1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2011 STRATO. All rights reserved.
7 #include <linux/rbtree.h>
8 #include <trace/events/btrfs.h>
13 #include "transaction.h"
14 #include "delayed-ref.h"
17 #include "tree-mod-log.h"
19 #include "accessors.h"
20 #include "extent-tree.h"
21 #include "relocation.h"
22 #include "tree-checker.h"
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
28 struct extent_inode_elem {
32 struct extent_inode_elem *next;
35 static 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)
41 const u64 data_len = btrfs_file_extent_num_bytes(eb, fi);
42 u64 offset = key->offset;
43 struct extent_inode_elem *e;
48 if (!ctx->ignore_extent_item_pos &&
49 !btrfs_file_extent_compression(eb, fi) &&
50 !btrfs_file_extent_encryption(eb, fi) &&
51 !btrfs_file_extent_other_encoding(eb, fi)) {
54 data_offset = btrfs_file_extent_offset(eb, fi);
56 if (ctx->extent_item_pos < data_offset ||
57 ctx->extent_item_pos >= data_offset + data_len)
59 offset += ctx->extent_item_pos - data_offset;
62 if (!ctx->indirect_ref_iterator || !ctx->cache_lookup)
65 cached = ctx->cache_lookup(eb->start, ctx->user_ctx, &root_ids,
70 for (int i = 0; i < root_count; i++) {
73 ret = ctx->indirect_ref_iterator(key->objectid, offset,
74 data_len, root_ids[i],
81 e = kmalloc(sizeof(*e), GFP_NOFS);
86 e->inum = key->objectid;
88 e->num_bytes = data_len;
94 static void free_inode_elem_list(struct extent_inode_elem *eie)
96 struct extent_inode_elem *eie_next;
98 for (; eie; eie = eie_next) {
104 static int find_extent_in_eb(struct btrfs_backref_walk_ctx *ctx,
105 const struct extent_buffer *eb,
106 struct extent_inode_elem **eie)
109 struct btrfs_key key;
110 struct btrfs_file_extent_item *fi;
117 * from the shared data ref, we only have the leaf but we need
118 * the key. thus, we must look into all items and see that we
119 * find one (some) with a reference to our extent item.
121 nritems = btrfs_header_nritems(eb);
122 for (slot = 0; slot < nritems; ++slot) {
123 btrfs_item_key_to_cpu(eb, &key, slot);
124 if (key.type != BTRFS_EXTENT_DATA_KEY)
126 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
127 extent_type = btrfs_file_extent_type(eb, fi);
128 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
130 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
131 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
132 if (disk_byte != ctx->bytenr)
135 ret = check_extent_in_eb(ctx, &key, eb, fi, eie);
136 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
144 struct rb_root_cached root;
148 #define PREFTREE_INIT { .root = RB_ROOT_CACHED, .count = 0 }
151 struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */
152 struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */
153 struct preftree indirect_missing_keys;
157 * Checks for a shared extent during backref search.
159 * The share_count tracks prelim_refs (direct and indirect) having a
161 * - incremented when a ref->count transitions to >0
162 * - decremented when a ref->count transitions to <1
165 struct btrfs_backref_share_check_ctx *ctx;
166 struct btrfs_root *root;
171 * Counts number of inodes that refer to an extent (different inodes in
172 * the same root or different roots) that we could find. The sharedness
173 * check typically stops once this counter gets greater than 1, so it
174 * may not reflect the total number of inodes.
178 * The number of times we found our inode refers to the data extent we
179 * are determining the sharedness. In other words, how many file extent
180 * items we could find for our inode that point to our target data
181 * extent. The value we get here after finishing the extent sharedness
182 * check may be smaller than reality, but if it ends up being greater
183 * than 1, then we know for sure the inode has multiple file extent
184 * items that point to our inode, and we can safely assume it's useful
185 * to cache the sharedness check result.
188 bool have_delayed_delete_refs;
191 static inline int extent_is_shared(struct share_check *sc)
193 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
196 static struct kmem_cache *btrfs_prelim_ref_cache;
198 int __init btrfs_prelim_ref_init(void)
200 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
201 sizeof(struct prelim_ref), 0, 0, NULL);
202 if (!btrfs_prelim_ref_cache)
207 void __cold btrfs_prelim_ref_exit(void)
209 kmem_cache_destroy(btrfs_prelim_ref_cache);
212 static void free_pref(struct prelim_ref *ref)
214 kmem_cache_free(btrfs_prelim_ref_cache, ref);
218 * Return 0 when both refs are for the same block (and can be merged).
219 * A -1 return indicates ref1 is a 'lower' block than ref2, while 1
220 * indicates a 'higher' block.
222 static int prelim_ref_compare(struct prelim_ref *ref1,
223 struct prelim_ref *ref2)
225 if (ref1->level < ref2->level)
227 if (ref1->level > ref2->level)
229 if (ref1->root_id < ref2->root_id)
231 if (ref1->root_id > ref2->root_id)
233 if (ref1->key_for_search.type < ref2->key_for_search.type)
235 if (ref1->key_for_search.type > ref2->key_for_search.type)
237 if (ref1->key_for_search.objectid < ref2->key_for_search.objectid)
239 if (ref1->key_for_search.objectid > ref2->key_for_search.objectid)
241 if (ref1->key_for_search.offset < ref2->key_for_search.offset)
243 if (ref1->key_for_search.offset > ref2->key_for_search.offset)
245 if (ref1->parent < ref2->parent)
247 if (ref1->parent > ref2->parent)
253 static void update_share_count(struct share_check *sc, int oldcount,
254 int newcount, struct prelim_ref *newref)
256 if ((!sc) || (oldcount == 0 && newcount < 1))
259 if (oldcount > 0 && newcount < 1)
261 else if (oldcount < 1 && newcount > 0)
264 if (newref->root_id == sc->root->root_key.objectid &&
265 newref->wanted_disk_byte == sc->data_bytenr &&
266 newref->key_for_search.objectid == sc->inum)
267 sc->self_ref_count += newref->count;
271 * Add @newref to the @root rbtree, merging identical refs.
273 * Callers should assume that newref has been freed after calling.
275 static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
276 struct preftree *preftree,
277 struct prelim_ref *newref,
278 struct share_check *sc)
280 struct rb_root_cached *root;
282 struct rb_node *parent = NULL;
283 struct prelim_ref *ref;
285 bool leftmost = true;
287 root = &preftree->root;
288 p = &root->rb_root.rb_node;
292 ref = rb_entry(parent, struct prelim_ref, rbnode);
293 result = prelim_ref_compare(ref, newref);
296 } else if (result > 0) {
300 /* Identical refs, merge them and free @newref */
301 struct extent_inode_elem *eie = ref->inode_list;
303 while (eie && eie->next)
307 ref->inode_list = newref->inode_list;
309 eie->next = newref->inode_list;
310 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
313 * A delayed ref can have newref->count < 0.
314 * The ref->count is updated to follow any
315 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
317 update_share_count(sc, ref->count,
318 ref->count + newref->count, newref);
319 ref->count += newref->count;
325 update_share_count(sc, 0, newref->count, newref);
327 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
328 rb_link_node(&newref->rbnode, parent, p);
329 rb_insert_color_cached(&newref->rbnode, root, leftmost);
333 * Release the entire tree. We don't care about internal consistency so
334 * just free everything and then reset the tree root.
336 static void prelim_release(struct preftree *preftree)
338 struct prelim_ref *ref, *next_ref;
340 rbtree_postorder_for_each_entry_safe(ref, next_ref,
341 &preftree->root.rb_root, rbnode) {
342 free_inode_elem_list(ref->inode_list);
346 preftree->root = RB_ROOT_CACHED;
351 * the rules for all callers of this function are:
352 * - obtaining the parent is the goal
353 * - if you add a key, you must know that it is a correct key
354 * - if you cannot add the parent or a correct key, then we will look into the
355 * block later to set a correct key
359 * backref type | shared | indirect | shared | indirect
360 * information | tree | tree | data | data
361 * --------------------+--------+----------+--------+----------
362 * parent logical | y | - | - | -
363 * key to resolve | - | y | y | y
364 * tree block logical | - | - | - | -
365 * root for resolving | y | y | y | y
367 * - column 1: we've the parent -> done
368 * - column 2, 3, 4: we use the key to find the parent
370 * on disk refs (inline or keyed)
371 * ==============================
372 * backref type | shared | indirect | shared | indirect
373 * information | tree | tree | data | data
374 * --------------------+--------+----------+--------+----------
375 * parent logical | y | - | y | -
376 * key to resolve | - | - | - | y
377 * tree block logical | y | y | y | y
378 * root for resolving | - | y | y | y
380 * - column 1, 3: we've the parent -> done
381 * - column 2: we take the first key from the block to find the parent
382 * (see add_missing_keys)
383 * - column 4: we use the key to find the parent
385 * additional information that's available but not required to find the parent
386 * block might help in merging entries to gain some speed.
388 static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
389 struct preftree *preftree, u64 root_id,
390 const struct btrfs_key *key, int level, u64 parent,
391 u64 wanted_disk_byte, int count,
392 struct share_check *sc, gfp_t gfp_mask)
394 struct prelim_ref *ref;
396 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
399 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
403 ref->root_id = root_id;
405 ref->key_for_search = *key;
407 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
409 ref->inode_list = NULL;
412 ref->parent = parent;
413 ref->wanted_disk_byte = wanted_disk_byte;
414 prelim_ref_insert(fs_info, preftree, ref, sc);
415 return extent_is_shared(sc);
418 /* direct refs use root == 0, key == NULL */
419 static int add_direct_ref(const struct btrfs_fs_info *fs_info,
420 struct preftrees *preftrees, int level, u64 parent,
421 u64 wanted_disk_byte, int count,
422 struct share_check *sc, gfp_t gfp_mask)
424 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
425 parent, wanted_disk_byte, count, sc, gfp_mask);
428 /* indirect refs use parent == 0 */
429 static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
430 struct preftrees *preftrees, u64 root_id,
431 const struct btrfs_key *key, int level,
432 u64 wanted_disk_byte, int count,
433 struct share_check *sc, gfp_t gfp_mask)
435 struct preftree *tree = &preftrees->indirect;
438 tree = &preftrees->indirect_missing_keys;
439 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
440 wanted_disk_byte, count, sc, gfp_mask);
443 static int is_shared_data_backref(struct preftrees *preftrees, u64 bytenr)
445 struct rb_node **p = &preftrees->direct.root.rb_root.rb_node;
446 struct rb_node *parent = NULL;
447 struct prelim_ref *ref = NULL;
448 struct prelim_ref target = {};
451 target.parent = bytenr;
455 ref = rb_entry(parent, struct prelim_ref, rbnode);
456 result = prelim_ref_compare(ref, &target);
468 static int add_all_parents(struct btrfs_backref_walk_ctx *ctx,
469 struct btrfs_root *root, struct btrfs_path *path,
470 struct ulist *parents,
471 struct preftrees *preftrees, struct prelim_ref *ref,
476 struct extent_buffer *eb;
477 struct btrfs_key key;
478 struct btrfs_key *key_for_search = &ref->key_for_search;
479 struct btrfs_file_extent_item *fi;
480 struct extent_inode_elem *eie = NULL, *old = NULL;
482 u64 wanted_disk_byte = ref->wanted_disk_byte;
488 eb = path->nodes[level];
489 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
496 * 1. We normally enter this function with the path already pointing to
497 * the first item to check. But sometimes, we may enter it with
499 * 2. We are searching for normal backref but bytenr of this leaf
500 * matches shared data backref
501 * 3. The leaf owner is not equal to the root we are searching
503 * For these cases, go to the next leaf before we continue.
506 if (path->slots[0] >= btrfs_header_nritems(eb) ||
507 is_shared_data_backref(preftrees, eb->start) ||
508 ref->root_id != btrfs_header_owner(eb)) {
509 if (ctx->time_seq == BTRFS_SEQ_LAST)
510 ret = btrfs_next_leaf(root, path);
512 ret = btrfs_next_old_leaf(root, path, ctx->time_seq);
515 while (!ret && count < ref->count) {
517 slot = path->slots[0];
519 btrfs_item_key_to_cpu(eb, &key, slot);
521 if (key.objectid != key_for_search->objectid ||
522 key.type != BTRFS_EXTENT_DATA_KEY)
526 * We are searching for normal backref but bytenr of this leaf
527 * matches shared data backref, OR
528 * the leaf owner is not equal to the root we are searching for
531 (is_shared_data_backref(preftrees, eb->start) ||
532 ref->root_id != btrfs_header_owner(eb))) {
533 if (ctx->time_seq == BTRFS_SEQ_LAST)
534 ret = btrfs_next_leaf(root, path);
536 ret = btrfs_next_old_leaf(root, path, ctx->time_seq);
539 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
540 type = btrfs_file_extent_type(eb, fi);
541 if (type == BTRFS_FILE_EXTENT_INLINE)
543 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
544 data_offset = btrfs_file_extent_offset(eb, fi);
546 if (disk_byte == wanted_disk_byte) {
549 if (ref->key_for_search.offset == key.offset - data_offset)
553 if (!ctx->skip_inode_ref_list) {
554 ret = check_extent_in_eb(ctx, &key, eb, fi, &eie);
555 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
561 ret = ulist_add_merge_ptr(parents, eb->start,
562 eie, (void **)&old, GFP_NOFS);
565 if (!ret && !ctx->skip_inode_ref_list) {
573 if (ctx->time_seq == BTRFS_SEQ_LAST)
574 ret = btrfs_next_item(root, path);
576 ret = btrfs_next_old_item(root, path, ctx->time_seq);
579 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
580 free_inode_elem_list(eie);
588 * resolve an indirect backref in the form (root_id, key, level)
589 * to a logical address
591 static int resolve_indirect_ref(struct btrfs_backref_walk_ctx *ctx,
592 struct btrfs_path *path,
593 struct preftrees *preftrees,
594 struct prelim_ref *ref, struct ulist *parents)
596 struct btrfs_root *root;
597 struct extent_buffer *eb;
600 int level = ref->level;
601 struct btrfs_key search_key = ref->key_for_search;
604 * If we're search_commit_root we could possibly be holding locks on
605 * other tree nodes. This happens when qgroups does backref walks when
606 * adding new delayed refs. To deal with this we need to look in cache
607 * for the root, and if we don't find it then we need to search the
608 * tree_root's commit root, thus the btrfs_get_fs_root_commit_root usage
611 if (path->search_commit_root)
612 root = btrfs_get_fs_root_commit_root(ctx->fs_info, path, ref->root_id);
614 root = btrfs_get_fs_root(ctx->fs_info, ref->root_id, false);
620 if (!path->search_commit_root &&
621 test_bit(BTRFS_ROOT_DELETING, &root->state)) {
626 if (btrfs_is_testing(ctx->fs_info)) {
631 if (path->search_commit_root)
632 root_level = btrfs_header_level(root->commit_root);
633 else if (ctx->time_seq == BTRFS_SEQ_LAST)
634 root_level = btrfs_header_level(root->node);
636 root_level = btrfs_old_root_level(root, ctx->time_seq);
638 if (root_level + 1 == level)
642 * We can often find data backrefs with an offset that is too large
643 * (>= LLONG_MAX, maximum allowed file offset) due to underflows when
644 * subtracting a file's offset with the data offset of its
645 * corresponding extent data item. This can happen for example in the
648 * So if we detect such case we set the search key's offset to zero to
649 * make sure we will find the matching file extent item at
650 * add_all_parents(), otherwise we will miss it because the offset
651 * taken form the backref is much larger then the offset of the file
652 * extent item. This can make us scan a very large number of file
653 * extent items, but at least it will not make us miss any.
655 * This is an ugly workaround for a behaviour that should have never
656 * existed, but it does and a fix for the clone ioctl would touch a lot
657 * of places, cause backwards incompatibility and would not fix the
658 * problem for extents cloned with older kernels.
660 if (search_key.type == BTRFS_EXTENT_DATA_KEY &&
661 search_key.offset >= LLONG_MAX)
662 search_key.offset = 0;
663 path->lowest_level = level;
664 if (ctx->time_seq == BTRFS_SEQ_LAST)
665 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
667 ret = btrfs_search_old_slot(root, &search_key, path, ctx->time_seq);
669 btrfs_debug(ctx->fs_info,
670 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
671 ref->root_id, level, ref->count, ret,
672 ref->key_for_search.objectid, ref->key_for_search.type,
673 ref->key_for_search.offset);
677 eb = path->nodes[level];
679 if (WARN_ON(!level)) {
684 eb = path->nodes[level];
687 ret = add_all_parents(ctx, root, path, parents, preftrees, ref, level);
689 btrfs_put_root(root);
691 path->lowest_level = 0;
692 btrfs_release_path(path);
696 static struct extent_inode_elem *
697 unode_aux_to_inode_list(struct ulist_node *node)
701 return (struct extent_inode_elem *)(uintptr_t)node->aux;
704 static void free_leaf_list(struct ulist *ulist)
706 struct ulist_node *node;
707 struct ulist_iterator uiter;
709 ULIST_ITER_INIT(&uiter);
710 while ((node = ulist_next(ulist, &uiter)))
711 free_inode_elem_list(unode_aux_to_inode_list(node));
717 * We maintain three separate rbtrees: one for direct refs, one for
718 * indirect refs which have a key, and one for indirect refs which do not
719 * have a key. Each tree does merge on insertion.
721 * Once all of the references are located, we iterate over the tree of
722 * indirect refs with missing keys. An appropriate key is located and
723 * the ref is moved onto the tree for indirect refs. After all missing
724 * keys are thus located, we iterate over the indirect ref tree, resolve
725 * each reference, and then insert the resolved reference onto the
726 * direct tree (merging there too).
728 * New backrefs (i.e., for parent nodes) are added to the appropriate
729 * rbtree as they are encountered. The new backrefs are subsequently
732 static int resolve_indirect_refs(struct btrfs_backref_walk_ctx *ctx,
733 struct btrfs_path *path,
734 struct preftrees *preftrees,
735 struct share_check *sc)
739 struct ulist *parents;
740 struct ulist_node *node;
741 struct ulist_iterator uiter;
742 struct rb_node *rnode;
744 parents = ulist_alloc(GFP_NOFS);
749 * We could trade memory usage for performance here by iterating
750 * the tree, allocating new refs for each insertion, and then
751 * freeing the entire indirect tree when we're done. In some test
752 * cases, the tree can grow quite large (~200k objects).
754 while ((rnode = rb_first_cached(&preftrees->indirect.root))) {
755 struct prelim_ref *ref;
757 ref = rb_entry(rnode, struct prelim_ref, rbnode);
758 if (WARN(ref->parent,
759 "BUG: direct ref found in indirect tree")) {
764 rb_erase_cached(&ref->rbnode, &preftrees->indirect.root);
765 preftrees->indirect.count--;
767 if (ref->count == 0) {
772 if (sc && ref->root_id != sc->root->root_key.objectid) {
774 ret = BACKREF_FOUND_SHARED;
777 err = resolve_indirect_ref(ctx, path, preftrees, ref, parents);
779 * we can only tolerate ENOENT,otherwise,we should catch error
780 * and return directly.
782 if (err == -ENOENT) {
783 prelim_ref_insert(ctx->fs_info, &preftrees->direct, ref,
792 /* we put the first parent into the ref at hand */
793 ULIST_ITER_INIT(&uiter);
794 node = ulist_next(parents, &uiter);
795 ref->parent = node ? node->val : 0;
796 ref->inode_list = unode_aux_to_inode_list(node);
798 /* Add a prelim_ref(s) for any other parent(s). */
799 while ((node = ulist_next(parents, &uiter))) {
800 struct prelim_ref *new_ref;
802 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
809 memcpy(new_ref, ref, sizeof(*ref));
810 new_ref->parent = node->val;
811 new_ref->inode_list = unode_aux_to_inode_list(node);
812 prelim_ref_insert(ctx->fs_info, &preftrees->direct,
817 * Now it's a direct ref, put it in the direct tree. We must
818 * do this last because the ref could be merged/freed here.
820 prelim_ref_insert(ctx->fs_info, &preftrees->direct, ref, NULL);
822 ulist_reinit(parents);
827 * We may have inode lists attached to refs in the parents ulist, so we
828 * must free them before freeing the ulist and its refs.
830 free_leaf_list(parents);
835 * read tree blocks and add keys where required.
837 static int add_missing_keys(struct btrfs_fs_info *fs_info,
838 struct preftrees *preftrees, bool lock)
840 struct prelim_ref *ref;
841 struct extent_buffer *eb;
842 struct preftree *tree = &preftrees->indirect_missing_keys;
843 struct rb_node *node;
845 while ((node = rb_first_cached(&tree->root))) {
846 struct btrfs_tree_parent_check check = { 0 };
848 ref = rb_entry(node, struct prelim_ref, rbnode);
849 rb_erase_cached(node, &tree->root);
851 BUG_ON(ref->parent); /* should not be a direct ref */
852 BUG_ON(ref->key_for_search.type);
853 BUG_ON(!ref->wanted_disk_byte);
855 check.level = ref->level - 1;
856 check.owner_root = ref->root_id;
858 eb = read_tree_block(fs_info, ref->wanted_disk_byte, &check);
863 if (!extent_buffer_uptodate(eb)) {
865 free_extent_buffer(eb);
870 btrfs_tree_read_lock(eb);
871 if (btrfs_header_level(eb) == 0)
872 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
874 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
876 btrfs_tree_read_unlock(eb);
877 free_extent_buffer(eb);
878 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
885 * add all currently queued delayed refs from this head whose seq nr is
886 * smaller or equal that seq to the list
888 static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
889 struct btrfs_delayed_ref_head *head, u64 seq,
890 struct preftrees *preftrees, struct share_check *sc)
892 struct btrfs_delayed_ref_node *node;
893 struct btrfs_key key;
898 spin_lock(&head->lock);
899 for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
900 node = rb_entry(n, struct btrfs_delayed_ref_node,
905 switch (node->action) {
906 case BTRFS_ADD_DELAYED_EXTENT:
907 case BTRFS_UPDATE_DELAYED_HEAD:
910 case BTRFS_ADD_DELAYED_REF:
911 count = node->ref_mod;
913 case BTRFS_DROP_DELAYED_REF:
914 count = node->ref_mod * -1;
919 switch (node->type) {
920 case BTRFS_TREE_BLOCK_REF_KEY: {
921 /* NORMAL INDIRECT METADATA backref */
922 struct btrfs_delayed_tree_ref *ref;
923 struct btrfs_key *key_ptr = NULL;
925 if (head->extent_op && head->extent_op->update_key) {
926 btrfs_disk_key_to_cpu(&key, &head->extent_op->key);
930 ref = btrfs_delayed_node_to_tree_ref(node);
931 ret = add_indirect_ref(fs_info, preftrees, ref->root,
932 key_ptr, ref->level + 1,
933 node->bytenr, count, sc,
937 case BTRFS_SHARED_BLOCK_REF_KEY: {
938 /* SHARED DIRECT METADATA backref */
939 struct btrfs_delayed_tree_ref *ref;
941 ref = btrfs_delayed_node_to_tree_ref(node);
943 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
944 ref->parent, node->bytenr, count,
948 case BTRFS_EXTENT_DATA_REF_KEY: {
949 /* NORMAL INDIRECT DATA backref */
950 struct btrfs_delayed_data_ref *ref;
951 ref = btrfs_delayed_node_to_data_ref(node);
953 key.objectid = ref->objectid;
954 key.type = BTRFS_EXTENT_DATA_KEY;
955 key.offset = ref->offset;
958 * If we have a share check context and a reference for
959 * another inode, we can't exit immediately. This is
960 * because even if this is a BTRFS_ADD_DELAYED_REF
961 * reference we may find next a BTRFS_DROP_DELAYED_REF
962 * which cancels out this ADD reference.
964 * If this is a DROP reference and there was no previous
965 * ADD reference, then we need to signal that when we
966 * process references from the extent tree (through
967 * add_inline_refs() and add_keyed_refs()), we should
968 * not exit early if we find a reference for another
969 * inode, because one of the delayed DROP references
970 * may cancel that reference in the extent tree.
973 sc->have_delayed_delete_refs = true;
975 ret = add_indirect_ref(fs_info, preftrees, ref->root,
976 &key, 0, node->bytenr, count, sc,
980 case BTRFS_SHARED_DATA_REF_KEY: {
981 /* SHARED DIRECT FULL backref */
982 struct btrfs_delayed_data_ref *ref;
984 ref = btrfs_delayed_node_to_data_ref(node);
986 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
987 node->bytenr, count, sc,
995 * We must ignore BACKREF_FOUND_SHARED until all delayed
996 * refs have been checked.
998 if (ret && (ret != BACKREF_FOUND_SHARED))
1002 ret = extent_is_shared(sc);
1004 spin_unlock(&head->lock);
1009 * add all inline backrefs for bytenr to the list
1011 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
1013 static int add_inline_refs(struct btrfs_backref_walk_ctx *ctx,
1014 struct btrfs_path *path,
1015 int *info_level, struct preftrees *preftrees,
1016 struct share_check *sc)
1020 struct extent_buffer *leaf;
1021 struct btrfs_key key;
1022 struct btrfs_key found_key;
1025 struct btrfs_extent_item *ei;
1030 * enumerate all inline refs
1032 leaf = path->nodes[0];
1033 slot = path->slots[0];
1035 item_size = btrfs_item_size(leaf, slot);
1036 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
1038 if (ctx->check_extent_item) {
1039 ret = ctx->check_extent_item(ctx->bytenr, ei, leaf, ctx->user_ctx);
1044 flags = btrfs_extent_flags(leaf, ei);
1045 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1047 ptr = (unsigned long)(ei + 1);
1048 end = (unsigned long)ei + item_size;
1050 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
1051 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1052 struct btrfs_tree_block_info *info;
1054 info = (struct btrfs_tree_block_info *)ptr;
1055 *info_level = btrfs_tree_block_level(leaf, info);
1056 ptr += sizeof(struct btrfs_tree_block_info);
1058 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
1059 *info_level = found_key.offset;
1061 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
1065 struct btrfs_extent_inline_ref *iref;
1069 iref = (struct btrfs_extent_inline_ref *)ptr;
1070 type = btrfs_get_extent_inline_ref_type(leaf, iref,
1071 BTRFS_REF_TYPE_ANY);
1072 if (type == BTRFS_REF_TYPE_INVALID)
1075 offset = btrfs_extent_inline_ref_offset(leaf, iref);
1078 case BTRFS_SHARED_BLOCK_REF_KEY:
1079 ret = add_direct_ref(ctx->fs_info, preftrees,
1080 *info_level + 1, offset,
1081 ctx->bytenr, 1, NULL, GFP_NOFS);
1083 case BTRFS_SHARED_DATA_REF_KEY: {
1084 struct btrfs_shared_data_ref *sdref;
1087 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
1088 count = btrfs_shared_data_ref_count(leaf, sdref);
1090 ret = add_direct_ref(ctx->fs_info, preftrees, 0, offset,
1091 ctx->bytenr, count, sc, GFP_NOFS);
1094 case BTRFS_TREE_BLOCK_REF_KEY:
1095 ret = add_indirect_ref(ctx->fs_info, preftrees, offset,
1096 NULL, *info_level + 1,
1097 ctx->bytenr, 1, NULL, GFP_NOFS);
1099 case BTRFS_EXTENT_DATA_REF_KEY: {
1100 struct btrfs_extent_data_ref *dref;
1104 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1105 count = btrfs_extent_data_ref_count(leaf, dref);
1106 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1108 key.type = BTRFS_EXTENT_DATA_KEY;
1109 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1111 if (sc && key.objectid != sc->inum &&
1112 !sc->have_delayed_delete_refs) {
1113 ret = BACKREF_FOUND_SHARED;
1117 root = btrfs_extent_data_ref_root(leaf, dref);
1119 if (!ctx->skip_data_ref ||
1120 !ctx->skip_data_ref(root, key.objectid, key.offset,
1122 ret = add_indirect_ref(ctx->fs_info, preftrees,
1123 root, &key, 0, ctx->bytenr,
1124 count, sc, GFP_NOFS);
1127 case BTRFS_EXTENT_OWNER_REF_KEY:
1128 ASSERT(btrfs_fs_incompat(ctx->fs_info, SIMPLE_QUOTA));
1135 ptr += btrfs_extent_inline_ref_size(type);
1142 * add all non-inline backrefs for bytenr to the list
1144 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
1146 static int add_keyed_refs(struct btrfs_backref_walk_ctx *ctx,
1147 struct btrfs_root *extent_root,
1148 struct btrfs_path *path,
1149 int info_level, struct preftrees *preftrees,
1150 struct share_check *sc)
1152 struct btrfs_fs_info *fs_info = extent_root->fs_info;
1155 struct extent_buffer *leaf;
1156 struct btrfs_key key;
1159 ret = btrfs_next_item(extent_root, path);
1167 slot = path->slots[0];
1168 leaf = path->nodes[0];
1169 btrfs_item_key_to_cpu(leaf, &key, slot);
1171 if (key.objectid != ctx->bytenr)
1173 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1175 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1179 case BTRFS_SHARED_BLOCK_REF_KEY:
1180 /* SHARED DIRECT METADATA backref */
1181 ret = add_direct_ref(fs_info, preftrees,
1182 info_level + 1, key.offset,
1183 ctx->bytenr, 1, NULL, GFP_NOFS);
1185 case BTRFS_SHARED_DATA_REF_KEY: {
1186 /* SHARED DIRECT FULL backref */
1187 struct btrfs_shared_data_ref *sdref;
1190 sdref = btrfs_item_ptr(leaf, slot,
1191 struct btrfs_shared_data_ref);
1192 count = btrfs_shared_data_ref_count(leaf, sdref);
1193 ret = add_direct_ref(fs_info, preftrees, 0,
1194 key.offset, ctx->bytenr, count,
1198 case BTRFS_TREE_BLOCK_REF_KEY:
1199 /* NORMAL INDIRECT METADATA backref */
1200 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1201 NULL, info_level + 1, ctx->bytenr,
1204 case BTRFS_EXTENT_DATA_REF_KEY: {
1205 /* NORMAL INDIRECT DATA backref */
1206 struct btrfs_extent_data_ref *dref;
1210 dref = btrfs_item_ptr(leaf, slot,
1211 struct btrfs_extent_data_ref);
1212 count = btrfs_extent_data_ref_count(leaf, dref);
1213 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1215 key.type = BTRFS_EXTENT_DATA_KEY;
1216 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1218 if (sc && key.objectid != sc->inum &&
1219 !sc->have_delayed_delete_refs) {
1220 ret = BACKREF_FOUND_SHARED;
1224 root = btrfs_extent_data_ref_root(leaf, dref);
1226 if (!ctx->skip_data_ref ||
1227 !ctx->skip_data_ref(root, key.objectid, key.offset,
1229 ret = add_indirect_ref(fs_info, preftrees, root,
1230 &key, 0, ctx->bytenr,
1231 count, sc, GFP_NOFS);
1246 * The caller has joined a transaction or is holding a read lock on the
1247 * fs_info->commit_root_sem semaphore, so no need to worry about the root's last
1248 * snapshot field changing while updating or checking the cache.
1250 static bool lookup_backref_shared_cache(struct btrfs_backref_share_check_ctx *ctx,
1251 struct btrfs_root *root,
1252 u64 bytenr, int level, bool *is_shared)
1254 const struct btrfs_fs_info *fs_info = root->fs_info;
1255 struct btrfs_backref_shared_cache_entry *entry;
1257 if (!current->journal_info)
1258 lockdep_assert_held(&fs_info->commit_root_sem);
1260 if (!ctx->use_path_cache)
1263 if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL))
1267 * Level -1 is used for the data extent, which is not reliable to cache
1268 * because its reference count can increase or decrease without us
1269 * realizing. We cache results only for extent buffers that lead from
1270 * the root node down to the leaf with the file extent item.
1274 entry = &ctx->path_cache_entries[level];
1276 /* Unused cache entry or being used for some other extent buffer. */
1277 if (entry->bytenr != bytenr)
1281 * We cached a false result, but the last snapshot generation of the
1282 * root changed, so we now have a snapshot. Don't trust the result.
1284 if (!entry->is_shared &&
1285 entry->gen != btrfs_root_last_snapshot(&root->root_item))
1289 * If we cached a true result and the last generation used for dropping
1290 * a root changed, we can not trust the result, because the dropped root
1291 * could be a snapshot sharing this extent buffer.
1293 if (entry->is_shared &&
1294 entry->gen != btrfs_get_last_root_drop_gen(fs_info))
1297 *is_shared = entry->is_shared;
1299 * If the node at this level is shared, than all nodes below are also
1300 * shared. Currently some of the nodes below may be marked as not shared
1301 * because we have just switched from one leaf to another, and switched
1302 * also other nodes above the leaf and below the current level, so mark
1306 for (int i = 0; i < level; i++) {
1307 ctx->path_cache_entries[i].is_shared = true;
1308 ctx->path_cache_entries[i].gen = entry->gen;
1316 * The caller has joined a transaction or is holding a read lock on the
1317 * fs_info->commit_root_sem semaphore, so no need to worry about the root's last
1318 * snapshot field changing while updating or checking the cache.
1320 static void store_backref_shared_cache(struct btrfs_backref_share_check_ctx *ctx,
1321 struct btrfs_root *root,
1322 u64 bytenr, int level, bool is_shared)
1324 const struct btrfs_fs_info *fs_info = root->fs_info;
1325 struct btrfs_backref_shared_cache_entry *entry;
1328 if (!current->journal_info)
1329 lockdep_assert_held(&fs_info->commit_root_sem);
1331 if (!ctx->use_path_cache)
1334 if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL))
1338 * Level -1 is used for the data extent, which is not reliable to cache
1339 * because its reference count can increase or decrease without us
1340 * realizing. We cache results only for extent buffers that lead from
1341 * the root node down to the leaf with the file extent item.
1346 gen = btrfs_get_last_root_drop_gen(fs_info);
1348 gen = btrfs_root_last_snapshot(&root->root_item);
1350 entry = &ctx->path_cache_entries[level];
1351 entry->bytenr = bytenr;
1352 entry->is_shared = is_shared;
1356 * If we found an extent buffer is shared, set the cache result for all
1357 * extent buffers below it to true. As nodes in the path are COWed,
1358 * their sharedness is moved to their children, and if a leaf is COWed,
1359 * then the sharedness of a data extent becomes direct, the refcount of
1360 * data extent is increased in the extent item at the extent tree.
1363 for (int i = 0; i < level; i++) {
1364 entry = &ctx->path_cache_entries[i];
1365 entry->is_shared = is_shared;
1372 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1373 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1374 * indirect refs to their parent bytenr.
1375 * When roots are found, they're added to the roots list
1377 * @ctx: Backref walking context object, must be not NULL.
1378 * @sc: If !NULL, then immediately return BACKREF_FOUND_SHARED when a
1379 * shared extent is detected.
1381 * Otherwise this returns 0 for success and <0 for an error.
1383 * FIXME some caching might speed things up
1385 static int find_parent_nodes(struct btrfs_backref_walk_ctx *ctx,
1386 struct share_check *sc)
1388 struct btrfs_root *root = btrfs_extent_root(ctx->fs_info, ctx->bytenr);
1389 struct btrfs_key key;
1390 struct btrfs_path *path;
1391 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1392 struct btrfs_delayed_ref_head *head;
1395 struct prelim_ref *ref;
1396 struct rb_node *node;
1397 struct extent_inode_elem *eie = NULL;
1398 struct preftrees preftrees = {
1399 .direct = PREFTREE_INIT,
1400 .indirect = PREFTREE_INIT,
1401 .indirect_missing_keys = PREFTREE_INIT
1404 /* Roots ulist is not needed when using a sharedness check context. */
1406 ASSERT(ctx->roots == NULL);
1408 key.objectid = ctx->bytenr;
1409 key.offset = (u64)-1;
1410 if (btrfs_fs_incompat(ctx->fs_info, SKINNY_METADATA))
1411 key.type = BTRFS_METADATA_ITEM_KEY;
1413 key.type = BTRFS_EXTENT_ITEM_KEY;
1415 path = btrfs_alloc_path();
1419 path->search_commit_root = 1;
1420 path->skip_locking = 1;
1423 if (ctx->time_seq == BTRFS_SEQ_LAST)
1424 path->skip_locking = 1;
1429 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1434 * Key with offset -1 found, there would have to exist an extent
1435 * item with such offset, but this is out of the valid range.
1441 if (ctx->trans && likely(ctx->trans->type != __TRANS_DUMMY) &&
1442 ctx->time_seq != BTRFS_SEQ_LAST) {
1444 * We have a specific time_seq we care about and trans which
1445 * means we have the path lock, we need to grab the ref head and
1446 * lock it so we have a consistent view of the refs at the given
1449 delayed_refs = &ctx->trans->transaction->delayed_refs;
1450 spin_lock(&delayed_refs->lock);
1451 head = btrfs_find_delayed_ref_head(delayed_refs, ctx->bytenr);
1453 if (!mutex_trylock(&head->mutex)) {
1454 refcount_inc(&head->refs);
1455 spin_unlock(&delayed_refs->lock);
1457 btrfs_release_path(path);
1460 * Mutex was contended, block until it's
1461 * released and try again
1463 mutex_lock(&head->mutex);
1464 mutex_unlock(&head->mutex);
1465 btrfs_put_delayed_ref_head(head);
1468 spin_unlock(&delayed_refs->lock);
1469 ret = add_delayed_refs(ctx->fs_info, head, ctx->time_seq,
1471 mutex_unlock(&head->mutex);
1475 spin_unlock(&delayed_refs->lock);
1479 if (path->slots[0]) {
1480 struct extent_buffer *leaf;
1484 leaf = path->nodes[0];
1485 slot = path->slots[0];
1486 btrfs_item_key_to_cpu(leaf, &key, slot);
1487 if (key.objectid == ctx->bytenr &&
1488 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1489 key.type == BTRFS_METADATA_ITEM_KEY)) {
1490 ret = add_inline_refs(ctx, path, &info_level,
1494 ret = add_keyed_refs(ctx, root, path, info_level,
1502 * If we have a share context and we reached here, it means the extent
1503 * is not directly shared (no multiple reference items for it),
1504 * otherwise we would have exited earlier with a return value of
1505 * BACKREF_FOUND_SHARED after processing delayed references or while
1506 * processing inline or keyed references from the extent tree.
1507 * The extent may however be indirectly shared through shared subtrees
1508 * as a result from creating snapshots, so we determine below what is
1509 * its parent node, in case we are dealing with a metadata extent, or
1510 * what's the leaf (or leaves), from a fs tree, that has a file extent
1511 * item pointing to it in case we are dealing with a data extent.
1513 ASSERT(extent_is_shared(sc) == 0);
1516 * If we are here for a data extent and we have a share_check structure
1517 * it means the data extent is not directly shared (does not have
1518 * multiple reference items), so we have to check if a path in the fs
1519 * tree (going from the root node down to the leaf that has the file
1520 * extent item pointing to the data extent) is shared, that is, if any
1521 * of the extent buffers in the path is referenced by other trees.
1523 if (sc && ctx->bytenr == sc->data_bytenr) {
1525 * If our data extent is from a generation more recent than the
1526 * last generation used to snapshot the root, then we know that
1527 * it can not be shared through subtrees, so we can skip
1528 * resolving indirect references, there's no point in
1529 * determining the extent buffers for the path from the fs tree
1530 * root node down to the leaf that has the file extent item that
1531 * points to the data extent.
1533 if (sc->data_extent_gen >
1534 btrfs_root_last_snapshot(&sc->root->root_item)) {
1535 ret = BACKREF_FOUND_NOT_SHARED;
1540 * If we are only determining if a data extent is shared or not
1541 * and the corresponding file extent item is located in the same
1542 * leaf as the previous file extent item, we can skip resolving
1543 * indirect references for a data extent, since the fs tree path
1544 * is the same (same leaf, so same path). We skip as long as the
1545 * cached result for the leaf is valid and only if there's only
1546 * one file extent item pointing to the data extent, because in
1547 * the case of multiple file extent items, they may be located
1548 * in different leaves and therefore we have multiple paths.
1550 if (sc->ctx->curr_leaf_bytenr == sc->ctx->prev_leaf_bytenr &&
1551 sc->self_ref_count == 1) {
1555 cached = lookup_backref_shared_cache(sc->ctx, sc->root,
1556 sc->ctx->curr_leaf_bytenr,
1560 ret = BACKREF_FOUND_SHARED;
1562 ret = BACKREF_FOUND_NOT_SHARED;
1568 btrfs_release_path(path);
1570 ret = add_missing_keys(ctx->fs_info, &preftrees, path->skip_locking == 0);
1574 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root));
1576 ret = resolve_indirect_refs(ctx, path, &preftrees, sc);
1580 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root));
1583 * This walks the tree of merged and resolved refs. Tree blocks are
1584 * read in as needed. Unique entries are added to the ulist, and
1585 * the list of found roots is updated.
1587 * We release the entire tree in one go before returning.
1589 node = rb_first_cached(&preftrees.direct.root);
1591 ref = rb_entry(node, struct prelim_ref, rbnode);
1592 node = rb_next(&ref->rbnode);
1594 * ref->count < 0 can happen here if there are delayed
1595 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1596 * prelim_ref_insert() relies on this when merging
1597 * identical refs to keep the overall count correct.
1598 * prelim_ref_insert() will merge only those refs
1599 * which compare identically. Any refs having
1600 * e.g. different offsets would not be merged,
1601 * and would retain their original ref->count < 0.
1603 if (ctx->roots && ref->count && ref->root_id && ref->parent == 0) {
1604 /* no parent == root of tree */
1605 ret = ulist_add(ctx->roots, ref->root_id, 0, GFP_NOFS);
1609 if (ref->count && ref->parent) {
1610 if (!ctx->skip_inode_ref_list && !ref->inode_list &&
1612 struct btrfs_tree_parent_check check = { 0 };
1613 struct extent_buffer *eb;
1615 check.level = ref->level;
1617 eb = read_tree_block(ctx->fs_info, ref->parent,
1623 if (!extent_buffer_uptodate(eb)) {
1624 free_extent_buffer(eb);
1629 if (!path->skip_locking)
1630 btrfs_tree_read_lock(eb);
1631 ret = find_extent_in_eb(ctx, eb, &eie);
1632 if (!path->skip_locking)
1633 btrfs_tree_read_unlock(eb);
1634 free_extent_buffer(eb);
1635 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
1638 ref->inode_list = eie;
1640 * We transferred the list ownership to the ref,
1641 * so set to NULL to avoid a double free in case
1642 * an error happens after this.
1646 ret = ulist_add_merge_ptr(ctx->refs, ref->parent,
1648 (void **)&eie, GFP_NOFS);
1651 if (!ret && !ctx->skip_inode_ref_list) {
1653 * We've recorded that parent, so we must extend
1654 * its inode list here.
1656 * However if there was corruption we may not
1657 * have found an eie, return an error in this
1667 eie->next = ref->inode_list;
1671 * We have transferred the inode list ownership from
1672 * this ref to the ref we added to the 'refs' ulist.
1673 * So set this ref's inode list to NULL to avoid
1674 * use-after-free when our caller uses it or double
1675 * frees in case an error happens before we return.
1677 ref->inode_list = NULL;
1683 btrfs_free_path(path);
1685 prelim_release(&preftrees.direct);
1686 prelim_release(&preftrees.indirect);
1687 prelim_release(&preftrees.indirect_missing_keys);
1689 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
1690 free_inode_elem_list(eie);
1695 * Finds all leaves with a reference to the specified combination of
1696 * @ctx->bytenr and @ctx->extent_item_pos. The bytenr of the found leaves are
1697 * added to the ulist at @ctx->refs, and that ulist is allocated by this
1698 * function. The caller should free the ulist with free_leaf_list() if
1699 * @ctx->ignore_extent_item_pos is false, otherwise a fimple ulist_free() is
1702 * Returns 0 on success and < 0 on error. On error @ctx->refs is not allocated.
1704 int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx)
1708 ASSERT(ctx->refs == NULL);
1710 ctx->refs = ulist_alloc(GFP_NOFS);
1714 ret = find_parent_nodes(ctx, NULL);
1715 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
1716 (ret < 0 && ret != -ENOENT)) {
1717 free_leaf_list(ctx->refs);
1726 * Walk all backrefs for a given extent to find all roots that reference this
1727 * extent. Walking a backref means finding all extents that reference this
1728 * extent and in turn walk the backrefs of those, too. Naturally this is a
1729 * recursive process, but here it is implemented in an iterative fashion: We
1730 * find all referencing extents for the extent in question and put them on a
1731 * list. In turn, we find all referencing extents for those, further appending
1732 * to the list. The way we iterate the list allows adding more elements after
1733 * the current while iterating. The process stops when we reach the end of the
1736 * Found roots are added to @ctx->roots, which is allocated by this function if
1737 * it points to NULL, in which case the caller is responsible for freeing it
1738 * after it's not needed anymore.
1739 * This function requires @ctx->refs to be NULL, as it uses it for allocating a
1740 * ulist to do temporary work, and frees it before returning.
1742 * Returns 0 on success, < 0 on error.
1744 static int btrfs_find_all_roots_safe(struct btrfs_backref_walk_ctx *ctx)
1746 const u64 orig_bytenr = ctx->bytenr;
1747 const bool orig_skip_inode_ref_list = ctx->skip_inode_ref_list;
1748 bool roots_ulist_allocated = false;
1749 struct ulist_iterator uiter;
1752 ASSERT(ctx->refs == NULL);
1754 ctx->refs = ulist_alloc(GFP_NOFS);
1759 ctx->roots = ulist_alloc(GFP_NOFS);
1761 ulist_free(ctx->refs);
1765 roots_ulist_allocated = true;
1768 ctx->skip_inode_ref_list = true;
1770 ULIST_ITER_INIT(&uiter);
1772 struct ulist_node *node;
1774 ret = find_parent_nodes(ctx, NULL);
1775 if (ret < 0 && ret != -ENOENT) {
1776 if (roots_ulist_allocated) {
1777 ulist_free(ctx->roots);
1783 node = ulist_next(ctx->refs, &uiter);
1786 ctx->bytenr = node->val;
1790 ulist_free(ctx->refs);
1792 ctx->bytenr = orig_bytenr;
1793 ctx->skip_inode_ref_list = orig_skip_inode_ref_list;
1798 int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx,
1799 bool skip_commit_root_sem)
1803 if (!ctx->trans && !skip_commit_root_sem)
1804 down_read(&ctx->fs_info->commit_root_sem);
1805 ret = btrfs_find_all_roots_safe(ctx);
1806 if (!ctx->trans && !skip_commit_root_sem)
1807 up_read(&ctx->fs_info->commit_root_sem);
1811 struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void)
1813 struct btrfs_backref_share_check_ctx *ctx;
1815 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
1819 ulist_init(&ctx->refs);
1824 void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx)
1829 ulist_release(&ctx->refs);
1834 * Check if a data extent is shared or not.
1836 * @inode: The inode whose extent we are checking.
1837 * @bytenr: Logical bytenr of the extent we are checking.
1838 * @extent_gen: Generation of the extent (file extent item) or 0 if it is
1840 * @ctx: A backref sharedness check context.
1842 * btrfs_is_data_extent_shared uses the backref walking code but will short
1843 * circuit as soon as it finds a root or inode that doesn't match the
1844 * one passed in. This provides a significant performance benefit for
1845 * callers (such as fiemap) which want to know whether the extent is
1846 * shared but do not need a ref count.
1848 * This attempts to attach to the running transaction in order to account for
1849 * delayed refs, but continues on even when no running transaction exists.
1851 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1853 int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,
1855 struct btrfs_backref_share_check_ctx *ctx)
1857 struct btrfs_backref_walk_ctx walk_ctx = { 0 };
1858 struct btrfs_root *root = inode->root;
1859 struct btrfs_fs_info *fs_info = root->fs_info;
1860 struct btrfs_trans_handle *trans;
1861 struct ulist_iterator uiter;
1862 struct ulist_node *node;
1863 struct btrfs_seq_list elem = BTRFS_SEQ_LIST_INIT(elem);
1865 struct share_check shared = {
1868 .inum = btrfs_ino(inode),
1869 .data_bytenr = bytenr,
1870 .data_extent_gen = extent_gen,
1872 .self_ref_count = 0,
1873 .have_delayed_delete_refs = false,
1877 bool leaf_is_shared;
1879 for (int i = 0; i < BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE; i++) {
1880 if (ctx->prev_extents_cache[i].bytenr == bytenr)
1881 return ctx->prev_extents_cache[i].is_shared;
1884 ulist_init(&ctx->refs);
1886 trans = btrfs_join_transaction_nostart(root);
1887 if (IS_ERR(trans)) {
1888 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
1889 ret = PTR_ERR(trans);
1893 down_read(&fs_info->commit_root_sem);
1895 btrfs_get_tree_mod_seq(fs_info, &elem);
1896 walk_ctx.time_seq = elem.seq;
1899 ctx->use_path_cache = true;
1902 * We may have previously determined that the current leaf is shared.
1903 * If it is, then we have a data extent that is shared due to a shared
1904 * subtree (caused by snapshotting) and we don't need to check for data
1905 * backrefs. If the leaf is not shared, then we must do backref walking
1906 * to determine if the data extent is shared through reflinks.
1908 leaf_cached = lookup_backref_shared_cache(ctx, root,
1909 ctx->curr_leaf_bytenr, 0,
1911 if (leaf_cached && leaf_is_shared) {
1916 walk_ctx.skip_inode_ref_list = true;
1917 walk_ctx.trans = trans;
1918 walk_ctx.fs_info = fs_info;
1919 walk_ctx.refs = &ctx->refs;
1921 /* -1 means we are in the bytenr of the data extent. */
1923 ULIST_ITER_INIT(&uiter);
1925 const unsigned long prev_ref_count = ctx->refs.nnodes;
1927 walk_ctx.bytenr = bytenr;
1928 ret = find_parent_nodes(&walk_ctx, &shared);
1929 if (ret == BACKREF_FOUND_SHARED ||
1930 ret == BACKREF_FOUND_NOT_SHARED) {
1931 /* If shared must return 1, otherwise return 0. */
1932 ret = (ret == BACKREF_FOUND_SHARED) ? 1 : 0;
1934 store_backref_shared_cache(ctx, root, bytenr,
1938 if (ret < 0 && ret != -ENOENT)
1943 * More than one extent buffer (bytenr) may have been added to
1944 * the ctx->refs ulist, in which case we have to check multiple
1945 * tree paths in case the first one is not shared, so we can not
1946 * use the path cache which is made for a single path. Multiple
1947 * extent buffers at the current level happen when:
1949 * 1) level -1, the data extent: If our data extent was not
1950 * directly shared (without multiple reference items), then
1951 * it might have a single reference item with a count > 1 for
1952 * the same offset, which means there are 2 (or more) file
1953 * extent items that point to the data extent - this happens
1954 * when a file extent item needs to be split and then one
1955 * item gets moved to another leaf due to a b+tree leaf split
1956 * when inserting some item. In this case the file extent
1957 * items may be located in different leaves and therefore
1958 * some of the leaves may be referenced through shared
1959 * subtrees while others are not. Since our extent buffer
1960 * cache only works for a single path (by far the most common
1961 * case and simpler to deal with), we can not use it if we
1962 * have multiple leaves (which implies multiple paths).
1964 * 2) level >= 0, a tree node/leaf: We can have a mix of direct
1965 * and indirect references on a b+tree node/leaf, so we have
1966 * to check multiple paths, and the extent buffer (the
1967 * current bytenr) may be shared or not. One example is
1968 * during relocation as we may get a shared tree block ref
1969 * (direct ref) and a non-shared tree block ref (indirect
1970 * ref) for the same node/leaf.
1972 if ((ctx->refs.nnodes - prev_ref_count) > 1)
1973 ctx->use_path_cache = false;
1976 store_backref_shared_cache(ctx, root, bytenr,
1978 node = ulist_next(&ctx->refs, &uiter);
1982 if (ctx->use_path_cache) {
1987 cached = lookup_backref_shared_cache(ctx, root, bytenr,
1990 ret = (is_shared ? 1 : 0);
1994 shared.share_count = 0;
1995 shared.have_delayed_delete_refs = false;
2000 * If the path cache is disabled, then it means at some tree level we
2001 * got multiple parents due to a mix of direct and indirect backrefs or
2002 * multiple leaves with file extent items pointing to the same data
2003 * extent. We have to invalidate the cache and cache only the sharedness
2004 * result for the levels where we got only one node/reference.
2006 if (!ctx->use_path_cache) {
2010 if (ret >= 0 && level >= 0) {
2011 bytenr = ctx->path_cache_entries[level].bytenr;
2012 ctx->use_path_cache = true;
2013 store_backref_shared_cache(ctx, root, bytenr, level, ret);
2017 for ( ; i < BTRFS_MAX_LEVEL; i++)
2018 ctx->path_cache_entries[i].bytenr = 0;
2022 * Cache the sharedness result for the data extent if we know our inode
2023 * has more than 1 file extent item that refers to the data extent.
2025 if (ret >= 0 && shared.self_ref_count > 1) {
2026 int slot = ctx->prev_extents_cache_slot;
2028 ctx->prev_extents_cache[slot].bytenr = shared.data_bytenr;
2029 ctx->prev_extents_cache[slot].is_shared = (ret == 1);
2031 slot = (slot + 1) % BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE;
2032 ctx->prev_extents_cache_slot = slot;
2037 btrfs_put_tree_mod_seq(fs_info, &elem);
2038 btrfs_end_transaction(trans);
2040 up_read(&fs_info->commit_root_sem);
2043 ulist_release(&ctx->refs);
2044 ctx->prev_leaf_bytenr = ctx->curr_leaf_bytenr;
2049 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
2050 u64 start_off, struct btrfs_path *path,
2051 struct btrfs_inode_extref **ret_extref,
2055 struct btrfs_key key;
2056 struct btrfs_key found_key;
2057 struct btrfs_inode_extref *extref;
2058 const struct extent_buffer *leaf;
2061 key.objectid = inode_objectid;
2062 key.type = BTRFS_INODE_EXTREF_KEY;
2063 key.offset = start_off;
2065 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2070 leaf = path->nodes[0];
2071 slot = path->slots[0];
2072 if (slot >= btrfs_header_nritems(leaf)) {
2074 * If the item at offset is not found,
2075 * btrfs_search_slot will point us to the slot
2076 * where it should be inserted. In our case
2077 * that will be the slot directly before the
2078 * next INODE_REF_KEY_V2 item. In the case
2079 * that we're pointing to the last slot in a
2080 * leaf, we must move one leaf over.
2082 ret = btrfs_next_leaf(root, path);
2091 btrfs_item_key_to_cpu(leaf, &found_key, slot);
2094 * Check that we're still looking at an extended ref key for
2095 * this particular objectid. If we have different
2096 * objectid or type then there are no more to be found
2097 * in the tree and we can exit.
2100 if (found_key.objectid != inode_objectid)
2102 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
2106 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2107 extref = (struct btrfs_inode_extref *)ptr;
2108 *ret_extref = extref;
2110 *found_off = found_key.offset;
2118 * this iterates to turn a name (from iref/extref) into a full filesystem path.
2119 * Elements of the path are separated by '/' and the path is guaranteed to be
2120 * 0-terminated. the path is only given within the current file system.
2121 * Therefore, it never starts with a '/'. the caller is responsible to provide
2122 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
2123 * the start point of the resulting string is returned. this pointer is within
2125 * in case the path buffer would overflow, the pointer is decremented further
2126 * as if output was written to the buffer, though no more output is actually
2127 * generated. that way, the caller can determine how much space would be
2128 * required for the path to fit into the buffer. in that case, the returned
2129 * value will be smaller than dest. callers must check this!
2131 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
2132 u32 name_len, unsigned long name_off,
2133 struct extent_buffer *eb_in, u64 parent,
2134 char *dest, u32 size)
2139 s64 bytes_left = ((s64)size) - 1;
2140 struct extent_buffer *eb = eb_in;
2141 struct btrfs_key found_key;
2142 struct btrfs_inode_ref *iref;
2144 if (bytes_left >= 0)
2145 dest[bytes_left] = '\0';
2148 bytes_left -= name_len;
2149 if (bytes_left >= 0)
2150 read_extent_buffer(eb, dest + bytes_left,
2151 name_off, name_len);
2153 if (!path->skip_locking)
2154 btrfs_tree_read_unlock(eb);
2155 free_extent_buffer(eb);
2157 ret = btrfs_find_item(fs_root, path, parent, 0,
2158 BTRFS_INODE_REF_KEY, &found_key);
2164 next_inum = found_key.offset;
2166 /* regular exit ahead */
2167 if (parent == next_inum)
2170 slot = path->slots[0];
2171 eb = path->nodes[0];
2172 /* make sure we can use eb after releasing the path */
2174 path->nodes[0] = NULL;
2177 btrfs_release_path(path);
2178 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2180 name_len = btrfs_inode_ref_name_len(eb, iref);
2181 name_off = (unsigned long)(iref + 1);
2185 if (bytes_left >= 0)
2186 dest[bytes_left] = '/';
2189 btrfs_release_path(path);
2192 return ERR_PTR(ret);
2194 return dest + bytes_left;
2198 * this makes the path point to (logical EXTENT_ITEM *)
2199 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
2200 * tree blocks and <0 on error.
2202 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
2203 struct btrfs_path *path, struct btrfs_key *found_key,
2206 struct btrfs_root *extent_root = btrfs_extent_root(fs_info, logical);
2211 const struct extent_buffer *eb;
2212 struct btrfs_extent_item *ei;
2213 struct btrfs_key key;
2215 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2216 key.type = BTRFS_METADATA_ITEM_KEY;
2218 key.type = BTRFS_EXTENT_ITEM_KEY;
2219 key.objectid = logical;
2220 key.offset = (u64)-1;
2222 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
2227 * Key with offset -1 found, there would have to exist an extent
2228 * item with such offset, but this is out of the valid range.
2233 ret = btrfs_previous_extent_item(extent_root, path, 0);
2239 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
2240 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
2241 size = fs_info->nodesize;
2242 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
2243 size = found_key->offset;
2245 if (found_key->objectid > logical ||
2246 found_key->objectid + size <= logical) {
2247 btrfs_debug(fs_info,
2248 "logical %llu is not within any extent", logical);
2252 eb = path->nodes[0];
2253 item_size = btrfs_item_size(eb, path->slots[0]);
2255 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
2256 flags = btrfs_extent_flags(eb, ei);
2258 btrfs_debug(fs_info,
2259 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
2260 logical, logical - found_key->objectid, found_key->objectid,
2261 found_key->offset, flags, item_size);
2263 WARN_ON(!flags_ret);
2265 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2266 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
2267 else if (flags & BTRFS_EXTENT_FLAG_DATA)
2268 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
2278 * helper function to iterate extent inline refs. ptr must point to a 0 value
2279 * for the first call and may be modified. it is used to track state.
2280 * if more refs exist, 0 is returned and the next call to
2281 * get_extent_inline_ref must pass the modified ptr parameter to get the
2282 * next ref. after the last ref was processed, 1 is returned.
2283 * returns <0 on error
2285 static int get_extent_inline_ref(unsigned long *ptr,
2286 const struct extent_buffer *eb,
2287 const struct btrfs_key *key,
2288 const struct btrfs_extent_item *ei,
2290 struct btrfs_extent_inline_ref **out_eiref,
2295 struct btrfs_tree_block_info *info;
2299 flags = btrfs_extent_flags(eb, ei);
2300 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2301 if (key->type == BTRFS_METADATA_ITEM_KEY) {
2302 /* a skinny metadata extent */
2304 (struct btrfs_extent_inline_ref *)(ei + 1);
2306 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
2307 info = (struct btrfs_tree_block_info *)(ei + 1);
2309 (struct btrfs_extent_inline_ref *)(info + 1);
2312 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
2314 *ptr = (unsigned long)*out_eiref;
2315 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
2319 end = (unsigned long)ei + item_size;
2320 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
2321 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
2322 BTRFS_REF_TYPE_ANY);
2323 if (*out_type == BTRFS_REF_TYPE_INVALID)
2326 *ptr += btrfs_extent_inline_ref_size(*out_type);
2327 WARN_ON(*ptr > end);
2329 return 1; /* last */
2335 * reads the tree block backref for an extent. tree level and root are returned
2336 * through out_level and out_root. ptr must point to a 0 value for the first
2337 * call and may be modified (see get_extent_inline_ref comment).
2338 * returns 0 if data was provided, 1 if there was no more data to provide or
2341 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
2342 struct btrfs_key *key, struct btrfs_extent_item *ei,
2343 u32 item_size, u64 *out_root, u8 *out_level)
2347 struct btrfs_extent_inline_ref *eiref;
2349 if (*ptr == (unsigned long)-1)
2353 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
2358 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
2359 type == BTRFS_SHARED_BLOCK_REF_KEY)
2366 /* we can treat both ref types equally here */
2367 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
2369 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
2370 struct btrfs_tree_block_info *info;
2372 info = (struct btrfs_tree_block_info *)(ei + 1);
2373 *out_level = btrfs_tree_block_level(eb, info);
2375 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
2376 *out_level = (u8)key->offset;
2380 *ptr = (unsigned long)-1;
2385 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
2386 struct extent_inode_elem *inode_list,
2387 u64 root, u64 extent_item_objectid,
2388 iterate_extent_inodes_t *iterate, void *ctx)
2390 struct extent_inode_elem *eie;
2393 for (eie = inode_list; eie; eie = eie->next) {
2394 btrfs_debug(fs_info,
2395 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
2396 extent_item_objectid, eie->inum,
2398 ret = iterate(eie->inum, eie->offset, eie->num_bytes, root, ctx);
2400 btrfs_debug(fs_info,
2401 "stopping iteration for %llu due to ret=%d",
2402 extent_item_objectid, ret);
2411 * calls iterate() for every inode that references the extent identified by
2412 * the given parameters.
2413 * when the iterator function returns a non-zero value, iteration stops.
2415 int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx,
2416 bool search_commit_root,
2417 iterate_extent_inodes_t *iterate, void *user_ctx)
2421 struct ulist_node *ref_node;
2422 struct btrfs_seq_list seq_elem = BTRFS_SEQ_LIST_INIT(seq_elem);
2423 struct ulist_iterator ref_uiter;
2425 btrfs_debug(ctx->fs_info, "resolving all inodes for extent %llu",
2428 ASSERT(ctx->trans == NULL);
2429 ASSERT(ctx->roots == NULL);
2431 if (!search_commit_root) {
2432 struct btrfs_trans_handle *trans;
2434 trans = btrfs_attach_transaction(ctx->fs_info->tree_root);
2435 if (IS_ERR(trans)) {
2436 if (PTR_ERR(trans) != -ENOENT &&
2437 PTR_ERR(trans) != -EROFS)
2438 return PTR_ERR(trans);
2445 btrfs_get_tree_mod_seq(ctx->fs_info, &seq_elem);
2446 ctx->time_seq = seq_elem.seq;
2448 down_read(&ctx->fs_info->commit_root_sem);
2451 ret = btrfs_find_all_leafs(ctx);
2457 ULIST_ITER_INIT(&ref_uiter);
2458 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
2459 const u64 leaf_bytenr = ref_node->val;
2460 struct ulist_node *root_node;
2461 struct ulist_iterator root_uiter;
2462 struct extent_inode_elem *inode_list;
2464 inode_list = (struct extent_inode_elem *)(uintptr_t)ref_node->aux;
2466 if (ctx->cache_lookup) {
2467 const u64 *root_ids;
2471 cached = ctx->cache_lookup(leaf_bytenr, ctx->user_ctx,
2472 &root_ids, &root_count);
2474 for (int i = 0; i < root_count; i++) {
2475 ret = iterate_leaf_refs(ctx->fs_info,
2489 ctx->roots = ulist_alloc(GFP_NOFS);
2496 ctx->bytenr = leaf_bytenr;
2497 ret = btrfs_find_all_roots_safe(ctx);
2501 if (ctx->cache_store)
2502 ctx->cache_store(leaf_bytenr, ctx->roots, ctx->user_ctx);
2504 ULIST_ITER_INIT(&root_uiter);
2505 while (!ret && (root_node = ulist_next(ctx->roots, &root_uiter))) {
2506 btrfs_debug(ctx->fs_info,
2507 "root %llu references leaf %llu, data list %#llx",
2508 root_node->val, ref_node->val,
2510 ret = iterate_leaf_refs(ctx->fs_info, inode_list,
2511 root_node->val, ctx->bytenr,
2514 ulist_reinit(ctx->roots);
2517 free_leaf_list(refs);
2520 btrfs_put_tree_mod_seq(ctx->fs_info, &seq_elem);
2521 btrfs_end_transaction(ctx->trans);
2524 up_read(&ctx->fs_info->commit_root_sem);
2527 ulist_free(ctx->roots);
2530 if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP)
2536 static int build_ino_list(u64 inum, u64 offset, u64 num_bytes, u64 root, void *ctx)
2538 struct btrfs_data_container *inodes = ctx;
2539 const size_t c = 3 * sizeof(u64);
2541 if (inodes->bytes_left >= c) {
2542 inodes->bytes_left -= c;
2543 inodes->val[inodes->elem_cnt] = inum;
2544 inodes->val[inodes->elem_cnt + 1] = offset;
2545 inodes->val[inodes->elem_cnt + 2] = root;
2546 inodes->elem_cnt += 3;
2548 inodes->bytes_missing += c - inodes->bytes_left;
2549 inodes->bytes_left = 0;
2550 inodes->elem_missed += 3;
2556 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
2557 struct btrfs_path *path,
2558 void *ctx, bool ignore_offset)
2560 struct btrfs_backref_walk_ctx walk_ctx = { 0 };
2563 struct btrfs_key found_key;
2564 int search_commit_root = path->search_commit_root;
2566 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
2567 btrfs_release_path(path);
2570 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2573 walk_ctx.bytenr = found_key.objectid;
2575 walk_ctx.ignore_extent_item_pos = true;
2577 walk_ctx.extent_item_pos = logical - found_key.objectid;
2578 walk_ctx.fs_info = fs_info;
2580 return iterate_extent_inodes(&walk_ctx, search_commit_root,
2581 build_ino_list, ctx);
2584 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2585 struct extent_buffer *eb, struct inode_fs_paths *ipath);
2587 static int iterate_inode_refs(u64 inum, struct inode_fs_paths *ipath)
2596 struct btrfs_root *fs_root = ipath->fs_root;
2597 struct btrfs_path *path = ipath->btrfs_path;
2598 struct extent_buffer *eb;
2599 struct btrfs_inode_ref *iref;
2600 struct btrfs_key found_key;
2603 ret = btrfs_find_item(fs_root, path, inum,
2604 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2610 ret = found ? 0 : -ENOENT;
2615 parent = found_key.offset;
2616 slot = path->slots[0];
2617 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2622 btrfs_release_path(path);
2624 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2626 for (cur = 0; cur < btrfs_item_size(eb, slot); cur += len) {
2627 name_len = btrfs_inode_ref_name_len(eb, iref);
2628 /* path must be released before calling iterate()! */
2629 btrfs_debug(fs_root->fs_info,
2630 "following ref at offset %u for inode %llu in tree %llu",
2631 cur, found_key.objectid,
2632 fs_root->root_key.objectid);
2633 ret = inode_to_path(parent, name_len,
2634 (unsigned long)(iref + 1), eb, ipath);
2637 len = sizeof(*iref) + name_len;
2638 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2640 free_extent_buffer(eb);
2643 btrfs_release_path(path);
2648 static int iterate_inode_extrefs(u64 inum, struct inode_fs_paths *ipath)
2655 struct btrfs_root *fs_root = ipath->fs_root;
2656 struct btrfs_path *path = ipath->btrfs_path;
2657 struct extent_buffer *eb;
2658 struct btrfs_inode_extref *extref;
2664 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2669 ret = found ? 0 : -ENOENT;
2674 slot = path->slots[0];
2675 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2680 btrfs_release_path(path);
2682 item_size = btrfs_item_size(eb, slot);
2683 ptr = btrfs_item_ptr_offset(eb, slot);
2686 while (cur_offset < item_size) {
2689 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2690 parent = btrfs_inode_extref_parent(eb, extref);
2691 name_len = btrfs_inode_extref_name_len(eb, extref);
2692 ret = inode_to_path(parent, name_len,
2693 (unsigned long)&extref->name, eb, ipath);
2697 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2698 cur_offset += sizeof(*extref);
2700 free_extent_buffer(eb);
2705 btrfs_release_path(path);
2711 * returns 0 if the path could be dumped (probably truncated)
2712 * returns <0 in case of an error
2714 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2715 struct extent_buffer *eb, struct inode_fs_paths *ipath)
2719 int i = ipath->fspath->elem_cnt;
2720 const int s_ptr = sizeof(char *);
2723 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2724 ipath->fspath->bytes_left - s_ptr : 0;
2726 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2727 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2728 name_off, eb, inum, fspath_min, bytes_left);
2730 return PTR_ERR(fspath);
2732 if (fspath > fspath_min) {
2733 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2734 ++ipath->fspath->elem_cnt;
2735 ipath->fspath->bytes_left = fspath - fspath_min;
2737 ++ipath->fspath->elem_missed;
2738 ipath->fspath->bytes_missing += fspath_min - fspath;
2739 ipath->fspath->bytes_left = 0;
2746 * this dumps all file system paths to the inode into the ipath struct, provided
2747 * is has been created large enough. each path is zero-terminated and accessed
2748 * from ipath->fspath->val[i].
2749 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2750 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2751 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2752 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2753 * have been needed to return all paths.
2755 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2760 ret = iterate_inode_refs(inum, ipath);
2763 else if (ret != -ENOENT)
2766 ret = iterate_inode_extrefs(inum, ipath);
2767 if (ret == -ENOENT && found_refs)
2773 struct btrfs_data_container *init_data_container(u32 total_bytes)
2775 struct btrfs_data_container *data;
2778 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2779 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2781 return ERR_PTR(-ENOMEM);
2783 if (total_bytes >= sizeof(*data)) {
2784 data->bytes_left = total_bytes - sizeof(*data);
2785 data->bytes_missing = 0;
2787 data->bytes_missing = sizeof(*data) - total_bytes;
2788 data->bytes_left = 0;
2792 data->elem_missed = 0;
2798 * allocates space to return multiple file system paths for an inode.
2799 * total_bytes to allocate are passed, note that space usable for actual path
2800 * information will be total_bytes - sizeof(struct inode_fs_paths).
2801 * the returned pointer must be freed with free_ipath() in the end.
2803 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2804 struct btrfs_path *path)
2806 struct inode_fs_paths *ifp;
2807 struct btrfs_data_container *fspath;
2809 fspath = init_data_container(total_bytes);
2811 return ERR_CAST(fspath);
2813 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2816 return ERR_PTR(-ENOMEM);
2819 ifp->btrfs_path = path;
2820 ifp->fspath = fspath;
2821 ifp->fs_root = fs_root;
2826 void free_ipath(struct inode_fs_paths *ipath)
2830 kvfree(ipath->fspath);
2834 struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info)
2836 struct btrfs_backref_iter *ret;
2838 ret = kzalloc(sizeof(*ret), GFP_NOFS);
2842 ret->path = btrfs_alloc_path();
2848 /* Current backref iterator only supports iteration in commit root */
2849 ret->path->search_commit_root = 1;
2850 ret->path->skip_locking = 1;
2851 ret->fs_info = fs_info;
2856 static void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
2862 btrfs_release_path(iter->path);
2863 memset(&iter->cur_key, 0, sizeof(iter->cur_key));
2866 int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr)
2868 struct btrfs_fs_info *fs_info = iter->fs_info;
2869 struct btrfs_root *extent_root = btrfs_extent_root(fs_info, bytenr);
2870 struct btrfs_path *path = iter->path;
2871 struct btrfs_extent_item *ei;
2872 struct btrfs_key key;
2875 key.objectid = bytenr;
2876 key.type = BTRFS_METADATA_ITEM_KEY;
2877 key.offset = (u64)-1;
2878 iter->bytenr = bytenr;
2880 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
2885 * Key with offset -1 found, there would have to exist an extent
2886 * item with such offset, but this is out of the valid range.
2891 if (path->slots[0] == 0) {
2892 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
2898 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
2899 if ((key.type != BTRFS_EXTENT_ITEM_KEY &&
2900 key.type != BTRFS_METADATA_ITEM_KEY) || key.objectid != bytenr) {
2904 memcpy(&iter->cur_key, &key, sizeof(key));
2905 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2907 iter->end_ptr = (u32)(iter->item_ptr +
2908 btrfs_item_size(path->nodes[0], path->slots[0]));
2909 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
2910 struct btrfs_extent_item);
2913 * Only support iteration on tree backref yet.
2915 * This is an extra precaution for non skinny-metadata, where
2916 * EXTENT_ITEM is also used for tree blocks, that we can only use
2917 * extent flags to determine if it's a tree block.
2919 if (btrfs_extent_flags(path->nodes[0], ei) & BTRFS_EXTENT_FLAG_DATA) {
2923 iter->cur_ptr = (u32)(iter->item_ptr + sizeof(*ei));
2925 /* If there is no inline backref, go search for keyed backref */
2926 if (iter->cur_ptr >= iter->end_ptr) {
2927 ret = btrfs_next_item(extent_root, path);
2929 /* No inline nor keyed ref */
2937 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key,
2939 if (iter->cur_key.objectid != bytenr ||
2940 (iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY &&
2941 iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY)) {
2945 iter->cur_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2947 iter->item_ptr = iter->cur_ptr;
2948 iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size(
2949 path->nodes[0], path->slots[0]));
2954 btrfs_backref_iter_release(iter);
2958 static bool btrfs_backref_iter_is_inline_ref(struct btrfs_backref_iter *iter)
2960 if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY ||
2961 iter->cur_key.type == BTRFS_METADATA_ITEM_KEY)
2967 * Go to the next backref item of current bytenr, can be either inlined or
2970 * Caller needs to check whether it's inline ref or not by iter->cur_key.
2972 * Return 0 if we get next backref without problem.
2973 * Return >0 if there is no extra backref for this bytenr.
2974 * Return <0 if there is something wrong happened.
2976 int btrfs_backref_iter_next(struct btrfs_backref_iter *iter)
2978 struct extent_buffer *eb = iter->path->nodes[0];
2979 struct btrfs_root *extent_root;
2980 struct btrfs_path *path = iter->path;
2981 struct btrfs_extent_inline_ref *iref;
2985 if (btrfs_backref_iter_is_inline_ref(iter)) {
2986 /* We're still inside the inline refs */
2987 ASSERT(iter->cur_ptr < iter->end_ptr);
2989 if (btrfs_backref_has_tree_block_info(iter)) {
2990 /* First tree block info */
2991 size = sizeof(struct btrfs_tree_block_info);
2993 /* Use inline ref type to determine the size */
2996 iref = (struct btrfs_extent_inline_ref *)
2997 ((unsigned long)iter->cur_ptr);
2998 type = btrfs_extent_inline_ref_type(eb, iref);
3000 size = btrfs_extent_inline_ref_size(type);
3002 iter->cur_ptr += size;
3003 if (iter->cur_ptr < iter->end_ptr)
3006 /* All inline items iterated, fall through */
3009 /* We're at keyed items, there is no inline item, go to the next one */
3010 extent_root = btrfs_extent_root(iter->fs_info, iter->bytenr);
3011 ret = btrfs_next_item(extent_root, iter->path);
3015 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]);
3016 if (iter->cur_key.objectid != iter->bytenr ||
3017 (iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY &&
3018 iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY))
3020 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
3022 iter->cur_ptr = iter->item_ptr;
3023 iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size(path->nodes[0],
3028 void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
3029 struct btrfs_backref_cache *cache, bool is_reloc)
3033 cache->rb_root = RB_ROOT;
3034 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
3035 INIT_LIST_HEAD(&cache->pending[i]);
3036 INIT_LIST_HEAD(&cache->changed);
3037 INIT_LIST_HEAD(&cache->detached);
3038 INIT_LIST_HEAD(&cache->leaves);
3039 INIT_LIST_HEAD(&cache->pending_edge);
3040 INIT_LIST_HEAD(&cache->useless_node);
3041 cache->fs_info = fs_info;
3042 cache->is_reloc = is_reloc;
3045 struct btrfs_backref_node *btrfs_backref_alloc_node(
3046 struct btrfs_backref_cache *cache, u64 bytenr, int level)
3048 struct btrfs_backref_node *node;
3050 ASSERT(level >= 0 && level < BTRFS_MAX_LEVEL);
3051 node = kzalloc(sizeof(*node), GFP_NOFS);
3055 INIT_LIST_HEAD(&node->list);
3056 INIT_LIST_HEAD(&node->upper);
3057 INIT_LIST_HEAD(&node->lower);
3058 RB_CLEAR_NODE(&node->rb_node);
3060 node->level = level;
3061 node->bytenr = bytenr;
3066 void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
3067 struct btrfs_backref_node *node)
3070 ASSERT(list_empty(&node->list));
3071 ASSERT(list_empty(&node->lower));
3072 ASSERT(node->eb == NULL);
3074 btrfs_put_root(node->root);
3079 struct btrfs_backref_edge *btrfs_backref_alloc_edge(
3080 struct btrfs_backref_cache *cache)
3082 struct btrfs_backref_edge *edge;
3084 edge = kzalloc(sizeof(*edge), GFP_NOFS);
3090 void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
3091 struct btrfs_backref_edge *edge)
3099 void btrfs_backref_unlock_node_buffer(struct btrfs_backref_node *node)
3102 btrfs_tree_unlock(node->eb);
3107 void btrfs_backref_drop_node_buffer(struct btrfs_backref_node *node)
3110 btrfs_backref_unlock_node_buffer(node);
3111 free_extent_buffer(node->eb);
3117 * Drop the backref node from cache without cleaning up its children
3120 * This can only be called on node without parent edges.
3121 * The children edges are still kept as is.
3123 void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
3124 struct btrfs_backref_node *node)
3126 ASSERT(list_empty(&node->upper));
3128 btrfs_backref_drop_node_buffer(node);
3129 list_del_init(&node->list);
3130 list_del_init(&node->lower);
3131 if (!RB_EMPTY_NODE(&node->rb_node))
3132 rb_erase(&node->rb_node, &tree->rb_root);
3133 btrfs_backref_free_node(tree, node);
3137 * Drop the backref node from cache, also cleaning up all its
3138 * upper edges and any uncached nodes in the path.
3140 * This cleanup happens bottom up, thus the node should either
3141 * be the lowest node in the cache or a detached node.
3143 void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
3144 struct btrfs_backref_node *node)
3146 struct btrfs_backref_node *upper;
3147 struct btrfs_backref_edge *edge;
3152 BUG_ON(!node->lowest && !node->detached);
3153 while (!list_empty(&node->upper)) {
3154 edge = list_entry(node->upper.next, struct btrfs_backref_edge,
3156 upper = edge->node[UPPER];
3157 list_del(&edge->list[LOWER]);
3158 list_del(&edge->list[UPPER]);
3159 btrfs_backref_free_edge(cache, edge);
3162 * Add the node to leaf node list if no other child block
3165 if (list_empty(&upper->lower)) {
3166 list_add_tail(&upper->lower, &cache->leaves);
3171 btrfs_backref_drop_node(cache, node);
3175 * Release all nodes/edges from current cache
3177 void btrfs_backref_release_cache(struct btrfs_backref_cache *cache)
3179 struct btrfs_backref_node *node;
3182 while (!list_empty(&cache->detached)) {
3183 node = list_entry(cache->detached.next,
3184 struct btrfs_backref_node, list);
3185 btrfs_backref_cleanup_node(cache, node);
3188 while (!list_empty(&cache->leaves)) {
3189 node = list_entry(cache->leaves.next,
3190 struct btrfs_backref_node, lower);
3191 btrfs_backref_cleanup_node(cache, node);
3194 cache->last_trans = 0;
3196 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
3197 ASSERT(list_empty(&cache->pending[i]));
3198 ASSERT(list_empty(&cache->pending_edge));
3199 ASSERT(list_empty(&cache->useless_node));
3200 ASSERT(list_empty(&cache->changed));
3201 ASSERT(list_empty(&cache->detached));
3202 ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
3203 ASSERT(!cache->nr_nodes);
3204 ASSERT(!cache->nr_edges);
3207 void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
3208 struct btrfs_backref_node *lower,
3209 struct btrfs_backref_node *upper,
3212 ASSERT(upper && lower && upper->level == lower->level + 1);
3213 edge->node[LOWER] = lower;
3214 edge->node[UPPER] = upper;
3215 if (link_which & LINK_LOWER)
3216 list_add_tail(&edge->list[LOWER], &lower->upper);
3217 if (link_which & LINK_UPPER)
3218 list_add_tail(&edge->list[UPPER], &upper->lower);
3221 * Handle direct tree backref
3223 * Direct tree backref means, the backref item shows its parent bytenr
3224 * directly. This is for SHARED_BLOCK_REF backref (keyed or inlined).
3226 * @ref_key: The converted backref key.
3227 * For keyed backref, it's the item key.
3228 * For inlined backref, objectid is the bytenr,
3229 * type is btrfs_inline_ref_type, offset is
3230 * btrfs_inline_ref_offset.
3232 static int handle_direct_tree_backref(struct btrfs_backref_cache *cache,
3233 struct btrfs_key *ref_key,
3234 struct btrfs_backref_node *cur)
3236 struct btrfs_backref_edge *edge;
3237 struct btrfs_backref_node *upper;
3238 struct rb_node *rb_node;
3240 ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY);
3242 /* Only reloc root uses backref pointing to itself */
3243 if (ref_key->objectid == ref_key->offset) {
3244 struct btrfs_root *root;
3246 cur->is_reloc_root = 1;
3247 /* Only reloc backref cache cares about a specific root */
3248 if (cache->is_reloc) {
3249 root = find_reloc_root(cache->fs_info, cur->bytenr);
3255 * For generic purpose backref cache, reloc root node
3258 list_add(&cur->list, &cache->useless_node);
3263 edge = btrfs_backref_alloc_edge(cache);
3267 rb_node = rb_simple_search(&cache->rb_root, ref_key->offset);
3269 /* Parent node not yet cached */
3270 upper = btrfs_backref_alloc_node(cache, ref_key->offset,
3273 btrfs_backref_free_edge(cache, edge);
3278 * Backrefs for the upper level block isn't cached, add the
3279 * block to pending list
3281 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
3283 /* Parent node already cached */
3284 upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
3285 ASSERT(upper->checked);
3286 INIT_LIST_HEAD(&edge->list[UPPER]);
3288 btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER);
3293 * Handle indirect tree backref
3295 * Indirect tree backref means, we only know which tree the node belongs to.
3296 * We still need to do a tree search to find out the parents. This is for
3297 * TREE_BLOCK_REF backref (keyed or inlined).
3299 * @trans: Transaction handle.
3300 * @ref_key: The same as @ref_key in handle_direct_tree_backref()
3301 * @tree_key: The first key of this tree block.
3302 * @path: A clean (released) path, to avoid allocating path every time
3303 * the function get called.
3305 static int handle_indirect_tree_backref(struct btrfs_trans_handle *trans,
3306 struct btrfs_backref_cache *cache,
3307 struct btrfs_path *path,
3308 struct btrfs_key *ref_key,
3309 struct btrfs_key *tree_key,
3310 struct btrfs_backref_node *cur)
3312 struct btrfs_fs_info *fs_info = cache->fs_info;
3313 struct btrfs_backref_node *upper;
3314 struct btrfs_backref_node *lower;
3315 struct btrfs_backref_edge *edge;
3316 struct extent_buffer *eb;
3317 struct btrfs_root *root;
3318 struct rb_node *rb_node;
3320 bool need_check = true;
3323 root = btrfs_get_fs_root(fs_info, ref_key->offset, false);
3325 return PTR_ERR(root);
3326 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
3329 if (btrfs_root_level(&root->root_item) == cur->level) {
3331 ASSERT(btrfs_root_bytenr(&root->root_item) == cur->bytenr);
3333 * For reloc backref cache, we may ignore reloc root. But for
3334 * general purpose backref cache, we can't rely on
3335 * btrfs_should_ignore_reloc_root() as it may conflict with
3336 * current running relocation and lead to missing root.
3338 * For general purpose backref cache, reloc root detection is
3339 * completely relying on direct backref (key->offset is parent
3340 * bytenr), thus only do such check for reloc cache.
3342 if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) {
3343 btrfs_put_root(root);
3344 list_add(&cur->list, &cache->useless_node);
3351 level = cur->level + 1;
3353 /* Search the tree to find parent blocks referring to the block */
3354 path->search_commit_root = 1;
3355 path->skip_locking = 1;
3356 path->lowest_level = level;
3357 ret = btrfs_search_slot(NULL, root, tree_key, path, 0, 0);
3358 path->lowest_level = 0;
3360 btrfs_put_root(root);
3363 if (ret > 0 && path->slots[level] > 0)
3364 path->slots[level]--;
3366 eb = path->nodes[level];
3367 if (btrfs_node_blockptr(eb, path->slots[level]) != cur->bytenr) {
3369 "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
3370 cur->bytenr, level - 1, root->root_key.objectid,
3371 tree_key->objectid, tree_key->type, tree_key->offset);
3372 btrfs_put_root(root);
3378 /* Add all nodes and edges in the path */
3379 for (; level < BTRFS_MAX_LEVEL; level++) {
3380 if (!path->nodes[level]) {
3381 ASSERT(btrfs_root_bytenr(&root->root_item) ==
3383 /* Same as previous should_ignore_reloc_root() call */
3384 if (btrfs_should_ignore_reloc_root(root) &&
3386 btrfs_put_root(root);
3387 list_add(&lower->list, &cache->useless_node);
3394 edge = btrfs_backref_alloc_edge(cache);
3396 btrfs_put_root(root);
3401 eb = path->nodes[level];
3402 rb_node = rb_simple_search(&cache->rb_root, eb->start);
3404 upper = btrfs_backref_alloc_node(cache, eb->start,
3407 btrfs_put_root(root);
3408 btrfs_backref_free_edge(cache, edge);
3412 upper->owner = btrfs_header_owner(eb);
3413 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
3417 * If we know the block isn't shared we can avoid
3418 * checking its backrefs.
3420 if (btrfs_block_can_be_shared(trans, root, eb))
3426 * Add the block to pending list if we need to check its
3427 * backrefs, we only do this once while walking up a
3428 * tree as we will catch anything else later on.
3430 if (!upper->checked && need_check) {
3432 list_add_tail(&edge->list[UPPER],
3433 &cache->pending_edge);
3437 INIT_LIST_HEAD(&edge->list[UPPER]);
3440 upper = rb_entry(rb_node, struct btrfs_backref_node,
3442 ASSERT(upper->checked);
3443 INIT_LIST_HEAD(&edge->list[UPPER]);
3445 upper->owner = btrfs_header_owner(eb);
3447 btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER);
3450 btrfs_put_root(root);
3457 btrfs_release_path(path);
3462 * Add backref node @cur into @cache.
3464 * NOTE: Even if the function returned 0, @cur is not yet cached as its upper
3465 * links aren't yet bi-directional. Needs to finish such links.
3466 * Use btrfs_backref_finish_upper_links() to finish such linkage.
3468 * @trans: Transaction handle.
3469 * @path: Released path for indirect tree backref lookup
3470 * @iter: Released backref iter for extent tree search
3471 * @node_key: The first key of the tree block
3473 int btrfs_backref_add_tree_node(struct btrfs_trans_handle *trans,
3474 struct btrfs_backref_cache *cache,
3475 struct btrfs_path *path,
3476 struct btrfs_backref_iter *iter,
3477 struct btrfs_key *node_key,
3478 struct btrfs_backref_node *cur)
3480 struct btrfs_backref_edge *edge;
3481 struct btrfs_backref_node *exist;
3484 ret = btrfs_backref_iter_start(iter, cur->bytenr);
3488 * We skip the first btrfs_tree_block_info, as we don't use the key
3489 * stored in it, but fetch it from the tree block
3491 if (btrfs_backref_has_tree_block_info(iter)) {
3492 ret = btrfs_backref_iter_next(iter);
3495 /* No extra backref? This means the tree block is corrupted */
3501 WARN_ON(cur->checked);
3502 if (!list_empty(&cur->upper)) {
3504 * The backref was added previously when processing backref of
3505 * type BTRFS_TREE_BLOCK_REF_KEY
3507 ASSERT(list_is_singular(&cur->upper));
3508 edge = list_entry(cur->upper.next, struct btrfs_backref_edge,
3510 ASSERT(list_empty(&edge->list[UPPER]));
3511 exist = edge->node[UPPER];
3513 * Add the upper level block to pending list if we need check
3516 if (!exist->checked)
3517 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
3522 for (; ret == 0; ret = btrfs_backref_iter_next(iter)) {
3523 struct extent_buffer *eb;
3524 struct btrfs_key key;
3528 eb = iter->path->nodes[0];
3530 key.objectid = iter->bytenr;
3531 if (btrfs_backref_iter_is_inline_ref(iter)) {
3532 struct btrfs_extent_inline_ref *iref;
3534 /* Update key for inline backref */
3535 iref = (struct btrfs_extent_inline_ref *)
3536 ((unsigned long)iter->cur_ptr);
3537 type = btrfs_get_extent_inline_ref_type(eb, iref,
3538 BTRFS_REF_TYPE_BLOCK);
3539 if (type == BTRFS_REF_TYPE_INVALID) {
3544 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3546 key.type = iter->cur_key.type;
3547 key.offset = iter->cur_key.offset;
3551 * Parent node found and matches current inline ref, no need to
3552 * rebuild this node for this inline ref
3555 ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
3556 exist->owner == key.offset) ||
3557 (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
3558 exist->bytenr == key.offset))) {
3563 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */
3564 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
3565 ret = handle_direct_tree_backref(cache, &key, cur);
3568 } else if (key.type == BTRFS_TREE_BLOCK_REF_KEY) {
3570 * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref
3571 * offset means the root objectid. We need to search
3572 * the tree to get its parent bytenr.
3574 ret = handle_indirect_tree_backref(trans, cache, path,
3575 &key, node_key, cur);
3580 * Unrecognized tree backref items (if it can pass tree-checker)
3588 btrfs_backref_iter_release(iter);
3593 * Finish the upwards linkage created by btrfs_backref_add_tree_node()
3595 int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
3596 struct btrfs_backref_node *start)
3598 struct list_head *useless_node = &cache->useless_node;
3599 struct btrfs_backref_edge *edge;
3600 struct rb_node *rb_node;
3601 LIST_HEAD(pending_edge);
3603 ASSERT(start->checked);
3605 /* Insert this node to cache if it's not COW-only */
3606 if (!start->cowonly) {
3607 rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
3610 btrfs_backref_panic(cache->fs_info, start->bytenr,
3612 list_add_tail(&start->lower, &cache->leaves);
3616 * Use breadth first search to iterate all related edges.
3618 * The starting points are all the edges of this node
3620 list_for_each_entry(edge, &start->upper, list[LOWER])
3621 list_add_tail(&edge->list[UPPER], &pending_edge);
3623 while (!list_empty(&pending_edge)) {
3624 struct btrfs_backref_node *upper;
3625 struct btrfs_backref_node *lower;
3627 edge = list_first_entry(&pending_edge,
3628 struct btrfs_backref_edge, list[UPPER]);
3629 list_del_init(&edge->list[UPPER]);
3630 upper = edge->node[UPPER];
3631 lower = edge->node[LOWER];
3633 /* Parent is detached, no need to keep any edges */
3634 if (upper->detached) {
3635 list_del(&edge->list[LOWER]);
3636 btrfs_backref_free_edge(cache, edge);
3638 /* Lower node is orphan, queue for cleanup */
3639 if (list_empty(&lower->upper))
3640 list_add(&lower->list, useless_node);
3645 * All new nodes added in current build_backref_tree() haven't
3646 * been linked to the cache rb tree.
3647 * So if we have upper->rb_node populated, this means a cache
3648 * hit. We only need to link the edge, as @upper and all its
3649 * parents have already been linked.
3651 if (!RB_EMPTY_NODE(&upper->rb_node)) {
3652 if (upper->lowest) {
3653 list_del_init(&upper->lower);
3657 list_add_tail(&edge->list[UPPER], &upper->lower);
3661 /* Sanity check, we shouldn't have any unchecked nodes */
3662 if (!upper->checked) {
3667 /* Sanity check, COW-only node has non-COW-only parent */
3668 if (start->cowonly != upper->cowonly) {
3673 /* Only cache non-COW-only (subvolume trees) tree blocks */
3674 if (!upper->cowonly) {
3675 rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
3678 btrfs_backref_panic(cache->fs_info,
3679 upper->bytenr, -EEXIST);
3684 list_add_tail(&edge->list[UPPER], &upper->lower);
3687 * Also queue all the parent edges of this uncached node
3688 * to finish the upper linkage
3690 list_for_each_entry(edge, &upper->upper, list[LOWER])
3691 list_add_tail(&edge->list[UPPER], &pending_edge);
3696 void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
3697 struct btrfs_backref_node *node)
3699 struct btrfs_backref_node *lower;
3700 struct btrfs_backref_node *upper;
3701 struct btrfs_backref_edge *edge;
3703 while (!list_empty(&cache->useless_node)) {
3704 lower = list_first_entry(&cache->useless_node,
3705 struct btrfs_backref_node, list);
3706 list_del_init(&lower->list);
3708 while (!list_empty(&cache->pending_edge)) {
3709 edge = list_first_entry(&cache->pending_edge,
3710 struct btrfs_backref_edge, list[UPPER]);
3711 list_del(&edge->list[UPPER]);
3712 list_del(&edge->list[LOWER]);
3713 lower = edge->node[LOWER];
3714 upper = edge->node[UPPER];
3715 btrfs_backref_free_edge(cache, edge);
3718 * Lower is no longer linked to any upper backref nodes and
3719 * isn't in the cache, we can free it ourselves.
3721 if (list_empty(&lower->upper) &&
3722 RB_EMPTY_NODE(&lower->rb_node))
3723 list_add(&lower->list, &cache->useless_node);
3725 if (!RB_EMPTY_NODE(&upper->rb_node))
3728 /* Add this guy's upper edges to the list to process */
3729 list_for_each_entry(edge, &upper->upper, list[LOWER])
3730 list_add_tail(&edge->list[UPPER],
3731 &cache->pending_edge);
3732 if (list_empty(&upper->upper))
3733 list_add(&upper->list, &cache->useless_node);
3736 while (!list_empty(&cache->useless_node)) {
3737 lower = list_first_entry(&cache->useless_node,
3738 struct btrfs_backref_node, list);
3739 list_del_init(&lower->list);
3742 btrfs_backref_drop_node(cache, lower);
3745 btrfs_backref_cleanup_node(cache, node);
3746 ASSERT(list_empty(&cache->useless_node) &&
3747 list_empty(&cache->pending_edge));