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net/netfilter/nf_conntrack_core: Fix net_conntrack_lock()
[linux/fpc-iii.git] / fs / btrfs / backref.c
blobf723c11bb763b1ebd028d08d5a45151f6d897c8c
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/mm.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 enum merge_mode {
30 MERGE_IDENTICAL_KEYS = 1,
31 MERGE_IDENTICAL_PARENTS,
32 };
33
34 /* Just an arbitrary number so we can be sure this happened */
35 #define BACKREF_FOUND_SHARED 6
36
37 struct extent_inode_elem {
38 u64 inum;
39 u64 offset;
40 struct extent_inode_elem *next;
41 };
42
43 /*
44 * ref_root is used as the root of the ref tree that hold a collection
45 * of unique references.
46 */
47 struct ref_root {
48 struct rb_root rb_root;
49
50 /*
51 * The unique_refs represents the number of ref_nodes with a positive
52 * count stored in the tree. Even if a ref_node (the count is greater
53 * than one) is added, the unique_refs will only increase by one.
54 */
55 unsigned int unique_refs;
56 };
57
58 /* ref_node is used to store a unique reference to the ref tree. */
59 struct ref_node {
60 struct rb_node rb_node;
61
62 /* For NORMAL_REF, otherwise all these fields should be set to 0 */
63 u64 root_id;
64 u64 object_id;
65 u64 offset;
66
67 /* For SHARED_REF, otherwise parent field should be set to 0 */
68 u64 parent;
69
70 /* Ref to the ref_mod of btrfs_delayed_ref_node */
71 int ref_mod;
72 };
73
74 /* Dynamically allocate and initialize a ref_root */
75 static struct ref_root *ref_root_alloc(void)
76 {
77 struct ref_root *ref_tree;
78
79 ref_tree = kmalloc(sizeof(*ref_tree), GFP_NOFS);
80 if (!ref_tree)
81 return NULL;
82
83 ref_tree->rb_root = RB_ROOT;
84 ref_tree->unique_refs = 0;
85
86 return ref_tree;
87 }
88
89 /* Free all nodes in the ref tree, and reinit ref_root */
90 static void ref_root_fini(struct ref_root *ref_tree)
91 {
92 struct ref_node *node;
93 struct rb_node *next;
94
95 while ((next = rb_first(&ref_tree->rb_root)) != NULL) {
96 node = rb_entry(next, struct ref_node, rb_node);
97 rb_erase(next, &ref_tree->rb_root);
98 kfree(node);
99 }
100
101 ref_tree->rb_root = RB_ROOT;
102 ref_tree->unique_refs = 0;
103 }
104
105 static void ref_root_free(struct ref_root *ref_tree)
106 {
107 if (!ref_tree)
108 return;
109
110 ref_root_fini(ref_tree);
111 kfree(ref_tree);
112 }
113
114 /*
115 * Compare ref_node with (root_id, object_id, offset, parent)
116 *
117 * The function compares two ref_node a and b. It returns an integer less
118 * than, equal to, or greater than zero , respectively, to be less than, to
119 * equal, or be greater than b.
120 */
121 static int ref_node_cmp(struct ref_node *a, struct ref_node *b)
122 {
123 if (a->root_id < b->root_id)
124 return -1;
125 else if (a->root_id > b->root_id)
126 return 1;
127
128 if (a->object_id < b->object_id)
129 return -1;
130 else if (a->object_id > b->object_id)
131 return 1;
132
133 if (a->offset < b->offset)
134 return -1;
135 else if (a->offset > b->offset)
136 return 1;
137
138 if (a->parent < b->parent)
139 return -1;
140 else if (a->parent > b->parent)
141 return 1;
142
143 return 0;
144 }
145
146 /*
147 * Search ref_node with (root_id, object_id, offset, parent) in the tree
148 *
149 * if found, the pointer of the ref_node will be returned;
150 * if not found, NULL will be returned and pos will point to the rb_node for
151 * insert, pos_parent will point to pos'parent for insert;
152 */
153 static struct ref_node *__ref_tree_search(struct ref_root *ref_tree,
154 struct rb_node ***pos,
155 struct rb_node **pos_parent,
156 u64 root_id, u64 object_id,
157 u64 offset, u64 parent)
158 {
159 struct ref_node *cur = NULL;
160 struct ref_node entry;
161 int ret;
162
163 entry.root_id = root_id;
164 entry.object_id = object_id;
165 entry.offset = offset;
166 entry.parent = parent;
167
168 *pos = &ref_tree->rb_root.rb_node;
169
170 while (**pos) {
171 *pos_parent = **pos;
172 cur = rb_entry(*pos_parent, struct ref_node, rb_node);
173
174 ret = ref_node_cmp(cur, &entry);
175 if (ret > 0)
176 *pos = &(**pos)->rb_left;
177 else if (ret < 0)
178 *pos = &(**pos)->rb_right;
179 else
180 return cur;
181 }
182
183 return NULL;
184 }
185
186 /*
187 * Insert a ref_node to the ref tree
188 * @pos used for specifiy the position to insert
189 * @pos_parent for specifiy pos's parent
190 *
191 * success, return 0;
192 * ref_node already exists, return -EEXIST;
193 */
194 static int ref_tree_insert(struct ref_root *ref_tree, struct rb_node **pos,
195 struct rb_node *pos_parent, struct ref_node *ins)
196 {
197 struct rb_node **p = NULL;
198 struct rb_node *parent = NULL;
199 struct ref_node *cur = NULL;
200
201 if (!pos) {
202 cur = __ref_tree_search(ref_tree, &p, &parent, ins->root_id,
203 ins->object_id, ins->offset,
204 ins->parent);
205 if (cur)
206 return -EEXIST;
207 } else {
208 p = pos;
209 parent = pos_parent;
210 }
211
212 rb_link_node(&ins->rb_node, parent, p);
213 rb_insert_color(&ins->rb_node, &ref_tree->rb_root);
214
215 return 0;
216 }
217
218 /* Erase and free ref_node, caller should update ref_root->unique_refs */
219 static void ref_tree_remove(struct ref_root *ref_tree, struct ref_node *node)
220 {
221 rb_erase(&node->rb_node, &ref_tree->rb_root);
222 kfree(node);
223 }
224
225 /*
226 * Update ref_root->unique_refs
227 *
228 * Call __ref_tree_search
229 * 1. if ref_node doesn't exist, ref_tree_insert this node, and update
230 * ref_root->unique_refs:
231 * if ref_node->ref_mod > 0, ref_root->unique_refs++;
232 * if ref_node->ref_mod < 0, do noting;
233 *
234 * 2. if ref_node is found, then get origin ref_node->ref_mod, and update
235 * ref_node->ref_mod.
236 * if ref_node->ref_mod is equal to 0,then call ref_tree_remove
237 *
238 * according to origin_mod and new_mod, update ref_root->items
239 * +----------------+--------------+-------------+
240 * | |new_count <= 0|new_count > 0|
241 * +----------------+--------------+-------------+
242 * |origin_count < 0| 0 | 1 |
243 * +----------------+--------------+-------------+
244 * |origin_count > 0| -1 | 0 |
245 * +----------------+--------------+-------------+
246 *
247 * In case of allocation failure, -ENOMEM is returned and the ref_tree stays
248 * unaltered.
249 * Success, return 0
250 */
251 static int ref_tree_add(struct ref_root *ref_tree, u64 root_id, u64 object_id,
252 u64 offset, u64 parent, int count)
253 {
254 struct ref_node *node = NULL;
255 struct rb_node **pos = NULL;
256 struct rb_node *pos_parent = NULL;
257 int origin_count;
258 int ret;
259
260 if (!count)
261 return 0;
262
263 node = __ref_tree_search(ref_tree, &pos, &pos_parent, root_id,
264 object_id, offset, parent);
265 if (node == NULL) {
266 node = kmalloc(sizeof(*node), GFP_NOFS);
267 if (!node)
268 return -ENOMEM;
269
270 node->root_id = root_id;
271 node->object_id = object_id;
272 node->offset = offset;
273 node->parent = parent;
274 node->ref_mod = count;
275
276 ret = ref_tree_insert(ref_tree, pos, pos_parent, node);
277 ASSERT(!ret);
278 if (ret) {
279 kfree(node);
280 return ret;
281 }
282
283 ref_tree->unique_refs += node->ref_mod > 0 ? 1 : 0;
284
285 return 0;
286 }
287
288 origin_count = node->ref_mod;
289 node->ref_mod += count;
290
291 if (node->ref_mod > 0)
292 ref_tree->unique_refs += origin_count > 0 ? 0 : 1;
293 else if (node->ref_mod <= 0)
294 ref_tree->unique_refs += origin_count > 0 ? -1 : 0;
295
296 if (!node->ref_mod)
297 ref_tree_remove(ref_tree, node);
298
299 return 0;
300 }
301
302 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
303 struct btrfs_file_extent_item *fi,
304 u64 extent_item_pos,
305 struct extent_inode_elem **eie)
306 {
307 u64 offset = 0;
308 struct extent_inode_elem *e;
309
310 if (!btrfs_file_extent_compression(eb, fi) &&
311 !btrfs_file_extent_encryption(eb, fi) &&
312 !btrfs_file_extent_other_encoding(eb, fi)) {
313 u64 data_offset;
314 u64 data_len;
315
316 data_offset = btrfs_file_extent_offset(eb, fi);
317 data_len = btrfs_file_extent_num_bytes(eb, fi);
318
319 if (extent_item_pos < data_offset ||
320 extent_item_pos >= data_offset + data_len)
321 return 1;
322 offset = extent_item_pos - data_offset;
323 }
324
325 e = kmalloc(sizeof(*e), GFP_NOFS);
326 if (!e)
327 return -ENOMEM;
328
329 e->next = *eie;
330 e->inum = key->objectid;
331 e->offset = key->offset + offset;
332 *eie = e;
333
334 return 0;
335 }
336
337 static void free_inode_elem_list(struct extent_inode_elem *eie)
338 {
339 struct extent_inode_elem *eie_next;
340
341 for (; eie; eie = eie_next) {
342 eie_next = eie->next;
343 kfree(eie);
344 }
345 }
346
347 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
348 u64 extent_item_pos,
349 struct extent_inode_elem **eie)
350 {
351 u64 disk_byte;
352 struct btrfs_key key;
353 struct btrfs_file_extent_item *fi;
354 int slot;
355 int nritems;
356 int extent_type;
357 int ret;
358
359 /*
360 * from the shared data ref, we only have the leaf but we need
361 * the key. thus, we must look into all items and see that we
362 * find one (some) with a reference to our extent item.
363 */
364 nritems = btrfs_header_nritems(eb);
365 for (slot = 0; slot < nritems; ++slot) {
366 btrfs_item_key_to_cpu(eb, &key, slot);
367 if (key.type != BTRFS_EXTENT_DATA_KEY)
368 continue;
369 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
370 extent_type = btrfs_file_extent_type(eb, fi);
371 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
372 continue;
373 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
374 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
375 if (disk_byte != wanted_disk_byte)
376 continue;
377
378 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
379 if (ret < 0)
380 return ret;
381 }
382
383 return 0;
384 }
385
386 /*
387 * this structure records all encountered refs on the way up to the root
388 */
389 struct __prelim_ref {
390 struct list_head list;
391 u64 root_id;
392 struct btrfs_key key_for_search;
393 int level;
394 int count;
395 struct extent_inode_elem *inode_list;
396 u64 parent;
397 u64 wanted_disk_byte;
398 };
399
400 static struct kmem_cache *btrfs_prelim_ref_cache;
401
402 int __init btrfs_prelim_ref_init(void)
403 {
404 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
405 sizeof(struct __prelim_ref),
406 0,
407 SLAB_MEM_SPREAD,
408 NULL);
409 if (!btrfs_prelim_ref_cache)
410 return -ENOMEM;
411 return 0;
412 }
413
414 void btrfs_prelim_ref_exit(void)
415 {
416 kmem_cache_destroy(btrfs_prelim_ref_cache);
417 }
418
419 /*
420 * the rules for all callers of this function are:
421 * - obtaining the parent is the goal
422 * - if you add a key, you must know that it is a correct key
423 * - if you cannot add the parent or a correct key, then we will look into the
424 * block later to set a correct key
425 *
426 * delayed refs
427 * ============
428 * backref type | shared | indirect | shared | indirect
429 * information | tree | tree | data | data
430 * --------------------+--------+----------+--------+----------
431 * parent logical | y | - | - | -
432 * key to resolve | - | y | y | y
433 * tree block logical | - | - | - | -
434 * root for resolving | y | y | y | y
435 *
436 * - column 1: we've the parent -> done
437 * - column 2, 3, 4: we use the key to find the parent
438 *
439 * on disk refs (inline or keyed)
440 * ==============================
441 * backref type | shared | indirect | shared | indirect
442 * information | tree | tree | data | data
443 * --------------------+--------+----------+--------+----------
444 * parent logical | y | - | y | -
445 * key to resolve | - | - | - | y
446 * tree block logical | y | y | y | y
447 * root for resolving | - | y | y | y
448 *
449 * - column 1, 3: we've the parent -> done
450 * - column 2: we take the first key from the block to find the parent
451 * (see __add_missing_keys)
452 * - column 4: we use the key to find the parent
453 *
454 * additional information that's available but not required to find the parent
455 * block might help in merging entries to gain some speed.
456 */
457
458 static int __add_prelim_ref(struct list_head *head, u64 root_id,
459 struct btrfs_key *key, int level,
460 u64 parent, u64 wanted_disk_byte, int count,
461 gfp_t gfp_mask)
462 {
463 struct __prelim_ref *ref;
464
465 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
466 return 0;
467
468 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
469 if (!ref)
470 return -ENOMEM;
471
472 ref->root_id = root_id;
473 if (key) {
474 ref->key_for_search = *key;
475 /*
476 * We can often find data backrefs with an offset that is too
477 * large (>= LLONG_MAX, maximum allowed file offset) due to
478 * underflows when subtracting a file's offset with the data
479 * offset of its corresponding extent data item. This can
480 * happen for example in the clone ioctl.
481 * So if we detect such case we set the search key's offset to
482 * zero to make sure we will find the matching file extent item
483 * at add_all_parents(), otherwise we will miss it because the
484 * offset taken form the backref is much larger then the offset
485 * of the file extent item. This can make us scan a very large
486 * number of file extent items, but at least it will not make
487 * us miss any.
488 * This is an ugly workaround for a behaviour that should have
489 * never existed, but it does and a fix for the clone ioctl
490 * would touch a lot of places, cause backwards incompatibility
491 * and would not fix the problem for extents cloned with older
492 * kernels.
493 */
494 if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY &&
495 ref->key_for_search.offset >= LLONG_MAX)
496 ref->key_for_search.offset = 0;
497 } else {
498 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
499 }
500
501 ref->inode_list = NULL;
502 ref->level = level;
503 ref->count = count;
504 ref->parent = parent;
505 ref->wanted_disk_byte = wanted_disk_byte;
506 list_add_tail(&ref->list, head);
507
508 return 0;
509 }
510
511 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
512 struct ulist *parents, struct __prelim_ref *ref,
513 int level, u64 time_seq, const u64 *extent_item_pos,
514 u64 total_refs)
515 {
516 int ret = 0;
517 int slot;
518 struct extent_buffer *eb;
519 struct btrfs_key key;
520 struct btrfs_key *key_for_search = &ref->key_for_search;
521 struct btrfs_file_extent_item *fi;
522 struct extent_inode_elem *eie = NULL, *old = NULL;
523 u64 disk_byte;
524 u64 wanted_disk_byte = ref->wanted_disk_byte;
525 u64 count = 0;
526
527 if (level != 0) {
528 eb = path->nodes[level];
529 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
530 if (ret < 0)
531 return ret;
532 return 0;
533 }
534
535 /*
536 * We normally enter this function with the path already pointing to
537 * the first item to check. But sometimes, we may enter it with
538 * slot==nritems. In that case, go to the next leaf before we continue.
539 */
540 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
541 if (time_seq == SEQ_LAST)
542 ret = btrfs_next_leaf(root, path);
543 else
544 ret = btrfs_next_old_leaf(root, path, time_seq);
545 }
546
547 while (!ret && count < total_refs) {
548 eb = path->nodes[0];
549 slot = path->slots[0];
550
551 btrfs_item_key_to_cpu(eb, &key, slot);
552
553 if (key.objectid != key_for_search->objectid ||
554 key.type != BTRFS_EXTENT_DATA_KEY)
555 break;
556
557 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
558 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
559
560 if (disk_byte == wanted_disk_byte) {
561 eie = NULL;
562 old = NULL;
563 count++;
564 if (extent_item_pos) {
565 ret = check_extent_in_eb(&key, eb, fi,
566 *extent_item_pos,
567 &eie);
568 if (ret < 0)
569 break;
570 }
571 if (ret > 0)
572 goto next;
573 ret = ulist_add_merge_ptr(parents, eb->start,
574 eie, (void **)&old, GFP_NOFS);
575 if (ret < 0)
576 break;
577 if (!ret && extent_item_pos) {
578 while (old->next)
579 old = old->next;
580 old->next = eie;
581 }
582 eie = NULL;
583 }
584 next:
585 if (time_seq == SEQ_LAST)
586 ret = btrfs_next_item(root, path);
587 else
588 ret = btrfs_next_old_item(root, path, time_seq);
589 }
590
591 if (ret > 0)
592 ret = 0;
593 else if (ret < 0)
594 free_inode_elem_list(eie);
595 return ret;
596 }
597
598 /*
599 * resolve an indirect backref in the form (root_id, key, level)
600 * to a logical address
601 */
602 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
603 struct btrfs_path *path, u64 time_seq,
604 struct __prelim_ref *ref,
605 struct ulist *parents,
606 const u64 *extent_item_pos, u64 total_refs)
607 {
608 struct btrfs_root *root;
609 struct btrfs_key root_key;
610 struct extent_buffer *eb;
611 int ret = 0;
612 int root_level;
613 int level = ref->level;
614 int index;
615
616 root_key.objectid = ref->root_id;
617 root_key.type = BTRFS_ROOT_ITEM_KEY;
618 root_key.offset = (u64)-1;
619
620 index = srcu_read_lock(&fs_info->subvol_srcu);
621
622 root = btrfs_get_fs_root(fs_info, &root_key, false);
623 if (IS_ERR(root)) {
624 srcu_read_unlock(&fs_info->subvol_srcu, index);
625 ret = PTR_ERR(root);
626 goto out;
627 }
628
629 if (btrfs_is_testing(fs_info)) {
630 srcu_read_unlock(&fs_info->subvol_srcu, index);
631 ret = -ENOENT;
632 goto out;
633 }
634
635 if (path->search_commit_root)
636 root_level = btrfs_header_level(root->commit_root);
637 else if (time_seq == SEQ_LAST)
638 root_level = btrfs_header_level(root->node);
639 else
640 root_level = btrfs_old_root_level(root, time_seq);
641
642 if (root_level + 1 == level) {
643 srcu_read_unlock(&fs_info->subvol_srcu, index);
644 goto out;
645 }
646
647 path->lowest_level = level;
648 if (time_seq == SEQ_LAST)
649 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path,
650 0, 0);
651 else
652 ret = btrfs_search_old_slot(root, &ref->key_for_search, path,
653 time_seq);
654
655 /* root node has been locked, we can release @subvol_srcu safely here */
656 srcu_read_unlock(&fs_info->subvol_srcu, index);
657
658 btrfs_debug(fs_info,
659 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
660 ref->root_id, level, ref->count, ret,
661 ref->key_for_search.objectid, ref->key_for_search.type,
662 ref->key_for_search.offset);
663 if (ret < 0)
664 goto out;
665
666 eb = path->nodes[level];
667 while (!eb) {
668 if (WARN_ON(!level)) {
669 ret = 1;
670 goto out;
671 }
672 level--;
673 eb = path->nodes[level];
674 }
675
676 ret = add_all_parents(root, path, parents, ref, level, time_seq,
677 extent_item_pos, total_refs);
678 out:
679 path->lowest_level = 0;
680 btrfs_release_path(path);
681 return ret;
682 }
683
684 /*
685 * resolve all indirect backrefs from the list
686 */
687 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
688 struct btrfs_path *path, u64 time_seq,
689 struct list_head *head,
690 const u64 *extent_item_pos, u64 total_refs,
691 u64 root_objectid)
692 {
693 int err;
694 int ret = 0;
695 struct __prelim_ref *ref;
696 struct __prelim_ref *ref_safe;
697 struct __prelim_ref *new_ref;
698 struct ulist *parents;
699 struct ulist_node *node;
700 struct ulist_iterator uiter;
701
702 parents = ulist_alloc(GFP_NOFS);
703 if (!parents)
704 return -ENOMEM;
705
706 /*
707 * _safe allows us to insert directly after the current item without
708 * iterating over the newly inserted items.
709 * we're also allowed to re-assign ref during iteration.
710 */
711 list_for_each_entry_safe(ref, ref_safe, head, list) {
712 if (ref->parent) /* already direct */
713 continue;
714 if (ref->count == 0)
715 continue;
716 if (root_objectid && ref->root_id != root_objectid) {
717 ret = BACKREF_FOUND_SHARED;
718 goto out;
719 }
720 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
721 parents, extent_item_pos,
722 total_refs);
723 /*
724 * we can only tolerate ENOENT,otherwise,we should catch error
725 * and return directly.
726 */
727 if (err == -ENOENT) {
728 continue;
729 } else if (err) {
730 ret = err;
731 goto out;
732 }
733
734 /* we put the first parent into the ref at hand */
735 ULIST_ITER_INIT(&uiter);
736 node = ulist_next(parents, &uiter);
737 ref->parent = node ? node->val : 0;
738 ref->inode_list = node ?
739 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
740
741 /* additional parents require new refs being added here */
742 while ((node = ulist_next(parents, &uiter))) {
743 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
744 GFP_NOFS);
745 if (!new_ref) {
746 ret = -ENOMEM;
747 goto out;
748 }
749 memcpy(new_ref, ref, sizeof(*ref));
750 new_ref->parent = node->val;
751 new_ref->inode_list = (struct extent_inode_elem *)
752 (uintptr_t)node->aux;
753 list_add(&new_ref->list, &ref->list);
754 }
755 ulist_reinit(parents);
756 }
757 out:
758 ulist_free(parents);
759 return ret;
760 }
761
762 static inline int ref_for_same_block(struct __prelim_ref *ref1,
763 struct __prelim_ref *ref2)
764 {
765 if (ref1->level != ref2->level)
766 return 0;
767 if (ref1->root_id != ref2->root_id)
768 return 0;
769 if (ref1->key_for_search.type != ref2->key_for_search.type)
770 return 0;
771 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
772 return 0;
773 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
774 return 0;
775 if (ref1->parent != ref2->parent)
776 return 0;
777
778 return 1;
779 }
780
781 /*
782 * read tree blocks and add keys where required.
783 */
784 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
785 struct list_head *head)
786 {
787 struct __prelim_ref *ref;
788 struct extent_buffer *eb;
789
790 list_for_each_entry(ref, head, list) {
791 if (ref->parent)
792 continue;
793 if (ref->key_for_search.type)
794 continue;
795 BUG_ON(!ref->wanted_disk_byte);
796 eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0);
797 if (IS_ERR(eb)) {
798 return PTR_ERR(eb);
799 } else if (!extent_buffer_uptodate(eb)) {
800 free_extent_buffer(eb);
801 return -EIO;
802 }
803 btrfs_tree_read_lock(eb);
804 if (btrfs_header_level(eb) == 0)
805 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
806 else
807 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
808 btrfs_tree_read_unlock(eb);
809 free_extent_buffer(eb);
810 }
811 return 0;
812 }
813
814 /*
815 * merge backrefs and adjust counts accordingly
816 *
817 * FIXME: For MERGE_IDENTICAL_KEYS, if we add more keys in __add_prelim_ref
818 * then we can merge more here. Additionally, we could even add a key
819 * range for the blocks we looked into to merge even more (-> replace
820 * unresolved refs by those having a parent).
821 */
822 static void __merge_refs(struct list_head *head, enum merge_mode mode)
823 {
824 struct __prelim_ref *pos1;
825
826 list_for_each_entry(pos1, head, list) {
827 struct __prelim_ref *pos2 = pos1, *tmp;
828
829 list_for_each_entry_safe_continue(pos2, tmp, head, list) {
830 struct __prelim_ref *ref1 = pos1, *ref2 = pos2;
831 struct extent_inode_elem *eie;
832
833 if (!ref_for_same_block(ref1, ref2))
834 continue;
835 if (mode == MERGE_IDENTICAL_KEYS) {
836 if (!ref1->parent && ref2->parent)
837 swap(ref1, ref2);
838 } else {
839 if (ref1->parent != ref2->parent)
840 continue;
841 }
842
843 eie = ref1->inode_list;
844 while (eie && eie->next)
845 eie = eie->next;
846 if (eie)
847 eie->next = ref2->inode_list;
848 else
849 ref1->inode_list = ref2->inode_list;
850 ref1->count += ref2->count;
851
852 list_del(&ref2->list);
853 kmem_cache_free(btrfs_prelim_ref_cache, ref2);
854 cond_resched();
855 }
856
857 }
858 }
859
860 /*
861 * add all currently queued delayed refs from this head whose seq nr is
862 * smaller or equal that seq to the list
863 */
864 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
865 struct list_head *prefs, u64 *total_refs,
866 u64 inum)
867 {
868 struct btrfs_delayed_ref_node *node;
869 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
870 struct btrfs_key key;
871 struct btrfs_key op_key = {0};
872 int sgn;
873 int ret = 0;
874
875 if (extent_op && extent_op->update_key)
876 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
877
878 spin_lock(&head->lock);
879 list_for_each_entry(node, &head->ref_list, list) {
880 if (node->seq > seq)
881 continue;
882
883 switch (node->action) {
884 case BTRFS_ADD_DELAYED_EXTENT:
885 case BTRFS_UPDATE_DELAYED_HEAD:
886 WARN_ON(1);
887 continue;
888 case BTRFS_ADD_DELAYED_REF:
889 sgn = 1;
890 break;
891 case BTRFS_DROP_DELAYED_REF:
892 sgn = -1;
893 break;
894 default:
895 BUG_ON(1);
896 }
897 *total_refs += (node->ref_mod * sgn);
898 switch (node->type) {
899 case BTRFS_TREE_BLOCK_REF_KEY: {
900 struct btrfs_delayed_tree_ref *ref;
901
902 ref = btrfs_delayed_node_to_tree_ref(node);
903 ret = __add_prelim_ref(prefs, ref->root, &op_key,
904 ref->level + 1, 0, node->bytenr,
905 node->ref_mod * sgn, GFP_ATOMIC);
906 break;
907 }
908 case BTRFS_SHARED_BLOCK_REF_KEY: {
909 struct btrfs_delayed_tree_ref *ref;
910
911 ref = btrfs_delayed_node_to_tree_ref(node);
912 ret = __add_prelim_ref(prefs, 0, NULL,
913 ref->level + 1, ref->parent,
914 node->bytenr,
915 node->ref_mod * sgn, GFP_ATOMIC);
916 break;
917 }
918 case BTRFS_EXTENT_DATA_REF_KEY: {
919 struct btrfs_delayed_data_ref *ref;
920 ref = btrfs_delayed_node_to_data_ref(node);
921
922 key.objectid = ref->objectid;
923 key.type = BTRFS_EXTENT_DATA_KEY;
924 key.offset = ref->offset;
925
926 /*
927 * Found a inum that doesn't match our known inum, we
928 * know it's shared.
929 */
930 if (inum && ref->objectid != inum) {
931 ret = BACKREF_FOUND_SHARED;
932 break;
933 }
934
935 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
936 node->bytenr,
937 node->ref_mod * sgn, GFP_ATOMIC);
938 break;
939 }
940 case BTRFS_SHARED_DATA_REF_KEY: {
941 struct btrfs_delayed_data_ref *ref;
942
943 ref = btrfs_delayed_node_to_data_ref(node);
944 ret = __add_prelim_ref(prefs, 0, NULL, 0,
945 ref->parent, node->bytenr,
946 node->ref_mod * sgn, GFP_ATOMIC);
947 break;
948 }
949 default:
950 WARN_ON(1);
951 }
952 if (ret)
953 break;
954 }
955 spin_unlock(&head->lock);
956 return ret;
957 }
958
959 /*
960 * add all inline backrefs for bytenr to the list
961 */
962 static int __add_inline_refs(struct btrfs_path *path, u64 bytenr,
963 int *info_level, struct list_head *prefs,
964 struct ref_root *ref_tree,
965 u64 *total_refs, u64 inum)
966 {
967 int ret = 0;
968 int slot;
969 struct extent_buffer *leaf;
970 struct btrfs_key key;
971 struct btrfs_key found_key;
972 unsigned long ptr;
973 unsigned long end;
974 struct btrfs_extent_item *ei;
975 u64 flags;
976 u64 item_size;
977
978 /*
979 * enumerate all inline refs
980 */
981 leaf = path->nodes[0];
982 slot = path->slots[0];
983
984 item_size = btrfs_item_size_nr(leaf, slot);
985 BUG_ON(item_size < sizeof(*ei));
986
987 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
988 flags = btrfs_extent_flags(leaf, ei);
989 *total_refs += btrfs_extent_refs(leaf, ei);
990 btrfs_item_key_to_cpu(leaf, &found_key, slot);
991
992 ptr = (unsigned long)(ei + 1);
993 end = (unsigned long)ei + item_size;
994
995 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
996 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
997 struct btrfs_tree_block_info *info;
998
999 info = (struct btrfs_tree_block_info *)ptr;
1000 *info_level = btrfs_tree_block_level(leaf, info);
1001 ptr += sizeof(struct btrfs_tree_block_info);
1002 BUG_ON(ptr > end);
1003 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
1004 *info_level = found_key.offset;
1005 } else {
1006 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
1007 }
1008
1009 while (ptr < end) {
1010 struct btrfs_extent_inline_ref *iref;
1011 u64 offset;
1012 int type;
1013
1014 iref = (struct btrfs_extent_inline_ref *)ptr;
1015 type = btrfs_extent_inline_ref_type(leaf, iref);
1016 offset = btrfs_extent_inline_ref_offset(leaf, iref);
1017
1018 switch (type) {
1019 case BTRFS_SHARED_BLOCK_REF_KEY:
1020 ret = __add_prelim_ref(prefs, 0, NULL,
1021 *info_level + 1, offset,
1022 bytenr, 1, GFP_NOFS);
1023 break;
1024 case BTRFS_SHARED_DATA_REF_KEY: {
1025 struct btrfs_shared_data_ref *sdref;
1026 int count;
1027
1028 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
1029 count = btrfs_shared_data_ref_count(leaf, sdref);
1030 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
1031 bytenr, count, GFP_NOFS);
1032 if (ref_tree) {
1033 if (!ret)
1034 ret = ref_tree_add(ref_tree, 0, 0, 0,
1035 bytenr, count);
1036 if (!ret && ref_tree->unique_refs > 1)
1037 ret = BACKREF_FOUND_SHARED;
1038 }
1039 break;
1040 }
1041 case BTRFS_TREE_BLOCK_REF_KEY:
1042 ret = __add_prelim_ref(prefs, offset, NULL,
1043 *info_level + 1, 0,
1044 bytenr, 1, GFP_NOFS);
1045 break;
1046 case BTRFS_EXTENT_DATA_REF_KEY: {
1047 struct btrfs_extent_data_ref *dref;
1048 int count;
1049 u64 root;
1050
1051 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1052 count = btrfs_extent_data_ref_count(leaf, dref);
1053 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1054 dref);
1055 key.type = BTRFS_EXTENT_DATA_KEY;
1056 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1057
1058 if (inum && key.objectid != inum) {
1059 ret = BACKREF_FOUND_SHARED;
1060 break;
1061 }
1062
1063 root = btrfs_extent_data_ref_root(leaf, dref);
1064 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
1065 bytenr, count, GFP_NOFS);
1066 if (ref_tree) {
1067 if (!ret)
1068 ret = ref_tree_add(ref_tree, root,
1069 key.objectid,
1070 key.offset, 0,
1071 count);
1072 if (!ret && ref_tree->unique_refs > 1)
1073 ret = BACKREF_FOUND_SHARED;
1074 }
1075 break;
1076 }
1077 default:
1078 WARN_ON(1);
1079 }
1080 if (ret)
1081 return ret;
1082 ptr += btrfs_extent_inline_ref_size(type);
1083 }
1084
1085 return 0;
1086 }
1087
1088 /*
1089 * add all non-inline backrefs for bytenr to the list
1090 */
1091 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
1092 struct btrfs_path *path, u64 bytenr,
1093 int info_level, struct list_head *prefs,
1094 struct ref_root *ref_tree, u64 inum)
1095 {
1096 struct btrfs_root *extent_root = fs_info->extent_root;
1097 int ret;
1098 int slot;
1099 struct extent_buffer *leaf;
1100 struct btrfs_key key;
1101
1102 while (1) {
1103 ret = btrfs_next_item(extent_root, path);
1104 if (ret < 0)
1105 break;
1106 if (ret) {
1107 ret = 0;
1108 break;
1109 }
1110
1111 slot = path->slots[0];
1112 leaf = path->nodes[0];
1113 btrfs_item_key_to_cpu(leaf, &key, slot);
1114
1115 if (key.objectid != bytenr)
1116 break;
1117 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1118 continue;
1119 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1120 break;
1121
1122 switch (key.type) {
1123 case BTRFS_SHARED_BLOCK_REF_KEY:
1124 ret = __add_prelim_ref(prefs, 0, NULL,
1125 info_level + 1, key.offset,
1126 bytenr, 1, GFP_NOFS);
1127 break;
1128 case BTRFS_SHARED_DATA_REF_KEY: {
1129 struct btrfs_shared_data_ref *sdref;
1130 int count;
1131
1132 sdref = btrfs_item_ptr(leaf, slot,
1133 struct btrfs_shared_data_ref);
1134 count = btrfs_shared_data_ref_count(leaf, sdref);
1135 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
1136 bytenr, count, GFP_NOFS);
1137 if (ref_tree) {
1138 if (!ret)
1139 ret = ref_tree_add(ref_tree, 0, 0, 0,
1140 bytenr, count);
1141 if (!ret && ref_tree->unique_refs > 1)
1142 ret = BACKREF_FOUND_SHARED;
1143 }
1144 break;
1145 }
1146 case BTRFS_TREE_BLOCK_REF_KEY:
1147 ret = __add_prelim_ref(prefs, key.offset, NULL,
1148 info_level + 1, 0,
1149 bytenr, 1, GFP_NOFS);
1150 break;
1151 case BTRFS_EXTENT_DATA_REF_KEY: {
1152 struct btrfs_extent_data_ref *dref;
1153 int count;
1154 u64 root;
1155
1156 dref = btrfs_item_ptr(leaf, slot,
1157 struct btrfs_extent_data_ref);
1158 count = btrfs_extent_data_ref_count(leaf, dref);
1159 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1160 dref);
1161 key.type = BTRFS_EXTENT_DATA_KEY;
1162 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1163
1164 if (inum && key.objectid != inum) {
1165 ret = BACKREF_FOUND_SHARED;
1166 break;
1167 }
1168
1169 root = btrfs_extent_data_ref_root(leaf, dref);
1170 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
1171 bytenr, count, GFP_NOFS);
1172 if (ref_tree) {
1173 if (!ret)
1174 ret = ref_tree_add(ref_tree, root,
1175 key.objectid,
1176 key.offset, 0,
1177 count);
1178 if (!ret && ref_tree->unique_refs > 1)
1179 ret = BACKREF_FOUND_SHARED;
1180 }
1181 break;
1182 }
1183 default:
1184 WARN_ON(1);
1185 }
1186 if (ret)
1187 return ret;
1188
1189 }
1190
1191 return ret;
1192 }
1193
1194 /*
1195 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1196 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1197 * indirect refs to their parent bytenr.
1198 * When roots are found, they're added to the roots list
1199 *
1200 * NOTE: This can return values > 0
1201 *
1202 * If time_seq is set to SEQ_LAST, it will not search delayed_refs, and behave
1203 * much like trans == NULL case, the difference only lies in it will not
1204 * commit root.
1205 * The special case is for qgroup to search roots in commit_transaction().
1206 *
1207 * If check_shared is set to 1, any extent has more than one ref item, will
1208 * be returned BACKREF_FOUND_SHARED immediately.
1209 *
1210 * FIXME some caching might speed things up
1211 */
1212 static int find_parent_nodes(struct btrfs_trans_handle *trans,
1213 struct btrfs_fs_info *fs_info, u64 bytenr,
1214 u64 time_seq, struct ulist *refs,
1215 struct ulist *roots, const u64 *extent_item_pos,
1216 u64 root_objectid, u64 inum, int check_shared)
1217 {
1218 struct btrfs_key key;
1219 struct btrfs_path *path;
1220 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1221 struct btrfs_delayed_ref_head *head;
1222 int info_level = 0;
1223 int ret;
1224 struct list_head prefs_delayed;
1225 struct list_head prefs;
1226 struct __prelim_ref *ref;
1227 struct extent_inode_elem *eie = NULL;
1228 struct ref_root *ref_tree = NULL;
1229 u64 total_refs = 0;
1230
1231 INIT_LIST_HEAD(&prefs);
1232 INIT_LIST_HEAD(&prefs_delayed);
1233
1234 key.objectid = bytenr;
1235 key.offset = (u64)-1;
1236 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1237 key.type = BTRFS_METADATA_ITEM_KEY;
1238 else
1239 key.type = BTRFS_EXTENT_ITEM_KEY;
1240
1241 path = btrfs_alloc_path();
1242 if (!path)
1243 return -ENOMEM;
1244 if (!trans) {
1245 path->search_commit_root = 1;
1246 path->skip_locking = 1;
1247 }
1248
1249 if (time_seq == SEQ_LAST)
1250 path->skip_locking = 1;
1251
1252 /*
1253 * grab both a lock on the path and a lock on the delayed ref head.
1254 * We need both to get a consistent picture of how the refs look
1255 * at a specified point in time
1256 */
1257 again:
1258 head = NULL;
1259
1260 if (check_shared) {
1261 if (!ref_tree) {
1262 ref_tree = ref_root_alloc();
1263 if (!ref_tree) {
1264 ret = -ENOMEM;
1265 goto out;
1266 }
1267 } else {
1268 ref_root_fini(ref_tree);
1269 }
1270 }
1271
1272 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
1273 if (ret < 0)
1274 goto out;
1275 BUG_ON(ret == 0);
1276
1277 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1278 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1279 time_seq != SEQ_LAST) {
1280 #else
1281 if (trans && time_seq != SEQ_LAST) {
1282 #endif
1283 /*
1284 * look if there are updates for this ref queued and lock the
1285 * head
1286 */
1287 delayed_refs = &trans->transaction->delayed_refs;
1288 spin_lock(&delayed_refs->lock);
1289 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
1290 if (head) {
1291 if (!mutex_trylock(&head->mutex)) {
1292 refcount_inc(&head->node.refs);
1293 spin_unlock(&delayed_refs->lock);
1294
1295 btrfs_release_path(path);
1296
1297 /*
1298 * Mutex was contended, block until it's
1299 * released and try again
1300 */
1301 mutex_lock(&head->mutex);
1302 mutex_unlock(&head->mutex);
1303 btrfs_put_delayed_ref(&head->node);
1304 goto again;
1305 }
1306 spin_unlock(&delayed_refs->lock);
1307 ret = __add_delayed_refs(head, time_seq,
1308 &prefs_delayed, &total_refs,
1309 inum);
1310 mutex_unlock(&head->mutex);
1311 if (ret)
1312 goto out;
1313 } else {
1314 spin_unlock(&delayed_refs->lock);
1315 }
1316
1317 if (check_shared && !list_empty(&prefs_delayed)) {
1318 /*
1319 * Add all delay_ref to the ref_tree and check if there
1320 * are multiple ref items added.
1321 */
1322 list_for_each_entry(ref, &prefs_delayed, list) {
1323 if (ref->key_for_search.type) {
1324 ret = ref_tree_add(ref_tree,
1325 ref->root_id,
1326 ref->key_for_search.objectid,
1327 ref->key_for_search.offset,
1328 0, ref->count);
1329 if (ret)
1330 goto out;
1331 } else {
1332 ret = ref_tree_add(ref_tree, 0, 0, 0,
1333 ref->parent, ref->count);
1334 if (ret)
1335 goto out;
1336 }
1337
1338 }
1339
1340 if (ref_tree->unique_refs > 1) {
1341 ret = BACKREF_FOUND_SHARED;
1342 goto out;
1343 }
1344
1345 }
1346 }
1347
1348 if (path->slots[0]) {
1349 struct extent_buffer *leaf;
1350 int slot;
1351
1352 path->slots[0]--;
1353 leaf = path->nodes[0];
1354 slot = path->slots[0];
1355 btrfs_item_key_to_cpu(leaf, &key, slot);
1356 if (key.objectid == bytenr &&
1357 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1358 key.type == BTRFS_METADATA_ITEM_KEY)) {
1359 ret = __add_inline_refs(path, bytenr,
1360 &info_level, &prefs,
1361 ref_tree, &total_refs,
1362 inum);
1363 if (ret)
1364 goto out;
1365 ret = __add_keyed_refs(fs_info, path, bytenr,
1366 info_level, &prefs,
1367 ref_tree, inum);
1368 if (ret)
1369 goto out;
1370 }
1371 }
1372 btrfs_release_path(path);
1373
1374 list_splice_init(&prefs_delayed, &prefs);
1375
1376 ret = __add_missing_keys(fs_info, &prefs);
1377 if (ret)
1378 goto out;
1379
1380 __merge_refs(&prefs, MERGE_IDENTICAL_KEYS);
1381
1382 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
1383 extent_item_pos, total_refs,
1384 root_objectid);
1385 if (ret)
1386 goto out;
1387
1388 __merge_refs(&prefs, MERGE_IDENTICAL_PARENTS);
1389
1390 while (!list_empty(&prefs)) {
1391 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1392 WARN_ON(ref->count < 0);
1393 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1394 if (root_objectid && ref->root_id != root_objectid) {
1395 ret = BACKREF_FOUND_SHARED;
1396 goto out;
1397 }
1398
1399 /* no parent == root of tree */
1400 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1401 if (ret < 0)
1402 goto out;
1403 }
1404 if (ref->count && ref->parent) {
1405 if (extent_item_pos && !ref->inode_list &&
1406 ref->level == 0) {
1407 struct extent_buffer *eb;
1408
1409 eb = read_tree_block(fs_info, ref->parent, 0);
1410 if (IS_ERR(eb)) {
1411 ret = PTR_ERR(eb);
1412 goto out;
1413 } else if (!extent_buffer_uptodate(eb)) {
1414 free_extent_buffer(eb);
1415 ret = -EIO;
1416 goto out;
1417 }
1418 btrfs_tree_read_lock(eb);
1419 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1420 ret = find_extent_in_eb(eb, bytenr,
1421 *extent_item_pos, &eie);
1422 btrfs_tree_read_unlock_blocking(eb);
1423 free_extent_buffer(eb);
1424 if (ret < 0)
1425 goto out;
1426 ref->inode_list = eie;
1427 }
1428 ret = ulist_add_merge_ptr(refs, ref->parent,
1429 ref->inode_list,
1430 (void **)&eie, GFP_NOFS);
1431 if (ret < 0)
1432 goto out;
1433 if (!ret && extent_item_pos) {
1434 /*
1435 * we've recorded that parent, so we must extend
1436 * its inode list here
1437 */
1438 BUG_ON(!eie);
1439 while (eie->next)
1440 eie = eie->next;
1441 eie->next = ref->inode_list;
1442 }
1443 eie = NULL;
1444 }
1445 list_del(&ref->list);
1446 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1447 }
1448
1449 out:
1450 btrfs_free_path(path);
1451 ref_root_free(ref_tree);
1452 while (!list_empty(&prefs)) {
1453 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1454 list_del(&ref->list);
1455 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1456 }
1457 while (!list_empty(&prefs_delayed)) {
1458 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
1459 list);
1460 list_del(&ref->list);
1461 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1462 }
1463 if (ret < 0)
1464 free_inode_elem_list(eie);
1465 return ret;
1466 }
1467
1468 static void free_leaf_list(struct ulist *blocks)
1469 {
1470 struct ulist_node *node = NULL;
1471 struct extent_inode_elem *eie;
1472 struct ulist_iterator uiter;
1473
1474 ULIST_ITER_INIT(&uiter);
1475 while ((node = ulist_next(blocks, &uiter))) {
1476 if (!node->aux)
1477 continue;
1478 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1479 free_inode_elem_list(eie);
1480 node->aux = 0;
1481 }
1482
1483 ulist_free(blocks);
1484 }
1485
1486 /*
1487 * Finds all leafs with a reference to the specified combination of bytenr and
1488 * offset. key_list_head will point to a list of corresponding keys (caller must
1489 * free each list element). The leafs will be stored in the leafs ulist, which
1490 * must be freed with ulist_free.
1491 *
1492 * returns 0 on success, <0 on error
1493 */
1494 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1495 struct btrfs_fs_info *fs_info, u64 bytenr,
1496 u64 time_seq, struct ulist **leafs,
1497 const u64 *extent_item_pos)
1498 {
1499 int ret;
1500
1501 *leafs = ulist_alloc(GFP_NOFS);
1502 if (!*leafs)
1503 return -ENOMEM;
1504
1505 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1506 *leafs, NULL, extent_item_pos, 0, 0, 0);
1507 if (ret < 0 && ret != -ENOENT) {
1508 free_leaf_list(*leafs);
1509 return ret;
1510 }
1511
1512 return 0;
1513 }
1514
1515 /*
1516 * walk all backrefs for a given extent to find all roots that reference this
1517 * extent. Walking a backref means finding all extents that reference this
1518 * extent and in turn walk the backrefs of those, too. Naturally this is a
1519 * recursive process, but here it is implemented in an iterative fashion: We
1520 * find all referencing extents for the extent in question and put them on a
1521 * list. In turn, we find all referencing extents for those, further appending
1522 * to the list. The way we iterate the list allows adding more elements after
1523 * the current while iterating. The process stops when we reach the end of the
1524 * list. Found roots are added to the roots list.
1525 *
1526 * returns 0 on success, < 0 on error.
1527 */
1528 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1529 struct btrfs_fs_info *fs_info, u64 bytenr,
1530 u64 time_seq, struct ulist **roots)
1531 {
1532 struct ulist *tmp;
1533 struct ulist_node *node = NULL;
1534 struct ulist_iterator uiter;
1535 int ret;
1536
1537 tmp = ulist_alloc(GFP_NOFS);
1538 if (!tmp)
1539 return -ENOMEM;
1540 *roots = ulist_alloc(GFP_NOFS);
1541 if (!*roots) {
1542 ulist_free(tmp);
1543 return -ENOMEM;
1544 }
1545
1546 ULIST_ITER_INIT(&uiter);
1547 while (1) {
1548 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1549 tmp, *roots, NULL, 0, 0, 0);
1550 if (ret < 0 && ret != -ENOENT) {
1551 ulist_free(tmp);
1552 ulist_free(*roots);
1553 return ret;
1554 }
1555 node = ulist_next(tmp, &uiter);
1556 if (!node)
1557 break;
1558 bytenr = node->val;
1559 cond_resched();
1560 }
1561
1562 ulist_free(tmp);
1563 return 0;
1564 }
1565
1566 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1567 struct btrfs_fs_info *fs_info, u64 bytenr,
1568 u64 time_seq, struct ulist **roots)
1569 {
1570 int ret;
1571
1572 if (!trans)
1573 down_read(&fs_info->commit_root_sem);
1574 ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
1575 if (!trans)
1576 up_read(&fs_info->commit_root_sem);
1577 return ret;
1578 }
1579
1580 /**
1581 * btrfs_check_shared - tell us whether an extent is shared
1582 *
1583 * @trans: optional trans handle
1584 *
1585 * btrfs_check_shared uses the backref walking code but will short
1586 * circuit as soon as it finds a root or inode that doesn't match the
1587 * one passed in. This provides a significant performance benefit for
1588 * callers (such as fiemap) which want to know whether the extent is
1589 * shared but do not need a ref count.
1590 *
1591 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1592 */
1593 int btrfs_check_shared(struct btrfs_trans_handle *trans,
1594 struct btrfs_fs_info *fs_info, u64 root_objectid,
1595 u64 inum, u64 bytenr)
1596 {
1597 struct ulist *tmp = NULL;
1598 struct ulist *roots = NULL;
1599 struct ulist_iterator uiter;
1600 struct ulist_node *node;
1601 struct seq_list elem = SEQ_LIST_INIT(elem);
1602 int ret = 0;
1603
1604 tmp = ulist_alloc(GFP_NOFS);
1605 roots = ulist_alloc(GFP_NOFS);
1606 if (!tmp || !roots) {
1607 ulist_free(tmp);
1608 ulist_free(roots);
1609 return -ENOMEM;
1610 }
1611
1612 if (trans)
1613 btrfs_get_tree_mod_seq(fs_info, &elem);
1614 else
1615 down_read(&fs_info->commit_root_sem);
1616 ULIST_ITER_INIT(&uiter);
1617 while (1) {
1618 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1619 roots, NULL, root_objectid, inum, 1);
1620 if (ret == BACKREF_FOUND_SHARED) {
1621 /* this is the only condition under which we return 1 */
1622 ret = 1;
1623 break;
1624 }
1625 if (ret < 0 && ret != -ENOENT)
1626 break;
1627 ret = 0;
1628 node = ulist_next(tmp, &uiter);
1629 if (!node)
1630 break;
1631 bytenr = node->val;
1632 cond_resched();
1633 }
1634 if (trans)
1635 btrfs_put_tree_mod_seq(fs_info, &elem);
1636 else
1637 up_read(&fs_info->commit_root_sem);
1638 ulist_free(tmp);
1639 ulist_free(roots);
1640 return ret;
1641 }
1642
1643 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1644 u64 start_off, struct btrfs_path *path,
1645 struct btrfs_inode_extref **ret_extref,
1646 u64 *found_off)
1647 {
1648 int ret, slot;
1649 struct btrfs_key key;
1650 struct btrfs_key found_key;
1651 struct btrfs_inode_extref *extref;
1652 struct extent_buffer *leaf;
1653 unsigned long ptr;
1654
1655 key.objectid = inode_objectid;
1656 key.type = BTRFS_INODE_EXTREF_KEY;
1657 key.offset = start_off;
1658
1659 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1660 if (ret < 0)
1661 return ret;
1662
1663 while (1) {
1664 leaf = path->nodes[0];
1665 slot = path->slots[0];
1666 if (slot >= btrfs_header_nritems(leaf)) {
1667 /*
1668 * If the item at offset is not found,
1669 * btrfs_search_slot will point us to the slot
1670 * where it should be inserted. In our case
1671 * that will be the slot directly before the
1672 * next INODE_REF_KEY_V2 item. In the case
1673 * that we're pointing to the last slot in a
1674 * leaf, we must move one leaf over.
1675 */
1676 ret = btrfs_next_leaf(root, path);
1677 if (ret) {
1678 if (ret >= 1)
1679 ret = -ENOENT;
1680 break;
1681 }
1682 continue;
1683 }
1684
1685 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1686
1687 /*
1688 * Check that we're still looking at an extended ref key for
1689 * this particular objectid. If we have different
1690 * objectid or type then there are no more to be found
1691 * in the tree and we can exit.
1692 */
1693 ret = -ENOENT;
1694 if (found_key.objectid != inode_objectid)
1695 break;
1696 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1697 break;
1698
1699 ret = 0;
1700 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1701 extref = (struct btrfs_inode_extref *)ptr;
1702 *ret_extref = extref;
1703 if (found_off)
1704 *found_off = found_key.offset;
1705 break;
1706 }
1707
1708 return ret;
1709 }
1710
1711 /*
1712 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1713 * Elements of the path are separated by '/' and the path is guaranteed to be
1714 * 0-terminated. the path is only given within the current file system.
1715 * Therefore, it never starts with a '/'. the caller is responsible to provide
1716 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1717 * the start point of the resulting string is returned. this pointer is within
1718 * dest, normally.
1719 * in case the path buffer would overflow, the pointer is decremented further
1720 * as if output was written to the buffer, though no more output is actually
1721 * generated. that way, the caller can determine how much space would be
1722 * required for the path to fit into the buffer. in that case, the returned
1723 * value will be smaller than dest. callers must check this!
1724 */
1725 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1726 u32 name_len, unsigned long name_off,
1727 struct extent_buffer *eb_in, u64 parent,
1728 char *dest, u32 size)
1729 {
1730 int slot;
1731 u64 next_inum;
1732 int ret;
1733 s64 bytes_left = ((s64)size) - 1;
1734 struct extent_buffer *eb = eb_in;
1735 struct btrfs_key found_key;
1736 int leave_spinning = path->leave_spinning;
1737 struct btrfs_inode_ref *iref;
1738
1739 if (bytes_left >= 0)
1740 dest[bytes_left] = '\0';
1741
1742 path->leave_spinning = 1;
1743 while (1) {
1744 bytes_left -= name_len;
1745 if (bytes_left >= 0)
1746 read_extent_buffer(eb, dest + bytes_left,
1747 name_off, name_len);
1748 if (eb != eb_in) {
1749 if (!path->skip_locking)
1750 btrfs_tree_read_unlock_blocking(eb);
1751 free_extent_buffer(eb);
1752 }
1753 ret = btrfs_find_item(fs_root, path, parent, 0,
1754 BTRFS_INODE_REF_KEY, &found_key);
1755 if (ret > 0)
1756 ret = -ENOENT;
1757 if (ret)
1758 break;
1759
1760 next_inum = found_key.offset;
1761
1762 /* regular exit ahead */
1763 if (parent == next_inum)
1764 break;
1765
1766 slot = path->slots[0];
1767 eb = path->nodes[0];
1768 /* make sure we can use eb after releasing the path */
1769 if (eb != eb_in) {
1770 if (!path->skip_locking)
1771 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1772 path->nodes[0] = NULL;
1773 path->locks[0] = 0;
1774 }
1775 btrfs_release_path(path);
1776 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1777
1778 name_len = btrfs_inode_ref_name_len(eb, iref);
1779 name_off = (unsigned long)(iref + 1);
1780
1781 parent = next_inum;
1782 --bytes_left;
1783 if (bytes_left >= 0)
1784 dest[bytes_left] = '/';
1785 }
1786
1787 btrfs_release_path(path);
1788 path->leave_spinning = leave_spinning;
1789
1790 if (ret)
1791 return ERR_PTR(ret);
1792
1793 return dest + bytes_left;
1794 }
1795
1796 /*
1797 * this makes the path point to (logical EXTENT_ITEM *)
1798 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1799 * tree blocks and <0 on error.
1800 */
1801 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1802 struct btrfs_path *path, struct btrfs_key *found_key,
1803 u64 *flags_ret)
1804 {
1805 int ret;
1806 u64 flags;
1807 u64 size = 0;
1808 u32 item_size;
1809 struct extent_buffer *eb;
1810 struct btrfs_extent_item *ei;
1811 struct btrfs_key key;
1812
1813 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1814 key.type = BTRFS_METADATA_ITEM_KEY;
1815 else
1816 key.type = BTRFS_EXTENT_ITEM_KEY;
1817 key.objectid = logical;
1818 key.offset = (u64)-1;
1819
1820 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1821 if (ret < 0)
1822 return ret;
1823
1824 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1825 if (ret) {
1826 if (ret > 0)
1827 ret = -ENOENT;
1828 return ret;
1829 }
1830 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1831 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1832 size = fs_info->nodesize;
1833 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1834 size = found_key->offset;
1835
1836 if (found_key->objectid > logical ||
1837 found_key->objectid + size <= logical) {
1838 btrfs_debug(fs_info,
1839 "logical %llu is not within any extent", logical);
1840 return -ENOENT;
1841 }
1842
1843 eb = path->nodes[0];
1844 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1845 BUG_ON(item_size < sizeof(*ei));
1846
1847 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1848 flags = btrfs_extent_flags(eb, ei);
1849
1850 btrfs_debug(fs_info,
1851 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1852 logical, logical - found_key->objectid, found_key->objectid,
1853 found_key->offset, flags, item_size);
1854
1855 WARN_ON(!flags_ret);
1856 if (flags_ret) {
1857 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1858 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1859 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1860 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1861 else
1862 BUG_ON(1);
1863 return 0;
1864 }
1865
1866 return -EIO;
1867 }
1868
1869 /*
1870 * helper function to iterate extent inline refs. ptr must point to a 0 value
1871 * for the first call and may be modified. it is used to track state.
1872 * if more refs exist, 0 is returned and the next call to
1873 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1874 * next ref. after the last ref was processed, 1 is returned.
1875 * returns <0 on error
1876 */
1877 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1878 struct btrfs_key *key,
1879 struct btrfs_extent_item *ei, u32 item_size,
1880 struct btrfs_extent_inline_ref **out_eiref,
1881 int *out_type)
1882 {
1883 unsigned long end;
1884 u64 flags;
1885 struct btrfs_tree_block_info *info;
1886
1887 if (!*ptr) {
1888 /* first call */
1889 flags = btrfs_extent_flags(eb, ei);
1890 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1891 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1892 /* a skinny metadata extent */
1893 *out_eiref =
1894 (struct btrfs_extent_inline_ref *)(ei + 1);
1895 } else {
1896 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1897 info = (struct btrfs_tree_block_info *)(ei + 1);
1898 *out_eiref =
1899 (struct btrfs_extent_inline_ref *)(info + 1);
1900 }
1901 } else {
1902 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1903 }
1904 *ptr = (unsigned long)*out_eiref;
1905 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1906 return -ENOENT;
1907 }
1908
1909 end = (unsigned long)ei + item_size;
1910 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1911 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1912
1913 *ptr += btrfs_extent_inline_ref_size(*out_type);
1914 WARN_ON(*ptr > end);
1915 if (*ptr == end)
1916 return 1; /* last */
1917
1918 return 0;
1919 }
1920
1921 /*
1922 * reads the tree block backref for an extent. tree level and root are returned
1923 * through out_level and out_root. ptr must point to a 0 value for the first
1924 * call and may be modified (see __get_extent_inline_ref comment).
1925 * returns 0 if data was provided, 1 if there was no more data to provide or
1926 * <0 on error.
1927 */
1928 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1929 struct btrfs_key *key, struct btrfs_extent_item *ei,
1930 u32 item_size, u64 *out_root, u8 *out_level)
1931 {
1932 int ret;
1933 int type;
1934 struct btrfs_extent_inline_ref *eiref;
1935
1936 if (*ptr == (unsigned long)-1)
1937 return 1;
1938
1939 while (1) {
1940 ret = __get_extent_inline_ref(ptr, eb, key, ei, item_size,
1941 &eiref, &type);
1942 if (ret < 0)
1943 return ret;
1944
1945 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1946 type == BTRFS_SHARED_BLOCK_REF_KEY)
1947 break;
1948
1949 if (ret == 1)
1950 return 1;
1951 }
1952
1953 /* we can treat both ref types equally here */
1954 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1955
1956 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1957 struct btrfs_tree_block_info *info;
1958
1959 info = (struct btrfs_tree_block_info *)(ei + 1);
1960 *out_level = btrfs_tree_block_level(eb, info);
1961 } else {
1962 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1963 *out_level = (u8)key->offset;
1964 }
1965
1966 if (ret == 1)
1967 *ptr = (unsigned long)-1;
1968
1969 return 0;
1970 }
1971
1972 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1973 struct extent_inode_elem *inode_list,
1974 u64 root, u64 extent_item_objectid,
1975 iterate_extent_inodes_t *iterate, void *ctx)
1976 {
1977 struct extent_inode_elem *eie;
1978 int ret = 0;
1979
1980 for (eie = inode_list; eie; eie = eie->next) {
1981 btrfs_debug(fs_info,
1982 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1983 extent_item_objectid, eie->inum,
1984 eie->offset, root);
1985 ret = iterate(eie->inum, eie->offset, root, ctx);
1986 if (ret) {
1987 btrfs_debug(fs_info,
1988 "stopping iteration for %llu due to ret=%d",
1989 extent_item_objectid, ret);
1990 break;
1991 }
1992 }
1993
1994 return ret;
1995 }
1996
1997 /*
1998 * calls iterate() for every inode that references the extent identified by
1999 * the given parameters.
2000 * when the iterator function returns a non-zero value, iteration stops.
2001 */
2002 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
2003 u64 extent_item_objectid, u64 extent_item_pos,
2004 int search_commit_root,
2005 iterate_extent_inodes_t *iterate, void *ctx)
2006 {
2007 int ret;
2008 struct btrfs_trans_handle *trans = NULL;
2009 struct ulist *refs = NULL;
2010 struct ulist *roots = NULL;
2011 struct ulist_node *ref_node = NULL;
2012 struct ulist_node *root_node = NULL;
2013 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
2014 struct ulist_iterator ref_uiter;
2015 struct ulist_iterator root_uiter;
2016
2017 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
2018 extent_item_objectid);
2019
2020 if (!search_commit_root) {
2021 trans = btrfs_join_transaction(fs_info->extent_root);
2022 if (IS_ERR(trans))
2023 return PTR_ERR(trans);
2024 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
2025 } else {
2026 down_read(&fs_info->commit_root_sem);
2027 }
2028
2029 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
2030 tree_mod_seq_elem.seq, &refs,
2031 &extent_item_pos);
2032 if (ret)
2033 goto out;
2034
2035 ULIST_ITER_INIT(&ref_uiter);
2036 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
2037 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
2038 tree_mod_seq_elem.seq, &roots);
2039 if (ret)
2040 break;
2041 ULIST_ITER_INIT(&root_uiter);
2042 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
2043 btrfs_debug(fs_info,
2044 "root %llu references leaf %llu, data list %#llx",
2045 root_node->val, ref_node->val,
2046 ref_node->aux);
2047 ret = iterate_leaf_refs(fs_info,
2048 (struct extent_inode_elem *)
2049 (uintptr_t)ref_node->aux,
2050 root_node->val,
2051 extent_item_objectid,
2052 iterate, ctx);
2053 }
2054 ulist_free(roots);
2055 }
2056
2057 free_leaf_list(refs);
2058 out:
2059 if (!search_commit_root) {
2060 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
2061 btrfs_end_transaction(trans);
2062 } else {
2063 up_read(&fs_info->commit_root_sem);
2064 }
2065
2066 return ret;
2067 }
2068
2069 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
2070 struct btrfs_path *path,
2071 iterate_extent_inodes_t *iterate, void *ctx)
2072 {
2073 int ret;
2074 u64 extent_item_pos;
2075 u64 flags = 0;
2076 struct btrfs_key found_key;
2077 int search_commit_root = path->search_commit_root;
2078
2079 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
2080 btrfs_release_path(path);
2081 if (ret < 0)
2082 return ret;
2083 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2084 return -EINVAL;
2085
2086 extent_item_pos = logical - found_key.objectid;
2087 ret = iterate_extent_inodes(fs_info, found_key.objectid,
2088 extent_item_pos, search_commit_root,
2089 iterate, ctx);
2090
2091 return ret;
2092 }
2093
2094 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
2095 struct extent_buffer *eb, void *ctx);
2096
2097 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
2098 struct btrfs_path *path,
2099 iterate_irefs_t *iterate, void *ctx)
2100 {
2101 int ret = 0;
2102 int slot;
2103 u32 cur;
2104 u32 len;
2105 u32 name_len;
2106 u64 parent = 0;
2107 int found = 0;
2108 struct extent_buffer *eb;
2109 struct btrfs_item *item;
2110 struct btrfs_inode_ref *iref;
2111 struct btrfs_key found_key;
2112
2113 while (!ret) {
2114 ret = btrfs_find_item(fs_root, path, inum,
2115 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2116 &found_key);
2117
2118 if (ret < 0)
2119 break;
2120 if (ret) {
2121 ret = found ? 0 : -ENOENT;
2122 break;
2123 }
2124 ++found;
2125
2126 parent = found_key.offset;
2127 slot = path->slots[0];
2128 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2129 if (!eb) {
2130 ret = -ENOMEM;
2131 break;
2132 }
2133 extent_buffer_get(eb);
2134 btrfs_tree_read_lock(eb);
2135 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2136 btrfs_release_path(path);
2137
2138 item = btrfs_item_nr(slot);
2139 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2140
2141 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
2142 name_len = btrfs_inode_ref_name_len(eb, iref);
2143 /* path must be released before calling iterate()! */
2144 btrfs_debug(fs_root->fs_info,
2145 "following ref at offset %u for inode %llu in tree %llu",
2146 cur, found_key.objectid, fs_root->objectid);
2147 ret = iterate(parent, name_len,
2148 (unsigned long)(iref + 1), eb, ctx);
2149 if (ret)
2150 break;
2151 len = sizeof(*iref) + name_len;
2152 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2153 }
2154 btrfs_tree_read_unlock_blocking(eb);
2155 free_extent_buffer(eb);
2156 }
2157
2158 btrfs_release_path(path);
2159
2160 return ret;
2161 }
2162
2163 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
2164 struct btrfs_path *path,
2165 iterate_irefs_t *iterate, void *ctx)
2166 {
2167 int ret;
2168 int slot;
2169 u64 offset = 0;
2170 u64 parent;
2171 int found = 0;
2172 struct extent_buffer *eb;
2173 struct btrfs_inode_extref *extref;
2174 u32 item_size;
2175 u32 cur_offset;
2176 unsigned long ptr;
2177
2178 while (1) {
2179 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2180 &offset);
2181 if (ret < 0)
2182 break;
2183 if (ret) {
2184 ret = found ? 0 : -ENOENT;
2185 break;
2186 }
2187 ++found;
2188
2189 slot = path->slots[0];
2190 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2191 if (!eb) {
2192 ret = -ENOMEM;
2193 break;
2194 }
2195 extent_buffer_get(eb);
2196
2197 btrfs_tree_read_lock(eb);
2198 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2199 btrfs_release_path(path);
2200
2201 item_size = btrfs_item_size_nr(eb, slot);
2202 ptr = btrfs_item_ptr_offset(eb, slot);
2203 cur_offset = 0;
2204
2205 while (cur_offset < item_size) {
2206 u32 name_len;
2207
2208 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2209 parent = btrfs_inode_extref_parent(eb, extref);
2210 name_len = btrfs_inode_extref_name_len(eb, extref);
2211 ret = iterate(parent, name_len,
2212 (unsigned long)&extref->name, eb, ctx);
2213 if (ret)
2214 break;
2215
2216 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2217 cur_offset += sizeof(*extref);
2218 }
2219 btrfs_tree_read_unlock_blocking(eb);
2220 free_extent_buffer(eb);
2221
2222 offset++;
2223 }
2224
2225 btrfs_release_path(path);
2226
2227 return ret;
2228 }
2229
2230 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
2231 struct btrfs_path *path, iterate_irefs_t *iterate,
2232 void *ctx)
2233 {
2234 int ret;
2235 int found_refs = 0;
2236
2237 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
2238 if (!ret)
2239 ++found_refs;
2240 else if (ret != -ENOENT)
2241 return ret;
2242
2243 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
2244 if (ret == -ENOENT && found_refs)
2245 return 0;
2246
2247 return ret;
2248 }
2249
2250 /*
2251 * returns 0 if the path could be dumped (probably truncated)
2252 * returns <0 in case of an error
2253 */
2254 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2255 struct extent_buffer *eb, void *ctx)
2256 {
2257 struct inode_fs_paths *ipath = ctx;
2258 char *fspath;
2259 char *fspath_min;
2260 int i = ipath->fspath->elem_cnt;
2261 const int s_ptr = sizeof(char *);
2262 u32 bytes_left;
2263
2264 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2265 ipath->fspath->bytes_left - s_ptr : 0;
2266
2267 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2268 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2269 name_off, eb, inum, fspath_min, bytes_left);
2270 if (IS_ERR(fspath))
2271 return PTR_ERR(fspath);
2272
2273 if (fspath > fspath_min) {
2274 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2275 ++ipath->fspath->elem_cnt;
2276 ipath->fspath->bytes_left = fspath - fspath_min;
2277 } else {
2278 ++ipath->fspath->elem_missed;
2279 ipath->fspath->bytes_missing += fspath_min - fspath;
2280 ipath->fspath->bytes_left = 0;
2281 }
2282
2283 return 0;
2284 }
2285
2286 /*
2287 * this dumps all file system paths to the inode into the ipath struct, provided
2288 * is has been created large enough. each path is zero-terminated and accessed
2289 * from ipath->fspath->val[i].
2290 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2291 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2292 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2293 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2294 * have been needed to return all paths.
2295 */
2296 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2297 {
2298 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
2299 inode_to_path, ipath);
2300 }
2301
2302 struct btrfs_data_container *init_data_container(u32 total_bytes)
2303 {
2304 struct btrfs_data_container *data;
2305 size_t alloc_bytes;
2306
2307 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2308 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2309 if (!data)
2310 return ERR_PTR(-ENOMEM);
2311
2312 if (total_bytes >= sizeof(*data)) {
2313 data->bytes_left = total_bytes - sizeof(*data);
2314 data->bytes_missing = 0;
2315 } else {
2316 data->bytes_missing = sizeof(*data) - total_bytes;
2317 data->bytes_left = 0;
2318 }
2319
2320 data->elem_cnt = 0;
2321 data->elem_missed = 0;
2322
2323 return data;
2324 }
2325
2326 /*
2327 * allocates space to return multiple file system paths for an inode.
2328 * total_bytes to allocate are passed, note that space usable for actual path
2329 * information will be total_bytes - sizeof(struct inode_fs_paths).
2330 * the returned pointer must be freed with free_ipath() in the end.
2331 */
2332 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2333 struct btrfs_path *path)
2334 {
2335 struct inode_fs_paths *ifp;
2336 struct btrfs_data_container *fspath;
2337
2338 fspath = init_data_container(total_bytes);
2339 if (IS_ERR(fspath))
2340 return (void *)fspath;
2341
2342 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2343 if (!ifp) {
2344 kvfree(fspath);
2345 return ERR_PTR(-ENOMEM);
2346 }
2347
2348 ifp->btrfs_path = path;
2349 ifp->fspath = fspath;
2350 ifp->fs_root = fs_root;
2351
2352 return ifp;
2353 }
2354
2355 void free_ipath(struct inode_fs_paths *ipath)
2356 {
2357 if (!ipath)
2358 return;
2359 kvfree(ipath->fspath);
2360 kfree(ipath);
2361 }
Linux with added FPC-III support