
1648 * have found an eie, return an error in this
1649 * case.
1650 */
1651 ASSERT(eie);
1652 if (!eie) {
1653 ret = -EUCLEAN;
1654 goto out;
1655 }
1656 while (eie->next)
1657 eie = eie->next;
1658 eie->next = ref->inode_list;
1659 }
1660 eie = NULL;
1661 /*
1662 * We have transferred the inode list ownership from
1663 * this ref to the ref we added to the 'refs' ulist.
1664 * So set this ref's inode list to NULL to avoid
1665 * use-after-free when our caller uses it or double
1666 * frees in case an error happens before we return.
1667 */
1668 ref->inode_list = NULL;
1669 }
1670 cond_resched();
1671 }
1672
1673out:
1674 btrfs_free_path(path);
1675
1676 prelim_release(&preftrees.direct);
1677 prelim_release(&preftrees.indirect);
1678 prelim_release(&preftrees.indirect_missing_keys);
1679
1680 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
1681 free_inode_elem_list(eie);
1682 return ret;
1683}
1684
1685/*
1686 * Finds all leaves with a reference to the specified combination of
1687 * @ctx->bytenr and @ctx->extent_item_pos. The bytenr of the found leaves are
1688 * added to the ulist at @ctx->refs, and that ulist is allocated by this
1689 * function. The caller should free the ulist with free_leaf_list() if
1690 * @ctx->ignore_extent_item_pos is false, otherwise a fimple ulist_free() is
1691 * enough.
1692 *
1693 * Returns 0 on success and < 0 on error. On error @ctx->refs is not allocated.
1694 */
1695int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx)
1696{
1697 int ret;
1698
1699 ASSERT(ctx->refs == NULL);
1700
1701 ctx->refs = ulist_alloc(GFP_NOFS);
1702 if (!ctx->refs)
1703 return -ENOMEM;
1704
1705 ret = find_parent_nodes(ctx, NULL);
1706 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
1707 (ret < 0 && ret != -ENOENT)) {
1708 free_leaf_list(ctx->refs);
1709 ctx->refs = NULL;
1710 return ret;
1711 }
1712
1713 return 0;
1714}
1715
1716/*
1717 * Walk all backrefs for a given extent to find all roots that reference this
1718 * extent. Walking a backref means finding all extents that reference this
1719 * extent and in turn walk the backrefs of those, too. Naturally this is a
1720 * recursive process, but here it is implemented in an iterative fashion: We
1721 * find all referencing extents for the extent in question and put them on a
1722 * list. In turn, we find all referencing extents for those, further appending
1723 * to the list. The way we iterate the list allows adding more elements after
1724 * the current while iterating. The process stops when we reach the end of the
1725 * list.
1726 *
1727 * Found roots are added to @ctx->roots, which is allocated by this function if
1728 * it points to NULL, in which case the caller is responsible for freeing it
1729 * after it's not needed anymore.
1730 * This function requires @ctx->refs to be NULL, as it uses it for allocating a
1731 * ulist to do temporary work, and frees it before returning.
1732 *
1733 * Returns 0 on success, < 0 on error.
1734 */
1735static int btrfs_find_all_roots_safe(struct btrfs_backref_walk_ctx *ctx)
1736{
1737 const u64 orig_bytenr = ctx->bytenr;
1738 const bool orig_ignore_extent_item_pos = ctx->ignore_extent_item_pos;
1739 bool roots_ulist_allocated = false;
1740 struct ulist_iterator uiter;
1741 int ret = 0;
1742
1743 ASSERT(ctx->refs == NULL);
1744
1745 ctx->refs = ulist_alloc(GFP_NOFS);
1746 if (!ctx->refs)
1747 return -ENOMEM;
1748
1749 if (!ctx->roots) {
1750 ctx->roots = ulist_alloc(GFP_NOFS);
1751 if (!ctx->roots) {
1752 ulist_free(ctx->refs);
1753 ctx->refs = NULL;
1754 return -ENOMEM;
1755 }
1756 roots_ulist_allocated = true;
1757 }
1758
1759 ctx->ignore_extent_item_pos = true;
1760
1761 ULIST_ITER_INIT(&uiter);
1762 while (1) {
1763 struct ulist_node *node;
1764
1765 ret = find_parent_nodes(ctx, NULL);
1766 if (ret < 0 && ret != -ENOENT) {
1767 if (roots_ulist_allocated) {
1768 ulist_free(ctx->roots);
1769 ctx->roots = NULL;
1770 }
1771 break;
1772 }
1773 ret = 0;
1774 node = ulist_next(ctx->refs, &uiter);
1775 if (!node)
1776 break;
1777 ctx->bytenr = node->val;
1778 cond_resched();
1779 }
1780
1781 ulist_free(ctx->refs);
1782 ctx->refs = NULL;
1783 ctx->bytenr = orig_bytenr;
1784 ctx->ignore_extent_item_pos = orig_ignore_extent_item_pos;
1785
1786 return ret;
1787}
1788
1789int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx,
1790 bool skip_commit_root_sem)
1791{
1792 int ret;
1793
1794 if (!ctx->trans && !skip_commit_root_sem)
1795 down_read(&ctx->fs_info->commit_root_sem);
1796 ret = btrfs_find_all_roots_safe(ctx);
1797 if (!ctx->trans && !skip_commit_root_sem)
1798 up_read(&ctx->fs_info->commit_root_sem);
1799 return ret;
1800}
1801
1802struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void)
1803{
1804 struct btrfs_backref_share_check_ctx *ctx;
1805
1806 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
1807 if (!ctx)
1808 return NULL;
1809
1810 ulist_init(&ctx->refs);
1811
1812 return ctx;
1813}
1814
1815void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx)
1816{
1817 if (!ctx)
1818 return;
1819
1820 ulist_release(&ctx->refs);
1821 kfree(ctx);
1822}
1823
1824/*
1825 * Check if a data extent is shared or not.
1826 *
1827 * @inode: The inode whose extent we are checking.
1828 * @bytenr: Logical bytenr of the extent we are checking.
1829 * @extent_gen: Generation of the extent (file extent item) or 0 if it is
1830 * not known.
1831 * @ctx: A backref sharedness check context.
1832 *
1833 * btrfs_is_data_extent_shared uses the backref walking code but will short
1834 * circuit as soon as it finds a root or inode that doesn't match the
1835 * one passed in. This provides a significant performance benefit for
1836 * callers (such as fiemap) which want to know whether the extent is
1837 * shared but do not need a ref count.
1838 *
1839 * This attempts to attach to the running transaction in order to account for
1840 * delayed refs, but continues on even when no running transaction exists.
1841 *
1842 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1843 */
1844int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,
1845 u64 extent_gen,
1846 struct btrfs_backref_share_check_ctx *ctx)
1847{
1848 struct btrfs_backref_walk_ctx walk_ctx = { 0 };
1849 struct btrfs_root *root = inode->root;
1850 struct btrfs_fs_info *fs_info = root->fs_info;
1851 struct btrfs_trans_handle *trans;
1852 struct ulist_iterator uiter;
1853 struct ulist_node *node;
1854 struct btrfs_seq_list elem = BTRFS_SEQ_LIST_INIT(elem);
1855 int ret = 0;
1856 struct share_check shared = {
1857 .ctx = ctx,
1858 .root = root,
1859 .inum = btrfs_ino(inode),
1860 .data_bytenr = bytenr,
1861 .data_extent_gen = extent_gen,
1862 .share_count = 0,
1863 .self_ref_count = 0,
1864 .have_delayed_delete_refs = false,
1865 };
1866 int level;
1867
1868 for (int i = 0; i < BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE; i++) {
1869 if (ctx->prev_extents_cache[i].bytenr == bytenr)
1870 return ctx->prev_extents_cache[i].is_shared;
1871 }
1872
1873 ulist_init(&ctx->refs);
1874
1875 trans = btrfs_join_transaction_nostart(root);
1876 if (IS_ERR(trans)) {
1877 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
1878 ret = PTR_ERR(trans);
1879 goto out;
1880 }
1881 trans = NULL;
1882 down_read(&fs_info->commit_root_sem);
1883 } else {
1884 btrfs_get_tree_mod_seq(fs_info, &elem);
1885 walk_ctx.time_seq = elem.seq;
1886 }
1887
1888 walk_ctx.ignore_extent_item_pos = true;
1889 walk_ctx.trans = trans;
1890 walk_ctx.fs_info = fs_info;
1891 walk_ctx.refs = &ctx->refs;
1892
1893 /* -1 means we are in the bytenr of the data extent. */
1894 level = -1;
1895 ULIST_ITER_INIT(&uiter);
1896 ctx->use_path_cache = true;
1897 while (1) {
1898 bool is_shared;
1899 bool cached;
1900
1901 walk_ctx.bytenr = bytenr;
1902 ret = find_parent_nodes(&walk_ctx, &shared);
1903 if (ret == BACKREF_FOUND_SHARED ||
1904 ret == BACKREF_FOUND_NOT_SHARED) {
1905 /* If shared must return 1, otherwise return 0. */
1906 ret = (ret == BACKREF_FOUND_SHARED) ? 1 : 0;
1907 if (level >= 0)
1908 store_backref_shared_cache(ctx, root, bytenr,
1909 level, ret == 1);
1910 break;
1911 }
1912 if (ret < 0 && ret != -ENOENT)
1913 break;
1914 ret = 0;
1915
1916 /*
1917 * If our data extent was not directly shared (without multiple
1918 * reference items), than it might have a single reference item
1919 * with a count > 1 for the same offset, which means there are 2
1920 * (or more) file extent items that point to the data extent -
1921 * this happens when a file extent item needs to be split and
1922 * then one item gets moved to another leaf due to a b+tree leaf
1923 * split when inserting some item. In this case the file extent
1924 * items may be located in different leaves and therefore some
1925 * of the leaves may be referenced through shared subtrees while
1926 * others are not. Since our extent buffer cache only works for
1927 * a single path (by far the most common case and simpler to
1928 * deal with), we can not use it if we have multiple leaves
1929 * (which implies multiple paths).
1930 */
1931 if (level == -1 && ctx->refs.nnodes > 1)
1932 ctx->use_path_cache = false;
1933
1934 if (level >= 0)
1935 store_backref_shared_cache(ctx, root, bytenr,
1936 level, false);
1937 node = ulist_next(&ctx->refs, &uiter);
1938 if (!node)
1939 break;
1940 bytenr = node->val;
1941 level++;
1942 cached = lookup_backref_shared_cache(ctx, root, bytenr, level,
1943 &is_shared);
1944 if (cached) {
1945 ret = (is_shared ? 1 : 0);
1946 break;
1947 }
1948 shared.share_count = 0;
1949 shared.have_delayed_delete_refs = false;
1950 cond_resched();
1951 }
1952
1953 /*
1954 * Cache the sharedness result for the data extent if we know our inode
1955 * has more than 1 file extent item that refers to the data extent.
1956 */
1957 if (ret >= 0 && shared.self_ref_count > 1) {
1958 int slot = ctx->prev_extents_cache_slot;
1959
1960 ctx->prev_extents_cache[slot].bytenr = shared.data_bytenr;
1961 ctx->prev_extents_cache[slot].is_shared = (ret == 1);
1962
1963 slot = (slot + 1) % BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE;
1964 ctx->prev_extents_cache_slot = slot;
1965 }
1966
1967 if (trans) {
1968 btrfs_put_tree_mod_seq(fs_info, &elem);
1969 btrfs_end_transaction(trans);
1970 } else {
1971 up_read(&fs_info->commit_root_sem);
1972 }
1973out:
1974 ulist_release(&ctx->refs);
1975 ctx->prev_leaf_bytenr = ctx->curr_leaf_bytenr;
1976
1977 return ret;
1978}
1979
1980int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1981 u64 start_off, struct btrfs_path *path,
1982 struct btrfs_inode_extref **ret_extref,
1983 u64 *found_off)
1984{
1985 int ret, slot;
1986 struct btrfs_key key;
1987 struct btrfs_key found_key;
1988 struct btrfs_inode_extref *extref;
1989 const struct extent_buffer *leaf;
1990 unsigned long ptr;
1991
1992 key.objectid = inode_objectid;
1993 key.type = BTRFS_INODE_EXTREF_KEY;
1994 key.offset = start_off;
1995
1996 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1997 if (ret < 0)
1998 return ret;
1999
2000 while (1) {
2001 leaf = path->nodes[0];
2002 slot = path->slots[0];
2003 if (slot >= btrfs_header_nritems(leaf)) {
2004 /*
2005 * If the item at offset is not found,
2006 * btrfs_search_slot will point us to the slot
2007 * where it should be inserted. In our case
2008 * that will be the slot directly before the
2009 * next INODE_REF_KEY_V2 item. In the case
2010 * that we're pointing to the last slot in a
2011 * leaf, we must move one leaf over.
2012 */
2013 ret = btrfs_next_leaf(root, path);
2014 if (ret) {
2015 if (ret >= 1)
2016 ret = -ENOENT;
2017 break;
2018 }
2019 continue;
2020 }
2021
2022 btrfs_item_key_to_cpu(leaf, &found_key, slot);
2023
2024 /*
2025 * Check that we're still looking at an extended ref key for
2026 * this particular objectid. If we have different
2027 * objectid or type then there are no more to be found
2028 * in the tree and we can exit.
2029 */
2030 ret = -ENOENT;
2031 if (found_key.objectid != inode_objectid)
2032 break;
2033 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
2034 break;
2035
2036 ret = 0;
2037 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2038 extref = (struct btrfs_inode_extref *)ptr;
2039 *ret_extref = extref;
2040 if (found_off)
2041 *found_off = found_key.offset;
2042 break;
2043 }
2044
2045 return ret;
2046}
2047
2048/*
2049 * this iterates to turn a name (from iref/extref) into a full filesystem path.
2050 * Elements of the path are separated by '/' and the path is guaranteed to be
2051 * 0-terminated. the path is only given within the current file system.
2052 * Therefore, it never starts with a '/'. the caller is responsible to provide
2053 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
2054 * the start point of the resulting string is returned. this pointer is within
2055 * dest, normally.
2056 * in case the path buffer would overflow, the pointer is decremented further
2057 * as if output was written to the buffer, though no more output is actually
2058 * generated. that way, the caller can determine how much space would be
2059 * required for the path to fit into the buffer. in that case, the returned
2060 * value will be smaller than dest. callers must check this!
2061 */
2062char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
2063 u32 name_len, unsigned long name_off,
2064 struct extent_buffer *eb_in, u64 parent,
2065 char *dest, u32 size)
2066{
2067 int slot;
2068 u64 next_inum;
2069 int ret;
2070 s64 bytes_left = ((s64)size) - 1;
2071 struct extent_buffer *eb = eb_in;
2072 struct btrfs_key found_key;
2073 struct btrfs_inode_ref *iref;
2074
2075 if (bytes_left >= 0)
2076 dest[bytes_left] = '\0';
2077
2078 while (1) {
2079 bytes_left -= name_len;
2080 if (bytes_left >= 0)
2081 read_extent_buffer(eb, dest + bytes_left,
2082 name_off, name_len);
2083 if (eb != eb_in) {
2084 if (!path->skip_locking)
2085 btrfs_tree_read_unlock(eb);
2086 free_extent_buffer(eb);
2087 }
2088 ret = btrfs_find_item(fs_root, path, parent, 0,
2089 BTRFS_INODE_REF_KEY, &found_key);
2090 if (ret > 0)
2091 ret = -ENOENT;
2092 if (ret)
2093 break;
2094
2095 next_inum = found_key.offset;
2096
2097 /* regular exit ahead */
2098 if (parent == next_inum)
2099 break;
2100
2101 slot = path->slots[0];
2102 eb = path->nodes[0];
2103 /* make sure we can use eb after releasing the path */
2104 if (eb != eb_in) {
2105 path->nodes[0] = NULL;
2106 path->locks[0] = 0;
2107 }
2108 btrfs_release_path(path);
2109 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2110
2111 name_len = btrfs_inode_ref_name_len(eb, iref);
2112 name_off = (unsigned long)(iref + 1);
2113
2114 parent = next_inum;
2115 --bytes_left;
2116 if (bytes_left >= 0)
2117 dest[bytes_left] = '/';
2118 }
2119
2120 btrfs_release_path(path);
2121
2122 if (ret)
2123 return ERR_PTR(ret);
2124
2125 return dest + bytes_left;
2126}
2127
2128/*
2129 * this makes the path point to (logical EXTENT_ITEM *)
2130 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
2131 * tree blocks and <0 on error.
2132 */
2133int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
2134 struct btrfs_path *path, struct btrfs_key *found_key,
2135 u64 *flags_ret)
2136{
2137 struct btrfs_root *extent_root = btrfs_extent_root(fs_info, logical);
2138 int ret;
2139 u64 flags;
2140 u64 size = 0;
2141 u32 item_size;
2142 const struct extent_buffer *eb;
2143 struct btrfs_extent_item *ei;
2144 struct btrfs_key key;
2145
2146 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2147 key.type = BTRFS_METADATA_ITEM_KEY;
2148 else
2149 key.type = BTRFS_EXTENT_ITEM_KEY;
2150 key.objectid = logical;
2151 key.offset = (u64)-1;
2152
2153 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
2154 if (ret < 0)
2155 return ret;
2156
2157 ret = btrfs_previous_extent_item(extent_root, path, 0);
2158 if (ret) {
2159 if (ret > 0)
2160 ret = -ENOENT;
2161 return ret;
2162 }
2163 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
2164 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
2165 size = fs_info->nodesize;
2166 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
2167 size = found_key->offset;
2168
2169 if (found_key->objectid > logical ||
2170 found_key->objectid + size <= logical) {
2171 btrfs_debug(fs_info,
2172 "logical %llu is not within any extent", logical);
2173 return -ENOENT;
2174 }
2175
2176 eb = path->nodes[0];
2177 item_size = btrfs_item_size(eb, path->slots[0]);
2178 BUG_ON(item_size < sizeof(*ei));
2179
2180 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
2181 flags = btrfs_extent_flags(eb, ei);
2182
2183 btrfs_debug(fs_info,
2184 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
2185 logical, logical - found_key->objectid, found_key->objectid,
2186 found_key->offset, flags, item_size);
2187
2188 WARN_ON(!flags_ret);
2189 if (flags_ret) {
2190 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2191 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
2192 else if (flags & BTRFS_EXTENT_FLAG_DATA)
2193 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
2194 else
2195 BUG();
2196 return 0;
2197 }
2198
2199 return -EIO;
2200}
2201
2202/*
2203 * helper function to iterate extent inline refs. ptr must point to a 0 value
2204 * for the first call and may be modified. it is used to track state.
2205 * if more refs exist, 0 is returned and the next call to
2206 * get_extent_inline_ref must pass the modified ptr parameter to get the
2207 * next ref. after the last ref was processed, 1 is returned.
2208 * returns <0 on error
2209 */
2210static int get_extent_inline_ref(unsigned long *ptr,
2211 const struct extent_buffer *eb,
2212 const struct btrfs_key *key,
2213 const struct btrfs_extent_item *ei,
2214 u32 item_size,
2215 struct btrfs_extent_inline_ref **out_eiref,
2216 int *out_type)
2217{
2218 unsigned long end;
2219 u64 flags;
2220 struct btrfs_tree_block_info *info;
2221
2222 if (!*ptr) {
2223 /* first call */
2224 flags = btrfs_extent_flags(eb, ei);
2225 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2226 if (key->type == BTRFS_METADATA_ITEM_KEY) {
2227 /* a skinny metadata extent */
2228 *out_eiref =
2229 (struct btrfs_extent_inline_ref *)(ei + 1);
2230 } else {
2231 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
2232 info = (struct btrfs_tree_block_info *)(ei + 1);
2233 *out_eiref =
2234 (struct btrfs_extent_inline_ref *)(info + 1);
2235 }
2236 } else {
2237 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
2238 }
2239 *ptr = (unsigned long)*out_eiref;
2240 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
2241 return -ENOENT;
2242 }
2243
2244 end = (unsigned long)ei + item_size;
2245 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
2246 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
2247 BTRFS_REF_TYPE_ANY);
2248 if (*out_type == BTRFS_REF_TYPE_INVALID)
2249 return -EUCLEAN;
2250
2251 *ptr += btrfs_extent_inline_ref_size(*out_type);
2252 WARN_ON(*ptr > end);
2253 if (*ptr == end)
2254 return 1; /* last */
2255
2256 return 0;
2257}
2258
2259/*
2260 * reads the tree block backref for an extent. tree level and root are returned
2261 * through out_level and out_root. ptr must point to a 0 value for the first
2262 * call and may be modified (see get_extent_inline_ref comment).
2263 * returns 0 if data was provided, 1 if there was no more data to provide or
2264 * <0 on error.
2265 */
2266int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
2267 struct btrfs_key *key, struct btrfs_extent_item *ei,
2268 u32 item_size, u64 *out_root, u8 *out_level)
2269{
2270 int ret;
2271 int type;
2272 struct btrfs_extent_inline_ref *eiref;
2273
2274 if (*ptr == (unsigned long)-1)
2275 return 1;
2276
2277 while (1) {
2278 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
2279 &eiref, &type);
2280 if (ret < 0)
2281 return ret;
2282
2283 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
2284 type == BTRFS_SHARED_BLOCK_REF_KEY)
2285 break;
2286
2287 if (ret == 1)
2288 return 1;
2289 }
2290
2291 /* we can treat both ref types equally here */
2292 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
2293
2294 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
2295 struct btrfs_tree_block_info *info;
2296
2297 info = (struct btrfs_tree_block_info *)(ei + 1);
2298 *out_level = btrfs_tree_block_level(eb, info);
2299 } else {
2300 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
2301 *out_level = (u8)key->offset;
2302 }
2303
2304 if (ret == 1)
2305 *ptr = (unsigned long)-1;
2306
2307 return 0;
2308}
2309
2310static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
2311 struct extent_inode_elem *inode_list,
2312 u64 root, u64 extent_item_objectid,
2313 iterate_extent_inodes_t *iterate, void *ctx)
2314{
2315 struct extent_inode_elem *eie;
2316 int ret = 0;
2317
2318 for (eie = inode_list; eie; eie = eie->next) {
2319 btrfs_debug(fs_info,
2320 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
2321 extent_item_objectid, eie->inum,
2322 eie->offset, root);
2323 ret = iterate(eie->inum, eie->offset, eie->num_bytes, root, ctx);
2324 if (ret) {
2325 btrfs_debug(fs_info,
2326 "stopping iteration for %llu due to ret=%d",
2327 extent_item_objectid, ret);
2328 break;
2329 }
2330 }
2331
2332 return ret;
2333}
2334
2335/*
2336 * calls iterate() for every inode that references the extent identified by
2337 * the given parameters.
2338 * when the iterator function returns a non-zero value, iteration stops.
2339 */
2340int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx,
2341 bool search_commit_root,
2342 iterate_extent_inodes_t *iterate, void *user_ctx)
2343{
2344 int ret;
2345 struct ulist *refs;
2346 struct ulist_node *ref_node;
2347 struct btrfs_seq_list seq_elem = BTRFS_SEQ_LIST_INIT(seq_elem);
2348 struct ulist_iterator ref_uiter;
2349
2350 btrfs_debug(ctx->fs_info, "resolving all inodes for extent %llu",
2351 ctx->bytenr);
2352
2353 ASSERT(ctx->trans == NULL);
2354 ASSERT(ctx->roots == NULL);
2355
2356 if (!search_commit_root) {
2357 struct btrfs_trans_handle *trans;
2358
2359 trans = btrfs_attach_transaction(ctx->fs_info->tree_root);
2360 if (IS_ERR(trans)) {
2361 if (PTR_ERR(trans) != -ENOENT &&
2362 PTR_ERR(trans) != -EROFS)
2363 return PTR_ERR(trans);
2364 trans = NULL;
2365 }
2366 ctx->trans = trans;
2367 }
2368
2369 if (ctx->trans) {
2370 btrfs_get_tree_mod_seq(ctx->fs_info, &seq_elem);
2371 ctx->time_seq = seq_elem.seq;
2372 } else {
2373 down_read(&ctx->fs_info->commit_root_sem);
2374 }
2375
2376 ret = btrfs_find_all_leafs(ctx);
2377 if (ret)
2378 goto out;
2379 refs = ctx->refs;
2380 ctx->refs = NULL;
2381
2382 ULIST_ITER_INIT(&ref_uiter);
2383 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
2384 const u64 leaf_bytenr = ref_node->val;
2385 struct ulist_node *root_node;
2386 struct ulist_iterator root_uiter;
2387 struct extent_inode_elem *inode_list;
2388
2389 inode_list = (struct extent_inode_elem *)(uintptr_t)ref_node->aux;
2390
2391 if (ctx->cache_lookup) {
2392 const u64 *root_ids;
2393 int root_count;
2394 bool cached;
2395
2396 cached = ctx->cache_lookup(leaf_bytenr, ctx->user_ctx,
2397 &root_ids, &root_count);
2398 if (cached) {
2399 for (int i = 0; i < root_count; i++) {
2400 ret = iterate_leaf_refs(ctx->fs_info,
2401 inode_list,
2402 root_ids[i],
2403 leaf_bytenr,
2404 iterate,
2405 user_ctx);
2406 if (ret)
2407 break;
2408 }
2409 continue;
2410 }
2411 }
2412
2413 if (!ctx->roots) {
2414 ctx->roots = ulist_alloc(GFP_NOFS);
2415 if (!ctx->roots) {
2416 ret = -ENOMEM;
2417 break;
2418 }
2419 }
2420
2421 ctx->bytenr = leaf_bytenr;
2422 ret = btrfs_find_all_roots_safe(ctx);
2423 if (ret)
2424 break;
2425
2426 if (ctx->cache_store)
2427 ctx->cache_store(leaf_bytenr, ctx->roots, ctx->user_ctx);
2428
2429 ULIST_ITER_INIT(&root_uiter);
2430 while (!ret && (root_node = ulist_next(ctx->roots, &root_uiter))) {
2431 btrfs_debug(ctx->fs_info,
2432 "root %llu references leaf %llu, data list %#llx",
2433 root_node->val, ref_node->val,
2434 ref_node->aux);
2435 ret = iterate_leaf_refs(ctx->fs_info, inode_list,
2436 root_node->val, ctx->bytenr,
2437 iterate, user_ctx);
2438 }
2439 ulist_reinit(ctx->roots);
2440 }
2441
2442 free_leaf_list(refs);
2443out:
2444 if (ctx->trans) {
2445 btrfs_put_tree_mod_seq(ctx->fs_info, &seq_elem);
2446 btrfs_end_transaction(ctx->trans);
2447 ctx->trans = NULL;
2448 } else {
2449 up_read(&ctx->fs_info->commit_root_sem);
2450 }
2451
2452 ulist_free(ctx->roots);
2453 ctx->roots = NULL;
2454
2455 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP)
2456 ret = 0;
2457
2458 return ret;
2459}
2460
2461static int build_ino_list(u64 inum, u64 offset, u64 num_bytes, u64 root, void *ctx)
2462{
2463 struct btrfs_data_container *inodes = ctx;
2464 const size_t c = 3 * sizeof(u64);
2465
2466 if (inodes->bytes_left >= c) {
2467 inodes->bytes_left -= c;
2468 inodes->val[inodes->elem_cnt] = inum;
2469 inodes->val[inodes->elem_cnt + 1] = offset;
2470 inodes->val[inodes->elem_cnt + 2] = root;
2471 inodes->elem_cnt += 3;
2472 } else {
2473 inodes->bytes_missing += c - inodes->bytes_left;
2474 inodes->bytes_left = 0;
2475 inodes->elem_missed += 3;
2476 }
2477
2478 return 0;
2479}
2480
2481int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
2482 struct btrfs_path *path,
2483 void *ctx, bool ignore_offset)
2484{
2485 struct btrfs_backref_walk_ctx walk_ctx = { 0 };
2486 int ret;
2487 u64 flags = 0;
2488 struct btrfs_key found_key;
2489 int search_commit_root = path->search_commit_root;
2490
2491 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
2492 btrfs_release_path(path);
2493 if (ret < 0)
2494 return ret;
2495 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2496 return -EINVAL;
2497
2498 walk_ctx.bytenr = found_key.objectid;
2499 if (ignore_offset)
2500 walk_ctx.ignore_extent_item_pos = true;
2501 else
2502 walk_ctx.extent_item_pos = logical - found_key.objectid;
2503 walk_ctx.fs_info = fs_info;
2504
2505 return iterate_extent_inodes(&walk_ctx, search_commit_root,
2506 build_ino_list, ctx);
2507}
2508
2509static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2510 struct extent_buffer *eb, struct inode_fs_paths *ipath);
2511
2512static int iterate_inode_refs(u64 inum, struct inode_fs_paths *ipath)
2513{
2514 int ret = 0;
2515 int slot;
2516 u32 cur;
2517 u32 len;
2518 u32 name_len;
2519 u64 parent = 0;
2520 int found = 0;
2521 struct btrfs_root *fs_root = ipath->fs_root;
2522 struct btrfs_path *path = ipath->btrfs_path;
2523 struct extent_buffer *eb;
2524 struct btrfs_inode_ref *iref;
2525 struct btrfs_key found_key;
2526
2527 while (!ret) {
2528 ret = btrfs_find_item(fs_root, path, inum,
2529 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2530 &found_key);
2531
2532 if (ret < 0)
2533 break;
2534 if (ret) {
2535 ret = found ? 0 : -ENOENT;
2536 break;
2537 }
2538 ++found;
2539
2540 parent = found_key.offset;
2541 slot = path->slots[0];
2542 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2543 if (!eb) {
2544 ret = -ENOMEM;
2545 break;
2546 }
2547 btrfs_release_path(path);
2548
2549 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2550
2551 for (cur = 0; cur < btrfs_item_size(eb, slot); cur += len) {
2552 name_len = btrfs_inode_ref_name_len(eb, iref);
2553 /* path must be released before calling iterate()! */
2554 btrfs_debug(fs_root->fs_info,
2555 "following ref at offset %u for inode %llu in tree %llu",
2556 cur, found_key.objectid,
2557 fs_root->root_key.objectid);
2558 ret = inode_to_path(parent, name_len,
2559 (unsigned long)(iref + 1), eb, ipath);
2560 if (ret)
2561 break;
2562 len = sizeof(*iref) + name_len;
2563 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2564 }
2565 free_extent_buffer(eb);
2566 }
2567
2568 btrfs_release_path(path);
2569
2570 return ret;
2571}
2572
2573static int iterate_inode_extrefs(u64 inum, struct inode_fs_paths *ipath)
2574{
2575 int ret;
2576 int slot;
2577 u64 offset = 0;
2578 u64 parent;
2579 int found = 0;
2580 struct btrfs_root *fs_root = ipath->fs_root;
2581 struct btrfs_path *path = ipath->btrfs_path;
2582 struct extent_buffer *eb;
2583 struct btrfs_inode_extref *extref;
2584 u32 item_size;
2585 u32 cur_offset;
2586 unsigned long ptr;
2587
2588 while (1) {
2589 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2590 &offset);
2591 if (ret < 0)
2592 break;
2593 if (ret) {
2594 ret = found ? 0 : -ENOENT;
2595 break;
2596 }
2597 ++found;
2598
2599 slot = path->slots[0];
2600 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2601 if (!eb) {
2602 ret = -ENOMEM;
2603 break;
2604 }
2605 btrfs_release_path(path);
2606
2607 item_size = btrfs_item_size(eb, slot);
2608 ptr = btrfs_item_ptr_offset(eb, slot);
2609 cur_offset = 0;
2610
2611 while (cur_offset < item_size) {
2612 u32 name_len;
2613
2614 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2615 parent = btrfs_inode_extref_parent(eb, extref);
2616 name_len = btrfs_inode_extref_name_len(eb, extref);
2617 ret = inode_to_path(parent, name_len,
2618 (unsigned long)&extref->name, eb, ipath);
2619 if (ret)
2620 break;
2621
2622 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2623 cur_offset += sizeof(*extref);
2624 }
2625 free_extent_buffer(eb);
2626
2627 offset++;
2628 }
2629
2630 btrfs_release_path(path);
2631
2632 return ret;
2633}
2634
2635/*
2636 * returns 0 if the path could be dumped (probably truncated)
2637 * returns <0 in case of an error
2638 */
2639static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2640 struct extent_buffer *eb, struct inode_fs_paths *ipath)
2641{
2642 char *fspath;
2643 char *fspath_min;
2644 int i = ipath->fspath->elem_cnt;
2645 const int s_ptr = sizeof(char *);
2646 u32 bytes_left;
2647
2648 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2649 ipath->fspath->bytes_left - s_ptr : 0;
2650
2651 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2652 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2653 name_off, eb, inum, fspath_min, bytes_left);
2654 if (IS_ERR(fspath))
2655 return PTR_ERR(fspath);
2656
2657 if (fspath > fspath_min) {
2658 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2659 ++ipath->fspath->elem_cnt;
2660 ipath->fspath->bytes_left = fspath - fspath_min;
2661 } else {
2662 ++ipath->fspath->elem_missed;
2663 ipath->fspath->bytes_missing += fspath_min - fspath;
2664 ipath->fspath->bytes_left = 0;
2665 }
2666
2667 return 0;
2668}
2669
2670/*
2671 * this dumps all file system paths to the inode into the ipath struct, provided
2672 * is has been created large enough. each path is zero-terminated and accessed
2673 * from ipath->fspath->val[i].
2674 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2675 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2676 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2677 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2678 * have been needed to return all paths.
2679 */
2680int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2681{
2682 int ret;
2683 int found_refs = 0;
2684
2685 ret = iterate_inode_refs(inum, ipath);
2686 if (!ret)
2687 ++found_refs;
2688 else if (ret != -ENOENT)
2689 return ret;
2690
2691 ret = iterate_inode_extrefs(inum, ipath);
2692 if (ret == -ENOENT && found_refs)
2693 return 0;
2694
2695 return ret;
2696}
2697
2698struct btrfs_data_container *init_data_container(u32 total_bytes)
2699{
2700 struct btrfs_data_container *data;
2701 size_t alloc_bytes;
2702
2703 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2704 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2705 if (!data)
2706 return ERR_PTR(-ENOMEM);
2707
2708 if (total_bytes >= sizeof(*data)) {
2709 data->bytes_left = total_bytes - sizeof(*data);
2710 data->bytes_missing = 0;
2711 } else {
2712 data->bytes_missing = sizeof(*data) - total_bytes;
2713 data->bytes_left = 0;
2714 }
2715
2716 data->elem_cnt = 0;
2717 data->elem_missed = 0;
2718
2719 return data;
2720}
2721
2722/*
2723 * allocates space to return multiple file system paths for an inode.
2724 * total_bytes to allocate are passed, note that space usable for actual path
2725 * information will be total_bytes - sizeof(struct inode_fs_paths).
2726 * the returned pointer must be freed with free_ipath() in the end.
2727 */
2728struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2729 struct btrfs_path *path)
2730{
2731 struct inode_fs_paths *ifp;
2732 struct btrfs_data_container *fspath;
2733
2734 fspath = init_data_container(total_bytes);
2735 if (IS_ERR(fspath))
2736 return ERR_CAST(fspath);
2737
2738 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2739 if (!ifp) {
2740 kvfree(fspath);
2741 return ERR_PTR(-ENOMEM);
2742 }
2743
2744 ifp->btrfs_path = path;
2745 ifp->fspath = fspath;
2746 ifp->fs_root = fs_root;
2747
2748 return ifp;
2749}
2750
2751void free_ipath(struct inode_fs_paths *ipath)
2752{
2753 if (!ipath)
2754 return;
2755 kvfree(ipath->fspath);
2756 kfree(ipath);
2757}
2758
2759struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info)
2760{
2761 struct btrfs_backref_iter *ret;
2762
2763 ret = kzalloc(sizeof(*ret), GFP_NOFS);
2764 if (!ret)
2765 return NULL;
2766
2767 ret->path = btrfs_alloc_path();
2768 if (!ret->path) {
2769 kfree(ret);
2770 return NULL;
2771 }
2772
2773 /* Current backref iterator only supports iteration in commit root */
2774 ret->path->search_commit_root = 1;
2775 ret->path->skip_locking = 1;
2776 ret->fs_info = fs_info;
2777
2778 return ret;
2779}
2780
2781int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr)
2782{
2783 struct btrfs_fs_info *fs_info = iter->fs_info;
2784 struct btrfs_root *extent_root = btrfs_extent_root(fs_info, bytenr);
2785 struct btrfs_path *path = iter->path;
2786 struct btrfs_extent_item *ei;
2787 struct btrfs_key key;
2788 int ret;
2789
2790 key.objectid = bytenr;
2791 key.type = BTRFS_METADATA_ITEM_KEY;
2792 key.offset = (u64)-1;
2793 iter->bytenr = bytenr;
2794
2795 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
2796 if (ret < 0)
2797 return ret;
2798 if (ret == 0) {
2799 ret = -EUCLEAN;
2800 goto release;
2801 }
2802 if (path->slots[0] == 0) {
2803 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
2804 ret = -EUCLEAN;
2805 goto release;
2806 }
2807 path->slots[0]--;
2808
2809 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
2810 if ((key.type != BTRFS_EXTENT_ITEM_KEY &&
2811 key.type != BTRFS_METADATA_ITEM_KEY) || key.objectid != bytenr) {
2812 ret = -ENOENT;
2813 goto release;
2814 }
2815 memcpy(&iter->cur_key, &key, sizeof(key));
2816 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2817 path->slots[0]);
2818 iter->end_ptr = (u32)(iter->item_ptr +
2819 btrfs_item_size(path->nodes[0], path->slots[0]));
2820 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
2821 struct btrfs_extent_item);
2822
2823 /*
2824 * Only support iteration on tree backref yet.
2825 *
2826 * This is an extra precaution for non skinny-metadata, where
2827 * EXTENT_ITEM is also used for tree blocks, that we can only use
2828 * extent flags to determine if it's a tree block.
2829 */
2830 if (btrfs_extent_flags(path->nodes[0], ei) & BTRFS_EXTENT_FLAG_DATA) {
2831 ret = -ENOTSUPP;
2832 goto release;
2833 }
2834 iter->cur_ptr = (u32)(iter->item_ptr + sizeof(*ei));
2835
2836 /* If there is no inline backref, go search for keyed backref */
2837 if (iter->cur_ptr >= iter->end_ptr) {
2838 ret = btrfs_next_item(extent_root, path);
2839
2840 /* No inline nor keyed ref */
2841 if (ret > 0) {
2842 ret = -ENOENT;
2843 goto release;
2844 }
2845 if (ret < 0)
2846 goto release;
2847
2848 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key,
2849 path->slots[0]);
2850 if (iter->cur_key.objectid != bytenr ||
2851 (iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY &&
2852 iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY)) {
2853 ret = -ENOENT;
2854 goto release;
2855 }
2856 iter->cur_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2857 path->slots[0]);
2858 iter->item_ptr = iter->cur_ptr;
2859 iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size(
2860 path->nodes[0], path->slots[0]));
2861 }
2862
2863 return 0;
2864release:
2865 btrfs_backref_iter_release(iter);
2866 return ret;
2867}
2868
2869/*
2870 * Go to the next backref item of current bytenr, can be either inlined or
2871 * keyed.
2872 *
2873 * Caller needs to check whether it's inline ref or not by iter->cur_key.
2874 *
2875 * Return 0 if we get next backref without problem.
2876 * Return >0 if there is no extra backref for this bytenr.
2877 * Return <0 if there is something wrong happened.
2878 */
2879int btrfs_backref_iter_next(struct btrfs_backref_iter *iter)
2880{
2881 struct extent_buffer *eb = btrfs_backref_get_eb(iter);
2882 struct btrfs_root *extent_root;
2883 struct btrfs_path *path = iter->path;
2884 struct btrfs_extent_inline_ref *iref;
2885 int ret;
2886 u32 size;
2887
2888 if (btrfs_backref_iter_is_inline_ref(iter)) {
2889 /* We're still inside the inline refs */
2890 ASSERT(iter->cur_ptr < iter->end_ptr);
2891
2892 if (btrfs_backref_has_tree_block_info(iter)) {
2893 /* First tree block info */
2894 size = sizeof(struct btrfs_tree_block_info);
2895 } else {
2896 /* Use inline ref type to determine the size */
2897 int type;
2898
2899 iref = (struct btrfs_extent_inline_ref *)
2900 ((unsigned long)iter->cur_ptr);
2901 type = btrfs_extent_inline_ref_type(eb, iref);
2902
2903 size = btrfs_extent_inline_ref_size(type);
2904 }
2905 iter->cur_ptr += size;
2906 if (iter->cur_ptr < iter->end_ptr)
2907 return 0;
2908
2909 /* All inline items iterated, fall through */
2910 }
2911
2912 /* We're at keyed items, there is no inline item, go to the next one */
2913 extent_root = btrfs_extent_root(iter->fs_info, iter->bytenr);
2914 ret = btrfs_next_item(extent_root, iter->path);
2915 if (ret)
2916 return ret;
2917
2918 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]);
2919 if (iter->cur_key.objectid != iter->bytenr ||
2920 (iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY &&
2921 iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY))
2922 return 1;
2923 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2924 path->slots[0]);
2925 iter->cur_ptr = iter->item_ptr;
2926 iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size(path->nodes[0],
2927 path->slots[0]);
2928 return 0;
2929}
2930
2931void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
2932 struct btrfs_backref_cache *cache, int is_reloc)
2933{
2934 int i;
2935
2936 cache->rb_root = RB_ROOT;
2937 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
2938 INIT_LIST_HEAD(&cache->pending[i]);
2939 INIT_LIST_HEAD(&cache->changed);
2940 INIT_LIST_HEAD(&cache->detached);
2941 INIT_LIST_HEAD(&cache->leaves);
2942 INIT_LIST_HEAD(&cache->pending_edge);
2943 INIT_LIST_HEAD(&cache->useless_node);
2944 cache->fs_info = fs_info;
2945 cache->is_reloc = is_reloc;
2946}
2947
2948struct btrfs_backref_node *btrfs_backref_alloc_node(
2949 struct btrfs_backref_cache *cache, u64 bytenr, int level)
2950{
2951 struct btrfs_backref_node *node;
2952
2953 ASSERT(level >= 0 && level < BTRFS_MAX_LEVEL);
2954 node = kzalloc(sizeof(*node), GFP_NOFS);
2955 if (!node)
2956 return node;
2957
2958 INIT_LIST_HEAD(&node->list);
2959 INIT_LIST_HEAD(&node->upper);
2960 INIT_LIST_HEAD(&node->lower);
2961 RB_CLEAR_NODE(&node->rb_node);
2962 cache->nr_nodes++;
2963 node->level = level;
2964 node->bytenr = bytenr;
2965
2966 return node;
2967}
2968
2969struct btrfs_backref_edge *btrfs_backref_alloc_edge(
2970 struct btrfs_backref_cache *cache)
2971{
2972 struct btrfs_backref_edge *edge;
2973
2974 edge = kzalloc(sizeof(*edge), GFP_NOFS);
2975 if (edge)
2976 cache->nr_edges++;
2977 return edge;
2978}
2979
2980/*
2981 * Drop the backref node from cache, also cleaning up all its
2982 * upper edges and any uncached nodes in the path.
2983 *
2984 * This cleanup happens bottom up, thus the node should either
2985 * be the lowest node in the cache or a detached node.
2986 */
2987void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
2988 struct btrfs_backref_node *node)
2989{
2990 struct btrfs_backref_node *upper;
2991 struct btrfs_backref_edge *edge;
2992
2993 if (!node)
2994 return;
2995
2996 BUG_ON(!node->lowest && !node->detached);
2997 while (!list_empty(&node->upper)) {
2998 edge = list_entry(node->upper.next, struct btrfs_backref_edge,
2999 list[LOWER]);
3000 upper = edge->node[UPPER];
3001 list_del(&edge->list[LOWER]);
3002 list_del(&edge->list[UPPER]);
3003 btrfs_backref_free_edge(cache, edge);
3004
3005 /*
3006 * Add the node to leaf node list if no other child block
3007 * cached.
3008 */
3009 if (list_empty(&upper->lower)) {
3010 list_add_tail(&upper->lower, &cache->leaves);
3011 upper->lowest = 1;
3012 }
3013 }
3014
3015 btrfs_backref_drop_node(cache, node);
3016}
3017
3018/*
3019 * Release all nodes/edges from current cache
3020 */
3021void btrfs_backref_release_cache(struct btrfs_backref_cache *cache)
3022{
3023 struct btrfs_backref_node *node;
3024 int i;
3025
3026 while (!list_empty(&cache->detached)) {
3027 node = list_entry(cache->detached.next,
3028 struct btrfs_backref_node, list);
3029 btrfs_backref_cleanup_node(cache, node);
3030 }
3031
3032 while (!list_empty(&cache->leaves)) {
3033 node = list_entry(cache->leaves.next,
3034 struct btrfs_backref_node, lower);
3035 btrfs_backref_cleanup_node(cache, node);
3036 }
3037
3038 cache->last_trans = 0;
3039
3040 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
3041 ASSERT(list_empty(&cache->pending[i]));
3042 ASSERT(list_empty(&cache->pending_edge));
3043 ASSERT(list_empty(&cache->useless_node));
3044 ASSERT(list_empty(&cache->changed));
3045 ASSERT(list_empty(&cache->detached));
3046 ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
3047 ASSERT(!cache->nr_nodes);
3048 ASSERT(!cache->nr_edges);
3049}
3050
3051/*
3052 * Handle direct tree backref
3053 *
3054 * Direct tree backref means, the backref item shows its parent bytenr
3055 * directly. This is for SHARED_BLOCK_REF backref (keyed or inlined).
3056 *
3057 * @ref_key: The converted backref key.
3058 * For keyed backref, it's the item key.
3059 * For inlined backref, objectid is the bytenr,
3060 * type is btrfs_inline_ref_type, offset is
3061 * btrfs_inline_ref_offset.
3062 */
3063static int handle_direct_tree_backref(struct btrfs_backref_cache *cache,
3064 struct btrfs_key *ref_key,
3065 struct btrfs_backref_node *cur)
3066{
3067 struct btrfs_backref_edge *edge;
3068 struct btrfs_backref_node *upper;
3069 struct rb_node *rb_node;
3070
3071 ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY);
3072
3073 /* Only reloc root uses backref pointing to itself */
3074 if (ref_key->objectid == ref_key->offset) {
3075 struct btrfs_root *root;
3076
3077 cur->is_reloc_root = 1;
3078 /* Only reloc backref cache cares about a specific root */
3079 if (cache->is_reloc) {
3080 root = find_reloc_root(cache->fs_info, cur->bytenr);
3081 if (!root)
3082 return -ENOENT;
3083 cur->root = root;
3084 } else {
3085 /*
3086 * For generic purpose backref cache, reloc root node
3087 * is useless.
3088 */
3089 list_add(&cur->list, &cache->useless_node);
3090 }
3091 return 0;
3092 }
3093
3094 edge = btrfs_backref_alloc_edge(cache);
3095 if (!edge)
3096 return -ENOMEM;
3097
3098 rb_node = rb_simple_search(&cache->rb_root, ref_key->offset);
3099 if (!rb_node) {
3100 /* Parent node not yet cached */
3101 upper = btrfs_backref_alloc_node(cache, ref_key->offset,
3102 cur->level + 1);
3103 if (!upper) {
3104 btrfs_backref_free_edge(cache, edge);
3105 return -ENOMEM;
3106 }
3107
3108 /*
3109 * Backrefs for the upper level block isn't cached, add the
3110 * block to pending list
3111 */
3112 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
3113 } else {
3114 /* Parent node already cached */
3115 upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
3116 ASSERT(upper->checked);
3117 INIT_LIST_HEAD(&edge->list[UPPER]);
3118 }
3119 btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER);
3120 return 0;
3121}
3122
3123/*
3124 * Handle indirect tree backref
3125 *
3126 * Indirect tree backref means, we only know which tree the node belongs to.
3127 * We still need to do a tree search to find out the parents. This is for
3128 * TREE_BLOCK_REF backref (keyed or inlined).
3129 *
3130 * @ref_key: The same as @ref_key in handle_direct_tree_backref()
3131 * @tree_key: The first key of this tree block.
3132 * @path: A clean (released) path, to avoid allocating path every time
3133 * the function get called.
3134 */
3135static int handle_indirect_tree_backref(struct btrfs_backref_cache *cache,
3136 struct btrfs_path *path,
3137 struct btrfs_key *ref_key,
3138 struct btrfs_key *tree_key,
3139 struct btrfs_backref_node *cur)
3140{
3141 struct btrfs_fs_info *fs_info = cache->fs_info;
3142 struct btrfs_backref_node *upper;
3143 struct btrfs_backref_node *lower;
3144 struct btrfs_backref_edge *edge;
3145 struct extent_buffer *eb;
3146 struct btrfs_root *root;
3147 struct rb_node *rb_node;
3148 int level;
3149 bool need_check = true;
3150 int ret;
3151
3152 root = btrfs_get_fs_root(fs_info, ref_key->offset, false);
3153 if (IS_ERR(root))
3154 return PTR_ERR(root);
3155 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
3156 cur->cowonly = 1;
3157
3158 if (btrfs_root_level(&root->root_item) == cur->level) {
3159 /* Tree root */
3160 ASSERT(btrfs_root_bytenr(&root->root_item) == cur->bytenr);
3161 /*
3162 * For reloc backref cache, we may ignore reloc root. But for
3163 * general purpose backref cache, we can't rely on
3164 * btrfs_should_ignore_reloc_root() as it may conflict with
3165 * current running relocation and lead to missing root.
3166 *
3167 * For general purpose backref cache, reloc root detection is
3168 * completely relying on direct backref (key->offset is parent
3169 * bytenr), thus only do such check for reloc cache.
3170 */
3171 if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) {
3172 btrfs_put_root(root);
3173 list_add(&cur->list, &cache->useless_node);
3174 } else {
3175 cur->root = root;
3176 }
3177 return 0;
3178 }
3179
3180 level = cur->level + 1;
3181
3182 /* Search the tree to find parent blocks referring to the block */
3183 path->search_commit_root = 1;
3184 path->skip_locking = 1;
3185 path->lowest_level = level;
3186 ret = btrfs_search_slot(NULL, root, tree_key, path, 0, 0);
3187 path->lowest_level = 0;
3188 if (ret < 0) {
3189 btrfs_put_root(root);
3190 return ret;
3191 }
3192 if (ret > 0 && path->slots[level] > 0)
3193 path->slots[level]--;
3194
3195 eb = path->nodes[level];
3196 if (btrfs_node_blockptr(eb, path->slots[level]) != cur->bytenr) {
3197 btrfs_err(fs_info,
3198"couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
3199 cur->bytenr, level - 1, root->root_key.objectid,
3200 tree_key->objectid, tree_key->type, tree_key->offset);
3201 btrfs_put_root(root);
3202 ret = -ENOENT;
3203 goto out;
3204 }
3205 lower = cur;
3206
3207 /* Add all nodes and edges in the path */
3208 for (; level < BTRFS_MAX_LEVEL; level++) {
3209 if (!path->nodes[level]) {
3210 ASSERT(btrfs_root_bytenr(&root->root_item) ==
3211 lower->bytenr);
3212 /* Same as previous should_ignore_reloc_root() call */
3213 if (btrfs_should_ignore_reloc_root(root) &&
3214 cache->is_reloc) {
3215 btrfs_put_root(root);
3216 list_add(&lower->list, &cache->useless_node);
3217 } else {
3218 lower->root = root;
3219 }
3220 break;
3221 }
3222
3223 edge = btrfs_backref_alloc_edge(cache);
3224 if (!edge) {
3225 btrfs_put_root(root);
3226 ret = -ENOMEM;
3227 goto out;
3228 }
3229
3230 eb = path->nodes[level];
3231 rb_node = rb_simple_search(&cache->rb_root, eb->start);
3232 if (!rb_node) {
3233 upper = btrfs_backref_alloc_node(cache, eb->start,
3234 lower->level + 1);
3235 if (!upper) {
3236 btrfs_put_root(root);
3237 btrfs_backref_free_edge(cache, edge);
3238 ret = -ENOMEM;
3239 goto out;
3240 }
3241 upper->owner = btrfs_header_owner(eb);
3242 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
3243 upper->cowonly = 1;
3244
3245 /*
3246 * If we know the block isn't shared we can avoid
3247 * checking its backrefs.
3248 */
3249 if (btrfs_block_can_be_shared(root, eb))
3250 upper->checked = 0;
3251 else
3252 upper->checked = 1;
3253
3254 /*
3255 * Add the block to pending list if we need to check its
3256 * backrefs, we only do this once while walking up a
3257 * tree as we will catch anything else later on.
3258 */
3259 if (!upper->checked && need_check) {
3260 need_check = false;
3261 list_add_tail(&edge->list[UPPER],
3262 &cache->pending_edge);
3263 } else {
3264 if (upper->checked)
3265 need_check = true;
3266 INIT_LIST_HEAD(&edge->list[UPPER]);
3267 }
3268 } else {
3269 upper = rb_entry(rb_node, struct btrfs_backref_node,
3270 rb_node);
3271 ASSERT(upper->checked);
3272 INIT_LIST_HEAD(&edge->list[UPPER]);
3273 if (!upper->owner)
3274 upper->owner = btrfs_header_owner(eb);
3275 }
3276 btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER);
3277
3278 if (rb_node) {
3279 btrfs_put_root(root);
3280 break;
3281 }
3282 lower = upper;
3283 upper = NULL;
3284 }
3285out:
3286 btrfs_release_path(path);
3287 return ret;
3288}
3289
3290/*
3291 * Add backref node @cur into @cache.
3292 *
3293 * NOTE: Even if the function returned 0, @cur is not yet cached as its upper
3294 * links aren't yet bi-directional. Needs to finish such links.
3295 * Use btrfs_backref_finish_upper_links() to finish such linkage.
3296 *
3297 * @path: Released path for indirect tree backref lookup
3298 * @iter: Released backref iter for extent tree search
3299 * @node_key: The first key of the tree block
3300 */
3301int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
3302 struct btrfs_path *path,
3303 struct btrfs_backref_iter *iter,
3304 struct btrfs_key *node_key,
3305 struct btrfs_backref_node *cur)
3306{
3307 struct btrfs_fs_info *fs_info = cache->fs_info;
3308 struct btrfs_backref_edge *edge;
3309 struct btrfs_backref_node *exist;
3310 int ret;
3311
3312 ret = btrfs_backref_iter_start(iter, cur->bytenr);
3313 if (ret < 0)
3314 return ret;
3315 /*
3316 * We skip the first btrfs_tree_block_info, as we don't use the key
3317 * stored in it, but fetch it from the tree block
3318 */
3319 if (btrfs_backref_has_tree_block_info(iter)) {
3320 ret = btrfs_backref_iter_next(iter);
3321 if (ret < 0)
3322 goto out;
3323 /* No extra backref? This means the tree block is corrupted */
3324 if (ret > 0) {
3325 ret = -EUCLEAN;
3326 goto out;
3327 }
3328 }
3329 WARN_ON(cur->checked);
3330 if (!list_empty(&cur->upper)) {
3331 /*
3332 * The backref was added previously when processing backref of
3333 * type BTRFS_TREE_BLOCK_REF_KEY
3334 */
3335 ASSERT(list_is_singular(&cur->upper));
3336 edge = list_entry(cur->upper.next, struct btrfs_backref_edge,
3337 list[LOWER]);
3338 ASSERT(list_empty(&edge->list[UPPER]));
3339 exist = edge->node[UPPER];
3340 /*
3341 * Add the upper level block to pending list if we need check
3342 * its backrefs
3343 */
3344 if (!exist->checked)
3345 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
3346 } else {
3347 exist = NULL;
3348 }
3349
3350 for (; ret == 0; ret = btrfs_backref_iter_next(iter)) {
3351 struct extent_buffer *eb;
3352 struct btrfs_key key;
3353 int type;
3354
3355 cond_resched();
3356 eb = btrfs_backref_get_eb(iter);
3357
3358 key.objectid = iter->bytenr;
3359 if (btrfs_backref_iter_is_inline_ref(iter)) {
3360 struct btrfs_extent_inline_ref *iref;
3361
3362 /* Update key for inline backref */
3363 iref = (struct btrfs_extent_inline_ref *)
3364 ((unsigned long)iter->cur_ptr);
3365 type = btrfs_get_extent_inline_ref_type(eb, iref,
3366 BTRFS_REF_TYPE_BLOCK);
3367 if (type == BTRFS_REF_TYPE_INVALID) {
3368 ret = -EUCLEAN;
3369 goto out;
3370 }
3371 key.type = type;
3372 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3373 } else {
3374 key.type = iter->cur_key.type;
3375 key.offset = iter->cur_key.offset;
3376 }
3377
3378 /*
3379 * Parent node found and matches current inline ref, no need to
3380 * rebuild this node for this inline ref
3381 */
3382 if (exist &&
3383 ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
3384 exist->owner == key.offset) ||
3385 (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
3386 exist->bytenr == key.offset))) {
3387 exist = NULL;
3388 continue;
3389 }
3390
3391 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */
3392 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
3393 ret = handle_direct_tree_backref(cache, &key, cur);
3394 if (ret < 0)
3395 goto out;
3396 continue;
3397 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
3398 ret = -EINVAL;
3399 btrfs_print_v0_err(fs_info);
3400 btrfs_handle_fs_error(fs_info, ret, NULL);
3401 goto out;
3402 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
3403 continue;
3404 }
3405
3406 /*
3407 * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset
3408 * means the root objectid. We need to search the tree to get
3409 * its parent bytenr.
3410 */
3411 ret = handle_indirect_tree_backref(cache, path, &key, node_key,
3412 cur);
3413 if (ret < 0)
3414 goto out;
3415 }
3416 ret = 0;
3417 cur->checked = 1;
3418 WARN_ON(exist);
3419out:
3420 btrfs_backref_iter_release(iter);
3421 return ret;
3422}
3423
3424/*
3425 * Finish the upwards linkage created by btrfs_backref_add_tree_node()
3426 */
3427int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
3428 struct btrfs_backref_node *start)
3429{
3430 struct list_head *useless_node = &cache->useless_node;
3431 struct btrfs_backref_edge *edge;
3432 struct rb_node *rb_node;
3433 LIST_HEAD(pending_edge);
3434
3435 ASSERT(start->checked);
3436
3437 /* Insert this node to cache if it's not COW-only */
3438 if (!start->cowonly) {
3439 rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
3440 &start->rb_node);
3441 if (rb_node)
3442 btrfs_backref_panic(cache->fs_info, start->bytenr,
3443 -EEXIST);
3444 list_add_tail(&start->lower, &cache->leaves);
3445 }
3446
3447 /*
3448 * Use breadth first search to iterate all related edges.
3449 *
3450 * The starting points are all the edges of this node
3451 */
3452 list_for_each_entry(edge, &start->upper, list[LOWER])
3453 list_add_tail(&edge->list[UPPER], &pending_edge);
3454
3455 while (!list_empty(&pending_edge)) {
3456 struct btrfs_backref_node *upper;
3457 struct btrfs_backref_node *lower;
3458
3459 edge = list_first_entry(&pending_edge,
3460 struct btrfs_backref_edge, list[UPPER]);
3461 list_del_init(&edge->list[UPPER]);
3462 upper = edge->node[UPPER];
3463 lower = edge->node[LOWER];
3464
3465 /* Parent is detached, no need to keep any edges */
3466 if (upper->detached) {
3467 list_del(&edge->list[LOWER]);
3468 btrfs_backref_free_edge(cache, edge);
3469
3470 /* Lower node is orphan, queue for cleanup */
3471 if (list_empty(&lower->upper))
3472 list_add(&lower->list, useless_node);
3473 continue;
3474 }
3475
3476 /*
3477 * All new nodes added in current build_backref_tree() haven't
3478 * been linked to the cache rb tree.
3479 * So if we have upper->rb_node populated, this means a cache
3480 * hit. We only need to link the edge, as @upper and all its
3481 * parents have already been linked.
3482 */
3483 if (!RB_EMPTY_NODE(&upper->rb_node)) {
3484 if (upper->lowest) {
3485 list_del_init(&upper->lower);
3486 upper->lowest = 0;
3487 }
3488
3489 list_add_tail(&edge->list[UPPER], &upper->lower);
3490 continue;
3491 }
3492
3493 /* Sanity check, we shouldn't have any unchecked nodes */
3494 if (!upper->checked) {
3495 ASSERT(0);
3496 return -EUCLEAN;
3497 }
3498
3499 /* Sanity check, COW-only node has non-COW-only parent */
3500 if (start->cowonly != upper->cowonly) {
3501 ASSERT(0);
3502 return -EUCLEAN;
3503 }
3504
3505 /* Only cache non-COW-only (subvolume trees) tree blocks */
3506 if (!upper->cowonly) {
3507 rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
3508 &upper->rb_node);
3509 if (rb_node) {
3510 btrfs_backref_panic(cache->fs_info,
3511 upper->bytenr, -EEXIST);
3512 return -EUCLEAN;
3513 }
3514 }
3515
3516 list_add_tail(&edge->list[UPPER], &upper->lower);
3517
3518 /*
3519 * Also queue all the parent edges of this uncached node
3520 * to finish the upper linkage
3521 */
3522 list_for_each_entry(edge, &upper->upper, list[LOWER])
3523 list_add_tail(&edge->list[UPPER], &pending_edge);
3524 }
3525 return 0;
3526}
3527
3528void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
3529 struct btrfs_backref_node *node)
3530{
3531 struct btrfs_backref_node *lower;
3532 struct btrfs_backref_node *upper;
3533 struct btrfs_backref_edge *edge;
3534
3535 while (!list_empty(&cache->useless_node)) {
3536 lower = list_first_entry(&cache->useless_node,
3537 struct btrfs_backref_node, list);
3538 list_del_init(&lower->list);
3539 }
3540 while (!list_empty(&cache->pending_edge)) {
3541 edge = list_first_entry(&cache->pending_edge,
3542 struct btrfs_backref_edge, list[UPPER]);
3543 list_del(&edge->list[UPPER]);
3544 list_del(&edge->list[LOWER]);
3545 lower = edge->node[LOWER];
3546 upper = edge->node[UPPER];
3547 btrfs_backref_free_edge(cache, edge);
3548
3549 /*
3550 * Lower is no longer linked to any upper backref nodes and
3551 * isn't in the cache, we can free it ourselves.
3552 */
3553 if (list_empty(&lower->upper) &&
3554 RB_EMPTY_NODE(&lower->rb_node))
3555 list_add(&lower->list, &cache->useless_node);
3556
3557 if (!RB_EMPTY_NODE(&upper->rb_node))
3558 continue;
3559
3560 /* Add this guy's upper edges to the list to process */
3561 list_for_each_entry(edge, &upper->upper, list[LOWER])
3562 list_add_tail(&edge->list[UPPER],
3563 &cache->pending_edge);
3564 if (list_empty(&upper->upper))
3565 list_add(&upper->list, &cache->useless_node);
3566 }
3567
3568 while (!list_empty(&cache->useless_node)) {
3569 lower = list_first_entry(&cache->useless_node,
3570 struct btrfs_backref_node, list);
3571 list_del_init(&lower->list);
3572 if (lower == node)
3573 node = NULL;
3574 btrfs_backref_drop_node(cache, lower);
3575 }
3576
3577 btrfs_backref_cleanup_node(cache, node);
3578 ASSERT(list_empty(&cache->useless_node) &&
3579 list_empty(&cache->pending_edge));
3580}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2011 STRATO. All rights reserved.
4 */
5
6#include <linux/mm.h>
7#include <linux/rbtree.h>
8#include <trace/events/btrfs.h>
9#include "ctree.h"
10#include "disk-io.h"
11#include "backref.h"
12#include "ulist.h"
13#include "transaction.h"
14#include "delayed-ref.h"
15#include "locking.h"
16#include "misc.h"
17#include "tree-mod-log.h"
18
19/* Just an arbitrary number so we can be sure this happened */
20#define BACKREF_FOUND_SHARED 6
21
22struct extent_inode_elem {
23 u64 inum;
24 u64 offset;
25 struct extent_inode_elem *next;
26};
27
28static int check_extent_in_eb(const struct btrfs_key *key,
29 const struct extent_buffer *eb,
30 const struct btrfs_file_extent_item *fi,
31 u64 extent_item_pos,
32 struct extent_inode_elem **eie,
33 bool ignore_offset)
34{
35 u64 offset = 0;
36 struct extent_inode_elem *e;
37
38 if (!ignore_offset &&
39 !btrfs_file_extent_compression(eb, fi) &&
40 !btrfs_file_extent_encryption(eb, fi) &&
41 !btrfs_file_extent_other_encoding(eb, fi)) {
42 u64 data_offset;
43 u64 data_len;
44
45 data_offset = btrfs_file_extent_offset(eb, fi);
46 data_len = btrfs_file_extent_num_bytes(eb, fi);
47
48 if (extent_item_pos < data_offset ||
49 extent_item_pos >= data_offset + data_len)
50 return 1;
51 offset = extent_item_pos - data_offset;
52 }
53
54 e = kmalloc(sizeof(*e), GFP_NOFS);
55 if (!e)
56 return -ENOMEM;
57
58 e->next = *eie;
59 e->inum = key->objectid;
60 e->offset = key->offset + offset;
61 *eie = e;
62
63 return 0;
64}
65
66static void free_inode_elem_list(struct extent_inode_elem *eie)
67{
68 struct extent_inode_elem *eie_next;
69
70 for (; eie; eie = eie_next) {
71 eie_next = eie->next;
72 kfree(eie);
73 }
74}
75
76static int find_extent_in_eb(const struct extent_buffer *eb,
77 u64 wanted_disk_byte, u64 extent_item_pos,
78 struct extent_inode_elem **eie,
79 bool ignore_offset)
80{
81 u64 disk_byte;
82 struct btrfs_key key;
83 struct btrfs_file_extent_item *fi;
84 int slot;
85 int nritems;
86 int extent_type;
87 int ret;
88
89 /*
90 * from the shared data ref, we only have the leaf but we need
91 * the key. thus, we must look into all items and see that we
92 * find one (some) with a reference to our extent item.
93 */
94 nritems = btrfs_header_nritems(eb);
95 for (slot = 0; slot < nritems; ++slot) {
96 btrfs_item_key_to_cpu(eb, &key, slot);
97 if (key.type != BTRFS_EXTENT_DATA_KEY)
98 continue;
99 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
100 extent_type = btrfs_file_extent_type(eb, fi);
101 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
102 continue;
103 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
104 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
105 if (disk_byte != wanted_disk_byte)
106 continue;
107
108 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie, ignore_offset);
109 if (ret < 0)
110 return ret;
111 }
112
113 return 0;
114}
115
116struct preftree {
117 struct rb_root_cached root;
118 unsigned int count;
119};
120
121#define PREFTREE_INIT { .root = RB_ROOT_CACHED, .count = 0 }
122
123struct preftrees {
124 struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */
125 struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */
126 struct preftree indirect_missing_keys;
127};
128
129/*
130 * Checks for a shared extent during backref search.
131 *
132 * The share_count tracks prelim_refs (direct and indirect) having a
133 * ref->count >0:
134 * - incremented when a ref->count transitions to >0
135 * - decremented when a ref->count transitions to <1
136 */
137struct share_check {
138 u64 root_objectid;
139 u64 inum;
140 int share_count;
141};
142
143static inline int extent_is_shared(struct share_check *sc)
144{
145 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
146}
147
148static struct kmem_cache *btrfs_prelim_ref_cache;
149
150int __init btrfs_prelim_ref_init(void)
151{
152 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
153 sizeof(struct prelim_ref),
154 0,
155 SLAB_MEM_SPREAD,
156 NULL);
157 if (!btrfs_prelim_ref_cache)
158 return -ENOMEM;
159 return 0;
160}
161
162void __cold btrfs_prelim_ref_exit(void)
163{
164 kmem_cache_destroy(btrfs_prelim_ref_cache);
165}
166
167static void free_pref(struct prelim_ref *ref)
168{
169 kmem_cache_free(btrfs_prelim_ref_cache, ref);
170}
171
172/*
173 * Return 0 when both refs are for the same block (and can be merged).
174 * A -1 return indicates ref1 is a 'lower' block than ref2, while 1
175 * indicates a 'higher' block.
176 */
177static int prelim_ref_compare(struct prelim_ref *ref1,
178 struct prelim_ref *ref2)
179{
180 if (ref1->level < ref2->level)
181 return -1;
182 if (ref1->level > ref2->level)
183 return 1;
184 if (ref1->root_id < ref2->root_id)
185 return -1;
186 if (ref1->root_id > ref2->root_id)
187 return 1;
188 if (ref1->key_for_search.type < ref2->key_for_search.type)
189 return -1;
190 if (ref1->key_for_search.type > ref2->key_for_search.type)
191 return 1;
192 if (ref1->key_for_search.objectid < ref2->key_for_search.objectid)
193 return -1;
194 if (ref1->key_for_search.objectid > ref2->key_for_search.objectid)
195 return 1;
196 if (ref1->key_for_search.offset < ref2->key_for_search.offset)
197 return -1;
198 if (ref1->key_for_search.offset > ref2->key_for_search.offset)
199 return 1;
200 if (ref1->parent < ref2->parent)
201 return -1;
202 if (ref1->parent > ref2->parent)
203 return 1;
204
205 return 0;
206}
207
208static void update_share_count(struct share_check *sc, int oldcount,
209 int newcount)
210{
211 if ((!sc) || (oldcount == 0 && newcount < 1))
212 return;
213
214 if (oldcount > 0 && newcount < 1)
215 sc->share_count--;
216 else if (oldcount < 1 && newcount > 0)
217 sc->share_count++;
218}
219
220/*
221 * Add @newref to the @root rbtree, merging identical refs.
222 *
223 * Callers should assume that newref has been freed after calling.
224 */
225static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
226 struct preftree *preftree,
227 struct prelim_ref *newref,
228 struct share_check *sc)
229{
230 struct rb_root_cached *root;
231 struct rb_node **p;
232 struct rb_node *parent = NULL;
233 struct prelim_ref *ref;
234 int result;
235 bool leftmost = true;
236
237 root = &preftree->root;
238 p = &root->rb_root.rb_node;
239
240 while (*p) {
241 parent = *p;
242 ref = rb_entry(parent, struct prelim_ref, rbnode);
243 result = prelim_ref_compare(ref, newref);
244 if (result < 0) {
245 p = &(*p)->rb_left;
246 } else if (result > 0) {
247 p = &(*p)->rb_right;
248 leftmost = false;
249 } else {
250 /* Identical refs, merge them and free @newref */
251 struct extent_inode_elem *eie = ref->inode_list;
252
253 while (eie && eie->next)
254 eie = eie->next;
255
256 if (!eie)
257 ref->inode_list = newref->inode_list;
258 else
259 eie->next = newref->inode_list;
260 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
261 preftree->count);
262 /*
263 * A delayed ref can have newref->count < 0.
264 * The ref->count is updated to follow any
265 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
266 */
267 update_share_count(sc, ref->count,
268 ref->count + newref->count);
269 ref->count += newref->count;
270 free_pref(newref);
271 return;
272 }
273 }
274
275 update_share_count(sc, 0, newref->count);
276 preftree->count++;
277 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
278 rb_link_node(&newref->rbnode, parent, p);
279 rb_insert_color_cached(&newref->rbnode, root, leftmost);
280}
281
282/*
283 * Release the entire tree. We don't care about internal consistency so
284 * just free everything and then reset the tree root.
285 */
286static void prelim_release(struct preftree *preftree)
287{
288 struct prelim_ref *ref, *next_ref;
289
290 rbtree_postorder_for_each_entry_safe(ref, next_ref,
291 &preftree->root.rb_root, rbnode)
292 free_pref(ref);
293
294 preftree->root = RB_ROOT_CACHED;
295 preftree->count = 0;
296}
297
298/*
299 * the rules for all callers of this function are:
300 * - obtaining the parent is the goal
301 * - if you add a key, you must know that it is a correct key
302 * - if you cannot add the parent or a correct key, then we will look into the
303 * block later to set a correct key
304 *
305 * delayed refs
306 * ============
307 * backref type | shared | indirect | shared | indirect
308 * information | tree | tree | data | data
309 * --------------------+--------+----------+--------+----------
310 * parent logical | y | - | - | -
311 * key to resolve | - | y | y | y
312 * tree block logical | - | - | - | -
313 * root for resolving | y | y | y | y
314 *
315 * - column 1: we've the parent -> done
316 * - column 2, 3, 4: we use the key to find the parent
317 *
318 * on disk refs (inline or keyed)
319 * ==============================
320 * backref type | shared | indirect | shared | indirect
321 * information | tree | tree | data | data
322 * --------------------+--------+----------+--------+----------
323 * parent logical | y | - | y | -
324 * key to resolve | - | - | - | y
325 * tree block logical | y | y | y | y
326 * root for resolving | - | y | y | y
327 *
328 * - column 1, 3: we've the parent -> done
329 * - column 2: we take the first key from the block to find the parent
330 * (see add_missing_keys)
331 * - column 4: we use the key to find the parent
332 *
333 * additional information that's available but not required to find the parent
334 * block might help in merging entries to gain some speed.
335 */
336static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
337 struct preftree *preftree, u64 root_id,
338 const struct btrfs_key *key, int level, u64 parent,
339 u64 wanted_disk_byte, int count,
340 struct share_check *sc, gfp_t gfp_mask)
341{
342 struct prelim_ref *ref;
343
344 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
345 return 0;
346
347 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
348 if (!ref)
349 return -ENOMEM;
350
351 ref->root_id = root_id;
352 if (key)
353 ref->key_for_search = *key;
354 else
355 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
356
357 ref->inode_list = NULL;
358 ref->level = level;
359 ref->count = count;
360 ref->parent = parent;
361 ref->wanted_disk_byte = wanted_disk_byte;
362 prelim_ref_insert(fs_info, preftree, ref, sc);
363 return extent_is_shared(sc);
364}
365
366/* direct refs use root == 0, key == NULL */
367static int add_direct_ref(const struct btrfs_fs_info *fs_info,
368 struct preftrees *preftrees, int level, u64 parent,
369 u64 wanted_disk_byte, int count,
370 struct share_check *sc, gfp_t gfp_mask)
371{
372 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
373 parent, wanted_disk_byte, count, sc, gfp_mask);
374}
375
376/* indirect refs use parent == 0 */
377static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
378 struct preftrees *preftrees, u64 root_id,
379 const struct btrfs_key *key, int level,
380 u64 wanted_disk_byte, int count,
381 struct share_check *sc, gfp_t gfp_mask)
382{
383 struct preftree *tree = &preftrees->indirect;
384
385 if (!key)
386 tree = &preftrees->indirect_missing_keys;
387 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
388 wanted_disk_byte, count, sc, gfp_mask);
389}
390
391static int is_shared_data_backref(struct preftrees *preftrees, u64 bytenr)
392{
393 struct rb_node **p = &preftrees->direct.root.rb_root.rb_node;
394 struct rb_node *parent = NULL;
395 struct prelim_ref *ref = NULL;
396 struct prelim_ref target = {};
397 int result;
398
399 target.parent = bytenr;
400
401 while (*p) {
402 parent = *p;
403 ref = rb_entry(parent, struct prelim_ref, rbnode);
404 result = prelim_ref_compare(ref, &target);
405
406 if (result < 0)
407 p = &(*p)->rb_left;
408 else if (result > 0)
409 p = &(*p)->rb_right;
410 else
411 return 1;
412 }
413 return 0;
414}
415
416static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
417 struct ulist *parents,
418 struct preftrees *preftrees, struct prelim_ref *ref,
419 int level, u64 time_seq, const u64 *extent_item_pos,
420 bool ignore_offset)
421{
422 int ret = 0;
423 int slot;
424 struct extent_buffer *eb;
425 struct btrfs_key key;
426 struct btrfs_key *key_for_search = &ref->key_for_search;
427 struct btrfs_file_extent_item *fi;
428 struct extent_inode_elem *eie = NULL, *old = NULL;
429 u64 disk_byte;
430 u64 wanted_disk_byte = ref->wanted_disk_byte;
431 u64 count = 0;
432 u64 data_offset;
433
434 if (level != 0) {
435 eb = path->nodes[level];
436 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
437 if (ret < 0)
438 return ret;
439 return 0;
440 }
441
442 /*
443 * 1. We normally enter this function with the path already pointing to
444 * the first item to check. But sometimes, we may enter it with
445 * slot == nritems.
446 * 2. We are searching for normal backref but bytenr of this leaf
447 * matches shared data backref
448 * 3. The leaf owner is not equal to the root we are searching
449 *
450 * For these cases, go to the next leaf before we continue.
451 */
452 eb = path->nodes[0];
453 if (path->slots[0] >= btrfs_header_nritems(eb) ||
454 is_shared_data_backref(preftrees, eb->start) ||
455 ref->root_id != btrfs_header_owner(eb)) {
456 if (time_seq == BTRFS_SEQ_LAST)
457 ret = btrfs_next_leaf(root, path);
458 else
459 ret = btrfs_next_old_leaf(root, path, time_seq);
460 }
461
462 while (!ret && count < ref->count) {
463 eb = path->nodes[0];
464 slot = path->slots[0];
465
466 btrfs_item_key_to_cpu(eb, &key, slot);
467
468 if (key.objectid != key_for_search->objectid ||
469 key.type != BTRFS_EXTENT_DATA_KEY)
470 break;
471
472 /*
473 * We are searching for normal backref but bytenr of this leaf
474 * matches shared data backref, OR
475 * the leaf owner is not equal to the root we are searching for
476 */
477 if (slot == 0 &&
478 (is_shared_data_backref(preftrees, eb->start) ||
479 ref->root_id != btrfs_header_owner(eb))) {
480 if (time_seq == BTRFS_SEQ_LAST)
481 ret = btrfs_next_leaf(root, path);
482 else
483 ret = btrfs_next_old_leaf(root, path, time_seq);
484 continue;
485 }
486 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
487 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
488 data_offset = btrfs_file_extent_offset(eb, fi);
489
490 if (disk_byte == wanted_disk_byte) {
491 eie = NULL;
492 old = NULL;
493 if (ref->key_for_search.offset == key.offset - data_offset)
494 count++;
495 else
496 goto next;
497 if (extent_item_pos) {
498 ret = check_extent_in_eb(&key, eb, fi,
499 *extent_item_pos,
500 &eie, ignore_offset);
501 if (ret < 0)
502 break;
503 }
504 if (ret > 0)
505 goto next;
506 ret = ulist_add_merge_ptr(parents, eb->start,
507 eie, (void **)&old, GFP_NOFS);
508 if (ret < 0)
509 break;
510 if (!ret && extent_item_pos) {
511 while (old->next)
512 old = old->next;
513 old->next = eie;
514 }
515 eie = NULL;
516 }
517next:
518 if (time_seq == BTRFS_SEQ_LAST)
519 ret = btrfs_next_item(root, path);
520 else
521 ret = btrfs_next_old_item(root, path, time_seq);
522 }
523
524 if (ret > 0)
525 ret = 0;
526 else if (ret < 0)
527 free_inode_elem_list(eie);
528 return ret;
529}
530
531/*
532 * resolve an indirect backref in the form (root_id, key, level)
533 * to a logical address
534 */
535static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
536 struct btrfs_path *path, u64 time_seq,
537 struct preftrees *preftrees,
538 struct prelim_ref *ref, struct ulist *parents,
539 const u64 *extent_item_pos, bool ignore_offset)
540{
541 struct btrfs_root *root;
542 struct extent_buffer *eb;
543 int ret = 0;
544 int root_level;
545 int level = ref->level;
546 struct btrfs_key search_key = ref->key_for_search;
547
548 /*
549 * If we're search_commit_root we could possibly be holding locks on
550 * other tree nodes. This happens when qgroups does backref walks when
551 * adding new delayed refs. To deal with this we need to look in cache
552 * for the root, and if we don't find it then we need to search the
553 * tree_root's commit root, thus the btrfs_get_fs_root_commit_root usage
554 * here.
555 */
556 if (path->search_commit_root)
557 root = btrfs_get_fs_root_commit_root(fs_info, path, ref->root_id);
558 else
559 root = btrfs_get_fs_root(fs_info, ref->root_id, false);
560 if (IS_ERR(root)) {
561 ret = PTR_ERR(root);
562 goto out_free;
563 }
564
565 if (!path->search_commit_root &&
566 test_bit(BTRFS_ROOT_DELETING, &root->state)) {
567 ret = -ENOENT;
568 goto out;
569 }
570
571 if (btrfs_is_testing(fs_info)) {
572 ret = -ENOENT;
573 goto out;
574 }
575
576 if (path->search_commit_root)
577 root_level = btrfs_header_level(root->commit_root);
578 else if (time_seq == BTRFS_SEQ_LAST)
579 root_level = btrfs_header_level(root->node);
580 else
581 root_level = btrfs_old_root_level(root, time_seq);
582
583 if (root_level + 1 == level)
584 goto out;
585
586 /*
587 * We can often find data backrefs with an offset that is too large
588 * (>= LLONG_MAX, maximum allowed file offset) due to underflows when
589 * subtracting a file's offset with the data offset of its
590 * corresponding extent data item. This can happen for example in the
591 * clone ioctl.
592 *
593 * So if we detect such case we set the search key's offset to zero to
594 * make sure we will find the matching file extent item at
595 * add_all_parents(), otherwise we will miss it because the offset
596 * taken form the backref is much larger then the offset of the file
597 * extent item. This can make us scan a very large number of file
598 * extent items, but at least it will not make us miss any.
599 *
600 * This is an ugly workaround for a behaviour that should have never
601 * existed, but it does and a fix for the clone ioctl would touch a lot
602 * of places, cause backwards incompatibility and would not fix the
603 * problem for extents cloned with older kernels.
604 */
605 if (search_key.type == BTRFS_EXTENT_DATA_KEY &&
606 search_key.offset >= LLONG_MAX)
607 search_key.offset = 0;
608 path->lowest_level = level;
609 if (time_seq == BTRFS_SEQ_LAST)
610 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
611 else
612 ret = btrfs_search_old_slot(root, &search_key, path, time_seq);
613
614 btrfs_debug(fs_info,
615 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
616 ref->root_id, level, ref->count, ret,
617 ref->key_for_search.objectid, ref->key_for_search.type,
618 ref->key_for_search.offset);
619 if (ret < 0)
620 goto out;
621
622 eb = path->nodes[level];
623 while (!eb) {
624 if (WARN_ON(!level)) {
625 ret = 1;
626 goto out;
627 }
628 level--;
629 eb = path->nodes[level];
630 }
631
632 ret = add_all_parents(root, path, parents, preftrees, ref, level,
633 time_seq, extent_item_pos, ignore_offset);
634out:
635 btrfs_put_root(root);
636out_free:
637 path->lowest_level = 0;
638 btrfs_release_path(path);
639 return ret;
640}
641
642static struct extent_inode_elem *
643unode_aux_to_inode_list(struct ulist_node *node)
644{
645 if (!node)
646 return NULL;
647 return (struct extent_inode_elem *)(uintptr_t)node->aux;
648}
649
650/*
651 * We maintain three separate rbtrees: one for direct refs, one for
652 * indirect refs which have a key, and one for indirect refs which do not
653 * have a key. Each tree does merge on insertion.
654 *
655 * Once all of the references are located, we iterate over the tree of
656 * indirect refs with missing keys. An appropriate key is located and
657 * the ref is moved onto the tree for indirect refs. After all missing
658 * keys are thus located, we iterate over the indirect ref tree, resolve
659 * each reference, and then insert the resolved reference onto the
660 * direct tree (merging there too).
661 *
662 * New backrefs (i.e., for parent nodes) are added to the appropriate
663 * rbtree as they are encountered. The new backrefs are subsequently
664 * resolved as above.
665 */
666static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
667 struct btrfs_path *path, u64 time_seq,
668 struct preftrees *preftrees,
669 const u64 *extent_item_pos,
670 struct share_check *sc, bool ignore_offset)
671{
672 int err;
673 int ret = 0;
674 struct ulist *parents;
675 struct ulist_node *node;
676 struct ulist_iterator uiter;
677 struct rb_node *rnode;
678
679 parents = ulist_alloc(GFP_NOFS);
680 if (!parents)
681 return -ENOMEM;
682
683 /*
684 * We could trade memory usage for performance here by iterating
685 * the tree, allocating new refs for each insertion, and then
686 * freeing the entire indirect tree when we're done. In some test
687 * cases, the tree can grow quite large (~200k objects).
688 */
689 while ((rnode = rb_first_cached(&preftrees->indirect.root))) {
690 struct prelim_ref *ref;
691
692 ref = rb_entry(rnode, struct prelim_ref, rbnode);
693 if (WARN(ref->parent,
694 "BUG: direct ref found in indirect tree")) {
695 ret = -EINVAL;
696 goto out;
697 }
698
699 rb_erase_cached(&ref->rbnode, &preftrees->indirect.root);
700 preftrees->indirect.count--;
701
702 if (ref->count == 0) {
703 free_pref(ref);
704 continue;
705 }
706
707 if (sc && sc->root_objectid &&
708 ref->root_id != sc->root_objectid) {
709 free_pref(ref);
710 ret = BACKREF_FOUND_SHARED;
711 goto out;
712 }
713 err = resolve_indirect_ref(fs_info, path, time_seq, preftrees,
714 ref, parents, extent_item_pos,
715 ignore_offset);
716 /*
717 * we can only tolerate ENOENT,otherwise,we should catch error
718 * and return directly.
719 */
720 if (err == -ENOENT) {
721 prelim_ref_insert(fs_info, &preftrees->direct, ref,
722 NULL);
723 continue;
724 } else if (err) {
725 free_pref(ref);
726 ret = err;
727 goto out;
728 }
729
730 /* we put the first parent into the ref at hand */
731 ULIST_ITER_INIT(&uiter);
732 node = ulist_next(parents, &uiter);
733 ref->parent = node ? node->val : 0;
734 ref->inode_list = unode_aux_to_inode_list(node);
735
736 /* Add a prelim_ref(s) for any other parent(s). */
737 while ((node = ulist_next(parents, &uiter))) {
738 struct prelim_ref *new_ref;
739
740 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
741 GFP_NOFS);
742 if (!new_ref) {
743 free_pref(ref);
744 ret = -ENOMEM;
745 goto out;
746 }
747 memcpy(new_ref, ref, sizeof(*ref));
748 new_ref->parent = node->val;
749 new_ref->inode_list = unode_aux_to_inode_list(node);
750 prelim_ref_insert(fs_info, &preftrees->direct,
751 new_ref, NULL);
752 }
753
754 /*
755 * Now it's a direct ref, put it in the direct tree. We must
756 * do this last because the ref could be merged/freed here.
757 */
758 prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL);
759
760 ulist_reinit(parents);
761 cond_resched();
762 }
763out:
764 ulist_free(parents);
765 return ret;
766}
767
768/*
769 * read tree blocks and add keys where required.
770 */
771static int add_missing_keys(struct btrfs_fs_info *fs_info,
772 struct preftrees *preftrees, bool lock)
773{
774 struct prelim_ref *ref;
775 struct extent_buffer *eb;
776 struct preftree *tree = &preftrees->indirect_missing_keys;
777 struct rb_node *node;
778
779 while ((node = rb_first_cached(&tree->root))) {
780 ref = rb_entry(node, struct prelim_ref, rbnode);
781 rb_erase_cached(node, &tree->root);
782
783 BUG_ON(ref->parent); /* should not be a direct ref */
784 BUG_ON(ref->key_for_search.type);
785 BUG_ON(!ref->wanted_disk_byte);
786
787 eb = read_tree_block(fs_info, ref->wanted_disk_byte,
788 ref->root_id, 0, ref->level - 1, NULL);
789 if (IS_ERR(eb)) {
790 free_pref(ref);
791 return PTR_ERR(eb);
792 } else if (!extent_buffer_uptodate(eb)) {
793 free_pref(ref);
794 free_extent_buffer(eb);
795 return -EIO;
796 }
797 if (lock)
798 btrfs_tree_read_lock(eb);
799 if (btrfs_header_level(eb) == 0)
800 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
801 else
802 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
803 if (lock)
804 btrfs_tree_read_unlock(eb);
805 free_extent_buffer(eb);
806 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
807 cond_resched();
808 }
809 return 0;
810}
811
812/*
813 * add all currently queued delayed refs from this head whose seq nr is
814 * smaller or equal that seq to the list
815 */
816static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
817 struct btrfs_delayed_ref_head *head, u64 seq,
818 struct preftrees *preftrees, struct share_check *sc)
819{
820 struct btrfs_delayed_ref_node *node;
821 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
822 struct btrfs_key key;
823 struct btrfs_key tmp_op_key;
824 struct rb_node *n;
825 int count;
826 int ret = 0;
827
828 if (extent_op && extent_op->update_key)
829 btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
830
831 spin_lock(&head->lock);
832 for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
833 node = rb_entry(n, struct btrfs_delayed_ref_node,
834 ref_node);
835 if (node->seq > seq)
836 continue;
837
838 switch (node->action) {
839 case BTRFS_ADD_DELAYED_EXTENT:
840 case BTRFS_UPDATE_DELAYED_HEAD:
841 WARN_ON(1);
842 continue;
843 case BTRFS_ADD_DELAYED_REF:
844 count = node->ref_mod;
845 break;
846 case BTRFS_DROP_DELAYED_REF:
847 count = node->ref_mod * -1;
848 break;
849 default:
850 BUG();
851 }
852 switch (node->type) {
853 case BTRFS_TREE_BLOCK_REF_KEY: {
854 /* NORMAL INDIRECT METADATA backref */
855 struct btrfs_delayed_tree_ref *ref;
856
857 ref = btrfs_delayed_node_to_tree_ref(node);
858 ret = add_indirect_ref(fs_info, preftrees, ref->root,
859 &tmp_op_key, ref->level + 1,
860 node->bytenr, count, sc,
861 GFP_ATOMIC);
862 break;
863 }
864 case BTRFS_SHARED_BLOCK_REF_KEY: {
865 /* SHARED DIRECT METADATA backref */
866 struct btrfs_delayed_tree_ref *ref;
867
868 ref = btrfs_delayed_node_to_tree_ref(node);
869
870 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
871 ref->parent, node->bytenr, count,
872 sc, GFP_ATOMIC);
873 break;
874 }
875 case BTRFS_EXTENT_DATA_REF_KEY: {
876 /* NORMAL INDIRECT DATA backref */
877 struct btrfs_delayed_data_ref *ref;
878 ref = btrfs_delayed_node_to_data_ref(node);
879
880 key.objectid = ref->objectid;
881 key.type = BTRFS_EXTENT_DATA_KEY;
882 key.offset = ref->offset;
883
884 /*
885 * Found a inum that doesn't match our known inum, we
886 * know it's shared.
887 */
888 if (sc && sc->inum && ref->objectid != sc->inum) {
889 ret = BACKREF_FOUND_SHARED;
890 goto out;
891 }
892
893 ret = add_indirect_ref(fs_info, preftrees, ref->root,
894 &key, 0, node->bytenr, count, sc,
895 GFP_ATOMIC);
896 break;
897 }
898 case BTRFS_SHARED_DATA_REF_KEY: {
899 /* SHARED DIRECT FULL backref */
900 struct btrfs_delayed_data_ref *ref;
901
902 ref = btrfs_delayed_node_to_data_ref(node);
903
904 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
905 node->bytenr, count, sc,
906 GFP_ATOMIC);
907 break;
908 }
909 default:
910 WARN_ON(1);
911 }
912 /*
913 * We must ignore BACKREF_FOUND_SHARED until all delayed
914 * refs have been checked.
915 */
916 if (ret && (ret != BACKREF_FOUND_SHARED))
917 break;
918 }
919 if (!ret)
920 ret = extent_is_shared(sc);
921out:
922 spin_unlock(&head->lock);
923 return ret;
924}
925
926/*
927 * add all inline backrefs for bytenr to the list
928 *
929 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
930 */
931static int add_inline_refs(const struct btrfs_fs_info *fs_info,
932 struct btrfs_path *path, u64 bytenr,
933 int *info_level, struct preftrees *preftrees,
934 struct share_check *sc)
935{
936 int ret = 0;
937 int slot;
938 struct extent_buffer *leaf;
939 struct btrfs_key key;
940 struct btrfs_key found_key;
941 unsigned long ptr;
942 unsigned long end;
943 struct btrfs_extent_item *ei;
944 u64 flags;
945 u64 item_size;
946
947 /*
948 * enumerate all inline refs
949 */
950 leaf = path->nodes[0];
951 slot = path->slots[0];
952
953 item_size = btrfs_item_size_nr(leaf, slot);
954 BUG_ON(item_size < sizeof(*ei));
955
956 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
957 flags = btrfs_extent_flags(leaf, ei);
958 btrfs_item_key_to_cpu(leaf, &found_key, slot);
959
960 ptr = (unsigned long)(ei + 1);
961 end = (unsigned long)ei + item_size;
962
963 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
964 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
965 struct btrfs_tree_block_info *info;
966
967 info = (struct btrfs_tree_block_info *)ptr;
968 *info_level = btrfs_tree_block_level(leaf, info);
969 ptr += sizeof(struct btrfs_tree_block_info);
970 BUG_ON(ptr > end);
971 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
972 *info_level = found_key.offset;
973 } else {
974 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
975 }
976
977 while (ptr < end) {
978 struct btrfs_extent_inline_ref *iref;
979 u64 offset;
980 int type;
981
982 iref = (struct btrfs_extent_inline_ref *)ptr;
983 type = btrfs_get_extent_inline_ref_type(leaf, iref,
984 BTRFS_REF_TYPE_ANY);
985 if (type == BTRFS_REF_TYPE_INVALID)
986 return -EUCLEAN;
987
988 offset = btrfs_extent_inline_ref_offset(leaf, iref);
989
990 switch (type) {
991 case BTRFS_SHARED_BLOCK_REF_KEY:
992 ret = add_direct_ref(fs_info, preftrees,
993 *info_level + 1, offset,
994 bytenr, 1, NULL, GFP_NOFS);
995 break;
996 case BTRFS_SHARED_DATA_REF_KEY: {
997 struct btrfs_shared_data_ref *sdref;
998 int count;
999
1000 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
1001 count = btrfs_shared_data_ref_count(leaf, sdref);
1002
1003 ret = add_direct_ref(fs_info, preftrees, 0, offset,
1004 bytenr, count, sc, GFP_NOFS);
1005 break;
1006 }
1007 case BTRFS_TREE_BLOCK_REF_KEY:
1008 ret = add_indirect_ref(fs_info, preftrees, offset,
1009 NULL, *info_level + 1,
1010 bytenr, 1, NULL, GFP_NOFS);
1011 break;
1012 case BTRFS_EXTENT_DATA_REF_KEY: {
1013 struct btrfs_extent_data_ref *dref;
1014 int count;
1015 u64 root;
1016
1017 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1018 count = btrfs_extent_data_ref_count(leaf, dref);
1019 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1020 dref);
1021 key.type = BTRFS_EXTENT_DATA_KEY;
1022 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1023
1024 if (sc && sc->inum && key.objectid != sc->inum) {
1025 ret = BACKREF_FOUND_SHARED;
1026 break;
1027 }
1028
1029 root = btrfs_extent_data_ref_root(leaf, dref);
1030
1031 ret = add_indirect_ref(fs_info, preftrees, root,
1032 &key, 0, bytenr, count,
1033 sc, GFP_NOFS);
1034 break;
1035 }
1036 default:
1037 WARN_ON(1);
1038 }
1039 if (ret)
1040 return ret;
1041 ptr += btrfs_extent_inline_ref_size(type);
1042 }
1043
1044 return 0;
1045}
1046
1047/*
1048 * add all non-inline backrefs for bytenr to the list
1049 *
1050 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
1051 */
1052static int add_keyed_refs(struct btrfs_fs_info *fs_info,
1053 struct btrfs_path *path, u64 bytenr,
1054 int info_level, struct preftrees *preftrees,
1055 struct share_check *sc)
1056{
1057 struct btrfs_root *extent_root = fs_info->extent_root;
1058 int ret;
1059 int slot;
1060 struct extent_buffer *leaf;
1061 struct btrfs_key key;
1062
1063 while (1) {
1064 ret = btrfs_next_item(extent_root, path);
1065 if (ret < 0)
1066 break;
1067 if (ret) {
1068 ret = 0;
1069 break;
1070 }
1071
1072 slot = path->slots[0];
1073 leaf = path->nodes[0];
1074 btrfs_item_key_to_cpu(leaf, &key, slot);
1075
1076 if (key.objectid != bytenr)
1077 break;
1078 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1079 continue;
1080 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1081 break;
1082
1083 switch (key.type) {
1084 case BTRFS_SHARED_BLOCK_REF_KEY:
1085 /* SHARED DIRECT METADATA backref */
1086 ret = add_direct_ref(fs_info, preftrees,
1087 info_level + 1, key.offset,
1088 bytenr, 1, NULL, GFP_NOFS);
1089 break;
1090 case BTRFS_SHARED_DATA_REF_KEY: {
1091 /* SHARED DIRECT FULL backref */
1092 struct btrfs_shared_data_ref *sdref;
1093 int count;
1094
1095 sdref = btrfs_item_ptr(leaf, slot,
1096 struct btrfs_shared_data_ref);
1097 count = btrfs_shared_data_ref_count(leaf, sdref);
1098 ret = add_direct_ref(fs_info, preftrees, 0,
1099 key.offset, bytenr, count,
1100 sc, GFP_NOFS);
1101 break;
1102 }
1103 case BTRFS_TREE_BLOCK_REF_KEY:
1104 /* NORMAL INDIRECT METADATA backref */
1105 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1106 NULL, info_level + 1, bytenr,
1107 1, NULL, GFP_NOFS);
1108 break;
1109 case BTRFS_EXTENT_DATA_REF_KEY: {
1110 /* NORMAL INDIRECT DATA backref */
1111 struct btrfs_extent_data_ref *dref;
1112 int count;
1113 u64 root;
1114
1115 dref = btrfs_item_ptr(leaf, slot,
1116 struct btrfs_extent_data_ref);
1117 count = btrfs_extent_data_ref_count(leaf, dref);
1118 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1119 dref);
1120 key.type = BTRFS_EXTENT_DATA_KEY;
1121 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1122
1123 if (sc && sc->inum && key.objectid != sc->inum) {
1124 ret = BACKREF_FOUND_SHARED;
1125 break;
1126 }
1127
1128 root = btrfs_extent_data_ref_root(leaf, dref);
1129 ret = add_indirect_ref(fs_info, preftrees, root,
1130 &key, 0, bytenr, count,
1131 sc, GFP_NOFS);
1132 break;
1133 }
1134 default:
1135 WARN_ON(1);
1136 }
1137 if (ret)
1138 return ret;
1139
1140 }
1141
1142 return ret;
1143}
1144
1145/*
1146 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1147 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1148 * indirect refs to their parent bytenr.
1149 * When roots are found, they're added to the roots list
1150 *
1151 * If time_seq is set to BTRFS_SEQ_LAST, it will not search delayed_refs, and
1152 * behave much like trans == NULL case, the difference only lies in it will not
1153 * commit root.
1154 * The special case is for qgroup to search roots in commit_transaction().
1155 *
1156 * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a
1157 * shared extent is detected.
1158 *
1159 * Otherwise this returns 0 for success and <0 for an error.
1160 *
1161 * If ignore_offset is set to false, only extent refs whose offsets match
1162 * extent_item_pos are returned. If true, every extent ref is returned
1163 * and extent_item_pos is ignored.
1164 *
1165 * FIXME some caching might speed things up
1166 */
1167static int find_parent_nodes(struct btrfs_trans_handle *trans,
1168 struct btrfs_fs_info *fs_info, u64 bytenr,
1169 u64 time_seq, struct ulist *refs,
1170 struct ulist *roots, const u64 *extent_item_pos,
1171 struct share_check *sc, bool ignore_offset)
1172{
1173 struct btrfs_key key;
1174 struct btrfs_path *path;
1175 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1176 struct btrfs_delayed_ref_head *head;
1177 int info_level = 0;
1178 int ret;
1179 struct prelim_ref *ref;
1180 struct rb_node *node;
1181 struct extent_inode_elem *eie = NULL;
1182 struct preftrees preftrees = {
1183 .direct = PREFTREE_INIT,
1184 .indirect = PREFTREE_INIT,
1185 .indirect_missing_keys = PREFTREE_INIT
1186 };
1187
1188 key.objectid = bytenr;
1189 key.offset = (u64)-1;
1190 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1191 key.type = BTRFS_METADATA_ITEM_KEY;
1192 else
1193 key.type = BTRFS_EXTENT_ITEM_KEY;
1194
1195 path = btrfs_alloc_path();
1196 if (!path)
1197 return -ENOMEM;
1198 if (!trans) {
1199 path->search_commit_root = 1;
1200 path->skip_locking = 1;
1201 }
1202
1203 if (time_seq == BTRFS_SEQ_LAST)
1204 path->skip_locking = 1;
1205
1206 /*
1207 * grab both a lock on the path and a lock on the delayed ref head.
1208 * We need both to get a consistent picture of how the refs look
1209 * at a specified point in time
1210 */
1211again:
1212 head = NULL;
1213
1214 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
1215 if (ret < 0)
1216 goto out;
1217 BUG_ON(ret == 0);
1218
1219#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1220 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1221 time_seq != BTRFS_SEQ_LAST) {
1222#else
1223 if (trans && time_seq != BTRFS_SEQ_LAST) {
1224#endif
1225 /*
1226 * look if there are updates for this ref queued and lock the
1227 * head
1228 */
1229 delayed_refs = &trans->transaction->delayed_refs;
1230 spin_lock(&delayed_refs->lock);
1231 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
1232 if (head) {
1233 if (!mutex_trylock(&head->mutex)) {
1234 refcount_inc(&head->refs);
1235 spin_unlock(&delayed_refs->lock);
1236
1237 btrfs_release_path(path);
1238
1239 /*
1240 * Mutex was contended, block until it's
1241 * released and try again
1242 */
1243 mutex_lock(&head->mutex);
1244 mutex_unlock(&head->mutex);
1245 btrfs_put_delayed_ref_head(head);
1246 goto again;
1247 }
1248 spin_unlock(&delayed_refs->lock);
1249 ret = add_delayed_refs(fs_info, head, time_seq,
1250 &preftrees, sc);
1251 mutex_unlock(&head->mutex);
1252 if (ret)
1253 goto out;
1254 } else {
1255 spin_unlock(&delayed_refs->lock);
1256 }
1257 }
1258
1259 if (path->slots[0]) {
1260 struct extent_buffer *leaf;
1261 int slot;
1262
1263 path->slots[0]--;
1264 leaf = path->nodes[0];
1265 slot = path->slots[0];
1266 btrfs_item_key_to_cpu(leaf, &key, slot);
1267 if (key.objectid == bytenr &&
1268 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1269 key.type == BTRFS_METADATA_ITEM_KEY)) {
1270 ret = add_inline_refs(fs_info, path, bytenr,
1271 &info_level, &preftrees, sc);
1272 if (ret)
1273 goto out;
1274 ret = add_keyed_refs(fs_info, path, bytenr, info_level,
1275 &preftrees, sc);
1276 if (ret)
1277 goto out;
1278 }
1279 }
1280
1281 btrfs_release_path(path);
1282
1283 ret = add_missing_keys(fs_info, &preftrees, path->skip_locking == 0);
1284 if (ret)
1285 goto out;
1286
1287 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root));
1288
1289 ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees,
1290 extent_item_pos, sc, ignore_offset);
1291 if (ret)
1292 goto out;
1293
1294 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root));
1295
1296 /*
1297 * This walks the tree of merged and resolved refs. Tree blocks are
1298 * read in as needed. Unique entries are added to the ulist, and
1299 * the list of found roots is updated.
1300 *
1301 * We release the entire tree in one go before returning.
1302 */
1303 node = rb_first_cached(&preftrees.direct.root);
1304 while (node) {
1305 ref = rb_entry(node, struct prelim_ref, rbnode);
1306 node = rb_next(&ref->rbnode);
1307 /*
1308 * ref->count < 0 can happen here if there are delayed
1309 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1310 * prelim_ref_insert() relies on this when merging
1311 * identical refs to keep the overall count correct.
1312 * prelim_ref_insert() will merge only those refs
1313 * which compare identically. Any refs having
1314 * e.g. different offsets would not be merged,
1315 * and would retain their original ref->count < 0.
1316 */
1317 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1318 if (sc && sc->root_objectid &&
1319 ref->root_id != sc->root_objectid) {
1320 ret = BACKREF_FOUND_SHARED;
1321 goto out;
1322 }
1323
1324 /* no parent == root of tree */
1325 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1326 if (ret < 0)
1327 goto out;
1328 }
1329 if (ref->count && ref->parent) {
1330 if (extent_item_pos && !ref->inode_list &&
1331 ref->level == 0) {
1332 struct extent_buffer *eb;
1333
1334 eb = read_tree_block(fs_info, ref->parent, 0,
1335 0, ref->level, NULL);
1336 if (IS_ERR(eb)) {
1337 ret = PTR_ERR(eb);
1338 goto out;
1339 } else if (!extent_buffer_uptodate(eb)) {
1340 free_extent_buffer(eb);
1341 ret = -EIO;
1342 goto out;
1343 }
1344
1345 if (!path->skip_locking)
1346 btrfs_tree_read_lock(eb);
1347 ret = find_extent_in_eb(eb, bytenr,
1348 *extent_item_pos, &eie, ignore_offset);
1349 if (!path->skip_locking)
1350 btrfs_tree_read_unlock(eb);
1351 free_extent_buffer(eb);
1352 if (ret < 0)
1353 goto out;
1354 ref->inode_list = eie;
1355 }
1356 ret = ulist_add_merge_ptr(refs, ref->parent,
1357 ref->inode_list,
1358 (void **)&eie, GFP_NOFS);
1359 if (ret < 0)
1360 goto out;
1361 if (!ret && extent_item_pos) {
1362 /*
1363 * we've recorded that parent, so we must extend
1364 * its inode list here
1365 */
1366 BUG_ON(!eie);
1367 while (eie->next)
1368 eie = eie->next;
1369 eie->next = ref->inode_list;
1370 }
1371 eie = NULL;
1372 }
1373 cond_resched();
1374 }
1375
1376out:
1377 btrfs_free_path(path);
1378
1379 prelim_release(&preftrees.direct);
1380 prelim_release(&preftrees.indirect);
1381 prelim_release(&preftrees.indirect_missing_keys);
1382
1383 if (ret < 0)
1384 free_inode_elem_list(eie);
1385 return ret;
1386}
1387
1388static void free_leaf_list(struct ulist *blocks)
1389{
1390 struct ulist_node *node = NULL;
1391 struct extent_inode_elem *eie;
1392 struct ulist_iterator uiter;
1393
1394 ULIST_ITER_INIT(&uiter);
1395 while ((node = ulist_next(blocks, &uiter))) {
1396 if (!node->aux)
1397 continue;
1398 eie = unode_aux_to_inode_list(node);
1399 free_inode_elem_list(eie);
1400 node->aux = 0;
1401 }
1402
1403 ulist_free(blocks);
1404}
1405
1406/*
1407 * Finds all leafs with a reference to the specified combination of bytenr and
1408 * offset. key_list_head will point to a list of corresponding keys (caller must
1409 * free each list element). The leafs will be stored in the leafs ulist, which
1410 * must be freed with ulist_free.
1411 *
1412 * returns 0 on success, <0 on error
1413 */
1414int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1415 struct btrfs_fs_info *fs_info, u64 bytenr,
1416 u64 time_seq, struct ulist **leafs,
1417 const u64 *extent_item_pos, bool ignore_offset)
1418{
1419 int ret;
1420
1421 *leafs = ulist_alloc(GFP_NOFS);
1422 if (!*leafs)
1423 return -ENOMEM;
1424
1425 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1426 *leafs, NULL, extent_item_pos, NULL, ignore_offset);
1427 if (ret < 0 && ret != -ENOENT) {
1428 free_leaf_list(*leafs);
1429 return ret;
1430 }
1431
1432 return 0;
1433}
1434
1435/*
1436 * walk all backrefs for a given extent to find all roots that reference this
1437 * extent. Walking a backref means finding all extents that reference this
1438 * extent and in turn walk the backrefs of those, too. Naturally this is a
1439 * recursive process, but here it is implemented in an iterative fashion: We
1440 * find all referencing extents for the extent in question and put them on a
1441 * list. In turn, we find all referencing extents for those, further appending
1442 * to the list. The way we iterate the list allows adding more elements after
1443 * the current while iterating. The process stops when we reach the end of the
1444 * list. Found roots are added to the roots list.
1445 *
1446 * returns 0 on success, < 0 on error.
1447 */
1448static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
1449 struct btrfs_fs_info *fs_info, u64 bytenr,
1450 u64 time_seq, struct ulist **roots,
1451 bool ignore_offset)
1452{
1453 struct ulist *tmp;
1454 struct ulist_node *node = NULL;
1455 struct ulist_iterator uiter;
1456 int ret;
1457
1458 tmp = ulist_alloc(GFP_NOFS);
1459 if (!tmp)
1460 return -ENOMEM;
1461 *roots = ulist_alloc(GFP_NOFS);
1462 if (!*roots) {
1463 ulist_free(tmp);
1464 return -ENOMEM;
1465 }
1466
1467 ULIST_ITER_INIT(&uiter);
1468 while (1) {
1469 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1470 tmp, *roots, NULL, NULL, ignore_offset);
1471 if (ret < 0 && ret != -ENOENT) {
1472 ulist_free(tmp);
1473 ulist_free(*roots);
1474 *roots = NULL;
1475 return ret;
1476 }
1477 node = ulist_next(tmp, &uiter);
1478 if (!node)
1479 break;
1480 bytenr = node->val;
1481 cond_resched();
1482 }
1483
1484 ulist_free(tmp);
1485 return 0;
1486}
1487
1488int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1489 struct btrfs_fs_info *fs_info, u64 bytenr,
1490 u64 time_seq, struct ulist **roots,
1491 bool ignore_offset, bool skip_commit_root_sem)
1492{
1493 int ret;
1494
1495 if (!trans && !skip_commit_root_sem)
1496 down_read(&fs_info->commit_root_sem);
1497 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr,
1498 time_seq, roots, ignore_offset);
1499 if (!trans && !skip_commit_root_sem)
1500 up_read(&fs_info->commit_root_sem);
1501 return ret;
1502}
1503
1504/**
1505 * Check if an extent is shared or not
1506 *
1507 * @root: root inode belongs to
1508 * @inum: inode number of the inode whose extent we are checking
1509 * @bytenr: logical bytenr of the extent we are checking
1510 * @roots: list of roots this extent is shared among
1511 * @tmp: temporary list used for iteration
1512 *
1513 * btrfs_check_shared uses the backref walking code but will short
1514 * circuit as soon as it finds a root or inode that doesn't match the
1515 * one passed in. This provides a significant performance benefit for
1516 * callers (such as fiemap) which want to know whether the extent is
1517 * shared but do not need a ref count.
1518 *
1519 * This attempts to attach to the running transaction in order to account for
1520 * delayed refs, but continues on even when no running transaction exists.
1521 *
1522 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1523 */
1524int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr,
1525 struct ulist *roots, struct ulist *tmp)
1526{
1527 struct btrfs_fs_info *fs_info = root->fs_info;
1528 struct btrfs_trans_handle *trans;
1529 struct ulist_iterator uiter;
1530 struct ulist_node *node;
1531 struct btrfs_seq_list elem = BTRFS_SEQ_LIST_INIT(elem);
1532 int ret = 0;
1533 struct share_check shared = {
1534 .root_objectid = root->root_key.objectid,
1535 .inum = inum,
1536 .share_count = 0,
1537 };
1538
1539 ulist_init(roots);
1540 ulist_init(tmp);
1541
1542 trans = btrfs_join_transaction_nostart(root);
1543 if (IS_ERR(trans)) {
1544 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
1545 ret = PTR_ERR(trans);
1546 goto out;
1547 }
1548 trans = NULL;
1549 down_read(&fs_info->commit_root_sem);
1550 } else {
1551 btrfs_get_tree_mod_seq(fs_info, &elem);
1552 }
1553
1554 ULIST_ITER_INIT(&uiter);
1555 while (1) {
1556 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1557 roots, NULL, &shared, false);
1558 if (ret == BACKREF_FOUND_SHARED) {
1559 /* this is the only condition under which we return 1 */
1560 ret = 1;
1561 break;
1562 }
1563 if (ret < 0 && ret != -ENOENT)
1564 break;
1565 ret = 0;
1566 node = ulist_next(tmp, &uiter);
1567 if (!node)
1568 break;
1569 bytenr = node->val;
1570 shared.share_count = 0;
1571 cond_resched();
1572 }
1573
1574 if (trans) {
1575 btrfs_put_tree_mod_seq(fs_info, &elem);
1576 btrfs_end_transaction(trans);
1577 } else {
1578 up_read(&fs_info->commit_root_sem);
1579 }
1580out:
1581 ulist_release(roots);
1582 ulist_release(tmp);
1583 return ret;
1584}
1585
1586int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1587 u64 start_off, struct btrfs_path *path,
1588 struct btrfs_inode_extref **ret_extref,
1589 u64 *found_off)
1590{
1591 int ret, slot;
1592 struct btrfs_key key;
1593 struct btrfs_key found_key;
1594 struct btrfs_inode_extref *extref;
1595 const struct extent_buffer *leaf;
1596 unsigned long ptr;
1597
1598 key.objectid = inode_objectid;
1599 key.type = BTRFS_INODE_EXTREF_KEY;
1600 key.offset = start_off;
1601
1602 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1603 if (ret < 0)
1604 return ret;
1605
1606 while (1) {
1607 leaf = path->nodes[0];
1608 slot = path->slots[0];
1609 if (slot >= btrfs_header_nritems(leaf)) {
1610 /*
1611 * If the item at offset is not found,
1612 * btrfs_search_slot will point us to the slot
1613 * where it should be inserted. In our case
1614 * that will be the slot directly before the
1615 * next INODE_REF_KEY_V2 item. In the case
1616 * that we're pointing to the last slot in a
1617 * leaf, we must move one leaf over.
1618 */
1619 ret = btrfs_next_leaf(root, path);
1620 if (ret) {
1621 if (ret >= 1)
1622 ret = -ENOENT;
1623 break;
1624 }
1625 continue;
1626 }
1627
1628 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1629
1630 /*
1631 * Check that we're still looking at an extended ref key for
1632 * this particular objectid. If we have different
1633 * objectid or type then there are no more to be found
1634 * in the tree and we can exit.
1635 */
1636 ret = -ENOENT;
1637 if (found_key.objectid != inode_objectid)
1638 break;
1639 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1640 break;
1641
1642 ret = 0;
1643 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1644 extref = (struct btrfs_inode_extref *)ptr;
1645 *ret_extref = extref;
1646 if (found_off)
1647 *found_off = found_key.offset;
1648 break;
1649 }
1650
1651 return ret;
1652}
1653
1654/*
1655 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1656 * Elements of the path are separated by '/' and the path is guaranteed to be
1657 * 0-terminated. the path is only given within the current file system.
1658 * Therefore, it never starts with a '/'. the caller is responsible to provide
1659 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1660 * the start point of the resulting string is returned. this pointer is within
1661 * dest, normally.
1662 * in case the path buffer would overflow, the pointer is decremented further
1663 * as if output was written to the buffer, though no more output is actually
1664 * generated. that way, the caller can determine how much space would be
1665 * required for the path to fit into the buffer. in that case, the returned
1666 * value will be smaller than dest. callers must check this!
1667 */
1668char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1669 u32 name_len, unsigned long name_off,
1670 struct extent_buffer *eb_in, u64 parent,
1671 char *dest, u32 size)
1672{
1673 int slot;
1674 u64 next_inum;
1675 int ret;
1676 s64 bytes_left = ((s64)size) - 1;
1677 struct extent_buffer *eb = eb_in;
1678 struct btrfs_key found_key;
1679 struct btrfs_inode_ref *iref;
1680
1681 if (bytes_left >= 0)
1682 dest[bytes_left] = '\0';
1683
1684 while (1) {
1685 bytes_left -= name_len;
1686 if (bytes_left >= 0)
1687 read_extent_buffer(eb, dest + bytes_left,
1688 name_off, name_len);
1689 if (eb != eb_in) {
1690 if (!path->skip_locking)
1691 btrfs_tree_read_unlock(eb);
1692 free_extent_buffer(eb);
1693 }
1694 ret = btrfs_find_item(fs_root, path, parent, 0,
1695 BTRFS_INODE_REF_KEY, &found_key);
1696 if (ret > 0)
1697 ret = -ENOENT;
1698 if (ret)
1699 break;
1700
1701 next_inum = found_key.offset;
1702
1703 /* regular exit ahead */
1704 if (parent == next_inum)
1705 break;
1706
1707 slot = path->slots[0];
1708 eb = path->nodes[0];
1709 /* make sure we can use eb after releasing the path */
1710 if (eb != eb_in) {
1711 path->nodes[0] = NULL;
1712 path->locks[0] = 0;
1713 }
1714 btrfs_release_path(path);
1715 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1716
1717 name_len = btrfs_inode_ref_name_len(eb, iref);
1718 name_off = (unsigned long)(iref + 1);
1719
1720 parent = next_inum;
1721 --bytes_left;
1722 if (bytes_left >= 0)
1723 dest[bytes_left] = '/';
1724 }
1725
1726 btrfs_release_path(path);
1727
1728 if (ret)
1729 return ERR_PTR(ret);
1730
1731 return dest + bytes_left;
1732}
1733
1734/*
1735 * this makes the path point to (logical EXTENT_ITEM *)
1736 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1737 * tree blocks and <0 on error.
1738 */
1739int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1740 struct btrfs_path *path, struct btrfs_key *found_key,
1741 u64 *flags_ret)
1742{
1743 int ret;
1744 u64 flags;
1745 u64 size = 0;
1746 u32 item_size;
1747 const struct extent_buffer *eb;
1748 struct btrfs_extent_item *ei;
1749 struct btrfs_key key;
1750
1751 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1752 key.type = BTRFS_METADATA_ITEM_KEY;
1753 else
1754 key.type = BTRFS_EXTENT_ITEM_KEY;
1755 key.objectid = logical;
1756 key.offset = (u64)-1;
1757
1758 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1759 if (ret < 0)
1760 return ret;
1761
1762 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1763 if (ret) {
1764 if (ret > 0)
1765 ret = -ENOENT;
1766 return ret;
1767 }
1768 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1769 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1770 size = fs_info->nodesize;
1771 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1772 size = found_key->offset;
1773
1774 if (found_key->objectid > logical ||
1775 found_key->objectid + size <= logical) {
1776 btrfs_debug(fs_info,
1777 "logical %llu is not within any extent", logical);
1778 return -ENOENT;
1779 }
1780
1781 eb = path->nodes[0];
1782 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1783 BUG_ON(item_size < sizeof(*ei));
1784
1785 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1786 flags = btrfs_extent_flags(eb, ei);
1787
1788 btrfs_debug(fs_info,
1789 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1790 logical, logical - found_key->objectid, found_key->objectid,
1791 found_key->offset, flags, item_size);
1792
1793 WARN_ON(!flags_ret);
1794 if (flags_ret) {
1795 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1796 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1797 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1798 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1799 else
1800 BUG();
1801 return 0;
1802 }
1803
1804 return -EIO;
1805}
1806
1807/*
1808 * helper function to iterate extent inline refs. ptr must point to a 0 value
1809 * for the first call and may be modified. it is used to track state.
1810 * if more refs exist, 0 is returned and the next call to
1811 * get_extent_inline_ref must pass the modified ptr parameter to get the
1812 * next ref. after the last ref was processed, 1 is returned.
1813 * returns <0 on error
1814 */
1815static int get_extent_inline_ref(unsigned long *ptr,
1816 const struct extent_buffer *eb,
1817 const struct btrfs_key *key,
1818 const struct btrfs_extent_item *ei,
1819 u32 item_size,
1820 struct btrfs_extent_inline_ref **out_eiref,
1821 int *out_type)
1822{
1823 unsigned long end;
1824 u64 flags;
1825 struct btrfs_tree_block_info *info;
1826
1827 if (!*ptr) {
1828 /* first call */
1829 flags = btrfs_extent_flags(eb, ei);
1830 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1831 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1832 /* a skinny metadata extent */
1833 *out_eiref =
1834 (struct btrfs_extent_inline_ref *)(ei + 1);
1835 } else {
1836 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1837 info = (struct btrfs_tree_block_info *)(ei + 1);
1838 *out_eiref =
1839 (struct btrfs_extent_inline_ref *)(info + 1);
1840 }
1841 } else {
1842 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1843 }
1844 *ptr = (unsigned long)*out_eiref;
1845 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1846 return -ENOENT;
1847 }
1848
1849 end = (unsigned long)ei + item_size;
1850 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1851 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
1852 BTRFS_REF_TYPE_ANY);
1853 if (*out_type == BTRFS_REF_TYPE_INVALID)
1854 return -EUCLEAN;
1855
1856 *ptr += btrfs_extent_inline_ref_size(*out_type);
1857 WARN_ON(*ptr > end);
1858 if (*ptr == end)
1859 return 1; /* last */
1860
1861 return 0;
1862}
1863
1864/*
1865 * reads the tree block backref for an extent. tree level and root are returned
1866 * through out_level and out_root. ptr must point to a 0 value for the first
1867 * call and may be modified (see get_extent_inline_ref comment).
1868 * returns 0 if data was provided, 1 if there was no more data to provide or
1869 * <0 on error.
1870 */
1871int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1872 struct btrfs_key *key, struct btrfs_extent_item *ei,
1873 u32 item_size, u64 *out_root, u8 *out_level)
1874{
1875 int ret;
1876 int type;
1877 struct btrfs_extent_inline_ref *eiref;
1878
1879 if (*ptr == (unsigned long)-1)
1880 return 1;
1881
1882 while (1) {
1883 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
1884 &eiref, &type);
1885 if (ret < 0)
1886 return ret;
1887
1888 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1889 type == BTRFS_SHARED_BLOCK_REF_KEY)
1890 break;
1891
1892 if (ret == 1)
1893 return 1;
1894 }
1895
1896 /* we can treat both ref types equally here */
1897 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1898
1899 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1900 struct btrfs_tree_block_info *info;
1901
1902 info = (struct btrfs_tree_block_info *)(ei + 1);
1903 *out_level = btrfs_tree_block_level(eb, info);
1904 } else {
1905 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1906 *out_level = (u8)key->offset;
1907 }
1908
1909 if (ret == 1)
1910 *ptr = (unsigned long)-1;
1911
1912 return 0;
1913}
1914
1915static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1916 struct extent_inode_elem *inode_list,
1917 u64 root, u64 extent_item_objectid,
1918 iterate_extent_inodes_t *iterate, void *ctx)
1919{
1920 struct extent_inode_elem *eie;
1921 int ret = 0;
1922
1923 for (eie = inode_list; eie; eie = eie->next) {
1924 btrfs_debug(fs_info,
1925 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1926 extent_item_objectid, eie->inum,
1927 eie->offset, root);
1928 ret = iterate(eie->inum, eie->offset, root, ctx);
1929 if (ret) {
1930 btrfs_debug(fs_info,
1931 "stopping iteration for %llu due to ret=%d",
1932 extent_item_objectid, ret);
1933 break;
1934 }
1935 }
1936
1937 return ret;
1938}
1939
1940/*
1941 * calls iterate() for every inode that references the extent identified by
1942 * the given parameters.
1943 * when the iterator function returns a non-zero value, iteration stops.
1944 */
1945int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1946 u64 extent_item_objectid, u64 extent_item_pos,
1947 int search_commit_root,
1948 iterate_extent_inodes_t *iterate, void *ctx,
1949 bool ignore_offset)
1950{
1951 int ret;
1952 struct btrfs_trans_handle *trans = NULL;
1953 struct ulist *refs = NULL;
1954 struct ulist *roots = NULL;
1955 struct ulist_node *ref_node = NULL;
1956 struct ulist_node *root_node = NULL;
1957 struct btrfs_seq_list seq_elem = BTRFS_SEQ_LIST_INIT(seq_elem);
1958 struct ulist_iterator ref_uiter;
1959 struct ulist_iterator root_uiter;
1960
1961 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
1962 extent_item_objectid);
1963
1964 if (!search_commit_root) {
1965 trans = btrfs_attach_transaction(fs_info->extent_root);
1966 if (IS_ERR(trans)) {
1967 if (PTR_ERR(trans) != -ENOENT &&
1968 PTR_ERR(trans) != -EROFS)
1969 return PTR_ERR(trans);
1970 trans = NULL;
1971 }
1972 }
1973
1974 if (trans)
1975 btrfs_get_tree_mod_seq(fs_info, &seq_elem);
1976 else
1977 down_read(&fs_info->commit_root_sem);
1978
1979 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1980 seq_elem.seq, &refs,
1981 &extent_item_pos, ignore_offset);
1982 if (ret)
1983 goto out;
1984
1985 ULIST_ITER_INIT(&ref_uiter);
1986 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1987 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val,
1988 seq_elem.seq, &roots,
1989 ignore_offset);
1990 if (ret)
1991 break;
1992 ULIST_ITER_INIT(&root_uiter);
1993 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1994 btrfs_debug(fs_info,
1995 "root %llu references leaf %llu, data list %#llx",
1996 root_node->val, ref_node->val,
1997 ref_node->aux);
1998 ret = iterate_leaf_refs(fs_info,
1999 (struct extent_inode_elem *)
2000 (uintptr_t)ref_node->aux,
2001 root_node->val,
2002 extent_item_objectid,
2003 iterate, ctx);
2004 }
2005 ulist_free(roots);
2006 }
2007
2008 free_leaf_list(refs);
2009out:
2010 if (trans) {
2011 btrfs_put_tree_mod_seq(fs_info, &seq_elem);
2012 btrfs_end_transaction(trans);
2013 } else {
2014 up_read(&fs_info->commit_root_sem);
2015 }
2016
2017 return ret;
2018}
2019
2020int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
2021 struct btrfs_path *path,
2022 iterate_extent_inodes_t *iterate, void *ctx,
2023 bool ignore_offset)
2024{
2025 int ret;
2026 u64 extent_item_pos;
2027 u64 flags = 0;
2028 struct btrfs_key found_key;
2029 int search_commit_root = path->search_commit_root;
2030
2031 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
2032 btrfs_release_path(path);
2033 if (ret < 0)
2034 return ret;
2035 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2036 return -EINVAL;
2037
2038 extent_item_pos = logical - found_key.objectid;
2039 ret = iterate_extent_inodes(fs_info, found_key.objectid,
2040 extent_item_pos, search_commit_root,
2041 iterate, ctx, ignore_offset);
2042
2043 return ret;
2044}
2045
2046typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
2047 struct extent_buffer *eb, void *ctx);
2048
2049static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
2050 struct btrfs_path *path,
2051 iterate_irefs_t *iterate, void *ctx)
2052{
2053 int ret = 0;
2054 int slot;
2055 u32 cur;
2056 u32 len;
2057 u32 name_len;
2058 u64 parent = 0;
2059 int found = 0;
2060 struct extent_buffer *eb;
2061 struct btrfs_item *item;
2062 struct btrfs_inode_ref *iref;
2063 struct btrfs_key found_key;
2064
2065 while (!ret) {
2066 ret = btrfs_find_item(fs_root, path, inum,
2067 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2068 &found_key);
2069
2070 if (ret < 0)
2071 break;
2072 if (ret) {
2073 ret = found ? 0 : -ENOENT;
2074 break;
2075 }
2076 ++found;
2077
2078 parent = found_key.offset;
2079 slot = path->slots[0];
2080 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2081 if (!eb) {
2082 ret = -ENOMEM;
2083 break;
2084 }
2085 btrfs_release_path(path);
2086
2087 item = btrfs_item_nr(slot);
2088 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2089
2090 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
2091 name_len = btrfs_inode_ref_name_len(eb, iref);
2092 /* path must be released before calling iterate()! */
2093 btrfs_debug(fs_root->fs_info,
2094 "following ref at offset %u for inode %llu in tree %llu",
2095 cur, found_key.objectid,
2096 fs_root->root_key.objectid);
2097 ret = iterate(parent, name_len,
2098 (unsigned long)(iref + 1), eb, ctx);
2099 if (ret)
2100 break;
2101 len = sizeof(*iref) + name_len;
2102 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2103 }
2104 free_extent_buffer(eb);
2105 }
2106
2107 btrfs_release_path(path);
2108
2109 return ret;
2110}
2111
2112static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
2113 struct btrfs_path *path,
2114 iterate_irefs_t *iterate, void *ctx)
2115{
2116 int ret;
2117 int slot;
2118 u64 offset = 0;
2119 u64 parent;
2120 int found = 0;
2121 struct extent_buffer *eb;
2122 struct btrfs_inode_extref *extref;
2123 u32 item_size;
2124 u32 cur_offset;
2125 unsigned long ptr;
2126
2127 while (1) {
2128 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2129 &offset);
2130 if (ret < 0)
2131 break;
2132 if (ret) {
2133 ret = found ? 0 : -ENOENT;
2134 break;
2135 }
2136 ++found;
2137
2138 slot = path->slots[0];
2139 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2140 if (!eb) {
2141 ret = -ENOMEM;
2142 break;
2143 }
2144 btrfs_release_path(path);
2145
2146 item_size = btrfs_item_size_nr(eb, slot);
2147 ptr = btrfs_item_ptr_offset(eb, slot);
2148 cur_offset = 0;
2149
2150 while (cur_offset < item_size) {
2151 u32 name_len;
2152
2153 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2154 parent = btrfs_inode_extref_parent(eb, extref);
2155 name_len = btrfs_inode_extref_name_len(eb, extref);
2156 ret = iterate(parent, name_len,
2157 (unsigned long)&extref->name, eb, ctx);
2158 if (ret)
2159 break;
2160
2161 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2162 cur_offset += sizeof(*extref);
2163 }
2164 free_extent_buffer(eb);
2165
2166 offset++;
2167 }
2168
2169 btrfs_release_path(path);
2170
2171 return ret;
2172}
2173
2174static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
2175 struct btrfs_path *path, iterate_irefs_t *iterate,
2176 void *ctx)
2177{
2178 int ret;
2179 int found_refs = 0;
2180
2181 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
2182 if (!ret)
2183 ++found_refs;
2184 else if (ret != -ENOENT)
2185 return ret;
2186
2187 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
2188 if (ret == -ENOENT && found_refs)
2189 return 0;
2190
2191 return ret;
2192}
2193
2194/*
2195 * returns 0 if the path could be dumped (probably truncated)
2196 * returns <0 in case of an error
2197 */
2198static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2199 struct extent_buffer *eb, void *ctx)
2200{
2201 struct inode_fs_paths *ipath = ctx;
2202 char *fspath;
2203 char *fspath_min;
2204 int i = ipath->fspath->elem_cnt;
2205 const int s_ptr = sizeof(char *);
2206 u32 bytes_left;
2207
2208 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2209 ipath->fspath->bytes_left - s_ptr : 0;
2210
2211 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2212 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2213 name_off, eb, inum, fspath_min, bytes_left);
2214 if (IS_ERR(fspath))
2215 return PTR_ERR(fspath);
2216
2217 if (fspath > fspath_min) {
2218 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2219 ++ipath->fspath->elem_cnt;
2220 ipath->fspath->bytes_left = fspath - fspath_min;
2221 } else {
2222 ++ipath->fspath->elem_missed;
2223 ipath->fspath->bytes_missing += fspath_min - fspath;
2224 ipath->fspath->bytes_left = 0;
2225 }
2226
2227 return 0;
2228}
2229
2230/*
2231 * this dumps all file system paths to the inode into the ipath struct, provided
2232 * is has been created large enough. each path is zero-terminated and accessed
2233 * from ipath->fspath->val[i].
2234 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2235 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2236 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2237 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2238 * have been needed to return all paths.
2239 */
2240int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2241{
2242 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
2243 inode_to_path, ipath);
2244}
2245
2246struct btrfs_data_container *init_data_container(u32 total_bytes)
2247{
2248 struct btrfs_data_container *data;
2249 size_t alloc_bytes;
2250
2251 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2252 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2253 if (!data)
2254 return ERR_PTR(-ENOMEM);
2255
2256 if (total_bytes >= sizeof(*data)) {
2257 data->bytes_left = total_bytes - sizeof(*data);
2258 data->bytes_missing = 0;
2259 } else {
2260 data->bytes_missing = sizeof(*data) - total_bytes;
2261 data->bytes_left = 0;
2262 }
2263
2264 data->elem_cnt = 0;
2265 data->elem_missed = 0;
2266
2267 return data;
2268}
2269
2270/*
2271 * allocates space to return multiple file system paths for an inode.
2272 * total_bytes to allocate are passed, note that space usable for actual path
2273 * information will be total_bytes - sizeof(struct inode_fs_paths).
2274 * the returned pointer must be freed with free_ipath() in the end.
2275 */
2276struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2277 struct btrfs_path *path)
2278{
2279 struct inode_fs_paths *ifp;
2280 struct btrfs_data_container *fspath;
2281
2282 fspath = init_data_container(total_bytes);
2283 if (IS_ERR(fspath))
2284 return ERR_CAST(fspath);
2285
2286 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2287 if (!ifp) {
2288 kvfree(fspath);
2289 return ERR_PTR(-ENOMEM);
2290 }
2291
2292 ifp->btrfs_path = path;
2293 ifp->fspath = fspath;
2294 ifp->fs_root = fs_root;
2295
2296 return ifp;
2297}
2298
2299void free_ipath(struct inode_fs_paths *ipath)
2300{
2301 if (!ipath)
2302 return;
2303 kvfree(ipath->fspath);
2304 kfree(ipath);
2305}
2306
2307struct btrfs_backref_iter *btrfs_backref_iter_alloc(
2308 struct btrfs_fs_info *fs_info, gfp_t gfp_flag)
2309{
2310 struct btrfs_backref_iter *ret;
2311
2312 ret = kzalloc(sizeof(*ret), gfp_flag);
2313 if (!ret)
2314 return NULL;
2315
2316 ret->path = btrfs_alloc_path();
2317 if (!ret->path) {
2318 kfree(ret);
2319 return NULL;
2320 }
2321
2322 /* Current backref iterator only supports iteration in commit root */
2323 ret->path->search_commit_root = 1;
2324 ret->path->skip_locking = 1;
2325 ret->fs_info = fs_info;
2326
2327 return ret;
2328}
2329
2330int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr)
2331{
2332 struct btrfs_fs_info *fs_info = iter->fs_info;
2333 struct btrfs_path *path = iter->path;
2334 struct btrfs_extent_item *ei;
2335 struct btrfs_key key;
2336 int ret;
2337
2338 key.objectid = bytenr;
2339 key.type = BTRFS_METADATA_ITEM_KEY;
2340 key.offset = (u64)-1;
2341 iter->bytenr = bytenr;
2342
2343 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
2344 if (ret < 0)
2345 return ret;
2346 if (ret == 0) {
2347 ret = -EUCLEAN;
2348 goto release;
2349 }
2350 if (path->slots[0] == 0) {
2351 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
2352 ret = -EUCLEAN;
2353 goto release;
2354 }
2355 path->slots[0]--;
2356
2357 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
2358 if ((key.type != BTRFS_EXTENT_ITEM_KEY &&
2359 key.type != BTRFS_METADATA_ITEM_KEY) || key.objectid != bytenr) {
2360 ret = -ENOENT;
2361 goto release;
2362 }
2363 memcpy(&iter->cur_key, &key, sizeof(key));
2364 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2365 path->slots[0]);
2366 iter->end_ptr = (u32)(iter->item_ptr +
2367 btrfs_item_size_nr(path->nodes[0], path->slots[0]));
2368 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
2369 struct btrfs_extent_item);
2370
2371 /*
2372 * Only support iteration on tree backref yet.
2373 *
2374 * This is an extra precaution for non skinny-metadata, where
2375 * EXTENT_ITEM is also used for tree blocks, that we can only use
2376 * extent flags to determine if it's a tree block.
2377 */
2378 if (btrfs_extent_flags(path->nodes[0], ei) & BTRFS_EXTENT_FLAG_DATA) {
2379 ret = -ENOTSUPP;
2380 goto release;
2381 }
2382 iter->cur_ptr = (u32)(iter->item_ptr + sizeof(*ei));
2383
2384 /* If there is no inline backref, go search for keyed backref */
2385 if (iter->cur_ptr >= iter->end_ptr) {
2386 ret = btrfs_next_item(fs_info->extent_root, path);
2387
2388 /* No inline nor keyed ref */
2389 if (ret > 0) {
2390 ret = -ENOENT;
2391 goto release;
2392 }
2393 if (ret < 0)
2394 goto release;
2395
2396 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key,
2397 path->slots[0]);
2398 if (iter->cur_key.objectid != bytenr ||
2399 (iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY &&
2400 iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY)) {
2401 ret = -ENOENT;
2402 goto release;
2403 }
2404 iter->cur_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2405 path->slots[0]);
2406 iter->item_ptr = iter->cur_ptr;
2407 iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size_nr(
2408 path->nodes[0], path->slots[0]));
2409 }
2410
2411 return 0;
2412release:
2413 btrfs_backref_iter_release(iter);
2414 return ret;
2415}
2416
2417/*
2418 * Go to the next backref item of current bytenr, can be either inlined or
2419 * keyed.
2420 *
2421 * Caller needs to check whether it's inline ref or not by iter->cur_key.
2422 *
2423 * Return 0 if we get next backref without problem.
2424 * Return >0 if there is no extra backref for this bytenr.
2425 * Return <0 if there is something wrong happened.
2426 */
2427int btrfs_backref_iter_next(struct btrfs_backref_iter *iter)
2428{
2429 struct extent_buffer *eb = btrfs_backref_get_eb(iter);
2430 struct btrfs_path *path = iter->path;
2431 struct btrfs_extent_inline_ref *iref;
2432 int ret;
2433 u32 size;
2434
2435 if (btrfs_backref_iter_is_inline_ref(iter)) {
2436 /* We're still inside the inline refs */
2437 ASSERT(iter->cur_ptr < iter->end_ptr);
2438
2439 if (btrfs_backref_has_tree_block_info(iter)) {
2440 /* First tree block info */
2441 size = sizeof(struct btrfs_tree_block_info);
2442 } else {
2443 /* Use inline ref type to determine the size */
2444 int type;
2445
2446 iref = (struct btrfs_extent_inline_ref *)
2447 ((unsigned long)iter->cur_ptr);
2448 type = btrfs_extent_inline_ref_type(eb, iref);
2449
2450 size = btrfs_extent_inline_ref_size(type);
2451 }
2452 iter->cur_ptr += size;
2453 if (iter->cur_ptr < iter->end_ptr)
2454 return 0;
2455
2456 /* All inline items iterated, fall through */
2457 }
2458
2459 /* We're at keyed items, there is no inline item, go to the next one */
2460 ret = btrfs_next_item(iter->fs_info->extent_root, iter->path);
2461 if (ret)
2462 return ret;
2463
2464 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]);
2465 if (iter->cur_key.objectid != iter->bytenr ||
2466 (iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY &&
2467 iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY))
2468 return 1;
2469 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2470 path->slots[0]);
2471 iter->cur_ptr = iter->item_ptr;
2472 iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size_nr(path->nodes[0],
2473 path->slots[0]);
2474 return 0;
2475}
2476
2477void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
2478 struct btrfs_backref_cache *cache, int is_reloc)
2479{
2480 int i;
2481
2482 cache->rb_root = RB_ROOT;
2483 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
2484 INIT_LIST_HEAD(&cache->pending[i]);
2485 INIT_LIST_HEAD(&cache->changed);
2486 INIT_LIST_HEAD(&cache->detached);
2487 INIT_LIST_HEAD(&cache->leaves);
2488 INIT_LIST_HEAD(&cache->pending_edge);
2489 INIT_LIST_HEAD(&cache->useless_node);
2490 cache->fs_info = fs_info;
2491 cache->is_reloc = is_reloc;
2492}
2493
2494struct btrfs_backref_node *btrfs_backref_alloc_node(
2495 struct btrfs_backref_cache *cache, u64 bytenr, int level)
2496{
2497 struct btrfs_backref_node *node;
2498
2499 ASSERT(level >= 0 && level < BTRFS_MAX_LEVEL);
2500 node = kzalloc(sizeof(*node), GFP_NOFS);
2501 if (!node)
2502 return node;
2503
2504 INIT_LIST_HEAD(&node->list);
2505 INIT_LIST_HEAD(&node->upper);
2506 INIT_LIST_HEAD(&node->lower);
2507 RB_CLEAR_NODE(&node->rb_node);
2508 cache->nr_nodes++;
2509 node->level = level;
2510 node->bytenr = bytenr;
2511
2512 return node;
2513}
2514
2515struct btrfs_backref_edge *btrfs_backref_alloc_edge(
2516 struct btrfs_backref_cache *cache)
2517{
2518 struct btrfs_backref_edge *edge;
2519
2520 edge = kzalloc(sizeof(*edge), GFP_NOFS);
2521 if (edge)
2522 cache->nr_edges++;
2523 return edge;
2524}
2525
2526/*
2527 * Drop the backref node from cache, also cleaning up all its
2528 * upper edges and any uncached nodes in the path.
2529 *
2530 * This cleanup happens bottom up, thus the node should either
2531 * be the lowest node in the cache or a detached node.
2532 */
2533void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
2534 struct btrfs_backref_node *node)
2535{
2536 struct btrfs_backref_node *upper;
2537 struct btrfs_backref_edge *edge;
2538
2539 if (!node)
2540 return;
2541
2542 BUG_ON(!node->lowest && !node->detached);
2543 while (!list_empty(&node->upper)) {
2544 edge = list_entry(node->upper.next, struct btrfs_backref_edge,
2545 list[LOWER]);
2546 upper = edge->node[UPPER];
2547 list_del(&edge->list[LOWER]);
2548 list_del(&edge->list[UPPER]);
2549 btrfs_backref_free_edge(cache, edge);
2550
2551 /*
2552 * Add the node to leaf node list if no other child block
2553 * cached.
2554 */
2555 if (list_empty(&upper->lower)) {
2556 list_add_tail(&upper->lower, &cache->leaves);
2557 upper->lowest = 1;
2558 }
2559 }
2560
2561 btrfs_backref_drop_node(cache, node);
2562}
2563
2564/*
2565 * Release all nodes/edges from current cache
2566 */
2567void btrfs_backref_release_cache(struct btrfs_backref_cache *cache)
2568{
2569 struct btrfs_backref_node *node;
2570 int i;
2571
2572 while (!list_empty(&cache->detached)) {
2573 node = list_entry(cache->detached.next,
2574 struct btrfs_backref_node, list);
2575 btrfs_backref_cleanup_node(cache, node);
2576 }
2577
2578 while (!list_empty(&cache->leaves)) {
2579 node = list_entry(cache->leaves.next,
2580 struct btrfs_backref_node, lower);
2581 btrfs_backref_cleanup_node(cache, node);
2582 }
2583
2584 cache->last_trans = 0;
2585
2586 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
2587 ASSERT(list_empty(&cache->pending[i]));
2588 ASSERT(list_empty(&cache->pending_edge));
2589 ASSERT(list_empty(&cache->useless_node));
2590 ASSERT(list_empty(&cache->changed));
2591 ASSERT(list_empty(&cache->detached));
2592 ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
2593 ASSERT(!cache->nr_nodes);
2594 ASSERT(!cache->nr_edges);
2595}
2596
2597/*
2598 * Handle direct tree backref
2599 *
2600 * Direct tree backref means, the backref item shows its parent bytenr
2601 * directly. This is for SHARED_BLOCK_REF backref (keyed or inlined).
2602 *
2603 * @ref_key: The converted backref key.
2604 * For keyed backref, it's the item key.
2605 * For inlined backref, objectid is the bytenr,
2606 * type is btrfs_inline_ref_type, offset is
2607 * btrfs_inline_ref_offset.
2608 */
2609static int handle_direct_tree_backref(struct btrfs_backref_cache *cache,
2610 struct btrfs_key *ref_key,
2611 struct btrfs_backref_node *cur)
2612{
2613 struct btrfs_backref_edge *edge;
2614 struct btrfs_backref_node *upper;
2615 struct rb_node *rb_node;
2616
2617 ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY);
2618
2619 /* Only reloc root uses backref pointing to itself */
2620 if (ref_key->objectid == ref_key->offset) {
2621 struct btrfs_root *root;
2622
2623 cur->is_reloc_root = 1;
2624 /* Only reloc backref cache cares about a specific root */
2625 if (cache->is_reloc) {
2626 root = find_reloc_root(cache->fs_info, cur->bytenr);
2627 if (!root)
2628 return -ENOENT;
2629 cur->root = root;
2630 } else {
2631 /*
2632 * For generic purpose backref cache, reloc root node
2633 * is useless.
2634 */
2635 list_add(&cur->list, &cache->useless_node);
2636 }
2637 return 0;
2638 }
2639
2640 edge = btrfs_backref_alloc_edge(cache);
2641 if (!edge)
2642 return -ENOMEM;
2643
2644 rb_node = rb_simple_search(&cache->rb_root, ref_key->offset);
2645 if (!rb_node) {
2646 /* Parent node not yet cached */
2647 upper = btrfs_backref_alloc_node(cache, ref_key->offset,
2648 cur->level + 1);
2649 if (!upper) {
2650 btrfs_backref_free_edge(cache, edge);
2651 return -ENOMEM;
2652 }
2653
2654 /*
2655 * Backrefs for the upper level block isn't cached, add the
2656 * block to pending list
2657 */
2658 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
2659 } else {
2660 /* Parent node already cached */
2661 upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
2662 ASSERT(upper->checked);
2663 INIT_LIST_HEAD(&edge->list[UPPER]);
2664 }
2665 btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER);
2666 return 0;
2667}
2668
2669/*
2670 * Handle indirect tree backref
2671 *
2672 * Indirect tree backref means, we only know which tree the node belongs to.
2673 * We still need to do a tree search to find out the parents. This is for
2674 * TREE_BLOCK_REF backref (keyed or inlined).
2675 *
2676 * @ref_key: The same as @ref_key in handle_direct_tree_backref()
2677 * @tree_key: The first key of this tree block.
2678 * @path: A clean (released) path, to avoid allocating path every time
2679 * the function get called.
2680 */
2681static int handle_indirect_tree_backref(struct btrfs_backref_cache *cache,
2682 struct btrfs_path *path,
2683 struct btrfs_key *ref_key,
2684 struct btrfs_key *tree_key,
2685 struct btrfs_backref_node *cur)
2686{
2687 struct btrfs_fs_info *fs_info = cache->fs_info;
2688 struct btrfs_backref_node *upper;
2689 struct btrfs_backref_node *lower;
2690 struct btrfs_backref_edge *edge;
2691 struct extent_buffer *eb;
2692 struct btrfs_root *root;
2693 struct rb_node *rb_node;
2694 int level;
2695 bool need_check = true;
2696 int ret;
2697
2698 root = btrfs_get_fs_root(fs_info, ref_key->offset, false);
2699 if (IS_ERR(root))
2700 return PTR_ERR(root);
2701 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
2702 cur->cowonly = 1;
2703
2704 if (btrfs_root_level(&root->root_item) == cur->level) {
2705 /* Tree root */
2706 ASSERT(btrfs_root_bytenr(&root->root_item) == cur->bytenr);
2707 /*
2708 * For reloc backref cache, we may ignore reloc root. But for
2709 * general purpose backref cache, we can't rely on
2710 * btrfs_should_ignore_reloc_root() as it may conflict with
2711 * current running relocation and lead to missing root.
2712 *
2713 * For general purpose backref cache, reloc root detection is
2714 * completely relying on direct backref (key->offset is parent
2715 * bytenr), thus only do such check for reloc cache.
2716 */
2717 if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) {
2718 btrfs_put_root(root);
2719 list_add(&cur->list, &cache->useless_node);
2720 } else {
2721 cur->root = root;
2722 }
2723 return 0;
2724 }
2725
2726 level = cur->level + 1;
2727
2728 /* Search the tree to find parent blocks referring to the block */
2729 path->search_commit_root = 1;
2730 path->skip_locking = 1;
2731 path->lowest_level = level;
2732 ret = btrfs_search_slot(NULL, root, tree_key, path, 0, 0);
2733 path->lowest_level = 0;
2734 if (ret < 0) {
2735 btrfs_put_root(root);
2736 return ret;
2737 }
2738 if (ret > 0 && path->slots[level] > 0)
2739 path->slots[level]--;
2740
2741 eb = path->nodes[level];
2742 if (btrfs_node_blockptr(eb, path->slots[level]) != cur->bytenr) {
2743 btrfs_err(fs_info,
2744"couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
2745 cur->bytenr, level - 1, root->root_key.objectid,
2746 tree_key->objectid, tree_key->type, tree_key->offset);
2747 btrfs_put_root(root);
2748 ret = -ENOENT;
2749 goto out;
2750 }
2751 lower = cur;
2752
2753 /* Add all nodes and edges in the path */
2754 for (; level < BTRFS_MAX_LEVEL; level++) {
2755 if (!path->nodes[level]) {
2756 ASSERT(btrfs_root_bytenr(&root->root_item) ==
2757 lower->bytenr);
2758 /* Same as previous should_ignore_reloc_root() call */
2759 if (btrfs_should_ignore_reloc_root(root) &&
2760 cache->is_reloc) {
2761 btrfs_put_root(root);
2762 list_add(&lower->list, &cache->useless_node);
2763 } else {
2764 lower->root = root;
2765 }
2766 break;
2767 }
2768
2769 edge = btrfs_backref_alloc_edge(cache);
2770 if (!edge) {
2771 btrfs_put_root(root);
2772 ret = -ENOMEM;
2773 goto out;
2774 }
2775
2776 eb = path->nodes[level];
2777 rb_node = rb_simple_search(&cache->rb_root, eb->start);
2778 if (!rb_node) {
2779 upper = btrfs_backref_alloc_node(cache, eb->start,
2780 lower->level + 1);
2781 if (!upper) {
2782 btrfs_put_root(root);
2783 btrfs_backref_free_edge(cache, edge);
2784 ret = -ENOMEM;
2785 goto out;
2786 }
2787 upper->owner = btrfs_header_owner(eb);
2788 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
2789 upper->cowonly = 1;
2790
2791 /*
2792 * If we know the block isn't shared we can avoid
2793 * checking its backrefs.
2794 */
2795 if (btrfs_block_can_be_shared(root, eb))
2796 upper->checked = 0;
2797 else
2798 upper->checked = 1;
2799
2800 /*
2801 * Add the block to pending list if we need to check its
2802 * backrefs, we only do this once while walking up a
2803 * tree as we will catch anything else later on.
2804 */
2805 if (!upper->checked && need_check) {
2806 need_check = false;
2807 list_add_tail(&edge->list[UPPER],
2808 &cache->pending_edge);
2809 } else {
2810 if (upper->checked)
2811 need_check = true;
2812 INIT_LIST_HEAD(&edge->list[UPPER]);
2813 }
2814 } else {
2815 upper = rb_entry(rb_node, struct btrfs_backref_node,
2816 rb_node);
2817 ASSERT(upper->checked);
2818 INIT_LIST_HEAD(&edge->list[UPPER]);
2819 if (!upper->owner)
2820 upper->owner = btrfs_header_owner(eb);
2821 }
2822 btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER);
2823
2824 if (rb_node) {
2825 btrfs_put_root(root);
2826 break;
2827 }
2828 lower = upper;
2829 upper = NULL;
2830 }
2831out:
2832 btrfs_release_path(path);
2833 return ret;
2834}
2835
2836/*
2837 * Add backref node @cur into @cache.
2838 *
2839 * NOTE: Even if the function returned 0, @cur is not yet cached as its upper
2840 * links aren't yet bi-directional. Needs to finish such links.
2841 * Use btrfs_backref_finish_upper_links() to finish such linkage.
2842 *
2843 * @path: Released path for indirect tree backref lookup
2844 * @iter: Released backref iter for extent tree search
2845 * @node_key: The first key of the tree block
2846 */
2847int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
2848 struct btrfs_path *path,
2849 struct btrfs_backref_iter *iter,
2850 struct btrfs_key *node_key,
2851 struct btrfs_backref_node *cur)
2852{
2853 struct btrfs_fs_info *fs_info = cache->fs_info;
2854 struct btrfs_backref_edge *edge;
2855 struct btrfs_backref_node *exist;
2856 int ret;
2857
2858 ret = btrfs_backref_iter_start(iter, cur->bytenr);
2859 if (ret < 0)
2860 return ret;
2861 /*
2862 * We skip the first btrfs_tree_block_info, as we don't use the key
2863 * stored in it, but fetch it from the tree block
2864 */
2865 if (btrfs_backref_has_tree_block_info(iter)) {
2866 ret = btrfs_backref_iter_next(iter);
2867 if (ret < 0)
2868 goto out;
2869 /* No extra backref? This means the tree block is corrupted */
2870 if (ret > 0) {
2871 ret = -EUCLEAN;
2872 goto out;
2873 }
2874 }
2875 WARN_ON(cur->checked);
2876 if (!list_empty(&cur->upper)) {
2877 /*
2878 * The backref was added previously when processing backref of
2879 * type BTRFS_TREE_BLOCK_REF_KEY
2880 */
2881 ASSERT(list_is_singular(&cur->upper));
2882 edge = list_entry(cur->upper.next, struct btrfs_backref_edge,
2883 list[LOWER]);
2884 ASSERT(list_empty(&edge->list[UPPER]));
2885 exist = edge->node[UPPER];
2886 /*
2887 * Add the upper level block to pending list if we need check
2888 * its backrefs
2889 */
2890 if (!exist->checked)
2891 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
2892 } else {
2893 exist = NULL;
2894 }
2895
2896 for (; ret == 0; ret = btrfs_backref_iter_next(iter)) {
2897 struct extent_buffer *eb;
2898 struct btrfs_key key;
2899 int type;
2900
2901 cond_resched();
2902 eb = btrfs_backref_get_eb(iter);
2903
2904 key.objectid = iter->bytenr;
2905 if (btrfs_backref_iter_is_inline_ref(iter)) {
2906 struct btrfs_extent_inline_ref *iref;
2907
2908 /* Update key for inline backref */
2909 iref = (struct btrfs_extent_inline_ref *)
2910 ((unsigned long)iter->cur_ptr);
2911 type = btrfs_get_extent_inline_ref_type(eb, iref,
2912 BTRFS_REF_TYPE_BLOCK);
2913 if (type == BTRFS_REF_TYPE_INVALID) {
2914 ret = -EUCLEAN;
2915 goto out;
2916 }
2917 key.type = type;
2918 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
2919 } else {
2920 key.type = iter->cur_key.type;
2921 key.offset = iter->cur_key.offset;
2922 }
2923
2924 /*
2925 * Parent node found and matches current inline ref, no need to
2926 * rebuild this node for this inline ref
2927 */
2928 if (exist &&
2929 ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
2930 exist->owner == key.offset) ||
2931 (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
2932 exist->bytenr == key.offset))) {
2933 exist = NULL;
2934 continue;
2935 }
2936
2937 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */
2938 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
2939 ret = handle_direct_tree_backref(cache, &key, cur);
2940 if (ret < 0)
2941 goto out;
2942 continue;
2943 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
2944 ret = -EINVAL;
2945 btrfs_print_v0_err(fs_info);
2946 btrfs_handle_fs_error(fs_info, ret, NULL);
2947 goto out;
2948 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
2949 continue;
2950 }
2951
2952 /*
2953 * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset
2954 * means the root objectid. We need to search the tree to get
2955 * its parent bytenr.
2956 */
2957 ret = handle_indirect_tree_backref(cache, path, &key, node_key,
2958 cur);
2959 if (ret < 0)
2960 goto out;
2961 }
2962 ret = 0;
2963 cur->checked = 1;
2964 WARN_ON(exist);
2965out:
2966 btrfs_backref_iter_release(iter);
2967 return ret;
2968}
2969
2970/*
2971 * Finish the upwards linkage created by btrfs_backref_add_tree_node()
2972 */
2973int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
2974 struct btrfs_backref_node *start)
2975{
2976 struct list_head *useless_node = &cache->useless_node;
2977 struct btrfs_backref_edge *edge;
2978 struct rb_node *rb_node;
2979 LIST_HEAD(pending_edge);
2980
2981 ASSERT(start->checked);
2982
2983 /* Insert this node to cache if it's not COW-only */
2984 if (!start->cowonly) {
2985 rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
2986 &start->rb_node);
2987 if (rb_node)
2988 btrfs_backref_panic(cache->fs_info, start->bytenr,
2989 -EEXIST);
2990 list_add_tail(&start->lower, &cache->leaves);
2991 }
2992
2993 /*
2994 * Use breadth first search to iterate all related edges.
2995 *
2996 * The starting points are all the edges of this node
2997 */
2998 list_for_each_entry(edge, &start->upper, list[LOWER])
2999 list_add_tail(&edge->list[UPPER], &pending_edge);
3000
3001 while (!list_empty(&pending_edge)) {
3002 struct btrfs_backref_node *upper;
3003 struct btrfs_backref_node *lower;
3004
3005 edge = list_first_entry(&pending_edge,
3006 struct btrfs_backref_edge, list[UPPER]);
3007 list_del_init(&edge->list[UPPER]);
3008 upper = edge->node[UPPER];
3009 lower = edge->node[LOWER];
3010
3011 /* Parent is detached, no need to keep any edges */
3012 if (upper->detached) {
3013 list_del(&edge->list[LOWER]);
3014 btrfs_backref_free_edge(cache, edge);
3015
3016 /* Lower node is orphan, queue for cleanup */
3017 if (list_empty(&lower->upper))
3018 list_add(&lower->list, useless_node);
3019 continue;
3020 }
3021
3022 /*
3023 * All new nodes added in current build_backref_tree() haven't
3024 * been linked to the cache rb tree.
3025 * So if we have upper->rb_node populated, this means a cache
3026 * hit. We only need to link the edge, as @upper and all its
3027 * parents have already been linked.
3028 */
3029 if (!RB_EMPTY_NODE(&upper->rb_node)) {
3030 if (upper->lowest) {
3031 list_del_init(&upper->lower);
3032 upper->lowest = 0;
3033 }
3034
3035 list_add_tail(&edge->list[UPPER], &upper->lower);
3036 continue;
3037 }
3038
3039 /* Sanity check, we shouldn't have any unchecked nodes */
3040 if (!upper->checked) {
3041 ASSERT(0);
3042 return -EUCLEAN;
3043 }
3044
3045 /* Sanity check, COW-only node has non-COW-only parent */
3046 if (start->cowonly != upper->cowonly) {
3047 ASSERT(0);
3048 return -EUCLEAN;
3049 }
3050
3051 /* Only cache non-COW-only (subvolume trees) tree blocks */
3052 if (!upper->cowonly) {
3053 rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
3054 &upper->rb_node);
3055 if (rb_node) {
3056 btrfs_backref_panic(cache->fs_info,
3057 upper->bytenr, -EEXIST);
3058 return -EUCLEAN;
3059 }
3060 }
3061
3062 list_add_tail(&edge->list[UPPER], &upper->lower);
3063
3064 /*
3065 * Also queue all the parent edges of this uncached node
3066 * to finish the upper linkage
3067 */
3068 list_for_each_entry(edge, &upper->upper, list[LOWER])
3069 list_add_tail(&edge->list[UPPER], &pending_edge);
3070 }
3071 return 0;
3072}
3073
3074void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
3075 struct btrfs_backref_node *node)
3076{
3077 struct btrfs_backref_node *lower;
3078 struct btrfs_backref_node *upper;
3079 struct btrfs_backref_edge *edge;
3080
3081 while (!list_empty(&cache->useless_node)) {
3082 lower = list_first_entry(&cache->useless_node,
3083 struct btrfs_backref_node, list);
3084 list_del_init(&lower->list);
3085 }
3086 while (!list_empty(&cache->pending_edge)) {
3087 edge = list_first_entry(&cache->pending_edge,
3088 struct btrfs_backref_edge, list[UPPER]);
3089 list_del(&edge->list[UPPER]);
3090 list_del(&edge->list[LOWER]);
3091 lower = edge->node[LOWER];
3092 upper = edge->node[UPPER];
3093 btrfs_backref_free_edge(cache, edge);
3094
3095 /*
3096 * Lower is no longer linked to any upper backref nodes and
3097 * isn't in the cache, we can free it ourselves.
3098 */
3099 if (list_empty(&lower->upper) &&
3100 RB_EMPTY_NODE(&lower->rb_node))
3101 list_add(&lower->list, &cache->useless_node);
3102
3103 if (!RB_EMPTY_NODE(&upper->rb_node))
3104 continue;
3105
3106 /* Add this guy's upper edges to the list to process */
3107 list_for_each_entry(edge, &upper->upper, list[LOWER])
3108 list_add_tail(&edge->list[UPPER],
3109 &cache->pending_edge);
3110 if (list_empty(&upper->upper))
3111 list_add(&upper->list, &cache->useless_node);
3112 }
3113
3114 while (!list_empty(&cache->useless_node)) {
3115 lower = list_first_entry(&cache->useless_node,
3116 struct btrfs_backref_node, list);
3117 list_del_init(&lower->list);
3118 if (lower == node)
3119 node = NULL;
3120 btrfs_backref_drop_node(cache, lower);
3121 }
3122
3123 btrfs_backref_cleanup_node(cache, node);
3124 ASSERT(list_empty(&cache->useless_node) &&
3125 list_empty(&cache->pending_edge));
3126}