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 /* Just an arbitrary number so we can be sure this happened */
20 #define BACKREF_FOUND_SHARED 6
22 struct extent_inode_elem {
25 struct extent_inode_elem *next;
28 static int check_extent_in_eb(const struct btrfs_key *key,
29 const struct extent_buffer *eb,
30 const struct btrfs_file_extent_item *fi,
32 struct extent_inode_elem **eie,
36 struct extent_inode_elem *e;
39 !btrfs_file_extent_compression(eb, fi) &&
40 !btrfs_file_extent_encryption(eb, fi) &&
41 !btrfs_file_extent_other_encoding(eb, fi)) {
45 data_offset = btrfs_file_extent_offset(eb, fi);
46 data_len = btrfs_file_extent_num_bytes(eb, fi);
48 if (extent_item_pos < data_offset ||
49 extent_item_pos >= data_offset + data_len)
51 offset = extent_item_pos - data_offset;
54 e = kmalloc(sizeof(*e), GFP_NOFS);
59 e->inum = key->objectid;
60 e->offset = key->offset + offset;
66 static void free_inode_elem_list(struct extent_inode_elem *eie)
68 struct extent_inode_elem *eie_next;
70 for (; eie; eie = eie_next) {
76 static int find_extent_in_eb(const struct extent_buffer *eb,
77 u64 wanted_disk_byte, u64 extent_item_pos,
78 struct extent_inode_elem **eie,
83 struct btrfs_file_extent_item *fi;
90 * from the shared data ref, we only have the leaf but we need
91 * the key. thus, we must look into all items and see that we
92 * find one (some) with a reference to our extent item.
94 nritems = btrfs_header_nritems(eb);
95 for (slot = 0; slot < nritems; ++slot) {
96 btrfs_item_key_to_cpu(eb, &key, slot);
97 if (key.type != BTRFS_EXTENT_DATA_KEY)
99 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
100 extent_type = btrfs_file_extent_type(eb, fi);
101 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
103 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
104 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
105 if (disk_byte != wanted_disk_byte)
108 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie, ignore_offset);
117 struct rb_root_cached root;
121 #define PREFTREE_INIT { .root = RB_ROOT_CACHED, .count = 0 }
124 struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */
125 struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */
126 struct preftree indirect_missing_keys;
130 * Checks for a shared extent during backref search.
132 * The share_count tracks prelim_refs (direct and indirect) having a
134 * - incremented when a ref->count transitions to >0
135 * - decremented when a ref->count transitions to <1
143 static inline int extent_is_shared(struct share_check *sc)
145 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
148 static struct kmem_cache *btrfs_prelim_ref_cache;
150 int __init btrfs_prelim_ref_init(void)
152 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
153 sizeof(struct prelim_ref),
157 if (!btrfs_prelim_ref_cache)
162 void __cold btrfs_prelim_ref_exit(void)
164 kmem_cache_destroy(btrfs_prelim_ref_cache);
167 static void free_pref(struct prelim_ref *ref)
169 kmem_cache_free(btrfs_prelim_ref_cache, ref);
173 * Return 0 when both refs are for the same block (and can be merged).
174 * A -1 return indicates ref1 is a 'lower' block than ref2, while 1
175 * indicates a 'higher' block.
177 static int prelim_ref_compare(struct prelim_ref *ref1,
178 struct prelim_ref *ref2)
180 if (ref1->level < ref2->level)
182 if (ref1->level > ref2->level)
184 if (ref1->root_id < ref2->root_id)
186 if (ref1->root_id > ref2->root_id)
188 if (ref1->key_for_search.type < ref2->key_for_search.type)
190 if (ref1->key_for_search.type > ref2->key_for_search.type)
192 if (ref1->key_for_search.objectid < ref2->key_for_search.objectid)
194 if (ref1->key_for_search.objectid > ref2->key_for_search.objectid)
196 if (ref1->key_for_search.offset < ref2->key_for_search.offset)
198 if (ref1->key_for_search.offset > ref2->key_for_search.offset)
200 if (ref1->parent < ref2->parent)
202 if (ref1->parent > ref2->parent)
208 static void update_share_count(struct share_check *sc, int oldcount,
211 if ((!sc) || (oldcount == 0 && newcount < 1))
214 if (oldcount > 0 && newcount < 1)
216 else if (oldcount < 1 && newcount > 0)
221 * Add @newref to the @root rbtree, merging identical refs.
223 * Callers should assume that newref has been freed after calling.
225 static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
226 struct preftree *preftree,
227 struct prelim_ref *newref,
228 struct share_check *sc)
230 struct rb_root_cached *root;
232 struct rb_node *parent = NULL;
233 struct prelim_ref *ref;
235 bool leftmost = true;
237 root = &preftree->root;
238 p = &root->rb_root.rb_node;
242 ref = rb_entry(parent, struct prelim_ref, rbnode);
243 result = prelim_ref_compare(ref, newref);
246 } else if (result > 0) {
250 /* Identical refs, merge them and free @newref */
251 struct extent_inode_elem *eie = ref->inode_list;
253 while (eie && eie->next)
257 ref->inode_list = newref->inode_list;
259 eie->next = newref->inode_list;
260 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
263 * A delayed ref can have newref->count < 0.
264 * The ref->count is updated to follow any
265 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
267 update_share_count(sc, ref->count,
268 ref->count + newref->count);
269 ref->count += newref->count;
275 update_share_count(sc, 0, newref->count);
277 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
278 rb_link_node(&newref->rbnode, parent, p);
279 rb_insert_color_cached(&newref->rbnode, root, leftmost);
283 * Release the entire tree. We don't care about internal consistency so
284 * just free everything and then reset the tree root.
286 static void prelim_release(struct preftree *preftree)
288 struct prelim_ref *ref, *next_ref;
290 rbtree_postorder_for_each_entry_safe(ref, next_ref,
291 &preftree->root.rb_root, rbnode)
294 preftree->root = RB_ROOT_CACHED;
299 * the rules for all callers of this function are:
300 * - obtaining the parent is the goal
301 * - if you add a key, you must know that it is a correct key
302 * - if you cannot add the parent or a correct key, then we will look into the
303 * block later to set a correct key
307 * backref type | shared | indirect | shared | indirect
308 * information | tree | tree | data | data
309 * --------------------+--------+----------+--------+----------
310 * parent logical | y | - | - | -
311 * key to resolve | - | y | y | y
312 * tree block logical | - | - | - | -
313 * root for resolving | y | y | y | y
315 * - column 1: we've the parent -> done
316 * - column 2, 3, 4: we use the key to find the parent
318 * on disk refs (inline or keyed)
319 * ==============================
320 * backref type | shared | indirect | shared | indirect
321 * information | tree | tree | data | data
322 * --------------------+--------+----------+--------+----------
323 * parent logical | y | - | y | -
324 * key to resolve | - | - | - | y
325 * tree block logical | y | y | y | y
326 * root for resolving | - | y | y | y
328 * - column 1, 3: we've the parent -> done
329 * - column 2: we take the first key from the block to find the parent
330 * (see add_missing_keys)
331 * - column 4: we use the key to find the parent
333 * additional information that's available but not required to find the parent
334 * block might help in merging entries to gain some speed.
336 static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
337 struct preftree *preftree, u64 root_id,
338 const struct btrfs_key *key, int level, u64 parent,
339 u64 wanted_disk_byte, int count,
340 struct share_check *sc, gfp_t gfp_mask)
342 struct prelim_ref *ref;
344 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
347 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
351 ref->root_id = root_id;
353 ref->key_for_search = *key;
355 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
357 ref->inode_list = NULL;
360 ref->parent = parent;
361 ref->wanted_disk_byte = wanted_disk_byte;
362 prelim_ref_insert(fs_info, preftree, ref, sc);
363 return extent_is_shared(sc);
366 /* direct refs use root == 0, key == NULL */
367 static int add_direct_ref(const struct btrfs_fs_info *fs_info,
368 struct preftrees *preftrees, int level, u64 parent,
369 u64 wanted_disk_byte, int count,
370 struct share_check *sc, gfp_t gfp_mask)
372 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
373 parent, wanted_disk_byte, count, sc, gfp_mask);
376 /* indirect refs use parent == 0 */
377 static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
378 struct preftrees *preftrees, u64 root_id,
379 const struct btrfs_key *key, int level,
380 u64 wanted_disk_byte, int count,
381 struct share_check *sc, gfp_t gfp_mask)
383 struct preftree *tree = &preftrees->indirect;
386 tree = &preftrees->indirect_missing_keys;
387 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
388 wanted_disk_byte, count, sc, gfp_mask);
391 static int is_shared_data_backref(struct preftrees *preftrees, u64 bytenr)
393 struct rb_node **p = &preftrees->direct.root.rb_root.rb_node;
394 struct rb_node *parent = NULL;
395 struct prelim_ref *ref = NULL;
396 struct prelim_ref target = {};
399 target.parent = bytenr;
403 ref = rb_entry(parent, struct prelim_ref, rbnode);
404 result = prelim_ref_compare(ref, &target);
416 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
417 struct ulist *parents,
418 struct preftrees *preftrees, struct prelim_ref *ref,
419 int level, u64 time_seq, const u64 *extent_item_pos,
424 struct extent_buffer *eb;
425 struct btrfs_key key;
426 struct btrfs_key *key_for_search = &ref->key_for_search;
427 struct btrfs_file_extent_item *fi;
428 struct extent_inode_elem *eie = NULL, *old = NULL;
430 u64 wanted_disk_byte = ref->wanted_disk_byte;
435 eb = path->nodes[level];
436 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
443 * 1. We normally enter this function with the path already pointing to
444 * the first item to check. But sometimes, we may enter it with
446 * 2. We are searching for normal backref but bytenr of this leaf
447 * matches shared data backref
448 * 3. The leaf owner is not equal to the root we are searching
450 * For these cases, go to the next leaf before we continue.
453 if (path->slots[0] >= btrfs_header_nritems(eb) ||
454 is_shared_data_backref(preftrees, eb->start) ||
455 ref->root_id != btrfs_header_owner(eb)) {
456 if (time_seq == BTRFS_SEQ_LAST)
457 ret = btrfs_next_leaf(root, path);
459 ret = btrfs_next_old_leaf(root, path, time_seq);
462 while (!ret && count < ref->count) {
464 slot = path->slots[0];
466 btrfs_item_key_to_cpu(eb, &key, slot);
468 if (key.objectid != key_for_search->objectid ||
469 key.type != BTRFS_EXTENT_DATA_KEY)
473 * We are searching for normal backref but bytenr of this leaf
474 * matches shared data backref, OR
475 * the leaf owner is not equal to the root we are searching for
478 (is_shared_data_backref(preftrees, eb->start) ||
479 ref->root_id != btrfs_header_owner(eb))) {
480 if (time_seq == BTRFS_SEQ_LAST)
481 ret = btrfs_next_leaf(root, path);
483 ret = btrfs_next_old_leaf(root, path, time_seq);
486 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
487 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
488 data_offset = btrfs_file_extent_offset(eb, fi);
490 if (disk_byte == wanted_disk_byte) {
493 if (ref->key_for_search.offset == key.offset - data_offset)
497 if (extent_item_pos) {
498 ret = check_extent_in_eb(&key, eb, fi,
500 &eie, ignore_offset);
506 ret = ulist_add_merge_ptr(parents, eb->start,
507 eie, (void **)&old, GFP_NOFS);
510 if (!ret && extent_item_pos) {
518 if (time_seq == BTRFS_SEQ_LAST)
519 ret = btrfs_next_item(root, path);
521 ret = btrfs_next_old_item(root, path, time_seq);
527 free_inode_elem_list(eie);
532 * resolve an indirect backref in the form (root_id, key, level)
533 * to a logical address
535 static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
536 struct btrfs_path *path, u64 time_seq,
537 struct preftrees *preftrees,
538 struct prelim_ref *ref, struct ulist *parents,
539 const u64 *extent_item_pos, bool ignore_offset)
541 struct btrfs_root *root;
542 struct extent_buffer *eb;
545 int level = ref->level;
546 struct btrfs_key search_key = ref->key_for_search;
549 * If we're search_commit_root we could possibly be holding locks on
550 * other tree nodes. This happens when qgroups does backref walks when
551 * adding new delayed refs. To deal with this we need to look in cache
552 * for the root, and if we don't find it then we need to search the
553 * tree_root's commit root, thus the btrfs_get_fs_root_commit_root usage
556 if (path->search_commit_root)
557 root = btrfs_get_fs_root_commit_root(fs_info, path, ref->root_id);
559 root = btrfs_get_fs_root(fs_info, ref->root_id, false);
565 if (!path->search_commit_root &&
566 test_bit(BTRFS_ROOT_DELETING, &root->state)) {
571 if (btrfs_is_testing(fs_info)) {
576 if (path->search_commit_root)
577 root_level = btrfs_header_level(root->commit_root);
578 else if (time_seq == BTRFS_SEQ_LAST)
579 root_level = btrfs_header_level(root->node);
581 root_level = btrfs_old_root_level(root, time_seq);
583 if (root_level + 1 == level)
587 * We can often find data backrefs with an offset that is too large
588 * (>= LLONG_MAX, maximum allowed file offset) due to underflows when
589 * subtracting a file's offset with the data offset of its
590 * corresponding extent data item. This can happen for example in the
593 * So if we detect such case we set the search key's offset to zero to
594 * make sure we will find the matching file extent item at
595 * add_all_parents(), otherwise we will miss it because the offset
596 * taken form the backref is much larger then the offset of the file
597 * extent item. This can make us scan a very large number of file
598 * extent items, but at least it will not make us miss any.
600 * This is an ugly workaround for a behaviour that should have never
601 * existed, but it does and a fix for the clone ioctl would touch a lot
602 * of places, cause backwards incompatibility and would not fix the
603 * problem for extents cloned with older kernels.
605 if (search_key.type == BTRFS_EXTENT_DATA_KEY &&
606 search_key.offset >= LLONG_MAX)
607 search_key.offset = 0;
608 path->lowest_level = level;
609 if (time_seq == BTRFS_SEQ_LAST)
610 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
612 ret = btrfs_search_old_slot(root, &search_key, path, time_seq);
615 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
616 ref->root_id, level, ref->count, ret,
617 ref->key_for_search.objectid, ref->key_for_search.type,
618 ref->key_for_search.offset);
622 eb = path->nodes[level];
624 if (WARN_ON(!level)) {
629 eb = path->nodes[level];
632 ret = add_all_parents(root, path, parents, preftrees, ref, level,
633 time_seq, extent_item_pos, ignore_offset);
635 btrfs_put_root(root);
637 path->lowest_level = 0;
638 btrfs_release_path(path);
642 static struct extent_inode_elem *
643 unode_aux_to_inode_list(struct ulist_node *node)
647 return (struct extent_inode_elem *)(uintptr_t)node->aux;
651 * We maintain three separate rbtrees: one for direct refs, one for
652 * indirect refs which have a key, and one for indirect refs which do not
653 * have a key. Each tree does merge on insertion.
655 * Once all of the references are located, we iterate over the tree of
656 * indirect refs with missing keys. An appropriate key is located and
657 * the ref is moved onto the tree for indirect refs. After all missing
658 * keys are thus located, we iterate over the indirect ref tree, resolve
659 * each reference, and then insert the resolved reference onto the
660 * direct tree (merging there too).
662 * New backrefs (i.e., for parent nodes) are added to the appropriate
663 * rbtree as they are encountered. The new backrefs are subsequently
666 static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
667 struct btrfs_path *path, u64 time_seq,
668 struct preftrees *preftrees,
669 const u64 *extent_item_pos,
670 struct share_check *sc, bool ignore_offset)
674 struct ulist *parents;
675 struct ulist_node *node;
676 struct ulist_iterator uiter;
677 struct rb_node *rnode;
679 parents = ulist_alloc(GFP_NOFS);
684 * We could trade memory usage for performance here by iterating
685 * the tree, allocating new refs for each insertion, and then
686 * freeing the entire indirect tree when we're done. In some test
687 * cases, the tree can grow quite large (~200k objects).
689 while ((rnode = rb_first_cached(&preftrees->indirect.root))) {
690 struct prelim_ref *ref;
692 ref = rb_entry(rnode, struct prelim_ref, rbnode);
693 if (WARN(ref->parent,
694 "BUG: direct ref found in indirect tree")) {
699 rb_erase_cached(&ref->rbnode, &preftrees->indirect.root);
700 preftrees->indirect.count--;
702 if (ref->count == 0) {
707 if (sc && sc->root_objectid &&
708 ref->root_id != sc->root_objectid) {
710 ret = BACKREF_FOUND_SHARED;
713 err = resolve_indirect_ref(fs_info, path, time_seq, preftrees,
714 ref, parents, extent_item_pos,
717 * we can only tolerate ENOENT,otherwise,we should catch error
718 * and return directly.
720 if (err == -ENOENT) {
721 prelim_ref_insert(fs_info, &preftrees->direct, ref,
730 /* we put the first parent into the ref at hand */
731 ULIST_ITER_INIT(&uiter);
732 node = ulist_next(parents, &uiter);
733 ref->parent = node ? node->val : 0;
734 ref->inode_list = unode_aux_to_inode_list(node);
736 /* Add a prelim_ref(s) for any other parent(s). */
737 while ((node = ulist_next(parents, &uiter))) {
738 struct prelim_ref *new_ref;
740 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
747 memcpy(new_ref, ref, sizeof(*ref));
748 new_ref->parent = node->val;
749 new_ref->inode_list = unode_aux_to_inode_list(node);
750 prelim_ref_insert(fs_info, &preftrees->direct,
755 * Now it's a direct ref, put it in the direct tree. We must
756 * do this last because the ref could be merged/freed here.
758 prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL);
760 ulist_reinit(parents);
769 * read tree blocks and add keys where required.
771 static int add_missing_keys(struct btrfs_fs_info *fs_info,
772 struct preftrees *preftrees, bool lock)
774 struct prelim_ref *ref;
775 struct extent_buffer *eb;
776 struct preftree *tree = &preftrees->indirect_missing_keys;
777 struct rb_node *node;
779 while ((node = rb_first_cached(&tree->root))) {
780 ref = rb_entry(node, struct prelim_ref, rbnode);
781 rb_erase_cached(node, &tree->root);
783 BUG_ON(ref->parent); /* should not be a direct ref */
784 BUG_ON(ref->key_for_search.type);
785 BUG_ON(!ref->wanted_disk_byte);
787 eb = read_tree_block(fs_info, ref->wanted_disk_byte,
788 ref->root_id, 0, ref->level - 1, NULL);
793 if (!extent_buffer_uptodate(eb)) {
795 free_extent_buffer(eb);
800 btrfs_tree_read_lock(eb);
801 if (btrfs_header_level(eb) == 0)
802 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
804 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
806 btrfs_tree_read_unlock(eb);
807 free_extent_buffer(eb);
808 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
815 * add all currently queued delayed refs from this head whose seq nr is
816 * smaller or equal that seq to the list
818 static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
819 struct btrfs_delayed_ref_head *head, u64 seq,
820 struct preftrees *preftrees, struct share_check *sc)
822 struct btrfs_delayed_ref_node *node;
823 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
824 struct btrfs_key key;
825 struct btrfs_key tmp_op_key;
830 if (extent_op && extent_op->update_key)
831 btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
833 spin_lock(&head->lock);
834 for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
835 node = rb_entry(n, struct btrfs_delayed_ref_node,
840 switch (node->action) {
841 case BTRFS_ADD_DELAYED_EXTENT:
842 case BTRFS_UPDATE_DELAYED_HEAD:
845 case BTRFS_ADD_DELAYED_REF:
846 count = node->ref_mod;
848 case BTRFS_DROP_DELAYED_REF:
849 count = node->ref_mod * -1;
854 switch (node->type) {
855 case BTRFS_TREE_BLOCK_REF_KEY: {
856 /* NORMAL INDIRECT METADATA backref */
857 struct btrfs_delayed_tree_ref *ref;
859 ref = btrfs_delayed_node_to_tree_ref(node);
860 ret = add_indirect_ref(fs_info, preftrees, ref->root,
861 &tmp_op_key, ref->level + 1,
862 node->bytenr, count, sc,
866 case BTRFS_SHARED_BLOCK_REF_KEY: {
867 /* SHARED DIRECT METADATA backref */
868 struct btrfs_delayed_tree_ref *ref;
870 ref = btrfs_delayed_node_to_tree_ref(node);
872 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
873 ref->parent, node->bytenr, count,
877 case BTRFS_EXTENT_DATA_REF_KEY: {
878 /* NORMAL INDIRECT DATA backref */
879 struct btrfs_delayed_data_ref *ref;
880 ref = btrfs_delayed_node_to_data_ref(node);
882 key.objectid = ref->objectid;
883 key.type = BTRFS_EXTENT_DATA_KEY;
884 key.offset = ref->offset;
887 * Found a inum that doesn't match our known inum, we
890 if (sc && sc->inum && ref->objectid != sc->inum) {
891 ret = BACKREF_FOUND_SHARED;
895 ret = add_indirect_ref(fs_info, preftrees, ref->root,
896 &key, 0, node->bytenr, count, sc,
900 case BTRFS_SHARED_DATA_REF_KEY: {
901 /* SHARED DIRECT FULL backref */
902 struct btrfs_delayed_data_ref *ref;
904 ref = btrfs_delayed_node_to_data_ref(node);
906 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
907 node->bytenr, count, sc,
915 * We must ignore BACKREF_FOUND_SHARED until all delayed
916 * refs have been checked.
918 if (ret && (ret != BACKREF_FOUND_SHARED))
922 ret = extent_is_shared(sc);
924 spin_unlock(&head->lock);
929 * add all inline backrefs for bytenr to the list
931 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
933 static int add_inline_refs(const struct btrfs_fs_info *fs_info,
934 struct btrfs_path *path, u64 bytenr,
935 int *info_level, struct preftrees *preftrees,
936 struct share_check *sc)
940 struct extent_buffer *leaf;
941 struct btrfs_key key;
942 struct btrfs_key found_key;
945 struct btrfs_extent_item *ei;
950 * enumerate all inline refs
952 leaf = path->nodes[0];
953 slot = path->slots[0];
955 item_size = btrfs_item_size(leaf, slot);
956 BUG_ON(item_size < sizeof(*ei));
958 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
959 flags = btrfs_extent_flags(leaf, ei);
960 btrfs_item_key_to_cpu(leaf, &found_key, slot);
962 ptr = (unsigned long)(ei + 1);
963 end = (unsigned long)ei + item_size;
965 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
966 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
967 struct btrfs_tree_block_info *info;
969 info = (struct btrfs_tree_block_info *)ptr;
970 *info_level = btrfs_tree_block_level(leaf, info);
971 ptr += sizeof(struct btrfs_tree_block_info);
973 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
974 *info_level = found_key.offset;
976 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
980 struct btrfs_extent_inline_ref *iref;
984 iref = (struct btrfs_extent_inline_ref *)ptr;
985 type = btrfs_get_extent_inline_ref_type(leaf, iref,
987 if (type == BTRFS_REF_TYPE_INVALID)
990 offset = btrfs_extent_inline_ref_offset(leaf, iref);
993 case BTRFS_SHARED_BLOCK_REF_KEY:
994 ret = add_direct_ref(fs_info, preftrees,
995 *info_level + 1, offset,
996 bytenr, 1, NULL, GFP_NOFS);
998 case BTRFS_SHARED_DATA_REF_KEY: {
999 struct btrfs_shared_data_ref *sdref;
1002 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
1003 count = btrfs_shared_data_ref_count(leaf, sdref);
1005 ret = add_direct_ref(fs_info, preftrees, 0, offset,
1006 bytenr, count, sc, GFP_NOFS);
1009 case BTRFS_TREE_BLOCK_REF_KEY:
1010 ret = add_indirect_ref(fs_info, preftrees, offset,
1011 NULL, *info_level + 1,
1012 bytenr, 1, NULL, GFP_NOFS);
1014 case BTRFS_EXTENT_DATA_REF_KEY: {
1015 struct btrfs_extent_data_ref *dref;
1019 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1020 count = btrfs_extent_data_ref_count(leaf, dref);
1021 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1023 key.type = BTRFS_EXTENT_DATA_KEY;
1024 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1026 if (sc && sc->inum && key.objectid != sc->inum) {
1027 ret = BACKREF_FOUND_SHARED;
1031 root = btrfs_extent_data_ref_root(leaf, dref);
1033 ret = add_indirect_ref(fs_info, preftrees, root,
1034 &key, 0, bytenr, count,
1043 ptr += btrfs_extent_inline_ref_size(type);
1050 * add all non-inline backrefs for bytenr to the list
1052 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
1054 static int add_keyed_refs(struct btrfs_root *extent_root,
1055 struct btrfs_path *path, u64 bytenr,
1056 int info_level, struct preftrees *preftrees,
1057 struct share_check *sc)
1059 struct btrfs_fs_info *fs_info = extent_root->fs_info;
1062 struct extent_buffer *leaf;
1063 struct btrfs_key key;
1066 ret = btrfs_next_item(extent_root, path);
1074 slot = path->slots[0];
1075 leaf = path->nodes[0];
1076 btrfs_item_key_to_cpu(leaf, &key, slot);
1078 if (key.objectid != bytenr)
1080 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1082 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1086 case BTRFS_SHARED_BLOCK_REF_KEY:
1087 /* SHARED DIRECT METADATA backref */
1088 ret = add_direct_ref(fs_info, preftrees,
1089 info_level + 1, key.offset,
1090 bytenr, 1, NULL, GFP_NOFS);
1092 case BTRFS_SHARED_DATA_REF_KEY: {
1093 /* SHARED DIRECT FULL backref */
1094 struct btrfs_shared_data_ref *sdref;
1097 sdref = btrfs_item_ptr(leaf, slot,
1098 struct btrfs_shared_data_ref);
1099 count = btrfs_shared_data_ref_count(leaf, sdref);
1100 ret = add_direct_ref(fs_info, preftrees, 0,
1101 key.offset, bytenr, count,
1105 case BTRFS_TREE_BLOCK_REF_KEY:
1106 /* NORMAL INDIRECT METADATA backref */
1107 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1108 NULL, info_level + 1, bytenr,
1111 case BTRFS_EXTENT_DATA_REF_KEY: {
1112 /* NORMAL INDIRECT DATA backref */
1113 struct btrfs_extent_data_ref *dref;
1117 dref = btrfs_item_ptr(leaf, slot,
1118 struct btrfs_extent_data_ref);
1119 count = btrfs_extent_data_ref_count(leaf, dref);
1120 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1122 key.type = BTRFS_EXTENT_DATA_KEY;
1123 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1125 if (sc && sc->inum && key.objectid != sc->inum) {
1126 ret = BACKREF_FOUND_SHARED;
1130 root = btrfs_extent_data_ref_root(leaf, dref);
1131 ret = add_indirect_ref(fs_info, preftrees, root,
1132 &key, 0, bytenr, count,
1148 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1149 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1150 * indirect refs to their parent bytenr.
1151 * When roots are found, they're added to the roots list
1153 * If time_seq is set to BTRFS_SEQ_LAST, it will not search delayed_refs, and
1154 * behave much like trans == NULL case, the difference only lies in it will not
1156 * The special case is for qgroup to search roots in commit_transaction().
1158 * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a
1159 * shared extent is detected.
1161 * Otherwise this returns 0 for success and <0 for an error.
1163 * If ignore_offset is set to false, only extent refs whose offsets match
1164 * extent_item_pos are returned. If true, every extent ref is returned
1165 * and extent_item_pos is ignored.
1167 * FIXME some caching might speed things up
1169 static int find_parent_nodes(struct btrfs_trans_handle *trans,
1170 struct btrfs_fs_info *fs_info, u64 bytenr,
1171 u64 time_seq, struct ulist *refs,
1172 struct ulist *roots, const u64 *extent_item_pos,
1173 struct share_check *sc, bool ignore_offset)
1175 struct btrfs_root *root = btrfs_extent_root(fs_info, bytenr);
1176 struct btrfs_key key;
1177 struct btrfs_path *path;
1178 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1179 struct btrfs_delayed_ref_head *head;
1182 struct prelim_ref *ref;
1183 struct rb_node *node;
1184 struct extent_inode_elem *eie = NULL;
1185 struct preftrees preftrees = {
1186 .direct = PREFTREE_INIT,
1187 .indirect = PREFTREE_INIT,
1188 .indirect_missing_keys = PREFTREE_INIT
1191 key.objectid = bytenr;
1192 key.offset = (u64)-1;
1193 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1194 key.type = BTRFS_METADATA_ITEM_KEY;
1196 key.type = BTRFS_EXTENT_ITEM_KEY;
1198 path = btrfs_alloc_path();
1202 path->search_commit_root = 1;
1203 path->skip_locking = 1;
1206 if (time_seq == BTRFS_SEQ_LAST)
1207 path->skip_locking = 1;
1212 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1216 /* This shouldn't happen, indicates a bug or fs corruption. */
1222 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1223 time_seq != BTRFS_SEQ_LAST) {
1225 * We have a specific time_seq we care about and trans which
1226 * means we have the path lock, we need to grab the ref head and
1227 * lock it so we have a consistent view of the refs at the given
1230 delayed_refs = &trans->transaction->delayed_refs;
1231 spin_lock(&delayed_refs->lock);
1232 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
1234 if (!mutex_trylock(&head->mutex)) {
1235 refcount_inc(&head->refs);
1236 spin_unlock(&delayed_refs->lock);
1238 btrfs_release_path(path);
1241 * Mutex was contended, block until it's
1242 * released and try again
1244 mutex_lock(&head->mutex);
1245 mutex_unlock(&head->mutex);
1246 btrfs_put_delayed_ref_head(head);
1249 spin_unlock(&delayed_refs->lock);
1250 ret = add_delayed_refs(fs_info, head, time_seq,
1252 mutex_unlock(&head->mutex);
1256 spin_unlock(&delayed_refs->lock);
1260 if (path->slots[0]) {
1261 struct extent_buffer *leaf;
1265 leaf = path->nodes[0];
1266 slot = path->slots[0];
1267 btrfs_item_key_to_cpu(leaf, &key, slot);
1268 if (key.objectid == bytenr &&
1269 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1270 key.type == BTRFS_METADATA_ITEM_KEY)) {
1271 ret = add_inline_refs(fs_info, path, bytenr,
1272 &info_level, &preftrees, sc);
1275 ret = add_keyed_refs(root, path, bytenr, info_level,
1282 btrfs_release_path(path);
1284 ret = add_missing_keys(fs_info, &preftrees, path->skip_locking == 0);
1288 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root));
1290 ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees,
1291 extent_item_pos, sc, ignore_offset);
1295 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root));
1298 * This walks the tree of merged and resolved refs. Tree blocks are
1299 * read in as needed. Unique entries are added to the ulist, and
1300 * the list of found roots is updated.
1302 * We release the entire tree in one go before returning.
1304 node = rb_first_cached(&preftrees.direct.root);
1306 ref = rb_entry(node, struct prelim_ref, rbnode);
1307 node = rb_next(&ref->rbnode);
1309 * ref->count < 0 can happen here if there are delayed
1310 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1311 * prelim_ref_insert() relies on this when merging
1312 * identical refs to keep the overall count correct.
1313 * prelim_ref_insert() will merge only those refs
1314 * which compare identically. Any refs having
1315 * e.g. different offsets would not be merged,
1316 * and would retain their original ref->count < 0.
1318 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1319 if (sc && sc->root_objectid &&
1320 ref->root_id != sc->root_objectid) {
1321 ret = BACKREF_FOUND_SHARED;
1325 /* no parent == root of tree */
1326 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1330 if (ref->count && ref->parent) {
1331 if (extent_item_pos && !ref->inode_list &&
1333 struct extent_buffer *eb;
1335 eb = read_tree_block(fs_info, ref->parent, 0,
1336 0, ref->level, NULL);
1341 if (!extent_buffer_uptodate(eb)) {
1342 free_extent_buffer(eb);
1347 if (!path->skip_locking)
1348 btrfs_tree_read_lock(eb);
1349 ret = find_extent_in_eb(eb, bytenr,
1350 *extent_item_pos, &eie, ignore_offset);
1351 if (!path->skip_locking)
1352 btrfs_tree_read_unlock(eb);
1353 free_extent_buffer(eb);
1356 ref->inode_list = eie;
1358 ret = ulist_add_merge_ptr(refs, ref->parent,
1360 (void **)&eie, GFP_NOFS);
1363 if (!ret && extent_item_pos) {
1365 * We've recorded that parent, so we must extend
1366 * its inode list here.
1368 * However if there was corruption we may not
1369 * have found an eie, return an error in this
1379 eie->next = ref->inode_list;
1387 btrfs_free_path(path);
1389 prelim_release(&preftrees.direct);
1390 prelim_release(&preftrees.indirect);
1391 prelim_release(&preftrees.indirect_missing_keys);
1394 free_inode_elem_list(eie);
1398 static void free_leaf_list(struct ulist *blocks)
1400 struct ulist_node *node = NULL;
1401 struct extent_inode_elem *eie;
1402 struct ulist_iterator uiter;
1404 ULIST_ITER_INIT(&uiter);
1405 while ((node = ulist_next(blocks, &uiter))) {
1408 eie = unode_aux_to_inode_list(node);
1409 free_inode_elem_list(eie);
1417 * Finds all leafs with a reference to the specified combination of bytenr and
1418 * offset. key_list_head will point to a list of corresponding keys (caller must
1419 * free each list element). The leafs will be stored in the leafs ulist, which
1420 * must be freed with ulist_free.
1422 * returns 0 on success, <0 on error
1424 int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1425 struct btrfs_fs_info *fs_info, u64 bytenr,
1426 u64 time_seq, struct ulist **leafs,
1427 const u64 *extent_item_pos, bool ignore_offset)
1431 *leafs = ulist_alloc(GFP_NOFS);
1435 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1436 *leafs, NULL, extent_item_pos, NULL, ignore_offset);
1437 if (ret < 0 && ret != -ENOENT) {
1438 free_leaf_list(*leafs);
1446 * walk all backrefs for a given extent to find all roots that reference this
1447 * extent. Walking a backref means finding all extents that reference this
1448 * extent and in turn walk the backrefs of those, too. Naturally this is a
1449 * recursive process, but here it is implemented in an iterative fashion: We
1450 * find all referencing extents for the extent in question and put them on a
1451 * list. In turn, we find all referencing extents for those, further appending
1452 * to the list. The way we iterate the list allows adding more elements after
1453 * the current while iterating. The process stops when we reach the end of the
1454 * list. Found roots are added to the roots list.
1456 * returns 0 on success, < 0 on error.
1458 static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
1459 struct btrfs_fs_info *fs_info, u64 bytenr,
1460 u64 time_seq, struct ulist **roots,
1464 struct ulist_node *node = NULL;
1465 struct ulist_iterator uiter;
1468 tmp = ulist_alloc(GFP_NOFS);
1471 *roots = ulist_alloc(GFP_NOFS);
1477 ULIST_ITER_INIT(&uiter);
1479 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1480 tmp, *roots, NULL, NULL, ignore_offset);
1481 if (ret < 0 && ret != -ENOENT) {
1487 node = ulist_next(tmp, &uiter);
1498 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1499 struct btrfs_fs_info *fs_info, u64 bytenr,
1500 u64 time_seq, struct ulist **roots,
1501 bool skip_commit_root_sem)
1505 if (!trans && !skip_commit_root_sem)
1506 down_read(&fs_info->commit_root_sem);
1507 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr,
1508 time_seq, roots, false);
1509 if (!trans && !skip_commit_root_sem)
1510 up_read(&fs_info->commit_root_sem);
1515 * Check if an extent is shared or not
1517 * @root: root inode belongs to
1518 * @inum: inode number of the inode whose extent we are checking
1519 * @bytenr: logical bytenr of the extent we are checking
1520 * @roots: list of roots this extent is shared among
1521 * @tmp: temporary list used for iteration
1523 * btrfs_check_shared uses the backref walking code but will short
1524 * circuit as soon as it finds a root or inode that doesn't match the
1525 * one passed in. This provides a significant performance benefit for
1526 * callers (such as fiemap) which want to know whether the extent is
1527 * shared but do not need a ref count.
1529 * This attempts to attach to the running transaction in order to account for
1530 * delayed refs, but continues on even when no running transaction exists.
1532 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1534 int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr,
1535 struct ulist *roots, struct ulist *tmp)
1537 struct btrfs_fs_info *fs_info = root->fs_info;
1538 struct btrfs_trans_handle *trans;
1539 struct ulist_iterator uiter;
1540 struct ulist_node *node;
1541 struct btrfs_seq_list elem = BTRFS_SEQ_LIST_INIT(elem);
1543 struct share_check shared = {
1544 .root_objectid = root->root_key.objectid,
1552 trans = btrfs_join_transaction_nostart(root);
1553 if (IS_ERR(trans)) {
1554 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
1555 ret = PTR_ERR(trans);
1559 down_read(&fs_info->commit_root_sem);
1561 btrfs_get_tree_mod_seq(fs_info, &elem);
1564 ULIST_ITER_INIT(&uiter);
1566 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1567 roots, NULL, &shared, false);
1568 if (ret == BACKREF_FOUND_SHARED) {
1569 /* this is the only condition under which we return 1 */
1573 if (ret < 0 && ret != -ENOENT)
1576 node = ulist_next(tmp, &uiter);
1580 shared.share_count = 0;
1585 btrfs_put_tree_mod_seq(fs_info, &elem);
1586 btrfs_end_transaction(trans);
1588 up_read(&fs_info->commit_root_sem);
1591 ulist_release(roots);
1596 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1597 u64 start_off, struct btrfs_path *path,
1598 struct btrfs_inode_extref **ret_extref,
1602 struct btrfs_key key;
1603 struct btrfs_key found_key;
1604 struct btrfs_inode_extref *extref;
1605 const struct extent_buffer *leaf;
1608 key.objectid = inode_objectid;
1609 key.type = BTRFS_INODE_EXTREF_KEY;
1610 key.offset = start_off;
1612 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1617 leaf = path->nodes[0];
1618 slot = path->slots[0];
1619 if (slot >= btrfs_header_nritems(leaf)) {
1621 * If the item at offset is not found,
1622 * btrfs_search_slot will point us to the slot
1623 * where it should be inserted. In our case
1624 * that will be the slot directly before the
1625 * next INODE_REF_KEY_V2 item. In the case
1626 * that we're pointing to the last slot in a
1627 * leaf, we must move one leaf over.
1629 ret = btrfs_next_leaf(root, path);
1638 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1641 * Check that we're still looking at an extended ref key for
1642 * this particular objectid. If we have different
1643 * objectid or type then there are no more to be found
1644 * in the tree and we can exit.
1647 if (found_key.objectid != inode_objectid)
1649 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1653 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1654 extref = (struct btrfs_inode_extref *)ptr;
1655 *ret_extref = extref;
1657 *found_off = found_key.offset;
1665 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1666 * Elements of the path are separated by '/' and the path is guaranteed to be
1667 * 0-terminated. the path is only given within the current file system.
1668 * Therefore, it never starts with a '/'. the caller is responsible to provide
1669 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1670 * the start point of the resulting string is returned. this pointer is within
1672 * in case the path buffer would overflow, the pointer is decremented further
1673 * as if output was written to the buffer, though no more output is actually
1674 * generated. that way, the caller can determine how much space would be
1675 * required for the path to fit into the buffer. in that case, the returned
1676 * value will be smaller than dest. callers must check this!
1678 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1679 u32 name_len, unsigned long name_off,
1680 struct extent_buffer *eb_in, u64 parent,
1681 char *dest, u32 size)
1686 s64 bytes_left = ((s64)size) - 1;
1687 struct extent_buffer *eb = eb_in;
1688 struct btrfs_key found_key;
1689 struct btrfs_inode_ref *iref;
1691 if (bytes_left >= 0)
1692 dest[bytes_left] = '\0';
1695 bytes_left -= name_len;
1696 if (bytes_left >= 0)
1697 read_extent_buffer(eb, dest + bytes_left,
1698 name_off, name_len);
1700 if (!path->skip_locking)
1701 btrfs_tree_read_unlock(eb);
1702 free_extent_buffer(eb);
1704 ret = btrfs_find_item(fs_root, path, parent, 0,
1705 BTRFS_INODE_REF_KEY, &found_key);
1711 next_inum = found_key.offset;
1713 /* regular exit ahead */
1714 if (parent == next_inum)
1717 slot = path->slots[0];
1718 eb = path->nodes[0];
1719 /* make sure we can use eb after releasing the path */
1721 path->nodes[0] = NULL;
1724 btrfs_release_path(path);
1725 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1727 name_len = btrfs_inode_ref_name_len(eb, iref);
1728 name_off = (unsigned long)(iref + 1);
1732 if (bytes_left >= 0)
1733 dest[bytes_left] = '/';
1736 btrfs_release_path(path);
1739 return ERR_PTR(ret);
1741 return dest + bytes_left;
1745 * this makes the path point to (logical EXTENT_ITEM *)
1746 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1747 * tree blocks and <0 on error.
1749 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1750 struct btrfs_path *path, struct btrfs_key *found_key,
1753 struct btrfs_root *extent_root = btrfs_extent_root(fs_info, logical);
1758 const struct extent_buffer *eb;
1759 struct btrfs_extent_item *ei;
1760 struct btrfs_key key;
1762 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1763 key.type = BTRFS_METADATA_ITEM_KEY;
1765 key.type = BTRFS_EXTENT_ITEM_KEY;
1766 key.objectid = logical;
1767 key.offset = (u64)-1;
1769 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
1773 ret = btrfs_previous_extent_item(extent_root, path, 0);
1779 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1780 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1781 size = fs_info->nodesize;
1782 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1783 size = found_key->offset;
1785 if (found_key->objectid > logical ||
1786 found_key->objectid + size <= logical) {
1787 btrfs_debug(fs_info,
1788 "logical %llu is not within any extent", logical);
1792 eb = path->nodes[0];
1793 item_size = btrfs_item_size(eb, path->slots[0]);
1794 BUG_ON(item_size < sizeof(*ei));
1796 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1797 flags = btrfs_extent_flags(eb, ei);
1799 btrfs_debug(fs_info,
1800 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1801 logical, logical - found_key->objectid, found_key->objectid,
1802 found_key->offset, flags, item_size);
1804 WARN_ON(!flags_ret);
1806 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1807 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1808 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1809 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1819 * helper function to iterate extent inline refs. ptr must point to a 0 value
1820 * for the first call and may be modified. it is used to track state.
1821 * if more refs exist, 0 is returned and the next call to
1822 * get_extent_inline_ref must pass the modified ptr parameter to get the
1823 * next ref. after the last ref was processed, 1 is returned.
1824 * returns <0 on error
1826 static int get_extent_inline_ref(unsigned long *ptr,
1827 const struct extent_buffer *eb,
1828 const struct btrfs_key *key,
1829 const struct btrfs_extent_item *ei,
1831 struct btrfs_extent_inline_ref **out_eiref,
1836 struct btrfs_tree_block_info *info;
1840 flags = btrfs_extent_flags(eb, ei);
1841 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1842 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1843 /* a skinny metadata extent */
1845 (struct btrfs_extent_inline_ref *)(ei + 1);
1847 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1848 info = (struct btrfs_tree_block_info *)(ei + 1);
1850 (struct btrfs_extent_inline_ref *)(info + 1);
1853 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1855 *ptr = (unsigned long)*out_eiref;
1856 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1860 end = (unsigned long)ei + item_size;
1861 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1862 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
1863 BTRFS_REF_TYPE_ANY);
1864 if (*out_type == BTRFS_REF_TYPE_INVALID)
1867 *ptr += btrfs_extent_inline_ref_size(*out_type);
1868 WARN_ON(*ptr > end);
1870 return 1; /* last */
1876 * reads the tree block backref for an extent. tree level and root are returned
1877 * through out_level and out_root. ptr must point to a 0 value for the first
1878 * call and may be modified (see get_extent_inline_ref comment).
1879 * returns 0 if data was provided, 1 if there was no more data to provide or
1882 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1883 struct btrfs_key *key, struct btrfs_extent_item *ei,
1884 u32 item_size, u64 *out_root, u8 *out_level)
1888 struct btrfs_extent_inline_ref *eiref;
1890 if (*ptr == (unsigned long)-1)
1894 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
1899 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1900 type == BTRFS_SHARED_BLOCK_REF_KEY)
1907 /* we can treat both ref types equally here */
1908 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1910 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1911 struct btrfs_tree_block_info *info;
1913 info = (struct btrfs_tree_block_info *)(ei + 1);
1914 *out_level = btrfs_tree_block_level(eb, info);
1916 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1917 *out_level = (u8)key->offset;
1921 *ptr = (unsigned long)-1;
1926 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1927 struct extent_inode_elem *inode_list,
1928 u64 root, u64 extent_item_objectid,
1929 iterate_extent_inodes_t *iterate, void *ctx)
1931 struct extent_inode_elem *eie;
1934 for (eie = inode_list; eie; eie = eie->next) {
1935 btrfs_debug(fs_info,
1936 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1937 extent_item_objectid, eie->inum,
1939 ret = iterate(eie->inum, eie->offset, root, ctx);
1941 btrfs_debug(fs_info,
1942 "stopping iteration for %llu due to ret=%d",
1943 extent_item_objectid, ret);
1952 * calls iterate() for every inode that references the extent identified by
1953 * the given parameters.
1954 * when the iterator function returns a non-zero value, iteration stops.
1956 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1957 u64 extent_item_objectid, u64 extent_item_pos,
1958 int search_commit_root,
1959 iterate_extent_inodes_t *iterate, void *ctx,
1963 struct btrfs_trans_handle *trans = NULL;
1964 struct ulist *refs = NULL;
1965 struct ulist *roots = NULL;
1966 struct ulist_node *ref_node = NULL;
1967 struct ulist_node *root_node = NULL;
1968 struct btrfs_seq_list seq_elem = BTRFS_SEQ_LIST_INIT(seq_elem);
1969 struct ulist_iterator ref_uiter;
1970 struct ulist_iterator root_uiter;
1972 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
1973 extent_item_objectid);
1975 if (!search_commit_root) {
1976 trans = btrfs_attach_transaction(fs_info->tree_root);
1977 if (IS_ERR(trans)) {
1978 if (PTR_ERR(trans) != -ENOENT &&
1979 PTR_ERR(trans) != -EROFS)
1980 return PTR_ERR(trans);
1986 btrfs_get_tree_mod_seq(fs_info, &seq_elem);
1988 down_read(&fs_info->commit_root_sem);
1990 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1991 seq_elem.seq, &refs,
1992 &extent_item_pos, ignore_offset);
1996 ULIST_ITER_INIT(&ref_uiter);
1997 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1998 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val,
1999 seq_elem.seq, &roots,
2003 ULIST_ITER_INIT(&root_uiter);
2004 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
2005 btrfs_debug(fs_info,
2006 "root %llu references leaf %llu, data list %#llx",
2007 root_node->val, ref_node->val,
2009 ret = iterate_leaf_refs(fs_info,
2010 (struct extent_inode_elem *)
2011 (uintptr_t)ref_node->aux,
2013 extent_item_objectid,
2019 free_leaf_list(refs);
2022 btrfs_put_tree_mod_seq(fs_info, &seq_elem);
2023 btrfs_end_transaction(trans);
2025 up_read(&fs_info->commit_root_sem);
2031 static int build_ino_list(u64 inum, u64 offset, u64 root, void *ctx)
2033 struct btrfs_data_container *inodes = ctx;
2034 const size_t c = 3 * sizeof(u64);
2036 if (inodes->bytes_left >= c) {
2037 inodes->bytes_left -= c;
2038 inodes->val[inodes->elem_cnt] = inum;
2039 inodes->val[inodes->elem_cnt + 1] = offset;
2040 inodes->val[inodes->elem_cnt + 2] = root;
2041 inodes->elem_cnt += 3;
2043 inodes->bytes_missing += c - inodes->bytes_left;
2044 inodes->bytes_left = 0;
2045 inodes->elem_missed += 3;
2051 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
2052 struct btrfs_path *path,
2053 void *ctx, bool ignore_offset)
2056 u64 extent_item_pos;
2058 struct btrfs_key found_key;
2059 int search_commit_root = path->search_commit_root;
2061 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
2062 btrfs_release_path(path);
2065 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2068 extent_item_pos = logical - found_key.objectid;
2069 ret = iterate_extent_inodes(fs_info, found_key.objectid,
2070 extent_item_pos, search_commit_root,
2071 build_ino_list, ctx, ignore_offset);
2076 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2077 struct extent_buffer *eb, struct inode_fs_paths *ipath);
2079 static int iterate_inode_refs(u64 inum, struct inode_fs_paths *ipath)
2088 struct btrfs_root *fs_root = ipath->fs_root;
2089 struct btrfs_path *path = ipath->btrfs_path;
2090 struct extent_buffer *eb;
2091 struct btrfs_inode_ref *iref;
2092 struct btrfs_key found_key;
2095 ret = btrfs_find_item(fs_root, path, inum,
2096 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2102 ret = found ? 0 : -ENOENT;
2107 parent = found_key.offset;
2108 slot = path->slots[0];
2109 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2114 btrfs_release_path(path);
2116 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2118 for (cur = 0; cur < btrfs_item_size(eb, slot); cur += len) {
2119 name_len = btrfs_inode_ref_name_len(eb, iref);
2120 /* path must be released before calling iterate()! */
2121 btrfs_debug(fs_root->fs_info,
2122 "following ref at offset %u for inode %llu in tree %llu",
2123 cur, found_key.objectid,
2124 fs_root->root_key.objectid);
2125 ret = inode_to_path(parent, name_len,
2126 (unsigned long)(iref + 1), eb, ipath);
2129 len = sizeof(*iref) + name_len;
2130 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2132 free_extent_buffer(eb);
2135 btrfs_release_path(path);
2140 static int iterate_inode_extrefs(u64 inum, struct inode_fs_paths *ipath)
2147 struct btrfs_root *fs_root = ipath->fs_root;
2148 struct btrfs_path *path = ipath->btrfs_path;
2149 struct extent_buffer *eb;
2150 struct btrfs_inode_extref *extref;
2156 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2161 ret = found ? 0 : -ENOENT;
2166 slot = path->slots[0];
2167 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2172 btrfs_release_path(path);
2174 item_size = btrfs_item_size(eb, slot);
2175 ptr = btrfs_item_ptr_offset(eb, slot);
2178 while (cur_offset < item_size) {
2181 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2182 parent = btrfs_inode_extref_parent(eb, extref);
2183 name_len = btrfs_inode_extref_name_len(eb, extref);
2184 ret = inode_to_path(parent, name_len,
2185 (unsigned long)&extref->name, eb, ipath);
2189 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2190 cur_offset += sizeof(*extref);
2192 free_extent_buffer(eb);
2197 btrfs_release_path(path);
2203 * returns 0 if the path could be dumped (probably truncated)
2204 * returns <0 in case of an error
2206 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2207 struct extent_buffer *eb, struct inode_fs_paths *ipath)
2211 int i = ipath->fspath->elem_cnt;
2212 const int s_ptr = sizeof(char *);
2215 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2216 ipath->fspath->bytes_left - s_ptr : 0;
2218 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2219 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2220 name_off, eb, inum, fspath_min, bytes_left);
2222 return PTR_ERR(fspath);
2224 if (fspath > fspath_min) {
2225 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2226 ++ipath->fspath->elem_cnt;
2227 ipath->fspath->bytes_left = fspath - fspath_min;
2229 ++ipath->fspath->elem_missed;
2230 ipath->fspath->bytes_missing += fspath_min - fspath;
2231 ipath->fspath->bytes_left = 0;
2238 * this dumps all file system paths to the inode into the ipath struct, provided
2239 * is has been created large enough. each path is zero-terminated and accessed
2240 * from ipath->fspath->val[i].
2241 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2242 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2243 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2244 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2245 * have been needed to return all paths.
2247 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2252 ret = iterate_inode_refs(inum, ipath);
2255 else if (ret != -ENOENT)
2258 ret = iterate_inode_extrefs(inum, ipath);
2259 if (ret == -ENOENT && found_refs)
2265 struct btrfs_data_container *init_data_container(u32 total_bytes)
2267 struct btrfs_data_container *data;
2270 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2271 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2273 return ERR_PTR(-ENOMEM);
2275 if (total_bytes >= sizeof(*data)) {
2276 data->bytes_left = total_bytes - sizeof(*data);
2277 data->bytes_missing = 0;
2279 data->bytes_missing = sizeof(*data) - total_bytes;
2280 data->bytes_left = 0;
2284 data->elem_missed = 0;
2290 * allocates space to return multiple file system paths for an inode.
2291 * total_bytes to allocate are passed, note that space usable for actual path
2292 * information will be total_bytes - sizeof(struct inode_fs_paths).
2293 * the returned pointer must be freed with free_ipath() in the end.
2295 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2296 struct btrfs_path *path)
2298 struct inode_fs_paths *ifp;
2299 struct btrfs_data_container *fspath;
2301 fspath = init_data_container(total_bytes);
2303 return ERR_CAST(fspath);
2305 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2308 return ERR_PTR(-ENOMEM);
2311 ifp->btrfs_path = path;
2312 ifp->fspath = fspath;
2313 ifp->fs_root = fs_root;
2318 void free_ipath(struct inode_fs_paths *ipath)
2322 kvfree(ipath->fspath);
2326 struct btrfs_backref_iter *btrfs_backref_iter_alloc(
2327 struct btrfs_fs_info *fs_info, gfp_t gfp_flag)
2329 struct btrfs_backref_iter *ret;
2331 ret = kzalloc(sizeof(*ret), gfp_flag);
2335 ret->path = btrfs_alloc_path();
2341 /* Current backref iterator only supports iteration in commit root */
2342 ret->path->search_commit_root = 1;
2343 ret->path->skip_locking = 1;
2344 ret->fs_info = fs_info;
2349 int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr)
2351 struct btrfs_fs_info *fs_info = iter->fs_info;
2352 struct btrfs_root *extent_root = btrfs_extent_root(fs_info, bytenr);
2353 struct btrfs_path *path = iter->path;
2354 struct btrfs_extent_item *ei;
2355 struct btrfs_key key;
2358 key.objectid = bytenr;
2359 key.type = BTRFS_METADATA_ITEM_KEY;
2360 key.offset = (u64)-1;
2361 iter->bytenr = bytenr;
2363 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
2370 if (path->slots[0] == 0) {
2371 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
2377 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
2378 if ((key.type != BTRFS_EXTENT_ITEM_KEY &&
2379 key.type != BTRFS_METADATA_ITEM_KEY) || key.objectid != bytenr) {
2383 memcpy(&iter->cur_key, &key, sizeof(key));
2384 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2386 iter->end_ptr = (u32)(iter->item_ptr +
2387 btrfs_item_size(path->nodes[0], path->slots[0]));
2388 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
2389 struct btrfs_extent_item);
2392 * Only support iteration on tree backref yet.
2394 * This is an extra precaution for non skinny-metadata, where
2395 * EXTENT_ITEM is also used for tree blocks, that we can only use
2396 * extent flags to determine if it's a tree block.
2398 if (btrfs_extent_flags(path->nodes[0], ei) & BTRFS_EXTENT_FLAG_DATA) {
2402 iter->cur_ptr = (u32)(iter->item_ptr + sizeof(*ei));
2404 /* If there is no inline backref, go search for keyed backref */
2405 if (iter->cur_ptr >= iter->end_ptr) {
2406 ret = btrfs_next_item(extent_root, path);
2408 /* No inline nor keyed ref */
2416 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key,
2418 if (iter->cur_key.objectid != bytenr ||
2419 (iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY &&
2420 iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY)) {
2424 iter->cur_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2426 iter->item_ptr = iter->cur_ptr;
2427 iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size(
2428 path->nodes[0], path->slots[0]));
2433 btrfs_backref_iter_release(iter);
2438 * Go to the next backref item of current bytenr, can be either inlined or
2441 * Caller needs to check whether it's inline ref or not by iter->cur_key.
2443 * Return 0 if we get next backref without problem.
2444 * Return >0 if there is no extra backref for this bytenr.
2445 * Return <0 if there is something wrong happened.
2447 int btrfs_backref_iter_next(struct btrfs_backref_iter *iter)
2449 struct extent_buffer *eb = btrfs_backref_get_eb(iter);
2450 struct btrfs_root *extent_root;
2451 struct btrfs_path *path = iter->path;
2452 struct btrfs_extent_inline_ref *iref;
2456 if (btrfs_backref_iter_is_inline_ref(iter)) {
2457 /* We're still inside the inline refs */
2458 ASSERT(iter->cur_ptr < iter->end_ptr);
2460 if (btrfs_backref_has_tree_block_info(iter)) {
2461 /* First tree block info */
2462 size = sizeof(struct btrfs_tree_block_info);
2464 /* Use inline ref type to determine the size */
2467 iref = (struct btrfs_extent_inline_ref *)
2468 ((unsigned long)iter->cur_ptr);
2469 type = btrfs_extent_inline_ref_type(eb, iref);
2471 size = btrfs_extent_inline_ref_size(type);
2473 iter->cur_ptr += size;
2474 if (iter->cur_ptr < iter->end_ptr)
2477 /* All inline items iterated, fall through */
2480 /* We're at keyed items, there is no inline item, go to the next one */
2481 extent_root = btrfs_extent_root(iter->fs_info, iter->bytenr);
2482 ret = btrfs_next_item(extent_root, iter->path);
2486 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]);
2487 if (iter->cur_key.objectid != iter->bytenr ||
2488 (iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY &&
2489 iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY))
2491 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2493 iter->cur_ptr = iter->item_ptr;
2494 iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size(path->nodes[0],
2499 void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
2500 struct btrfs_backref_cache *cache, int is_reloc)
2504 cache->rb_root = RB_ROOT;
2505 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
2506 INIT_LIST_HEAD(&cache->pending[i]);
2507 INIT_LIST_HEAD(&cache->changed);
2508 INIT_LIST_HEAD(&cache->detached);
2509 INIT_LIST_HEAD(&cache->leaves);
2510 INIT_LIST_HEAD(&cache->pending_edge);
2511 INIT_LIST_HEAD(&cache->useless_node);
2512 cache->fs_info = fs_info;
2513 cache->is_reloc = is_reloc;
2516 struct btrfs_backref_node *btrfs_backref_alloc_node(
2517 struct btrfs_backref_cache *cache, u64 bytenr, int level)
2519 struct btrfs_backref_node *node;
2521 ASSERT(level >= 0 && level < BTRFS_MAX_LEVEL);
2522 node = kzalloc(sizeof(*node), GFP_NOFS);
2526 INIT_LIST_HEAD(&node->list);
2527 INIT_LIST_HEAD(&node->upper);
2528 INIT_LIST_HEAD(&node->lower);
2529 RB_CLEAR_NODE(&node->rb_node);
2531 node->level = level;
2532 node->bytenr = bytenr;
2537 struct btrfs_backref_edge *btrfs_backref_alloc_edge(
2538 struct btrfs_backref_cache *cache)
2540 struct btrfs_backref_edge *edge;
2542 edge = kzalloc(sizeof(*edge), GFP_NOFS);
2549 * Drop the backref node from cache, also cleaning up all its
2550 * upper edges and any uncached nodes in the path.
2552 * This cleanup happens bottom up, thus the node should either
2553 * be the lowest node in the cache or a detached node.
2555 void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
2556 struct btrfs_backref_node *node)
2558 struct btrfs_backref_node *upper;
2559 struct btrfs_backref_edge *edge;
2564 BUG_ON(!node->lowest && !node->detached);
2565 while (!list_empty(&node->upper)) {
2566 edge = list_entry(node->upper.next, struct btrfs_backref_edge,
2568 upper = edge->node[UPPER];
2569 list_del(&edge->list[LOWER]);
2570 list_del(&edge->list[UPPER]);
2571 btrfs_backref_free_edge(cache, edge);
2574 * Add the node to leaf node list if no other child block
2577 if (list_empty(&upper->lower)) {
2578 list_add_tail(&upper->lower, &cache->leaves);
2583 btrfs_backref_drop_node(cache, node);
2587 * Release all nodes/edges from current cache
2589 void btrfs_backref_release_cache(struct btrfs_backref_cache *cache)
2591 struct btrfs_backref_node *node;
2594 while (!list_empty(&cache->detached)) {
2595 node = list_entry(cache->detached.next,
2596 struct btrfs_backref_node, list);
2597 btrfs_backref_cleanup_node(cache, node);
2600 while (!list_empty(&cache->leaves)) {
2601 node = list_entry(cache->leaves.next,
2602 struct btrfs_backref_node, lower);
2603 btrfs_backref_cleanup_node(cache, node);
2606 cache->last_trans = 0;
2608 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
2609 ASSERT(list_empty(&cache->pending[i]));
2610 ASSERT(list_empty(&cache->pending_edge));
2611 ASSERT(list_empty(&cache->useless_node));
2612 ASSERT(list_empty(&cache->changed));
2613 ASSERT(list_empty(&cache->detached));
2614 ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
2615 ASSERT(!cache->nr_nodes);
2616 ASSERT(!cache->nr_edges);
2620 * Handle direct tree backref
2622 * Direct tree backref means, the backref item shows its parent bytenr
2623 * directly. This is for SHARED_BLOCK_REF backref (keyed or inlined).
2625 * @ref_key: The converted backref key.
2626 * For keyed backref, it's the item key.
2627 * For inlined backref, objectid is the bytenr,
2628 * type is btrfs_inline_ref_type, offset is
2629 * btrfs_inline_ref_offset.
2631 static int handle_direct_tree_backref(struct btrfs_backref_cache *cache,
2632 struct btrfs_key *ref_key,
2633 struct btrfs_backref_node *cur)
2635 struct btrfs_backref_edge *edge;
2636 struct btrfs_backref_node *upper;
2637 struct rb_node *rb_node;
2639 ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY);
2641 /* Only reloc root uses backref pointing to itself */
2642 if (ref_key->objectid == ref_key->offset) {
2643 struct btrfs_root *root;
2645 cur->is_reloc_root = 1;
2646 /* Only reloc backref cache cares about a specific root */
2647 if (cache->is_reloc) {
2648 root = find_reloc_root(cache->fs_info, cur->bytenr);
2654 * For generic purpose backref cache, reloc root node
2657 list_add(&cur->list, &cache->useless_node);
2662 edge = btrfs_backref_alloc_edge(cache);
2666 rb_node = rb_simple_search(&cache->rb_root, ref_key->offset);
2668 /* Parent node not yet cached */
2669 upper = btrfs_backref_alloc_node(cache, ref_key->offset,
2672 btrfs_backref_free_edge(cache, edge);
2677 * Backrefs for the upper level block isn't cached, add the
2678 * block to pending list
2680 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
2682 /* Parent node already cached */
2683 upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
2684 ASSERT(upper->checked);
2685 INIT_LIST_HEAD(&edge->list[UPPER]);
2687 btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER);
2692 * Handle indirect tree backref
2694 * Indirect tree backref means, we only know which tree the node belongs to.
2695 * We still need to do a tree search to find out the parents. This is for
2696 * TREE_BLOCK_REF backref (keyed or inlined).
2698 * @ref_key: The same as @ref_key in handle_direct_tree_backref()
2699 * @tree_key: The first key of this tree block.
2700 * @path: A clean (released) path, to avoid allocating path every time
2701 * the function get called.
2703 static int handle_indirect_tree_backref(struct btrfs_backref_cache *cache,
2704 struct btrfs_path *path,
2705 struct btrfs_key *ref_key,
2706 struct btrfs_key *tree_key,
2707 struct btrfs_backref_node *cur)
2709 struct btrfs_fs_info *fs_info = cache->fs_info;
2710 struct btrfs_backref_node *upper;
2711 struct btrfs_backref_node *lower;
2712 struct btrfs_backref_edge *edge;
2713 struct extent_buffer *eb;
2714 struct btrfs_root *root;
2715 struct rb_node *rb_node;
2717 bool need_check = true;
2720 root = btrfs_get_fs_root(fs_info, ref_key->offset, false);
2722 return PTR_ERR(root);
2723 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
2726 if (btrfs_root_level(&root->root_item) == cur->level) {
2728 ASSERT(btrfs_root_bytenr(&root->root_item) == cur->bytenr);
2730 * For reloc backref cache, we may ignore reloc root. But for
2731 * general purpose backref cache, we can't rely on
2732 * btrfs_should_ignore_reloc_root() as it may conflict with
2733 * current running relocation and lead to missing root.
2735 * For general purpose backref cache, reloc root detection is
2736 * completely relying on direct backref (key->offset is parent
2737 * bytenr), thus only do such check for reloc cache.
2739 if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) {
2740 btrfs_put_root(root);
2741 list_add(&cur->list, &cache->useless_node);
2748 level = cur->level + 1;
2750 /* Search the tree to find parent blocks referring to the block */
2751 path->search_commit_root = 1;
2752 path->skip_locking = 1;
2753 path->lowest_level = level;
2754 ret = btrfs_search_slot(NULL, root, tree_key, path, 0, 0);
2755 path->lowest_level = 0;
2757 btrfs_put_root(root);
2760 if (ret > 0 && path->slots[level] > 0)
2761 path->slots[level]--;
2763 eb = path->nodes[level];
2764 if (btrfs_node_blockptr(eb, path->slots[level]) != cur->bytenr) {
2766 "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
2767 cur->bytenr, level - 1, root->root_key.objectid,
2768 tree_key->objectid, tree_key->type, tree_key->offset);
2769 btrfs_put_root(root);
2775 /* Add all nodes and edges in the path */
2776 for (; level < BTRFS_MAX_LEVEL; level++) {
2777 if (!path->nodes[level]) {
2778 ASSERT(btrfs_root_bytenr(&root->root_item) ==
2780 /* Same as previous should_ignore_reloc_root() call */
2781 if (btrfs_should_ignore_reloc_root(root) &&
2783 btrfs_put_root(root);
2784 list_add(&lower->list, &cache->useless_node);
2791 edge = btrfs_backref_alloc_edge(cache);
2793 btrfs_put_root(root);
2798 eb = path->nodes[level];
2799 rb_node = rb_simple_search(&cache->rb_root, eb->start);
2801 upper = btrfs_backref_alloc_node(cache, eb->start,
2804 btrfs_put_root(root);
2805 btrfs_backref_free_edge(cache, edge);
2809 upper->owner = btrfs_header_owner(eb);
2810 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
2814 * If we know the block isn't shared we can avoid
2815 * checking its backrefs.
2817 if (btrfs_block_can_be_shared(root, eb))
2823 * Add the block to pending list if we need to check its
2824 * backrefs, we only do this once while walking up a
2825 * tree as we will catch anything else later on.
2827 if (!upper->checked && need_check) {
2829 list_add_tail(&edge->list[UPPER],
2830 &cache->pending_edge);
2834 INIT_LIST_HEAD(&edge->list[UPPER]);
2837 upper = rb_entry(rb_node, struct btrfs_backref_node,
2839 ASSERT(upper->checked);
2840 INIT_LIST_HEAD(&edge->list[UPPER]);
2842 upper->owner = btrfs_header_owner(eb);
2844 btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER);
2847 btrfs_put_root(root);
2854 btrfs_release_path(path);
2859 * Add backref node @cur into @cache.
2861 * NOTE: Even if the function returned 0, @cur is not yet cached as its upper
2862 * links aren't yet bi-directional. Needs to finish such links.
2863 * Use btrfs_backref_finish_upper_links() to finish such linkage.
2865 * @path: Released path for indirect tree backref lookup
2866 * @iter: Released backref iter for extent tree search
2867 * @node_key: The first key of the tree block
2869 int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
2870 struct btrfs_path *path,
2871 struct btrfs_backref_iter *iter,
2872 struct btrfs_key *node_key,
2873 struct btrfs_backref_node *cur)
2875 struct btrfs_fs_info *fs_info = cache->fs_info;
2876 struct btrfs_backref_edge *edge;
2877 struct btrfs_backref_node *exist;
2880 ret = btrfs_backref_iter_start(iter, cur->bytenr);
2884 * We skip the first btrfs_tree_block_info, as we don't use the key
2885 * stored in it, but fetch it from the tree block
2887 if (btrfs_backref_has_tree_block_info(iter)) {
2888 ret = btrfs_backref_iter_next(iter);
2891 /* No extra backref? This means the tree block is corrupted */
2897 WARN_ON(cur->checked);
2898 if (!list_empty(&cur->upper)) {
2900 * The backref was added previously when processing backref of
2901 * type BTRFS_TREE_BLOCK_REF_KEY
2903 ASSERT(list_is_singular(&cur->upper));
2904 edge = list_entry(cur->upper.next, struct btrfs_backref_edge,
2906 ASSERT(list_empty(&edge->list[UPPER]));
2907 exist = edge->node[UPPER];
2909 * Add the upper level block to pending list if we need check
2912 if (!exist->checked)
2913 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
2918 for (; ret == 0; ret = btrfs_backref_iter_next(iter)) {
2919 struct extent_buffer *eb;
2920 struct btrfs_key key;
2924 eb = btrfs_backref_get_eb(iter);
2926 key.objectid = iter->bytenr;
2927 if (btrfs_backref_iter_is_inline_ref(iter)) {
2928 struct btrfs_extent_inline_ref *iref;
2930 /* Update key for inline backref */
2931 iref = (struct btrfs_extent_inline_ref *)
2932 ((unsigned long)iter->cur_ptr);
2933 type = btrfs_get_extent_inline_ref_type(eb, iref,
2934 BTRFS_REF_TYPE_BLOCK);
2935 if (type == BTRFS_REF_TYPE_INVALID) {
2940 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
2942 key.type = iter->cur_key.type;
2943 key.offset = iter->cur_key.offset;
2947 * Parent node found and matches current inline ref, no need to
2948 * rebuild this node for this inline ref
2951 ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
2952 exist->owner == key.offset) ||
2953 (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
2954 exist->bytenr == key.offset))) {
2959 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */
2960 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
2961 ret = handle_direct_tree_backref(cache, &key, cur);
2965 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
2967 btrfs_print_v0_err(fs_info);
2968 btrfs_handle_fs_error(fs_info, ret, NULL);
2970 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
2975 * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset
2976 * means the root objectid. We need to search the tree to get
2977 * its parent bytenr.
2979 ret = handle_indirect_tree_backref(cache, path, &key, node_key,
2988 btrfs_backref_iter_release(iter);
2993 * Finish the upwards linkage created by btrfs_backref_add_tree_node()
2995 int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
2996 struct btrfs_backref_node *start)
2998 struct list_head *useless_node = &cache->useless_node;
2999 struct btrfs_backref_edge *edge;
3000 struct rb_node *rb_node;
3001 LIST_HEAD(pending_edge);
3003 ASSERT(start->checked);
3005 /* Insert this node to cache if it's not COW-only */
3006 if (!start->cowonly) {
3007 rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
3010 btrfs_backref_panic(cache->fs_info, start->bytenr,
3012 list_add_tail(&start->lower, &cache->leaves);
3016 * Use breadth first search to iterate all related edges.
3018 * The starting points are all the edges of this node
3020 list_for_each_entry(edge, &start->upper, list[LOWER])
3021 list_add_tail(&edge->list[UPPER], &pending_edge);
3023 while (!list_empty(&pending_edge)) {
3024 struct btrfs_backref_node *upper;
3025 struct btrfs_backref_node *lower;
3027 edge = list_first_entry(&pending_edge,
3028 struct btrfs_backref_edge, list[UPPER]);
3029 list_del_init(&edge->list[UPPER]);
3030 upper = edge->node[UPPER];
3031 lower = edge->node[LOWER];
3033 /* Parent is detached, no need to keep any edges */
3034 if (upper->detached) {
3035 list_del(&edge->list[LOWER]);
3036 btrfs_backref_free_edge(cache, edge);
3038 /* Lower node is orphan, queue for cleanup */
3039 if (list_empty(&lower->upper))
3040 list_add(&lower->list, useless_node);
3045 * All new nodes added in current build_backref_tree() haven't
3046 * been linked to the cache rb tree.
3047 * So if we have upper->rb_node populated, this means a cache
3048 * hit. We only need to link the edge, as @upper and all its
3049 * parents have already been linked.
3051 if (!RB_EMPTY_NODE(&upper->rb_node)) {
3052 if (upper->lowest) {
3053 list_del_init(&upper->lower);
3057 list_add_tail(&edge->list[UPPER], &upper->lower);
3061 /* Sanity check, we shouldn't have any unchecked nodes */
3062 if (!upper->checked) {
3067 /* Sanity check, COW-only node has non-COW-only parent */
3068 if (start->cowonly != upper->cowonly) {
3073 /* Only cache non-COW-only (subvolume trees) tree blocks */
3074 if (!upper->cowonly) {
3075 rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
3078 btrfs_backref_panic(cache->fs_info,
3079 upper->bytenr, -EEXIST);
3084 list_add_tail(&edge->list[UPPER], &upper->lower);
3087 * Also queue all the parent edges of this uncached node
3088 * to finish the upper linkage
3090 list_for_each_entry(edge, &upper->upper, list[LOWER])
3091 list_add_tail(&edge->list[UPPER], &pending_edge);
3096 void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
3097 struct btrfs_backref_node *node)
3099 struct btrfs_backref_node *lower;
3100 struct btrfs_backref_node *upper;
3101 struct btrfs_backref_edge *edge;
3103 while (!list_empty(&cache->useless_node)) {
3104 lower = list_first_entry(&cache->useless_node,
3105 struct btrfs_backref_node, list);
3106 list_del_init(&lower->list);
3108 while (!list_empty(&cache->pending_edge)) {
3109 edge = list_first_entry(&cache->pending_edge,
3110 struct btrfs_backref_edge, list[UPPER]);
3111 list_del(&edge->list[UPPER]);
3112 list_del(&edge->list[LOWER]);
3113 lower = edge->node[LOWER];
3114 upper = edge->node[UPPER];
3115 btrfs_backref_free_edge(cache, edge);
3118 * Lower is no longer linked to any upper backref nodes and
3119 * isn't in the cache, we can free it ourselves.
3121 if (list_empty(&lower->upper) &&
3122 RB_EMPTY_NODE(&lower->rb_node))
3123 list_add(&lower->list, &cache->useless_node);
3125 if (!RB_EMPTY_NODE(&upper->rb_node))
3128 /* Add this guy's upper edges to the list to process */
3129 list_for_each_entry(edge, &upper->upper, list[LOWER])
3130 list_add_tail(&edge->list[UPPER],
3131 &cache->pending_edge);
3132 if (list_empty(&upper->upper))
3133 list_add(&upper->list, &cache->useless_node);
3136 while (!list_empty(&cache->useless_node)) {
3137 lower = list_first_entry(&cache->useless_node,
3138 struct btrfs_backref_node, list);
3139 list_del_init(&lower->list);
3142 btrfs_backref_drop_node(cache, lower);
3145 btrfs_backref_cleanup_node(cache, node);
3146 ASSERT(list_empty(&cache->useless_node) &&
3147 list_empty(&cache->pending_edge));