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
141 bool have_delayed_delete_refs;
144 static inline int extent_is_shared(struct share_check *sc)
146 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
149 static struct kmem_cache *btrfs_prelim_ref_cache;
151 int __init btrfs_prelim_ref_init(void)
153 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
154 sizeof(struct prelim_ref),
158 if (!btrfs_prelim_ref_cache)
163 void __cold btrfs_prelim_ref_exit(void)
165 kmem_cache_destroy(btrfs_prelim_ref_cache);
168 static void free_pref(struct prelim_ref *ref)
170 kmem_cache_free(btrfs_prelim_ref_cache, ref);
174 * Return 0 when both refs are for the same block (and can be merged).
175 * A -1 return indicates ref1 is a 'lower' block than ref2, while 1
176 * indicates a 'higher' block.
178 static int prelim_ref_compare(struct prelim_ref *ref1,
179 struct prelim_ref *ref2)
181 if (ref1->level < ref2->level)
183 if (ref1->level > ref2->level)
185 if (ref1->root_id < ref2->root_id)
187 if (ref1->root_id > ref2->root_id)
189 if (ref1->key_for_search.type < ref2->key_for_search.type)
191 if (ref1->key_for_search.type > ref2->key_for_search.type)
193 if (ref1->key_for_search.objectid < ref2->key_for_search.objectid)
195 if (ref1->key_for_search.objectid > ref2->key_for_search.objectid)
197 if (ref1->key_for_search.offset < ref2->key_for_search.offset)
199 if (ref1->key_for_search.offset > ref2->key_for_search.offset)
201 if (ref1->parent < ref2->parent)
203 if (ref1->parent > ref2->parent)
209 static void update_share_count(struct share_check *sc, int oldcount,
212 if ((!sc) || (oldcount == 0 && newcount < 1))
215 if (oldcount > 0 && newcount < 1)
217 else if (oldcount < 1 && newcount > 0)
222 * Add @newref to the @root rbtree, merging identical refs.
224 * Callers should assume that newref has been freed after calling.
226 static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
227 struct preftree *preftree,
228 struct prelim_ref *newref,
229 struct share_check *sc)
231 struct rb_root_cached *root;
233 struct rb_node *parent = NULL;
234 struct prelim_ref *ref;
236 bool leftmost = true;
238 root = &preftree->root;
239 p = &root->rb_root.rb_node;
243 ref = rb_entry(parent, struct prelim_ref, rbnode);
244 result = prelim_ref_compare(ref, newref);
247 } else if (result > 0) {
251 /* Identical refs, merge them and free @newref */
252 struct extent_inode_elem *eie = ref->inode_list;
254 while (eie && eie->next)
258 ref->inode_list = newref->inode_list;
260 eie->next = newref->inode_list;
261 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
264 * A delayed ref can have newref->count < 0.
265 * The ref->count is updated to follow any
266 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
268 update_share_count(sc, ref->count,
269 ref->count + newref->count);
270 ref->count += newref->count;
276 update_share_count(sc, 0, newref->count);
278 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
279 rb_link_node(&newref->rbnode, parent, p);
280 rb_insert_color_cached(&newref->rbnode, root, leftmost);
284 * Release the entire tree. We don't care about internal consistency so
285 * just free everything and then reset the tree root.
287 static void prelim_release(struct preftree *preftree)
289 struct prelim_ref *ref, *next_ref;
291 rbtree_postorder_for_each_entry_safe(ref, next_ref,
292 &preftree->root.rb_root, rbnode)
295 preftree->root = RB_ROOT_CACHED;
300 * the rules for all callers of this function are:
301 * - obtaining the parent is the goal
302 * - if you add a key, you must know that it is a correct key
303 * - if you cannot add the parent or a correct key, then we will look into the
304 * block later to set a correct key
308 * backref type | shared | indirect | shared | indirect
309 * information | tree | tree | data | data
310 * --------------------+--------+----------+--------+----------
311 * parent logical | y | - | - | -
312 * key to resolve | - | y | y | y
313 * tree block logical | - | - | - | -
314 * root for resolving | y | y | y | y
316 * - column 1: we've the parent -> done
317 * - column 2, 3, 4: we use the key to find the parent
319 * on disk refs (inline or keyed)
320 * ==============================
321 * backref type | shared | indirect | shared | indirect
322 * information | tree | tree | data | data
323 * --------------------+--------+----------+--------+----------
324 * parent logical | y | - | y | -
325 * key to resolve | - | - | - | y
326 * tree block logical | y | y | y | y
327 * root for resolving | - | y | y | y
329 * - column 1, 3: we've the parent -> done
330 * - column 2: we take the first key from the block to find the parent
331 * (see add_missing_keys)
332 * - column 4: we use the key to find the parent
334 * additional information that's available but not required to find the parent
335 * block might help in merging entries to gain some speed.
337 static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
338 struct preftree *preftree, u64 root_id,
339 const struct btrfs_key *key, int level, u64 parent,
340 u64 wanted_disk_byte, int count,
341 struct share_check *sc, gfp_t gfp_mask)
343 struct prelim_ref *ref;
345 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
348 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
352 ref->root_id = root_id;
354 ref->key_for_search = *key;
356 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
358 ref->inode_list = NULL;
361 ref->parent = parent;
362 ref->wanted_disk_byte = wanted_disk_byte;
363 prelim_ref_insert(fs_info, preftree, ref, sc);
364 return extent_is_shared(sc);
367 /* direct refs use root == 0, key == NULL */
368 static int add_direct_ref(const struct btrfs_fs_info *fs_info,
369 struct preftrees *preftrees, int level, u64 parent,
370 u64 wanted_disk_byte, int count,
371 struct share_check *sc, gfp_t gfp_mask)
373 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
374 parent, wanted_disk_byte, count, sc, gfp_mask);
377 /* indirect refs use parent == 0 */
378 static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
379 struct preftrees *preftrees, u64 root_id,
380 const struct btrfs_key *key, int level,
381 u64 wanted_disk_byte, int count,
382 struct share_check *sc, gfp_t gfp_mask)
384 struct preftree *tree = &preftrees->indirect;
387 tree = &preftrees->indirect_missing_keys;
388 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
389 wanted_disk_byte, count, sc, gfp_mask);
392 static int is_shared_data_backref(struct preftrees *preftrees, u64 bytenr)
394 struct rb_node **p = &preftrees->direct.root.rb_root.rb_node;
395 struct rb_node *parent = NULL;
396 struct prelim_ref *ref = NULL;
397 struct prelim_ref target = {};
400 target.parent = bytenr;
404 ref = rb_entry(parent, struct prelim_ref, rbnode);
405 result = prelim_ref_compare(ref, &target);
417 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
418 struct ulist *parents,
419 struct preftrees *preftrees, struct prelim_ref *ref,
420 int level, u64 time_seq, const u64 *extent_item_pos,
425 struct extent_buffer *eb;
426 struct btrfs_key key;
427 struct btrfs_key *key_for_search = &ref->key_for_search;
428 struct btrfs_file_extent_item *fi;
429 struct extent_inode_elem *eie = NULL, *old = NULL;
431 u64 wanted_disk_byte = ref->wanted_disk_byte;
436 eb = path->nodes[level];
437 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
444 * 1. We normally enter this function with the path already pointing to
445 * the first item to check. But sometimes, we may enter it with
447 * 2. We are searching for normal backref but bytenr of this leaf
448 * matches shared data backref
449 * 3. The leaf owner is not equal to the root we are searching
451 * For these cases, go to the next leaf before we continue.
454 if (path->slots[0] >= btrfs_header_nritems(eb) ||
455 is_shared_data_backref(preftrees, eb->start) ||
456 ref->root_id != btrfs_header_owner(eb)) {
457 if (time_seq == BTRFS_SEQ_LAST)
458 ret = btrfs_next_leaf(root, path);
460 ret = btrfs_next_old_leaf(root, path, time_seq);
463 while (!ret && count < ref->count) {
465 slot = path->slots[0];
467 btrfs_item_key_to_cpu(eb, &key, slot);
469 if (key.objectid != key_for_search->objectid ||
470 key.type != BTRFS_EXTENT_DATA_KEY)
474 * We are searching for normal backref but bytenr of this leaf
475 * matches shared data backref, OR
476 * the leaf owner is not equal to the root we are searching for
479 (is_shared_data_backref(preftrees, eb->start) ||
480 ref->root_id != btrfs_header_owner(eb))) {
481 if (time_seq == BTRFS_SEQ_LAST)
482 ret = btrfs_next_leaf(root, path);
484 ret = btrfs_next_old_leaf(root, path, time_seq);
487 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
488 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
489 data_offset = btrfs_file_extent_offset(eb, fi);
491 if (disk_byte == wanted_disk_byte) {
494 if (ref->key_for_search.offset == key.offset - data_offset)
498 if (extent_item_pos) {
499 ret = check_extent_in_eb(&key, eb, fi,
501 &eie, ignore_offset);
507 ret = ulist_add_merge_ptr(parents, eb->start,
508 eie, (void **)&old, GFP_NOFS);
511 if (!ret && extent_item_pos) {
519 if (time_seq == BTRFS_SEQ_LAST)
520 ret = btrfs_next_item(root, path);
522 ret = btrfs_next_old_item(root, path, time_seq);
528 free_inode_elem_list(eie);
533 * resolve an indirect backref in the form (root_id, key, level)
534 * to a logical address
536 static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
537 struct btrfs_path *path, u64 time_seq,
538 struct preftrees *preftrees,
539 struct prelim_ref *ref, struct ulist *parents,
540 const u64 *extent_item_pos, bool ignore_offset)
542 struct btrfs_root *root;
543 struct extent_buffer *eb;
546 int level = ref->level;
547 struct btrfs_key search_key = ref->key_for_search;
550 * If we're search_commit_root we could possibly be holding locks on
551 * other tree nodes. This happens when qgroups does backref walks when
552 * adding new delayed refs. To deal with this we need to look in cache
553 * for the root, and if we don't find it then we need to search the
554 * tree_root's commit root, thus the btrfs_get_fs_root_commit_root usage
557 if (path->search_commit_root)
558 root = btrfs_get_fs_root_commit_root(fs_info, path, ref->root_id);
560 root = btrfs_get_fs_root(fs_info, ref->root_id, false);
566 if (!path->search_commit_root &&
567 test_bit(BTRFS_ROOT_DELETING, &root->state)) {
572 if (btrfs_is_testing(fs_info)) {
577 if (path->search_commit_root)
578 root_level = btrfs_header_level(root->commit_root);
579 else if (time_seq == BTRFS_SEQ_LAST)
580 root_level = btrfs_header_level(root->node);
582 root_level = btrfs_old_root_level(root, time_seq);
584 if (root_level + 1 == level)
588 * We can often find data backrefs with an offset that is too large
589 * (>= LLONG_MAX, maximum allowed file offset) due to underflows when
590 * subtracting a file's offset with the data offset of its
591 * corresponding extent data item. This can happen for example in the
594 * So if we detect such case we set the search key's offset to zero to
595 * make sure we will find the matching file extent item at
596 * add_all_parents(), otherwise we will miss it because the offset
597 * taken form the backref is much larger then the offset of the file
598 * extent item. This can make us scan a very large number of file
599 * extent items, but at least it will not make us miss any.
601 * This is an ugly workaround for a behaviour that should have never
602 * existed, but it does and a fix for the clone ioctl would touch a lot
603 * of places, cause backwards incompatibility and would not fix the
604 * problem for extents cloned with older kernels.
606 if (search_key.type == BTRFS_EXTENT_DATA_KEY &&
607 search_key.offset >= LLONG_MAX)
608 search_key.offset = 0;
609 path->lowest_level = level;
610 if (time_seq == BTRFS_SEQ_LAST)
611 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
613 ret = btrfs_search_old_slot(root, &search_key, path, time_seq);
616 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
617 ref->root_id, level, ref->count, ret,
618 ref->key_for_search.objectid, ref->key_for_search.type,
619 ref->key_for_search.offset);
623 eb = path->nodes[level];
625 if (WARN_ON(!level)) {
630 eb = path->nodes[level];
633 ret = add_all_parents(root, path, parents, preftrees, ref, level,
634 time_seq, extent_item_pos, ignore_offset);
636 btrfs_put_root(root);
638 path->lowest_level = 0;
639 btrfs_release_path(path);
643 static struct extent_inode_elem *
644 unode_aux_to_inode_list(struct ulist_node *node)
648 return (struct extent_inode_elem *)(uintptr_t)node->aux;
652 * We maintain three separate rbtrees: one for direct refs, one for
653 * indirect refs which have a key, and one for indirect refs which do not
654 * have a key. Each tree does merge on insertion.
656 * Once all of the references are located, we iterate over the tree of
657 * indirect refs with missing keys. An appropriate key is located and
658 * the ref is moved onto the tree for indirect refs. After all missing
659 * keys are thus located, we iterate over the indirect ref tree, resolve
660 * each reference, and then insert the resolved reference onto the
661 * direct tree (merging there too).
663 * New backrefs (i.e., for parent nodes) are added to the appropriate
664 * rbtree as they are encountered. The new backrefs are subsequently
667 static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
668 struct btrfs_path *path, u64 time_seq,
669 struct preftrees *preftrees,
670 const u64 *extent_item_pos,
671 struct share_check *sc, bool ignore_offset)
675 struct ulist *parents;
676 struct ulist_node *node;
677 struct ulist_iterator uiter;
678 struct rb_node *rnode;
680 parents = ulist_alloc(GFP_NOFS);
685 * We could trade memory usage for performance here by iterating
686 * the tree, allocating new refs for each insertion, and then
687 * freeing the entire indirect tree when we're done. In some test
688 * cases, the tree can grow quite large (~200k objects).
690 while ((rnode = rb_first_cached(&preftrees->indirect.root))) {
691 struct prelim_ref *ref;
693 ref = rb_entry(rnode, struct prelim_ref, rbnode);
694 if (WARN(ref->parent,
695 "BUG: direct ref found in indirect tree")) {
700 rb_erase_cached(&ref->rbnode, &preftrees->indirect.root);
701 preftrees->indirect.count--;
703 if (ref->count == 0) {
708 if (sc && sc->root_objectid &&
709 ref->root_id != sc->root_objectid) {
711 ret = BACKREF_FOUND_SHARED;
714 err = resolve_indirect_ref(fs_info, path, time_seq, preftrees,
715 ref, parents, extent_item_pos,
718 * we can only tolerate ENOENT,otherwise,we should catch error
719 * and return directly.
721 if (err == -ENOENT) {
722 prelim_ref_insert(fs_info, &preftrees->direct, ref,
731 /* we put the first parent into the ref at hand */
732 ULIST_ITER_INIT(&uiter);
733 node = ulist_next(parents, &uiter);
734 ref->parent = node ? node->val : 0;
735 ref->inode_list = unode_aux_to_inode_list(node);
737 /* Add a prelim_ref(s) for any other parent(s). */
738 while ((node = ulist_next(parents, &uiter))) {
739 struct prelim_ref *new_ref;
741 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
748 memcpy(new_ref, ref, sizeof(*ref));
749 new_ref->parent = node->val;
750 new_ref->inode_list = unode_aux_to_inode_list(node);
751 prelim_ref_insert(fs_info, &preftrees->direct,
756 * Now it's a direct ref, put it in the direct tree. We must
757 * do this last because the ref could be merged/freed here.
759 prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL);
761 ulist_reinit(parents);
770 * read tree blocks and add keys where required.
772 static int add_missing_keys(struct btrfs_fs_info *fs_info,
773 struct preftrees *preftrees, bool lock)
775 struct prelim_ref *ref;
776 struct extent_buffer *eb;
777 struct preftree *tree = &preftrees->indirect_missing_keys;
778 struct rb_node *node;
780 while ((node = rb_first_cached(&tree->root))) {
781 ref = rb_entry(node, struct prelim_ref, rbnode);
782 rb_erase_cached(node, &tree->root);
784 BUG_ON(ref->parent); /* should not be a direct ref */
785 BUG_ON(ref->key_for_search.type);
786 BUG_ON(!ref->wanted_disk_byte);
788 eb = read_tree_block(fs_info, ref->wanted_disk_byte,
789 ref->root_id, 0, ref->level - 1, NULL);
794 if (!extent_buffer_uptodate(eb)) {
796 free_extent_buffer(eb);
801 btrfs_tree_read_lock(eb);
802 if (btrfs_header_level(eb) == 0)
803 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
805 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
807 btrfs_tree_read_unlock(eb);
808 free_extent_buffer(eb);
809 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
816 * add all currently queued delayed refs from this head whose seq nr is
817 * smaller or equal that seq to the list
819 static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
820 struct btrfs_delayed_ref_head *head, u64 seq,
821 struct preftrees *preftrees, struct share_check *sc)
823 struct btrfs_delayed_ref_node *node;
824 struct btrfs_key key;
829 spin_lock(&head->lock);
830 for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
831 node = rb_entry(n, struct btrfs_delayed_ref_node,
836 switch (node->action) {
837 case BTRFS_ADD_DELAYED_EXTENT:
838 case BTRFS_UPDATE_DELAYED_HEAD:
841 case BTRFS_ADD_DELAYED_REF:
842 count = node->ref_mod;
844 case BTRFS_DROP_DELAYED_REF:
845 count = node->ref_mod * -1;
850 switch (node->type) {
851 case BTRFS_TREE_BLOCK_REF_KEY: {
852 /* NORMAL INDIRECT METADATA backref */
853 struct btrfs_delayed_tree_ref *ref;
854 struct btrfs_key *key_ptr = NULL;
856 if (head->extent_op && head->extent_op->update_key) {
857 btrfs_disk_key_to_cpu(&key, &head->extent_op->key);
861 ref = btrfs_delayed_node_to_tree_ref(node);
862 ret = add_indirect_ref(fs_info, preftrees, ref->root,
863 key_ptr, ref->level + 1,
864 node->bytenr, count, sc,
868 case BTRFS_SHARED_BLOCK_REF_KEY: {
869 /* SHARED DIRECT METADATA backref */
870 struct btrfs_delayed_tree_ref *ref;
872 ref = btrfs_delayed_node_to_tree_ref(node);
874 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
875 ref->parent, node->bytenr, count,
879 case BTRFS_EXTENT_DATA_REF_KEY: {
880 /* NORMAL INDIRECT DATA backref */
881 struct btrfs_delayed_data_ref *ref;
882 ref = btrfs_delayed_node_to_data_ref(node);
884 key.objectid = ref->objectid;
885 key.type = BTRFS_EXTENT_DATA_KEY;
886 key.offset = ref->offset;
889 * If we have a share check context and a reference for
890 * another inode, we can't exit immediately. This is
891 * because even if this is a BTRFS_ADD_DELAYED_REF
892 * reference we may find next a BTRFS_DROP_DELAYED_REF
893 * which cancels out this ADD reference.
895 * If this is a DROP reference and there was no previous
896 * ADD reference, then we need to signal that when we
897 * process references from the extent tree (through
898 * add_inline_refs() and add_keyed_refs()), we should
899 * not exit early if we find a reference for another
900 * inode, because one of the delayed DROP references
901 * may cancel that reference in the extent tree.
904 sc->have_delayed_delete_refs = true;
906 ret = add_indirect_ref(fs_info, preftrees, ref->root,
907 &key, 0, node->bytenr, count, sc,
911 case BTRFS_SHARED_DATA_REF_KEY: {
912 /* SHARED DIRECT FULL backref */
913 struct btrfs_delayed_data_ref *ref;
915 ref = btrfs_delayed_node_to_data_ref(node);
917 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
918 node->bytenr, count, sc,
926 * We must ignore BACKREF_FOUND_SHARED until all delayed
927 * refs have been checked.
929 if (ret && (ret != BACKREF_FOUND_SHARED))
933 ret = extent_is_shared(sc);
935 spin_unlock(&head->lock);
940 * add all inline backrefs for bytenr to the list
942 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
944 static int add_inline_refs(const struct btrfs_fs_info *fs_info,
945 struct btrfs_path *path, u64 bytenr,
946 int *info_level, struct preftrees *preftrees,
947 struct share_check *sc)
951 struct extent_buffer *leaf;
952 struct btrfs_key key;
953 struct btrfs_key found_key;
956 struct btrfs_extent_item *ei;
961 * enumerate all inline refs
963 leaf = path->nodes[0];
964 slot = path->slots[0];
966 item_size = btrfs_item_size(leaf, slot);
967 BUG_ON(item_size < sizeof(*ei));
969 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
970 flags = btrfs_extent_flags(leaf, ei);
971 btrfs_item_key_to_cpu(leaf, &found_key, slot);
973 ptr = (unsigned long)(ei + 1);
974 end = (unsigned long)ei + item_size;
976 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
977 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
978 struct btrfs_tree_block_info *info;
980 info = (struct btrfs_tree_block_info *)ptr;
981 *info_level = btrfs_tree_block_level(leaf, info);
982 ptr += sizeof(struct btrfs_tree_block_info);
984 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
985 *info_level = found_key.offset;
987 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
991 struct btrfs_extent_inline_ref *iref;
995 iref = (struct btrfs_extent_inline_ref *)ptr;
996 type = btrfs_get_extent_inline_ref_type(leaf, iref,
998 if (type == BTRFS_REF_TYPE_INVALID)
1001 offset = btrfs_extent_inline_ref_offset(leaf, iref);
1004 case BTRFS_SHARED_BLOCK_REF_KEY:
1005 ret = add_direct_ref(fs_info, preftrees,
1006 *info_level + 1, offset,
1007 bytenr, 1, NULL, GFP_NOFS);
1009 case BTRFS_SHARED_DATA_REF_KEY: {
1010 struct btrfs_shared_data_ref *sdref;
1013 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
1014 count = btrfs_shared_data_ref_count(leaf, sdref);
1016 ret = add_direct_ref(fs_info, preftrees, 0, offset,
1017 bytenr, count, sc, GFP_NOFS);
1020 case BTRFS_TREE_BLOCK_REF_KEY:
1021 ret = add_indirect_ref(fs_info, preftrees, offset,
1022 NULL, *info_level + 1,
1023 bytenr, 1, NULL, GFP_NOFS);
1025 case BTRFS_EXTENT_DATA_REF_KEY: {
1026 struct btrfs_extent_data_ref *dref;
1030 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1031 count = btrfs_extent_data_ref_count(leaf, dref);
1032 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1034 key.type = BTRFS_EXTENT_DATA_KEY;
1035 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1037 if (sc && sc->inum && key.objectid != sc->inum &&
1038 !sc->have_delayed_delete_refs) {
1039 ret = BACKREF_FOUND_SHARED;
1043 root = btrfs_extent_data_ref_root(leaf, dref);
1045 ret = add_indirect_ref(fs_info, preftrees, root,
1046 &key, 0, bytenr, count,
1056 ptr += btrfs_extent_inline_ref_size(type);
1063 * add all non-inline backrefs for bytenr to the list
1065 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
1067 static int add_keyed_refs(struct btrfs_root *extent_root,
1068 struct btrfs_path *path, u64 bytenr,
1069 int info_level, struct preftrees *preftrees,
1070 struct share_check *sc)
1072 struct btrfs_fs_info *fs_info = extent_root->fs_info;
1075 struct extent_buffer *leaf;
1076 struct btrfs_key key;
1079 ret = btrfs_next_item(extent_root, path);
1087 slot = path->slots[0];
1088 leaf = path->nodes[0];
1089 btrfs_item_key_to_cpu(leaf, &key, slot);
1091 if (key.objectid != bytenr)
1093 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1095 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1099 case BTRFS_SHARED_BLOCK_REF_KEY:
1100 /* SHARED DIRECT METADATA backref */
1101 ret = add_direct_ref(fs_info, preftrees,
1102 info_level + 1, key.offset,
1103 bytenr, 1, NULL, GFP_NOFS);
1105 case BTRFS_SHARED_DATA_REF_KEY: {
1106 /* SHARED DIRECT FULL backref */
1107 struct btrfs_shared_data_ref *sdref;
1110 sdref = btrfs_item_ptr(leaf, slot,
1111 struct btrfs_shared_data_ref);
1112 count = btrfs_shared_data_ref_count(leaf, sdref);
1113 ret = add_direct_ref(fs_info, preftrees, 0,
1114 key.offset, bytenr, count,
1118 case BTRFS_TREE_BLOCK_REF_KEY:
1119 /* NORMAL INDIRECT METADATA backref */
1120 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1121 NULL, info_level + 1, bytenr,
1124 case BTRFS_EXTENT_DATA_REF_KEY: {
1125 /* NORMAL INDIRECT DATA backref */
1126 struct btrfs_extent_data_ref *dref;
1130 dref = btrfs_item_ptr(leaf, slot,
1131 struct btrfs_extent_data_ref);
1132 count = btrfs_extent_data_ref_count(leaf, dref);
1133 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1135 key.type = BTRFS_EXTENT_DATA_KEY;
1136 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1138 if (sc && sc->inum && key.objectid != sc->inum &&
1139 !sc->have_delayed_delete_refs) {
1140 ret = BACKREF_FOUND_SHARED;
1144 root = btrfs_extent_data_ref_root(leaf, dref);
1145 ret = add_indirect_ref(fs_info, preftrees, root,
1146 &key, 0, bytenr, count,
1162 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1163 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1164 * indirect refs to their parent bytenr.
1165 * When roots are found, they're added to the roots list
1167 * If time_seq is set to BTRFS_SEQ_LAST, it will not search delayed_refs, and
1168 * behave much like trans == NULL case, the difference only lies in it will not
1170 * The special case is for qgroup to search roots in commit_transaction().
1172 * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a
1173 * shared extent is detected.
1175 * Otherwise this returns 0 for success and <0 for an error.
1177 * If ignore_offset is set to false, only extent refs whose offsets match
1178 * extent_item_pos are returned. If true, every extent ref is returned
1179 * and extent_item_pos is ignored.
1181 * FIXME some caching might speed things up
1183 static int find_parent_nodes(struct btrfs_trans_handle *trans,
1184 struct btrfs_fs_info *fs_info, u64 bytenr,
1185 u64 time_seq, struct ulist *refs,
1186 struct ulist *roots, const u64 *extent_item_pos,
1187 struct share_check *sc, bool ignore_offset)
1189 struct btrfs_root *root = btrfs_extent_root(fs_info, bytenr);
1190 struct btrfs_key key;
1191 struct btrfs_path *path;
1192 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1193 struct btrfs_delayed_ref_head *head;
1196 struct prelim_ref *ref;
1197 struct rb_node *node;
1198 struct extent_inode_elem *eie = NULL;
1199 struct preftrees preftrees = {
1200 .direct = PREFTREE_INIT,
1201 .indirect = PREFTREE_INIT,
1202 .indirect_missing_keys = PREFTREE_INIT
1205 key.objectid = bytenr;
1206 key.offset = (u64)-1;
1207 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1208 key.type = BTRFS_METADATA_ITEM_KEY;
1210 key.type = BTRFS_EXTENT_ITEM_KEY;
1212 path = btrfs_alloc_path();
1216 path->search_commit_root = 1;
1217 path->skip_locking = 1;
1220 if (time_seq == BTRFS_SEQ_LAST)
1221 path->skip_locking = 1;
1226 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1230 /* This shouldn't happen, indicates a bug or fs corruption. */
1236 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1237 time_seq != BTRFS_SEQ_LAST) {
1239 * We have a specific time_seq we care about and trans which
1240 * means we have the path lock, we need to grab the ref head and
1241 * lock it so we have a consistent view of the refs at the given
1244 delayed_refs = &trans->transaction->delayed_refs;
1245 spin_lock(&delayed_refs->lock);
1246 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
1248 if (!mutex_trylock(&head->mutex)) {
1249 refcount_inc(&head->refs);
1250 spin_unlock(&delayed_refs->lock);
1252 btrfs_release_path(path);
1255 * Mutex was contended, block until it's
1256 * released and try again
1258 mutex_lock(&head->mutex);
1259 mutex_unlock(&head->mutex);
1260 btrfs_put_delayed_ref_head(head);
1263 spin_unlock(&delayed_refs->lock);
1264 ret = add_delayed_refs(fs_info, head, time_seq,
1266 mutex_unlock(&head->mutex);
1270 spin_unlock(&delayed_refs->lock);
1274 if (path->slots[0]) {
1275 struct extent_buffer *leaf;
1279 leaf = path->nodes[0];
1280 slot = path->slots[0];
1281 btrfs_item_key_to_cpu(leaf, &key, slot);
1282 if (key.objectid == bytenr &&
1283 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1284 key.type == BTRFS_METADATA_ITEM_KEY)) {
1285 ret = add_inline_refs(fs_info, path, bytenr,
1286 &info_level, &preftrees, sc);
1289 ret = add_keyed_refs(root, path, bytenr, info_level,
1296 btrfs_release_path(path);
1298 ret = add_missing_keys(fs_info, &preftrees, path->skip_locking == 0);
1302 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root));
1304 ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees,
1305 extent_item_pos, sc, ignore_offset);
1309 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root));
1312 * This walks the tree of merged and resolved refs. Tree blocks are
1313 * read in as needed. Unique entries are added to the ulist, and
1314 * the list of found roots is updated.
1316 * We release the entire tree in one go before returning.
1318 node = rb_first_cached(&preftrees.direct.root);
1320 ref = rb_entry(node, struct prelim_ref, rbnode);
1321 node = rb_next(&ref->rbnode);
1323 * ref->count < 0 can happen here if there are delayed
1324 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1325 * prelim_ref_insert() relies on this when merging
1326 * identical refs to keep the overall count correct.
1327 * prelim_ref_insert() will merge only those refs
1328 * which compare identically. Any refs having
1329 * e.g. different offsets would not be merged,
1330 * and would retain their original ref->count < 0.
1332 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1333 if (sc && sc->root_objectid &&
1334 ref->root_id != sc->root_objectid) {
1335 ret = BACKREF_FOUND_SHARED;
1339 /* no parent == root of tree */
1340 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1344 if (ref->count && ref->parent) {
1345 if (extent_item_pos && !ref->inode_list &&
1347 struct extent_buffer *eb;
1349 eb = read_tree_block(fs_info, ref->parent, 0,
1350 0, ref->level, NULL);
1355 if (!extent_buffer_uptodate(eb)) {
1356 free_extent_buffer(eb);
1361 if (!path->skip_locking)
1362 btrfs_tree_read_lock(eb);
1363 ret = find_extent_in_eb(eb, bytenr,
1364 *extent_item_pos, &eie, ignore_offset);
1365 if (!path->skip_locking)
1366 btrfs_tree_read_unlock(eb);
1367 free_extent_buffer(eb);
1370 ref->inode_list = eie;
1372 ret = ulist_add_merge_ptr(refs, ref->parent,
1374 (void **)&eie, GFP_NOFS);
1377 if (!ret && extent_item_pos) {
1379 * We've recorded that parent, so we must extend
1380 * its inode list here.
1382 * However if there was corruption we may not
1383 * have found an eie, return an error in this
1393 eie->next = ref->inode_list;
1401 btrfs_free_path(path);
1403 prelim_release(&preftrees.direct);
1404 prelim_release(&preftrees.indirect);
1405 prelim_release(&preftrees.indirect_missing_keys);
1408 free_inode_elem_list(eie);
1412 static void free_leaf_list(struct ulist *blocks)
1414 struct ulist_node *node = NULL;
1415 struct extent_inode_elem *eie;
1416 struct ulist_iterator uiter;
1418 ULIST_ITER_INIT(&uiter);
1419 while ((node = ulist_next(blocks, &uiter))) {
1422 eie = unode_aux_to_inode_list(node);
1423 free_inode_elem_list(eie);
1431 * Finds all leafs with a reference to the specified combination of bytenr and
1432 * offset. key_list_head will point to a list of corresponding keys (caller must
1433 * free each list element). The leafs will be stored in the leafs ulist, which
1434 * must be freed with ulist_free.
1436 * returns 0 on success, <0 on error
1438 int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1439 struct btrfs_fs_info *fs_info, u64 bytenr,
1440 u64 time_seq, struct ulist **leafs,
1441 const u64 *extent_item_pos, bool ignore_offset)
1445 *leafs = ulist_alloc(GFP_NOFS);
1449 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1450 *leafs, NULL, extent_item_pos, NULL, ignore_offset);
1451 if (ret < 0 && ret != -ENOENT) {
1452 free_leaf_list(*leafs);
1460 * walk all backrefs for a given extent to find all roots that reference this
1461 * extent. Walking a backref means finding all extents that reference this
1462 * extent and in turn walk the backrefs of those, too. Naturally this is a
1463 * recursive process, but here it is implemented in an iterative fashion: We
1464 * find all referencing extents for the extent in question and put them on a
1465 * list. In turn, we find all referencing extents for those, further appending
1466 * to the list. The way we iterate the list allows adding more elements after
1467 * the current while iterating. The process stops when we reach the end of the
1468 * list. Found roots are added to the roots list.
1470 * returns 0 on success, < 0 on error.
1472 static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
1473 struct btrfs_fs_info *fs_info, u64 bytenr,
1474 u64 time_seq, struct ulist **roots,
1478 struct ulist_node *node = NULL;
1479 struct ulist_iterator uiter;
1482 tmp = ulist_alloc(GFP_NOFS);
1485 *roots = ulist_alloc(GFP_NOFS);
1491 ULIST_ITER_INIT(&uiter);
1493 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1494 tmp, *roots, NULL, NULL, ignore_offset);
1495 if (ret < 0 && ret != -ENOENT) {
1501 node = ulist_next(tmp, &uiter);
1512 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1513 struct btrfs_fs_info *fs_info, u64 bytenr,
1514 u64 time_seq, struct ulist **roots,
1515 bool skip_commit_root_sem)
1519 if (!trans && !skip_commit_root_sem)
1520 down_read(&fs_info->commit_root_sem);
1521 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr,
1522 time_seq, roots, false);
1523 if (!trans && !skip_commit_root_sem)
1524 up_read(&fs_info->commit_root_sem);
1529 * The caller has joined a transaction or is holding a read lock on the
1530 * fs_info->commit_root_sem semaphore, so no need to worry about the root's last
1531 * snapshot field changing while updating or checking the cache.
1533 static bool lookup_backref_shared_cache(struct btrfs_backref_shared_cache *cache,
1534 struct btrfs_root *root,
1535 u64 bytenr, int level, bool *is_shared)
1537 struct btrfs_backref_shared_cache_entry *entry;
1539 if (!cache->use_cache)
1542 if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL))
1546 * Level -1 is used for the data extent, which is not reliable to cache
1547 * because its reference count can increase or decrease without us
1548 * realizing. We cache results only for extent buffers that lead from
1549 * the root node down to the leaf with the file extent item.
1553 entry = &cache->entries[level];
1555 /* Unused cache entry or being used for some other extent buffer. */
1556 if (entry->bytenr != bytenr)
1560 * We cached a false result, but the last snapshot generation of the
1561 * root changed, so we now have a snapshot. Don't trust the result.
1563 if (!entry->is_shared &&
1564 entry->gen != btrfs_root_last_snapshot(&root->root_item))
1568 * If we cached a true result and the last generation used for dropping
1569 * a root changed, we can not trust the result, because the dropped root
1570 * could be a snapshot sharing this extent buffer.
1572 if (entry->is_shared &&
1573 entry->gen != btrfs_get_last_root_drop_gen(root->fs_info))
1576 *is_shared = entry->is_shared;
1578 * If the node at this level is shared, than all nodes below are also
1579 * shared. Currently some of the nodes below may be marked as not shared
1580 * because we have just switched from one leaf to another, and switched
1581 * also other nodes above the leaf and below the current level, so mark
1585 for (int i = 0; i < level; i++) {
1586 cache->entries[i].is_shared = true;
1587 cache->entries[i].gen = entry->gen;
1595 * The caller has joined a transaction or is holding a read lock on the
1596 * fs_info->commit_root_sem semaphore, so no need to worry about the root's last
1597 * snapshot field changing while updating or checking the cache.
1599 static void store_backref_shared_cache(struct btrfs_backref_shared_cache *cache,
1600 struct btrfs_root *root,
1601 u64 bytenr, int level, bool is_shared)
1603 struct btrfs_backref_shared_cache_entry *entry;
1606 if (!cache->use_cache)
1609 if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL))
1613 * Level -1 is used for the data extent, which is not reliable to cache
1614 * because its reference count can increase or decrease without us
1615 * realizing. We cache results only for extent buffers that lead from
1616 * the root node down to the leaf with the file extent item.
1621 gen = btrfs_get_last_root_drop_gen(root->fs_info);
1623 gen = btrfs_root_last_snapshot(&root->root_item);
1625 entry = &cache->entries[level];
1626 entry->bytenr = bytenr;
1627 entry->is_shared = is_shared;
1631 * If we found an extent buffer is shared, set the cache result for all
1632 * extent buffers below it to true. As nodes in the path are COWed,
1633 * their sharedness is moved to their children, and if a leaf is COWed,
1634 * then the sharedness of a data extent becomes direct, the refcount of
1635 * data extent is increased in the extent item at the extent tree.
1638 for (int i = 0; i < level; i++) {
1639 entry = &cache->entries[i];
1640 entry->is_shared = is_shared;
1647 * Check if a data extent is shared or not.
1649 * @root: The root the inode belongs to.
1650 * @inum: Number of the inode whose extent we are checking.
1651 * @bytenr: Logical bytenr of the extent we are checking.
1652 * @extent_gen: Generation of the extent (file extent item) or 0 if it is
1654 * @roots: List of roots this extent is shared among.
1655 * @tmp: Temporary list used for iteration.
1656 * @cache: A backref lookup result cache.
1658 * btrfs_is_data_extent_shared uses the backref walking code but will short
1659 * circuit as soon as it finds a root or inode that doesn't match the
1660 * one passed in. This provides a significant performance benefit for
1661 * callers (such as fiemap) which want to know whether the extent is
1662 * shared but do not need a ref count.
1664 * This attempts to attach to the running transaction in order to account for
1665 * delayed refs, but continues on even when no running transaction exists.
1667 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1669 int btrfs_is_data_extent_shared(struct btrfs_root *root, u64 inum, u64 bytenr,
1671 struct ulist *roots, struct ulist *tmp,
1672 struct btrfs_backref_shared_cache *cache)
1674 struct btrfs_fs_info *fs_info = root->fs_info;
1675 struct btrfs_trans_handle *trans;
1676 struct ulist_iterator uiter;
1677 struct ulist_node *node;
1678 struct btrfs_seq_list elem = BTRFS_SEQ_LIST_INIT(elem);
1680 struct share_check shared = {
1681 .root_objectid = root->root_key.objectid,
1684 .have_delayed_delete_refs = false,
1691 trans = btrfs_join_transaction_nostart(root);
1692 if (IS_ERR(trans)) {
1693 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
1694 ret = PTR_ERR(trans);
1698 down_read(&fs_info->commit_root_sem);
1700 btrfs_get_tree_mod_seq(fs_info, &elem);
1703 /* -1 means we are in the bytenr of the data extent. */
1705 ULIST_ITER_INIT(&uiter);
1706 cache->use_cache = true;
1711 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1712 roots, NULL, &shared, false);
1713 if (ret == BACKREF_FOUND_SHARED) {
1714 /* this is the only condition under which we return 1 */
1717 store_backref_shared_cache(cache, root, bytenr,
1721 if (ret < 0 && ret != -ENOENT)
1725 * If our data extent is not shared through reflinks and it was
1726 * created in a generation after the last one used to create a
1727 * snapshot of the inode's root, then it can not be shared
1728 * indirectly through subtrees, as that can only happen with
1729 * snapshots. In this case bail out, no need to check for the
1730 * sharedness of extent buffers.
1733 extent_gen > btrfs_root_last_snapshot(&root->root_item))
1737 * If our data extent was not directly shared (without multiple
1738 * reference items), than it might have a single reference item
1739 * with a count > 1 for the same offset, which means there are 2
1740 * (or more) file extent items that point to the data extent -
1741 * this happens when a file extent item needs to be split and
1742 * then one item gets moved to another leaf due to a b+tree leaf
1743 * split when inserting some item. In this case the file extent
1744 * items may be located in different leaves and therefore some
1745 * of the leaves may be referenced through shared subtrees while
1746 * others are not. Since our extent buffer cache only works for
1747 * a single path (by far the most common case and simpler to
1748 * deal with), we can not use it if we have multiple leaves
1749 * (which implies multiple paths).
1751 if (level == -1 && tmp->nnodes > 1)
1752 cache->use_cache = false;
1755 store_backref_shared_cache(cache, root, bytenr,
1757 node = ulist_next(tmp, &uiter);
1762 cached = lookup_backref_shared_cache(cache, root, bytenr, level,
1765 ret = (is_shared ? 1 : 0);
1768 shared.share_count = 0;
1769 shared.have_delayed_delete_refs = false;
1774 btrfs_put_tree_mod_seq(fs_info, &elem);
1775 btrfs_end_transaction(trans);
1777 up_read(&fs_info->commit_root_sem);
1780 ulist_release(roots);
1785 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1786 u64 start_off, struct btrfs_path *path,
1787 struct btrfs_inode_extref **ret_extref,
1791 struct btrfs_key key;
1792 struct btrfs_key found_key;
1793 struct btrfs_inode_extref *extref;
1794 const struct extent_buffer *leaf;
1797 key.objectid = inode_objectid;
1798 key.type = BTRFS_INODE_EXTREF_KEY;
1799 key.offset = start_off;
1801 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1806 leaf = path->nodes[0];
1807 slot = path->slots[0];
1808 if (slot >= btrfs_header_nritems(leaf)) {
1810 * If the item at offset is not found,
1811 * btrfs_search_slot will point us to the slot
1812 * where it should be inserted. In our case
1813 * that will be the slot directly before the
1814 * next INODE_REF_KEY_V2 item. In the case
1815 * that we're pointing to the last slot in a
1816 * leaf, we must move one leaf over.
1818 ret = btrfs_next_leaf(root, path);
1827 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1830 * Check that we're still looking at an extended ref key for
1831 * this particular objectid. If we have different
1832 * objectid or type then there are no more to be found
1833 * in the tree and we can exit.
1836 if (found_key.objectid != inode_objectid)
1838 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1842 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1843 extref = (struct btrfs_inode_extref *)ptr;
1844 *ret_extref = extref;
1846 *found_off = found_key.offset;
1854 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1855 * Elements of the path are separated by '/' and the path is guaranteed to be
1856 * 0-terminated. the path is only given within the current file system.
1857 * Therefore, it never starts with a '/'. the caller is responsible to provide
1858 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1859 * the start point of the resulting string is returned. this pointer is within
1861 * in case the path buffer would overflow, the pointer is decremented further
1862 * as if output was written to the buffer, though no more output is actually
1863 * generated. that way, the caller can determine how much space would be
1864 * required for the path to fit into the buffer. in that case, the returned
1865 * value will be smaller than dest. callers must check this!
1867 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1868 u32 name_len, unsigned long name_off,
1869 struct extent_buffer *eb_in, u64 parent,
1870 char *dest, u32 size)
1875 s64 bytes_left = ((s64)size) - 1;
1876 struct extent_buffer *eb = eb_in;
1877 struct btrfs_key found_key;
1878 struct btrfs_inode_ref *iref;
1880 if (bytes_left >= 0)
1881 dest[bytes_left] = '\0';
1884 bytes_left -= name_len;
1885 if (bytes_left >= 0)
1886 read_extent_buffer(eb, dest + bytes_left,
1887 name_off, name_len);
1889 if (!path->skip_locking)
1890 btrfs_tree_read_unlock(eb);
1891 free_extent_buffer(eb);
1893 ret = btrfs_find_item(fs_root, path, parent, 0,
1894 BTRFS_INODE_REF_KEY, &found_key);
1900 next_inum = found_key.offset;
1902 /* regular exit ahead */
1903 if (parent == next_inum)
1906 slot = path->slots[0];
1907 eb = path->nodes[0];
1908 /* make sure we can use eb after releasing the path */
1910 path->nodes[0] = NULL;
1913 btrfs_release_path(path);
1914 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1916 name_len = btrfs_inode_ref_name_len(eb, iref);
1917 name_off = (unsigned long)(iref + 1);
1921 if (bytes_left >= 0)
1922 dest[bytes_left] = '/';
1925 btrfs_release_path(path);
1928 return ERR_PTR(ret);
1930 return dest + bytes_left;
1934 * this makes the path point to (logical EXTENT_ITEM *)
1935 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1936 * tree blocks and <0 on error.
1938 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1939 struct btrfs_path *path, struct btrfs_key *found_key,
1942 struct btrfs_root *extent_root = btrfs_extent_root(fs_info, logical);
1947 const struct extent_buffer *eb;
1948 struct btrfs_extent_item *ei;
1949 struct btrfs_key key;
1951 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1952 key.type = BTRFS_METADATA_ITEM_KEY;
1954 key.type = BTRFS_EXTENT_ITEM_KEY;
1955 key.objectid = logical;
1956 key.offset = (u64)-1;
1958 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
1962 ret = btrfs_previous_extent_item(extent_root, path, 0);
1968 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1969 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1970 size = fs_info->nodesize;
1971 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1972 size = found_key->offset;
1974 if (found_key->objectid > logical ||
1975 found_key->objectid + size <= logical) {
1976 btrfs_debug(fs_info,
1977 "logical %llu is not within any extent", logical);
1981 eb = path->nodes[0];
1982 item_size = btrfs_item_size(eb, path->slots[0]);
1983 BUG_ON(item_size < sizeof(*ei));
1985 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1986 flags = btrfs_extent_flags(eb, ei);
1988 btrfs_debug(fs_info,
1989 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1990 logical, logical - found_key->objectid, found_key->objectid,
1991 found_key->offset, flags, item_size);
1993 WARN_ON(!flags_ret);
1995 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1996 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1997 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1998 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
2008 * helper function to iterate extent inline refs. ptr must point to a 0 value
2009 * for the first call and may be modified. it is used to track state.
2010 * if more refs exist, 0 is returned and the next call to
2011 * get_extent_inline_ref must pass the modified ptr parameter to get the
2012 * next ref. after the last ref was processed, 1 is returned.
2013 * returns <0 on error
2015 static int get_extent_inline_ref(unsigned long *ptr,
2016 const struct extent_buffer *eb,
2017 const struct btrfs_key *key,
2018 const struct btrfs_extent_item *ei,
2020 struct btrfs_extent_inline_ref **out_eiref,
2025 struct btrfs_tree_block_info *info;
2029 flags = btrfs_extent_flags(eb, ei);
2030 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2031 if (key->type == BTRFS_METADATA_ITEM_KEY) {
2032 /* a skinny metadata extent */
2034 (struct btrfs_extent_inline_ref *)(ei + 1);
2036 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
2037 info = (struct btrfs_tree_block_info *)(ei + 1);
2039 (struct btrfs_extent_inline_ref *)(info + 1);
2042 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
2044 *ptr = (unsigned long)*out_eiref;
2045 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
2049 end = (unsigned long)ei + item_size;
2050 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
2051 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
2052 BTRFS_REF_TYPE_ANY);
2053 if (*out_type == BTRFS_REF_TYPE_INVALID)
2056 *ptr += btrfs_extent_inline_ref_size(*out_type);
2057 WARN_ON(*ptr > end);
2059 return 1; /* last */
2065 * reads the tree block backref for an extent. tree level and root are returned
2066 * through out_level and out_root. ptr must point to a 0 value for the first
2067 * call and may be modified (see get_extent_inline_ref comment).
2068 * returns 0 if data was provided, 1 if there was no more data to provide or
2071 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
2072 struct btrfs_key *key, struct btrfs_extent_item *ei,
2073 u32 item_size, u64 *out_root, u8 *out_level)
2077 struct btrfs_extent_inline_ref *eiref;
2079 if (*ptr == (unsigned long)-1)
2083 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
2088 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
2089 type == BTRFS_SHARED_BLOCK_REF_KEY)
2096 /* we can treat both ref types equally here */
2097 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
2099 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
2100 struct btrfs_tree_block_info *info;
2102 info = (struct btrfs_tree_block_info *)(ei + 1);
2103 *out_level = btrfs_tree_block_level(eb, info);
2105 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
2106 *out_level = (u8)key->offset;
2110 *ptr = (unsigned long)-1;
2115 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
2116 struct extent_inode_elem *inode_list,
2117 u64 root, u64 extent_item_objectid,
2118 iterate_extent_inodes_t *iterate, void *ctx)
2120 struct extent_inode_elem *eie;
2123 for (eie = inode_list; eie; eie = eie->next) {
2124 btrfs_debug(fs_info,
2125 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
2126 extent_item_objectid, eie->inum,
2128 ret = iterate(eie->inum, eie->offset, root, ctx);
2130 btrfs_debug(fs_info,
2131 "stopping iteration for %llu due to ret=%d",
2132 extent_item_objectid, ret);
2141 * calls iterate() for every inode that references the extent identified by
2142 * the given parameters.
2143 * when the iterator function returns a non-zero value, iteration stops.
2145 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
2146 u64 extent_item_objectid, u64 extent_item_pos,
2147 int search_commit_root,
2148 iterate_extent_inodes_t *iterate, void *ctx,
2152 struct btrfs_trans_handle *trans = NULL;
2153 struct ulist *refs = NULL;
2154 struct ulist *roots = NULL;
2155 struct ulist_node *ref_node = NULL;
2156 struct ulist_node *root_node = NULL;
2157 struct btrfs_seq_list seq_elem = BTRFS_SEQ_LIST_INIT(seq_elem);
2158 struct ulist_iterator ref_uiter;
2159 struct ulist_iterator root_uiter;
2161 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
2162 extent_item_objectid);
2164 if (!search_commit_root) {
2165 trans = btrfs_attach_transaction(fs_info->tree_root);
2166 if (IS_ERR(trans)) {
2167 if (PTR_ERR(trans) != -ENOENT &&
2168 PTR_ERR(trans) != -EROFS)
2169 return PTR_ERR(trans);
2175 btrfs_get_tree_mod_seq(fs_info, &seq_elem);
2177 down_read(&fs_info->commit_root_sem);
2179 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
2180 seq_elem.seq, &refs,
2181 &extent_item_pos, ignore_offset);
2185 ULIST_ITER_INIT(&ref_uiter);
2186 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
2187 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val,
2188 seq_elem.seq, &roots,
2192 ULIST_ITER_INIT(&root_uiter);
2193 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
2194 btrfs_debug(fs_info,
2195 "root %llu references leaf %llu, data list %#llx",
2196 root_node->val, ref_node->val,
2198 ret = iterate_leaf_refs(fs_info,
2199 (struct extent_inode_elem *)
2200 (uintptr_t)ref_node->aux,
2202 extent_item_objectid,
2208 free_leaf_list(refs);
2211 btrfs_put_tree_mod_seq(fs_info, &seq_elem);
2212 btrfs_end_transaction(trans);
2214 up_read(&fs_info->commit_root_sem);
2220 static int build_ino_list(u64 inum, u64 offset, u64 root, void *ctx)
2222 struct btrfs_data_container *inodes = ctx;
2223 const size_t c = 3 * sizeof(u64);
2225 if (inodes->bytes_left >= c) {
2226 inodes->bytes_left -= c;
2227 inodes->val[inodes->elem_cnt] = inum;
2228 inodes->val[inodes->elem_cnt + 1] = offset;
2229 inodes->val[inodes->elem_cnt + 2] = root;
2230 inodes->elem_cnt += 3;
2232 inodes->bytes_missing += c - inodes->bytes_left;
2233 inodes->bytes_left = 0;
2234 inodes->elem_missed += 3;
2240 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
2241 struct btrfs_path *path,
2242 void *ctx, bool ignore_offset)
2245 u64 extent_item_pos;
2247 struct btrfs_key found_key;
2248 int search_commit_root = path->search_commit_root;
2250 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
2251 btrfs_release_path(path);
2254 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2257 extent_item_pos = logical - found_key.objectid;
2258 ret = iterate_extent_inodes(fs_info, found_key.objectid,
2259 extent_item_pos, search_commit_root,
2260 build_ino_list, ctx, ignore_offset);
2265 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2266 struct extent_buffer *eb, struct inode_fs_paths *ipath);
2268 static int iterate_inode_refs(u64 inum, struct inode_fs_paths *ipath)
2277 struct btrfs_root *fs_root = ipath->fs_root;
2278 struct btrfs_path *path = ipath->btrfs_path;
2279 struct extent_buffer *eb;
2280 struct btrfs_inode_ref *iref;
2281 struct btrfs_key found_key;
2284 ret = btrfs_find_item(fs_root, path, inum,
2285 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2291 ret = found ? 0 : -ENOENT;
2296 parent = found_key.offset;
2297 slot = path->slots[0];
2298 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2303 btrfs_release_path(path);
2305 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2307 for (cur = 0; cur < btrfs_item_size(eb, slot); cur += len) {
2308 name_len = btrfs_inode_ref_name_len(eb, iref);
2309 /* path must be released before calling iterate()! */
2310 btrfs_debug(fs_root->fs_info,
2311 "following ref at offset %u for inode %llu in tree %llu",
2312 cur, found_key.objectid,
2313 fs_root->root_key.objectid);
2314 ret = inode_to_path(parent, name_len,
2315 (unsigned long)(iref + 1), eb, ipath);
2318 len = sizeof(*iref) + name_len;
2319 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2321 free_extent_buffer(eb);
2324 btrfs_release_path(path);
2329 static int iterate_inode_extrefs(u64 inum, struct inode_fs_paths *ipath)
2336 struct btrfs_root *fs_root = ipath->fs_root;
2337 struct btrfs_path *path = ipath->btrfs_path;
2338 struct extent_buffer *eb;
2339 struct btrfs_inode_extref *extref;
2345 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2350 ret = found ? 0 : -ENOENT;
2355 slot = path->slots[0];
2356 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2361 btrfs_release_path(path);
2363 item_size = btrfs_item_size(eb, slot);
2364 ptr = btrfs_item_ptr_offset(eb, slot);
2367 while (cur_offset < item_size) {
2370 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2371 parent = btrfs_inode_extref_parent(eb, extref);
2372 name_len = btrfs_inode_extref_name_len(eb, extref);
2373 ret = inode_to_path(parent, name_len,
2374 (unsigned long)&extref->name, eb, ipath);
2378 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2379 cur_offset += sizeof(*extref);
2381 free_extent_buffer(eb);
2386 btrfs_release_path(path);
2392 * returns 0 if the path could be dumped (probably truncated)
2393 * returns <0 in case of an error
2395 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2396 struct extent_buffer *eb, struct inode_fs_paths *ipath)
2400 int i = ipath->fspath->elem_cnt;
2401 const int s_ptr = sizeof(char *);
2404 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2405 ipath->fspath->bytes_left - s_ptr : 0;
2407 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2408 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2409 name_off, eb, inum, fspath_min, bytes_left);
2411 return PTR_ERR(fspath);
2413 if (fspath > fspath_min) {
2414 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2415 ++ipath->fspath->elem_cnt;
2416 ipath->fspath->bytes_left = fspath - fspath_min;
2418 ++ipath->fspath->elem_missed;
2419 ipath->fspath->bytes_missing += fspath_min - fspath;
2420 ipath->fspath->bytes_left = 0;
2427 * this dumps all file system paths to the inode into the ipath struct, provided
2428 * is has been created large enough. each path is zero-terminated and accessed
2429 * from ipath->fspath->val[i].
2430 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2431 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2432 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2433 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2434 * have been needed to return all paths.
2436 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2441 ret = iterate_inode_refs(inum, ipath);
2444 else if (ret != -ENOENT)
2447 ret = iterate_inode_extrefs(inum, ipath);
2448 if (ret == -ENOENT && found_refs)
2454 struct btrfs_data_container *init_data_container(u32 total_bytes)
2456 struct btrfs_data_container *data;
2459 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2460 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2462 return ERR_PTR(-ENOMEM);
2464 if (total_bytes >= sizeof(*data)) {
2465 data->bytes_left = total_bytes - sizeof(*data);
2466 data->bytes_missing = 0;
2468 data->bytes_missing = sizeof(*data) - total_bytes;
2469 data->bytes_left = 0;
2473 data->elem_missed = 0;
2479 * allocates space to return multiple file system paths for an inode.
2480 * total_bytes to allocate are passed, note that space usable for actual path
2481 * information will be total_bytes - sizeof(struct inode_fs_paths).
2482 * the returned pointer must be freed with free_ipath() in the end.
2484 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2485 struct btrfs_path *path)
2487 struct inode_fs_paths *ifp;
2488 struct btrfs_data_container *fspath;
2490 fspath = init_data_container(total_bytes);
2492 return ERR_CAST(fspath);
2494 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2497 return ERR_PTR(-ENOMEM);
2500 ifp->btrfs_path = path;
2501 ifp->fspath = fspath;
2502 ifp->fs_root = fs_root;
2507 void free_ipath(struct inode_fs_paths *ipath)
2511 kvfree(ipath->fspath);
2515 struct btrfs_backref_iter *btrfs_backref_iter_alloc(
2516 struct btrfs_fs_info *fs_info, gfp_t gfp_flag)
2518 struct btrfs_backref_iter *ret;
2520 ret = kzalloc(sizeof(*ret), gfp_flag);
2524 ret->path = btrfs_alloc_path();
2530 /* Current backref iterator only supports iteration in commit root */
2531 ret->path->search_commit_root = 1;
2532 ret->path->skip_locking = 1;
2533 ret->fs_info = fs_info;
2538 int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr)
2540 struct btrfs_fs_info *fs_info = iter->fs_info;
2541 struct btrfs_root *extent_root = btrfs_extent_root(fs_info, bytenr);
2542 struct btrfs_path *path = iter->path;
2543 struct btrfs_extent_item *ei;
2544 struct btrfs_key key;
2547 key.objectid = bytenr;
2548 key.type = BTRFS_METADATA_ITEM_KEY;
2549 key.offset = (u64)-1;
2550 iter->bytenr = bytenr;
2552 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
2559 if (path->slots[0] == 0) {
2560 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
2566 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
2567 if ((key.type != BTRFS_EXTENT_ITEM_KEY &&
2568 key.type != BTRFS_METADATA_ITEM_KEY) || key.objectid != bytenr) {
2572 memcpy(&iter->cur_key, &key, sizeof(key));
2573 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2575 iter->end_ptr = (u32)(iter->item_ptr +
2576 btrfs_item_size(path->nodes[0], path->slots[0]));
2577 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
2578 struct btrfs_extent_item);
2581 * Only support iteration on tree backref yet.
2583 * This is an extra precaution for non skinny-metadata, where
2584 * EXTENT_ITEM is also used for tree blocks, that we can only use
2585 * extent flags to determine if it's a tree block.
2587 if (btrfs_extent_flags(path->nodes[0], ei) & BTRFS_EXTENT_FLAG_DATA) {
2591 iter->cur_ptr = (u32)(iter->item_ptr + sizeof(*ei));
2593 /* If there is no inline backref, go search for keyed backref */
2594 if (iter->cur_ptr >= iter->end_ptr) {
2595 ret = btrfs_next_item(extent_root, path);
2597 /* No inline nor keyed ref */
2605 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key,
2607 if (iter->cur_key.objectid != bytenr ||
2608 (iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY &&
2609 iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY)) {
2613 iter->cur_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2615 iter->item_ptr = iter->cur_ptr;
2616 iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size(
2617 path->nodes[0], path->slots[0]));
2622 btrfs_backref_iter_release(iter);
2627 * Go to the next backref item of current bytenr, can be either inlined or
2630 * Caller needs to check whether it's inline ref or not by iter->cur_key.
2632 * Return 0 if we get next backref without problem.
2633 * Return >0 if there is no extra backref for this bytenr.
2634 * Return <0 if there is something wrong happened.
2636 int btrfs_backref_iter_next(struct btrfs_backref_iter *iter)
2638 struct extent_buffer *eb = btrfs_backref_get_eb(iter);
2639 struct btrfs_root *extent_root;
2640 struct btrfs_path *path = iter->path;
2641 struct btrfs_extent_inline_ref *iref;
2645 if (btrfs_backref_iter_is_inline_ref(iter)) {
2646 /* We're still inside the inline refs */
2647 ASSERT(iter->cur_ptr < iter->end_ptr);
2649 if (btrfs_backref_has_tree_block_info(iter)) {
2650 /* First tree block info */
2651 size = sizeof(struct btrfs_tree_block_info);
2653 /* Use inline ref type to determine the size */
2656 iref = (struct btrfs_extent_inline_ref *)
2657 ((unsigned long)iter->cur_ptr);
2658 type = btrfs_extent_inline_ref_type(eb, iref);
2660 size = btrfs_extent_inline_ref_size(type);
2662 iter->cur_ptr += size;
2663 if (iter->cur_ptr < iter->end_ptr)
2666 /* All inline items iterated, fall through */
2669 /* We're at keyed items, there is no inline item, go to the next one */
2670 extent_root = btrfs_extent_root(iter->fs_info, iter->bytenr);
2671 ret = btrfs_next_item(extent_root, iter->path);
2675 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]);
2676 if (iter->cur_key.objectid != iter->bytenr ||
2677 (iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY &&
2678 iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY))
2680 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
2682 iter->cur_ptr = iter->item_ptr;
2683 iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size(path->nodes[0],
2688 void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
2689 struct btrfs_backref_cache *cache, int is_reloc)
2693 cache->rb_root = RB_ROOT;
2694 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
2695 INIT_LIST_HEAD(&cache->pending[i]);
2696 INIT_LIST_HEAD(&cache->changed);
2697 INIT_LIST_HEAD(&cache->detached);
2698 INIT_LIST_HEAD(&cache->leaves);
2699 INIT_LIST_HEAD(&cache->pending_edge);
2700 INIT_LIST_HEAD(&cache->useless_node);
2701 cache->fs_info = fs_info;
2702 cache->is_reloc = is_reloc;
2705 struct btrfs_backref_node *btrfs_backref_alloc_node(
2706 struct btrfs_backref_cache *cache, u64 bytenr, int level)
2708 struct btrfs_backref_node *node;
2710 ASSERT(level >= 0 && level < BTRFS_MAX_LEVEL);
2711 node = kzalloc(sizeof(*node), GFP_NOFS);
2715 INIT_LIST_HEAD(&node->list);
2716 INIT_LIST_HEAD(&node->upper);
2717 INIT_LIST_HEAD(&node->lower);
2718 RB_CLEAR_NODE(&node->rb_node);
2720 node->level = level;
2721 node->bytenr = bytenr;
2726 struct btrfs_backref_edge *btrfs_backref_alloc_edge(
2727 struct btrfs_backref_cache *cache)
2729 struct btrfs_backref_edge *edge;
2731 edge = kzalloc(sizeof(*edge), GFP_NOFS);
2738 * Drop the backref node from cache, also cleaning up all its
2739 * upper edges and any uncached nodes in the path.
2741 * This cleanup happens bottom up, thus the node should either
2742 * be the lowest node in the cache or a detached node.
2744 void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
2745 struct btrfs_backref_node *node)
2747 struct btrfs_backref_node *upper;
2748 struct btrfs_backref_edge *edge;
2753 BUG_ON(!node->lowest && !node->detached);
2754 while (!list_empty(&node->upper)) {
2755 edge = list_entry(node->upper.next, struct btrfs_backref_edge,
2757 upper = edge->node[UPPER];
2758 list_del(&edge->list[LOWER]);
2759 list_del(&edge->list[UPPER]);
2760 btrfs_backref_free_edge(cache, edge);
2763 * Add the node to leaf node list if no other child block
2766 if (list_empty(&upper->lower)) {
2767 list_add_tail(&upper->lower, &cache->leaves);
2772 btrfs_backref_drop_node(cache, node);
2776 * Release all nodes/edges from current cache
2778 void btrfs_backref_release_cache(struct btrfs_backref_cache *cache)
2780 struct btrfs_backref_node *node;
2783 while (!list_empty(&cache->detached)) {
2784 node = list_entry(cache->detached.next,
2785 struct btrfs_backref_node, list);
2786 btrfs_backref_cleanup_node(cache, node);
2789 while (!list_empty(&cache->leaves)) {
2790 node = list_entry(cache->leaves.next,
2791 struct btrfs_backref_node, lower);
2792 btrfs_backref_cleanup_node(cache, node);
2795 cache->last_trans = 0;
2797 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
2798 ASSERT(list_empty(&cache->pending[i]));
2799 ASSERT(list_empty(&cache->pending_edge));
2800 ASSERT(list_empty(&cache->useless_node));
2801 ASSERT(list_empty(&cache->changed));
2802 ASSERT(list_empty(&cache->detached));
2803 ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
2804 ASSERT(!cache->nr_nodes);
2805 ASSERT(!cache->nr_edges);
2809 * Handle direct tree backref
2811 * Direct tree backref means, the backref item shows its parent bytenr
2812 * directly. This is for SHARED_BLOCK_REF backref (keyed or inlined).
2814 * @ref_key: The converted backref key.
2815 * For keyed backref, it's the item key.
2816 * For inlined backref, objectid is the bytenr,
2817 * type is btrfs_inline_ref_type, offset is
2818 * btrfs_inline_ref_offset.
2820 static int handle_direct_tree_backref(struct btrfs_backref_cache *cache,
2821 struct btrfs_key *ref_key,
2822 struct btrfs_backref_node *cur)
2824 struct btrfs_backref_edge *edge;
2825 struct btrfs_backref_node *upper;
2826 struct rb_node *rb_node;
2828 ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY);
2830 /* Only reloc root uses backref pointing to itself */
2831 if (ref_key->objectid == ref_key->offset) {
2832 struct btrfs_root *root;
2834 cur->is_reloc_root = 1;
2835 /* Only reloc backref cache cares about a specific root */
2836 if (cache->is_reloc) {
2837 root = find_reloc_root(cache->fs_info, cur->bytenr);
2843 * For generic purpose backref cache, reloc root node
2846 list_add(&cur->list, &cache->useless_node);
2851 edge = btrfs_backref_alloc_edge(cache);
2855 rb_node = rb_simple_search(&cache->rb_root, ref_key->offset);
2857 /* Parent node not yet cached */
2858 upper = btrfs_backref_alloc_node(cache, ref_key->offset,
2861 btrfs_backref_free_edge(cache, edge);
2866 * Backrefs for the upper level block isn't cached, add the
2867 * block to pending list
2869 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
2871 /* Parent node already cached */
2872 upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
2873 ASSERT(upper->checked);
2874 INIT_LIST_HEAD(&edge->list[UPPER]);
2876 btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER);
2881 * Handle indirect tree backref
2883 * Indirect tree backref means, we only know which tree the node belongs to.
2884 * We still need to do a tree search to find out the parents. This is for
2885 * TREE_BLOCK_REF backref (keyed or inlined).
2887 * @ref_key: The same as @ref_key in handle_direct_tree_backref()
2888 * @tree_key: The first key of this tree block.
2889 * @path: A clean (released) path, to avoid allocating path every time
2890 * the function get called.
2892 static int handle_indirect_tree_backref(struct btrfs_backref_cache *cache,
2893 struct btrfs_path *path,
2894 struct btrfs_key *ref_key,
2895 struct btrfs_key *tree_key,
2896 struct btrfs_backref_node *cur)
2898 struct btrfs_fs_info *fs_info = cache->fs_info;
2899 struct btrfs_backref_node *upper;
2900 struct btrfs_backref_node *lower;
2901 struct btrfs_backref_edge *edge;
2902 struct extent_buffer *eb;
2903 struct btrfs_root *root;
2904 struct rb_node *rb_node;
2906 bool need_check = true;
2909 root = btrfs_get_fs_root(fs_info, ref_key->offset, false);
2911 return PTR_ERR(root);
2912 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
2915 if (btrfs_root_level(&root->root_item) == cur->level) {
2917 ASSERT(btrfs_root_bytenr(&root->root_item) == cur->bytenr);
2919 * For reloc backref cache, we may ignore reloc root. But for
2920 * general purpose backref cache, we can't rely on
2921 * btrfs_should_ignore_reloc_root() as it may conflict with
2922 * current running relocation and lead to missing root.
2924 * For general purpose backref cache, reloc root detection is
2925 * completely relying on direct backref (key->offset is parent
2926 * bytenr), thus only do such check for reloc cache.
2928 if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) {
2929 btrfs_put_root(root);
2930 list_add(&cur->list, &cache->useless_node);
2937 level = cur->level + 1;
2939 /* Search the tree to find parent blocks referring to the block */
2940 path->search_commit_root = 1;
2941 path->skip_locking = 1;
2942 path->lowest_level = level;
2943 ret = btrfs_search_slot(NULL, root, tree_key, path, 0, 0);
2944 path->lowest_level = 0;
2946 btrfs_put_root(root);
2949 if (ret > 0 && path->slots[level] > 0)
2950 path->slots[level]--;
2952 eb = path->nodes[level];
2953 if (btrfs_node_blockptr(eb, path->slots[level]) != cur->bytenr) {
2955 "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
2956 cur->bytenr, level - 1, root->root_key.objectid,
2957 tree_key->objectid, tree_key->type, tree_key->offset);
2958 btrfs_put_root(root);
2964 /* Add all nodes and edges in the path */
2965 for (; level < BTRFS_MAX_LEVEL; level++) {
2966 if (!path->nodes[level]) {
2967 ASSERT(btrfs_root_bytenr(&root->root_item) ==
2969 /* Same as previous should_ignore_reloc_root() call */
2970 if (btrfs_should_ignore_reloc_root(root) &&
2972 btrfs_put_root(root);
2973 list_add(&lower->list, &cache->useless_node);
2980 edge = btrfs_backref_alloc_edge(cache);
2982 btrfs_put_root(root);
2987 eb = path->nodes[level];
2988 rb_node = rb_simple_search(&cache->rb_root, eb->start);
2990 upper = btrfs_backref_alloc_node(cache, eb->start,
2993 btrfs_put_root(root);
2994 btrfs_backref_free_edge(cache, edge);
2998 upper->owner = btrfs_header_owner(eb);
2999 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
3003 * If we know the block isn't shared we can avoid
3004 * checking its backrefs.
3006 if (btrfs_block_can_be_shared(root, eb))
3012 * Add the block to pending list if we need to check its
3013 * backrefs, we only do this once while walking up a
3014 * tree as we will catch anything else later on.
3016 if (!upper->checked && need_check) {
3018 list_add_tail(&edge->list[UPPER],
3019 &cache->pending_edge);
3023 INIT_LIST_HEAD(&edge->list[UPPER]);
3026 upper = rb_entry(rb_node, struct btrfs_backref_node,
3028 ASSERT(upper->checked);
3029 INIT_LIST_HEAD(&edge->list[UPPER]);
3031 upper->owner = btrfs_header_owner(eb);
3033 btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER);
3036 btrfs_put_root(root);
3043 btrfs_release_path(path);
3048 * Add backref node @cur into @cache.
3050 * NOTE: Even if the function returned 0, @cur is not yet cached as its upper
3051 * links aren't yet bi-directional. Needs to finish such links.
3052 * Use btrfs_backref_finish_upper_links() to finish such linkage.
3054 * @path: Released path for indirect tree backref lookup
3055 * @iter: Released backref iter for extent tree search
3056 * @node_key: The first key of the tree block
3058 int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
3059 struct btrfs_path *path,
3060 struct btrfs_backref_iter *iter,
3061 struct btrfs_key *node_key,
3062 struct btrfs_backref_node *cur)
3064 struct btrfs_fs_info *fs_info = cache->fs_info;
3065 struct btrfs_backref_edge *edge;
3066 struct btrfs_backref_node *exist;
3069 ret = btrfs_backref_iter_start(iter, cur->bytenr);
3073 * We skip the first btrfs_tree_block_info, as we don't use the key
3074 * stored in it, but fetch it from the tree block
3076 if (btrfs_backref_has_tree_block_info(iter)) {
3077 ret = btrfs_backref_iter_next(iter);
3080 /* No extra backref? This means the tree block is corrupted */
3086 WARN_ON(cur->checked);
3087 if (!list_empty(&cur->upper)) {
3089 * The backref was added previously when processing backref of
3090 * type BTRFS_TREE_BLOCK_REF_KEY
3092 ASSERT(list_is_singular(&cur->upper));
3093 edge = list_entry(cur->upper.next, struct btrfs_backref_edge,
3095 ASSERT(list_empty(&edge->list[UPPER]));
3096 exist = edge->node[UPPER];
3098 * Add the upper level block to pending list if we need check
3101 if (!exist->checked)
3102 list_add_tail(&edge->list[UPPER], &cache->pending_edge);
3107 for (; ret == 0; ret = btrfs_backref_iter_next(iter)) {
3108 struct extent_buffer *eb;
3109 struct btrfs_key key;
3113 eb = btrfs_backref_get_eb(iter);
3115 key.objectid = iter->bytenr;
3116 if (btrfs_backref_iter_is_inline_ref(iter)) {
3117 struct btrfs_extent_inline_ref *iref;
3119 /* Update key for inline backref */
3120 iref = (struct btrfs_extent_inline_ref *)
3121 ((unsigned long)iter->cur_ptr);
3122 type = btrfs_get_extent_inline_ref_type(eb, iref,
3123 BTRFS_REF_TYPE_BLOCK);
3124 if (type == BTRFS_REF_TYPE_INVALID) {
3129 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3131 key.type = iter->cur_key.type;
3132 key.offset = iter->cur_key.offset;
3136 * Parent node found and matches current inline ref, no need to
3137 * rebuild this node for this inline ref
3140 ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
3141 exist->owner == key.offset) ||
3142 (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
3143 exist->bytenr == key.offset))) {
3148 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */
3149 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
3150 ret = handle_direct_tree_backref(cache, &key, cur);
3154 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
3156 btrfs_print_v0_err(fs_info);
3157 btrfs_handle_fs_error(fs_info, ret, NULL);
3159 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
3164 * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset
3165 * means the root objectid. We need to search the tree to get
3166 * its parent bytenr.
3168 ret = handle_indirect_tree_backref(cache, path, &key, node_key,
3177 btrfs_backref_iter_release(iter);
3182 * Finish the upwards linkage created by btrfs_backref_add_tree_node()
3184 int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
3185 struct btrfs_backref_node *start)
3187 struct list_head *useless_node = &cache->useless_node;
3188 struct btrfs_backref_edge *edge;
3189 struct rb_node *rb_node;
3190 LIST_HEAD(pending_edge);
3192 ASSERT(start->checked);
3194 /* Insert this node to cache if it's not COW-only */
3195 if (!start->cowonly) {
3196 rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
3199 btrfs_backref_panic(cache->fs_info, start->bytenr,
3201 list_add_tail(&start->lower, &cache->leaves);
3205 * Use breadth first search to iterate all related edges.
3207 * The starting points are all the edges of this node
3209 list_for_each_entry(edge, &start->upper, list[LOWER])
3210 list_add_tail(&edge->list[UPPER], &pending_edge);
3212 while (!list_empty(&pending_edge)) {
3213 struct btrfs_backref_node *upper;
3214 struct btrfs_backref_node *lower;
3216 edge = list_first_entry(&pending_edge,
3217 struct btrfs_backref_edge, list[UPPER]);
3218 list_del_init(&edge->list[UPPER]);
3219 upper = edge->node[UPPER];
3220 lower = edge->node[LOWER];
3222 /* Parent is detached, no need to keep any edges */
3223 if (upper->detached) {
3224 list_del(&edge->list[LOWER]);
3225 btrfs_backref_free_edge(cache, edge);
3227 /* Lower node is orphan, queue for cleanup */
3228 if (list_empty(&lower->upper))
3229 list_add(&lower->list, useless_node);
3234 * All new nodes added in current build_backref_tree() haven't
3235 * been linked to the cache rb tree.
3236 * So if we have upper->rb_node populated, this means a cache
3237 * hit. We only need to link the edge, as @upper and all its
3238 * parents have already been linked.
3240 if (!RB_EMPTY_NODE(&upper->rb_node)) {
3241 if (upper->lowest) {
3242 list_del_init(&upper->lower);
3246 list_add_tail(&edge->list[UPPER], &upper->lower);
3250 /* Sanity check, we shouldn't have any unchecked nodes */
3251 if (!upper->checked) {
3256 /* Sanity check, COW-only node has non-COW-only parent */
3257 if (start->cowonly != upper->cowonly) {
3262 /* Only cache non-COW-only (subvolume trees) tree blocks */
3263 if (!upper->cowonly) {
3264 rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
3267 btrfs_backref_panic(cache->fs_info,
3268 upper->bytenr, -EEXIST);
3273 list_add_tail(&edge->list[UPPER], &upper->lower);
3276 * Also queue all the parent edges of this uncached node
3277 * to finish the upper linkage
3279 list_for_each_entry(edge, &upper->upper, list[LOWER])
3280 list_add_tail(&edge->list[UPPER], &pending_edge);
3285 void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
3286 struct btrfs_backref_node *node)
3288 struct btrfs_backref_node *lower;
3289 struct btrfs_backref_node *upper;
3290 struct btrfs_backref_edge *edge;
3292 while (!list_empty(&cache->useless_node)) {
3293 lower = list_first_entry(&cache->useless_node,
3294 struct btrfs_backref_node, list);
3295 list_del_init(&lower->list);
3297 while (!list_empty(&cache->pending_edge)) {
3298 edge = list_first_entry(&cache->pending_edge,
3299 struct btrfs_backref_edge, list[UPPER]);
3300 list_del(&edge->list[UPPER]);
3301 list_del(&edge->list[LOWER]);
3302 lower = edge->node[LOWER];
3303 upper = edge->node[UPPER];
3304 btrfs_backref_free_edge(cache, edge);
3307 * Lower is no longer linked to any upper backref nodes and
3308 * isn't in the cache, we can free it ourselves.
3310 if (list_empty(&lower->upper) &&
3311 RB_EMPTY_NODE(&lower->rb_node))
3312 list_add(&lower->list, &cache->useless_node);
3314 if (!RB_EMPTY_NODE(&upper->rb_node))
3317 /* Add this guy's upper edges to the list to process */
3318 list_for_each_entry(edge, &upper->upper, list[LOWER])
3319 list_add_tail(&edge->list[UPPER],
3320 &cache->pending_edge);
3321 if (list_empty(&upper->upper))
3322 list_add(&upper->list, &cache->useless_node);
3325 while (!list_empty(&cache->useless_node)) {
3326 lower = list_first_entry(&cache->useless_node,
3327 struct btrfs_backref_node, list);
3328 list_del_init(&lower->list);
3331 btrfs_backref_drop_node(cache, lower);
3334 btrfs_backref_cleanup_node(cache, node);
3335 ASSERT(list_empty(&cache->useless_node) &&
3336 list_empty(&cache->pending_edge));