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.
19 #include <linux/vmalloc.h>
24 #include "transaction.h"
25 #include "delayed-ref.h"
28 struct extent_inode_elem {
31 struct extent_inode_elem *next;
34 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
35 struct btrfs_file_extent_item *fi,
37 struct extent_inode_elem **eie)
40 struct extent_inode_elem *e;
42 if (!btrfs_file_extent_compression(eb, fi) &&
43 !btrfs_file_extent_encryption(eb, fi) &&
44 !btrfs_file_extent_other_encoding(eb, fi)) {
48 data_offset = btrfs_file_extent_offset(eb, fi);
49 data_len = btrfs_file_extent_num_bytes(eb, fi);
51 if (extent_item_pos < data_offset ||
52 extent_item_pos >= data_offset + data_len)
54 offset = extent_item_pos - data_offset;
57 e = kmalloc(sizeof(*e), GFP_NOFS);
62 e->inum = key->objectid;
63 e->offset = key->offset + offset;
69 static void free_inode_elem_list(struct extent_inode_elem *eie)
71 struct extent_inode_elem *eie_next;
73 for (; eie; eie = eie_next) {
79 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
81 struct extent_inode_elem **eie)
85 struct btrfs_file_extent_item *fi;
92 * from the shared data ref, we only have the leaf but we need
93 * the key. thus, we must look into all items and see that we
94 * find one (some) with a reference to our extent item.
96 nritems = btrfs_header_nritems(eb);
97 for (slot = 0; slot < nritems; ++slot) {
98 btrfs_item_key_to_cpu(eb, &key, slot);
99 if (key.type != BTRFS_EXTENT_DATA_KEY)
101 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
102 extent_type = btrfs_file_extent_type(eb, fi);
103 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
105 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
106 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
107 if (disk_byte != wanted_disk_byte)
110 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
119 * this structure records all encountered refs on the way up to the root
121 struct __prelim_ref {
122 struct list_head list;
124 struct btrfs_key key_for_search;
127 struct extent_inode_elem *inode_list;
129 u64 wanted_disk_byte;
132 static struct kmem_cache *btrfs_prelim_ref_cache;
134 int __init btrfs_prelim_ref_init(void)
136 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
137 sizeof(struct __prelim_ref),
139 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
141 if (!btrfs_prelim_ref_cache)
146 void btrfs_prelim_ref_exit(void)
148 if (btrfs_prelim_ref_cache)
149 kmem_cache_destroy(btrfs_prelim_ref_cache);
153 * the rules for all callers of this function are:
154 * - obtaining the parent is the goal
155 * - if you add a key, you must know that it is a correct key
156 * - if you cannot add the parent or a correct key, then we will look into the
157 * block later to set a correct key
161 * backref type | shared | indirect | shared | indirect
162 * information | tree | tree | data | data
163 * --------------------+--------+----------+--------+----------
164 * parent logical | y | - | - | -
165 * key to resolve | - | y | y | y
166 * tree block logical | - | - | - | -
167 * root for resolving | y | y | y | y
169 * - column 1: we've the parent -> done
170 * - column 2, 3, 4: we use the key to find the parent
172 * on disk refs (inline or keyed)
173 * ==============================
174 * backref type | shared | indirect | shared | indirect
175 * information | tree | tree | data | data
176 * --------------------+--------+----------+--------+----------
177 * parent logical | y | - | y | -
178 * key to resolve | - | - | - | y
179 * tree block logical | y | y | y | y
180 * root for resolving | - | y | y | y
182 * - column 1, 3: we've the parent -> done
183 * - column 2: we take the first key from the block to find the parent
184 * (see __add_missing_keys)
185 * - column 4: we use the key to find the parent
187 * additional information that's available but not required to find the parent
188 * block might help in merging entries to gain some speed.
191 static int __add_prelim_ref(struct list_head *head, u64 root_id,
192 struct btrfs_key *key, int level,
193 u64 parent, u64 wanted_disk_byte, int count,
196 struct __prelim_ref *ref;
198 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
201 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
205 ref->root_id = root_id;
207 ref->key_for_search = *key;
209 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
211 ref->inode_list = NULL;
214 ref->parent = parent;
215 ref->wanted_disk_byte = wanted_disk_byte;
216 list_add_tail(&ref->list, head);
221 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
222 struct ulist *parents, struct __prelim_ref *ref,
223 int level, u64 time_seq, const u64 *extent_item_pos,
228 struct extent_buffer *eb;
229 struct btrfs_key key;
230 struct btrfs_key *key_for_search = &ref->key_for_search;
231 struct btrfs_file_extent_item *fi;
232 struct extent_inode_elem *eie = NULL, *old = NULL;
234 u64 wanted_disk_byte = ref->wanted_disk_byte;
238 eb = path->nodes[level];
239 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
246 * We normally enter this function with the path already pointing to
247 * the first item to check. But sometimes, we may enter it with
248 * slot==nritems. In that case, go to the next leaf before we continue.
250 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
251 ret = btrfs_next_old_leaf(root, path, time_seq);
253 while (!ret && count < total_refs) {
255 slot = path->slots[0];
257 btrfs_item_key_to_cpu(eb, &key, slot);
259 if (key.objectid != key_for_search->objectid ||
260 key.type != BTRFS_EXTENT_DATA_KEY)
263 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
264 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
266 if (disk_byte == wanted_disk_byte) {
270 if (extent_item_pos) {
271 ret = check_extent_in_eb(&key, eb, fi,
279 ret = ulist_add_merge(parents, eb->start,
281 (u64 *)&old, GFP_NOFS);
284 if (!ret && extent_item_pos) {
292 ret = btrfs_next_old_item(root, path, time_seq);
298 free_inode_elem_list(eie);
303 * resolve an indirect backref in the form (root_id, key, level)
304 * to a logical address
306 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
307 struct btrfs_path *path, u64 time_seq,
308 struct __prelim_ref *ref,
309 struct ulist *parents,
310 const u64 *extent_item_pos, u64 total_refs)
312 struct btrfs_root *root;
313 struct btrfs_key root_key;
314 struct extent_buffer *eb;
317 int level = ref->level;
320 root_key.objectid = ref->root_id;
321 root_key.type = BTRFS_ROOT_ITEM_KEY;
322 root_key.offset = (u64)-1;
324 index = srcu_read_lock(&fs_info->subvol_srcu);
326 root = btrfs_read_fs_root_no_name(fs_info, &root_key);
328 srcu_read_unlock(&fs_info->subvol_srcu, index);
333 if (path->search_commit_root)
334 root_level = btrfs_header_level(root->commit_root);
336 root_level = btrfs_old_root_level(root, time_seq);
338 if (root_level + 1 == level) {
339 srcu_read_unlock(&fs_info->subvol_srcu, index);
343 path->lowest_level = level;
344 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
346 /* root node has been locked, we can release @subvol_srcu safely here */
347 srcu_read_unlock(&fs_info->subvol_srcu, index);
349 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
350 "%d for key (%llu %u %llu)\n",
351 ref->root_id, level, ref->count, ret,
352 ref->key_for_search.objectid, ref->key_for_search.type,
353 ref->key_for_search.offset);
357 eb = path->nodes[level];
359 if (WARN_ON(!level)) {
364 eb = path->nodes[level];
367 ret = add_all_parents(root, path, parents, ref, level, time_seq,
368 extent_item_pos, total_refs);
370 path->lowest_level = 0;
371 btrfs_release_path(path);
376 * resolve all indirect backrefs from the list
378 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
379 struct btrfs_path *path, u64 time_seq,
380 struct list_head *head,
381 const u64 *extent_item_pos, u64 total_refs)
385 struct __prelim_ref *ref;
386 struct __prelim_ref *ref_safe;
387 struct __prelim_ref *new_ref;
388 struct ulist *parents;
389 struct ulist_node *node;
390 struct ulist_iterator uiter;
392 parents = ulist_alloc(GFP_NOFS);
397 * _safe allows us to insert directly after the current item without
398 * iterating over the newly inserted items.
399 * we're also allowed to re-assign ref during iteration.
401 list_for_each_entry_safe(ref, ref_safe, head, list) {
402 if (ref->parent) /* already direct */
406 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
407 parents, extent_item_pos,
410 * we can only tolerate ENOENT,otherwise,we should catch error
411 * and return directly.
413 if (err == -ENOENT) {
420 /* we put the first parent into the ref at hand */
421 ULIST_ITER_INIT(&uiter);
422 node = ulist_next(parents, &uiter);
423 ref->parent = node ? node->val : 0;
424 ref->inode_list = node ?
425 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
427 /* additional parents require new refs being added here */
428 while ((node = ulist_next(parents, &uiter))) {
429 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
435 memcpy(new_ref, ref, sizeof(*ref));
436 new_ref->parent = node->val;
437 new_ref->inode_list = (struct extent_inode_elem *)
438 (uintptr_t)node->aux;
439 list_add(&new_ref->list, &ref->list);
441 ulist_reinit(parents);
448 static inline int ref_for_same_block(struct __prelim_ref *ref1,
449 struct __prelim_ref *ref2)
451 if (ref1->level != ref2->level)
453 if (ref1->root_id != ref2->root_id)
455 if (ref1->key_for_search.type != ref2->key_for_search.type)
457 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
459 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
461 if (ref1->parent != ref2->parent)
468 * read tree blocks and add keys where required.
470 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
471 struct list_head *head)
473 struct list_head *pos;
474 struct extent_buffer *eb;
476 list_for_each(pos, head) {
477 struct __prelim_ref *ref;
478 ref = list_entry(pos, struct __prelim_ref, list);
482 if (ref->key_for_search.type)
484 BUG_ON(!ref->wanted_disk_byte);
485 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
486 fs_info->tree_root->leafsize, 0);
487 if (!eb || !extent_buffer_uptodate(eb)) {
488 free_extent_buffer(eb);
491 btrfs_tree_read_lock(eb);
492 if (btrfs_header_level(eb) == 0)
493 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
495 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
496 btrfs_tree_read_unlock(eb);
497 free_extent_buffer(eb);
503 * merge two lists of backrefs and adjust counts accordingly
505 * mode = 1: merge identical keys, if key is set
506 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
507 * additionally, we could even add a key range for the blocks we
508 * looked into to merge even more (-> replace unresolved refs by those
510 * mode = 2: merge identical parents
512 static void __merge_refs(struct list_head *head, int mode)
514 struct list_head *pos1;
516 list_for_each(pos1, head) {
517 struct list_head *n2;
518 struct list_head *pos2;
519 struct __prelim_ref *ref1;
521 ref1 = list_entry(pos1, struct __prelim_ref, list);
523 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
524 pos2 = n2, n2 = pos2->next) {
525 struct __prelim_ref *ref2;
526 struct __prelim_ref *xchg;
527 struct extent_inode_elem *eie;
529 ref2 = list_entry(pos2, struct __prelim_ref, list);
532 if (!ref_for_same_block(ref1, ref2))
534 if (!ref1->parent && ref2->parent) {
540 if (ref1->parent != ref2->parent)
544 eie = ref1->inode_list;
545 while (eie && eie->next)
548 eie->next = ref2->inode_list;
550 ref1->inode_list = ref2->inode_list;
551 ref1->count += ref2->count;
553 list_del(&ref2->list);
554 kmem_cache_free(btrfs_prelim_ref_cache, ref2);
561 * add all currently queued delayed refs from this head whose seq nr is
562 * smaller or equal that seq to the list
564 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
565 struct list_head *prefs, u64 *total_refs)
567 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
568 struct rb_node *n = &head->node.rb_node;
569 struct btrfs_key key;
570 struct btrfs_key op_key = {0};
574 if (extent_op && extent_op->update_key)
575 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
577 spin_lock(&head->lock);
578 n = rb_first(&head->ref_root);
580 struct btrfs_delayed_ref_node *node;
581 node = rb_entry(n, struct btrfs_delayed_ref_node,
587 switch (node->action) {
588 case BTRFS_ADD_DELAYED_EXTENT:
589 case BTRFS_UPDATE_DELAYED_HEAD:
592 case BTRFS_ADD_DELAYED_REF:
595 case BTRFS_DROP_DELAYED_REF:
601 *total_refs += (node->ref_mod * sgn);
602 switch (node->type) {
603 case BTRFS_TREE_BLOCK_REF_KEY: {
604 struct btrfs_delayed_tree_ref *ref;
606 ref = btrfs_delayed_node_to_tree_ref(node);
607 ret = __add_prelim_ref(prefs, ref->root, &op_key,
608 ref->level + 1, 0, node->bytenr,
609 node->ref_mod * sgn, GFP_ATOMIC);
612 case BTRFS_SHARED_BLOCK_REF_KEY: {
613 struct btrfs_delayed_tree_ref *ref;
615 ref = btrfs_delayed_node_to_tree_ref(node);
616 ret = __add_prelim_ref(prefs, ref->root, NULL,
617 ref->level + 1, ref->parent,
619 node->ref_mod * sgn, GFP_ATOMIC);
622 case BTRFS_EXTENT_DATA_REF_KEY: {
623 struct btrfs_delayed_data_ref *ref;
624 ref = btrfs_delayed_node_to_data_ref(node);
626 key.objectid = ref->objectid;
627 key.type = BTRFS_EXTENT_DATA_KEY;
628 key.offset = ref->offset;
629 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
631 node->ref_mod * sgn, GFP_ATOMIC);
634 case BTRFS_SHARED_DATA_REF_KEY: {
635 struct btrfs_delayed_data_ref *ref;
637 ref = btrfs_delayed_node_to_data_ref(node);
639 key.objectid = ref->objectid;
640 key.type = BTRFS_EXTENT_DATA_KEY;
641 key.offset = ref->offset;
642 ret = __add_prelim_ref(prefs, ref->root, &key, 0,
643 ref->parent, node->bytenr,
644 node->ref_mod * sgn, GFP_ATOMIC);
653 spin_unlock(&head->lock);
658 * add all inline backrefs for bytenr to the list
660 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
661 struct btrfs_path *path, u64 bytenr,
662 int *info_level, struct list_head *prefs,
667 struct extent_buffer *leaf;
668 struct btrfs_key key;
669 struct btrfs_key found_key;
672 struct btrfs_extent_item *ei;
677 * enumerate all inline refs
679 leaf = path->nodes[0];
680 slot = path->slots[0];
682 item_size = btrfs_item_size_nr(leaf, slot);
683 BUG_ON(item_size < sizeof(*ei));
685 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
686 flags = btrfs_extent_flags(leaf, ei);
687 *total_refs += btrfs_extent_refs(leaf, ei);
688 btrfs_item_key_to_cpu(leaf, &found_key, slot);
690 ptr = (unsigned long)(ei + 1);
691 end = (unsigned long)ei + item_size;
693 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
694 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
695 struct btrfs_tree_block_info *info;
697 info = (struct btrfs_tree_block_info *)ptr;
698 *info_level = btrfs_tree_block_level(leaf, info);
699 ptr += sizeof(struct btrfs_tree_block_info);
701 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
702 *info_level = found_key.offset;
704 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
708 struct btrfs_extent_inline_ref *iref;
712 iref = (struct btrfs_extent_inline_ref *)ptr;
713 type = btrfs_extent_inline_ref_type(leaf, iref);
714 offset = btrfs_extent_inline_ref_offset(leaf, iref);
717 case BTRFS_SHARED_BLOCK_REF_KEY:
718 ret = __add_prelim_ref(prefs, 0, NULL,
719 *info_level + 1, offset,
720 bytenr, 1, GFP_NOFS);
722 case BTRFS_SHARED_DATA_REF_KEY: {
723 struct btrfs_shared_data_ref *sdref;
726 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
727 count = btrfs_shared_data_ref_count(leaf, sdref);
728 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
729 bytenr, count, GFP_NOFS);
732 case BTRFS_TREE_BLOCK_REF_KEY:
733 ret = __add_prelim_ref(prefs, offset, NULL,
735 bytenr, 1, GFP_NOFS);
737 case BTRFS_EXTENT_DATA_REF_KEY: {
738 struct btrfs_extent_data_ref *dref;
742 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
743 count = btrfs_extent_data_ref_count(leaf, dref);
744 key.objectid = btrfs_extent_data_ref_objectid(leaf,
746 key.type = BTRFS_EXTENT_DATA_KEY;
747 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
748 root = btrfs_extent_data_ref_root(leaf, dref);
749 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
750 bytenr, count, GFP_NOFS);
758 ptr += btrfs_extent_inline_ref_size(type);
765 * add all non-inline backrefs for bytenr to the list
767 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
768 struct btrfs_path *path, u64 bytenr,
769 int info_level, struct list_head *prefs)
771 struct btrfs_root *extent_root = fs_info->extent_root;
774 struct extent_buffer *leaf;
775 struct btrfs_key key;
778 ret = btrfs_next_item(extent_root, path);
786 slot = path->slots[0];
787 leaf = path->nodes[0];
788 btrfs_item_key_to_cpu(leaf, &key, slot);
790 if (key.objectid != bytenr)
792 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
794 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
798 case BTRFS_SHARED_BLOCK_REF_KEY:
799 ret = __add_prelim_ref(prefs, 0, NULL,
800 info_level + 1, key.offset,
801 bytenr, 1, GFP_NOFS);
803 case BTRFS_SHARED_DATA_REF_KEY: {
804 struct btrfs_shared_data_ref *sdref;
807 sdref = btrfs_item_ptr(leaf, slot,
808 struct btrfs_shared_data_ref);
809 count = btrfs_shared_data_ref_count(leaf, sdref);
810 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
811 bytenr, count, GFP_NOFS);
814 case BTRFS_TREE_BLOCK_REF_KEY:
815 ret = __add_prelim_ref(prefs, key.offset, NULL,
817 bytenr, 1, GFP_NOFS);
819 case BTRFS_EXTENT_DATA_REF_KEY: {
820 struct btrfs_extent_data_ref *dref;
824 dref = btrfs_item_ptr(leaf, slot,
825 struct btrfs_extent_data_ref);
826 count = btrfs_extent_data_ref_count(leaf, dref);
827 key.objectid = btrfs_extent_data_ref_objectid(leaf,
829 key.type = BTRFS_EXTENT_DATA_KEY;
830 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
831 root = btrfs_extent_data_ref_root(leaf, dref);
832 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
833 bytenr, count, GFP_NOFS);
848 * this adds all existing backrefs (inline backrefs, backrefs and delayed
849 * refs) for the given bytenr to the refs list, merges duplicates and resolves
850 * indirect refs to their parent bytenr.
851 * When roots are found, they're added to the roots list
853 * FIXME some caching might speed things up
855 static int find_parent_nodes(struct btrfs_trans_handle *trans,
856 struct btrfs_fs_info *fs_info, u64 bytenr,
857 u64 time_seq, struct ulist *refs,
858 struct ulist *roots, const u64 *extent_item_pos)
860 struct btrfs_key key;
861 struct btrfs_path *path;
862 struct btrfs_delayed_ref_root *delayed_refs = NULL;
863 struct btrfs_delayed_ref_head *head;
866 struct list_head prefs_delayed;
867 struct list_head prefs;
868 struct __prelim_ref *ref;
869 struct extent_inode_elem *eie = NULL;
872 INIT_LIST_HEAD(&prefs);
873 INIT_LIST_HEAD(&prefs_delayed);
875 key.objectid = bytenr;
876 key.offset = (u64)-1;
877 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
878 key.type = BTRFS_METADATA_ITEM_KEY;
880 key.type = BTRFS_EXTENT_ITEM_KEY;
882 path = btrfs_alloc_path();
886 path->search_commit_root = 1;
887 path->skip_locking = 1;
891 * grab both a lock on the path and a lock on the delayed ref head.
892 * We need both to get a consistent picture of how the refs look
893 * at a specified point in time
898 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
905 * look if there are updates for this ref queued and lock the
908 delayed_refs = &trans->transaction->delayed_refs;
909 spin_lock(&delayed_refs->lock);
910 head = btrfs_find_delayed_ref_head(trans, bytenr);
912 if (!mutex_trylock(&head->mutex)) {
913 atomic_inc(&head->node.refs);
914 spin_unlock(&delayed_refs->lock);
916 btrfs_release_path(path);
919 * Mutex was contended, block until it's
920 * released and try again
922 mutex_lock(&head->mutex);
923 mutex_unlock(&head->mutex);
924 btrfs_put_delayed_ref(&head->node);
927 spin_unlock(&delayed_refs->lock);
928 ret = __add_delayed_refs(head, time_seq,
929 &prefs_delayed, &total_refs);
930 mutex_unlock(&head->mutex);
934 spin_unlock(&delayed_refs->lock);
938 if (path->slots[0]) {
939 struct extent_buffer *leaf;
943 leaf = path->nodes[0];
944 slot = path->slots[0];
945 btrfs_item_key_to_cpu(leaf, &key, slot);
946 if (key.objectid == bytenr &&
947 (key.type == BTRFS_EXTENT_ITEM_KEY ||
948 key.type == BTRFS_METADATA_ITEM_KEY)) {
949 ret = __add_inline_refs(fs_info, path, bytenr,
954 ret = __add_keyed_refs(fs_info, path, bytenr,
960 btrfs_release_path(path);
962 list_splice_init(&prefs_delayed, &prefs);
964 ret = __add_missing_keys(fs_info, &prefs);
968 __merge_refs(&prefs, 1);
970 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
971 extent_item_pos, total_refs);
975 __merge_refs(&prefs, 2);
977 while (!list_empty(&prefs)) {
978 ref = list_first_entry(&prefs, struct __prelim_ref, list);
979 WARN_ON(ref->count < 0);
980 if (roots && ref->count && ref->root_id && ref->parent == 0) {
981 /* no parent == root of tree */
982 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
986 if (ref->count && ref->parent) {
987 if (extent_item_pos && !ref->inode_list) {
989 struct extent_buffer *eb;
990 bsz = btrfs_level_size(fs_info->extent_root,
992 eb = read_tree_block(fs_info->extent_root,
993 ref->parent, bsz, 0);
994 if (!eb || !extent_buffer_uptodate(eb)) {
995 free_extent_buffer(eb);
999 ret = find_extent_in_eb(eb, bytenr,
1000 *extent_item_pos, &eie);
1001 free_extent_buffer(eb);
1004 ref->inode_list = eie;
1006 ret = ulist_add_merge(refs, ref->parent,
1007 (uintptr_t)ref->inode_list,
1008 (u64 *)&eie, GFP_NOFS);
1011 if (!ret && extent_item_pos) {
1013 * we've recorded that parent, so we must extend
1014 * its inode list here
1019 eie->next = ref->inode_list;
1023 list_del(&ref->list);
1024 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1028 btrfs_free_path(path);
1029 while (!list_empty(&prefs)) {
1030 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1031 list_del(&ref->list);
1032 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1034 while (!list_empty(&prefs_delayed)) {
1035 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
1037 list_del(&ref->list);
1038 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1041 free_inode_elem_list(eie);
1045 static void free_leaf_list(struct ulist *blocks)
1047 struct ulist_node *node = NULL;
1048 struct extent_inode_elem *eie;
1049 struct ulist_iterator uiter;
1051 ULIST_ITER_INIT(&uiter);
1052 while ((node = ulist_next(blocks, &uiter))) {
1055 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1056 free_inode_elem_list(eie);
1064 * Finds all leafs with a reference to the specified combination of bytenr and
1065 * offset. key_list_head will point to a list of corresponding keys (caller must
1066 * free each list element). The leafs will be stored in the leafs ulist, which
1067 * must be freed with ulist_free.
1069 * returns 0 on success, <0 on error
1071 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1072 struct btrfs_fs_info *fs_info, u64 bytenr,
1073 u64 time_seq, struct ulist **leafs,
1074 const u64 *extent_item_pos)
1078 *leafs = ulist_alloc(GFP_NOFS);
1082 ret = find_parent_nodes(trans, fs_info, bytenr,
1083 time_seq, *leafs, NULL, extent_item_pos);
1084 if (ret < 0 && ret != -ENOENT) {
1085 free_leaf_list(*leafs);
1093 * walk all backrefs for a given extent to find all roots that reference this
1094 * extent. Walking a backref means finding all extents that reference this
1095 * extent and in turn walk the backrefs of those, too. Naturally this is a
1096 * recursive process, but here it is implemented in an iterative fashion: We
1097 * find all referencing extents for the extent in question and put them on a
1098 * list. In turn, we find all referencing extents for those, further appending
1099 * to the list. The way we iterate the list allows adding more elements after
1100 * the current while iterating. The process stops when we reach the end of the
1101 * list. Found roots are added to the roots list.
1103 * returns 0 on success, < 0 on error.
1105 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1106 struct btrfs_fs_info *fs_info, u64 bytenr,
1107 u64 time_seq, struct ulist **roots)
1110 struct ulist_node *node = NULL;
1111 struct ulist_iterator uiter;
1114 tmp = ulist_alloc(GFP_NOFS);
1117 *roots = ulist_alloc(GFP_NOFS);
1123 ULIST_ITER_INIT(&uiter);
1125 ret = find_parent_nodes(trans, fs_info, bytenr,
1126 time_seq, tmp, *roots, NULL);
1127 if (ret < 0 && ret != -ENOENT) {
1132 node = ulist_next(tmp, &uiter);
1143 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1144 struct btrfs_fs_info *fs_info, u64 bytenr,
1145 u64 time_seq, struct ulist **roots)
1150 down_read(&fs_info->commit_root_sem);
1151 ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
1153 up_read(&fs_info->commit_root_sem);
1158 * this makes the path point to (inum INODE_ITEM ioff)
1160 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1161 struct btrfs_path *path)
1163 struct btrfs_key key;
1164 return btrfs_find_item(fs_root, path, inum, ioff,
1165 BTRFS_INODE_ITEM_KEY, &key);
1168 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1169 struct btrfs_path *path,
1170 struct btrfs_key *found_key)
1172 return btrfs_find_item(fs_root, path, inum, ioff,
1173 BTRFS_INODE_REF_KEY, found_key);
1176 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1177 u64 start_off, struct btrfs_path *path,
1178 struct btrfs_inode_extref **ret_extref,
1182 struct btrfs_key key;
1183 struct btrfs_key found_key;
1184 struct btrfs_inode_extref *extref;
1185 struct extent_buffer *leaf;
1188 key.objectid = inode_objectid;
1189 btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1190 key.offset = start_off;
1192 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1197 leaf = path->nodes[0];
1198 slot = path->slots[0];
1199 if (slot >= btrfs_header_nritems(leaf)) {
1201 * If the item at offset is not found,
1202 * btrfs_search_slot will point us to the slot
1203 * where it should be inserted. In our case
1204 * that will be the slot directly before the
1205 * next INODE_REF_KEY_V2 item. In the case
1206 * that we're pointing to the last slot in a
1207 * leaf, we must move one leaf over.
1209 ret = btrfs_next_leaf(root, path);
1218 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1221 * Check that we're still looking at an extended ref key for
1222 * this particular objectid. If we have different
1223 * objectid or type then there are no more to be found
1224 * in the tree and we can exit.
1227 if (found_key.objectid != inode_objectid)
1229 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1233 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1234 extref = (struct btrfs_inode_extref *)ptr;
1235 *ret_extref = extref;
1237 *found_off = found_key.offset;
1245 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1246 * Elements of the path are separated by '/' and the path is guaranteed to be
1247 * 0-terminated. the path is only given within the current file system.
1248 * Therefore, it never starts with a '/'. the caller is responsible to provide
1249 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1250 * the start point of the resulting string is returned. this pointer is within
1252 * in case the path buffer would overflow, the pointer is decremented further
1253 * as if output was written to the buffer, though no more output is actually
1254 * generated. that way, the caller can determine how much space would be
1255 * required for the path to fit into the buffer. in that case, the returned
1256 * value will be smaller than dest. callers must check this!
1258 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1259 u32 name_len, unsigned long name_off,
1260 struct extent_buffer *eb_in, u64 parent,
1261 char *dest, u32 size)
1266 s64 bytes_left = ((s64)size) - 1;
1267 struct extent_buffer *eb = eb_in;
1268 struct btrfs_key found_key;
1269 int leave_spinning = path->leave_spinning;
1270 struct btrfs_inode_ref *iref;
1272 if (bytes_left >= 0)
1273 dest[bytes_left] = '\0';
1275 path->leave_spinning = 1;
1277 bytes_left -= name_len;
1278 if (bytes_left >= 0)
1279 read_extent_buffer(eb, dest + bytes_left,
1280 name_off, name_len);
1282 btrfs_tree_read_unlock_blocking(eb);
1283 free_extent_buffer(eb);
1285 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1291 next_inum = found_key.offset;
1293 /* regular exit ahead */
1294 if (parent == next_inum)
1297 slot = path->slots[0];
1298 eb = path->nodes[0];
1299 /* make sure we can use eb after releasing the path */
1301 atomic_inc(&eb->refs);
1302 btrfs_tree_read_lock(eb);
1303 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1305 btrfs_release_path(path);
1306 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1308 name_len = btrfs_inode_ref_name_len(eb, iref);
1309 name_off = (unsigned long)(iref + 1);
1313 if (bytes_left >= 0)
1314 dest[bytes_left] = '/';
1317 btrfs_release_path(path);
1318 path->leave_spinning = leave_spinning;
1321 return ERR_PTR(ret);
1323 return dest + bytes_left;
1327 * this makes the path point to (logical EXTENT_ITEM *)
1328 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1329 * tree blocks and <0 on error.
1331 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1332 struct btrfs_path *path, struct btrfs_key *found_key,
1339 struct extent_buffer *eb;
1340 struct btrfs_extent_item *ei;
1341 struct btrfs_key key;
1343 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1344 key.type = BTRFS_METADATA_ITEM_KEY;
1346 key.type = BTRFS_EXTENT_ITEM_KEY;
1347 key.objectid = logical;
1348 key.offset = (u64)-1;
1350 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1354 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1360 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1361 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1362 size = fs_info->extent_root->leafsize;
1363 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1364 size = found_key->offset;
1366 if (found_key->objectid > logical ||
1367 found_key->objectid + size <= logical) {
1368 pr_debug("logical %llu is not within any extent\n", logical);
1372 eb = path->nodes[0];
1373 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1374 BUG_ON(item_size < sizeof(*ei));
1376 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1377 flags = btrfs_extent_flags(eb, ei);
1379 pr_debug("logical %llu is at position %llu within the extent (%llu "
1380 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1381 logical, logical - found_key->objectid, found_key->objectid,
1382 found_key->offset, flags, item_size);
1384 WARN_ON(!flags_ret);
1386 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1387 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1388 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1389 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1399 * helper function to iterate extent inline refs. ptr must point to a 0 value
1400 * for the first call and may be modified. it is used to track state.
1401 * if more refs exist, 0 is returned and the next call to
1402 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1403 * next ref. after the last ref was processed, 1 is returned.
1404 * returns <0 on error
1406 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1407 struct btrfs_extent_item *ei, u32 item_size,
1408 struct btrfs_extent_inline_ref **out_eiref,
1413 struct btrfs_tree_block_info *info;
1417 flags = btrfs_extent_flags(eb, ei);
1418 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1419 info = (struct btrfs_tree_block_info *)(ei + 1);
1421 (struct btrfs_extent_inline_ref *)(info + 1);
1423 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1425 *ptr = (unsigned long)*out_eiref;
1426 if ((void *)*ptr >= (void *)ei + item_size)
1430 end = (unsigned long)ei + item_size;
1431 *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1432 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1434 *ptr += btrfs_extent_inline_ref_size(*out_type);
1435 WARN_ON(*ptr > end);
1437 return 1; /* last */
1443 * reads the tree block backref for an extent. tree level and root are returned
1444 * through out_level and out_root. ptr must point to a 0 value for the first
1445 * call and may be modified (see __get_extent_inline_ref comment).
1446 * returns 0 if data was provided, 1 if there was no more data to provide or
1449 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1450 struct btrfs_extent_item *ei, u32 item_size,
1451 u64 *out_root, u8 *out_level)
1455 struct btrfs_tree_block_info *info;
1456 struct btrfs_extent_inline_ref *eiref;
1458 if (*ptr == (unsigned long)-1)
1462 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1467 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1468 type == BTRFS_SHARED_BLOCK_REF_KEY)
1475 /* we can treat both ref types equally here */
1476 info = (struct btrfs_tree_block_info *)(ei + 1);
1477 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1478 *out_level = btrfs_tree_block_level(eb, info);
1481 *ptr = (unsigned long)-1;
1486 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1487 u64 root, u64 extent_item_objectid,
1488 iterate_extent_inodes_t *iterate, void *ctx)
1490 struct extent_inode_elem *eie;
1493 for (eie = inode_list; eie; eie = eie->next) {
1494 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1495 "root %llu\n", extent_item_objectid,
1496 eie->inum, eie->offset, root);
1497 ret = iterate(eie->inum, eie->offset, root, ctx);
1499 pr_debug("stopping iteration for %llu due to ret=%d\n",
1500 extent_item_objectid, ret);
1509 * calls iterate() for every inode that references the extent identified by
1510 * the given parameters.
1511 * when the iterator function returns a non-zero value, iteration stops.
1513 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1514 u64 extent_item_objectid, u64 extent_item_pos,
1515 int search_commit_root,
1516 iterate_extent_inodes_t *iterate, void *ctx)
1519 struct btrfs_trans_handle *trans = NULL;
1520 struct ulist *refs = NULL;
1521 struct ulist *roots = NULL;
1522 struct ulist_node *ref_node = NULL;
1523 struct ulist_node *root_node = NULL;
1524 struct seq_list tree_mod_seq_elem = {};
1525 struct ulist_iterator ref_uiter;
1526 struct ulist_iterator root_uiter;
1528 pr_debug("resolving all inodes for extent %llu\n",
1529 extent_item_objectid);
1531 if (!search_commit_root) {
1532 trans = btrfs_join_transaction(fs_info->extent_root);
1534 return PTR_ERR(trans);
1535 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1537 down_read(&fs_info->commit_root_sem);
1540 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1541 tree_mod_seq_elem.seq, &refs,
1546 ULIST_ITER_INIT(&ref_uiter);
1547 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1548 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
1549 tree_mod_seq_elem.seq, &roots);
1552 ULIST_ITER_INIT(&root_uiter);
1553 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1554 pr_debug("root %llu references leaf %llu, data list "
1555 "%#llx\n", root_node->val, ref_node->val,
1557 ret = iterate_leaf_refs((struct extent_inode_elem *)
1558 (uintptr_t)ref_node->aux,
1560 extent_item_objectid,
1566 free_leaf_list(refs);
1568 if (!search_commit_root) {
1569 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1570 btrfs_end_transaction(trans, fs_info->extent_root);
1572 up_read(&fs_info->commit_root_sem);
1578 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1579 struct btrfs_path *path,
1580 iterate_extent_inodes_t *iterate, void *ctx)
1583 u64 extent_item_pos;
1585 struct btrfs_key found_key;
1586 int search_commit_root = path->search_commit_root;
1588 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1589 btrfs_release_path(path);
1592 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1595 extent_item_pos = logical - found_key.objectid;
1596 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1597 extent_item_pos, search_commit_root,
1603 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1604 struct extent_buffer *eb, void *ctx);
1606 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1607 struct btrfs_path *path,
1608 iterate_irefs_t *iterate, void *ctx)
1617 struct extent_buffer *eb;
1618 struct btrfs_item *item;
1619 struct btrfs_inode_ref *iref;
1620 struct btrfs_key found_key;
1623 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1628 ret = found ? 0 : -ENOENT;
1633 parent = found_key.offset;
1634 slot = path->slots[0];
1635 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1640 extent_buffer_get(eb);
1641 btrfs_tree_read_lock(eb);
1642 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1643 btrfs_release_path(path);
1645 item = btrfs_item_nr(slot);
1646 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1648 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1649 name_len = btrfs_inode_ref_name_len(eb, iref);
1650 /* path must be released before calling iterate()! */
1651 pr_debug("following ref at offset %u for inode %llu in "
1652 "tree %llu\n", cur, found_key.objectid,
1654 ret = iterate(parent, name_len,
1655 (unsigned long)(iref + 1), eb, ctx);
1658 len = sizeof(*iref) + name_len;
1659 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1661 btrfs_tree_read_unlock_blocking(eb);
1662 free_extent_buffer(eb);
1665 btrfs_release_path(path);
1670 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1671 struct btrfs_path *path,
1672 iterate_irefs_t *iterate, void *ctx)
1679 struct extent_buffer *eb;
1680 struct btrfs_inode_extref *extref;
1681 struct extent_buffer *leaf;
1687 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1692 ret = found ? 0 : -ENOENT;
1697 slot = path->slots[0];
1698 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1703 extent_buffer_get(eb);
1705 btrfs_tree_read_lock(eb);
1706 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1707 btrfs_release_path(path);
1709 leaf = path->nodes[0];
1710 item_size = btrfs_item_size_nr(leaf, slot);
1711 ptr = btrfs_item_ptr_offset(leaf, slot);
1714 while (cur_offset < item_size) {
1717 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1718 parent = btrfs_inode_extref_parent(eb, extref);
1719 name_len = btrfs_inode_extref_name_len(eb, extref);
1720 ret = iterate(parent, name_len,
1721 (unsigned long)&extref->name, eb, ctx);
1725 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1726 cur_offset += sizeof(*extref);
1728 btrfs_tree_read_unlock_blocking(eb);
1729 free_extent_buffer(eb);
1734 btrfs_release_path(path);
1739 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1740 struct btrfs_path *path, iterate_irefs_t *iterate,
1746 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1749 else if (ret != -ENOENT)
1752 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1753 if (ret == -ENOENT && found_refs)
1760 * returns 0 if the path could be dumped (probably truncated)
1761 * returns <0 in case of an error
1763 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1764 struct extent_buffer *eb, void *ctx)
1766 struct inode_fs_paths *ipath = ctx;
1769 int i = ipath->fspath->elem_cnt;
1770 const int s_ptr = sizeof(char *);
1773 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1774 ipath->fspath->bytes_left - s_ptr : 0;
1776 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1777 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1778 name_off, eb, inum, fspath_min, bytes_left);
1780 return PTR_ERR(fspath);
1782 if (fspath > fspath_min) {
1783 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1784 ++ipath->fspath->elem_cnt;
1785 ipath->fspath->bytes_left = fspath - fspath_min;
1787 ++ipath->fspath->elem_missed;
1788 ipath->fspath->bytes_missing += fspath_min - fspath;
1789 ipath->fspath->bytes_left = 0;
1796 * this dumps all file system paths to the inode into the ipath struct, provided
1797 * is has been created large enough. each path is zero-terminated and accessed
1798 * from ipath->fspath->val[i].
1799 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1800 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1801 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1802 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1803 * have been needed to return all paths.
1805 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1807 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1808 inode_to_path, ipath);
1811 struct btrfs_data_container *init_data_container(u32 total_bytes)
1813 struct btrfs_data_container *data;
1816 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1817 data = vmalloc(alloc_bytes);
1819 return ERR_PTR(-ENOMEM);
1821 if (total_bytes >= sizeof(*data)) {
1822 data->bytes_left = total_bytes - sizeof(*data);
1823 data->bytes_missing = 0;
1825 data->bytes_missing = sizeof(*data) - total_bytes;
1826 data->bytes_left = 0;
1830 data->elem_missed = 0;
1836 * allocates space to return multiple file system paths for an inode.
1837 * total_bytes to allocate are passed, note that space usable for actual path
1838 * information will be total_bytes - sizeof(struct inode_fs_paths).
1839 * the returned pointer must be freed with free_ipath() in the end.
1841 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1842 struct btrfs_path *path)
1844 struct inode_fs_paths *ifp;
1845 struct btrfs_data_container *fspath;
1847 fspath = init_data_container(total_bytes);
1849 return (void *)fspath;
1851 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1854 return ERR_PTR(-ENOMEM);
1857 ifp->btrfs_path = path;
1858 ifp->fspath = fspath;
1859 ifp->fs_root = fs_root;
1864 void free_ipath(struct inode_fs_paths *ipath)
1868 vfree(ipath->fspath);