2 * Copyright (C) 2011 STRATO. All rights reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
20 #include <linux/rbtree.h>
21 #include <trace/events/btrfs.h>
26 #include "transaction.h"
27 #include "delayed-ref.h"
30 /* Just an arbitrary number so we can be sure this happened */
31 #define BACKREF_FOUND_SHARED 6
33 struct extent_inode_elem {
36 struct extent_inode_elem *next;
39 static int check_extent_in_eb(const struct btrfs_key *key,
40 const struct extent_buffer *eb,
41 const struct btrfs_file_extent_item *fi,
43 struct extent_inode_elem **eie)
46 struct extent_inode_elem *e;
48 if (!btrfs_file_extent_compression(eb, fi) &&
49 !btrfs_file_extent_encryption(eb, fi) &&
50 !btrfs_file_extent_other_encoding(eb, fi)) {
54 data_offset = btrfs_file_extent_offset(eb, fi);
55 data_len = btrfs_file_extent_num_bytes(eb, fi);
57 if (extent_item_pos < data_offset ||
58 extent_item_pos >= data_offset + data_len)
60 offset = extent_item_pos - data_offset;
63 e = kmalloc(sizeof(*e), GFP_NOFS);
68 e->inum = key->objectid;
69 e->offset = key->offset + offset;
75 static void free_inode_elem_list(struct extent_inode_elem *eie)
77 struct extent_inode_elem *eie_next;
79 for (; eie; eie = eie_next) {
85 static int find_extent_in_eb(const struct extent_buffer *eb,
86 u64 wanted_disk_byte, u64 extent_item_pos,
87 struct extent_inode_elem **eie)
91 struct btrfs_file_extent_item *fi;
98 * from the shared data ref, we only have the leaf but we need
99 * the key. thus, we must look into all items and see that we
100 * find one (some) with a reference to our extent item.
102 nritems = btrfs_header_nritems(eb);
103 for (slot = 0; slot < nritems; ++slot) {
104 btrfs_item_key_to_cpu(eb, &key, slot);
105 if (key.type != BTRFS_EXTENT_DATA_KEY)
107 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
108 extent_type = btrfs_file_extent_type(eb, fi);
109 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
111 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
112 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
113 if (disk_byte != wanted_disk_byte)
116 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
129 #define PREFTREE_INIT { .root = RB_ROOT, .count = 0 }
132 struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */
133 struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */
134 struct preftree indirect_missing_keys;
138 * Checks for a shared extent during backref search.
140 * The share_count tracks prelim_refs (direct and indirect) having a
142 * - incremented when a ref->count transitions to >0
143 * - decremented when a ref->count transitions to <1
149 bool have_delayed_delete_refs;
152 static inline int extent_is_shared(struct share_check *sc)
154 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
157 static struct kmem_cache *btrfs_prelim_ref_cache;
159 int __init btrfs_prelim_ref_init(void)
161 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
162 sizeof(struct prelim_ref),
166 if (!btrfs_prelim_ref_cache)
171 void btrfs_prelim_ref_exit(void)
173 kmem_cache_destroy(btrfs_prelim_ref_cache);
176 static void free_pref(struct prelim_ref *ref)
178 kmem_cache_free(btrfs_prelim_ref_cache, ref);
182 * Return 0 when both refs are for the same block (and can be merged).
183 * A -1 return indicates ref1 is a 'lower' block than ref2, while 1
184 * indicates a 'higher' block.
186 static int prelim_ref_compare(struct prelim_ref *ref1,
187 struct prelim_ref *ref2)
189 if (ref1->level < ref2->level)
191 if (ref1->level > ref2->level)
193 if (ref1->root_id < ref2->root_id)
195 if (ref1->root_id > ref2->root_id)
197 if (ref1->key_for_search.type < ref2->key_for_search.type)
199 if (ref1->key_for_search.type > ref2->key_for_search.type)
201 if (ref1->key_for_search.objectid < ref2->key_for_search.objectid)
203 if (ref1->key_for_search.objectid > ref2->key_for_search.objectid)
205 if (ref1->key_for_search.offset < ref2->key_for_search.offset)
207 if (ref1->key_for_search.offset > ref2->key_for_search.offset)
209 if (ref1->parent < ref2->parent)
211 if (ref1->parent > ref2->parent)
217 void update_share_count(struct share_check *sc, int oldcount, int newcount)
219 if ((!sc) || (oldcount == 0 && newcount < 1))
222 if (oldcount > 0 && newcount < 1)
224 else if (oldcount < 1 && newcount > 0)
229 * Add @newref to the @root rbtree, merging identical refs.
231 * Callers should assume that newref has been freed after calling.
233 static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
234 struct preftree *preftree,
235 struct prelim_ref *newref,
236 struct share_check *sc)
238 struct rb_root *root;
240 struct rb_node *parent = NULL;
241 struct prelim_ref *ref;
244 root = &preftree->root;
249 ref = rb_entry(parent, struct prelim_ref, rbnode);
250 result = prelim_ref_compare(ref, newref);
253 } else if (result > 0) {
256 /* Identical refs, merge them and free @newref */
257 struct extent_inode_elem *eie = ref->inode_list;
259 while (eie && eie->next)
263 ref->inode_list = newref->inode_list;
265 eie->next = newref->inode_list;
266 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
269 * A delayed ref can have newref->count < 0.
270 * The ref->count is updated to follow any
271 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
273 update_share_count(sc, ref->count,
274 ref->count + newref->count);
275 ref->count += newref->count;
281 update_share_count(sc, 0, newref->count);
283 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
284 rb_link_node(&newref->rbnode, parent, p);
285 rb_insert_color(&newref->rbnode, root);
289 * Release the entire tree. We don't care about internal consistency so
290 * just free everything and then reset the tree root.
292 static void prelim_release(struct preftree *preftree)
294 struct prelim_ref *ref, *next_ref;
296 rbtree_postorder_for_each_entry_safe(ref, next_ref, &preftree->root,
300 preftree->root = RB_ROOT;
305 * the rules for all callers of this function are:
306 * - obtaining the parent is the goal
307 * - if you add a key, you must know that it is a correct key
308 * - if you cannot add the parent or a correct key, then we will look into the
309 * block later to set a correct key
313 * backref type | shared | indirect | shared | indirect
314 * information | tree | tree | data | data
315 * --------------------+--------+----------+--------+----------
316 * parent logical | y | - | - | -
317 * key to resolve | - | y | y | y
318 * tree block logical | - | - | - | -
319 * root for resolving | y | y | y | y
321 * - column 1: we've the parent -> done
322 * - column 2, 3, 4: we use the key to find the parent
324 * on disk refs (inline or keyed)
325 * ==============================
326 * backref type | shared | indirect | shared | indirect
327 * information | tree | tree | data | data
328 * --------------------+--------+----------+--------+----------
329 * parent logical | y | - | y | -
330 * key to resolve | - | - | - | y
331 * tree block logical | y | y | y | y
332 * root for resolving | - | y | y | y
334 * - column 1, 3: we've the parent -> done
335 * - column 2: we take the first key from the block to find the parent
336 * (see add_missing_keys)
337 * - column 4: we use the key to find the parent
339 * additional information that's available but not required to find the parent
340 * block might help in merging entries to gain some speed.
342 static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
343 struct preftree *preftree, u64 root_id,
344 const struct btrfs_key *key, int level, u64 parent,
345 u64 wanted_disk_byte, int count,
346 struct share_check *sc, gfp_t gfp_mask)
348 struct prelim_ref *ref;
350 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
353 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
357 ref->root_id = root_id;
359 ref->key_for_search = *key;
361 * We can often find data backrefs with an offset that is too
362 * large (>= LLONG_MAX, maximum allowed file offset) due to
363 * underflows when subtracting a file's offset with the data
364 * offset of its corresponding extent data item. This can
365 * happen for example in the clone ioctl.
366 * So if we detect such case we set the search key's offset to
367 * zero to make sure we will find the matching file extent item
368 * at add_all_parents(), otherwise we will miss it because the
369 * offset taken form the backref is much larger then the offset
370 * of the file extent item. This can make us scan a very large
371 * number of file extent items, but at least it will not make
373 * This is an ugly workaround for a behaviour that should have
374 * never existed, but it does and a fix for the clone ioctl
375 * would touch a lot of places, cause backwards incompatibility
376 * and would not fix the problem for extents cloned with older
379 if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY &&
380 ref->key_for_search.offset >= LLONG_MAX)
381 ref->key_for_search.offset = 0;
383 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
386 ref->inode_list = NULL;
389 ref->parent = parent;
390 ref->wanted_disk_byte = wanted_disk_byte;
391 prelim_ref_insert(fs_info, preftree, ref, sc);
392 return extent_is_shared(sc);
395 /* direct refs use root == 0, key == NULL */
396 static int add_direct_ref(const struct btrfs_fs_info *fs_info,
397 struct preftrees *preftrees, int level, u64 parent,
398 u64 wanted_disk_byte, int count,
399 struct share_check *sc, gfp_t gfp_mask)
401 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
402 parent, wanted_disk_byte, count, sc, gfp_mask);
405 /* indirect refs use parent == 0 */
406 static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
407 struct preftrees *preftrees, u64 root_id,
408 const struct btrfs_key *key, int level,
409 u64 wanted_disk_byte, int count,
410 struct share_check *sc, gfp_t gfp_mask)
412 struct preftree *tree = &preftrees->indirect;
415 tree = &preftrees->indirect_missing_keys;
416 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
417 wanted_disk_byte, count, sc, gfp_mask);
420 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
421 struct ulist *parents, struct prelim_ref *ref,
422 int level, u64 time_seq, const u64 *extent_item_pos,
427 struct extent_buffer *eb;
428 struct btrfs_key key;
429 struct btrfs_key *key_for_search = &ref->key_for_search;
430 struct btrfs_file_extent_item *fi;
431 struct extent_inode_elem *eie = NULL, *old = NULL;
433 u64 wanted_disk_byte = ref->wanted_disk_byte;
437 eb = path->nodes[level];
438 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
445 * We normally enter this function with the path already pointing to
446 * the first item to check. But sometimes, we may enter it with
447 * slot==nritems. In that case, go to the next leaf before we continue.
449 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
450 if (time_seq == SEQ_LAST)
451 ret = btrfs_next_leaf(root, path);
453 ret = btrfs_next_old_leaf(root, path, time_seq);
456 while (!ret && count < total_refs) {
458 slot = path->slots[0];
460 btrfs_item_key_to_cpu(eb, &key, slot);
462 if (key.objectid != key_for_search->objectid ||
463 key.type != BTRFS_EXTENT_DATA_KEY)
466 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
467 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
469 if (disk_byte == wanted_disk_byte) {
473 if (extent_item_pos) {
474 ret = check_extent_in_eb(&key, eb, fi,
482 ret = ulist_add_merge_ptr(parents, eb->start,
483 eie, (void **)&old, GFP_NOFS);
486 if (!ret && extent_item_pos) {
494 if (time_seq == SEQ_LAST)
495 ret = btrfs_next_item(root, path);
497 ret = btrfs_next_old_item(root, path, time_seq);
503 free_inode_elem_list(eie);
508 * resolve an indirect backref in the form (root_id, key, level)
509 * to a logical address
511 static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
512 struct btrfs_path *path, u64 time_seq,
513 struct prelim_ref *ref, struct ulist *parents,
514 const u64 *extent_item_pos, u64 total_refs)
516 struct btrfs_root *root;
517 struct btrfs_key root_key;
518 struct extent_buffer *eb;
521 int level = ref->level;
524 root_key.objectid = ref->root_id;
525 root_key.type = BTRFS_ROOT_ITEM_KEY;
526 root_key.offset = (u64)-1;
528 index = srcu_read_lock(&fs_info->subvol_srcu);
530 root = btrfs_get_fs_root(fs_info, &root_key, false);
532 srcu_read_unlock(&fs_info->subvol_srcu, index);
537 if (btrfs_is_testing(fs_info)) {
538 srcu_read_unlock(&fs_info->subvol_srcu, index);
543 if (path->search_commit_root)
544 root_level = btrfs_header_level(root->commit_root);
545 else if (time_seq == SEQ_LAST)
546 root_level = btrfs_header_level(root->node);
548 root_level = btrfs_old_root_level(root, time_seq);
550 if (root_level + 1 == level) {
551 srcu_read_unlock(&fs_info->subvol_srcu, index);
555 path->lowest_level = level;
556 if (time_seq == SEQ_LAST)
557 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path,
560 ret = btrfs_search_old_slot(root, &ref->key_for_search, path,
563 /* root node has been locked, we can release @subvol_srcu safely here */
564 srcu_read_unlock(&fs_info->subvol_srcu, index);
567 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
568 ref->root_id, level, ref->count, ret,
569 ref->key_for_search.objectid, ref->key_for_search.type,
570 ref->key_for_search.offset);
574 eb = path->nodes[level];
576 if (WARN_ON(!level)) {
581 eb = path->nodes[level];
584 ret = add_all_parents(root, path, parents, ref, level, time_seq,
585 extent_item_pos, total_refs);
587 path->lowest_level = 0;
588 btrfs_release_path(path);
592 static struct extent_inode_elem *
593 unode_aux_to_inode_list(struct ulist_node *node)
597 return (struct extent_inode_elem *)(uintptr_t)node->aux;
600 static void free_leaf_list(struct ulist *ulist)
602 struct ulist_node *node;
603 struct ulist_iterator uiter;
605 ULIST_ITER_INIT(&uiter);
606 while ((node = ulist_next(ulist, &uiter)))
607 free_inode_elem_list(unode_aux_to_inode_list(node));
613 * We maintain three seperate rbtrees: one for direct refs, one for
614 * indirect refs which have a key, and one for indirect refs which do not
615 * have a key. Each tree does merge on insertion.
617 * Once all of the references are located, we iterate over the tree of
618 * indirect refs with missing keys. An appropriate key is located and
619 * the ref is moved onto the tree for indirect refs. After all missing
620 * keys are thus located, we iterate over the indirect ref tree, resolve
621 * each reference, and then insert the resolved reference onto the
622 * direct tree (merging there too).
624 * New backrefs (i.e., for parent nodes) are added to the appropriate
625 * rbtree as they are encountered. The new backrefs are subsequently
628 static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
629 struct btrfs_path *path, u64 time_seq,
630 struct preftrees *preftrees,
631 const u64 *extent_item_pos, u64 total_refs,
632 struct share_check *sc)
636 struct ulist *parents;
637 struct ulist_node *node;
638 struct ulist_iterator uiter;
639 struct rb_node *rnode;
641 parents = ulist_alloc(GFP_NOFS);
646 * We could trade memory usage for performance here by iterating
647 * the tree, allocating new refs for each insertion, and then
648 * freeing the entire indirect tree when we're done. In some test
649 * cases, the tree can grow quite large (~200k objects).
651 while ((rnode = rb_first(&preftrees->indirect.root))) {
652 struct prelim_ref *ref;
654 ref = rb_entry(rnode, struct prelim_ref, rbnode);
655 if (WARN(ref->parent,
656 "BUG: direct ref found in indirect tree")) {
661 rb_erase(&ref->rbnode, &preftrees->indirect.root);
662 preftrees->indirect.count--;
664 if (ref->count == 0) {
669 if (sc && sc->root_objectid &&
670 ref->root_id != sc->root_objectid) {
672 ret = BACKREF_FOUND_SHARED;
675 err = resolve_indirect_ref(fs_info, path, time_seq, ref,
676 parents, extent_item_pos,
679 * we can only tolerate ENOENT,otherwise,we should catch error
680 * and return directly.
682 if (err == -ENOENT) {
683 prelim_ref_insert(fs_info, &preftrees->direct, ref,
692 /* we put the first parent into the ref at hand */
693 ULIST_ITER_INIT(&uiter);
694 node = ulist_next(parents, &uiter);
695 ref->parent = node ? node->val : 0;
696 ref->inode_list = unode_aux_to_inode_list(node);
698 /* Add a prelim_ref(s) for any other parent(s). */
699 while ((node = ulist_next(parents, &uiter))) {
700 struct prelim_ref *new_ref;
702 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
709 memcpy(new_ref, ref, sizeof(*ref));
710 new_ref->parent = node->val;
711 new_ref->inode_list = unode_aux_to_inode_list(node);
712 prelim_ref_insert(fs_info, &preftrees->direct,
717 * Now it's a direct ref, put it in the the direct tree. We must
718 * do this last because the ref could be merged/freed here.
720 prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL);
722 ulist_reinit(parents);
727 * We may have inode lists attached to refs in the parents ulist, so we
728 * must free them before freeing the ulist and its refs.
730 free_leaf_list(parents);
735 * read tree blocks and add keys where required.
737 static int add_missing_keys(struct btrfs_fs_info *fs_info,
738 struct preftrees *preftrees, bool lock)
740 struct prelim_ref *ref;
741 struct extent_buffer *eb;
742 struct preftree *tree = &preftrees->indirect_missing_keys;
743 struct rb_node *node;
745 while ((node = rb_first(&tree->root))) {
746 ref = rb_entry(node, struct prelim_ref, rbnode);
747 rb_erase(node, &tree->root);
749 BUG_ON(ref->parent); /* should not be a direct ref */
750 BUG_ON(ref->key_for_search.type);
751 BUG_ON(!ref->wanted_disk_byte);
753 eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0);
757 } else if (!extent_buffer_uptodate(eb)) {
759 free_extent_buffer(eb);
763 btrfs_tree_read_lock(eb);
764 if (btrfs_header_level(eb) == 0)
765 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
767 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
769 btrfs_tree_read_unlock(eb);
770 free_extent_buffer(eb);
771 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
778 * add all currently queued delayed refs from this head whose seq nr is
779 * smaller or equal that seq to the list
781 static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
782 struct btrfs_delayed_ref_head *head, u64 seq,
783 struct preftrees *preftrees, u64 *total_refs,
784 struct share_check *sc)
786 struct btrfs_delayed_ref_node *node;
787 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
788 struct btrfs_key key;
789 struct btrfs_key tmp_op_key;
790 struct btrfs_key *op_key = NULL;
794 if (extent_op && extent_op->update_key) {
795 btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
796 op_key = &tmp_op_key;
799 spin_lock(&head->lock);
800 list_for_each_entry(node, &head->ref_list, list) {
804 switch (node->action) {
805 case BTRFS_ADD_DELAYED_EXTENT:
806 case BTRFS_UPDATE_DELAYED_HEAD:
809 case BTRFS_ADD_DELAYED_REF:
810 count = node->ref_mod;
812 case BTRFS_DROP_DELAYED_REF:
813 count = node->ref_mod * -1;
818 *total_refs += count;
819 switch (node->type) {
820 case BTRFS_TREE_BLOCK_REF_KEY: {
821 /* NORMAL INDIRECT METADATA backref */
822 struct btrfs_delayed_tree_ref *ref;
824 ref = btrfs_delayed_node_to_tree_ref(node);
825 ret = add_indirect_ref(fs_info, preftrees, ref->root,
826 &tmp_op_key, ref->level + 1,
827 node->bytenr, count, sc,
831 case BTRFS_SHARED_BLOCK_REF_KEY: {
832 /* SHARED DIRECT METADATA backref */
833 struct btrfs_delayed_tree_ref *ref;
835 ref = btrfs_delayed_node_to_tree_ref(node);
837 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
838 ref->parent, node->bytenr, count,
842 case BTRFS_EXTENT_DATA_REF_KEY: {
843 /* NORMAL INDIRECT DATA backref */
844 struct btrfs_delayed_data_ref *ref;
845 ref = btrfs_delayed_node_to_data_ref(node);
847 key.objectid = ref->objectid;
848 key.type = BTRFS_EXTENT_DATA_KEY;
849 key.offset = ref->offset;
852 * If we have a share check context and a reference for
853 * another inode, we can't exit immediately. This is
854 * because even if this is a BTRFS_ADD_DELAYED_REF
855 * reference we may find next a BTRFS_DROP_DELAYED_REF
856 * which cancels out this ADD reference.
858 * If this is a DROP reference and there was no previous
859 * ADD reference, then we need to signal that when we
860 * process references from the extent tree (through
861 * add_inline_refs() and add_keyed_refs()), we should
862 * not exit early if we find a reference for another
863 * inode, because one of the delayed DROP references
864 * may cancel that reference in the extent tree.
867 sc->have_delayed_delete_refs = true;
869 ret = add_indirect_ref(fs_info, preftrees, ref->root,
870 &key, 0, node->bytenr, count, sc,
874 case BTRFS_SHARED_DATA_REF_KEY: {
875 /* SHARED DIRECT FULL backref */
876 struct btrfs_delayed_data_ref *ref;
878 ref = btrfs_delayed_node_to_data_ref(node);
880 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
881 node->bytenr, count, sc,
889 * We must ignore BACKREF_FOUND_SHARED until all delayed
890 * refs have been checked.
892 if (ret && (ret != BACKREF_FOUND_SHARED))
896 ret = extent_is_shared(sc);
898 spin_unlock(&head->lock);
903 * add all inline backrefs for bytenr to the list
905 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
907 static int add_inline_refs(const struct btrfs_fs_info *fs_info,
908 struct btrfs_path *path, u64 bytenr,
909 int *info_level, struct preftrees *preftrees,
910 u64 *total_refs, struct share_check *sc)
914 struct extent_buffer *leaf;
915 struct btrfs_key key;
916 struct btrfs_key found_key;
919 struct btrfs_extent_item *ei;
924 * enumerate all inline refs
926 leaf = path->nodes[0];
927 slot = path->slots[0];
929 item_size = btrfs_item_size_nr(leaf, slot);
930 BUG_ON(item_size < sizeof(*ei));
932 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
933 flags = btrfs_extent_flags(leaf, ei);
934 *total_refs += btrfs_extent_refs(leaf, ei);
935 btrfs_item_key_to_cpu(leaf, &found_key, slot);
937 ptr = (unsigned long)(ei + 1);
938 end = (unsigned long)ei + item_size;
940 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
941 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
942 struct btrfs_tree_block_info *info;
944 info = (struct btrfs_tree_block_info *)ptr;
945 *info_level = btrfs_tree_block_level(leaf, info);
946 ptr += sizeof(struct btrfs_tree_block_info);
948 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
949 *info_level = found_key.offset;
951 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
955 struct btrfs_extent_inline_ref *iref;
959 iref = (struct btrfs_extent_inline_ref *)ptr;
960 type = btrfs_get_extent_inline_ref_type(leaf, iref,
962 if (type == BTRFS_REF_TYPE_INVALID)
965 offset = btrfs_extent_inline_ref_offset(leaf, iref);
968 case BTRFS_SHARED_BLOCK_REF_KEY:
969 ret = add_direct_ref(fs_info, preftrees,
970 *info_level + 1, offset,
971 bytenr, 1, NULL, GFP_NOFS);
973 case BTRFS_SHARED_DATA_REF_KEY: {
974 struct btrfs_shared_data_ref *sdref;
977 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
978 count = btrfs_shared_data_ref_count(leaf, sdref);
980 ret = add_direct_ref(fs_info, preftrees, 0, offset,
981 bytenr, count, sc, GFP_NOFS);
984 case BTRFS_TREE_BLOCK_REF_KEY:
985 ret = add_indirect_ref(fs_info, preftrees, offset,
986 NULL, *info_level + 1,
987 bytenr, 1, NULL, GFP_NOFS);
989 case BTRFS_EXTENT_DATA_REF_KEY: {
990 struct btrfs_extent_data_ref *dref;
994 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
995 count = btrfs_extent_data_ref_count(leaf, dref);
996 key.objectid = btrfs_extent_data_ref_objectid(leaf,
998 key.type = BTRFS_EXTENT_DATA_KEY;
999 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1001 if (sc && sc->inum && key.objectid != sc->inum &&
1002 !sc->have_delayed_delete_refs) {
1003 ret = BACKREF_FOUND_SHARED;
1007 root = btrfs_extent_data_ref_root(leaf, dref);
1009 ret = add_indirect_ref(fs_info, preftrees, root,
1010 &key, 0, bytenr, count,
1020 ptr += btrfs_extent_inline_ref_size(type);
1027 * add all non-inline backrefs for bytenr to the list
1029 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
1031 static int add_keyed_refs(struct btrfs_fs_info *fs_info,
1032 struct btrfs_path *path, u64 bytenr,
1033 int info_level, struct preftrees *preftrees,
1034 struct share_check *sc)
1036 struct btrfs_root *extent_root = fs_info->extent_root;
1039 struct extent_buffer *leaf;
1040 struct btrfs_key key;
1043 ret = btrfs_next_item(extent_root, path);
1051 slot = path->slots[0];
1052 leaf = path->nodes[0];
1053 btrfs_item_key_to_cpu(leaf, &key, slot);
1055 if (key.objectid != bytenr)
1057 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1059 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1063 case BTRFS_SHARED_BLOCK_REF_KEY:
1064 /* SHARED DIRECT METADATA backref */
1065 ret = add_direct_ref(fs_info, preftrees,
1066 info_level + 1, key.offset,
1067 bytenr, 1, NULL, GFP_NOFS);
1069 case BTRFS_SHARED_DATA_REF_KEY: {
1070 /* SHARED DIRECT FULL backref */
1071 struct btrfs_shared_data_ref *sdref;
1074 sdref = btrfs_item_ptr(leaf, slot,
1075 struct btrfs_shared_data_ref);
1076 count = btrfs_shared_data_ref_count(leaf, sdref);
1077 ret = add_direct_ref(fs_info, preftrees, 0,
1078 key.offset, bytenr, count,
1082 case BTRFS_TREE_BLOCK_REF_KEY:
1083 /* NORMAL INDIRECT METADATA backref */
1084 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1085 NULL, info_level + 1, bytenr,
1088 case BTRFS_EXTENT_DATA_REF_KEY: {
1089 /* NORMAL INDIRECT DATA backref */
1090 struct btrfs_extent_data_ref *dref;
1094 dref = btrfs_item_ptr(leaf, slot,
1095 struct btrfs_extent_data_ref);
1096 count = btrfs_extent_data_ref_count(leaf, dref);
1097 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1099 key.type = BTRFS_EXTENT_DATA_KEY;
1100 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1102 if (sc && sc->inum && key.objectid != sc->inum &&
1103 !sc->have_delayed_delete_refs) {
1104 ret = BACKREF_FOUND_SHARED;
1108 root = btrfs_extent_data_ref_root(leaf, dref);
1109 ret = add_indirect_ref(fs_info, preftrees, root,
1110 &key, 0, bytenr, count,
1126 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1127 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1128 * indirect refs to their parent bytenr.
1129 * When roots are found, they're added to the roots list
1131 * If time_seq is set to SEQ_LAST, it will not search delayed_refs, and behave
1132 * much like trans == NULL case, the difference only lies in it will not
1134 * The special case is for qgroup to search roots in commit_transaction().
1136 * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a
1137 * shared extent is detected.
1139 * Otherwise this returns 0 for success and <0 for an error.
1141 * FIXME some caching might speed things up
1143 static int find_parent_nodes(struct btrfs_trans_handle *trans,
1144 struct btrfs_fs_info *fs_info, u64 bytenr,
1145 u64 time_seq, struct ulist *refs,
1146 struct ulist *roots, const u64 *extent_item_pos,
1147 struct share_check *sc)
1149 struct btrfs_key key;
1150 struct btrfs_path *path;
1151 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1152 struct btrfs_delayed_ref_head *head;
1155 struct prelim_ref *ref;
1156 struct rb_node *node;
1157 struct extent_inode_elem *eie = NULL;
1158 /* total of both direct AND indirect refs! */
1160 struct preftrees preftrees = {
1161 .direct = PREFTREE_INIT,
1162 .indirect = PREFTREE_INIT,
1163 .indirect_missing_keys = PREFTREE_INIT
1166 key.objectid = bytenr;
1167 key.offset = (u64)-1;
1168 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1169 key.type = BTRFS_METADATA_ITEM_KEY;
1171 key.type = BTRFS_EXTENT_ITEM_KEY;
1173 path = btrfs_alloc_path();
1177 path->search_commit_root = 1;
1178 path->skip_locking = 1;
1181 if (time_seq == SEQ_LAST)
1182 path->skip_locking = 1;
1185 * grab both a lock on the path and a lock on the delayed ref head.
1186 * We need both to get a consistent picture of how the refs look
1187 * at a specified point in time
1192 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
1196 /* This shouldn't happen, indicates a bug or fs corruption. */
1202 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1203 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1204 time_seq != SEQ_LAST) {
1206 if (trans && time_seq != SEQ_LAST) {
1209 * look if there are updates for this ref queued and lock the
1212 delayed_refs = &trans->transaction->delayed_refs;
1213 spin_lock(&delayed_refs->lock);
1214 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
1216 if (!mutex_trylock(&head->mutex)) {
1217 refcount_inc(&head->node.refs);
1218 spin_unlock(&delayed_refs->lock);
1220 btrfs_release_path(path);
1223 * Mutex was contended, block until it's
1224 * released and try again
1226 mutex_lock(&head->mutex);
1227 mutex_unlock(&head->mutex);
1228 btrfs_put_delayed_ref(&head->node);
1231 spin_unlock(&delayed_refs->lock);
1232 ret = add_delayed_refs(fs_info, head, time_seq,
1233 &preftrees, &total_refs, sc);
1234 mutex_unlock(&head->mutex);
1238 spin_unlock(&delayed_refs->lock);
1242 if (path->slots[0]) {
1243 struct extent_buffer *leaf;
1247 leaf = path->nodes[0];
1248 slot = path->slots[0];
1249 btrfs_item_key_to_cpu(leaf, &key, slot);
1250 if (key.objectid == bytenr &&
1251 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1252 key.type == BTRFS_METADATA_ITEM_KEY)) {
1253 ret = add_inline_refs(fs_info, path, bytenr,
1254 &info_level, &preftrees,
1258 ret = add_keyed_refs(fs_info, path, bytenr, info_level,
1265 btrfs_release_path(path);
1267 ret = add_missing_keys(fs_info, &preftrees, path->skip_locking == 0);
1271 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root));
1273 ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees,
1274 extent_item_pos, total_refs, sc);
1278 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root));
1281 * This walks the tree of merged and resolved refs. Tree blocks are
1282 * read in as needed. Unique entries are added to the ulist, and
1283 * the list of found roots is updated.
1285 * We release the entire tree in one go before returning.
1287 node = rb_first(&preftrees.direct.root);
1289 ref = rb_entry(node, struct prelim_ref, rbnode);
1290 node = rb_next(&ref->rbnode);
1292 * ref->count < 0 can happen here if there are delayed
1293 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1294 * prelim_ref_insert() relies on this when merging
1295 * identical refs to keep the overall count correct.
1296 * prelim_ref_insert() will merge only those refs
1297 * which compare identically. Any refs having
1298 * e.g. different offsets would not be merged,
1299 * and would retain their original ref->count < 0.
1301 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1302 if (sc && sc->root_objectid &&
1303 ref->root_id != sc->root_objectid) {
1304 ret = BACKREF_FOUND_SHARED;
1308 /* no parent == root of tree */
1309 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1313 if (ref->count && ref->parent) {
1314 if (extent_item_pos && !ref->inode_list &&
1316 struct extent_buffer *eb;
1318 eb = read_tree_block(fs_info, ref->parent, 0);
1322 } else if (!extent_buffer_uptodate(eb)) {
1323 free_extent_buffer(eb);
1327 if (!path->skip_locking) {
1328 btrfs_tree_read_lock(eb);
1329 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1331 ret = find_extent_in_eb(eb, bytenr,
1332 *extent_item_pos, &eie);
1333 if (!path->skip_locking)
1334 btrfs_tree_read_unlock_blocking(eb);
1335 free_extent_buffer(eb);
1338 ref->inode_list = eie;
1340 ret = ulist_add_merge_ptr(refs, ref->parent,
1342 (void **)&eie, GFP_NOFS);
1345 if (!ret && extent_item_pos) {
1347 * We've recorded that parent, so we must extend
1348 * its inode list here.
1350 * However if there was corruption we may not
1351 * have found an eie, return an error in this
1361 eie->next = ref->inode_list;
1369 btrfs_free_path(path);
1371 prelim_release(&preftrees.direct);
1372 prelim_release(&preftrees.indirect);
1373 prelim_release(&preftrees.indirect_missing_keys);
1376 free_inode_elem_list(eie);
1381 * Finds all leafs with a reference to the specified combination of bytenr and
1382 * offset. key_list_head will point to a list of corresponding keys (caller must
1383 * free each list element). The leafs will be stored in the leafs ulist, which
1384 * must be freed with ulist_free.
1386 * returns 0 on success, <0 on error
1388 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1389 struct btrfs_fs_info *fs_info, u64 bytenr,
1390 u64 time_seq, struct ulist **leafs,
1391 const u64 *extent_item_pos)
1395 *leafs = ulist_alloc(GFP_NOFS);
1399 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1400 *leafs, NULL, extent_item_pos, NULL);
1401 if (ret < 0 && ret != -ENOENT) {
1402 free_leaf_list(*leafs);
1410 * walk all backrefs for a given extent to find all roots that reference this
1411 * extent. Walking a backref means finding all extents that reference this
1412 * extent and in turn walk the backrefs of those, too. Naturally this is a
1413 * recursive process, but here it is implemented in an iterative fashion: We
1414 * find all referencing extents for the extent in question and put them on a
1415 * list. In turn, we find all referencing extents for those, further appending
1416 * to the list. The way we iterate the list allows adding more elements after
1417 * the current while iterating. The process stops when we reach the end of the
1418 * list. Found roots are added to the roots list.
1420 * returns 0 on success, < 0 on error.
1422 static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
1423 struct btrfs_fs_info *fs_info, u64 bytenr,
1424 u64 time_seq, struct ulist **roots)
1427 struct ulist_node *node = NULL;
1428 struct ulist_iterator uiter;
1431 tmp = ulist_alloc(GFP_NOFS);
1434 *roots = ulist_alloc(GFP_NOFS);
1440 ULIST_ITER_INIT(&uiter);
1442 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1443 tmp, *roots, NULL, NULL);
1444 if (ret < 0 && ret != -ENOENT) {
1450 node = ulist_next(tmp, &uiter);
1461 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1462 struct btrfs_fs_info *fs_info, u64 bytenr,
1463 u64 time_seq, struct ulist **roots)
1468 down_read(&fs_info->commit_root_sem);
1469 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr,
1472 up_read(&fs_info->commit_root_sem);
1477 * btrfs_check_shared - tell us whether an extent is shared
1479 * btrfs_check_shared uses the backref walking code but will short
1480 * circuit as soon as it finds a root or inode that doesn't match the
1481 * one passed in. This provides a significant performance benefit for
1482 * callers (such as fiemap) which want to know whether the extent is
1483 * shared but do not need a ref count.
1485 * This attempts to attach to the running transaction in order to account for
1486 * delayed refs, but continues on even when no running transaction exists.
1488 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1490 int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
1492 struct btrfs_fs_info *fs_info = root->fs_info;
1493 struct btrfs_trans_handle *trans;
1494 struct ulist *tmp = NULL;
1495 struct ulist *roots = NULL;
1496 struct ulist_iterator uiter;
1497 struct ulist_node *node;
1498 struct seq_list elem = SEQ_LIST_INIT(elem);
1500 struct share_check shared = {
1501 .root_objectid = root->objectid,
1504 .have_delayed_delete_refs = false,
1507 tmp = ulist_alloc(GFP_NOFS);
1508 roots = ulist_alloc(GFP_NOFS);
1509 if (!tmp || !roots) {
1514 trans = btrfs_attach_transaction(root);
1515 if (IS_ERR(trans)) {
1516 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
1517 ret = PTR_ERR(trans);
1521 down_read(&fs_info->commit_root_sem);
1523 btrfs_get_tree_mod_seq(fs_info, &elem);
1526 ULIST_ITER_INIT(&uiter);
1528 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1529 roots, NULL, &shared);
1530 if (ret == BACKREF_FOUND_SHARED) {
1531 /* this is the only condition under which we return 1 */
1535 if (ret < 0 && ret != -ENOENT)
1538 node = ulist_next(tmp, &uiter);
1542 shared.share_count = 0;
1543 shared.have_delayed_delete_refs = false;
1548 btrfs_put_tree_mod_seq(fs_info, &elem);
1549 btrfs_end_transaction(trans);
1551 up_read(&fs_info->commit_root_sem);
1559 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1560 u64 start_off, struct btrfs_path *path,
1561 struct btrfs_inode_extref **ret_extref,
1565 struct btrfs_key key;
1566 struct btrfs_key found_key;
1567 struct btrfs_inode_extref *extref;
1568 const struct extent_buffer *leaf;
1571 key.objectid = inode_objectid;
1572 key.type = BTRFS_INODE_EXTREF_KEY;
1573 key.offset = start_off;
1575 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1580 leaf = path->nodes[0];
1581 slot = path->slots[0];
1582 if (slot >= btrfs_header_nritems(leaf)) {
1584 * If the item at offset is not found,
1585 * btrfs_search_slot will point us to the slot
1586 * where it should be inserted. In our case
1587 * that will be the slot directly before the
1588 * next INODE_REF_KEY_V2 item. In the case
1589 * that we're pointing to the last slot in a
1590 * leaf, we must move one leaf over.
1592 ret = btrfs_next_leaf(root, path);
1601 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1604 * Check that we're still looking at an extended ref key for
1605 * this particular objectid. If we have different
1606 * objectid or type then there are no more to be found
1607 * in the tree and we can exit.
1610 if (found_key.objectid != inode_objectid)
1612 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1616 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1617 extref = (struct btrfs_inode_extref *)ptr;
1618 *ret_extref = extref;
1620 *found_off = found_key.offset;
1628 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1629 * Elements of the path are separated by '/' and the path is guaranteed to be
1630 * 0-terminated. the path is only given within the current file system.
1631 * Therefore, it never starts with a '/'. the caller is responsible to provide
1632 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1633 * the start point of the resulting string is returned. this pointer is within
1635 * in case the path buffer would overflow, the pointer is decremented further
1636 * as if output was written to the buffer, though no more output is actually
1637 * generated. that way, the caller can determine how much space would be
1638 * required for the path to fit into the buffer. in that case, the returned
1639 * value will be smaller than dest. callers must check this!
1641 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1642 u32 name_len, unsigned long name_off,
1643 struct extent_buffer *eb_in, u64 parent,
1644 char *dest, u32 size)
1649 s64 bytes_left = ((s64)size) - 1;
1650 struct extent_buffer *eb = eb_in;
1651 struct btrfs_key found_key;
1652 int leave_spinning = path->leave_spinning;
1653 struct btrfs_inode_ref *iref;
1655 if (bytes_left >= 0)
1656 dest[bytes_left] = '\0';
1658 path->leave_spinning = 1;
1660 bytes_left -= name_len;
1661 if (bytes_left >= 0)
1662 read_extent_buffer(eb, dest + bytes_left,
1663 name_off, name_len);
1665 if (!path->skip_locking)
1666 btrfs_tree_read_unlock_blocking(eb);
1667 free_extent_buffer(eb);
1669 ret = btrfs_find_item(fs_root, path, parent, 0,
1670 BTRFS_INODE_REF_KEY, &found_key);
1676 next_inum = found_key.offset;
1678 /* regular exit ahead */
1679 if (parent == next_inum)
1682 slot = path->slots[0];
1683 eb = path->nodes[0];
1684 /* make sure we can use eb after releasing the path */
1686 if (!path->skip_locking)
1687 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1688 path->nodes[0] = NULL;
1691 btrfs_release_path(path);
1692 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1694 name_len = btrfs_inode_ref_name_len(eb, iref);
1695 name_off = (unsigned long)(iref + 1);
1699 if (bytes_left >= 0)
1700 dest[bytes_left] = '/';
1703 btrfs_release_path(path);
1704 path->leave_spinning = leave_spinning;
1707 return ERR_PTR(ret);
1709 return dest + bytes_left;
1713 * this makes the path point to (logical EXTENT_ITEM *)
1714 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1715 * tree blocks and <0 on error.
1717 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1718 struct btrfs_path *path, struct btrfs_key *found_key,
1725 const struct extent_buffer *eb;
1726 struct btrfs_extent_item *ei;
1727 struct btrfs_key key;
1729 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1730 key.type = BTRFS_METADATA_ITEM_KEY;
1732 key.type = BTRFS_EXTENT_ITEM_KEY;
1733 key.objectid = logical;
1734 key.offset = (u64)-1;
1736 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1740 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1746 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1747 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1748 size = fs_info->nodesize;
1749 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1750 size = found_key->offset;
1752 if (found_key->objectid > logical ||
1753 found_key->objectid + size <= logical) {
1754 btrfs_debug(fs_info,
1755 "logical %llu is not within any extent", logical);
1759 eb = path->nodes[0];
1760 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1761 BUG_ON(item_size < sizeof(*ei));
1763 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1764 flags = btrfs_extent_flags(eb, ei);
1766 btrfs_debug(fs_info,
1767 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1768 logical, logical - found_key->objectid, found_key->objectid,
1769 found_key->offset, flags, item_size);
1771 WARN_ON(!flags_ret);
1773 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1774 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1775 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1776 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1786 * helper function to iterate extent inline refs. ptr must point to a 0 value
1787 * for the first call and may be modified. it is used to track state.
1788 * if more refs exist, 0 is returned and the next call to
1789 * get_extent_inline_ref must pass the modified ptr parameter to get the
1790 * next ref. after the last ref was processed, 1 is returned.
1791 * returns <0 on error
1793 static int get_extent_inline_ref(unsigned long *ptr,
1794 const struct extent_buffer *eb,
1795 const struct btrfs_key *key,
1796 const struct btrfs_extent_item *ei,
1798 struct btrfs_extent_inline_ref **out_eiref,
1803 struct btrfs_tree_block_info *info;
1807 flags = btrfs_extent_flags(eb, ei);
1808 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1809 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1810 /* a skinny metadata extent */
1812 (struct btrfs_extent_inline_ref *)(ei + 1);
1814 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1815 info = (struct btrfs_tree_block_info *)(ei + 1);
1817 (struct btrfs_extent_inline_ref *)(info + 1);
1820 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1822 *ptr = (unsigned long)*out_eiref;
1823 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1827 end = (unsigned long)ei + item_size;
1828 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1829 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
1830 BTRFS_REF_TYPE_ANY);
1831 if (*out_type == BTRFS_REF_TYPE_INVALID)
1834 *ptr += btrfs_extent_inline_ref_size(*out_type);
1835 WARN_ON(*ptr > end);
1837 return 1; /* last */
1843 * reads the tree block backref for an extent. tree level and root are returned
1844 * through out_level and out_root. ptr must point to a 0 value for the first
1845 * call and may be modified (see get_extent_inline_ref comment).
1846 * returns 0 if data was provided, 1 if there was no more data to provide or
1849 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1850 struct btrfs_key *key, struct btrfs_extent_item *ei,
1851 u32 item_size, u64 *out_root, u8 *out_level)
1855 struct btrfs_extent_inline_ref *eiref;
1857 if (*ptr == (unsigned long)-1)
1861 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
1866 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1867 type == BTRFS_SHARED_BLOCK_REF_KEY)
1874 /* we can treat both ref types equally here */
1875 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1877 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1878 struct btrfs_tree_block_info *info;
1880 info = (struct btrfs_tree_block_info *)(ei + 1);
1881 *out_level = btrfs_tree_block_level(eb, info);
1883 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1884 *out_level = (u8)key->offset;
1888 *ptr = (unsigned long)-1;
1893 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1894 struct extent_inode_elem *inode_list,
1895 u64 root, u64 extent_item_objectid,
1896 iterate_extent_inodes_t *iterate, void *ctx)
1898 struct extent_inode_elem *eie;
1901 for (eie = inode_list; eie; eie = eie->next) {
1902 btrfs_debug(fs_info,
1903 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1904 extent_item_objectid, eie->inum,
1906 ret = iterate(eie->inum, eie->offset, root, ctx);
1908 btrfs_debug(fs_info,
1909 "stopping iteration for %llu due to ret=%d",
1910 extent_item_objectid, ret);
1919 * calls iterate() for every inode that references the extent identified by
1920 * the given parameters.
1921 * when the iterator function returns a non-zero value, iteration stops.
1923 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1924 u64 extent_item_objectid, u64 extent_item_pos,
1925 int search_commit_root,
1926 iterate_extent_inodes_t *iterate, void *ctx)
1929 struct btrfs_trans_handle *trans = NULL;
1930 struct ulist *refs = NULL;
1931 struct ulist *roots = NULL;
1932 struct ulist_node *ref_node = NULL;
1933 struct ulist_node *root_node = NULL;
1934 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
1935 struct ulist_iterator ref_uiter;
1936 struct ulist_iterator root_uiter;
1938 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
1939 extent_item_objectid);
1941 if (!search_commit_root) {
1942 trans = btrfs_attach_transaction(fs_info->extent_root);
1943 if (IS_ERR(trans)) {
1944 if (PTR_ERR(trans) != -ENOENT &&
1945 PTR_ERR(trans) != -EROFS)
1946 return PTR_ERR(trans);
1952 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1954 down_read(&fs_info->commit_root_sem);
1956 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1957 tree_mod_seq_elem.seq, &refs,
1962 ULIST_ITER_INIT(&ref_uiter);
1963 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1964 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val,
1965 tree_mod_seq_elem.seq, &roots);
1968 ULIST_ITER_INIT(&root_uiter);
1969 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1970 btrfs_debug(fs_info,
1971 "root %llu references leaf %llu, data list %#llx",
1972 root_node->val, ref_node->val,
1974 ret = iterate_leaf_refs(fs_info,
1975 (struct extent_inode_elem *)
1976 (uintptr_t)ref_node->aux,
1978 extent_item_objectid,
1984 free_leaf_list(refs);
1987 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1988 btrfs_end_transaction(trans);
1990 up_read(&fs_info->commit_root_sem);
1996 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1997 struct btrfs_path *path,
1998 iterate_extent_inodes_t *iterate, void *ctx)
2001 u64 extent_item_pos;
2003 struct btrfs_key found_key;
2004 int search_commit_root = path->search_commit_root;
2006 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
2007 btrfs_release_path(path);
2010 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2013 extent_item_pos = logical - found_key.objectid;
2014 ret = iterate_extent_inodes(fs_info, found_key.objectid,
2015 extent_item_pos, search_commit_root,
2021 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
2022 struct extent_buffer *eb, void *ctx);
2024 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
2025 struct btrfs_path *path,
2026 iterate_irefs_t *iterate, void *ctx)
2035 struct extent_buffer *eb;
2036 struct btrfs_item *item;
2037 struct btrfs_inode_ref *iref;
2038 struct btrfs_key found_key;
2041 ret = btrfs_find_item(fs_root, path, inum,
2042 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2048 ret = found ? 0 : -ENOENT;
2053 parent = found_key.offset;
2054 slot = path->slots[0];
2055 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2060 extent_buffer_get(eb);
2061 btrfs_tree_read_lock(eb);
2062 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2063 btrfs_release_path(path);
2065 item = btrfs_item_nr(slot);
2066 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2068 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
2069 name_len = btrfs_inode_ref_name_len(eb, iref);
2070 /* path must be released before calling iterate()! */
2071 btrfs_debug(fs_root->fs_info,
2072 "following ref at offset %u for inode %llu in tree %llu",
2073 cur, found_key.objectid, fs_root->objectid);
2074 ret = iterate(parent, name_len,
2075 (unsigned long)(iref + 1), eb, ctx);
2078 len = sizeof(*iref) + name_len;
2079 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2081 btrfs_tree_read_unlock_blocking(eb);
2082 free_extent_buffer(eb);
2085 btrfs_release_path(path);
2090 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
2091 struct btrfs_path *path,
2092 iterate_irefs_t *iterate, void *ctx)
2099 struct extent_buffer *eb;
2100 struct btrfs_inode_extref *extref;
2106 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2111 ret = found ? 0 : -ENOENT;
2116 slot = path->slots[0];
2117 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2122 extent_buffer_get(eb);
2124 btrfs_tree_read_lock(eb);
2125 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2126 btrfs_release_path(path);
2128 item_size = btrfs_item_size_nr(eb, slot);
2129 ptr = btrfs_item_ptr_offset(eb, slot);
2132 while (cur_offset < item_size) {
2135 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2136 parent = btrfs_inode_extref_parent(eb, extref);
2137 name_len = btrfs_inode_extref_name_len(eb, extref);
2138 ret = iterate(parent, name_len,
2139 (unsigned long)&extref->name, eb, ctx);
2143 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2144 cur_offset += sizeof(*extref);
2146 btrfs_tree_read_unlock_blocking(eb);
2147 free_extent_buffer(eb);
2152 btrfs_release_path(path);
2157 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
2158 struct btrfs_path *path, iterate_irefs_t *iterate,
2164 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
2167 else if (ret != -ENOENT)
2170 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
2171 if (ret == -ENOENT && found_refs)
2178 * returns 0 if the path could be dumped (probably truncated)
2179 * returns <0 in case of an error
2181 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2182 struct extent_buffer *eb, void *ctx)
2184 struct inode_fs_paths *ipath = ctx;
2187 int i = ipath->fspath->elem_cnt;
2188 const int s_ptr = sizeof(char *);
2191 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2192 ipath->fspath->bytes_left - s_ptr : 0;
2194 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2195 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2196 name_off, eb, inum, fspath_min, bytes_left);
2198 return PTR_ERR(fspath);
2200 if (fspath > fspath_min) {
2201 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2202 ++ipath->fspath->elem_cnt;
2203 ipath->fspath->bytes_left = fspath - fspath_min;
2205 ++ipath->fspath->elem_missed;
2206 ipath->fspath->bytes_missing += fspath_min - fspath;
2207 ipath->fspath->bytes_left = 0;
2214 * this dumps all file system paths to the inode into the ipath struct, provided
2215 * is has been created large enough. each path is zero-terminated and accessed
2216 * from ipath->fspath->val[i].
2217 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2218 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2219 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2220 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2221 * have been needed to return all paths.
2223 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2225 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
2226 inode_to_path, ipath);
2229 struct btrfs_data_container *init_data_container(u32 total_bytes)
2231 struct btrfs_data_container *data;
2234 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2235 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2237 return ERR_PTR(-ENOMEM);
2239 if (total_bytes >= sizeof(*data)) {
2240 data->bytes_left = total_bytes - sizeof(*data);
2241 data->bytes_missing = 0;
2243 data->bytes_missing = sizeof(*data) - total_bytes;
2244 data->bytes_left = 0;
2248 data->elem_missed = 0;
2254 * allocates space to return multiple file system paths for an inode.
2255 * total_bytes to allocate are passed, note that space usable for actual path
2256 * information will be total_bytes - sizeof(struct inode_fs_paths).
2257 * the returned pointer must be freed with free_ipath() in the end.
2259 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2260 struct btrfs_path *path)
2262 struct inode_fs_paths *ifp;
2263 struct btrfs_data_container *fspath;
2265 fspath = init_data_container(total_bytes);
2267 return (void *)fspath;
2269 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2272 return ERR_PTR(-ENOMEM);
2275 ifp->btrfs_path = path;
2276 ifp->fspath = fspath;
2277 ifp->fs_root = fs_root;
2282 void free_ipath(struct inode_fs_paths *ipath)
2286 kvfree(ipath->fspath);