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1/*
2 * Copyright (C) 2011 STRATO. All rights reserved.
3 *
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.
7 *
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.
12 *
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.
17 */
18
19#include <linux/vmalloc.h>
20#include <linux/rbtree.h>
21#include "ctree.h"
22#include "disk-io.h"
23#include "backref.h"
24#include "ulist.h"
25#include "transaction.h"
26#include "delayed-ref.h"
27#include "locking.h"
28
29/* Just an arbitrary number so we can be sure this happened */
30#define BACKREF_FOUND_SHARED 6
31
32struct extent_inode_elem {
33 u64 inum;
34 u64 offset;
35 struct extent_inode_elem *next;
36};
37
38/*
39 * ref_root is used as the root of the ref tree that hold a collection
40 * of unique references.
41 */
42struct ref_root {
43 struct rb_root rb_root;
44
45 /*
46 * The unique_refs represents the number of ref_nodes with a positive
47 * count stored in the tree. Even if a ref_node (the count is greater
48 * than one) is added, the unique_refs will only increase by one.
49 */
50 unsigned int unique_refs;
51};
52
53/* ref_node is used to store a unique reference to the ref tree. */
54struct ref_node {
55 struct rb_node rb_node;
56
57 /* For NORMAL_REF, otherwise all these fields should be set to 0 */
58 u64 root_id;
59 u64 object_id;
60 u64 offset;
61
62 /* For SHARED_REF, otherwise parent field should be set to 0 */
63 u64 parent;
64
65 /* Ref to the ref_mod of btrfs_delayed_ref_node */
66 int ref_mod;
67};
68
69/* Dynamically allocate and initialize a ref_root */
70static struct ref_root *ref_root_alloc(void)
71{
72 struct ref_root *ref_tree;
73
74 ref_tree = kmalloc(sizeof(*ref_tree), GFP_NOFS);
75 if (!ref_tree)
76 return NULL;
77
78 ref_tree->rb_root = RB_ROOT;
79 ref_tree->unique_refs = 0;
80
81 return ref_tree;
82}
83
84/* Free all nodes in the ref tree, and reinit ref_root */
85static void ref_root_fini(struct ref_root *ref_tree)
86{
87 struct ref_node *node;
88 struct rb_node *next;
89
90 while ((next = rb_first(&ref_tree->rb_root)) != NULL) {
91 node = rb_entry(next, struct ref_node, rb_node);
92 rb_erase(next, &ref_tree->rb_root);
93 kfree(node);
94 }
95
96 ref_tree->rb_root = RB_ROOT;
97 ref_tree->unique_refs = 0;
98}
99
100static void ref_root_free(struct ref_root *ref_tree)
101{
102 if (!ref_tree)
103 return;
104
105 ref_root_fini(ref_tree);
106 kfree(ref_tree);
107}
108
109/*
110 * Compare ref_node with (root_id, object_id, offset, parent)
111 *
112 * The function compares two ref_node a and b. It returns an integer less
113 * than, equal to, or greater than zero , respectively, to be less than, to
114 * equal, or be greater than b.
115 */
116static int ref_node_cmp(struct ref_node *a, struct ref_node *b)
117{
118 if (a->root_id < b->root_id)
119 return -1;
120 else if (a->root_id > b->root_id)
121 return 1;
122
123 if (a->object_id < b->object_id)
124 return -1;
125 else if (a->object_id > b->object_id)
126 return 1;
127
128 if (a->offset < b->offset)
129 return -1;
130 else if (a->offset > b->offset)
131 return 1;
132
133 if (a->parent < b->parent)
134 return -1;
135 else if (a->parent > b->parent)
136 return 1;
137
138 return 0;
139}
140
141/*
142 * Search ref_node with (root_id, object_id, offset, parent) in the tree
143 *
144 * if found, the pointer of the ref_node will be returned;
145 * if not found, NULL will be returned and pos will point to the rb_node for
146 * insert, pos_parent will point to pos'parent for insert;
147*/
148static struct ref_node *__ref_tree_search(struct ref_root *ref_tree,
149 struct rb_node ***pos,
150 struct rb_node **pos_parent,
151 u64 root_id, u64 object_id,
152 u64 offset, u64 parent)
153{
154 struct ref_node *cur = NULL;
155 struct ref_node entry;
156 int ret;
157
158 entry.root_id = root_id;
159 entry.object_id = object_id;
160 entry.offset = offset;
161 entry.parent = parent;
162
163 *pos = &ref_tree->rb_root.rb_node;
164
165 while (**pos) {
166 *pos_parent = **pos;
167 cur = rb_entry(*pos_parent, struct ref_node, rb_node);
168
169 ret = ref_node_cmp(cur, &entry);
170 if (ret > 0)
171 *pos = &(**pos)->rb_left;
172 else if (ret < 0)
173 *pos = &(**pos)->rb_right;
174 else
175 return cur;
176 }
177
178 return NULL;
179}
180
181/*
182 * Insert a ref_node to the ref tree
183 * @pos used for specifiy the position to insert
184 * @pos_parent for specifiy pos's parent
185 *
186 * success, return 0;
187 * ref_node already exists, return -EEXIST;
188*/
189static int ref_tree_insert(struct ref_root *ref_tree, struct rb_node **pos,
190 struct rb_node *pos_parent, struct ref_node *ins)
191{
192 struct rb_node **p = NULL;
193 struct rb_node *parent = NULL;
194 struct ref_node *cur = NULL;
195
196 if (!pos) {
197 cur = __ref_tree_search(ref_tree, &p, &parent, ins->root_id,
198 ins->object_id, ins->offset,
199 ins->parent);
200 if (cur)
201 return -EEXIST;
202 } else {
203 p = pos;
204 parent = pos_parent;
205 }
206
207 rb_link_node(&ins->rb_node, parent, p);
208 rb_insert_color(&ins->rb_node, &ref_tree->rb_root);
209
210 return 0;
211}
212
213/* Erase and free ref_node, caller should update ref_root->unique_refs */
214static void ref_tree_remove(struct ref_root *ref_tree, struct ref_node *node)
215{
216 rb_erase(&node->rb_node, &ref_tree->rb_root);
217 kfree(node);
218}
219
220/*
221 * Update ref_root->unique_refs
222 *
223 * Call __ref_tree_search
224 * 1. if ref_node doesn't exist, ref_tree_insert this node, and update
225 * ref_root->unique_refs:
226 * if ref_node->ref_mod > 0, ref_root->unique_refs++;
227 * if ref_node->ref_mod < 0, do noting;
228 *
229 * 2. if ref_node is found, then get origin ref_node->ref_mod, and update
230 * ref_node->ref_mod.
231 * if ref_node->ref_mod is equal to 0,then call ref_tree_remove
232 *
233 * according to origin_mod and new_mod, update ref_root->items
234 * +----------------+--------------+-------------+
235 * | |new_count <= 0|new_count > 0|
236 * +----------------+--------------+-------------+
237 * |origin_count < 0| 0 | 1 |
238 * +----------------+--------------+-------------+
239 * |origin_count > 0| -1 | 0 |
240 * +----------------+--------------+-------------+
241 *
242 * In case of allocation failure, -ENOMEM is returned and the ref_tree stays
243 * unaltered.
244 * Success, return 0
245 */
246static int ref_tree_add(struct ref_root *ref_tree, u64 root_id, u64 object_id,
247 u64 offset, u64 parent, int count)
248{
249 struct ref_node *node = NULL;
250 struct rb_node **pos = NULL;
251 struct rb_node *pos_parent = NULL;
252 int origin_count;
253 int ret;
254
255 if (!count)
256 return 0;
257
258 node = __ref_tree_search(ref_tree, &pos, &pos_parent, root_id,
259 object_id, offset, parent);
260 if (node == NULL) {
261 node = kmalloc(sizeof(*node), GFP_NOFS);
262 if (!node)
263 return -ENOMEM;
264
265 node->root_id = root_id;
266 node->object_id = object_id;
267 node->offset = offset;
268 node->parent = parent;
269 node->ref_mod = count;
270
271 ret = ref_tree_insert(ref_tree, pos, pos_parent, node);
272 ASSERT(!ret);
273 if (ret) {
274 kfree(node);
275 return ret;
276 }
277
278 ref_tree->unique_refs += node->ref_mod > 0 ? 1 : 0;
279
280 return 0;
281 }
282
283 origin_count = node->ref_mod;
284 node->ref_mod += count;
285
286 if (node->ref_mod > 0)
287 ref_tree->unique_refs += origin_count > 0 ? 0 : 1;
288 else if (node->ref_mod <= 0)
289 ref_tree->unique_refs += origin_count > 0 ? -1 : 0;
290
291 if (!node->ref_mod)
292 ref_tree_remove(ref_tree, node);
293
294 return 0;
295}
296
297static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
298 struct btrfs_file_extent_item *fi,
299 u64 extent_item_pos,
300 struct extent_inode_elem **eie)
301{
302 u64 offset = 0;
303 struct extent_inode_elem *e;
304
305 if (!btrfs_file_extent_compression(eb, fi) &&
306 !btrfs_file_extent_encryption(eb, fi) &&
307 !btrfs_file_extent_other_encoding(eb, fi)) {
308 u64 data_offset;
309 u64 data_len;
310
311 data_offset = btrfs_file_extent_offset(eb, fi);
312 data_len = btrfs_file_extent_num_bytes(eb, fi);
313
314 if (extent_item_pos < data_offset ||
315 extent_item_pos >= data_offset + data_len)
316 return 1;
317 offset = extent_item_pos - data_offset;
318 }
319
320 e = kmalloc(sizeof(*e), GFP_NOFS);
321 if (!e)
322 return -ENOMEM;
323
324 e->next = *eie;
325 e->inum = key->objectid;
326 e->offset = key->offset + offset;
327 *eie = e;
328
329 return 0;
330}
331
332static void free_inode_elem_list(struct extent_inode_elem *eie)
333{
334 struct extent_inode_elem *eie_next;
335
336 for (; eie; eie = eie_next) {
337 eie_next = eie->next;
338 kfree(eie);
339 }
340}
341
342static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
343 u64 extent_item_pos,
344 struct extent_inode_elem **eie)
345{
346 u64 disk_byte;
347 struct btrfs_key key;
348 struct btrfs_file_extent_item *fi;
349 int slot;
350 int nritems;
351 int extent_type;
352 int ret;
353
354 /*
355 * from the shared data ref, we only have the leaf but we need
356 * the key. thus, we must look into all items and see that we
357 * find one (some) with a reference to our extent item.
358 */
359 nritems = btrfs_header_nritems(eb);
360 for (slot = 0; slot < nritems; ++slot) {
361 btrfs_item_key_to_cpu(eb, &key, slot);
362 if (key.type != BTRFS_EXTENT_DATA_KEY)
363 continue;
364 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
365 extent_type = btrfs_file_extent_type(eb, fi);
366 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
367 continue;
368 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
369 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
370 if (disk_byte != wanted_disk_byte)
371 continue;
372
373 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
374 if (ret < 0)
375 return ret;
376 }
377
378 return 0;
379}
380
381/*
382 * this structure records all encountered refs on the way up to the root
383 */
384struct __prelim_ref {
385 struct list_head list;
386 u64 root_id;
387 struct btrfs_key key_for_search;
388 int level;
389 int count;
390 struct extent_inode_elem *inode_list;
391 u64 parent;
392 u64 wanted_disk_byte;
393};
394
395static struct kmem_cache *btrfs_prelim_ref_cache;
396
397int __init btrfs_prelim_ref_init(void)
398{
399 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
400 sizeof(struct __prelim_ref),
401 0,
402 SLAB_MEM_SPREAD,
403 NULL);
404 if (!btrfs_prelim_ref_cache)
405 return -ENOMEM;
406 return 0;
407}
408
409void btrfs_prelim_ref_exit(void)
410{
411 kmem_cache_destroy(btrfs_prelim_ref_cache);
412}
413
414/*
415 * the rules for all callers of this function are:
416 * - obtaining the parent is the goal
417 * - if you add a key, you must know that it is a correct key
418 * - if you cannot add the parent or a correct key, then we will look into the
419 * block later to set a correct key
420 *
421 * delayed refs
422 * ============
423 * backref type | shared | indirect | shared | indirect
424 * information | tree | tree | data | data
425 * --------------------+--------+----------+--------+----------
426 * parent logical | y | - | - | -
427 * key to resolve | - | y | y | y
428 * tree block logical | - | - | - | -
429 * root for resolving | y | y | y | y
430 *
431 * - column 1: we've the parent -> done
432 * - column 2, 3, 4: we use the key to find the parent
433 *
434 * on disk refs (inline or keyed)
435 * ==============================
436 * backref type | shared | indirect | shared | indirect
437 * information | tree | tree | data | data
438 * --------------------+--------+----------+--------+----------
439 * parent logical | y | - | y | -
440 * key to resolve | - | - | - | y
441 * tree block logical | y | y | y | y
442 * root for resolving | - | y | y | y
443 *
444 * - column 1, 3: we've the parent -> done
445 * - column 2: we take the first key from the block to find the parent
446 * (see __add_missing_keys)
447 * - column 4: we use the key to find the parent
448 *
449 * additional information that's available but not required to find the parent
450 * block might help in merging entries to gain some speed.
451 */
452
453static int __add_prelim_ref(struct list_head *head, u64 root_id,
454 struct btrfs_key *key, int level,
455 u64 parent, u64 wanted_disk_byte, int count,
456 gfp_t gfp_mask)
457{
458 struct __prelim_ref *ref;
459
460 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
461 return 0;
462
463 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
464 if (!ref)
465 return -ENOMEM;
466
467 ref->root_id = root_id;
468 if (key) {
469 ref->key_for_search = *key;
470 /*
471 * We can often find data backrefs with an offset that is too
472 * large (>= LLONG_MAX, maximum allowed file offset) due to
473 * underflows when subtracting a file's offset with the data
474 * offset of its corresponding extent data item. This can
475 * happen for example in the clone ioctl.
476 * So if we detect such case we set the search key's offset to
477 * zero to make sure we will find the matching file extent item
478 * at add_all_parents(), otherwise we will miss it because the
479 * offset taken form the backref is much larger then the offset
480 * of the file extent item. This can make us scan a very large
481 * number of file extent items, but at least it will not make
482 * us miss any.
483 * This is an ugly workaround for a behaviour that should have
484 * never existed, but it does and a fix for the clone ioctl
485 * would touch a lot of places, cause backwards incompatibility
486 * and would not fix the problem for extents cloned with older
487 * kernels.
488 */
489 if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY &&
490 ref->key_for_search.offset >= LLONG_MAX)
491 ref->key_for_search.offset = 0;
492 } else {
493 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
494 }
495
496 ref->inode_list = NULL;
497 ref->level = level;
498 ref->count = count;
499 ref->parent = parent;
500 ref->wanted_disk_byte = wanted_disk_byte;
501 list_add_tail(&ref->list, head);
502
503 return 0;
504}
505
506static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
507 struct ulist *parents, struct __prelim_ref *ref,
508 int level, u64 time_seq, const u64 *extent_item_pos,
509 u64 total_refs)
510{
511 int ret = 0;
512 int slot;
513 struct extent_buffer *eb;
514 struct btrfs_key key;
515 struct btrfs_key *key_for_search = &ref->key_for_search;
516 struct btrfs_file_extent_item *fi;
517 struct extent_inode_elem *eie = NULL, *old = NULL;
518 u64 disk_byte;
519 u64 wanted_disk_byte = ref->wanted_disk_byte;
520 u64 count = 0;
521
522 if (level != 0) {
523 eb = path->nodes[level];
524 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
525 if (ret < 0)
526 return ret;
527 return 0;
528 }
529
530 /*
531 * We normally enter this function with the path already pointing to
532 * the first item to check. But sometimes, we may enter it with
533 * slot==nritems. In that case, go to the next leaf before we continue.
534 */
535 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
536 if (time_seq == (u64)-1)
537 ret = btrfs_next_leaf(root, path);
538 else
539 ret = btrfs_next_old_leaf(root, path, time_seq);
540 }
541
542 while (!ret && count < total_refs) {
543 eb = path->nodes[0];
544 slot = path->slots[0];
545
546 btrfs_item_key_to_cpu(eb, &key, slot);
547
548 if (key.objectid != key_for_search->objectid ||
549 key.type != BTRFS_EXTENT_DATA_KEY)
550 break;
551
552 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
553 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
554
555 if (disk_byte == wanted_disk_byte) {
556 eie = NULL;
557 old = NULL;
558 count++;
559 if (extent_item_pos) {
560 ret = check_extent_in_eb(&key, eb, fi,
561 *extent_item_pos,
562 &eie);
563 if (ret < 0)
564 break;
565 }
566 if (ret > 0)
567 goto next;
568 ret = ulist_add_merge_ptr(parents, eb->start,
569 eie, (void **)&old, GFP_NOFS);
570 if (ret < 0)
571 break;
572 if (!ret && extent_item_pos) {
573 while (old->next)
574 old = old->next;
575 old->next = eie;
576 }
577 eie = NULL;
578 }
579next:
580 if (time_seq == (u64)-1)
581 ret = btrfs_next_item(root, path);
582 else
583 ret = btrfs_next_old_item(root, path, time_seq);
584 }
585
586 if (ret > 0)
587 ret = 0;
588 else if (ret < 0)
589 free_inode_elem_list(eie);
590 return ret;
591}
592
593/*
594 * resolve an indirect backref in the form (root_id, key, level)
595 * to a logical address
596 */
597static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
598 struct btrfs_path *path, u64 time_seq,
599 struct __prelim_ref *ref,
600 struct ulist *parents,
601 const u64 *extent_item_pos, u64 total_refs)
602{
603 struct btrfs_root *root;
604 struct btrfs_key root_key;
605 struct extent_buffer *eb;
606 int ret = 0;
607 int root_level;
608 int level = ref->level;
609 int index;
610
611 root_key.objectid = ref->root_id;
612 root_key.type = BTRFS_ROOT_ITEM_KEY;
613 root_key.offset = (u64)-1;
614
615 index = srcu_read_lock(&fs_info->subvol_srcu);
616
617 root = btrfs_get_fs_root(fs_info, &root_key, false);
618 if (IS_ERR(root)) {
619 srcu_read_unlock(&fs_info->subvol_srcu, index);
620 ret = PTR_ERR(root);
621 goto out;
622 }
623
624 if (btrfs_is_testing(fs_info)) {
625 srcu_read_unlock(&fs_info->subvol_srcu, index);
626 ret = -ENOENT;
627 goto out;
628 }
629
630 if (path->search_commit_root)
631 root_level = btrfs_header_level(root->commit_root);
632 else if (time_seq == (u64)-1)
633 root_level = btrfs_header_level(root->node);
634 else
635 root_level = btrfs_old_root_level(root, time_seq);
636
637 if (root_level + 1 == level) {
638 srcu_read_unlock(&fs_info->subvol_srcu, index);
639 goto out;
640 }
641
642 path->lowest_level = level;
643 if (time_seq == (u64)-1)
644 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path,
645 0, 0);
646 else
647 ret = btrfs_search_old_slot(root, &ref->key_for_search, path,
648 time_seq);
649
650 /* root node has been locked, we can release @subvol_srcu safely here */
651 srcu_read_unlock(&fs_info->subvol_srcu, index);
652
653 btrfs_debug(fs_info,
654 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
655 ref->root_id, level, ref->count, ret,
656 ref->key_for_search.objectid, ref->key_for_search.type,
657 ref->key_for_search.offset);
658 if (ret < 0)
659 goto out;
660
661 eb = path->nodes[level];
662 while (!eb) {
663 if (WARN_ON(!level)) {
664 ret = 1;
665 goto out;
666 }
667 level--;
668 eb = path->nodes[level];
669 }
670
671 ret = add_all_parents(root, path, parents, ref, level, time_seq,
672 extent_item_pos, total_refs);
673out:
674 path->lowest_level = 0;
675 btrfs_release_path(path);
676 return ret;
677}
678
679/*
680 * resolve all indirect backrefs from the list
681 */
682static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
683 struct btrfs_path *path, u64 time_seq,
684 struct list_head *head,
685 const u64 *extent_item_pos, u64 total_refs,
686 u64 root_objectid)
687{
688 int err;
689 int ret = 0;
690 struct __prelim_ref *ref;
691 struct __prelim_ref *ref_safe;
692 struct __prelim_ref *new_ref;
693 struct ulist *parents;
694 struct ulist_node *node;
695 struct ulist_iterator uiter;
696
697 parents = ulist_alloc(GFP_NOFS);
698 if (!parents)
699 return -ENOMEM;
700
701 /*
702 * _safe allows us to insert directly after the current item without
703 * iterating over the newly inserted items.
704 * we're also allowed to re-assign ref during iteration.
705 */
706 list_for_each_entry_safe(ref, ref_safe, head, list) {
707 if (ref->parent) /* already direct */
708 continue;
709 if (ref->count == 0)
710 continue;
711 if (root_objectid && ref->root_id != root_objectid) {
712 ret = BACKREF_FOUND_SHARED;
713 goto out;
714 }
715 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
716 parents, extent_item_pos,
717 total_refs);
718 /*
719 * we can only tolerate ENOENT,otherwise,we should catch error
720 * and return directly.
721 */
722 if (err == -ENOENT) {
723 continue;
724 } else if (err) {
725 ret = err;
726 goto out;
727 }
728
729 /* we put the first parent into the ref at hand */
730 ULIST_ITER_INIT(&uiter);
731 node = ulist_next(parents, &uiter);
732 ref->parent = node ? node->val : 0;
733 ref->inode_list = node ?
734 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
735
736 /* additional parents require new refs being added here */
737 while ((node = ulist_next(parents, &uiter))) {
738 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
739 GFP_NOFS);
740 if (!new_ref) {
741 ret = -ENOMEM;
742 goto out;
743 }
744 memcpy(new_ref, ref, sizeof(*ref));
745 new_ref->parent = node->val;
746 new_ref->inode_list = (struct extent_inode_elem *)
747 (uintptr_t)node->aux;
748 list_add(&new_ref->list, &ref->list);
749 }
750 ulist_reinit(parents);
751 }
752out:
753 ulist_free(parents);
754 return ret;
755}
756
757static inline int ref_for_same_block(struct __prelim_ref *ref1,
758 struct __prelim_ref *ref2)
759{
760 if (ref1->level != ref2->level)
761 return 0;
762 if (ref1->root_id != ref2->root_id)
763 return 0;
764 if (ref1->key_for_search.type != ref2->key_for_search.type)
765 return 0;
766 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
767 return 0;
768 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
769 return 0;
770 if (ref1->parent != ref2->parent)
771 return 0;
772
773 return 1;
774}
775
776/*
777 * read tree blocks and add keys where required.
778 */
779static int __add_missing_keys(struct btrfs_fs_info *fs_info,
780 struct list_head *head)
781{
782 struct __prelim_ref *ref;
783 struct extent_buffer *eb;
784
785 list_for_each_entry(ref, head, list) {
786 if (ref->parent)
787 continue;
788 if (ref->key_for_search.type)
789 continue;
790 BUG_ON(!ref->wanted_disk_byte);
791 eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0);
792 if (IS_ERR(eb)) {
793 return PTR_ERR(eb);
794 } else if (!extent_buffer_uptodate(eb)) {
795 free_extent_buffer(eb);
796 return -EIO;
797 }
798 btrfs_tree_read_lock(eb);
799 if (btrfs_header_level(eb) == 0)
800 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
801 else
802 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
803 btrfs_tree_read_unlock(eb);
804 free_extent_buffer(eb);
805 }
806 return 0;
807}
808
809/*
810 * merge backrefs and adjust counts accordingly
811 *
812 * mode = 1: merge identical keys, if key is set
813 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
814 * additionally, we could even add a key range for the blocks we
815 * looked into to merge even more (-> replace unresolved refs by those
816 * having a parent).
817 * mode = 2: merge identical parents
818 */
819static void __merge_refs(struct list_head *head, int mode)
820{
821 struct __prelim_ref *pos1;
822
823 list_for_each_entry(pos1, head, list) {
824 struct __prelim_ref *pos2 = pos1, *tmp;
825
826 list_for_each_entry_safe_continue(pos2, tmp, head, list) {
827 struct __prelim_ref *ref1 = pos1, *ref2 = pos2;
828 struct extent_inode_elem *eie;
829
830 if (!ref_for_same_block(ref1, ref2))
831 continue;
832 if (mode == 1) {
833 if (!ref1->parent && ref2->parent)
834 swap(ref1, ref2);
835 } else {
836 if (ref1->parent != ref2->parent)
837 continue;
838 }
839
840 eie = ref1->inode_list;
841 while (eie && eie->next)
842 eie = eie->next;
843 if (eie)
844 eie->next = ref2->inode_list;
845 else
846 ref1->inode_list = ref2->inode_list;
847 ref1->count += ref2->count;
848
849 list_del(&ref2->list);
850 kmem_cache_free(btrfs_prelim_ref_cache, ref2);
851 cond_resched();
852 }
853
854 }
855}
856
857/*
858 * add all currently queued delayed refs from this head whose seq nr is
859 * smaller or equal that seq to the list
860 */
861static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
862 struct list_head *prefs, u64 *total_refs,
863 u64 inum)
864{
865 struct btrfs_delayed_ref_node *node;
866 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
867 struct btrfs_key key;
868 struct btrfs_key op_key = {0};
869 int sgn;
870 int ret = 0;
871
872 if (extent_op && extent_op->update_key)
873 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
874
875 spin_lock(&head->lock);
876 list_for_each_entry(node, &head->ref_list, list) {
877 if (node->seq > seq)
878 continue;
879
880 switch (node->action) {
881 case BTRFS_ADD_DELAYED_EXTENT:
882 case BTRFS_UPDATE_DELAYED_HEAD:
883 WARN_ON(1);
884 continue;
885 case BTRFS_ADD_DELAYED_REF:
886 sgn = 1;
887 break;
888 case BTRFS_DROP_DELAYED_REF:
889 sgn = -1;
890 break;
891 default:
892 BUG_ON(1);
893 }
894 *total_refs += (node->ref_mod * sgn);
895 switch (node->type) {
896 case BTRFS_TREE_BLOCK_REF_KEY: {
897 struct btrfs_delayed_tree_ref *ref;
898
899 ref = btrfs_delayed_node_to_tree_ref(node);
900 ret = __add_prelim_ref(prefs, ref->root, &op_key,
901 ref->level + 1, 0, node->bytenr,
902 node->ref_mod * sgn, GFP_ATOMIC);
903 break;
904 }
905 case BTRFS_SHARED_BLOCK_REF_KEY: {
906 struct btrfs_delayed_tree_ref *ref;
907
908 ref = btrfs_delayed_node_to_tree_ref(node);
909 ret = __add_prelim_ref(prefs, 0, NULL,
910 ref->level + 1, ref->parent,
911 node->bytenr,
912 node->ref_mod * sgn, GFP_ATOMIC);
913 break;
914 }
915 case BTRFS_EXTENT_DATA_REF_KEY: {
916 struct btrfs_delayed_data_ref *ref;
917 ref = btrfs_delayed_node_to_data_ref(node);
918
919 key.objectid = ref->objectid;
920 key.type = BTRFS_EXTENT_DATA_KEY;
921 key.offset = ref->offset;
922
923 /*
924 * Found a inum that doesn't match our known inum, we
925 * know it's shared.
926 */
927 if (inum && ref->objectid != inum) {
928 ret = BACKREF_FOUND_SHARED;
929 break;
930 }
931
932 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
933 node->bytenr,
934 node->ref_mod * sgn, GFP_ATOMIC);
935 break;
936 }
937 case BTRFS_SHARED_DATA_REF_KEY: {
938 struct btrfs_delayed_data_ref *ref;
939
940 ref = btrfs_delayed_node_to_data_ref(node);
941 ret = __add_prelim_ref(prefs, 0, NULL, 0,
942 ref->parent, node->bytenr,
943 node->ref_mod * sgn, GFP_ATOMIC);
944 break;
945 }
946 default:
947 WARN_ON(1);
948 }
949 if (ret)
950 break;
951 }
952 spin_unlock(&head->lock);
953 return ret;
954}
955
956/*
957 * add all inline backrefs for bytenr to the list
958 */
959static int __add_inline_refs(struct btrfs_fs_info *fs_info,
960 struct btrfs_path *path, u64 bytenr,
961 int *info_level, struct list_head *prefs,
962 struct ref_root *ref_tree,
963 u64 *total_refs, u64 inum)
964{
965 int ret = 0;
966 int slot;
967 struct extent_buffer *leaf;
968 struct btrfs_key key;
969 struct btrfs_key found_key;
970 unsigned long ptr;
971 unsigned long end;
972 struct btrfs_extent_item *ei;
973 u64 flags;
974 u64 item_size;
975
976 /*
977 * enumerate all inline refs
978 */
979 leaf = path->nodes[0];
980 slot = path->slots[0];
981
982 item_size = btrfs_item_size_nr(leaf, slot);
983 BUG_ON(item_size < sizeof(*ei));
984
985 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
986 flags = btrfs_extent_flags(leaf, ei);
987 *total_refs += btrfs_extent_refs(leaf, ei);
988 btrfs_item_key_to_cpu(leaf, &found_key, slot);
989
990 ptr = (unsigned long)(ei + 1);
991 end = (unsigned long)ei + item_size;
992
993 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
994 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
995 struct btrfs_tree_block_info *info;
996
997 info = (struct btrfs_tree_block_info *)ptr;
998 *info_level = btrfs_tree_block_level(leaf, info);
999 ptr += sizeof(struct btrfs_tree_block_info);
1000 BUG_ON(ptr > end);
1001 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
1002 *info_level = found_key.offset;
1003 } else {
1004 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
1005 }
1006
1007 while (ptr < end) {
1008 struct btrfs_extent_inline_ref *iref;
1009 u64 offset;
1010 int type;
1011
1012 iref = (struct btrfs_extent_inline_ref *)ptr;
1013 type = btrfs_extent_inline_ref_type(leaf, iref);
1014 offset = btrfs_extent_inline_ref_offset(leaf, iref);
1015
1016 switch (type) {
1017 case BTRFS_SHARED_BLOCK_REF_KEY:
1018 ret = __add_prelim_ref(prefs, 0, NULL,
1019 *info_level + 1, offset,
1020 bytenr, 1, GFP_NOFS);
1021 break;
1022 case BTRFS_SHARED_DATA_REF_KEY: {
1023 struct btrfs_shared_data_ref *sdref;
1024 int count;
1025
1026 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
1027 count = btrfs_shared_data_ref_count(leaf, sdref);
1028 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
1029 bytenr, count, GFP_NOFS);
1030 if (ref_tree) {
1031 if (!ret)
1032 ret = ref_tree_add(ref_tree, 0, 0, 0,
1033 bytenr, count);
1034 if (!ret && ref_tree->unique_refs > 1)
1035 ret = BACKREF_FOUND_SHARED;
1036 }
1037 break;
1038 }
1039 case BTRFS_TREE_BLOCK_REF_KEY:
1040 ret = __add_prelim_ref(prefs, offset, NULL,
1041 *info_level + 1, 0,
1042 bytenr, 1, GFP_NOFS);
1043 break;
1044 case BTRFS_EXTENT_DATA_REF_KEY: {
1045 struct btrfs_extent_data_ref *dref;
1046 int count;
1047 u64 root;
1048
1049 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1050 count = btrfs_extent_data_ref_count(leaf, dref);
1051 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1052 dref);
1053 key.type = BTRFS_EXTENT_DATA_KEY;
1054 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1055
1056 if (inum && key.objectid != inum) {
1057 ret = BACKREF_FOUND_SHARED;
1058 break;
1059 }
1060
1061 root = btrfs_extent_data_ref_root(leaf, dref);
1062 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
1063 bytenr, count, GFP_NOFS);
1064 if (ref_tree) {
1065 if (!ret)
1066 ret = ref_tree_add(ref_tree, root,
1067 key.objectid,
1068 key.offset, 0,
1069 count);
1070 if (!ret && ref_tree->unique_refs > 1)
1071 ret = BACKREF_FOUND_SHARED;
1072 }
1073 break;
1074 }
1075 default:
1076 WARN_ON(1);
1077 }
1078 if (ret)
1079 return ret;
1080 ptr += btrfs_extent_inline_ref_size(type);
1081 }
1082
1083 return 0;
1084}
1085
1086/*
1087 * add all non-inline backrefs for bytenr to the list
1088 */
1089static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
1090 struct btrfs_path *path, u64 bytenr,
1091 int info_level, struct list_head *prefs,
1092 struct ref_root *ref_tree, u64 inum)
1093{
1094 struct btrfs_root *extent_root = fs_info->extent_root;
1095 int ret;
1096 int slot;
1097 struct extent_buffer *leaf;
1098 struct btrfs_key key;
1099
1100 while (1) {
1101 ret = btrfs_next_item(extent_root, path);
1102 if (ret < 0)
1103 break;
1104 if (ret) {
1105 ret = 0;
1106 break;
1107 }
1108
1109 slot = path->slots[0];
1110 leaf = path->nodes[0];
1111 btrfs_item_key_to_cpu(leaf, &key, slot);
1112
1113 if (key.objectid != bytenr)
1114 break;
1115 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1116 continue;
1117 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1118 break;
1119
1120 switch (key.type) {
1121 case BTRFS_SHARED_BLOCK_REF_KEY:
1122 ret = __add_prelim_ref(prefs, 0, NULL,
1123 info_level + 1, key.offset,
1124 bytenr, 1, GFP_NOFS);
1125 break;
1126 case BTRFS_SHARED_DATA_REF_KEY: {
1127 struct btrfs_shared_data_ref *sdref;
1128 int count;
1129
1130 sdref = btrfs_item_ptr(leaf, slot,
1131 struct btrfs_shared_data_ref);
1132 count = btrfs_shared_data_ref_count(leaf, sdref);
1133 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
1134 bytenr, count, GFP_NOFS);
1135 if (ref_tree) {
1136 if (!ret)
1137 ret = ref_tree_add(ref_tree, 0, 0, 0,
1138 bytenr, count);
1139 if (!ret && ref_tree->unique_refs > 1)
1140 ret = BACKREF_FOUND_SHARED;
1141 }
1142 break;
1143 }
1144 case BTRFS_TREE_BLOCK_REF_KEY:
1145 ret = __add_prelim_ref(prefs, key.offset, NULL,
1146 info_level + 1, 0,
1147 bytenr, 1, GFP_NOFS);
1148 break;
1149 case BTRFS_EXTENT_DATA_REF_KEY: {
1150 struct btrfs_extent_data_ref *dref;
1151 int count;
1152 u64 root;
1153
1154 dref = btrfs_item_ptr(leaf, slot,
1155 struct btrfs_extent_data_ref);
1156 count = btrfs_extent_data_ref_count(leaf, dref);
1157 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1158 dref);
1159 key.type = BTRFS_EXTENT_DATA_KEY;
1160 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1161
1162 if (inum && key.objectid != inum) {
1163 ret = BACKREF_FOUND_SHARED;
1164 break;
1165 }
1166
1167 root = btrfs_extent_data_ref_root(leaf, dref);
1168 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
1169 bytenr, count, GFP_NOFS);
1170 if (ref_tree) {
1171 if (!ret)
1172 ret = ref_tree_add(ref_tree, root,
1173 key.objectid,
1174 key.offset, 0,
1175 count);
1176 if (!ret && ref_tree->unique_refs > 1)
1177 ret = BACKREF_FOUND_SHARED;
1178 }
1179 break;
1180 }
1181 default:
1182 WARN_ON(1);
1183 }
1184 if (ret)
1185 return ret;
1186
1187 }
1188
1189 return ret;
1190}
1191
1192/*
1193 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1194 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1195 * indirect refs to their parent bytenr.
1196 * When roots are found, they're added to the roots list
1197 *
1198 * NOTE: This can return values > 0
1199 *
1200 * If time_seq is set to (u64)-1, it will not search delayed_refs, and behave
1201 * much like trans == NULL case, the difference only lies in it will not
1202 * commit root.
1203 * The special case is for qgroup to search roots in commit_transaction().
1204 *
1205 * If check_shared is set to 1, any extent has more than one ref item, will
1206 * be returned BACKREF_FOUND_SHARED immediately.
1207 *
1208 * FIXME some caching might speed things up
1209 */
1210static int find_parent_nodes(struct btrfs_trans_handle *trans,
1211 struct btrfs_fs_info *fs_info, u64 bytenr,
1212 u64 time_seq, struct ulist *refs,
1213 struct ulist *roots, const u64 *extent_item_pos,
1214 u64 root_objectid, u64 inum, int check_shared)
1215{
1216 struct btrfs_key key;
1217 struct btrfs_path *path;
1218 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1219 struct btrfs_delayed_ref_head *head;
1220 int info_level = 0;
1221 int ret;
1222 struct list_head prefs_delayed;
1223 struct list_head prefs;
1224 struct __prelim_ref *ref;
1225 struct extent_inode_elem *eie = NULL;
1226 struct ref_root *ref_tree = NULL;
1227 u64 total_refs = 0;
1228
1229 INIT_LIST_HEAD(&prefs);
1230 INIT_LIST_HEAD(&prefs_delayed);
1231
1232 key.objectid = bytenr;
1233 key.offset = (u64)-1;
1234 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1235 key.type = BTRFS_METADATA_ITEM_KEY;
1236 else
1237 key.type = BTRFS_EXTENT_ITEM_KEY;
1238
1239 path = btrfs_alloc_path();
1240 if (!path)
1241 return -ENOMEM;
1242 if (!trans) {
1243 path->search_commit_root = 1;
1244 path->skip_locking = 1;
1245 }
1246
1247 if (time_seq == (u64)-1)
1248 path->skip_locking = 1;
1249
1250 /*
1251 * grab both a lock on the path and a lock on the delayed ref head.
1252 * We need both to get a consistent picture of how the refs look
1253 * at a specified point in time
1254 */
1255again:
1256 head = NULL;
1257
1258 if (check_shared) {
1259 if (!ref_tree) {
1260 ref_tree = ref_root_alloc();
1261 if (!ref_tree) {
1262 ret = -ENOMEM;
1263 goto out;
1264 }
1265 } else {
1266 ref_root_fini(ref_tree);
1267 }
1268 }
1269
1270 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
1271 if (ret < 0)
1272 goto out;
1273 BUG_ON(ret == 0);
1274
1275#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1276 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1277 time_seq != (u64)-1) {
1278#else
1279 if (trans && time_seq != (u64)-1) {
1280#endif
1281 /*
1282 * look if there are updates for this ref queued and lock the
1283 * head
1284 */
1285 delayed_refs = &trans->transaction->delayed_refs;
1286 spin_lock(&delayed_refs->lock);
1287 head = btrfs_find_delayed_ref_head(trans, bytenr);
1288 if (head) {
1289 if (!mutex_trylock(&head->mutex)) {
1290 atomic_inc(&head->node.refs);
1291 spin_unlock(&delayed_refs->lock);
1292
1293 btrfs_release_path(path);
1294
1295 /*
1296 * Mutex was contended, block until it's
1297 * released and try again
1298 */
1299 mutex_lock(&head->mutex);
1300 mutex_unlock(&head->mutex);
1301 btrfs_put_delayed_ref(&head->node);
1302 goto again;
1303 }
1304 spin_unlock(&delayed_refs->lock);
1305 ret = __add_delayed_refs(head, time_seq,
1306 &prefs_delayed, &total_refs,
1307 inum);
1308 mutex_unlock(&head->mutex);
1309 if (ret)
1310 goto out;
1311 } else {
1312 spin_unlock(&delayed_refs->lock);
1313 }
1314
1315 if (check_shared && !list_empty(&prefs_delayed)) {
1316 /*
1317 * Add all delay_ref to the ref_tree and check if there
1318 * are multiple ref items added.
1319 */
1320 list_for_each_entry(ref, &prefs_delayed, list) {
1321 if (ref->key_for_search.type) {
1322 ret = ref_tree_add(ref_tree,
1323 ref->root_id,
1324 ref->key_for_search.objectid,
1325 ref->key_for_search.offset,
1326 0, ref->count);
1327 if (ret)
1328 goto out;
1329 } else {
1330 ret = ref_tree_add(ref_tree, 0, 0, 0,
1331 ref->parent, ref->count);
1332 if (ret)
1333 goto out;
1334 }
1335
1336 }
1337
1338 if (ref_tree->unique_refs > 1) {
1339 ret = BACKREF_FOUND_SHARED;
1340 goto out;
1341 }
1342
1343 }
1344 }
1345
1346 if (path->slots[0]) {
1347 struct extent_buffer *leaf;
1348 int slot;
1349
1350 path->slots[0]--;
1351 leaf = path->nodes[0];
1352 slot = path->slots[0];
1353 btrfs_item_key_to_cpu(leaf, &key, slot);
1354 if (key.objectid == bytenr &&
1355 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1356 key.type == BTRFS_METADATA_ITEM_KEY)) {
1357 ret = __add_inline_refs(fs_info, path, bytenr,
1358 &info_level, &prefs,
1359 ref_tree, &total_refs,
1360 inum);
1361 if (ret)
1362 goto out;
1363 ret = __add_keyed_refs(fs_info, path, bytenr,
1364 info_level, &prefs,
1365 ref_tree, inum);
1366 if (ret)
1367 goto out;
1368 }
1369 }
1370 btrfs_release_path(path);
1371
1372 list_splice_init(&prefs_delayed, &prefs);
1373
1374 ret = __add_missing_keys(fs_info, &prefs);
1375 if (ret)
1376 goto out;
1377
1378 __merge_refs(&prefs, 1);
1379
1380 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
1381 extent_item_pos, total_refs,
1382 root_objectid);
1383 if (ret)
1384 goto out;
1385
1386 __merge_refs(&prefs, 2);
1387
1388 while (!list_empty(&prefs)) {
1389 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1390 WARN_ON(ref->count < 0);
1391 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1392 if (root_objectid && ref->root_id != root_objectid) {
1393 ret = BACKREF_FOUND_SHARED;
1394 goto out;
1395 }
1396
1397 /* no parent == root of tree */
1398 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1399 if (ret < 0)
1400 goto out;
1401 }
1402 if (ref->count && ref->parent) {
1403 if (extent_item_pos && !ref->inode_list &&
1404 ref->level == 0) {
1405 struct extent_buffer *eb;
1406
1407 eb = read_tree_block(fs_info, ref->parent, 0);
1408 if (IS_ERR(eb)) {
1409 ret = PTR_ERR(eb);
1410 goto out;
1411 } else if (!extent_buffer_uptodate(eb)) {
1412 free_extent_buffer(eb);
1413 ret = -EIO;
1414 goto out;
1415 }
1416 btrfs_tree_read_lock(eb);
1417 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1418 ret = find_extent_in_eb(eb, bytenr,
1419 *extent_item_pos, &eie);
1420 btrfs_tree_read_unlock_blocking(eb);
1421 free_extent_buffer(eb);
1422 if (ret < 0)
1423 goto out;
1424 ref->inode_list = eie;
1425 }
1426 ret = ulist_add_merge_ptr(refs, ref->parent,
1427 ref->inode_list,
1428 (void **)&eie, GFP_NOFS);
1429 if (ret < 0)
1430 goto out;
1431 if (!ret && extent_item_pos) {
1432 /*
1433 * we've recorded that parent, so we must extend
1434 * its inode list here
1435 */
1436 BUG_ON(!eie);
1437 while (eie->next)
1438 eie = eie->next;
1439 eie->next = ref->inode_list;
1440 }
1441 eie = NULL;
1442 }
1443 list_del(&ref->list);
1444 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1445 }
1446
1447out:
1448 btrfs_free_path(path);
1449 ref_root_free(ref_tree);
1450 while (!list_empty(&prefs)) {
1451 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1452 list_del(&ref->list);
1453 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1454 }
1455 while (!list_empty(&prefs_delayed)) {
1456 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
1457 list);
1458 list_del(&ref->list);
1459 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1460 }
1461 if (ret < 0)
1462 free_inode_elem_list(eie);
1463 return ret;
1464}
1465
1466static void free_leaf_list(struct ulist *blocks)
1467{
1468 struct ulist_node *node = NULL;
1469 struct extent_inode_elem *eie;
1470 struct ulist_iterator uiter;
1471
1472 ULIST_ITER_INIT(&uiter);
1473 while ((node = ulist_next(blocks, &uiter))) {
1474 if (!node->aux)
1475 continue;
1476 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1477 free_inode_elem_list(eie);
1478 node->aux = 0;
1479 }
1480
1481 ulist_free(blocks);
1482}
1483
1484/*
1485 * Finds all leafs with a reference to the specified combination of bytenr and
1486 * offset. key_list_head will point to a list of corresponding keys (caller must
1487 * free each list element). The leafs will be stored in the leafs ulist, which
1488 * must be freed with ulist_free.
1489 *
1490 * returns 0 on success, <0 on error
1491 */
1492static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1493 struct btrfs_fs_info *fs_info, u64 bytenr,
1494 u64 time_seq, struct ulist **leafs,
1495 const u64 *extent_item_pos)
1496{
1497 int ret;
1498
1499 *leafs = ulist_alloc(GFP_NOFS);
1500 if (!*leafs)
1501 return -ENOMEM;
1502
1503 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1504 *leafs, NULL, extent_item_pos, 0, 0, 0);
1505 if (ret < 0 && ret != -ENOENT) {
1506 free_leaf_list(*leafs);
1507 return ret;
1508 }
1509
1510 return 0;
1511}
1512
1513/*
1514 * walk all backrefs for a given extent to find all roots that reference this
1515 * extent. Walking a backref means finding all extents that reference this
1516 * extent and in turn walk the backrefs of those, too. Naturally this is a
1517 * recursive process, but here it is implemented in an iterative fashion: We
1518 * find all referencing extents for the extent in question and put them on a
1519 * list. In turn, we find all referencing extents for those, further appending
1520 * to the list. The way we iterate the list allows adding more elements after
1521 * the current while iterating. The process stops when we reach the end of the
1522 * list. Found roots are added to the roots list.
1523 *
1524 * returns 0 on success, < 0 on error.
1525 */
1526static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1527 struct btrfs_fs_info *fs_info, u64 bytenr,
1528 u64 time_seq, struct ulist **roots)
1529{
1530 struct ulist *tmp;
1531 struct ulist_node *node = NULL;
1532 struct ulist_iterator uiter;
1533 int ret;
1534
1535 tmp = ulist_alloc(GFP_NOFS);
1536 if (!tmp)
1537 return -ENOMEM;
1538 *roots = ulist_alloc(GFP_NOFS);
1539 if (!*roots) {
1540 ulist_free(tmp);
1541 return -ENOMEM;
1542 }
1543
1544 ULIST_ITER_INIT(&uiter);
1545 while (1) {
1546 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1547 tmp, *roots, NULL, 0, 0, 0);
1548 if (ret < 0 && ret != -ENOENT) {
1549 ulist_free(tmp);
1550 ulist_free(*roots);
1551 return ret;
1552 }
1553 node = ulist_next(tmp, &uiter);
1554 if (!node)
1555 break;
1556 bytenr = node->val;
1557 cond_resched();
1558 }
1559
1560 ulist_free(tmp);
1561 return 0;
1562}
1563
1564int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1565 struct btrfs_fs_info *fs_info, u64 bytenr,
1566 u64 time_seq, struct ulist **roots)
1567{
1568 int ret;
1569
1570 if (!trans)
1571 down_read(&fs_info->commit_root_sem);
1572 ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
1573 if (!trans)
1574 up_read(&fs_info->commit_root_sem);
1575 return ret;
1576}
1577
1578/**
1579 * btrfs_check_shared - tell us whether an extent is shared
1580 *
1581 * @trans: optional trans handle
1582 *
1583 * btrfs_check_shared uses the backref walking code but will short
1584 * circuit as soon as it finds a root or inode that doesn't match the
1585 * one passed in. This provides a significant performance benefit for
1586 * callers (such as fiemap) which want to know whether the extent is
1587 * shared but do not need a ref count.
1588 *
1589 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1590 */
1591int btrfs_check_shared(struct btrfs_trans_handle *trans,
1592 struct btrfs_fs_info *fs_info, u64 root_objectid,
1593 u64 inum, u64 bytenr)
1594{
1595 struct ulist *tmp = NULL;
1596 struct ulist *roots = NULL;
1597 struct ulist_iterator uiter;
1598 struct ulist_node *node;
1599 struct seq_list elem = SEQ_LIST_INIT(elem);
1600 int ret = 0;
1601
1602 tmp = ulist_alloc(GFP_NOFS);
1603 roots = ulist_alloc(GFP_NOFS);
1604 if (!tmp || !roots) {
1605 ulist_free(tmp);
1606 ulist_free(roots);
1607 return -ENOMEM;
1608 }
1609
1610 if (trans)
1611 btrfs_get_tree_mod_seq(fs_info, &elem);
1612 else
1613 down_read(&fs_info->commit_root_sem);
1614 ULIST_ITER_INIT(&uiter);
1615 while (1) {
1616 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1617 roots, NULL, root_objectid, inum, 1);
1618 if (ret == BACKREF_FOUND_SHARED) {
1619 /* this is the only condition under which we return 1 */
1620 ret = 1;
1621 break;
1622 }
1623 if (ret < 0 && ret != -ENOENT)
1624 break;
1625 ret = 0;
1626 node = ulist_next(tmp, &uiter);
1627 if (!node)
1628 break;
1629 bytenr = node->val;
1630 cond_resched();
1631 }
1632 if (trans)
1633 btrfs_put_tree_mod_seq(fs_info, &elem);
1634 else
1635 up_read(&fs_info->commit_root_sem);
1636 ulist_free(tmp);
1637 ulist_free(roots);
1638 return ret;
1639}
1640
1641int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1642 u64 start_off, struct btrfs_path *path,
1643 struct btrfs_inode_extref **ret_extref,
1644 u64 *found_off)
1645{
1646 int ret, slot;
1647 struct btrfs_key key;
1648 struct btrfs_key found_key;
1649 struct btrfs_inode_extref *extref;
1650 struct extent_buffer *leaf;
1651 unsigned long ptr;
1652
1653 key.objectid = inode_objectid;
1654 key.type = BTRFS_INODE_EXTREF_KEY;
1655 key.offset = start_off;
1656
1657 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1658 if (ret < 0)
1659 return ret;
1660
1661 while (1) {
1662 leaf = path->nodes[0];
1663 slot = path->slots[0];
1664 if (slot >= btrfs_header_nritems(leaf)) {
1665 /*
1666 * If the item at offset is not found,
1667 * btrfs_search_slot will point us to the slot
1668 * where it should be inserted. In our case
1669 * that will be the slot directly before the
1670 * next INODE_REF_KEY_V2 item. In the case
1671 * that we're pointing to the last slot in a
1672 * leaf, we must move one leaf over.
1673 */
1674 ret = btrfs_next_leaf(root, path);
1675 if (ret) {
1676 if (ret >= 1)
1677 ret = -ENOENT;
1678 break;
1679 }
1680 continue;
1681 }
1682
1683 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1684
1685 /*
1686 * Check that we're still looking at an extended ref key for
1687 * this particular objectid. If we have different
1688 * objectid or type then there are no more to be found
1689 * in the tree and we can exit.
1690 */
1691 ret = -ENOENT;
1692 if (found_key.objectid != inode_objectid)
1693 break;
1694 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1695 break;
1696
1697 ret = 0;
1698 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1699 extref = (struct btrfs_inode_extref *)ptr;
1700 *ret_extref = extref;
1701 if (found_off)
1702 *found_off = found_key.offset;
1703 break;
1704 }
1705
1706 return ret;
1707}
1708
1709/*
1710 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1711 * Elements of the path are separated by '/' and the path is guaranteed to be
1712 * 0-terminated. the path is only given within the current file system.
1713 * Therefore, it never starts with a '/'. the caller is responsible to provide
1714 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1715 * the start point of the resulting string is returned. this pointer is within
1716 * dest, normally.
1717 * in case the path buffer would overflow, the pointer is decremented further
1718 * as if output was written to the buffer, though no more output is actually
1719 * generated. that way, the caller can determine how much space would be
1720 * required for the path to fit into the buffer. in that case, the returned
1721 * value will be smaller than dest. callers must check this!
1722 */
1723char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1724 u32 name_len, unsigned long name_off,
1725 struct extent_buffer *eb_in, u64 parent,
1726 char *dest, u32 size)
1727{
1728 int slot;
1729 u64 next_inum;
1730 int ret;
1731 s64 bytes_left = ((s64)size) - 1;
1732 struct extent_buffer *eb = eb_in;
1733 struct btrfs_key found_key;
1734 int leave_spinning = path->leave_spinning;
1735 struct btrfs_inode_ref *iref;
1736
1737 if (bytes_left >= 0)
1738 dest[bytes_left] = '\0';
1739
1740 path->leave_spinning = 1;
1741 while (1) {
1742 bytes_left -= name_len;
1743 if (bytes_left >= 0)
1744 read_extent_buffer(eb, dest + bytes_left,
1745 name_off, name_len);
1746 if (eb != eb_in) {
1747 if (!path->skip_locking)
1748 btrfs_tree_read_unlock_blocking(eb);
1749 free_extent_buffer(eb);
1750 }
1751 ret = btrfs_find_item(fs_root, path, parent, 0,
1752 BTRFS_INODE_REF_KEY, &found_key);
1753 if (ret > 0)
1754 ret = -ENOENT;
1755 if (ret)
1756 break;
1757
1758 next_inum = found_key.offset;
1759
1760 /* regular exit ahead */
1761 if (parent == next_inum)
1762 break;
1763
1764 slot = path->slots[0];
1765 eb = path->nodes[0];
1766 /* make sure we can use eb after releasing the path */
1767 if (eb != eb_in) {
1768 if (!path->skip_locking)
1769 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1770 path->nodes[0] = NULL;
1771 path->locks[0] = 0;
1772 }
1773 btrfs_release_path(path);
1774 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1775
1776 name_len = btrfs_inode_ref_name_len(eb, iref);
1777 name_off = (unsigned long)(iref + 1);
1778
1779 parent = next_inum;
1780 --bytes_left;
1781 if (bytes_left >= 0)
1782 dest[bytes_left] = '/';
1783 }
1784
1785 btrfs_release_path(path);
1786 path->leave_spinning = leave_spinning;
1787
1788 if (ret)
1789 return ERR_PTR(ret);
1790
1791 return dest + bytes_left;
1792}
1793
1794/*
1795 * this makes the path point to (logical EXTENT_ITEM *)
1796 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1797 * tree blocks and <0 on error.
1798 */
1799int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1800 struct btrfs_path *path, struct btrfs_key *found_key,
1801 u64 *flags_ret)
1802{
1803 int ret;
1804 u64 flags;
1805 u64 size = 0;
1806 u32 item_size;
1807 struct extent_buffer *eb;
1808 struct btrfs_extent_item *ei;
1809 struct btrfs_key key;
1810
1811 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1812 key.type = BTRFS_METADATA_ITEM_KEY;
1813 else
1814 key.type = BTRFS_EXTENT_ITEM_KEY;
1815 key.objectid = logical;
1816 key.offset = (u64)-1;
1817
1818 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1819 if (ret < 0)
1820 return ret;
1821
1822 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1823 if (ret) {
1824 if (ret > 0)
1825 ret = -ENOENT;
1826 return ret;
1827 }
1828 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1829 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1830 size = fs_info->nodesize;
1831 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1832 size = found_key->offset;
1833
1834 if (found_key->objectid > logical ||
1835 found_key->objectid + size <= logical) {
1836 btrfs_debug(fs_info,
1837 "logical %llu is not within any extent", logical);
1838 return -ENOENT;
1839 }
1840
1841 eb = path->nodes[0];
1842 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1843 BUG_ON(item_size < sizeof(*ei));
1844
1845 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1846 flags = btrfs_extent_flags(eb, ei);
1847
1848 btrfs_debug(fs_info,
1849 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1850 logical, logical - found_key->objectid, found_key->objectid,
1851 found_key->offset, flags, item_size);
1852
1853 WARN_ON(!flags_ret);
1854 if (flags_ret) {
1855 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1856 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1857 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1858 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1859 else
1860 BUG_ON(1);
1861 return 0;
1862 }
1863
1864 return -EIO;
1865}
1866
1867/*
1868 * helper function to iterate extent inline refs. ptr must point to a 0 value
1869 * for the first call and may be modified. it is used to track state.
1870 * if more refs exist, 0 is returned and the next call to
1871 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1872 * next ref. after the last ref was processed, 1 is returned.
1873 * returns <0 on error
1874 */
1875static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1876 struct btrfs_key *key,
1877 struct btrfs_extent_item *ei, u32 item_size,
1878 struct btrfs_extent_inline_ref **out_eiref,
1879 int *out_type)
1880{
1881 unsigned long end;
1882 u64 flags;
1883 struct btrfs_tree_block_info *info;
1884
1885 if (!*ptr) {
1886 /* first call */
1887 flags = btrfs_extent_flags(eb, ei);
1888 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1889 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1890 /* a skinny metadata extent */
1891 *out_eiref =
1892 (struct btrfs_extent_inline_ref *)(ei + 1);
1893 } else {
1894 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1895 info = (struct btrfs_tree_block_info *)(ei + 1);
1896 *out_eiref =
1897 (struct btrfs_extent_inline_ref *)(info + 1);
1898 }
1899 } else {
1900 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1901 }
1902 *ptr = (unsigned long)*out_eiref;
1903 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1904 return -ENOENT;
1905 }
1906
1907 end = (unsigned long)ei + item_size;
1908 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1909 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1910
1911 *ptr += btrfs_extent_inline_ref_size(*out_type);
1912 WARN_ON(*ptr > end);
1913 if (*ptr == end)
1914 return 1; /* last */
1915
1916 return 0;
1917}
1918
1919/*
1920 * reads the tree block backref for an extent. tree level and root are returned
1921 * through out_level and out_root. ptr must point to a 0 value for the first
1922 * call and may be modified (see __get_extent_inline_ref comment).
1923 * returns 0 if data was provided, 1 if there was no more data to provide or
1924 * <0 on error.
1925 */
1926int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1927 struct btrfs_key *key, struct btrfs_extent_item *ei,
1928 u32 item_size, u64 *out_root, u8 *out_level)
1929{
1930 int ret;
1931 int type;
1932 struct btrfs_extent_inline_ref *eiref;
1933
1934 if (*ptr == (unsigned long)-1)
1935 return 1;
1936
1937 while (1) {
1938 ret = __get_extent_inline_ref(ptr, eb, key, ei, item_size,
1939 &eiref, &type);
1940 if (ret < 0)
1941 return ret;
1942
1943 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1944 type == BTRFS_SHARED_BLOCK_REF_KEY)
1945 break;
1946
1947 if (ret == 1)
1948 return 1;
1949 }
1950
1951 /* we can treat both ref types equally here */
1952 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1953
1954 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1955 struct btrfs_tree_block_info *info;
1956
1957 info = (struct btrfs_tree_block_info *)(ei + 1);
1958 *out_level = btrfs_tree_block_level(eb, info);
1959 } else {
1960 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1961 *out_level = (u8)key->offset;
1962 }
1963
1964 if (ret == 1)
1965 *ptr = (unsigned long)-1;
1966
1967 return 0;
1968}
1969
1970static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1971 struct extent_inode_elem *inode_list,
1972 u64 root, u64 extent_item_objectid,
1973 iterate_extent_inodes_t *iterate, void *ctx)
1974{
1975 struct extent_inode_elem *eie;
1976 int ret = 0;
1977
1978 for (eie = inode_list; eie; eie = eie->next) {
1979 btrfs_debug(fs_info,
1980 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1981 extent_item_objectid, eie->inum,
1982 eie->offset, root);
1983 ret = iterate(eie->inum, eie->offset, root, ctx);
1984 if (ret) {
1985 btrfs_debug(fs_info,
1986 "stopping iteration for %llu due to ret=%d",
1987 extent_item_objectid, ret);
1988 break;
1989 }
1990 }
1991
1992 return ret;
1993}
1994
1995/*
1996 * calls iterate() for every inode that references the extent identified by
1997 * the given parameters.
1998 * when the iterator function returns a non-zero value, iteration stops.
1999 */
2000int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
2001 u64 extent_item_objectid, u64 extent_item_pos,
2002 int search_commit_root,
2003 iterate_extent_inodes_t *iterate, void *ctx)
2004{
2005 int ret;
2006 struct btrfs_trans_handle *trans = NULL;
2007 struct ulist *refs = NULL;
2008 struct ulist *roots = NULL;
2009 struct ulist_node *ref_node = NULL;
2010 struct ulist_node *root_node = NULL;
2011 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
2012 struct ulist_iterator ref_uiter;
2013 struct ulist_iterator root_uiter;
2014
2015 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
2016 extent_item_objectid);
2017
2018 if (!search_commit_root) {
2019 trans = btrfs_join_transaction(fs_info->extent_root);
2020 if (IS_ERR(trans))
2021 return PTR_ERR(trans);
2022 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
2023 } else {
2024 down_read(&fs_info->commit_root_sem);
2025 }
2026
2027 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
2028 tree_mod_seq_elem.seq, &refs,
2029 &extent_item_pos);
2030 if (ret)
2031 goto out;
2032
2033 ULIST_ITER_INIT(&ref_uiter);
2034 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
2035 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
2036 tree_mod_seq_elem.seq, &roots);
2037 if (ret)
2038 break;
2039 ULIST_ITER_INIT(&root_uiter);
2040 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
2041 btrfs_debug(fs_info,
2042 "root %llu references leaf %llu, data list %#llx",
2043 root_node->val, ref_node->val,
2044 ref_node->aux);
2045 ret = iterate_leaf_refs(fs_info,
2046 (struct extent_inode_elem *)
2047 (uintptr_t)ref_node->aux,
2048 root_node->val,
2049 extent_item_objectid,
2050 iterate, ctx);
2051 }
2052 ulist_free(roots);
2053 }
2054
2055 free_leaf_list(refs);
2056out:
2057 if (!search_commit_root) {
2058 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
2059 btrfs_end_transaction(trans);
2060 } else {
2061 up_read(&fs_info->commit_root_sem);
2062 }
2063
2064 return ret;
2065}
2066
2067int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
2068 struct btrfs_path *path,
2069 iterate_extent_inodes_t *iterate, void *ctx)
2070{
2071 int ret;
2072 u64 extent_item_pos;
2073 u64 flags = 0;
2074 struct btrfs_key found_key;
2075 int search_commit_root = path->search_commit_root;
2076
2077 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
2078 btrfs_release_path(path);
2079 if (ret < 0)
2080 return ret;
2081 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2082 return -EINVAL;
2083
2084 extent_item_pos = logical - found_key.objectid;
2085 ret = iterate_extent_inodes(fs_info, found_key.objectid,
2086 extent_item_pos, search_commit_root,
2087 iterate, ctx);
2088
2089 return ret;
2090}
2091
2092typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
2093 struct extent_buffer *eb, void *ctx);
2094
2095static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
2096 struct btrfs_path *path,
2097 iterate_irefs_t *iterate, void *ctx)
2098{
2099 int ret = 0;
2100 int slot;
2101 u32 cur;
2102 u32 len;
2103 u32 name_len;
2104 u64 parent = 0;
2105 int found = 0;
2106 struct extent_buffer *eb;
2107 struct btrfs_item *item;
2108 struct btrfs_inode_ref *iref;
2109 struct btrfs_key found_key;
2110
2111 while (!ret) {
2112 ret = btrfs_find_item(fs_root, path, inum,
2113 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2114 &found_key);
2115
2116 if (ret < 0)
2117 break;
2118 if (ret) {
2119 ret = found ? 0 : -ENOENT;
2120 break;
2121 }
2122 ++found;
2123
2124 parent = found_key.offset;
2125 slot = path->slots[0];
2126 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2127 if (!eb) {
2128 ret = -ENOMEM;
2129 break;
2130 }
2131 extent_buffer_get(eb);
2132 btrfs_tree_read_lock(eb);
2133 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2134 btrfs_release_path(path);
2135
2136 item = btrfs_item_nr(slot);
2137 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2138
2139 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
2140 name_len = btrfs_inode_ref_name_len(eb, iref);
2141 /* path must be released before calling iterate()! */
2142 btrfs_debug(fs_root->fs_info,
2143 "following ref at offset %u for inode %llu in tree %llu",
2144 cur, found_key.objectid, fs_root->objectid);
2145 ret = iterate(parent, name_len,
2146 (unsigned long)(iref + 1), eb, ctx);
2147 if (ret)
2148 break;
2149 len = sizeof(*iref) + name_len;
2150 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2151 }
2152 btrfs_tree_read_unlock_blocking(eb);
2153 free_extent_buffer(eb);
2154 }
2155
2156 btrfs_release_path(path);
2157
2158 return ret;
2159}
2160
2161static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
2162 struct btrfs_path *path,
2163 iterate_irefs_t *iterate, void *ctx)
2164{
2165 int ret;
2166 int slot;
2167 u64 offset = 0;
2168 u64 parent;
2169 int found = 0;
2170 struct extent_buffer *eb;
2171 struct btrfs_inode_extref *extref;
2172 u32 item_size;
2173 u32 cur_offset;
2174 unsigned long ptr;
2175
2176 while (1) {
2177 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2178 &offset);
2179 if (ret < 0)
2180 break;
2181 if (ret) {
2182 ret = found ? 0 : -ENOENT;
2183 break;
2184 }
2185 ++found;
2186
2187 slot = path->slots[0];
2188 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2189 if (!eb) {
2190 ret = -ENOMEM;
2191 break;
2192 }
2193 extent_buffer_get(eb);
2194
2195 btrfs_tree_read_lock(eb);
2196 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2197 btrfs_release_path(path);
2198
2199 item_size = btrfs_item_size_nr(eb, slot);
2200 ptr = btrfs_item_ptr_offset(eb, slot);
2201 cur_offset = 0;
2202
2203 while (cur_offset < item_size) {
2204 u32 name_len;
2205
2206 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2207 parent = btrfs_inode_extref_parent(eb, extref);
2208 name_len = btrfs_inode_extref_name_len(eb, extref);
2209 ret = iterate(parent, name_len,
2210 (unsigned long)&extref->name, eb, ctx);
2211 if (ret)
2212 break;
2213
2214 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2215 cur_offset += sizeof(*extref);
2216 }
2217 btrfs_tree_read_unlock_blocking(eb);
2218 free_extent_buffer(eb);
2219
2220 offset++;
2221 }
2222
2223 btrfs_release_path(path);
2224
2225 return ret;
2226}
2227
2228static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
2229 struct btrfs_path *path, iterate_irefs_t *iterate,
2230 void *ctx)
2231{
2232 int ret;
2233 int found_refs = 0;
2234
2235 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
2236 if (!ret)
2237 ++found_refs;
2238 else if (ret != -ENOENT)
2239 return ret;
2240
2241 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
2242 if (ret == -ENOENT && found_refs)
2243 return 0;
2244
2245 return ret;
2246}
2247
2248/*
2249 * returns 0 if the path could be dumped (probably truncated)
2250 * returns <0 in case of an error
2251 */
2252static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2253 struct extent_buffer *eb, void *ctx)
2254{
2255 struct inode_fs_paths *ipath = ctx;
2256 char *fspath;
2257 char *fspath_min;
2258 int i = ipath->fspath->elem_cnt;
2259 const int s_ptr = sizeof(char *);
2260 u32 bytes_left;
2261
2262 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2263 ipath->fspath->bytes_left - s_ptr : 0;
2264
2265 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2266 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2267 name_off, eb, inum, fspath_min, bytes_left);
2268 if (IS_ERR(fspath))
2269 return PTR_ERR(fspath);
2270
2271 if (fspath > fspath_min) {
2272 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2273 ++ipath->fspath->elem_cnt;
2274 ipath->fspath->bytes_left = fspath - fspath_min;
2275 } else {
2276 ++ipath->fspath->elem_missed;
2277 ipath->fspath->bytes_missing += fspath_min - fspath;
2278 ipath->fspath->bytes_left = 0;
2279 }
2280
2281 return 0;
2282}
2283
2284/*
2285 * this dumps all file system paths to the inode into the ipath struct, provided
2286 * is has been created large enough. each path is zero-terminated and accessed
2287 * from ipath->fspath->val[i].
2288 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2289 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2290 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2291 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2292 * have been needed to return all paths.
2293 */
2294int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2295{
2296 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
2297 inode_to_path, ipath);
2298}
2299
2300struct btrfs_data_container *init_data_container(u32 total_bytes)
2301{
2302 struct btrfs_data_container *data;
2303 size_t alloc_bytes;
2304
2305 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2306 data = vmalloc(alloc_bytes);
2307 if (!data)
2308 return ERR_PTR(-ENOMEM);
2309
2310 if (total_bytes >= sizeof(*data)) {
2311 data->bytes_left = total_bytes - sizeof(*data);
2312 data->bytes_missing = 0;
2313 } else {
2314 data->bytes_missing = sizeof(*data) - total_bytes;
2315 data->bytes_left = 0;
2316 }
2317
2318 data->elem_cnt = 0;
2319 data->elem_missed = 0;
2320
2321 return data;
2322}
2323
2324/*
2325 * allocates space to return multiple file system paths for an inode.
2326 * total_bytes to allocate are passed, note that space usable for actual path
2327 * information will be total_bytes - sizeof(struct inode_fs_paths).
2328 * the returned pointer must be freed with free_ipath() in the end.
2329 */
2330struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2331 struct btrfs_path *path)
2332{
2333 struct inode_fs_paths *ifp;
2334 struct btrfs_data_container *fspath;
2335
2336 fspath = init_data_container(total_bytes);
2337 if (IS_ERR(fspath))
2338 return (void *)fspath;
2339
2340 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
2341 if (!ifp) {
2342 vfree(fspath);
2343 return ERR_PTR(-ENOMEM);
2344 }
2345
2346 ifp->btrfs_path = path;
2347 ifp->fspath = fspath;
2348 ifp->fs_root = fs_root;
2349
2350 return ifp;
2351}
2352
2353void free_ipath(struct inode_fs_paths *ipath)
2354{
2355 if (!ipath)
2356 return;
2357 vfree(ipath->fspath);
2358 kfree(ipath);
2359}