Linux 3.8-rc7
[cris-mirror.git] / fs / btrfs / backref.c
blob04edf69be87561318375716abeb1d854370c63c3
1 /*
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>
20 #include "ctree.h"
21 #include "disk-io.h"
22 #include "backref.h"
23 #include "ulist.h"
24 #include "transaction.h"
25 #include "delayed-ref.h"
26 #include "locking.h"
28 struct extent_inode_elem {
29 u64 inum;
30 u64 offset;
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,
36 u64 extent_item_pos,
37 struct extent_inode_elem **eie)
39 u64 data_offset;
40 u64 data_len;
41 struct extent_inode_elem *e;
43 data_offset = btrfs_file_extent_offset(eb, fi);
44 data_len = btrfs_file_extent_num_bytes(eb, fi);
46 if (extent_item_pos < data_offset ||
47 extent_item_pos >= data_offset + data_len)
48 return 1;
50 e = kmalloc(sizeof(*e), GFP_NOFS);
51 if (!e)
52 return -ENOMEM;
54 e->next = *eie;
55 e->inum = key->objectid;
56 e->offset = key->offset + (extent_item_pos - data_offset);
57 *eie = e;
59 return 0;
62 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
63 u64 extent_item_pos,
64 struct extent_inode_elem **eie)
66 u64 disk_byte;
67 struct btrfs_key key;
68 struct btrfs_file_extent_item *fi;
69 int slot;
70 int nritems;
71 int extent_type;
72 int ret;
75 * from the shared data ref, we only have the leaf but we need
76 * the key. thus, we must look into all items and see that we
77 * find one (some) with a reference to our extent item.
79 nritems = btrfs_header_nritems(eb);
80 for (slot = 0; slot < nritems; ++slot) {
81 btrfs_item_key_to_cpu(eb, &key, slot);
82 if (key.type != BTRFS_EXTENT_DATA_KEY)
83 continue;
84 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
85 extent_type = btrfs_file_extent_type(eb, fi);
86 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
87 continue;
88 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
89 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
90 if (disk_byte != wanted_disk_byte)
91 continue;
93 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
94 if (ret < 0)
95 return ret;
98 return 0;
102 * this structure records all encountered refs on the way up to the root
104 struct __prelim_ref {
105 struct list_head list;
106 u64 root_id;
107 struct btrfs_key key_for_search;
108 int level;
109 int count;
110 struct extent_inode_elem *inode_list;
111 u64 parent;
112 u64 wanted_disk_byte;
116 * the rules for all callers of this function are:
117 * - obtaining the parent is the goal
118 * - if you add a key, you must know that it is a correct key
119 * - if you cannot add the parent or a correct key, then we will look into the
120 * block later to set a correct key
122 * delayed refs
123 * ============
124 * backref type | shared | indirect | shared | indirect
125 * information | tree | tree | data | data
126 * --------------------+--------+----------+--------+----------
127 * parent logical | y | - | - | -
128 * key to resolve | - | y | y | y
129 * tree block logical | - | - | - | -
130 * root for resolving | y | y | y | y
132 * - column 1: we've the parent -> done
133 * - column 2, 3, 4: we use the key to find the parent
135 * on disk refs (inline or keyed)
136 * ==============================
137 * backref type | shared | indirect | shared | indirect
138 * information | tree | tree | data | data
139 * --------------------+--------+----------+--------+----------
140 * parent logical | y | - | y | -
141 * key to resolve | - | - | - | y
142 * tree block logical | y | y | y | y
143 * root for resolving | - | y | y | y
145 * - column 1, 3: we've the parent -> done
146 * - column 2: we take the first key from the block to find the parent
147 * (see __add_missing_keys)
148 * - column 4: we use the key to find the parent
150 * additional information that's available but not required to find the parent
151 * block might help in merging entries to gain some speed.
154 static int __add_prelim_ref(struct list_head *head, u64 root_id,
155 struct btrfs_key *key, int level,
156 u64 parent, u64 wanted_disk_byte, int count)
158 struct __prelim_ref *ref;
160 /* in case we're adding delayed refs, we're holding the refs spinlock */
161 ref = kmalloc(sizeof(*ref), GFP_ATOMIC);
162 if (!ref)
163 return -ENOMEM;
165 ref->root_id = root_id;
166 if (key)
167 ref->key_for_search = *key;
168 else
169 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
171 ref->inode_list = NULL;
172 ref->level = level;
173 ref->count = count;
174 ref->parent = parent;
175 ref->wanted_disk_byte = wanted_disk_byte;
176 list_add_tail(&ref->list, head);
178 return 0;
181 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
182 struct ulist *parents, int level,
183 struct btrfs_key *key_for_search, u64 time_seq,
184 u64 wanted_disk_byte,
185 const u64 *extent_item_pos)
187 int ret = 0;
188 int slot;
189 struct extent_buffer *eb;
190 struct btrfs_key key;
191 struct btrfs_file_extent_item *fi;
192 struct extent_inode_elem *eie = NULL;
193 u64 disk_byte;
195 if (level != 0) {
196 eb = path->nodes[level];
197 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
198 if (ret < 0)
199 return ret;
200 return 0;
204 * We normally enter this function with the path already pointing to
205 * the first item to check. But sometimes, we may enter it with
206 * slot==nritems. In that case, go to the next leaf before we continue.
208 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
209 ret = btrfs_next_old_leaf(root, path, time_seq);
211 while (!ret) {
212 eb = path->nodes[0];
213 slot = path->slots[0];
215 btrfs_item_key_to_cpu(eb, &key, slot);
217 if (key.objectid != key_for_search->objectid ||
218 key.type != BTRFS_EXTENT_DATA_KEY)
219 break;
221 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
222 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
224 if (disk_byte == wanted_disk_byte) {
225 eie = NULL;
226 if (extent_item_pos) {
227 ret = check_extent_in_eb(&key, eb, fi,
228 *extent_item_pos,
229 &eie);
230 if (ret < 0)
231 break;
233 if (!ret) {
234 ret = ulist_add(parents, eb->start,
235 (uintptr_t)eie, GFP_NOFS);
236 if (ret < 0)
237 break;
238 if (!extent_item_pos) {
239 ret = btrfs_next_old_leaf(root, path,
240 time_seq);
241 continue;
245 ret = btrfs_next_old_item(root, path, time_seq);
248 if (ret > 0)
249 ret = 0;
250 return ret;
254 * resolve an indirect backref in the form (root_id, key, level)
255 * to a logical address
257 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
258 int search_commit_root,
259 u64 time_seq,
260 struct __prelim_ref *ref,
261 struct ulist *parents,
262 const u64 *extent_item_pos)
264 struct btrfs_path *path;
265 struct btrfs_root *root;
266 struct btrfs_key root_key;
267 struct extent_buffer *eb;
268 int ret = 0;
269 int root_level;
270 int level = ref->level;
272 path = btrfs_alloc_path();
273 if (!path)
274 return -ENOMEM;
275 path->search_commit_root = !!search_commit_root;
277 root_key.objectid = ref->root_id;
278 root_key.type = BTRFS_ROOT_ITEM_KEY;
279 root_key.offset = (u64)-1;
280 root = btrfs_read_fs_root_no_name(fs_info, &root_key);
281 if (IS_ERR(root)) {
282 ret = PTR_ERR(root);
283 goto out;
286 root_level = btrfs_old_root_level(root, time_seq);
288 if (root_level + 1 == level)
289 goto out;
291 path->lowest_level = level;
292 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
293 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
294 "%d for key (%llu %u %llu)\n",
295 (unsigned long long)ref->root_id, level, ref->count, ret,
296 (unsigned long long)ref->key_for_search.objectid,
297 ref->key_for_search.type,
298 (unsigned long long)ref->key_for_search.offset);
299 if (ret < 0)
300 goto out;
302 eb = path->nodes[level];
303 while (!eb) {
304 if (!level) {
305 WARN_ON(1);
306 ret = 1;
307 goto out;
309 level--;
310 eb = path->nodes[level];
313 ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
314 time_seq, ref->wanted_disk_byte,
315 extent_item_pos);
316 out:
317 btrfs_free_path(path);
318 return ret;
322 * resolve all indirect backrefs from the list
324 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
325 int search_commit_root, u64 time_seq,
326 struct list_head *head,
327 const u64 *extent_item_pos)
329 int err;
330 int ret = 0;
331 struct __prelim_ref *ref;
332 struct __prelim_ref *ref_safe;
333 struct __prelim_ref *new_ref;
334 struct ulist *parents;
335 struct ulist_node *node;
336 struct ulist_iterator uiter;
338 parents = ulist_alloc(GFP_NOFS);
339 if (!parents)
340 return -ENOMEM;
343 * _safe allows us to insert directly after the current item without
344 * iterating over the newly inserted items.
345 * we're also allowed to re-assign ref during iteration.
347 list_for_each_entry_safe(ref, ref_safe, head, list) {
348 if (ref->parent) /* already direct */
349 continue;
350 if (ref->count == 0)
351 continue;
352 err = __resolve_indirect_ref(fs_info, search_commit_root,
353 time_seq, ref, parents,
354 extent_item_pos);
355 if (err) {
356 if (ret == 0)
357 ret = err;
358 continue;
361 /* we put the first parent into the ref at hand */
362 ULIST_ITER_INIT(&uiter);
363 node = ulist_next(parents, &uiter);
364 ref->parent = node ? node->val : 0;
365 ref->inode_list = node ?
366 (struct extent_inode_elem *)(uintptr_t)node->aux : 0;
368 /* additional parents require new refs being added here */
369 while ((node = ulist_next(parents, &uiter))) {
370 new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
371 if (!new_ref) {
372 ret = -ENOMEM;
373 break;
375 memcpy(new_ref, ref, sizeof(*ref));
376 new_ref->parent = node->val;
377 new_ref->inode_list = (struct extent_inode_elem *)
378 (uintptr_t)node->aux;
379 list_add(&new_ref->list, &ref->list);
381 ulist_reinit(parents);
384 ulist_free(parents);
385 return ret;
388 static inline int ref_for_same_block(struct __prelim_ref *ref1,
389 struct __prelim_ref *ref2)
391 if (ref1->level != ref2->level)
392 return 0;
393 if (ref1->root_id != ref2->root_id)
394 return 0;
395 if (ref1->key_for_search.type != ref2->key_for_search.type)
396 return 0;
397 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
398 return 0;
399 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
400 return 0;
401 if (ref1->parent != ref2->parent)
402 return 0;
404 return 1;
408 * read tree blocks and add keys where required.
410 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
411 struct list_head *head)
413 struct list_head *pos;
414 struct extent_buffer *eb;
416 list_for_each(pos, head) {
417 struct __prelim_ref *ref;
418 ref = list_entry(pos, struct __prelim_ref, list);
420 if (ref->parent)
421 continue;
422 if (ref->key_for_search.type)
423 continue;
424 BUG_ON(!ref->wanted_disk_byte);
425 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
426 fs_info->tree_root->leafsize, 0);
427 BUG_ON(!eb);
428 btrfs_tree_read_lock(eb);
429 if (btrfs_header_level(eb) == 0)
430 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
431 else
432 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
433 btrfs_tree_read_unlock(eb);
434 free_extent_buffer(eb);
436 return 0;
440 * merge two lists of backrefs and adjust counts accordingly
442 * mode = 1: merge identical keys, if key is set
443 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
444 * additionally, we could even add a key range for the blocks we
445 * looked into to merge even more (-> replace unresolved refs by those
446 * having a parent).
447 * mode = 2: merge identical parents
449 static int __merge_refs(struct list_head *head, int mode)
451 struct list_head *pos1;
453 list_for_each(pos1, head) {
454 struct list_head *n2;
455 struct list_head *pos2;
456 struct __prelim_ref *ref1;
458 ref1 = list_entry(pos1, struct __prelim_ref, list);
460 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
461 pos2 = n2, n2 = pos2->next) {
462 struct __prelim_ref *ref2;
463 struct __prelim_ref *xchg;
464 struct extent_inode_elem *eie;
466 ref2 = list_entry(pos2, struct __prelim_ref, list);
468 if (mode == 1) {
469 if (!ref_for_same_block(ref1, ref2))
470 continue;
471 if (!ref1->parent && ref2->parent) {
472 xchg = ref1;
473 ref1 = ref2;
474 ref2 = xchg;
476 } else {
477 if (ref1->parent != ref2->parent)
478 continue;
481 eie = ref1->inode_list;
482 while (eie && eie->next)
483 eie = eie->next;
484 if (eie)
485 eie->next = ref2->inode_list;
486 else
487 ref1->inode_list = ref2->inode_list;
488 ref1->count += ref2->count;
490 list_del(&ref2->list);
491 kfree(ref2);
495 return 0;
499 * add all currently queued delayed refs from this head whose seq nr is
500 * smaller or equal that seq to the list
502 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
503 struct list_head *prefs)
505 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
506 struct rb_node *n = &head->node.rb_node;
507 struct btrfs_key key;
508 struct btrfs_key op_key = {0};
509 int sgn;
510 int ret = 0;
512 if (extent_op && extent_op->update_key)
513 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
515 while ((n = rb_prev(n))) {
516 struct btrfs_delayed_ref_node *node;
517 node = rb_entry(n, struct btrfs_delayed_ref_node,
518 rb_node);
519 if (node->bytenr != head->node.bytenr)
520 break;
521 WARN_ON(node->is_head);
523 if (node->seq > seq)
524 continue;
526 switch (node->action) {
527 case BTRFS_ADD_DELAYED_EXTENT:
528 case BTRFS_UPDATE_DELAYED_HEAD:
529 WARN_ON(1);
530 continue;
531 case BTRFS_ADD_DELAYED_REF:
532 sgn = 1;
533 break;
534 case BTRFS_DROP_DELAYED_REF:
535 sgn = -1;
536 break;
537 default:
538 BUG_ON(1);
540 switch (node->type) {
541 case BTRFS_TREE_BLOCK_REF_KEY: {
542 struct btrfs_delayed_tree_ref *ref;
544 ref = btrfs_delayed_node_to_tree_ref(node);
545 ret = __add_prelim_ref(prefs, ref->root, &op_key,
546 ref->level + 1, 0, node->bytenr,
547 node->ref_mod * sgn);
548 break;
550 case BTRFS_SHARED_BLOCK_REF_KEY: {
551 struct btrfs_delayed_tree_ref *ref;
553 ref = btrfs_delayed_node_to_tree_ref(node);
554 ret = __add_prelim_ref(prefs, ref->root, NULL,
555 ref->level + 1, ref->parent,
556 node->bytenr,
557 node->ref_mod * sgn);
558 break;
560 case BTRFS_EXTENT_DATA_REF_KEY: {
561 struct btrfs_delayed_data_ref *ref;
562 ref = btrfs_delayed_node_to_data_ref(node);
564 key.objectid = ref->objectid;
565 key.type = BTRFS_EXTENT_DATA_KEY;
566 key.offset = ref->offset;
567 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
568 node->bytenr,
569 node->ref_mod * sgn);
570 break;
572 case BTRFS_SHARED_DATA_REF_KEY: {
573 struct btrfs_delayed_data_ref *ref;
575 ref = btrfs_delayed_node_to_data_ref(node);
577 key.objectid = ref->objectid;
578 key.type = BTRFS_EXTENT_DATA_KEY;
579 key.offset = ref->offset;
580 ret = __add_prelim_ref(prefs, ref->root, &key, 0,
581 ref->parent, node->bytenr,
582 node->ref_mod * sgn);
583 break;
585 default:
586 WARN_ON(1);
588 BUG_ON(ret);
591 return 0;
595 * add all inline backrefs for bytenr to the list
597 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
598 struct btrfs_path *path, u64 bytenr,
599 int *info_level, struct list_head *prefs)
601 int ret = 0;
602 int slot;
603 struct extent_buffer *leaf;
604 struct btrfs_key key;
605 unsigned long ptr;
606 unsigned long end;
607 struct btrfs_extent_item *ei;
608 u64 flags;
609 u64 item_size;
612 * enumerate all inline refs
614 leaf = path->nodes[0];
615 slot = path->slots[0];
617 item_size = btrfs_item_size_nr(leaf, slot);
618 BUG_ON(item_size < sizeof(*ei));
620 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
621 flags = btrfs_extent_flags(leaf, ei);
623 ptr = (unsigned long)(ei + 1);
624 end = (unsigned long)ei + item_size;
626 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
627 struct btrfs_tree_block_info *info;
629 info = (struct btrfs_tree_block_info *)ptr;
630 *info_level = btrfs_tree_block_level(leaf, info);
631 ptr += sizeof(struct btrfs_tree_block_info);
632 BUG_ON(ptr > end);
633 } else {
634 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
637 while (ptr < end) {
638 struct btrfs_extent_inline_ref *iref;
639 u64 offset;
640 int type;
642 iref = (struct btrfs_extent_inline_ref *)ptr;
643 type = btrfs_extent_inline_ref_type(leaf, iref);
644 offset = btrfs_extent_inline_ref_offset(leaf, iref);
646 switch (type) {
647 case BTRFS_SHARED_BLOCK_REF_KEY:
648 ret = __add_prelim_ref(prefs, 0, NULL,
649 *info_level + 1, offset,
650 bytenr, 1);
651 break;
652 case BTRFS_SHARED_DATA_REF_KEY: {
653 struct btrfs_shared_data_ref *sdref;
654 int count;
656 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
657 count = btrfs_shared_data_ref_count(leaf, sdref);
658 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
659 bytenr, count);
660 break;
662 case BTRFS_TREE_BLOCK_REF_KEY:
663 ret = __add_prelim_ref(prefs, offset, NULL,
664 *info_level + 1, 0,
665 bytenr, 1);
666 break;
667 case BTRFS_EXTENT_DATA_REF_KEY: {
668 struct btrfs_extent_data_ref *dref;
669 int count;
670 u64 root;
672 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
673 count = btrfs_extent_data_ref_count(leaf, dref);
674 key.objectid = btrfs_extent_data_ref_objectid(leaf,
675 dref);
676 key.type = BTRFS_EXTENT_DATA_KEY;
677 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
678 root = btrfs_extent_data_ref_root(leaf, dref);
679 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
680 bytenr, count);
681 break;
683 default:
684 WARN_ON(1);
686 BUG_ON(ret);
687 ptr += btrfs_extent_inline_ref_size(type);
690 return 0;
694 * add all non-inline backrefs for bytenr to the list
696 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
697 struct btrfs_path *path, u64 bytenr,
698 int info_level, struct list_head *prefs)
700 struct btrfs_root *extent_root = fs_info->extent_root;
701 int ret;
702 int slot;
703 struct extent_buffer *leaf;
704 struct btrfs_key key;
706 while (1) {
707 ret = btrfs_next_item(extent_root, path);
708 if (ret < 0)
709 break;
710 if (ret) {
711 ret = 0;
712 break;
715 slot = path->slots[0];
716 leaf = path->nodes[0];
717 btrfs_item_key_to_cpu(leaf, &key, slot);
719 if (key.objectid != bytenr)
720 break;
721 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
722 continue;
723 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
724 break;
726 switch (key.type) {
727 case BTRFS_SHARED_BLOCK_REF_KEY:
728 ret = __add_prelim_ref(prefs, 0, NULL,
729 info_level + 1, key.offset,
730 bytenr, 1);
731 break;
732 case BTRFS_SHARED_DATA_REF_KEY: {
733 struct btrfs_shared_data_ref *sdref;
734 int count;
736 sdref = btrfs_item_ptr(leaf, slot,
737 struct btrfs_shared_data_ref);
738 count = btrfs_shared_data_ref_count(leaf, sdref);
739 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
740 bytenr, count);
741 break;
743 case BTRFS_TREE_BLOCK_REF_KEY:
744 ret = __add_prelim_ref(prefs, key.offset, NULL,
745 info_level + 1, 0,
746 bytenr, 1);
747 break;
748 case BTRFS_EXTENT_DATA_REF_KEY: {
749 struct btrfs_extent_data_ref *dref;
750 int count;
751 u64 root;
753 dref = btrfs_item_ptr(leaf, slot,
754 struct btrfs_extent_data_ref);
755 count = btrfs_extent_data_ref_count(leaf, dref);
756 key.objectid = btrfs_extent_data_ref_objectid(leaf,
757 dref);
758 key.type = BTRFS_EXTENT_DATA_KEY;
759 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
760 root = btrfs_extent_data_ref_root(leaf, dref);
761 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
762 bytenr, count);
763 break;
765 default:
766 WARN_ON(1);
768 BUG_ON(ret);
771 return ret;
775 * this adds all existing backrefs (inline backrefs, backrefs and delayed
776 * refs) for the given bytenr to the refs list, merges duplicates and resolves
777 * indirect refs to their parent bytenr.
778 * When roots are found, they're added to the roots list
780 * FIXME some caching might speed things up
782 static int find_parent_nodes(struct btrfs_trans_handle *trans,
783 struct btrfs_fs_info *fs_info, u64 bytenr,
784 u64 time_seq, struct ulist *refs,
785 struct ulist *roots, const u64 *extent_item_pos)
787 struct btrfs_key key;
788 struct btrfs_path *path;
789 struct btrfs_delayed_ref_root *delayed_refs = NULL;
790 struct btrfs_delayed_ref_head *head;
791 int info_level = 0;
792 int ret;
793 int search_commit_root = (trans == BTRFS_BACKREF_SEARCH_COMMIT_ROOT);
794 struct list_head prefs_delayed;
795 struct list_head prefs;
796 struct __prelim_ref *ref;
798 INIT_LIST_HEAD(&prefs);
799 INIT_LIST_HEAD(&prefs_delayed);
801 key.objectid = bytenr;
802 key.type = BTRFS_EXTENT_ITEM_KEY;
803 key.offset = (u64)-1;
805 path = btrfs_alloc_path();
806 if (!path)
807 return -ENOMEM;
808 path->search_commit_root = !!search_commit_root;
811 * grab both a lock on the path and a lock on the delayed ref head.
812 * We need both to get a consistent picture of how the refs look
813 * at a specified point in time
815 again:
816 head = NULL;
818 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
819 if (ret < 0)
820 goto out;
821 BUG_ON(ret == 0);
823 if (trans != BTRFS_BACKREF_SEARCH_COMMIT_ROOT) {
825 * look if there are updates for this ref queued and lock the
826 * head
828 delayed_refs = &trans->transaction->delayed_refs;
829 spin_lock(&delayed_refs->lock);
830 head = btrfs_find_delayed_ref_head(trans, bytenr);
831 if (head) {
832 if (!mutex_trylock(&head->mutex)) {
833 atomic_inc(&head->node.refs);
834 spin_unlock(&delayed_refs->lock);
836 btrfs_release_path(path);
839 * Mutex was contended, block until it's
840 * released and try again
842 mutex_lock(&head->mutex);
843 mutex_unlock(&head->mutex);
844 btrfs_put_delayed_ref(&head->node);
845 goto again;
847 ret = __add_delayed_refs(head, time_seq,
848 &prefs_delayed);
849 mutex_unlock(&head->mutex);
850 if (ret) {
851 spin_unlock(&delayed_refs->lock);
852 goto out;
855 spin_unlock(&delayed_refs->lock);
858 if (path->slots[0]) {
859 struct extent_buffer *leaf;
860 int slot;
862 path->slots[0]--;
863 leaf = path->nodes[0];
864 slot = path->slots[0];
865 btrfs_item_key_to_cpu(leaf, &key, slot);
866 if (key.objectid == bytenr &&
867 key.type == BTRFS_EXTENT_ITEM_KEY) {
868 ret = __add_inline_refs(fs_info, path, bytenr,
869 &info_level, &prefs);
870 if (ret)
871 goto out;
872 ret = __add_keyed_refs(fs_info, path, bytenr,
873 info_level, &prefs);
874 if (ret)
875 goto out;
878 btrfs_release_path(path);
880 list_splice_init(&prefs_delayed, &prefs);
882 ret = __add_missing_keys(fs_info, &prefs);
883 if (ret)
884 goto out;
886 ret = __merge_refs(&prefs, 1);
887 if (ret)
888 goto out;
890 ret = __resolve_indirect_refs(fs_info, search_commit_root, time_seq,
891 &prefs, extent_item_pos);
892 if (ret)
893 goto out;
895 ret = __merge_refs(&prefs, 2);
896 if (ret)
897 goto out;
899 while (!list_empty(&prefs)) {
900 ref = list_first_entry(&prefs, struct __prelim_ref, list);
901 list_del(&ref->list);
902 WARN_ON(ref->count < 0);
903 if (ref->count && ref->root_id && ref->parent == 0) {
904 /* no parent == root of tree */
905 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
906 BUG_ON(ret < 0);
908 if (ref->count && ref->parent) {
909 struct extent_inode_elem *eie = NULL;
910 if (extent_item_pos && !ref->inode_list) {
911 u32 bsz;
912 struct extent_buffer *eb;
913 bsz = btrfs_level_size(fs_info->extent_root,
914 info_level);
915 eb = read_tree_block(fs_info->extent_root,
916 ref->parent, bsz, 0);
917 BUG_ON(!eb);
918 ret = find_extent_in_eb(eb, bytenr,
919 *extent_item_pos, &eie);
920 ref->inode_list = eie;
921 free_extent_buffer(eb);
923 ret = ulist_add_merge(refs, ref->parent,
924 (uintptr_t)ref->inode_list,
925 (u64 *)&eie, GFP_NOFS);
926 if (!ret && extent_item_pos) {
928 * we've recorded that parent, so we must extend
929 * its inode list here
931 BUG_ON(!eie);
932 while (eie->next)
933 eie = eie->next;
934 eie->next = ref->inode_list;
936 BUG_ON(ret < 0);
938 kfree(ref);
941 out:
942 btrfs_free_path(path);
943 while (!list_empty(&prefs)) {
944 ref = list_first_entry(&prefs, struct __prelim_ref, list);
945 list_del(&ref->list);
946 kfree(ref);
948 while (!list_empty(&prefs_delayed)) {
949 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
950 list);
951 list_del(&ref->list);
952 kfree(ref);
955 return ret;
958 static void free_leaf_list(struct ulist *blocks)
960 struct ulist_node *node = NULL;
961 struct extent_inode_elem *eie;
962 struct extent_inode_elem *eie_next;
963 struct ulist_iterator uiter;
965 ULIST_ITER_INIT(&uiter);
966 while ((node = ulist_next(blocks, &uiter))) {
967 if (!node->aux)
968 continue;
969 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
970 for (; eie; eie = eie_next) {
971 eie_next = eie->next;
972 kfree(eie);
974 node->aux = 0;
977 ulist_free(blocks);
981 * Finds all leafs with a reference to the specified combination of bytenr and
982 * offset. key_list_head will point to a list of corresponding keys (caller must
983 * free each list element). The leafs will be stored in the leafs ulist, which
984 * must be freed with ulist_free.
986 * returns 0 on success, <0 on error
988 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
989 struct btrfs_fs_info *fs_info, u64 bytenr,
990 u64 time_seq, struct ulist **leafs,
991 const u64 *extent_item_pos)
993 struct ulist *tmp;
994 int ret;
996 tmp = ulist_alloc(GFP_NOFS);
997 if (!tmp)
998 return -ENOMEM;
999 *leafs = ulist_alloc(GFP_NOFS);
1000 if (!*leafs) {
1001 ulist_free(tmp);
1002 return -ENOMEM;
1005 ret = find_parent_nodes(trans, fs_info, bytenr,
1006 time_seq, *leafs, tmp, extent_item_pos);
1007 ulist_free(tmp);
1009 if (ret < 0 && ret != -ENOENT) {
1010 free_leaf_list(*leafs);
1011 return ret;
1014 return 0;
1018 * walk all backrefs for a given extent to find all roots that reference this
1019 * extent. Walking a backref means finding all extents that reference this
1020 * extent and in turn walk the backrefs of those, too. Naturally this is a
1021 * recursive process, but here it is implemented in an iterative fashion: We
1022 * find all referencing extents for the extent in question and put them on a
1023 * list. In turn, we find all referencing extents for those, further appending
1024 * to the list. The way we iterate the list allows adding more elements after
1025 * the current while iterating. The process stops when we reach the end of the
1026 * list. Found roots are added to the roots list.
1028 * returns 0 on success, < 0 on error.
1030 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1031 struct btrfs_fs_info *fs_info, u64 bytenr,
1032 u64 time_seq, struct ulist **roots)
1034 struct ulist *tmp;
1035 struct ulist_node *node = NULL;
1036 struct ulist_iterator uiter;
1037 int ret;
1039 tmp = ulist_alloc(GFP_NOFS);
1040 if (!tmp)
1041 return -ENOMEM;
1042 *roots = ulist_alloc(GFP_NOFS);
1043 if (!*roots) {
1044 ulist_free(tmp);
1045 return -ENOMEM;
1048 ULIST_ITER_INIT(&uiter);
1049 while (1) {
1050 ret = find_parent_nodes(trans, fs_info, bytenr,
1051 time_seq, tmp, *roots, NULL);
1052 if (ret < 0 && ret != -ENOENT) {
1053 ulist_free(tmp);
1054 ulist_free(*roots);
1055 return ret;
1057 node = ulist_next(tmp, &uiter);
1058 if (!node)
1059 break;
1060 bytenr = node->val;
1063 ulist_free(tmp);
1064 return 0;
1068 static int __inode_info(u64 inum, u64 ioff, u8 key_type,
1069 struct btrfs_root *fs_root, struct btrfs_path *path,
1070 struct btrfs_key *found_key)
1072 int ret;
1073 struct btrfs_key key;
1074 struct extent_buffer *eb;
1076 key.type = key_type;
1077 key.objectid = inum;
1078 key.offset = ioff;
1080 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1081 if (ret < 0)
1082 return ret;
1084 eb = path->nodes[0];
1085 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1086 ret = btrfs_next_leaf(fs_root, path);
1087 if (ret)
1088 return ret;
1089 eb = path->nodes[0];
1092 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1093 if (found_key->type != key.type || found_key->objectid != key.objectid)
1094 return 1;
1096 return 0;
1100 * this makes the path point to (inum INODE_ITEM ioff)
1102 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1103 struct btrfs_path *path)
1105 struct btrfs_key key;
1106 return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
1107 &key);
1110 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1111 struct btrfs_path *path,
1112 struct btrfs_key *found_key)
1114 return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
1115 found_key);
1118 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1119 u64 start_off, struct btrfs_path *path,
1120 struct btrfs_inode_extref **ret_extref,
1121 u64 *found_off)
1123 int ret, slot;
1124 struct btrfs_key key;
1125 struct btrfs_key found_key;
1126 struct btrfs_inode_extref *extref;
1127 struct extent_buffer *leaf;
1128 unsigned long ptr;
1130 key.objectid = inode_objectid;
1131 btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1132 key.offset = start_off;
1134 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1135 if (ret < 0)
1136 return ret;
1138 while (1) {
1139 leaf = path->nodes[0];
1140 slot = path->slots[0];
1141 if (slot >= btrfs_header_nritems(leaf)) {
1143 * If the item at offset is not found,
1144 * btrfs_search_slot will point us to the slot
1145 * where it should be inserted. In our case
1146 * that will be the slot directly before the
1147 * next INODE_REF_KEY_V2 item. In the case
1148 * that we're pointing to the last slot in a
1149 * leaf, we must move one leaf over.
1151 ret = btrfs_next_leaf(root, path);
1152 if (ret) {
1153 if (ret >= 1)
1154 ret = -ENOENT;
1155 break;
1157 continue;
1160 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1163 * Check that we're still looking at an extended ref key for
1164 * this particular objectid. If we have different
1165 * objectid or type then there are no more to be found
1166 * in the tree and we can exit.
1168 ret = -ENOENT;
1169 if (found_key.objectid != inode_objectid)
1170 break;
1171 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1172 break;
1174 ret = 0;
1175 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1176 extref = (struct btrfs_inode_extref *)ptr;
1177 *ret_extref = extref;
1178 if (found_off)
1179 *found_off = found_key.offset;
1180 break;
1183 return ret;
1186 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1187 u32 name_len, unsigned long name_off,
1188 struct extent_buffer *eb_in, u64 parent,
1189 char *dest, u32 size)
1191 int slot;
1192 u64 next_inum;
1193 int ret;
1194 s64 bytes_left = ((s64)size) - 1;
1195 struct extent_buffer *eb = eb_in;
1196 struct btrfs_key found_key;
1197 int leave_spinning = path->leave_spinning;
1198 struct btrfs_inode_ref *iref;
1200 if (bytes_left >= 0)
1201 dest[bytes_left] = '\0';
1203 path->leave_spinning = 1;
1204 while (1) {
1205 bytes_left -= name_len;
1206 if (bytes_left >= 0)
1207 read_extent_buffer(eb, dest + bytes_left,
1208 name_off, name_len);
1209 if (eb != eb_in) {
1210 btrfs_tree_read_unlock_blocking(eb);
1211 free_extent_buffer(eb);
1213 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1214 if (ret > 0)
1215 ret = -ENOENT;
1216 if (ret)
1217 break;
1219 next_inum = found_key.offset;
1221 /* regular exit ahead */
1222 if (parent == next_inum)
1223 break;
1225 slot = path->slots[0];
1226 eb = path->nodes[0];
1227 /* make sure we can use eb after releasing the path */
1228 if (eb != eb_in) {
1229 atomic_inc(&eb->refs);
1230 btrfs_tree_read_lock(eb);
1231 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1233 btrfs_release_path(path);
1234 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1236 name_len = btrfs_inode_ref_name_len(eb, iref);
1237 name_off = (unsigned long)(iref + 1);
1239 parent = next_inum;
1240 --bytes_left;
1241 if (bytes_left >= 0)
1242 dest[bytes_left] = '/';
1245 btrfs_release_path(path);
1246 path->leave_spinning = leave_spinning;
1248 if (ret)
1249 return ERR_PTR(ret);
1251 return dest + bytes_left;
1255 * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
1256 * of the path are separated by '/' and the path is guaranteed to be
1257 * 0-terminated. the path is only given within the current file system.
1258 * Therefore, it never starts with a '/'. the caller is responsible to provide
1259 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1260 * the start point of the resulting string is returned. this pointer is within
1261 * dest, normally.
1262 * in case the path buffer would overflow, the pointer is decremented further
1263 * as if output was written to the buffer, though no more output is actually
1264 * generated. that way, the caller can determine how much space would be
1265 * required for the path to fit into the buffer. in that case, the returned
1266 * value will be smaller than dest. callers must check this!
1268 char *btrfs_iref_to_path(struct btrfs_root *fs_root,
1269 struct btrfs_path *path,
1270 struct btrfs_inode_ref *iref,
1271 struct extent_buffer *eb_in, u64 parent,
1272 char *dest, u32 size)
1274 return btrfs_ref_to_path(fs_root, path,
1275 btrfs_inode_ref_name_len(eb_in, iref),
1276 (unsigned long)(iref + 1),
1277 eb_in, parent, dest, size);
1281 * this makes the path point to (logical EXTENT_ITEM *)
1282 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1283 * tree blocks and <0 on error.
1285 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1286 struct btrfs_path *path, struct btrfs_key *found_key,
1287 u64 *flags_ret)
1289 int ret;
1290 u64 flags;
1291 u32 item_size;
1292 struct extent_buffer *eb;
1293 struct btrfs_extent_item *ei;
1294 struct btrfs_key key;
1296 key.type = BTRFS_EXTENT_ITEM_KEY;
1297 key.objectid = logical;
1298 key.offset = (u64)-1;
1300 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1301 if (ret < 0)
1302 return ret;
1303 ret = btrfs_previous_item(fs_info->extent_root, path,
1304 0, BTRFS_EXTENT_ITEM_KEY);
1305 if (ret < 0)
1306 return ret;
1308 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1309 if (found_key->type != BTRFS_EXTENT_ITEM_KEY ||
1310 found_key->objectid > logical ||
1311 found_key->objectid + found_key->offset <= logical) {
1312 pr_debug("logical %llu is not within any extent\n",
1313 (unsigned long long)logical);
1314 return -ENOENT;
1317 eb = path->nodes[0];
1318 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1319 BUG_ON(item_size < sizeof(*ei));
1321 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1322 flags = btrfs_extent_flags(eb, ei);
1324 pr_debug("logical %llu is at position %llu within the extent (%llu "
1325 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1326 (unsigned long long)logical,
1327 (unsigned long long)(logical - found_key->objectid),
1328 (unsigned long long)found_key->objectid,
1329 (unsigned long long)found_key->offset,
1330 (unsigned long long)flags, item_size);
1332 WARN_ON(!flags_ret);
1333 if (flags_ret) {
1334 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1335 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1336 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1337 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1338 else
1339 BUG_ON(1);
1340 return 0;
1343 return -EIO;
1347 * helper function to iterate extent inline refs. ptr must point to a 0 value
1348 * for the first call and may be modified. it is used to track state.
1349 * if more refs exist, 0 is returned and the next call to
1350 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1351 * next ref. after the last ref was processed, 1 is returned.
1352 * returns <0 on error
1354 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1355 struct btrfs_extent_item *ei, u32 item_size,
1356 struct btrfs_extent_inline_ref **out_eiref,
1357 int *out_type)
1359 unsigned long end;
1360 u64 flags;
1361 struct btrfs_tree_block_info *info;
1363 if (!*ptr) {
1364 /* first call */
1365 flags = btrfs_extent_flags(eb, ei);
1366 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1367 info = (struct btrfs_tree_block_info *)(ei + 1);
1368 *out_eiref =
1369 (struct btrfs_extent_inline_ref *)(info + 1);
1370 } else {
1371 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1373 *ptr = (unsigned long)*out_eiref;
1374 if ((void *)*ptr >= (void *)ei + item_size)
1375 return -ENOENT;
1378 end = (unsigned long)ei + item_size;
1379 *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1380 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1382 *ptr += btrfs_extent_inline_ref_size(*out_type);
1383 WARN_ON(*ptr > end);
1384 if (*ptr == end)
1385 return 1; /* last */
1387 return 0;
1391 * reads the tree block backref for an extent. tree level and root are returned
1392 * through out_level and out_root. ptr must point to a 0 value for the first
1393 * call and may be modified (see __get_extent_inline_ref comment).
1394 * returns 0 if data was provided, 1 if there was no more data to provide or
1395 * <0 on error.
1397 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1398 struct btrfs_extent_item *ei, u32 item_size,
1399 u64 *out_root, u8 *out_level)
1401 int ret;
1402 int type;
1403 struct btrfs_tree_block_info *info;
1404 struct btrfs_extent_inline_ref *eiref;
1406 if (*ptr == (unsigned long)-1)
1407 return 1;
1409 while (1) {
1410 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1411 &eiref, &type);
1412 if (ret < 0)
1413 return ret;
1415 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1416 type == BTRFS_SHARED_BLOCK_REF_KEY)
1417 break;
1419 if (ret == 1)
1420 return 1;
1423 /* we can treat both ref types equally here */
1424 info = (struct btrfs_tree_block_info *)(ei + 1);
1425 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1426 *out_level = btrfs_tree_block_level(eb, info);
1428 if (ret == 1)
1429 *ptr = (unsigned long)-1;
1431 return 0;
1434 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1435 u64 root, u64 extent_item_objectid,
1436 iterate_extent_inodes_t *iterate, void *ctx)
1438 struct extent_inode_elem *eie;
1439 int ret = 0;
1441 for (eie = inode_list; eie; eie = eie->next) {
1442 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1443 "root %llu\n", extent_item_objectid,
1444 eie->inum, eie->offset, root);
1445 ret = iterate(eie->inum, eie->offset, root, ctx);
1446 if (ret) {
1447 pr_debug("stopping iteration for %llu due to ret=%d\n",
1448 extent_item_objectid, ret);
1449 break;
1453 return ret;
1457 * calls iterate() for every inode that references the extent identified by
1458 * the given parameters.
1459 * when the iterator function returns a non-zero value, iteration stops.
1461 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1462 u64 extent_item_objectid, u64 extent_item_pos,
1463 int search_commit_root,
1464 iterate_extent_inodes_t *iterate, void *ctx)
1466 int ret;
1467 struct list_head data_refs = LIST_HEAD_INIT(data_refs);
1468 struct list_head shared_refs = LIST_HEAD_INIT(shared_refs);
1469 struct btrfs_trans_handle *trans;
1470 struct ulist *refs = NULL;
1471 struct ulist *roots = NULL;
1472 struct ulist_node *ref_node = NULL;
1473 struct ulist_node *root_node = NULL;
1474 struct seq_list tree_mod_seq_elem = {};
1475 struct ulist_iterator ref_uiter;
1476 struct ulist_iterator root_uiter;
1478 pr_debug("resolving all inodes for extent %llu\n",
1479 extent_item_objectid);
1481 if (search_commit_root) {
1482 trans = BTRFS_BACKREF_SEARCH_COMMIT_ROOT;
1483 } else {
1484 trans = btrfs_join_transaction(fs_info->extent_root);
1485 if (IS_ERR(trans))
1486 return PTR_ERR(trans);
1487 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1490 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1491 tree_mod_seq_elem.seq, &refs,
1492 &extent_item_pos);
1493 if (ret)
1494 goto out;
1496 ULIST_ITER_INIT(&ref_uiter);
1497 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1498 ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
1499 tree_mod_seq_elem.seq, &roots);
1500 if (ret)
1501 break;
1502 ULIST_ITER_INIT(&root_uiter);
1503 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1504 pr_debug("root %llu references leaf %llu, data list "
1505 "%#llx\n", root_node->val, ref_node->val,
1506 (long long)ref_node->aux);
1507 ret = iterate_leaf_refs((struct extent_inode_elem *)
1508 (uintptr_t)ref_node->aux,
1509 root_node->val,
1510 extent_item_objectid,
1511 iterate, ctx);
1513 ulist_free(roots);
1514 roots = NULL;
1517 free_leaf_list(refs);
1518 ulist_free(roots);
1519 out:
1520 if (!search_commit_root) {
1521 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1522 btrfs_end_transaction(trans, fs_info->extent_root);
1525 return ret;
1528 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1529 struct btrfs_path *path,
1530 iterate_extent_inodes_t *iterate, void *ctx)
1532 int ret;
1533 u64 extent_item_pos;
1534 u64 flags = 0;
1535 struct btrfs_key found_key;
1536 int search_commit_root = path->search_commit_root;
1538 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1539 btrfs_release_path(path);
1540 if (ret < 0)
1541 return ret;
1542 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1543 return -EINVAL;
1545 extent_item_pos = logical - found_key.objectid;
1546 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1547 extent_item_pos, search_commit_root,
1548 iterate, ctx);
1550 return ret;
1553 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1554 struct extent_buffer *eb, void *ctx);
1556 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1557 struct btrfs_path *path,
1558 iterate_irefs_t *iterate, void *ctx)
1560 int ret = 0;
1561 int slot;
1562 u32 cur;
1563 u32 len;
1564 u32 name_len;
1565 u64 parent = 0;
1566 int found = 0;
1567 struct extent_buffer *eb;
1568 struct btrfs_item *item;
1569 struct btrfs_inode_ref *iref;
1570 struct btrfs_key found_key;
1572 while (!ret) {
1573 path->leave_spinning = 1;
1574 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1575 &found_key);
1576 if (ret < 0)
1577 break;
1578 if (ret) {
1579 ret = found ? 0 : -ENOENT;
1580 break;
1582 ++found;
1584 parent = found_key.offset;
1585 slot = path->slots[0];
1586 eb = path->nodes[0];
1587 /* make sure we can use eb after releasing the path */
1588 atomic_inc(&eb->refs);
1589 btrfs_tree_read_lock(eb);
1590 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1591 btrfs_release_path(path);
1593 item = btrfs_item_nr(eb, slot);
1594 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1596 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1597 name_len = btrfs_inode_ref_name_len(eb, iref);
1598 /* path must be released before calling iterate()! */
1599 pr_debug("following ref at offset %u for inode %llu in "
1600 "tree %llu\n", cur,
1601 (unsigned long long)found_key.objectid,
1602 (unsigned long long)fs_root->objectid);
1603 ret = iterate(parent, name_len,
1604 (unsigned long)(iref + 1), eb, ctx);
1605 if (ret)
1606 break;
1607 len = sizeof(*iref) + name_len;
1608 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1610 btrfs_tree_read_unlock_blocking(eb);
1611 free_extent_buffer(eb);
1614 btrfs_release_path(path);
1616 return ret;
1619 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1620 struct btrfs_path *path,
1621 iterate_irefs_t *iterate, void *ctx)
1623 int ret;
1624 int slot;
1625 u64 offset = 0;
1626 u64 parent;
1627 int found = 0;
1628 struct extent_buffer *eb;
1629 struct btrfs_inode_extref *extref;
1630 struct extent_buffer *leaf;
1631 u32 item_size;
1632 u32 cur_offset;
1633 unsigned long ptr;
1635 while (1) {
1636 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1637 &offset);
1638 if (ret < 0)
1639 break;
1640 if (ret) {
1641 ret = found ? 0 : -ENOENT;
1642 break;
1644 ++found;
1646 slot = path->slots[0];
1647 eb = path->nodes[0];
1648 /* make sure we can use eb after releasing the path */
1649 atomic_inc(&eb->refs);
1651 btrfs_tree_read_lock(eb);
1652 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1653 btrfs_release_path(path);
1655 leaf = path->nodes[0];
1656 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1657 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1658 cur_offset = 0;
1660 while (cur_offset < item_size) {
1661 u32 name_len;
1663 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1664 parent = btrfs_inode_extref_parent(eb, extref);
1665 name_len = btrfs_inode_extref_name_len(eb, extref);
1666 ret = iterate(parent, name_len,
1667 (unsigned long)&extref->name, eb, ctx);
1668 if (ret)
1669 break;
1671 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1672 cur_offset += sizeof(*extref);
1674 btrfs_tree_read_unlock_blocking(eb);
1675 free_extent_buffer(eb);
1677 offset++;
1680 btrfs_release_path(path);
1682 return ret;
1685 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1686 struct btrfs_path *path, iterate_irefs_t *iterate,
1687 void *ctx)
1689 int ret;
1690 int found_refs = 0;
1692 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1693 if (!ret)
1694 ++found_refs;
1695 else if (ret != -ENOENT)
1696 return ret;
1698 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1699 if (ret == -ENOENT && found_refs)
1700 return 0;
1702 return ret;
1706 * returns 0 if the path could be dumped (probably truncated)
1707 * returns <0 in case of an error
1709 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1710 struct extent_buffer *eb, void *ctx)
1712 struct inode_fs_paths *ipath = ctx;
1713 char *fspath;
1714 char *fspath_min;
1715 int i = ipath->fspath->elem_cnt;
1716 const int s_ptr = sizeof(char *);
1717 u32 bytes_left;
1719 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1720 ipath->fspath->bytes_left - s_ptr : 0;
1722 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1723 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1724 name_off, eb, inum, fspath_min, bytes_left);
1725 if (IS_ERR(fspath))
1726 return PTR_ERR(fspath);
1728 if (fspath > fspath_min) {
1729 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1730 ++ipath->fspath->elem_cnt;
1731 ipath->fspath->bytes_left = fspath - fspath_min;
1732 } else {
1733 ++ipath->fspath->elem_missed;
1734 ipath->fspath->bytes_missing += fspath_min - fspath;
1735 ipath->fspath->bytes_left = 0;
1738 return 0;
1742 * this dumps all file system paths to the inode into the ipath struct, provided
1743 * is has been created large enough. each path is zero-terminated and accessed
1744 * from ipath->fspath->val[i].
1745 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1746 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1747 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1748 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1749 * have been needed to return all paths.
1751 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1753 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1754 inode_to_path, ipath);
1757 struct btrfs_data_container *init_data_container(u32 total_bytes)
1759 struct btrfs_data_container *data;
1760 size_t alloc_bytes;
1762 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1763 data = vmalloc(alloc_bytes);
1764 if (!data)
1765 return ERR_PTR(-ENOMEM);
1767 if (total_bytes >= sizeof(*data)) {
1768 data->bytes_left = total_bytes - sizeof(*data);
1769 data->bytes_missing = 0;
1770 } else {
1771 data->bytes_missing = sizeof(*data) - total_bytes;
1772 data->bytes_left = 0;
1775 data->elem_cnt = 0;
1776 data->elem_missed = 0;
1778 return data;
1782 * allocates space to return multiple file system paths for an inode.
1783 * total_bytes to allocate are passed, note that space usable for actual path
1784 * information will be total_bytes - sizeof(struct inode_fs_paths).
1785 * the returned pointer must be freed with free_ipath() in the end.
1787 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1788 struct btrfs_path *path)
1790 struct inode_fs_paths *ifp;
1791 struct btrfs_data_container *fspath;
1793 fspath = init_data_container(total_bytes);
1794 if (IS_ERR(fspath))
1795 return (void *)fspath;
1797 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1798 if (!ifp) {
1799 kfree(fspath);
1800 return ERR_PTR(-ENOMEM);
1803 ifp->btrfs_path = path;
1804 ifp->fspath = fspath;
1805 ifp->fs_root = fs_root;
1807 return ifp;
1810 void free_ipath(struct inode_fs_paths *ipath)
1812 if (!ipath)
1813 return;
1814 vfree(ipath->fspath);
1815 kfree(ipath);