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