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1 /*
2 * Copyright (C) 2011 STRATO. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/vmalloc.h>
20 #include "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 offset = 0;
40 struct extent_inode_elem *e;
41
42 if (!btrfs_file_extent_compression(eb, fi) &&
43 !btrfs_file_extent_encryption(eb, fi) &&
44 !btrfs_file_extent_other_encoding(eb, fi)) {
45 u64 data_offset;
46 u64 data_len;
47
48 data_offset = btrfs_file_extent_offset(eb, fi);
49 data_len = btrfs_file_extent_num_bytes(eb, fi);
50
51 if (extent_item_pos < data_offset ||
52 extent_item_pos >= data_offset + data_len)
53 return 1;
54 offset = extent_item_pos - data_offset;
55 }
56
57 e = kmalloc(sizeof(*e), GFP_NOFS);
58 if (!e)
59 return -ENOMEM;
60
61 e->next = *eie;
62 e->inum = key->objectid;
63 e->offset = key->offset + offset;
64 *eie = e;
65
66 return 0;
67 }
68
69 static void free_inode_elem_list(struct extent_inode_elem *eie)
70 {
71 struct extent_inode_elem *eie_next;
72
73 for (; eie; eie = eie_next) {
74 eie_next = eie->next;
75 kfree(eie);
76 }
77 }
78
79 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
80 u64 extent_item_pos,
81 struct extent_inode_elem **eie)
82 {
83 u64 disk_byte;
84 struct btrfs_key key;
85 struct btrfs_file_extent_item *fi;
86 int slot;
87 int nritems;
88 int extent_type;
89 int ret;
90
91 /*
92 * from the shared data ref, we only have the leaf but we need
93 * the key. thus, we must look into all items and see that we
94 * find one (some) with a reference to our extent item.
95 */
96 nritems = btrfs_header_nritems(eb);
97 for (slot = 0; slot < nritems; ++slot) {
98 btrfs_item_key_to_cpu(eb, &key, slot);
99 if (key.type != BTRFS_EXTENT_DATA_KEY)
100 continue;
101 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
102 extent_type = btrfs_file_extent_type(eb, fi);
103 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
104 continue;
105 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
106 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
107 if (disk_byte != wanted_disk_byte)
108 continue;
109
110 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
111 if (ret < 0)
112 return ret;
113 }
114
115 return 0;
116 }
117
118 /*
119 * this structure records all encountered refs on the way up to the root
120 */
121 struct __prelim_ref {
122 struct list_head list;
123 u64 root_id;
124 struct btrfs_key key_for_search;
125 int level;
126 int count;
127 struct extent_inode_elem *inode_list;
128 u64 parent;
129 u64 wanted_disk_byte;
130 };
131
132 static struct kmem_cache *btrfs_prelim_ref_cache;
133
134 int __init btrfs_prelim_ref_init(void)
135 {
136 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
137 sizeof(struct __prelim_ref),
138 0,
139 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
140 NULL);
141 if (!btrfs_prelim_ref_cache)
142 return -ENOMEM;
143 return 0;
144 }
145
146 void btrfs_prelim_ref_exit(void)
147 {
148 if (btrfs_prelim_ref_cache)
149 kmem_cache_destroy(btrfs_prelim_ref_cache);
150 }
151
152 /*
153 * the rules for all callers of this function are:
154 * - obtaining the parent is the goal
155 * - if you add a key, you must know that it is a correct key
156 * - if you cannot add the parent or a correct key, then we will look into the
157 * block later to set a correct key
158 *
159 * delayed refs
160 * ============
161 * backref type | shared | indirect | shared | indirect
162 * information | tree | tree | data | data
163 * --------------------+--------+----------+--------+----------
164 * parent logical | y | - | - | -
165 * key to resolve | - | y | y | y
166 * tree block logical | - | - | - | -
167 * root for resolving | y | y | y | y
168 *
169 * - column 1: we've the parent -> done
170 * - column 2, 3, 4: we use the key to find the parent
171 *
172 * on disk refs (inline or keyed)
173 * ==============================
174 * backref type | shared | indirect | shared | indirect
175 * information | tree | tree | data | data
176 * --------------------+--------+----------+--------+----------
177 * parent logical | y | - | y | -
178 * key to resolve | - | - | - | y
179 * tree block logical | y | y | y | y
180 * root for resolving | - | y | y | y
181 *
182 * - column 1, 3: we've the parent -> done
183 * - column 2: we take the first key from the block to find the parent
184 * (see __add_missing_keys)
185 * - column 4: we use the key to find the parent
186 *
187 * additional information that's available but not required to find the parent
188 * block might help in merging entries to gain some speed.
189 */
190
191 static int __add_prelim_ref(struct list_head *head, u64 root_id,
192 struct btrfs_key *key, int level,
193 u64 parent, u64 wanted_disk_byte, int count,
194 gfp_t gfp_mask)
195 {
196 struct __prelim_ref *ref;
197
198 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
199 return 0;
200
201 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
202 if (!ref)
203 return -ENOMEM;
204
205 ref->root_id = root_id;
206 if (key)
207 ref->key_for_search = *key;
208 else
209 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
210
211 ref->inode_list = NULL;
212 ref->level = level;
213 ref->count = count;
214 ref->parent = parent;
215 ref->wanted_disk_byte = wanted_disk_byte;
216 list_add_tail(&ref->list, head);
217
218 return 0;
219 }
220
221 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
222 struct ulist *parents, struct __prelim_ref *ref,
223 int level, u64 time_seq, const u64 *extent_item_pos,
224 u64 total_refs)
225 {
226 int ret = 0;
227 int slot;
228 struct extent_buffer *eb;
229 struct btrfs_key key;
230 struct btrfs_key *key_for_search = &ref->key_for_search;
231 struct btrfs_file_extent_item *fi;
232 struct extent_inode_elem *eie = NULL, *old = NULL;
233 u64 disk_byte;
234 u64 wanted_disk_byte = ref->wanted_disk_byte;
235 u64 count = 0;
236
237 if (level != 0) {
238 eb = path->nodes[level];
239 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
240 if (ret < 0)
241 return ret;
242 return 0;
243 }
244
245 /*
246 * We normally enter this function with the path already pointing to
247 * the first item to check. But sometimes, we may enter it with
248 * slot==nritems. In that case, go to the next leaf before we continue.
249 */
250 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
251 ret = btrfs_next_old_leaf(root, path, time_seq);
252
253 while (!ret && count < total_refs) {
254 eb = path->nodes[0];
255 slot = path->slots[0];
256
257 btrfs_item_key_to_cpu(eb, &key, slot);
258
259 if (key.objectid != key_for_search->objectid ||
260 key.type != BTRFS_EXTENT_DATA_KEY)
261 break;
262
263 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
264 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
265
266 if (disk_byte == wanted_disk_byte) {
267 eie = NULL;
268 old = NULL;
269 count++;
270 if (extent_item_pos) {
271 ret = check_extent_in_eb(&key, eb, fi,
272 *extent_item_pos,
273 &eie);
274 if (ret < 0)
275 break;
276 }
277 if (ret > 0)
278 goto next;
279 ret = ulist_add_merge(parents, eb->start,
280 (uintptr_t)eie,
281 (u64 *)&old, GFP_NOFS);
282 if (ret < 0)
283 break;
284 if (!ret && extent_item_pos) {
285 while (old->next)
286 old = old->next;
287 old->next = eie;
288 }
289 eie = NULL;
290 }
291 next:
292 ret = btrfs_next_old_item(root, path, time_seq);
293 }
294
295 if (ret > 0)
296 ret = 0;
297 else if (ret < 0)
298 free_inode_elem_list(eie);
299 return ret;
300 }
301
302 /*
303 * resolve an indirect backref in the form (root_id, key, level)
304 * to a logical address
305 */
306 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
307 struct btrfs_path *path, u64 time_seq,
308 struct __prelim_ref *ref,
309 struct ulist *parents,
310 const u64 *extent_item_pos, u64 total_refs)
311 {
312 struct btrfs_root *root;
313 struct btrfs_key root_key;
314 struct extent_buffer *eb;
315 int ret = 0;
316 int root_level;
317 int level = ref->level;
318 int index;
319
320 root_key.objectid = ref->root_id;
321 root_key.type = BTRFS_ROOT_ITEM_KEY;
322 root_key.offset = (u64)-1;
323
324 index = srcu_read_lock(&fs_info->subvol_srcu);
325
326 root = btrfs_read_fs_root_no_name(fs_info, &root_key);
327 if (IS_ERR(root)) {
328 srcu_read_unlock(&fs_info->subvol_srcu, index);
329 ret = PTR_ERR(root);
330 goto out;
331 }
332
333 if (path->search_commit_root)
334 root_level = btrfs_header_level(root->commit_root);
335 else
336 root_level = btrfs_old_root_level(root, time_seq);
337
338 if (root_level + 1 == level) {
339 srcu_read_unlock(&fs_info->subvol_srcu, index);
340 goto out;
341 }
342
343 path->lowest_level = level;
344 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
345
346 /* root node has been locked, we can release @subvol_srcu safely here */
347 srcu_read_unlock(&fs_info->subvol_srcu, index);
348
349 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
350 "%d for key (%llu %u %llu)\n",
351 ref->root_id, level, ref->count, ret,
352 ref->key_for_search.objectid, ref->key_for_search.type,
353 ref->key_for_search.offset);
354 if (ret < 0)
355 goto out;
356
357 eb = path->nodes[level];
358 while (!eb) {
359 if (WARN_ON(!level)) {
360 ret = 1;
361 goto out;
362 }
363 level--;
364 eb = path->nodes[level];
365 }
366
367 ret = add_all_parents(root, path, parents, ref, level, time_seq,
368 extent_item_pos, total_refs);
369 out:
370 path->lowest_level = 0;
371 btrfs_release_path(path);
372 return ret;
373 }
374
375 /*
376 * resolve all indirect backrefs from the list
377 */
378 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
379 struct btrfs_path *path, u64 time_seq,
380 struct list_head *head,
381 const u64 *extent_item_pos, u64 total_refs)
382 {
383 int err;
384 int ret = 0;
385 struct __prelim_ref *ref;
386 struct __prelim_ref *ref_safe;
387 struct __prelim_ref *new_ref;
388 struct ulist *parents;
389 struct ulist_node *node;
390 struct ulist_iterator uiter;
391
392 parents = ulist_alloc(GFP_NOFS);
393 if (!parents)
394 return -ENOMEM;
395
396 /*
397 * _safe allows us to insert directly after the current item without
398 * iterating over the newly inserted items.
399 * we're also allowed to re-assign ref during iteration.
400 */
401 list_for_each_entry_safe(ref, ref_safe, head, list) {
402 if (ref->parent) /* already direct */
403 continue;
404 if (ref->count == 0)
405 continue;
406 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
407 parents, extent_item_pos,
408 total_refs);
409 /*
410 * we can only tolerate ENOENT,otherwise,we should catch error
411 * and return directly.
412 */
413 if (err == -ENOENT) {
414 continue;
415 } else if (err) {
416 ret = err;
417 goto out;
418 }
419
420 /* we put the first parent into the ref at hand */
421 ULIST_ITER_INIT(&uiter);
422 node = ulist_next(parents, &uiter);
423 ref->parent = node ? node->val : 0;
424 ref->inode_list = node ?
425 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
426
427 /* additional parents require new refs being added here */
428 while ((node = ulist_next(parents, &uiter))) {
429 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
430 GFP_NOFS);
431 if (!new_ref) {
432 ret = -ENOMEM;
433 goto out;
434 }
435 memcpy(new_ref, ref, sizeof(*ref));
436 new_ref->parent = node->val;
437 new_ref->inode_list = (struct extent_inode_elem *)
438 (uintptr_t)node->aux;
439 list_add(&new_ref->list, &ref->list);
440 }
441 ulist_reinit(parents);
442 }
443 out:
444 ulist_free(parents);
445 return ret;
446 }
447
448 static inline int ref_for_same_block(struct __prelim_ref *ref1,
449 struct __prelim_ref *ref2)
450 {
451 if (ref1->level != ref2->level)
452 return 0;
453 if (ref1->root_id != ref2->root_id)
454 return 0;
455 if (ref1->key_for_search.type != ref2->key_for_search.type)
456 return 0;
457 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
458 return 0;
459 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
460 return 0;
461 if (ref1->parent != ref2->parent)
462 return 0;
463
464 return 1;
465 }
466
467 /*
468 * read tree blocks and add keys where required.
469 */
470 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
471 struct list_head *head)
472 {
473 struct list_head *pos;
474 struct extent_buffer *eb;
475
476 list_for_each(pos, head) {
477 struct __prelim_ref *ref;
478 ref = list_entry(pos, struct __prelim_ref, list);
479
480 if (ref->parent)
481 continue;
482 if (ref->key_for_search.type)
483 continue;
484 BUG_ON(!ref->wanted_disk_byte);
485 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
486 fs_info->tree_root->leafsize, 0);
487 if (!eb || !extent_buffer_uptodate(eb)) {
488 free_extent_buffer(eb);
489 return -EIO;
490 }
491 btrfs_tree_read_lock(eb);
492 if (btrfs_header_level(eb) == 0)
493 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
494 else
495 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
496 btrfs_tree_read_unlock(eb);
497 free_extent_buffer(eb);
498 }
499 return 0;
500 }
501
502 /*
503 * merge two lists of backrefs and adjust counts accordingly
504 *
505 * mode = 1: merge identical keys, if key is set
506 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
507 * additionally, we could even add a key range for the blocks we
508 * looked into to merge even more (-> replace unresolved refs by those
509 * having a parent).
510 * mode = 2: merge identical parents
511 */
512 static void __merge_refs(struct list_head *head, int mode)
513 {
514 struct list_head *pos1;
515
516 list_for_each(pos1, head) {
517 struct list_head *n2;
518 struct list_head *pos2;
519 struct __prelim_ref *ref1;
520
521 ref1 = list_entry(pos1, struct __prelim_ref, list);
522
523 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
524 pos2 = n2, n2 = pos2->next) {
525 struct __prelim_ref *ref2;
526 struct __prelim_ref *xchg;
527 struct extent_inode_elem *eie;
528
529 ref2 = list_entry(pos2, struct __prelim_ref, list);
530
531 if (mode == 1) {
532 if (!ref_for_same_block(ref1, ref2))
533 continue;
534 if (!ref1->parent && ref2->parent) {
535 xchg = ref1;
536 ref1 = ref2;
537 ref2 = xchg;
538 }
539 } else {
540 if (ref1->parent != ref2->parent)
541 continue;
542 }
543
544 eie = ref1->inode_list;
545 while (eie && eie->next)
546 eie = eie->next;
547 if (eie)
548 eie->next = ref2->inode_list;
549 else
550 ref1->inode_list = ref2->inode_list;
551 ref1->count += ref2->count;
552
553 list_del(&ref2->list);
554 kmem_cache_free(btrfs_prelim_ref_cache, ref2);
555 }
556
557 }
558 }
559
560 /*
561 * add all currently queued delayed refs from this head whose seq nr is
562 * smaller or equal that seq to the list
563 */
564 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
565 struct list_head *prefs, u64 *total_refs)
566 {
567 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
568 struct rb_node *n = &head->node.rb_node;
569 struct btrfs_key key;
570 struct btrfs_key op_key = {0};
571 int sgn;
572 int ret = 0;
573
574 if (extent_op && extent_op->update_key)
575 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
576
577 spin_lock(&head->lock);
578 n = rb_first(&head->ref_root);
579 while (n) {
580 struct btrfs_delayed_ref_node *node;
581 node = rb_entry(n, struct btrfs_delayed_ref_node,
582 rb_node);
583 n = rb_next(n);
584 if (node->seq > seq)
585 continue;
586
587 switch (node->action) {
588 case BTRFS_ADD_DELAYED_EXTENT:
589 case BTRFS_UPDATE_DELAYED_HEAD:
590 WARN_ON(1);
591 continue;
592 case BTRFS_ADD_DELAYED_REF:
593 sgn = 1;
594 break;
595 case BTRFS_DROP_DELAYED_REF:
596 sgn = -1;
597 break;
598 default:
599 BUG_ON(1);
600 }
601 *total_refs += (node->ref_mod * sgn);
602 switch (node->type) {
603 case BTRFS_TREE_BLOCK_REF_KEY: {
604 struct btrfs_delayed_tree_ref *ref;
605
606 ref = btrfs_delayed_node_to_tree_ref(node);
607 ret = __add_prelim_ref(prefs, ref->root, &op_key,
608 ref->level + 1, 0, node->bytenr,
609 node->ref_mod * sgn, GFP_ATOMIC);
610 break;
611 }
612 case BTRFS_SHARED_BLOCK_REF_KEY: {
613 struct btrfs_delayed_tree_ref *ref;
614
615 ref = btrfs_delayed_node_to_tree_ref(node);
616 ret = __add_prelim_ref(prefs, ref->root, NULL,
617 ref->level + 1, ref->parent,
618 node->bytenr,
619 node->ref_mod * sgn, GFP_ATOMIC);
620 break;
621 }
622 case BTRFS_EXTENT_DATA_REF_KEY: {
623 struct btrfs_delayed_data_ref *ref;
624 ref = btrfs_delayed_node_to_data_ref(node);
625
626 key.objectid = ref->objectid;
627 key.type = BTRFS_EXTENT_DATA_KEY;
628 key.offset = ref->offset;
629 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
630 node->bytenr,
631 node->ref_mod * sgn, GFP_ATOMIC);
632 break;
633 }
634 case BTRFS_SHARED_DATA_REF_KEY: {
635 struct btrfs_delayed_data_ref *ref;
636
637 ref = btrfs_delayed_node_to_data_ref(node);
638
639 key.objectid = ref->objectid;
640 key.type = BTRFS_EXTENT_DATA_KEY;
641 key.offset = ref->offset;
642 ret = __add_prelim_ref(prefs, ref->root, &key, 0,
643 ref->parent, node->bytenr,
644 node->ref_mod * sgn, GFP_ATOMIC);
645 break;
646 }
647 default:
648 WARN_ON(1);
649 }
650 if (ret)
651 break;
652 }
653 spin_unlock(&head->lock);
654 return ret;
655 }
656
657 /*
658 * add all inline backrefs for bytenr to the list
659 */
660 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
661 struct btrfs_path *path, u64 bytenr,
662 int *info_level, struct list_head *prefs,
663 u64 *total_refs)
664 {
665 int ret = 0;
666 int slot;
667 struct extent_buffer *leaf;
668 struct btrfs_key key;
669 struct btrfs_key found_key;
670 unsigned long ptr;
671 unsigned long end;
672 struct btrfs_extent_item *ei;
673 u64 flags;
674 u64 item_size;
675
676 /*
677 * enumerate all inline refs
678 */
679 leaf = path->nodes[0];
680 slot = path->slots[0];
681
682 item_size = btrfs_item_size_nr(leaf, slot);
683 BUG_ON(item_size < sizeof(*ei));
684
685 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
686 flags = btrfs_extent_flags(leaf, ei);
687 *total_refs += btrfs_extent_refs(leaf, ei);
688 btrfs_item_key_to_cpu(leaf, &found_key, slot);
689
690 ptr = (unsigned long)(ei + 1);
691 end = (unsigned long)ei + item_size;
692
693 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
694 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
695 struct btrfs_tree_block_info *info;
696
697 info = (struct btrfs_tree_block_info *)ptr;
698 *info_level = btrfs_tree_block_level(leaf, info);
699 ptr += sizeof(struct btrfs_tree_block_info);
700 BUG_ON(ptr > end);
701 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
702 *info_level = found_key.offset;
703 } else {
704 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
705 }
706
707 while (ptr < end) {
708 struct btrfs_extent_inline_ref *iref;
709 u64 offset;
710 int type;
711
712 iref = (struct btrfs_extent_inline_ref *)ptr;
713 type = btrfs_extent_inline_ref_type(leaf, iref);
714 offset = btrfs_extent_inline_ref_offset(leaf, iref);
715
716 switch (type) {
717 case BTRFS_SHARED_BLOCK_REF_KEY:
718 ret = __add_prelim_ref(prefs, 0, NULL,
719 *info_level + 1, offset,
720 bytenr, 1, GFP_NOFS);
721 break;
722 case BTRFS_SHARED_DATA_REF_KEY: {
723 struct btrfs_shared_data_ref *sdref;
724 int count;
725
726 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
727 count = btrfs_shared_data_ref_count(leaf, sdref);
728 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
729 bytenr, count, GFP_NOFS);
730 break;
731 }
732 case BTRFS_TREE_BLOCK_REF_KEY:
733 ret = __add_prelim_ref(prefs, offset, NULL,
734 *info_level + 1, 0,
735 bytenr, 1, GFP_NOFS);
736 break;
737 case BTRFS_EXTENT_DATA_REF_KEY: {
738 struct btrfs_extent_data_ref *dref;
739 int count;
740 u64 root;
741
742 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
743 count = btrfs_extent_data_ref_count(leaf, dref);
744 key.objectid = btrfs_extent_data_ref_objectid(leaf,
745 dref);
746 key.type = BTRFS_EXTENT_DATA_KEY;
747 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
748 root = btrfs_extent_data_ref_root(leaf, dref);
749 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
750 bytenr, count, GFP_NOFS);
751 break;
752 }
753 default:
754 WARN_ON(1);
755 }
756 if (ret)
757 return ret;
758 ptr += btrfs_extent_inline_ref_size(type);
759 }
760
761 return 0;
762 }
763
764 /*
765 * add all non-inline backrefs for bytenr to the list
766 */
767 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
768 struct btrfs_path *path, u64 bytenr,
769 int info_level, struct list_head *prefs)
770 {
771 struct btrfs_root *extent_root = fs_info->extent_root;
772 int ret;
773 int slot;
774 struct extent_buffer *leaf;
775 struct btrfs_key key;
776
777 while (1) {
778 ret = btrfs_next_item(extent_root, path);
779 if (ret < 0)
780 break;
781 if (ret) {
782 ret = 0;
783 break;
784 }
785
786 slot = path->slots[0];
787 leaf = path->nodes[0];
788 btrfs_item_key_to_cpu(leaf, &key, slot);
789
790 if (key.objectid != bytenr)
791 break;
792 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
793 continue;
794 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
795 break;
796
797 switch (key.type) {
798 case BTRFS_SHARED_BLOCK_REF_KEY:
799 ret = __add_prelim_ref(prefs, 0, NULL,
800 info_level + 1, key.offset,
801 bytenr, 1, GFP_NOFS);
802 break;
803 case BTRFS_SHARED_DATA_REF_KEY: {
804 struct btrfs_shared_data_ref *sdref;
805 int count;
806
807 sdref = btrfs_item_ptr(leaf, slot,
808 struct btrfs_shared_data_ref);
809 count = btrfs_shared_data_ref_count(leaf, sdref);
810 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
811 bytenr, count, GFP_NOFS);
812 break;
813 }
814 case BTRFS_TREE_BLOCK_REF_KEY:
815 ret = __add_prelim_ref(prefs, key.offset, NULL,
816 info_level + 1, 0,
817 bytenr, 1, GFP_NOFS);
818 break;
819 case BTRFS_EXTENT_DATA_REF_KEY: {
820 struct btrfs_extent_data_ref *dref;
821 int count;
822 u64 root;
823
824 dref = btrfs_item_ptr(leaf, slot,
825 struct btrfs_extent_data_ref);
826 count = btrfs_extent_data_ref_count(leaf, dref);
827 key.objectid = btrfs_extent_data_ref_objectid(leaf,
828 dref);
829 key.type = BTRFS_EXTENT_DATA_KEY;
830 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
831 root = btrfs_extent_data_ref_root(leaf, dref);
832 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
833 bytenr, count, GFP_NOFS);
834 break;
835 }
836 default:
837 WARN_ON(1);
838 }
839 if (ret)
840 return ret;
841
842 }
843
844 return ret;
845 }
846
847 /*
848 * this adds all existing backrefs (inline backrefs, backrefs and delayed
849 * refs) for the given bytenr to the refs list, merges duplicates and resolves
850 * indirect refs to their parent bytenr.
851 * When roots are found, they're added to the roots list
852 *
853 * FIXME some caching might speed things up
854 */
855 static int find_parent_nodes(struct btrfs_trans_handle *trans,
856 struct btrfs_fs_info *fs_info, u64 bytenr,
857 u64 time_seq, struct ulist *refs,
858 struct ulist *roots, const u64 *extent_item_pos)
859 {
860 struct btrfs_key key;
861 struct btrfs_path *path;
862 struct btrfs_delayed_ref_root *delayed_refs = NULL;
863 struct btrfs_delayed_ref_head *head;
864 int info_level = 0;
865 int ret;
866 struct list_head prefs_delayed;
867 struct list_head prefs;
868 struct __prelim_ref *ref;
869 struct extent_inode_elem *eie = NULL;
870 u64 total_refs = 0;
871
872 INIT_LIST_HEAD(&prefs);
873 INIT_LIST_HEAD(&prefs_delayed);
874
875 key.objectid = bytenr;
876 key.offset = (u64)-1;
877 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
878 key.type = BTRFS_METADATA_ITEM_KEY;
879 else
880 key.type = BTRFS_EXTENT_ITEM_KEY;
881
882 path = btrfs_alloc_path();
883 if (!path)
884 return -ENOMEM;
885 if (!trans) {
886 path->search_commit_root = 1;
887 path->skip_locking = 1;
888 }
889
890 /*
891 * grab both a lock on the path and a lock on the delayed ref head.
892 * We need both to get a consistent picture of how the refs look
893 * at a specified point in time
894 */
895 again:
896 head = NULL;
897
898 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
899 if (ret < 0)
900 goto out;
901 BUG_ON(ret == 0);
902
903 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
904 if (trans && likely(trans->type != __TRANS_DUMMY)) {
905 #else
906 if (trans) {
907 #endif
908 /*
909 * look if there are updates for this ref queued and lock the
910 * head
911 */
912 delayed_refs = &trans->transaction->delayed_refs;
913 spin_lock(&delayed_refs->lock);
914 head = btrfs_find_delayed_ref_head(trans, bytenr);
915 if (head) {
916 if (!mutex_trylock(&head->mutex)) {
917 atomic_inc(&head->node.refs);
918 spin_unlock(&delayed_refs->lock);
919
920 btrfs_release_path(path);
921
922 /*
923 * Mutex was contended, block until it's
924 * released and try again
925 */
926 mutex_lock(&head->mutex);
927 mutex_unlock(&head->mutex);
928 btrfs_put_delayed_ref(&head->node);
929 goto again;
930 }
931 spin_unlock(&delayed_refs->lock);
932 ret = __add_delayed_refs(head, time_seq,
933 &prefs_delayed, &total_refs);
934 mutex_unlock(&head->mutex);
935 if (ret)
936 goto out;
937 } else {
938 spin_unlock(&delayed_refs->lock);
939 }
940 }
941
942 if (path->slots[0]) {
943 struct extent_buffer *leaf;
944 int slot;
945
946 path->slots[0]--;
947 leaf = path->nodes[0];
948 slot = path->slots[0];
949 btrfs_item_key_to_cpu(leaf, &key, slot);
950 if (key.objectid == bytenr &&
951 (key.type == BTRFS_EXTENT_ITEM_KEY ||
952 key.type == BTRFS_METADATA_ITEM_KEY)) {
953 ret = __add_inline_refs(fs_info, path, bytenr,
954 &info_level, &prefs,
955 &total_refs);
956 if (ret)
957 goto out;
958 ret = __add_keyed_refs(fs_info, path, bytenr,
959 info_level, &prefs);
960 if (ret)
961 goto out;
962 }
963 }
964 btrfs_release_path(path);
965
966 list_splice_init(&prefs_delayed, &prefs);
967
968 ret = __add_missing_keys(fs_info, &prefs);
969 if (ret)
970 goto out;
971
972 __merge_refs(&prefs, 1);
973
974 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
975 extent_item_pos, total_refs);
976 if (ret)
977 goto out;
978
979 __merge_refs(&prefs, 2);
980
981 while (!list_empty(&prefs)) {
982 ref = list_first_entry(&prefs, struct __prelim_ref, list);
983 WARN_ON(ref->count < 0);
984 if (roots && ref->count && ref->root_id && ref->parent == 0) {
985 /* no parent == root of tree */
986 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
987 if (ret < 0)
988 goto out;
989 }
990 if (ref->count && ref->parent) {
991 if (extent_item_pos && !ref->inode_list &&
992 ref->level == 0) {
993 u32 bsz;
994 struct extent_buffer *eb;
995 bsz = btrfs_level_size(fs_info->extent_root,
996 ref->level);
997 eb = read_tree_block(fs_info->extent_root,
998 ref->parent, bsz, 0);
999 if (!eb || !extent_buffer_uptodate(eb)) {
1000 free_extent_buffer(eb);
1001 ret = -EIO;
1002 goto out;
1003 }
1004 ret = find_extent_in_eb(eb, bytenr,
1005 *extent_item_pos, &eie);
1006 free_extent_buffer(eb);
1007 if (ret < 0)
1008 goto out;
1009 ref->inode_list = eie;
1010 }
1011 ret = ulist_add_merge(refs, ref->parent,
1012 (uintptr_t)ref->inode_list,
1013 (u64 *)&eie, GFP_NOFS);
1014 if (ret < 0)
1015 goto out;
1016 if (!ret && extent_item_pos) {
1017 /*
1018 * we've recorded that parent, so we must extend
1019 * its inode list here
1020 */
1021 BUG_ON(!eie);
1022 while (eie->next)
1023 eie = eie->next;
1024 eie->next = ref->inode_list;
1025 }
1026 eie = NULL;
1027 }
1028 list_del(&ref->list);
1029 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1030 }
1031
1032 out:
1033 btrfs_free_path(path);
1034 while (!list_empty(&prefs)) {
1035 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1036 list_del(&ref->list);
1037 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1038 }
1039 while (!list_empty(&prefs_delayed)) {
1040 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
1041 list);
1042 list_del(&ref->list);
1043 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1044 }
1045 if (ret < 0)
1046 free_inode_elem_list(eie);
1047 return ret;
1048 }
1049
1050 static void free_leaf_list(struct ulist *blocks)
1051 {
1052 struct ulist_node *node = NULL;
1053 struct extent_inode_elem *eie;
1054 struct ulist_iterator uiter;
1055
1056 ULIST_ITER_INIT(&uiter);
1057 while ((node = ulist_next(blocks, &uiter))) {
1058 if (!node->aux)
1059 continue;
1060 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1061 free_inode_elem_list(eie);
1062 node->aux = 0;
1063 }
1064
1065 ulist_free(blocks);
1066 }
1067
1068 /*
1069 * Finds all leafs with a reference to the specified combination of bytenr and
1070 * offset. key_list_head will point to a list of corresponding keys (caller must
1071 * free each list element). The leafs will be stored in the leafs ulist, which
1072 * must be freed with ulist_free.
1073 *
1074 * returns 0 on success, <0 on error
1075 */
1076 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1077 struct btrfs_fs_info *fs_info, u64 bytenr,
1078 u64 time_seq, struct ulist **leafs,
1079 const u64 *extent_item_pos)
1080 {
1081 int ret;
1082
1083 *leafs = ulist_alloc(GFP_NOFS);
1084 if (!*leafs)
1085 return -ENOMEM;
1086
1087 ret = find_parent_nodes(trans, fs_info, bytenr,
1088 time_seq, *leafs, NULL, extent_item_pos);
1089 if (ret < 0 && ret != -ENOENT) {
1090 free_leaf_list(*leafs);
1091 return ret;
1092 }
1093
1094 return 0;
1095 }
1096
1097 /*
1098 * walk all backrefs for a given extent to find all roots that reference this
1099 * extent. Walking a backref means finding all extents that reference this
1100 * extent and in turn walk the backrefs of those, too. Naturally this is a
1101 * recursive process, but here it is implemented in an iterative fashion: We
1102 * find all referencing extents for the extent in question and put them on a
1103 * list. In turn, we find all referencing extents for those, further appending
1104 * to the list. The way we iterate the list allows adding more elements after
1105 * the current while iterating. The process stops when we reach the end of the
1106 * list. Found roots are added to the roots list.
1107 *
1108 * returns 0 on success, < 0 on error.
1109 */
1110 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1111 struct btrfs_fs_info *fs_info, u64 bytenr,
1112 u64 time_seq, struct ulist **roots)
1113 {
1114 struct ulist *tmp;
1115 struct ulist_node *node = NULL;
1116 struct ulist_iterator uiter;
1117 int ret;
1118
1119 tmp = ulist_alloc(GFP_NOFS);
1120 if (!tmp)
1121 return -ENOMEM;
1122 *roots = ulist_alloc(GFP_NOFS);
1123 if (!*roots) {
1124 ulist_free(tmp);
1125 return -ENOMEM;
1126 }
1127
1128 ULIST_ITER_INIT(&uiter);
1129 while (1) {
1130 ret = find_parent_nodes(trans, fs_info, bytenr,
1131 time_seq, tmp, *roots, NULL);
1132 if (ret < 0 && ret != -ENOENT) {
1133 ulist_free(tmp);
1134 ulist_free(*roots);
1135 return ret;
1136 }
1137 node = ulist_next(tmp, &uiter);
1138 if (!node)
1139 break;
1140 bytenr = node->val;
1141 cond_resched();
1142 }
1143
1144 ulist_free(tmp);
1145 return 0;
1146 }
1147
1148 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1149 struct btrfs_fs_info *fs_info, u64 bytenr,
1150 u64 time_seq, struct ulist **roots)
1151 {
1152 int ret;
1153
1154 if (!trans)
1155 down_read(&fs_info->commit_root_sem);
1156 ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
1157 if (!trans)
1158 up_read(&fs_info->commit_root_sem);
1159 return ret;
1160 }
1161
1162 /*
1163 * this makes the path point to (inum INODE_ITEM ioff)
1164 */
1165 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1166 struct btrfs_path *path)
1167 {
1168 struct btrfs_key key;
1169 return btrfs_find_item(fs_root, path, inum, ioff,
1170 BTRFS_INODE_ITEM_KEY, &key);
1171 }
1172
1173 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1174 struct btrfs_path *path,
1175 struct btrfs_key *found_key)
1176 {
1177 return btrfs_find_item(fs_root, path, inum, ioff,
1178 BTRFS_INODE_REF_KEY, found_key);
1179 }
1180
1181 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1182 u64 start_off, struct btrfs_path *path,
1183 struct btrfs_inode_extref **ret_extref,
1184 u64 *found_off)
1185 {
1186 int ret, slot;
1187 struct btrfs_key key;
1188 struct btrfs_key found_key;
1189 struct btrfs_inode_extref *extref;
1190 struct extent_buffer *leaf;
1191 unsigned long ptr;
1192
1193 key.objectid = inode_objectid;
1194 btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1195 key.offset = start_off;
1196
1197 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1198 if (ret < 0)
1199 return ret;
1200
1201 while (1) {
1202 leaf = path->nodes[0];
1203 slot = path->slots[0];
1204 if (slot >= btrfs_header_nritems(leaf)) {
1205 /*
1206 * If the item at offset is not found,
1207 * btrfs_search_slot will point us to the slot
1208 * where it should be inserted. In our case
1209 * that will be the slot directly before the
1210 * next INODE_REF_KEY_V2 item. In the case
1211 * that we're pointing to the last slot in a
1212 * leaf, we must move one leaf over.
1213 */
1214 ret = btrfs_next_leaf(root, path);
1215 if (ret) {
1216 if (ret >= 1)
1217 ret = -ENOENT;
1218 break;
1219 }
1220 continue;
1221 }
1222
1223 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1224
1225 /*
1226 * Check that we're still looking at an extended ref key for
1227 * this particular objectid. If we have different
1228 * objectid or type then there are no more to be found
1229 * in the tree and we can exit.
1230 */
1231 ret = -ENOENT;
1232 if (found_key.objectid != inode_objectid)
1233 break;
1234 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1235 break;
1236
1237 ret = 0;
1238 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1239 extref = (struct btrfs_inode_extref *)ptr;
1240 *ret_extref = extref;
1241 if (found_off)
1242 *found_off = found_key.offset;
1243 break;
1244 }
1245
1246 return ret;
1247 }
1248
1249 /*
1250 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1251 * Elements of the path are separated by '/' and the path is guaranteed to be
1252 * 0-terminated. the path is only given within the current file system.
1253 * Therefore, it never starts with a '/'. the caller is responsible to provide
1254 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1255 * the start point of the resulting string is returned. this pointer is within
1256 * dest, normally.
1257 * in case the path buffer would overflow, the pointer is decremented further
1258 * as if output was written to the buffer, though no more output is actually
1259 * generated. that way, the caller can determine how much space would be
1260 * required for the path to fit into the buffer. in that case, the returned
1261 * value will be smaller than dest. callers must check this!
1262 */
1263 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1264 u32 name_len, unsigned long name_off,
1265 struct extent_buffer *eb_in, u64 parent,
1266 char *dest, u32 size)
1267 {
1268 int slot;
1269 u64 next_inum;
1270 int ret;
1271 s64 bytes_left = ((s64)size) - 1;
1272 struct extent_buffer *eb = eb_in;
1273 struct btrfs_key found_key;
1274 int leave_spinning = path->leave_spinning;
1275 struct btrfs_inode_ref *iref;
1276
1277 if (bytes_left >= 0)
1278 dest[bytes_left] = '\0';
1279
1280 path->leave_spinning = 1;
1281 while (1) {
1282 bytes_left -= name_len;
1283 if (bytes_left >= 0)
1284 read_extent_buffer(eb, dest + bytes_left,
1285 name_off, name_len);
1286 if (eb != eb_in) {
1287 btrfs_tree_read_unlock_blocking(eb);
1288 free_extent_buffer(eb);
1289 }
1290 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1291 if (ret > 0)
1292 ret = -ENOENT;
1293 if (ret)
1294 break;
1295
1296 next_inum = found_key.offset;
1297
1298 /* regular exit ahead */
1299 if (parent == next_inum)
1300 break;
1301
1302 slot = path->slots[0];
1303 eb = path->nodes[0];
1304 /* make sure we can use eb after releasing the path */
1305 if (eb != eb_in) {
1306 atomic_inc(&eb->refs);
1307 btrfs_tree_read_lock(eb);
1308 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1309 }
1310 btrfs_release_path(path);
1311 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1312
1313 name_len = btrfs_inode_ref_name_len(eb, iref);
1314 name_off = (unsigned long)(iref + 1);
1315
1316 parent = next_inum;
1317 --bytes_left;
1318 if (bytes_left >= 0)
1319 dest[bytes_left] = '/';
1320 }
1321
1322 btrfs_release_path(path);
1323 path->leave_spinning = leave_spinning;
1324
1325 if (ret)
1326 return ERR_PTR(ret);
1327
1328 return dest + bytes_left;
1329 }
1330
1331 /*
1332 * this makes the path point to (logical EXTENT_ITEM *)
1333 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1334 * tree blocks and <0 on error.
1335 */
1336 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1337 struct btrfs_path *path, struct btrfs_key *found_key,
1338 u64 *flags_ret)
1339 {
1340 int ret;
1341 u64 flags;
1342 u64 size = 0;
1343 u32 item_size;
1344 struct extent_buffer *eb;
1345 struct btrfs_extent_item *ei;
1346 struct btrfs_key key;
1347
1348 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1349 key.type = BTRFS_METADATA_ITEM_KEY;
1350 else
1351 key.type = BTRFS_EXTENT_ITEM_KEY;
1352 key.objectid = logical;
1353 key.offset = (u64)-1;
1354
1355 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1356 if (ret < 0)
1357 return ret;
1358
1359 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1360 if (ret) {
1361 if (ret > 0)
1362 ret = -ENOENT;
1363 return ret;
1364 }
1365 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1366 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1367 size = fs_info->extent_root->leafsize;
1368 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1369 size = found_key->offset;
1370
1371 if (found_key->objectid > logical ||
1372 found_key->objectid + size <= logical) {
1373 pr_debug("logical %llu is not within any extent\n", logical);
1374 return -ENOENT;
1375 }
1376
1377 eb = path->nodes[0];
1378 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1379 BUG_ON(item_size < sizeof(*ei));
1380
1381 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1382 flags = btrfs_extent_flags(eb, ei);
1383
1384 pr_debug("logical %llu is at position %llu within the extent (%llu "
1385 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1386 logical, logical - found_key->objectid, found_key->objectid,
1387 found_key->offset, flags, item_size);
1388
1389 WARN_ON(!flags_ret);
1390 if (flags_ret) {
1391 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1392 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1393 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1394 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1395 else
1396 BUG_ON(1);
1397 return 0;
1398 }
1399
1400 return -EIO;
1401 }
1402
1403 /*
1404 * helper function to iterate extent inline refs. ptr must point to a 0 value
1405 * for the first call and may be modified. it is used to track state.
1406 * if more refs exist, 0 is returned and the next call to
1407 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1408 * next ref. after the last ref was processed, 1 is returned.
1409 * returns <0 on error
1410 */
1411 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1412 struct btrfs_extent_item *ei, u32 item_size,
1413 struct btrfs_extent_inline_ref **out_eiref,
1414 int *out_type)
1415 {
1416 unsigned long end;
1417 u64 flags;
1418 struct btrfs_tree_block_info *info;
1419
1420 if (!*ptr) {
1421 /* first call */
1422 flags = btrfs_extent_flags(eb, ei);
1423 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1424 info = (struct btrfs_tree_block_info *)(ei + 1);
1425 *out_eiref =
1426 (struct btrfs_extent_inline_ref *)(info + 1);
1427 } else {
1428 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1429 }
1430 *ptr = (unsigned long)*out_eiref;
1431 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1432 return -ENOENT;
1433 }
1434
1435 end = (unsigned long)ei + item_size;
1436 *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1437 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1438
1439 *ptr += btrfs_extent_inline_ref_size(*out_type);
1440 WARN_ON(*ptr > end);
1441 if (*ptr == end)
1442 return 1; /* last */
1443
1444 return 0;
1445 }
1446
1447 /*
1448 * reads the tree block backref for an extent. tree level and root are returned
1449 * through out_level and out_root. ptr must point to a 0 value for the first
1450 * call and may be modified (see __get_extent_inline_ref comment).
1451 * returns 0 if data was provided, 1 if there was no more data to provide or
1452 * <0 on error.
1453 */
1454 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1455 struct btrfs_extent_item *ei, u32 item_size,
1456 u64 *out_root, u8 *out_level)
1457 {
1458 int ret;
1459 int type;
1460 struct btrfs_tree_block_info *info;
1461 struct btrfs_extent_inline_ref *eiref;
1462
1463 if (*ptr == (unsigned long)-1)
1464 return 1;
1465
1466 while (1) {
1467 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1468 &eiref, &type);
1469 if (ret < 0)
1470 return ret;
1471
1472 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1473 type == BTRFS_SHARED_BLOCK_REF_KEY)
1474 break;
1475
1476 if (ret == 1)
1477 return 1;
1478 }
1479
1480 /* we can treat both ref types equally here */
1481 info = (struct btrfs_tree_block_info *)(ei + 1);
1482 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1483 *out_level = btrfs_tree_block_level(eb, info);
1484
1485 if (ret == 1)
1486 *ptr = (unsigned long)-1;
1487
1488 return 0;
1489 }
1490
1491 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1492 u64 root, u64 extent_item_objectid,
1493 iterate_extent_inodes_t *iterate, void *ctx)
1494 {
1495 struct extent_inode_elem *eie;
1496 int ret = 0;
1497
1498 for (eie = inode_list; eie; eie = eie->next) {
1499 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1500 "root %llu\n", extent_item_objectid,
1501 eie->inum, eie->offset, root);
1502 ret = iterate(eie->inum, eie->offset, root, ctx);
1503 if (ret) {
1504 pr_debug("stopping iteration for %llu due to ret=%d\n",
1505 extent_item_objectid, ret);
1506 break;
1507 }
1508 }
1509
1510 return ret;
1511 }
1512
1513 /*
1514 * calls iterate() for every inode that references the extent identified by
1515 * the given parameters.
1516 * when the iterator function returns a non-zero value, iteration stops.
1517 */
1518 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1519 u64 extent_item_objectid, u64 extent_item_pos,
1520 int search_commit_root,
1521 iterate_extent_inodes_t *iterate, void *ctx)
1522 {
1523 int ret;
1524 struct btrfs_trans_handle *trans = NULL;
1525 struct ulist *refs = NULL;
1526 struct ulist *roots = NULL;
1527 struct ulist_node *ref_node = NULL;
1528 struct ulist_node *root_node = NULL;
1529 struct seq_list tree_mod_seq_elem = {};
1530 struct ulist_iterator ref_uiter;
1531 struct ulist_iterator root_uiter;
1532
1533 pr_debug("resolving all inodes for extent %llu\n",
1534 extent_item_objectid);
1535
1536 if (!search_commit_root) {
1537 trans = btrfs_join_transaction(fs_info->extent_root);
1538 if (IS_ERR(trans))
1539 return PTR_ERR(trans);
1540 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1541 } else {
1542 down_read(&fs_info->commit_root_sem);
1543 }
1544
1545 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1546 tree_mod_seq_elem.seq, &refs,
1547 &extent_item_pos);
1548 if (ret)
1549 goto out;
1550
1551 ULIST_ITER_INIT(&ref_uiter);
1552 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1553 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
1554 tree_mod_seq_elem.seq, &roots);
1555 if (ret)
1556 break;
1557 ULIST_ITER_INIT(&root_uiter);
1558 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1559 pr_debug("root %llu references leaf %llu, data list "
1560 "%#llx\n", root_node->val, ref_node->val,
1561 ref_node->aux);
1562 ret = iterate_leaf_refs((struct extent_inode_elem *)
1563 (uintptr_t)ref_node->aux,
1564 root_node->val,
1565 extent_item_objectid,
1566 iterate, ctx);
1567 }
1568 ulist_free(roots);
1569 }
1570
1571 free_leaf_list(refs);
1572 out:
1573 if (!search_commit_root) {
1574 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1575 btrfs_end_transaction(trans, fs_info->extent_root);
1576 } else {
1577 up_read(&fs_info->commit_root_sem);
1578 }
1579
1580 return ret;
1581 }
1582
1583 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1584 struct btrfs_path *path,
1585 iterate_extent_inodes_t *iterate, void *ctx)
1586 {
1587 int ret;
1588 u64 extent_item_pos;
1589 u64 flags = 0;
1590 struct btrfs_key found_key;
1591 int search_commit_root = path->search_commit_root;
1592
1593 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1594 btrfs_release_path(path);
1595 if (ret < 0)
1596 return ret;
1597 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1598 return -EINVAL;
1599
1600 extent_item_pos = logical - found_key.objectid;
1601 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1602 extent_item_pos, search_commit_root,
1603 iterate, ctx);
1604
1605 return ret;
1606 }
1607
1608 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1609 struct extent_buffer *eb, void *ctx);
1610
1611 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1612 struct btrfs_path *path,
1613 iterate_irefs_t *iterate, void *ctx)
1614 {
1615 int ret = 0;
1616 int slot;
1617 u32 cur;
1618 u32 len;
1619 u32 name_len;
1620 u64 parent = 0;
1621 int found = 0;
1622 struct extent_buffer *eb;
1623 struct btrfs_item *item;
1624 struct btrfs_inode_ref *iref;
1625 struct btrfs_key found_key;
1626
1627 while (!ret) {
1628 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1629 &found_key);
1630 if (ret < 0)
1631 break;
1632 if (ret) {
1633 ret = found ? 0 : -ENOENT;
1634 break;
1635 }
1636 ++found;
1637
1638 parent = found_key.offset;
1639 slot = path->slots[0];
1640 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1641 if (!eb) {
1642 ret = -ENOMEM;
1643 break;
1644 }
1645 extent_buffer_get(eb);
1646 btrfs_tree_read_lock(eb);
1647 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1648 btrfs_release_path(path);
1649
1650 item = btrfs_item_nr(slot);
1651 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1652
1653 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1654 name_len = btrfs_inode_ref_name_len(eb, iref);
1655 /* path must be released before calling iterate()! */
1656 pr_debug("following ref at offset %u for inode %llu in "
1657 "tree %llu\n", cur, found_key.objectid,
1658 fs_root->objectid);
1659 ret = iterate(parent, name_len,
1660 (unsigned long)(iref + 1), eb, ctx);
1661 if (ret)
1662 break;
1663 len = sizeof(*iref) + name_len;
1664 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1665 }
1666 btrfs_tree_read_unlock_blocking(eb);
1667 free_extent_buffer(eb);
1668 }
1669
1670 btrfs_release_path(path);
1671
1672 return ret;
1673 }
1674
1675 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1676 struct btrfs_path *path,
1677 iterate_irefs_t *iterate, void *ctx)
1678 {
1679 int ret;
1680 int slot;
1681 u64 offset = 0;
1682 u64 parent;
1683 int found = 0;
1684 struct extent_buffer *eb;
1685 struct btrfs_inode_extref *extref;
1686 struct extent_buffer *leaf;
1687 u32 item_size;
1688 u32 cur_offset;
1689 unsigned long ptr;
1690
1691 while (1) {
1692 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1693 &offset);
1694 if (ret < 0)
1695 break;
1696 if (ret) {
1697 ret = found ? 0 : -ENOENT;
1698 break;
1699 }
1700 ++found;
1701
1702 slot = path->slots[0];
1703 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1704 if (!eb) {
1705 ret = -ENOMEM;
1706 break;
1707 }
1708 extent_buffer_get(eb);
1709
1710 btrfs_tree_read_lock(eb);
1711 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1712 btrfs_release_path(path);
1713
1714 leaf = path->nodes[0];
1715 item_size = btrfs_item_size_nr(leaf, slot);
1716 ptr = btrfs_item_ptr_offset(leaf, slot);
1717 cur_offset = 0;
1718
1719 while (cur_offset < item_size) {
1720 u32 name_len;
1721
1722 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1723 parent = btrfs_inode_extref_parent(eb, extref);
1724 name_len = btrfs_inode_extref_name_len(eb, extref);
1725 ret = iterate(parent, name_len,
1726 (unsigned long)&extref->name, eb, ctx);
1727 if (ret)
1728 break;
1729
1730 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1731 cur_offset += sizeof(*extref);
1732 }
1733 btrfs_tree_read_unlock_blocking(eb);
1734 free_extent_buffer(eb);
1735
1736 offset++;
1737 }
1738
1739 btrfs_release_path(path);
1740
1741 return ret;
1742 }
1743
1744 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1745 struct btrfs_path *path, iterate_irefs_t *iterate,
1746 void *ctx)
1747 {
1748 int ret;
1749 int found_refs = 0;
1750
1751 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1752 if (!ret)
1753 ++found_refs;
1754 else if (ret != -ENOENT)
1755 return ret;
1756
1757 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1758 if (ret == -ENOENT && found_refs)
1759 return 0;
1760
1761 return ret;
1762 }
1763
1764 /*
1765 * returns 0 if the path could be dumped (probably truncated)
1766 * returns <0 in case of an error
1767 */
1768 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1769 struct extent_buffer *eb, void *ctx)
1770 {
1771 struct inode_fs_paths *ipath = ctx;
1772 char *fspath;
1773 char *fspath_min;
1774 int i = ipath->fspath->elem_cnt;
1775 const int s_ptr = sizeof(char *);
1776 u32 bytes_left;
1777
1778 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1779 ipath->fspath->bytes_left - s_ptr : 0;
1780
1781 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1782 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1783 name_off, eb, inum, fspath_min, bytes_left);
1784 if (IS_ERR(fspath))
1785 return PTR_ERR(fspath);
1786
1787 if (fspath > fspath_min) {
1788 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1789 ++ipath->fspath->elem_cnt;
1790 ipath->fspath->bytes_left = fspath - fspath_min;
1791 } else {
1792 ++ipath->fspath->elem_missed;
1793 ipath->fspath->bytes_missing += fspath_min - fspath;
1794 ipath->fspath->bytes_left = 0;
1795 }
1796
1797 return 0;
1798 }
1799
1800 /*
1801 * this dumps all file system paths to the inode into the ipath struct, provided
1802 * is has been created large enough. each path is zero-terminated and accessed
1803 * from ipath->fspath->val[i].
1804 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1805 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1806 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1807 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1808 * have been needed to return all paths.
1809 */
1810 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1811 {
1812 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1813 inode_to_path, ipath);
1814 }
1815
1816 struct btrfs_data_container *init_data_container(u32 total_bytes)
1817 {
1818 struct btrfs_data_container *data;
1819 size_t alloc_bytes;
1820
1821 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1822 data = vmalloc(alloc_bytes);
1823 if (!data)
1824 return ERR_PTR(-ENOMEM);
1825
1826 if (total_bytes >= sizeof(*data)) {
1827 data->bytes_left = total_bytes - sizeof(*data);
1828 data->bytes_missing = 0;
1829 } else {
1830 data->bytes_missing = sizeof(*data) - total_bytes;
1831 data->bytes_left = 0;
1832 }
1833
1834 data->elem_cnt = 0;
1835 data->elem_missed = 0;
1836
1837 return data;
1838 }
1839
1840 /*
1841 * allocates space to return multiple file system paths for an inode.
1842 * total_bytes to allocate are passed, note that space usable for actual path
1843 * information will be total_bytes - sizeof(struct inode_fs_paths).
1844 * the returned pointer must be freed with free_ipath() in the end.
1845 */
1846 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1847 struct btrfs_path *path)
1848 {
1849 struct inode_fs_paths *ifp;
1850 struct btrfs_data_container *fspath;
1851
1852 fspath = init_data_container(total_bytes);
1853 if (IS_ERR(fspath))
1854 return (void *)fspath;
1855
1856 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1857 if (!ifp) {
1858 kfree(fspath);
1859 return ERR_PTR(-ENOMEM);
1860 }
1861
1862 ifp->btrfs_path = path;
1863 ifp->fspath = fspath;
1864 ifp->fs_root = fs_root;
1865
1866 return ifp;
1867 }
1868
1869 void free_ipath(struct inode_fs_paths *ipath)
1870 {
1871 if (!ipath)
1872 return;
1873 vfree(ipath->fspath);
1874 kfree(ipath);
1875 }
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