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