projects / deliverable / linux.git / blob
? search:
summary | shortlog | log | commit | commitdiff | tree
blame | history | raw | HEAD
Merge branch 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszere...
[deliverable/linux.git] / fs / btrfs / backref.c
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 "ctree.h"
21 #include "disk-io.h"
22 #include "backref.h"
23 #include "ulist.h"
24 #include "transaction.h"
25 #include "delayed-ref.h"
26 #include "locking.h"
27
28 /* Just an arbitrary number so we can be sure this happened */
29 #define BACKREF_FOUND_SHARED 6
30
31 struct extent_inode_elem {
32 u64 inum;
33 u64 offset;
34 struct extent_inode_elem *next;
35 };
36
37 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
38 struct btrfs_file_extent_item *fi,
39 u64 extent_item_pos,
40 struct extent_inode_elem **eie)
41 {
42 u64 offset = 0;
43 struct extent_inode_elem *e;
44
45 if (!btrfs_file_extent_compression(eb, fi) &&
46 !btrfs_file_extent_encryption(eb, fi) &&
47 !btrfs_file_extent_other_encoding(eb, fi)) {
48 u64 data_offset;
49 u64 data_len;
50
51 data_offset = btrfs_file_extent_offset(eb, fi);
52 data_len = btrfs_file_extent_num_bytes(eb, fi);
53
54 if (extent_item_pos < data_offset ||
55 extent_item_pos >= data_offset + data_len)
56 return 1;
57 offset = extent_item_pos - data_offset;
58 }
59
60 e = kmalloc(sizeof(*e), GFP_NOFS);
61 if (!e)
62 return -ENOMEM;
63
64 e->next = *eie;
65 e->inum = key->objectid;
66 e->offset = key->offset + offset;
67 *eie = e;
68
69 return 0;
70 }
71
72 static void free_inode_elem_list(struct extent_inode_elem *eie)
73 {
74 struct extent_inode_elem *eie_next;
75
76 for (; eie; eie = eie_next) {
77 eie_next = eie->next;
78 kfree(eie);
79 }
80 }
81
82 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
83 u64 extent_item_pos,
84 struct extent_inode_elem **eie)
85 {
86 u64 disk_byte;
87 struct btrfs_key key;
88 struct btrfs_file_extent_item *fi;
89 int slot;
90 int nritems;
91 int extent_type;
92 int ret;
93
94 /*
95 * from the shared data ref, we only have the leaf but we need
96 * the key. thus, we must look into all items and see that we
97 * find one (some) with a reference to our extent item.
98 */
99 nritems = btrfs_header_nritems(eb);
100 for (slot = 0; slot < nritems; ++slot) {
101 btrfs_item_key_to_cpu(eb, &key, slot);
102 if (key.type != BTRFS_EXTENT_DATA_KEY)
103 continue;
104 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
105 extent_type = btrfs_file_extent_type(eb, fi);
106 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
107 continue;
108 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
109 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
110 if (disk_byte != wanted_disk_byte)
111 continue;
112
113 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
114 if (ret < 0)
115 return ret;
116 }
117
118 return 0;
119 }
120
121 /*
122 * this structure records all encountered refs on the way up to the root
123 */
124 struct __prelim_ref {
125 struct list_head list;
126 u64 root_id;
127 struct btrfs_key key_for_search;
128 int level;
129 int count;
130 struct extent_inode_elem *inode_list;
131 u64 parent;
132 u64 wanted_disk_byte;
133 };
134
135 static struct kmem_cache *btrfs_prelim_ref_cache;
136
137 int __init btrfs_prelim_ref_init(void)
138 {
139 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
140 sizeof(struct __prelim_ref),
141 0,
142 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
143 NULL);
144 if (!btrfs_prelim_ref_cache)
145 return -ENOMEM;
146 return 0;
147 }
148
149 void btrfs_prelim_ref_exit(void)
150 {
151 if (btrfs_prelim_ref_cache)
152 kmem_cache_destroy(btrfs_prelim_ref_cache);
153 }
154
155 /*
156 * the rules for all callers of this function are:
157 * - obtaining the parent is the goal
158 * - if you add a key, you must know that it is a correct key
159 * - if you cannot add the parent or a correct key, then we will look into the
160 * block later to set a correct key
161 *
162 * delayed refs
163 * ============
164 * backref type | shared | indirect | shared | indirect
165 * information | tree | tree | data | data
166 * --------------------+--------+----------+--------+----------
167 * parent logical | y | - | - | -
168 * key to resolve | - | y | y | y
169 * tree block logical | - | - | - | -
170 * root for resolving | y | y | y | y
171 *
172 * - column 1: we've the parent -> done
173 * - column 2, 3, 4: we use the key to find the parent
174 *
175 * on disk refs (inline or keyed)
176 * ==============================
177 * backref type | shared | indirect | shared | indirect
178 * information | tree | tree | data | data
179 * --------------------+--------+----------+--------+----------
180 * parent logical | y | - | y | -
181 * key to resolve | - | - | - | y
182 * tree block logical | y | y | y | y
183 * root for resolving | - | y | y | y
184 *
185 * - column 1, 3: we've the parent -> done
186 * - column 2: we take the first key from the block to find the parent
187 * (see __add_missing_keys)
188 * - column 4: we use the key to find the parent
189 *
190 * additional information that's available but not required to find the parent
191 * block might help in merging entries to gain some speed.
192 */
193
194 static int __add_prelim_ref(struct list_head *head, u64 root_id,
195 struct btrfs_key *key, int level,
196 u64 parent, u64 wanted_disk_byte, int count,
197 gfp_t gfp_mask)
198 {
199 struct __prelim_ref *ref;
200
201 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
202 return 0;
203
204 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
205 if (!ref)
206 return -ENOMEM;
207
208 ref->root_id = root_id;
209 if (key)
210 ref->key_for_search = *key;
211 else
212 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
213
214 ref->inode_list = NULL;
215 ref->level = level;
216 ref->count = count;
217 ref->parent = parent;
218 ref->wanted_disk_byte = wanted_disk_byte;
219 list_add_tail(&ref->list, head);
220
221 return 0;
222 }
223
224 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
225 struct ulist *parents, struct __prelim_ref *ref,
226 int level, u64 time_seq, const u64 *extent_item_pos,
227 u64 total_refs)
228 {
229 int ret = 0;
230 int slot;
231 struct extent_buffer *eb;
232 struct btrfs_key key;
233 struct btrfs_key *key_for_search = &ref->key_for_search;
234 struct btrfs_file_extent_item *fi;
235 struct extent_inode_elem *eie = NULL, *old = NULL;
236 u64 disk_byte;
237 u64 wanted_disk_byte = ref->wanted_disk_byte;
238 u64 count = 0;
239
240 if (level != 0) {
241 eb = path->nodes[level];
242 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
243 if (ret < 0)
244 return ret;
245 return 0;
246 }
247
248 /*
249 * We normally enter this function with the path already pointing to
250 * the first item to check. But sometimes, we may enter it with
251 * slot==nritems. In that case, go to the next leaf before we continue.
252 */
253 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
254 ret = btrfs_next_old_leaf(root, path, time_seq);
255
256 while (!ret && count < total_refs) {
257 eb = path->nodes[0];
258 slot = path->slots[0];
259
260 btrfs_item_key_to_cpu(eb, &key, slot);
261
262 if (key.objectid != key_for_search->objectid ||
263 key.type != BTRFS_EXTENT_DATA_KEY)
264 break;
265
266 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
267 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
268
269 if (disk_byte == wanted_disk_byte) {
270 eie = NULL;
271 old = NULL;
272 count++;
273 if (extent_item_pos) {
274 ret = check_extent_in_eb(&key, eb, fi,
275 *extent_item_pos,
276 &eie);
277 if (ret < 0)
278 break;
279 }
280 if (ret > 0)
281 goto next;
282 ret = ulist_add_merge_ptr(parents, eb->start,
283 eie, (void **)&old, GFP_NOFS);
284 if (ret < 0)
285 break;
286 if (!ret && extent_item_pos) {
287 while (old->next)
288 old = old->next;
289 old->next = eie;
290 }
291 eie = NULL;
292 }
293 next:
294 ret = btrfs_next_old_item(root, path, time_seq);
295 }
296
297 if (ret > 0)
298 ret = 0;
299 else if (ret < 0)
300 free_inode_elem_list(eie);
301 return ret;
302 }
303
304 /*
305 * resolve an indirect backref in the form (root_id, key, level)
306 * to a logical address
307 */
308 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
309 struct btrfs_path *path, u64 time_seq,
310 struct __prelim_ref *ref,
311 struct ulist *parents,
312 const u64 *extent_item_pos, u64 total_refs)
313 {
314 struct btrfs_root *root;
315 struct btrfs_key root_key;
316 struct extent_buffer *eb;
317 int ret = 0;
318 int root_level;
319 int level = ref->level;
320 int index;
321
322 root_key.objectid = ref->root_id;
323 root_key.type = BTRFS_ROOT_ITEM_KEY;
324 root_key.offset = (u64)-1;
325
326 index = srcu_read_lock(&fs_info->subvol_srcu);
327
328 root = btrfs_read_fs_root_no_name(fs_info, &root_key);
329 if (IS_ERR(root)) {
330 srcu_read_unlock(&fs_info->subvol_srcu, index);
331 ret = PTR_ERR(root);
332 goto out;
333 }
334
335 if (path->search_commit_root)
336 root_level = btrfs_header_level(root->commit_root);
337 else
338 root_level = btrfs_old_root_level(root, time_seq);
339
340 if (root_level + 1 == level) {
341 srcu_read_unlock(&fs_info->subvol_srcu, index);
342 goto out;
343 }
344
345 path->lowest_level = level;
346 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
347
348 /* root node has been locked, we can release @subvol_srcu safely here */
349 srcu_read_unlock(&fs_info->subvol_srcu, index);
350
351 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
352 "%d for key (%llu %u %llu)\n",
353 ref->root_id, level, ref->count, ret,
354 ref->key_for_search.objectid, ref->key_for_search.type,
355 ref->key_for_search.offset);
356 if (ret < 0)
357 goto out;
358
359 eb = path->nodes[level];
360 while (!eb) {
361 if (WARN_ON(!level)) {
362 ret = 1;
363 goto out;
364 }
365 level--;
366 eb = path->nodes[level];
367 }
368
369 ret = add_all_parents(root, path, parents, ref, level, time_seq,
370 extent_item_pos, total_refs);
371 out:
372 path->lowest_level = 0;
373 btrfs_release_path(path);
374 return ret;
375 }
376
377 /*
378 * resolve all indirect backrefs from the list
379 */
380 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
381 struct btrfs_path *path, u64 time_seq,
382 struct list_head *head,
383 const u64 *extent_item_pos, u64 total_refs,
384 u64 root_objectid)
385 {
386 int err;
387 int ret = 0;
388 struct __prelim_ref *ref;
389 struct __prelim_ref *ref_safe;
390 struct __prelim_ref *new_ref;
391 struct ulist *parents;
392 struct ulist_node *node;
393 struct ulist_iterator uiter;
394
395 parents = ulist_alloc(GFP_NOFS);
396 if (!parents)
397 return -ENOMEM;
398
399 /*
400 * _safe allows us to insert directly after the current item without
401 * iterating over the newly inserted items.
402 * we're also allowed to re-assign ref during iteration.
403 */
404 list_for_each_entry_safe(ref, ref_safe, head, list) {
405 if (ref->parent) /* already direct */
406 continue;
407 if (ref->count == 0)
408 continue;
409 if (root_objectid && ref->root_id != root_objectid) {
410 ret = BACKREF_FOUND_SHARED;
411 goto out;
412 }
413 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
414 parents, extent_item_pos,
415 total_refs);
416 /*
417 * we can only tolerate ENOENT,otherwise,we should catch error
418 * and return directly.
419 */
420 if (err == -ENOENT) {
421 continue;
422 } else if (err) {
423 ret = err;
424 goto out;
425 }
426
427 /* we put the first parent into the ref at hand */
428 ULIST_ITER_INIT(&uiter);
429 node = ulist_next(parents, &uiter);
430 ref->parent = node ? node->val : 0;
431 ref->inode_list = node ?
432 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
433
434 /* additional parents require new refs being added here */
435 while ((node = ulist_next(parents, &uiter))) {
436 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
437 GFP_NOFS);
438 if (!new_ref) {
439 ret = -ENOMEM;
440 goto out;
441 }
442 memcpy(new_ref, ref, sizeof(*ref));
443 new_ref->parent = node->val;
444 new_ref->inode_list = (struct extent_inode_elem *)
445 (uintptr_t)node->aux;
446 list_add(&new_ref->list, &ref->list);
447 }
448 ulist_reinit(parents);
449 }
450 out:
451 ulist_free(parents);
452 return ret;
453 }
454
455 static inline int ref_for_same_block(struct __prelim_ref *ref1,
456 struct __prelim_ref *ref2)
457 {
458 if (ref1->level != ref2->level)
459 return 0;
460 if (ref1->root_id != ref2->root_id)
461 return 0;
462 if (ref1->key_for_search.type != ref2->key_for_search.type)
463 return 0;
464 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
465 return 0;
466 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
467 return 0;
468 if (ref1->parent != ref2->parent)
469 return 0;
470
471 return 1;
472 }
473
474 /*
475 * read tree blocks and add keys where required.
476 */
477 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
478 struct list_head *head)
479 {
480 struct list_head *pos;
481 struct extent_buffer *eb;
482
483 list_for_each(pos, head) {
484 struct __prelim_ref *ref;
485 ref = list_entry(pos, struct __prelim_ref, list);
486
487 if (ref->parent)
488 continue;
489 if (ref->key_for_search.type)
490 continue;
491 BUG_ON(!ref->wanted_disk_byte);
492 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
493 0);
494 if (!eb || !extent_buffer_uptodate(eb)) {
495 free_extent_buffer(eb);
496 return -EIO;
497 }
498 btrfs_tree_read_lock(eb);
499 if (btrfs_header_level(eb) == 0)
500 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
501 else
502 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
503 btrfs_tree_read_unlock(eb);
504 free_extent_buffer(eb);
505 }
506 return 0;
507 }
508
509 /*
510 * merge two lists of backrefs and adjust counts accordingly
511 *
512 * mode = 1: merge identical keys, if key is set
513 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
514 * additionally, we could even add a key range for the blocks we
515 * looked into to merge even more (-> replace unresolved refs by those
516 * having a parent).
517 * mode = 2: merge identical parents
518 */
519 static void __merge_refs(struct list_head *head, int mode)
520 {
521 struct list_head *pos1;
522
523 list_for_each(pos1, head) {
524 struct list_head *n2;
525 struct list_head *pos2;
526 struct __prelim_ref *ref1;
527
528 ref1 = list_entry(pos1, struct __prelim_ref, list);
529
530 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
531 pos2 = n2, n2 = pos2->next) {
532 struct __prelim_ref *ref2;
533 struct __prelim_ref *xchg;
534 struct extent_inode_elem *eie;
535
536 ref2 = list_entry(pos2, struct __prelim_ref, list);
537
538 if (mode == 1) {
539 if (!ref_for_same_block(ref1, ref2))
540 continue;
541 if (!ref1->parent && ref2->parent) {
542 xchg = ref1;
543 ref1 = ref2;
544 ref2 = xchg;
545 }
546 } else {
547 if (ref1->parent != ref2->parent)
548 continue;
549 }
550
551 eie = ref1->inode_list;
552 while (eie && eie->next)
553 eie = eie->next;
554 if (eie)
555 eie->next = ref2->inode_list;
556 else
557 ref1->inode_list = ref2->inode_list;
558 ref1->count += ref2->count;
559
560 list_del(&ref2->list);
561 kmem_cache_free(btrfs_prelim_ref_cache, ref2);
562 }
563
564 }
565 }
566
567 /*
568 * add all currently queued delayed refs from this head whose seq nr is
569 * smaller or equal that seq to the list
570 */
571 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
572 struct list_head *prefs, u64 *total_refs,
573 u64 inum)
574 {
575 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
576 struct rb_node *n = &head->node.rb_node;
577 struct btrfs_key key;
578 struct btrfs_key op_key = {0};
579 int sgn;
580 int ret = 0;
581
582 if (extent_op && extent_op->update_key)
583 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
584
585 spin_lock(&head->lock);
586 n = rb_first(&head->ref_root);
587 while (n) {
588 struct btrfs_delayed_ref_node *node;
589 node = rb_entry(n, struct btrfs_delayed_ref_node,
590 rb_node);
591 n = rb_next(n);
592 if (node->seq > seq)
593 continue;
594
595 switch (node->action) {
596 case BTRFS_ADD_DELAYED_EXTENT:
597 case BTRFS_UPDATE_DELAYED_HEAD:
598 WARN_ON(1);
599 continue;
600 case BTRFS_ADD_DELAYED_REF:
601 sgn = 1;
602 break;
603 case BTRFS_DROP_DELAYED_REF:
604 sgn = -1;
605 break;
606 default:
607 BUG_ON(1);
608 }
609 *total_refs += (node->ref_mod * sgn);
610 switch (node->type) {
611 case BTRFS_TREE_BLOCK_REF_KEY: {
612 struct btrfs_delayed_tree_ref *ref;
613
614 ref = btrfs_delayed_node_to_tree_ref(node);
615 ret = __add_prelim_ref(prefs, ref->root, &op_key,
616 ref->level + 1, 0, node->bytenr,
617 node->ref_mod * sgn, GFP_ATOMIC);
618 break;
619 }
620 case BTRFS_SHARED_BLOCK_REF_KEY: {
621 struct btrfs_delayed_tree_ref *ref;
622
623 ref = btrfs_delayed_node_to_tree_ref(node);
624 ret = __add_prelim_ref(prefs, ref->root, NULL,
625 ref->level + 1, ref->parent,
626 node->bytenr,
627 node->ref_mod * sgn, GFP_ATOMIC);
628 break;
629 }
630 case BTRFS_EXTENT_DATA_REF_KEY: {
631 struct btrfs_delayed_data_ref *ref;
632 ref = btrfs_delayed_node_to_data_ref(node);
633
634 key.objectid = ref->objectid;
635 key.type = BTRFS_EXTENT_DATA_KEY;
636 key.offset = ref->offset;
637
638 /*
639 * Found a inum that doesn't match our known inum, we
640 * know it's shared.
641 */
642 if (inum && ref->objectid != inum) {
643 ret = BACKREF_FOUND_SHARED;
644 break;
645 }
646
647 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
648 node->bytenr,
649 node->ref_mod * sgn, GFP_ATOMIC);
650 break;
651 }
652 case BTRFS_SHARED_DATA_REF_KEY: {
653 struct btrfs_delayed_data_ref *ref;
654
655 ref = btrfs_delayed_node_to_data_ref(node);
656
657 key.objectid = ref->objectid;
658 key.type = BTRFS_EXTENT_DATA_KEY;
659 key.offset = ref->offset;
660 ret = __add_prelim_ref(prefs, ref->root, &key, 0,
661 ref->parent, node->bytenr,
662 node->ref_mod * sgn, GFP_ATOMIC);
663 break;
664 }
665 default:
666 WARN_ON(1);
667 }
668 if (ret)
669 break;
670 }
671 spin_unlock(&head->lock);
672 return ret;
673 }
674
675 /*
676 * add all inline backrefs for bytenr to the list
677 */
678 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
679 struct btrfs_path *path, u64 bytenr,
680 int *info_level, struct list_head *prefs,
681 u64 *total_refs, u64 inum)
682 {
683 int ret = 0;
684 int slot;
685 struct extent_buffer *leaf;
686 struct btrfs_key key;
687 struct btrfs_key found_key;
688 unsigned long ptr;
689 unsigned long end;
690 struct btrfs_extent_item *ei;
691 u64 flags;
692 u64 item_size;
693
694 /*
695 * enumerate all inline refs
696 */
697 leaf = path->nodes[0];
698 slot = path->slots[0];
699
700 item_size = btrfs_item_size_nr(leaf, slot);
701 BUG_ON(item_size < sizeof(*ei));
702
703 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
704 flags = btrfs_extent_flags(leaf, ei);
705 *total_refs += btrfs_extent_refs(leaf, ei);
706 btrfs_item_key_to_cpu(leaf, &found_key, slot);
707
708 ptr = (unsigned long)(ei + 1);
709 end = (unsigned long)ei + item_size;
710
711 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
712 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
713 struct btrfs_tree_block_info *info;
714
715 info = (struct btrfs_tree_block_info *)ptr;
716 *info_level = btrfs_tree_block_level(leaf, info);
717 ptr += sizeof(struct btrfs_tree_block_info);
718 BUG_ON(ptr > end);
719 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
720 *info_level = found_key.offset;
721 } else {
722 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
723 }
724
725 while (ptr < end) {
726 struct btrfs_extent_inline_ref *iref;
727 u64 offset;
728 int type;
729
730 iref = (struct btrfs_extent_inline_ref *)ptr;
731 type = btrfs_extent_inline_ref_type(leaf, iref);
732 offset = btrfs_extent_inline_ref_offset(leaf, iref);
733
734 switch (type) {
735 case BTRFS_SHARED_BLOCK_REF_KEY:
736 ret = __add_prelim_ref(prefs, 0, NULL,
737 *info_level + 1, offset,
738 bytenr, 1, GFP_NOFS);
739 break;
740 case BTRFS_SHARED_DATA_REF_KEY: {
741 struct btrfs_shared_data_ref *sdref;
742 int count;
743
744 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
745 count = btrfs_shared_data_ref_count(leaf, sdref);
746 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
747 bytenr, count, GFP_NOFS);
748 break;
749 }
750 case BTRFS_TREE_BLOCK_REF_KEY:
751 ret = __add_prelim_ref(prefs, offset, NULL,
752 *info_level + 1, 0,
753 bytenr, 1, GFP_NOFS);
754 break;
755 case BTRFS_EXTENT_DATA_REF_KEY: {
756 struct btrfs_extent_data_ref *dref;
757 int count;
758 u64 root;
759
760 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
761 count = btrfs_extent_data_ref_count(leaf, dref);
762 key.objectid = btrfs_extent_data_ref_objectid(leaf,
763 dref);
764 key.type = BTRFS_EXTENT_DATA_KEY;
765 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
766
767 if (inum && key.objectid != inum) {
768 ret = BACKREF_FOUND_SHARED;
769 break;
770 }
771
772 root = btrfs_extent_data_ref_root(leaf, dref);
773 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
774 bytenr, count, GFP_NOFS);
775 break;
776 }
777 default:
778 WARN_ON(1);
779 }
780 if (ret)
781 return ret;
782 ptr += btrfs_extent_inline_ref_size(type);
783 }
784
785 return 0;
786 }
787
788 /*
789 * add all non-inline backrefs for bytenr to the list
790 */
791 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
792 struct btrfs_path *path, u64 bytenr,
793 int info_level, struct list_head *prefs, u64 inum)
794 {
795 struct btrfs_root *extent_root = fs_info->extent_root;
796 int ret;
797 int slot;
798 struct extent_buffer *leaf;
799 struct btrfs_key key;
800
801 while (1) {
802 ret = btrfs_next_item(extent_root, path);
803 if (ret < 0)
804 break;
805 if (ret) {
806 ret = 0;
807 break;
808 }
809
810 slot = path->slots[0];
811 leaf = path->nodes[0];
812 btrfs_item_key_to_cpu(leaf, &key, slot);
813
814 if (key.objectid != bytenr)
815 break;
816 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
817 continue;
818 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
819 break;
820
821 switch (key.type) {
822 case BTRFS_SHARED_BLOCK_REF_KEY:
823 ret = __add_prelim_ref(prefs, 0, NULL,
824 info_level + 1, key.offset,
825 bytenr, 1, GFP_NOFS);
826 break;
827 case BTRFS_SHARED_DATA_REF_KEY: {
828 struct btrfs_shared_data_ref *sdref;
829 int count;
830
831 sdref = btrfs_item_ptr(leaf, slot,
832 struct btrfs_shared_data_ref);
833 count = btrfs_shared_data_ref_count(leaf, sdref);
834 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
835 bytenr, count, GFP_NOFS);
836 break;
837 }
838 case BTRFS_TREE_BLOCK_REF_KEY:
839 ret = __add_prelim_ref(prefs, key.offset, NULL,
840 info_level + 1, 0,
841 bytenr, 1, GFP_NOFS);
842 break;
843 case BTRFS_EXTENT_DATA_REF_KEY: {
844 struct btrfs_extent_data_ref *dref;
845 int count;
846 u64 root;
847
848 dref = btrfs_item_ptr(leaf, slot,
849 struct btrfs_extent_data_ref);
850 count = btrfs_extent_data_ref_count(leaf, dref);
851 key.objectid = btrfs_extent_data_ref_objectid(leaf,
852 dref);
853 key.type = BTRFS_EXTENT_DATA_KEY;
854 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
855
856 if (inum && key.objectid != inum) {
857 ret = BACKREF_FOUND_SHARED;
858 break;
859 }
860
861 root = btrfs_extent_data_ref_root(leaf, dref);
862 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
863 bytenr, count, GFP_NOFS);
864 break;
865 }
866 default:
867 WARN_ON(1);
868 }
869 if (ret)
870 return ret;
871
872 }
873
874 return ret;
875 }
876
877 /*
878 * this adds all existing backrefs (inline backrefs, backrefs and delayed
879 * refs) for the given bytenr to the refs list, merges duplicates and resolves
880 * indirect refs to their parent bytenr.
881 * When roots are found, they're added to the roots list
882 *
883 * NOTE: This can return values > 0
884 *
885 * FIXME some caching might speed things up
886 */
887 static int find_parent_nodes(struct btrfs_trans_handle *trans,
888 struct btrfs_fs_info *fs_info, u64 bytenr,
889 u64 time_seq, struct ulist *refs,
890 struct ulist *roots, const u64 *extent_item_pos,
891 u64 root_objectid, u64 inum)
892 {
893 struct btrfs_key key;
894 struct btrfs_path *path;
895 struct btrfs_delayed_ref_root *delayed_refs = NULL;
896 struct btrfs_delayed_ref_head *head;
897 int info_level = 0;
898 int ret;
899 struct list_head prefs_delayed;
900 struct list_head prefs;
901 struct __prelim_ref *ref;
902 struct extent_inode_elem *eie = NULL;
903 u64 total_refs = 0;
904
905 INIT_LIST_HEAD(&prefs);
906 INIT_LIST_HEAD(&prefs_delayed);
907
908 key.objectid = bytenr;
909 key.offset = (u64)-1;
910 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
911 key.type = BTRFS_METADATA_ITEM_KEY;
912 else
913 key.type = BTRFS_EXTENT_ITEM_KEY;
914
915 path = btrfs_alloc_path();
916 if (!path)
917 return -ENOMEM;
918 if (!trans) {
919 path->search_commit_root = 1;
920 path->skip_locking = 1;
921 }
922
923 /*
924 * grab both a lock on the path and a lock on the delayed ref head.
925 * We need both to get a consistent picture of how the refs look
926 * at a specified point in time
927 */
928 again:
929 head = NULL;
930
931 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
932 if (ret < 0)
933 goto out;
934 BUG_ON(ret == 0);
935
936 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
937 if (trans && likely(trans->type != __TRANS_DUMMY)) {
938 #else
939 if (trans) {
940 #endif
941 /*
942 * look if there are updates for this ref queued and lock the
943 * head
944 */
945 delayed_refs = &trans->transaction->delayed_refs;
946 spin_lock(&delayed_refs->lock);
947 head = btrfs_find_delayed_ref_head(trans, bytenr);
948 if (head) {
949 if (!mutex_trylock(&head->mutex)) {
950 atomic_inc(&head->node.refs);
951 spin_unlock(&delayed_refs->lock);
952
953 btrfs_release_path(path);
954
955 /*
956 * Mutex was contended, block until it's
957 * released and try again
958 */
959 mutex_lock(&head->mutex);
960 mutex_unlock(&head->mutex);
961 btrfs_put_delayed_ref(&head->node);
962 goto again;
963 }
964 spin_unlock(&delayed_refs->lock);
965 ret = __add_delayed_refs(head, time_seq,
966 &prefs_delayed, &total_refs,
967 inum);
968 mutex_unlock(&head->mutex);
969 if (ret)
970 goto out;
971 } else {
972 spin_unlock(&delayed_refs->lock);
973 }
974 }
975
976 if (path->slots[0]) {
977 struct extent_buffer *leaf;
978 int slot;
979
980 path->slots[0]--;
981 leaf = path->nodes[0];
982 slot = path->slots[0];
983 btrfs_item_key_to_cpu(leaf, &key, slot);
984 if (key.objectid == bytenr &&
985 (key.type == BTRFS_EXTENT_ITEM_KEY ||
986 key.type == BTRFS_METADATA_ITEM_KEY)) {
987 ret = __add_inline_refs(fs_info, path, bytenr,
988 &info_level, &prefs,
989 &total_refs, inum);
990 if (ret)
991 goto out;
992 ret = __add_keyed_refs(fs_info, path, bytenr,
993 info_level, &prefs, inum);
994 if (ret)
995 goto out;
996 }
997 }
998 btrfs_release_path(path);
999
1000 list_splice_init(&prefs_delayed, &prefs);
1001
1002 ret = __add_missing_keys(fs_info, &prefs);
1003 if (ret)
1004 goto out;
1005
1006 __merge_refs(&prefs, 1);
1007
1008 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
1009 extent_item_pos, total_refs,
1010 root_objectid);
1011 if (ret)
1012 goto out;
1013
1014 __merge_refs(&prefs, 2);
1015
1016 while (!list_empty(&prefs)) {
1017 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1018 WARN_ON(ref->count < 0);
1019 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1020 if (root_objectid && ref->root_id != root_objectid) {
1021 ret = BACKREF_FOUND_SHARED;
1022 goto out;
1023 }
1024
1025 /* no parent == root of tree */
1026 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1027 if (ret < 0)
1028 goto out;
1029 }
1030 if (ref->count && ref->parent) {
1031 if (extent_item_pos && !ref->inode_list &&
1032 ref->level == 0) {
1033 struct extent_buffer *eb;
1034
1035 eb = read_tree_block(fs_info->extent_root,
1036 ref->parent, 0);
1037 if (!eb || !extent_buffer_uptodate(eb)) {
1038 free_extent_buffer(eb);
1039 ret = -EIO;
1040 goto out;
1041 }
1042 btrfs_tree_read_lock(eb);
1043 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1044 ret = find_extent_in_eb(eb, bytenr,
1045 *extent_item_pos, &eie);
1046 btrfs_tree_read_unlock_blocking(eb);
1047 free_extent_buffer(eb);
1048 if (ret < 0)
1049 goto out;
1050 ref->inode_list = eie;
1051 }
1052 ret = ulist_add_merge_ptr(refs, ref->parent,
1053 ref->inode_list,
1054 (void **)&eie, GFP_NOFS);
1055 if (ret < 0)
1056 goto out;
1057 if (!ret && extent_item_pos) {
1058 /*
1059 * we've recorded that parent, so we must extend
1060 * its inode list here
1061 */
1062 BUG_ON(!eie);
1063 while (eie->next)
1064 eie = eie->next;
1065 eie->next = ref->inode_list;
1066 }
1067 eie = NULL;
1068 }
1069 list_del(&ref->list);
1070 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1071 }
1072
1073 out:
1074 btrfs_free_path(path);
1075 while (!list_empty(&prefs)) {
1076 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1077 list_del(&ref->list);
1078 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1079 }
1080 while (!list_empty(&prefs_delayed)) {
1081 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
1082 list);
1083 list_del(&ref->list);
1084 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1085 }
1086 if (ret < 0)
1087 free_inode_elem_list(eie);
1088 return ret;
1089 }
1090
1091 static void free_leaf_list(struct ulist *blocks)
1092 {
1093 struct ulist_node *node = NULL;
1094 struct extent_inode_elem *eie;
1095 struct ulist_iterator uiter;
1096
1097 ULIST_ITER_INIT(&uiter);
1098 while ((node = ulist_next(blocks, &uiter))) {
1099 if (!node->aux)
1100 continue;
1101 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1102 free_inode_elem_list(eie);
1103 node->aux = 0;
1104 }
1105
1106 ulist_free(blocks);
1107 }
1108
1109 /*
1110 * Finds all leafs with a reference to the specified combination of bytenr and
1111 * offset. key_list_head will point to a list of corresponding keys (caller must
1112 * free each list element). The leafs will be stored in the leafs ulist, which
1113 * must be freed with ulist_free.
1114 *
1115 * returns 0 on success, <0 on error
1116 */
1117 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1118 struct btrfs_fs_info *fs_info, u64 bytenr,
1119 u64 time_seq, struct ulist **leafs,
1120 const u64 *extent_item_pos)
1121 {
1122 int ret;
1123
1124 *leafs = ulist_alloc(GFP_NOFS);
1125 if (!*leafs)
1126 return -ENOMEM;
1127
1128 ret = find_parent_nodes(trans, fs_info, bytenr,
1129 time_seq, *leafs, NULL, extent_item_pos, 0, 0);
1130 if (ret < 0 && ret != -ENOENT) {
1131 free_leaf_list(*leafs);
1132 return ret;
1133 }
1134
1135 return 0;
1136 }
1137
1138 /*
1139 * walk all backrefs for a given extent to find all roots that reference this
1140 * extent. Walking a backref means finding all extents that reference this
1141 * extent and in turn walk the backrefs of those, too. Naturally this is a
1142 * recursive process, but here it is implemented in an iterative fashion: We
1143 * find all referencing extents for the extent in question and put them on a
1144 * list. In turn, we find all referencing extents for those, further appending
1145 * to the list. The way we iterate the list allows adding more elements after
1146 * the current while iterating. The process stops when we reach the end of the
1147 * list. Found roots are added to the roots list.
1148 *
1149 * returns 0 on success, < 0 on error.
1150 */
1151 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1152 struct btrfs_fs_info *fs_info, u64 bytenr,
1153 u64 time_seq, struct ulist **roots)
1154 {
1155 struct ulist *tmp;
1156 struct ulist_node *node = NULL;
1157 struct ulist_iterator uiter;
1158 int ret;
1159
1160 tmp = ulist_alloc(GFP_NOFS);
1161 if (!tmp)
1162 return -ENOMEM;
1163 *roots = ulist_alloc(GFP_NOFS);
1164 if (!*roots) {
1165 ulist_free(tmp);
1166 return -ENOMEM;
1167 }
1168
1169 ULIST_ITER_INIT(&uiter);
1170 while (1) {
1171 ret = find_parent_nodes(trans, fs_info, bytenr,
1172 time_seq, tmp, *roots, NULL, 0, 0);
1173 if (ret < 0 && ret != -ENOENT) {
1174 ulist_free(tmp);
1175 ulist_free(*roots);
1176 return ret;
1177 }
1178 node = ulist_next(tmp, &uiter);
1179 if (!node)
1180 break;
1181 bytenr = node->val;
1182 cond_resched();
1183 }
1184
1185 ulist_free(tmp);
1186 return 0;
1187 }
1188
1189 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1190 struct btrfs_fs_info *fs_info, u64 bytenr,
1191 u64 time_seq, struct ulist **roots)
1192 {
1193 int ret;
1194
1195 if (!trans)
1196 down_read(&fs_info->commit_root_sem);
1197 ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
1198 if (!trans)
1199 up_read(&fs_info->commit_root_sem);
1200 return ret;
1201 }
1202
1203 /**
1204 * btrfs_check_shared - tell us whether an extent is shared
1205 *
1206 * @trans: optional trans handle
1207 *
1208 * btrfs_check_shared uses the backref walking code but will short
1209 * circuit as soon as it finds a root or inode that doesn't match the
1210 * one passed in. This provides a significant performance benefit for
1211 * callers (such as fiemap) which want to know whether the extent is
1212 * shared but do not need a ref count.
1213 *
1214 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1215 */
1216 int btrfs_check_shared(struct btrfs_trans_handle *trans,
1217 struct btrfs_fs_info *fs_info, u64 root_objectid,
1218 u64 inum, u64 bytenr)
1219 {
1220 struct ulist *tmp = NULL;
1221 struct ulist *roots = NULL;
1222 struct ulist_iterator uiter;
1223 struct ulist_node *node;
1224 struct seq_list elem = SEQ_LIST_INIT(elem);
1225 int ret = 0;
1226
1227 tmp = ulist_alloc(GFP_NOFS);
1228 roots = ulist_alloc(GFP_NOFS);
1229 if (!tmp || !roots) {
1230 ulist_free(tmp);
1231 ulist_free(roots);
1232 return -ENOMEM;
1233 }
1234
1235 if (trans)
1236 btrfs_get_tree_mod_seq(fs_info, &elem);
1237 else
1238 down_read(&fs_info->commit_root_sem);
1239 ULIST_ITER_INIT(&uiter);
1240 while (1) {
1241 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1242 roots, NULL, root_objectid, inum);
1243 if (ret == BACKREF_FOUND_SHARED) {
1244 /* this is the only condition under which we return 1 */
1245 ret = 1;
1246 break;
1247 }
1248 if (ret < 0 && ret != -ENOENT)
1249 break;
1250 ret = 0;
1251 node = ulist_next(tmp, &uiter);
1252 if (!node)
1253 break;
1254 bytenr = node->val;
1255 cond_resched();
1256 }
1257 if (trans)
1258 btrfs_put_tree_mod_seq(fs_info, &elem);
1259 else
1260 up_read(&fs_info->commit_root_sem);
1261 ulist_free(tmp);
1262 ulist_free(roots);
1263 return ret;
1264 }
1265
1266 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1267 u64 start_off, struct btrfs_path *path,
1268 struct btrfs_inode_extref **ret_extref,
1269 u64 *found_off)
1270 {
1271 int ret, slot;
1272 struct btrfs_key key;
1273 struct btrfs_key found_key;
1274 struct btrfs_inode_extref *extref;
1275 struct extent_buffer *leaf;
1276 unsigned long ptr;
1277
1278 key.objectid = inode_objectid;
1279 key.type = BTRFS_INODE_EXTREF_KEY;
1280 key.offset = start_off;
1281
1282 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1283 if (ret < 0)
1284 return ret;
1285
1286 while (1) {
1287 leaf = path->nodes[0];
1288 slot = path->slots[0];
1289 if (slot >= btrfs_header_nritems(leaf)) {
1290 /*
1291 * If the item at offset is not found,
1292 * btrfs_search_slot will point us to the slot
1293 * where it should be inserted. In our case
1294 * that will be the slot directly before the
1295 * next INODE_REF_KEY_V2 item. In the case
1296 * that we're pointing to the last slot in a
1297 * leaf, we must move one leaf over.
1298 */
1299 ret = btrfs_next_leaf(root, path);
1300 if (ret) {
1301 if (ret >= 1)
1302 ret = -ENOENT;
1303 break;
1304 }
1305 continue;
1306 }
1307
1308 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1309
1310 /*
1311 * Check that we're still looking at an extended ref key for
1312 * this particular objectid. If we have different
1313 * objectid or type then there are no more to be found
1314 * in the tree and we can exit.
1315 */
1316 ret = -ENOENT;
1317 if (found_key.objectid != inode_objectid)
1318 break;
1319 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1320 break;
1321
1322 ret = 0;
1323 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1324 extref = (struct btrfs_inode_extref *)ptr;
1325 *ret_extref = extref;
1326 if (found_off)
1327 *found_off = found_key.offset;
1328 break;
1329 }
1330
1331 return ret;
1332 }
1333
1334 /*
1335 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1336 * Elements of the path are separated by '/' and the path is guaranteed to be
1337 * 0-terminated. the path is only given within the current file system.
1338 * Therefore, it never starts with a '/'. the caller is responsible to provide
1339 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1340 * the start point of the resulting string is returned. this pointer is within
1341 * dest, normally.
1342 * in case the path buffer would overflow, the pointer is decremented further
1343 * as if output was written to the buffer, though no more output is actually
1344 * generated. that way, the caller can determine how much space would be
1345 * required for the path to fit into the buffer. in that case, the returned
1346 * value will be smaller than dest. callers must check this!
1347 */
1348 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1349 u32 name_len, unsigned long name_off,
1350 struct extent_buffer *eb_in, u64 parent,
1351 char *dest, u32 size)
1352 {
1353 int slot;
1354 u64 next_inum;
1355 int ret;
1356 s64 bytes_left = ((s64)size) - 1;
1357 struct extent_buffer *eb = eb_in;
1358 struct btrfs_key found_key;
1359 int leave_spinning = path->leave_spinning;
1360 struct btrfs_inode_ref *iref;
1361
1362 if (bytes_left >= 0)
1363 dest[bytes_left] = '\0';
1364
1365 path->leave_spinning = 1;
1366 while (1) {
1367 bytes_left -= name_len;
1368 if (bytes_left >= 0)
1369 read_extent_buffer(eb, dest + bytes_left,
1370 name_off, name_len);
1371 if (eb != eb_in) {
1372 btrfs_tree_read_unlock_blocking(eb);
1373 free_extent_buffer(eb);
1374 }
1375 ret = btrfs_find_item(fs_root, path, parent, 0,
1376 BTRFS_INODE_REF_KEY, &found_key);
1377 if (ret > 0)
1378 ret = -ENOENT;
1379 if (ret)
1380 break;
1381
1382 next_inum = found_key.offset;
1383
1384 /* regular exit ahead */
1385 if (parent == next_inum)
1386 break;
1387
1388 slot = path->slots[0];
1389 eb = path->nodes[0];
1390 /* make sure we can use eb after releasing the path */
1391 if (eb != eb_in) {
1392 atomic_inc(&eb->refs);
1393 btrfs_tree_read_lock(eb);
1394 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1395 }
1396 btrfs_release_path(path);
1397 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1398
1399 name_len = btrfs_inode_ref_name_len(eb, iref);
1400 name_off = (unsigned long)(iref + 1);
1401
1402 parent = next_inum;
1403 --bytes_left;
1404 if (bytes_left >= 0)
1405 dest[bytes_left] = '/';
1406 }
1407
1408 btrfs_release_path(path);
1409 path->leave_spinning = leave_spinning;
1410
1411 if (ret)
1412 return ERR_PTR(ret);
1413
1414 return dest + bytes_left;
1415 }
1416
1417 /*
1418 * this makes the path point to (logical EXTENT_ITEM *)
1419 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1420 * tree blocks and <0 on error.
1421 */
1422 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1423 struct btrfs_path *path, struct btrfs_key *found_key,
1424 u64 *flags_ret)
1425 {
1426 int ret;
1427 u64 flags;
1428 u64 size = 0;
1429 u32 item_size;
1430 struct extent_buffer *eb;
1431 struct btrfs_extent_item *ei;
1432 struct btrfs_key key;
1433
1434 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1435 key.type = BTRFS_METADATA_ITEM_KEY;
1436 else
1437 key.type = BTRFS_EXTENT_ITEM_KEY;
1438 key.objectid = logical;
1439 key.offset = (u64)-1;
1440
1441 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1442 if (ret < 0)
1443 return ret;
1444
1445 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1446 if (ret) {
1447 if (ret > 0)
1448 ret = -ENOENT;
1449 return ret;
1450 }
1451 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1452 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1453 size = fs_info->extent_root->nodesize;
1454 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1455 size = found_key->offset;
1456
1457 if (found_key->objectid > logical ||
1458 found_key->objectid + size <= logical) {
1459 pr_debug("logical %llu is not within any extent\n", logical);
1460 return -ENOENT;
1461 }
1462
1463 eb = path->nodes[0];
1464 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1465 BUG_ON(item_size < sizeof(*ei));
1466
1467 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1468 flags = btrfs_extent_flags(eb, ei);
1469
1470 pr_debug("logical %llu is at position %llu within the extent (%llu "
1471 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1472 logical, logical - found_key->objectid, found_key->objectid,
1473 found_key->offset, flags, item_size);
1474
1475 WARN_ON(!flags_ret);
1476 if (flags_ret) {
1477 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1478 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1479 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1480 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1481 else
1482 BUG_ON(1);
1483 return 0;
1484 }
1485
1486 return -EIO;
1487 }
1488
1489 /*
1490 * helper function to iterate extent inline refs. ptr must point to a 0 value
1491 * for the first call and may be modified. it is used to track state.
1492 * if more refs exist, 0 is returned and the next call to
1493 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1494 * next ref. after the last ref was processed, 1 is returned.
1495 * returns <0 on error
1496 */
1497 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1498 struct btrfs_key *key,
1499 struct btrfs_extent_item *ei, u32 item_size,
1500 struct btrfs_extent_inline_ref **out_eiref,
1501 int *out_type)
1502 {
1503 unsigned long end;
1504 u64 flags;
1505 struct btrfs_tree_block_info *info;
1506
1507 if (!*ptr) {
1508 /* first call */
1509 flags = btrfs_extent_flags(eb, ei);
1510 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1511 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1512 /* a skinny metadata extent */
1513 *out_eiref =
1514 (struct btrfs_extent_inline_ref *)(ei + 1);
1515 } else {
1516 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1517 info = (struct btrfs_tree_block_info *)(ei + 1);
1518 *out_eiref =
1519 (struct btrfs_extent_inline_ref *)(info + 1);
1520 }
1521 } else {
1522 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1523 }
1524 *ptr = (unsigned long)*out_eiref;
1525 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1526 return -ENOENT;
1527 }
1528
1529 end = (unsigned long)ei + item_size;
1530 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1531 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1532
1533 *ptr += btrfs_extent_inline_ref_size(*out_type);
1534 WARN_ON(*ptr > end);
1535 if (*ptr == end)
1536 return 1; /* last */
1537
1538 return 0;
1539 }
1540
1541 /*
1542 * reads the tree block backref for an extent. tree level and root are returned
1543 * through out_level and out_root. ptr must point to a 0 value for the first
1544 * call and may be modified (see __get_extent_inline_ref comment).
1545 * returns 0 if data was provided, 1 if there was no more data to provide or
1546 * <0 on error.
1547 */
1548 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1549 struct btrfs_key *key, struct btrfs_extent_item *ei,
1550 u32 item_size, u64 *out_root, u8 *out_level)
1551 {
1552 int ret;
1553 int type;
1554 struct btrfs_extent_inline_ref *eiref;
1555
1556 if (*ptr == (unsigned long)-1)
1557 return 1;
1558
1559 while (1) {
1560 ret = __get_extent_inline_ref(ptr, eb, key, ei, item_size,
1561 &eiref, &type);
1562 if (ret < 0)
1563 return ret;
1564
1565 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1566 type == BTRFS_SHARED_BLOCK_REF_KEY)
1567 break;
1568
1569 if (ret == 1)
1570 return 1;
1571 }
1572
1573 /* we can treat both ref types equally here */
1574 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1575
1576 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1577 struct btrfs_tree_block_info *info;
1578
1579 info = (struct btrfs_tree_block_info *)(ei + 1);
1580 *out_level = btrfs_tree_block_level(eb, info);
1581 } else {
1582 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1583 *out_level = (u8)key->offset;
1584 }
1585
1586 if (ret == 1)
1587 *ptr = (unsigned long)-1;
1588
1589 return 0;
1590 }
1591
1592 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1593 u64 root, u64 extent_item_objectid,
1594 iterate_extent_inodes_t *iterate, void *ctx)
1595 {
1596 struct extent_inode_elem *eie;
1597 int ret = 0;
1598
1599 for (eie = inode_list; eie; eie = eie->next) {
1600 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1601 "root %llu\n", extent_item_objectid,
1602 eie->inum, eie->offset, root);
1603 ret = iterate(eie->inum, eie->offset, root, ctx);
1604 if (ret) {
1605 pr_debug("stopping iteration for %llu due to ret=%d\n",
1606 extent_item_objectid, ret);
1607 break;
1608 }
1609 }
1610
1611 return ret;
1612 }
1613
1614 /*
1615 * calls iterate() for every inode that references the extent identified by
1616 * the given parameters.
1617 * when the iterator function returns a non-zero value, iteration stops.
1618 */
1619 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1620 u64 extent_item_objectid, u64 extent_item_pos,
1621 int search_commit_root,
1622 iterate_extent_inodes_t *iterate, void *ctx)
1623 {
1624 int ret;
1625 struct btrfs_trans_handle *trans = NULL;
1626 struct ulist *refs = NULL;
1627 struct ulist *roots = NULL;
1628 struct ulist_node *ref_node = NULL;
1629 struct ulist_node *root_node = NULL;
1630 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
1631 struct ulist_iterator ref_uiter;
1632 struct ulist_iterator root_uiter;
1633
1634 pr_debug("resolving all inodes for extent %llu\n",
1635 extent_item_objectid);
1636
1637 if (!search_commit_root) {
1638 trans = btrfs_join_transaction(fs_info->extent_root);
1639 if (IS_ERR(trans))
1640 return PTR_ERR(trans);
1641 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1642 } else {
1643 down_read(&fs_info->commit_root_sem);
1644 }
1645
1646 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1647 tree_mod_seq_elem.seq, &refs,
1648 &extent_item_pos);
1649 if (ret)
1650 goto out;
1651
1652 ULIST_ITER_INIT(&ref_uiter);
1653 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1654 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
1655 tree_mod_seq_elem.seq, &roots);
1656 if (ret)
1657 break;
1658 ULIST_ITER_INIT(&root_uiter);
1659 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1660 pr_debug("root %llu references leaf %llu, data list "
1661 "%#llx\n", root_node->val, ref_node->val,
1662 ref_node->aux);
1663 ret = iterate_leaf_refs((struct extent_inode_elem *)
1664 (uintptr_t)ref_node->aux,
1665 root_node->val,
1666 extent_item_objectid,
1667 iterate, ctx);
1668 }
1669 ulist_free(roots);
1670 }
1671
1672 free_leaf_list(refs);
1673 out:
1674 if (!search_commit_root) {
1675 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1676 btrfs_end_transaction(trans, fs_info->extent_root);
1677 } else {
1678 up_read(&fs_info->commit_root_sem);
1679 }
1680
1681 return ret;
1682 }
1683
1684 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1685 struct btrfs_path *path,
1686 iterate_extent_inodes_t *iterate, void *ctx)
1687 {
1688 int ret;
1689 u64 extent_item_pos;
1690 u64 flags = 0;
1691 struct btrfs_key found_key;
1692 int search_commit_root = path->search_commit_root;
1693
1694 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1695 btrfs_release_path(path);
1696 if (ret < 0)
1697 return ret;
1698 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1699 return -EINVAL;
1700
1701 extent_item_pos = logical - found_key.objectid;
1702 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1703 extent_item_pos, search_commit_root,
1704 iterate, ctx);
1705
1706 return ret;
1707 }
1708
1709 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1710 struct extent_buffer *eb, void *ctx);
1711
1712 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1713 struct btrfs_path *path,
1714 iterate_irefs_t *iterate, void *ctx)
1715 {
1716 int ret = 0;
1717 int slot;
1718 u32 cur;
1719 u32 len;
1720 u32 name_len;
1721 u64 parent = 0;
1722 int found = 0;
1723 struct extent_buffer *eb;
1724 struct btrfs_item *item;
1725 struct btrfs_inode_ref *iref;
1726 struct btrfs_key found_key;
1727
1728 while (!ret) {
1729 ret = btrfs_find_item(fs_root, path, inum,
1730 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
1731 &found_key);
1732
1733 if (ret < 0)
1734 break;
1735 if (ret) {
1736 ret = found ? 0 : -ENOENT;
1737 break;
1738 }
1739 ++found;
1740
1741 parent = found_key.offset;
1742 slot = path->slots[0];
1743 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1744 if (!eb) {
1745 ret = -ENOMEM;
1746 break;
1747 }
1748 extent_buffer_get(eb);
1749 btrfs_tree_read_lock(eb);
1750 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1751 btrfs_release_path(path);
1752
1753 item = btrfs_item_nr(slot);
1754 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1755
1756 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1757 name_len = btrfs_inode_ref_name_len(eb, iref);
1758 /* path must be released before calling iterate()! */
1759 pr_debug("following ref at offset %u for inode %llu in "
1760 "tree %llu\n", cur, found_key.objectid,
1761 fs_root->objectid);
1762 ret = iterate(parent, name_len,
1763 (unsigned long)(iref + 1), eb, ctx);
1764 if (ret)
1765 break;
1766 len = sizeof(*iref) + name_len;
1767 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1768 }
1769 btrfs_tree_read_unlock_blocking(eb);
1770 free_extent_buffer(eb);
1771 }
1772
1773 btrfs_release_path(path);
1774
1775 return ret;
1776 }
1777
1778 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1779 struct btrfs_path *path,
1780 iterate_irefs_t *iterate, void *ctx)
1781 {
1782 int ret;
1783 int slot;
1784 u64 offset = 0;
1785 u64 parent;
1786 int found = 0;
1787 struct extent_buffer *eb;
1788 struct btrfs_inode_extref *extref;
1789 struct extent_buffer *leaf;
1790 u32 item_size;
1791 u32 cur_offset;
1792 unsigned long ptr;
1793
1794 while (1) {
1795 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1796 &offset);
1797 if (ret < 0)
1798 break;
1799 if (ret) {
1800 ret = found ? 0 : -ENOENT;
1801 break;
1802 }
1803 ++found;
1804
1805 slot = path->slots[0];
1806 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1807 if (!eb) {
1808 ret = -ENOMEM;
1809 break;
1810 }
1811 extent_buffer_get(eb);
1812
1813 btrfs_tree_read_lock(eb);
1814 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1815 btrfs_release_path(path);
1816
1817 leaf = path->nodes[0];
1818 item_size = btrfs_item_size_nr(leaf, slot);
1819 ptr = btrfs_item_ptr_offset(leaf, slot);
1820 cur_offset = 0;
1821
1822 while (cur_offset < item_size) {
1823 u32 name_len;
1824
1825 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1826 parent = btrfs_inode_extref_parent(eb, extref);
1827 name_len = btrfs_inode_extref_name_len(eb, extref);
1828 ret = iterate(parent, name_len,
1829 (unsigned long)&extref->name, eb, ctx);
1830 if (ret)
1831 break;
1832
1833 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1834 cur_offset += sizeof(*extref);
1835 }
1836 btrfs_tree_read_unlock_blocking(eb);
1837 free_extent_buffer(eb);
1838
1839 offset++;
1840 }
1841
1842 btrfs_release_path(path);
1843
1844 return ret;
1845 }
1846
1847 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1848 struct btrfs_path *path, iterate_irefs_t *iterate,
1849 void *ctx)
1850 {
1851 int ret;
1852 int found_refs = 0;
1853
1854 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1855 if (!ret)
1856 ++found_refs;
1857 else if (ret != -ENOENT)
1858 return ret;
1859
1860 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1861 if (ret == -ENOENT && found_refs)
1862 return 0;
1863
1864 return ret;
1865 }
1866
1867 /*
1868 * returns 0 if the path could be dumped (probably truncated)
1869 * returns <0 in case of an error
1870 */
1871 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1872 struct extent_buffer *eb, void *ctx)
1873 {
1874 struct inode_fs_paths *ipath = ctx;
1875 char *fspath;
1876 char *fspath_min;
1877 int i = ipath->fspath->elem_cnt;
1878 const int s_ptr = sizeof(char *);
1879 u32 bytes_left;
1880
1881 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1882 ipath->fspath->bytes_left - s_ptr : 0;
1883
1884 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1885 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1886 name_off, eb, inum, fspath_min, bytes_left);
1887 if (IS_ERR(fspath))
1888 return PTR_ERR(fspath);
1889
1890 if (fspath > fspath_min) {
1891 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1892 ++ipath->fspath->elem_cnt;
1893 ipath->fspath->bytes_left = fspath - fspath_min;
1894 } else {
1895 ++ipath->fspath->elem_missed;
1896 ipath->fspath->bytes_missing += fspath_min - fspath;
1897 ipath->fspath->bytes_left = 0;
1898 }
1899
1900 return 0;
1901 }
1902
1903 /*
1904 * this dumps all file system paths to the inode into the ipath struct, provided
1905 * is has been created large enough. each path is zero-terminated and accessed
1906 * from ipath->fspath->val[i].
1907 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1908 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1909 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1910 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1911 * have been needed to return all paths.
1912 */
1913 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1914 {
1915 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1916 inode_to_path, ipath);
1917 }
1918
1919 struct btrfs_data_container *init_data_container(u32 total_bytes)
1920 {
1921 struct btrfs_data_container *data;
1922 size_t alloc_bytes;
1923
1924 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1925 data = vmalloc(alloc_bytes);
1926 if (!data)
1927 return ERR_PTR(-ENOMEM);
1928
1929 if (total_bytes >= sizeof(*data)) {
1930 data->bytes_left = total_bytes - sizeof(*data);
1931 data->bytes_missing = 0;
1932 } else {
1933 data->bytes_missing = sizeof(*data) - total_bytes;
1934 data->bytes_left = 0;
1935 }
1936
1937 data->elem_cnt = 0;
1938 data->elem_missed = 0;
1939
1940 return data;
1941 }
1942
1943 /*
1944 * allocates space to return multiple file system paths for an inode.
1945 * total_bytes to allocate are passed, note that space usable for actual path
1946 * information will be total_bytes - sizeof(struct inode_fs_paths).
1947 * the returned pointer must be freed with free_ipath() in the end.
1948 */
1949 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1950 struct btrfs_path *path)
1951 {
1952 struct inode_fs_paths *ifp;
1953 struct btrfs_data_container *fspath;
1954
1955 fspath = init_data_container(total_bytes);
1956 if (IS_ERR(fspath))
1957 return (void *)fspath;
1958
1959 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1960 if (!ifp) {
1961 kfree(fspath);
1962 return ERR_PTR(-ENOMEM);
1963 }
1964
1965 ifp->btrfs_path = path;
1966 ifp->fspath = fspath;
1967 ifp->fs_root = fs_root;
1968
1969 return ifp;
1970 }
1971
1972 void free_ipath(struct inode_fs_paths *ipath)
1973 {
1974 if (!ipath)
1975 return;
1976 vfree(ipath->fspath);
1977 kfree(ipath);
1978 }
Linux kernel - Deliverables
This page took 0.076987 seconds and 6 git commands to generate.