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Linux 3.15-rc1
[linux/fpc-iii.git] / fs / btrfs / backref.c
blob10db21fa09263786db6d094c64ee7b16a1c2c2ae
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 if (trans) {
904 /*
905 * look if there are updates for this ref queued and lock the
906 * head
907 */
908 delayed_refs = &trans->transaction->delayed_refs;
909 spin_lock(&delayed_refs->lock);
910 head = btrfs_find_delayed_ref_head(trans, bytenr);
911 if (head) {
912 if (!mutex_trylock(&head->mutex)) {
913 atomic_inc(&head->node.refs);
914 spin_unlock(&delayed_refs->lock);
915
916 btrfs_release_path(path);
917
918 /*
919 * Mutex was contended, block until it's
920 * released and try again
921 */
922 mutex_lock(&head->mutex);
923 mutex_unlock(&head->mutex);
924 btrfs_put_delayed_ref(&head->node);
925 goto again;
926 }
927 spin_unlock(&delayed_refs->lock);
928 ret = __add_delayed_refs(head, time_seq,
929 &prefs_delayed, &total_refs);
930 mutex_unlock(&head->mutex);
931 if (ret)
932 goto out;
933 } else {
934 spin_unlock(&delayed_refs->lock);
935 }
936 }
937
938 if (path->slots[0]) {
939 struct extent_buffer *leaf;
940 int slot;
941
942 path->slots[0]--;
943 leaf = path->nodes[0];
944 slot = path->slots[0];
945 btrfs_item_key_to_cpu(leaf, &key, slot);
946 if (key.objectid == bytenr &&
947 (key.type == BTRFS_EXTENT_ITEM_KEY ||
948 key.type == BTRFS_METADATA_ITEM_KEY)) {
949 ret = __add_inline_refs(fs_info, path, bytenr,
950 &info_level, &prefs,
951 &total_refs);
952 if (ret)
953 goto out;
954 ret = __add_keyed_refs(fs_info, path, bytenr,
955 info_level, &prefs);
956 if (ret)
957 goto out;
958 }
959 }
960 btrfs_release_path(path);
961
962 list_splice_init(&prefs_delayed, &prefs);
963
964 ret = __add_missing_keys(fs_info, &prefs);
965 if (ret)
966 goto out;
967
968 __merge_refs(&prefs, 1);
969
970 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
971 extent_item_pos, total_refs);
972 if (ret)
973 goto out;
974
975 __merge_refs(&prefs, 2);
976
977 while (!list_empty(&prefs)) {
978 ref = list_first_entry(&prefs, struct __prelim_ref, list);
979 WARN_ON(ref->count < 0);
980 if (roots && ref->count && ref->root_id && ref->parent == 0) {
981 /* no parent == root of tree */
982 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
983 if (ret < 0)
984 goto out;
985 }
986 if (ref->count && ref->parent) {
987 if (extent_item_pos && !ref->inode_list) {
988 u32 bsz;
989 struct extent_buffer *eb;
990 bsz = btrfs_level_size(fs_info->extent_root,
991 info_level);
992 eb = read_tree_block(fs_info->extent_root,
993 ref->parent, bsz, 0);
994 if (!eb || !extent_buffer_uptodate(eb)) {
995 free_extent_buffer(eb);
996 ret = -EIO;
997 goto out;
998 }
999 ret = find_extent_in_eb(eb, bytenr,
1000 *extent_item_pos, &eie);
1001 free_extent_buffer(eb);
1002 if (ret < 0)
1003 goto out;
1004 ref->inode_list = eie;
1005 }
1006 ret = ulist_add_merge(refs, ref->parent,
1007 (uintptr_t)ref->inode_list,
1008 (u64 *)&eie, GFP_NOFS);
1009 if (ret < 0)
1010 goto out;
1011 if (!ret && extent_item_pos) {
1012 /*
1013 * we've recorded that parent, so we must extend
1014 * its inode list here
1015 */
1016 BUG_ON(!eie);
1017 while (eie->next)
1018 eie = eie->next;
1019 eie->next = ref->inode_list;
1020 }
1021 eie = NULL;
1022 }
1023 list_del(&ref->list);
1024 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1025 }
1026
1027 out:
1028 btrfs_free_path(path);
1029 while (!list_empty(&prefs)) {
1030 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1031 list_del(&ref->list);
1032 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1033 }
1034 while (!list_empty(&prefs_delayed)) {
1035 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
1036 list);
1037 list_del(&ref->list);
1038 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1039 }
1040 if (ret < 0)
1041 free_inode_elem_list(eie);
1042 return ret;
1043 }
1044
1045 static void free_leaf_list(struct ulist *blocks)
1046 {
1047 struct ulist_node *node = NULL;
1048 struct extent_inode_elem *eie;
1049 struct ulist_iterator uiter;
1050
1051 ULIST_ITER_INIT(&uiter);
1052 while ((node = ulist_next(blocks, &uiter))) {
1053 if (!node->aux)
1054 continue;
1055 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1056 free_inode_elem_list(eie);
1057 node->aux = 0;
1058 }
1059
1060 ulist_free(blocks);
1061 }
1062
1063 /*
1064 * Finds all leafs with a reference to the specified combination of bytenr and
1065 * offset. key_list_head will point to a list of corresponding keys (caller must
1066 * free each list element). The leafs will be stored in the leafs ulist, which
1067 * must be freed with ulist_free.
1068 *
1069 * returns 0 on success, <0 on error
1070 */
1071 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1072 struct btrfs_fs_info *fs_info, u64 bytenr,
1073 u64 time_seq, struct ulist **leafs,
1074 const u64 *extent_item_pos)
1075 {
1076 int ret;
1077
1078 *leafs = ulist_alloc(GFP_NOFS);
1079 if (!*leafs)
1080 return -ENOMEM;
1081
1082 ret = find_parent_nodes(trans, fs_info, bytenr,
1083 time_seq, *leafs, NULL, extent_item_pos);
1084 if (ret < 0 && ret != -ENOENT) {
1085 free_leaf_list(*leafs);
1086 return ret;
1087 }
1088
1089 return 0;
1090 }
1091
1092 /*
1093 * walk all backrefs for a given extent to find all roots that reference this
1094 * extent. Walking a backref means finding all extents that reference this
1095 * extent and in turn walk the backrefs of those, too. Naturally this is a
1096 * recursive process, but here it is implemented in an iterative fashion: We
1097 * find all referencing extents for the extent in question and put them on a
1098 * list. In turn, we find all referencing extents for those, further appending
1099 * to the list. The way we iterate the list allows adding more elements after
1100 * the current while iterating. The process stops when we reach the end of the
1101 * list. Found roots are added to the roots list.
1102 *
1103 * returns 0 on success, < 0 on error.
1104 */
1105 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1106 struct btrfs_fs_info *fs_info, u64 bytenr,
1107 u64 time_seq, struct ulist **roots)
1108 {
1109 struct ulist *tmp;
1110 struct ulist_node *node = NULL;
1111 struct ulist_iterator uiter;
1112 int ret;
1113
1114 tmp = ulist_alloc(GFP_NOFS);
1115 if (!tmp)
1116 return -ENOMEM;
1117 *roots = ulist_alloc(GFP_NOFS);
1118 if (!*roots) {
1119 ulist_free(tmp);
1120 return -ENOMEM;
1121 }
1122
1123 ULIST_ITER_INIT(&uiter);
1124 while (1) {
1125 ret = find_parent_nodes(trans, fs_info, bytenr,
1126 time_seq, tmp, *roots, NULL);
1127 if (ret < 0 && ret != -ENOENT) {
1128 ulist_free(tmp);
1129 ulist_free(*roots);
1130 return ret;
1131 }
1132 node = ulist_next(tmp, &uiter);
1133 if (!node)
1134 break;
1135 bytenr = node->val;
1136 cond_resched();
1137 }
1138
1139 ulist_free(tmp);
1140 return 0;
1141 }
1142
1143 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1144 struct btrfs_fs_info *fs_info, u64 bytenr,
1145 u64 time_seq, struct ulist **roots)
1146 {
1147 int ret;
1148
1149 if (!trans)
1150 down_read(&fs_info->commit_root_sem);
1151 ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
1152 if (!trans)
1153 up_read(&fs_info->commit_root_sem);
1154 return ret;
1155 }
1156
1157 /*
1158 * this makes the path point to (inum INODE_ITEM ioff)
1159 */
1160 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1161 struct btrfs_path *path)
1162 {
1163 struct btrfs_key key;
1164 return btrfs_find_item(fs_root, path, inum, ioff,
1165 BTRFS_INODE_ITEM_KEY, &key);
1166 }
1167
1168 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1169 struct btrfs_path *path,
1170 struct btrfs_key *found_key)
1171 {
1172 return btrfs_find_item(fs_root, path, inum, ioff,
1173 BTRFS_INODE_REF_KEY, found_key);
1174 }
1175
1176 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1177 u64 start_off, struct btrfs_path *path,
1178 struct btrfs_inode_extref **ret_extref,
1179 u64 *found_off)
1180 {
1181 int ret, slot;
1182 struct btrfs_key key;
1183 struct btrfs_key found_key;
1184 struct btrfs_inode_extref *extref;
1185 struct extent_buffer *leaf;
1186 unsigned long ptr;
1187
1188 key.objectid = inode_objectid;
1189 btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1190 key.offset = start_off;
1191
1192 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1193 if (ret < 0)
1194 return ret;
1195
1196 while (1) {
1197 leaf = path->nodes[0];
1198 slot = path->slots[0];
1199 if (slot >= btrfs_header_nritems(leaf)) {
1200 /*
1201 * If the item at offset is not found,
1202 * btrfs_search_slot will point us to the slot
1203 * where it should be inserted. In our case
1204 * that will be the slot directly before the
1205 * next INODE_REF_KEY_V2 item. In the case
1206 * that we're pointing to the last slot in a
1207 * leaf, we must move one leaf over.
1208 */
1209 ret = btrfs_next_leaf(root, path);
1210 if (ret) {
1211 if (ret >= 1)
1212 ret = -ENOENT;
1213 break;
1214 }
1215 continue;
1216 }
1217
1218 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1219
1220 /*
1221 * Check that we're still looking at an extended ref key for
1222 * this particular objectid. If we have different
1223 * objectid or type then there are no more to be found
1224 * in the tree and we can exit.
1225 */
1226 ret = -ENOENT;
1227 if (found_key.objectid != inode_objectid)
1228 break;
1229 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1230 break;
1231
1232 ret = 0;
1233 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1234 extref = (struct btrfs_inode_extref *)ptr;
1235 *ret_extref = extref;
1236 if (found_off)
1237 *found_off = found_key.offset;
1238 break;
1239 }
1240
1241 return ret;
1242 }
1243
1244 /*
1245 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1246 * Elements of the path are separated by '/' and the path is guaranteed to be
1247 * 0-terminated. the path is only given within the current file system.
1248 * Therefore, it never starts with a '/'. the caller is responsible to provide
1249 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1250 * the start point of the resulting string is returned. this pointer is within
1251 * dest, normally.
1252 * in case the path buffer would overflow, the pointer is decremented further
1253 * as if output was written to the buffer, though no more output is actually
1254 * generated. that way, the caller can determine how much space would be
1255 * required for the path to fit into the buffer. in that case, the returned
1256 * value will be smaller than dest. callers must check this!
1257 */
1258 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1259 u32 name_len, unsigned long name_off,
1260 struct extent_buffer *eb_in, u64 parent,
1261 char *dest, u32 size)
1262 {
1263 int slot;
1264 u64 next_inum;
1265 int ret;
1266 s64 bytes_left = ((s64)size) - 1;
1267 struct extent_buffer *eb = eb_in;
1268 struct btrfs_key found_key;
1269 int leave_spinning = path->leave_spinning;
1270 struct btrfs_inode_ref *iref;
1271
1272 if (bytes_left >= 0)
1273 dest[bytes_left] = '\0';
1274
1275 path->leave_spinning = 1;
1276 while (1) {
1277 bytes_left -= name_len;
1278 if (bytes_left >= 0)
1279 read_extent_buffer(eb, dest + bytes_left,
1280 name_off, name_len);
1281 if (eb != eb_in) {
1282 btrfs_tree_read_unlock_blocking(eb);
1283 free_extent_buffer(eb);
1284 }
1285 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1286 if (ret > 0)
1287 ret = -ENOENT;
1288 if (ret)
1289 break;
1290
1291 next_inum = found_key.offset;
1292
1293 /* regular exit ahead */
1294 if (parent == next_inum)
1295 break;
1296
1297 slot = path->slots[0];
1298 eb = path->nodes[0];
1299 /* make sure we can use eb after releasing the path */
1300 if (eb != eb_in) {
1301 atomic_inc(&eb->refs);
1302 btrfs_tree_read_lock(eb);
1303 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1304 }
1305 btrfs_release_path(path);
1306 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1307
1308 name_len = btrfs_inode_ref_name_len(eb, iref);
1309 name_off = (unsigned long)(iref + 1);
1310
1311 parent = next_inum;
1312 --bytes_left;
1313 if (bytes_left >= 0)
1314 dest[bytes_left] = '/';
1315 }
1316
1317 btrfs_release_path(path);
1318 path->leave_spinning = leave_spinning;
1319
1320 if (ret)
1321 return ERR_PTR(ret);
1322
1323 return dest + bytes_left;
1324 }
1325
1326 /*
1327 * this makes the path point to (logical EXTENT_ITEM *)
1328 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1329 * tree blocks and <0 on error.
1330 */
1331 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1332 struct btrfs_path *path, struct btrfs_key *found_key,
1333 u64 *flags_ret)
1334 {
1335 int ret;
1336 u64 flags;
1337 u64 size = 0;
1338 u32 item_size;
1339 struct extent_buffer *eb;
1340 struct btrfs_extent_item *ei;
1341 struct btrfs_key key;
1342
1343 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1344 key.type = BTRFS_METADATA_ITEM_KEY;
1345 else
1346 key.type = BTRFS_EXTENT_ITEM_KEY;
1347 key.objectid = logical;
1348 key.offset = (u64)-1;
1349
1350 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1351 if (ret < 0)
1352 return ret;
1353
1354 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1355 if (ret) {
1356 if (ret > 0)
1357 ret = -ENOENT;
1358 return ret;
1359 }
1360 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1361 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1362 size = fs_info->extent_root->leafsize;
1363 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1364 size = found_key->offset;
1365
1366 if (found_key->objectid > logical ||
1367 found_key->objectid + size <= logical) {
1368 pr_debug("logical %llu is not within any extent\n", logical);
1369 return -ENOENT;
1370 }
1371
1372 eb = path->nodes[0];
1373 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1374 BUG_ON(item_size < sizeof(*ei));
1375
1376 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1377 flags = btrfs_extent_flags(eb, ei);
1378
1379 pr_debug("logical %llu is at position %llu within the extent (%llu "
1380 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1381 logical, logical - found_key->objectid, found_key->objectid,
1382 found_key->offset, flags, item_size);
1383
1384 WARN_ON(!flags_ret);
1385 if (flags_ret) {
1386 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1387 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1388 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1389 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1390 else
1391 BUG_ON(1);
1392 return 0;
1393 }
1394
1395 return -EIO;
1396 }
1397
1398 /*
1399 * helper function to iterate extent inline refs. ptr must point to a 0 value
1400 * for the first call and may be modified. it is used to track state.
1401 * if more refs exist, 0 is returned and the next call to
1402 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1403 * next ref. after the last ref was processed, 1 is returned.
1404 * returns <0 on error
1405 */
1406 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1407 struct btrfs_extent_item *ei, u32 item_size,
1408 struct btrfs_extent_inline_ref **out_eiref,
1409 int *out_type)
1410 {
1411 unsigned long end;
1412 u64 flags;
1413 struct btrfs_tree_block_info *info;
1414
1415 if (!*ptr) {
1416 /* first call */
1417 flags = btrfs_extent_flags(eb, ei);
1418 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1419 info = (struct btrfs_tree_block_info *)(ei + 1);
1420 *out_eiref =
1421 (struct btrfs_extent_inline_ref *)(info + 1);
1422 } else {
1423 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1424 }
1425 *ptr = (unsigned long)*out_eiref;
1426 if ((void *)*ptr >= (void *)ei + item_size)
1427 return -ENOENT;
1428 }
1429
1430 end = (unsigned long)ei + item_size;
1431 *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1432 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1433
1434 *ptr += btrfs_extent_inline_ref_size(*out_type);
1435 WARN_ON(*ptr > end);
1436 if (*ptr == end)
1437 return 1; /* last */
1438
1439 return 0;
1440 }
1441
1442 /*
1443 * reads the tree block backref for an extent. tree level and root are returned
1444 * through out_level and out_root. ptr must point to a 0 value for the first
1445 * call and may be modified (see __get_extent_inline_ref comment).
1446 * returns 0 if data was provided, 1 if there was no more data to provide or
1447 * <0 on error.
1448 */
1449 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1450 struct btrfs_extent_item *ei, u32 item_size,
1451 u64 *out_root, u8 *out_level)
1452 {
1453 int ret;
1454 int type;
1455 struct btrfs_tree_block_info *info;
1456 struct btrfs_extent_inline_ref *eiref;
1457
1458 if (*ptr == (unsigned long)-1)
1459 return 1;
1460
1461 while (1) {
1462 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1463 &eiref, &type);
1464 if (ret < 0)
1465 return ret;
1466
1467 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1468 type == BTRFS_SHARED_BLOCK_REF_KEY)
1469 break;
1470
1471 if (ret == 1)
1472 return 1;
1473 }
1474
1475 /* we can treat both ref types equally here */
1476 info = (struct btrfs_tree_block_info *)(ei + 1);
1477 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1478 *out_level = btrfs_tree_block_level(eb, info);
1479
1480 if (ret == 1)
1481 *ptr = (unsigned long)-1;
1482
1483 return 0;
1484 }
1485
1486 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1487 u64 root, u64 extent_item_objectid,
1488 iterate_extent_inodes_t *iterate, void *ctx)
1489 {
1490 struct extent_inode_elem *eie;
1491 int ret = 0;
1492
1493 for (eie = inode_list; eie; eie = eie->next) {
1494 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1495 "root %llu\n", extent_item_objectid,
1496 eie->inum, eie->offset, root);
1497 ret = iterate(eie->inum, eie->offset, root, ctx);
1498 if (ret) {
1499 pr_debug("stopping iteration for %llu due to ret=%d\n",
1500 extent_item_objectid, ret);
1501 break;
1502 }
1503 }
1504
1505 return ret;
1506 }
1507
1508 /*
1509 * calls iterate() for every inode that references the extent identified by
1510 * the given parameters.
1511 * when the iterator function returns a non-zero value, iteration stops.
1512 */
1513 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1514 u64 extent_item_objectid, u64 extent_item_pos,
1515 int search_commit_root,
1516 iterate_extent_inodes_t *iterate, void *ctx)
1517 {
1518 int ret;
1519 struct btrfs_trans_handle *trans = NULL;
1520 struct ulist *refs = NULL;
1521 struct ulist *roots = NULL;
1522 struct ulist_node *ref_node = NULL;
1523 struct ulist_node *root_node = NULL;
1524 struct seq_list tree_mod_seq_elem = {};
1525 struct ulist_iterator ref_uiter;
1526 struct ulist_iterator root_uiter;
1527
1528 pr_debug("resolving all inodes for extent %llu\n",
1529 extent_item_objectid);
1530
1531 if (!search_commit_root) {
1532 trans = btrfs_join_transaction(fs_info->extent_root);
1533 if (IS_ERR(trans))
1534 return PTR_ERR(trans);
1535 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1536 } else {
1537 down_read(&fs_info->commit_root_sem);
1538 }
1539
1540 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1541 tree_mod_seq_elem.seq, &refs,
1542 &extent_item_pos);
1543 if (ret)
1544 goto out;
1545
1546 ULIST_ITER_INIT(&ref_uiter);
1547 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1548 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
1549 tree_mod_seq_elem.seq, &roots);
1550 if (ret)
1551 break;
1552 ULIST_ITER_INIT(&root_uiter);
1553 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1554 pr_debug("root %llu references leaf %llu, data list "
1555 "%#llx\n", root_node->val, ref_node->val,
1556 ref_node->aux);
1557 ret = iterate_leaf_refs((struct extent_inode_elem *)
1558 (uintptr_t)ref_node->aux,
1559 root_node->val,
1560 extent_item_objectid,
1561 iterate, ctx);
1562 }
1563 ulist_free(roots);
1564 }
1565
1566 free_leaf_list(refs);
1567 out:
1568 if (!search_commit_root) {
1569 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1570 btrfs_end_transaction(trans, fs_info->extent_root);
1571 } else {
1572 up_read(&fs_info->commit_root_sem);
1573 }
1574
1575 return ret;
1576 }
1577
1578 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1579 struct btrfs_path *path,
1580 iterate_extent_inodes_t *iterate, void *ctx)
1581 {
1582 int ret;
1583 u64 extent_item_pos;
1584 u64 flags = 0;
1585 struct btrfs_key found_key;
1586 int search_commit_root = path->search_commit_root;
1587
1588 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1589 btrfs_release_path(path);
1590 if (ret < 0)
1591 return ret;
1592 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1593 return -EINVAL;
1594
1595 extent_item_pos = logical - found_key.objectid;
1596 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1597 extent_item_pos, search_commit_root,
1598 iterate, ctx);
1599
1600 return ret;
1601 }
1602
1603 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1604 struct extent_buffer *eb, void *ctx);
1605
1606 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1607 struct btrfs_path *path,
1608 iterate_irefs_t *iterate, void *ctx)
1609 {
1610 int ret = 0;
1611 int slot;
1612 u32 cur;
1613 u32 len;
1614 u32 name_len;
1615 u64 parent = 0;
1616 int found = 0;
1617 struct extent_buffer *eb;
1618 struct btrfs_item *item;
1619 struct btrfs_inode_ref *iref;
1620 struct btrfs_key found_key;
1621
1622 while (!ret) {
1623 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1624 &found_key);
1625 if (ret < 0)
1626 break;
1627 if (ret) {
1628 ret = found ? 0 : -ENOENT;
1629 break;
1630 }
1631 ++found;
1632
1633 parent = found_key.offset;
1634 slot = path->slots[0];
1635 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1636 if (!eb) {
1637 ret = -ENOMEM;
1638 break;
1639 }
1640 extent_buffer_get(eb);
1641 btrfs_tree_read_lock(eb);
1642 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1643 btrfs_release_path(path);
1644
1645 item = btrfs_item_nr(slot);
1646 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1647
1648 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1649 name_len = btrfs_inode_ref_name_len(eb, iref);
1650 /* path must be released before calling iterate()! */
1651 pr_debug("following ref at offset %u for inode %llu in "
1652 "tree %llu\n", cur, found_key.objectid,
1653 fs_root->objectid);
1654 ret = iterate(parent, name_len,
1655 (unsigned long)(iref + 1), eb, ctx);
1656 if (ret)
1657 break;
1658 len = sizeof(*iref) + name_len;
1659 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1660 }
1661 btrfs_tree_read_unlock_blocking(eb);
1662 free_extent_buffer(eb);
1663 }
1664
1665 btrfs_release_path(path);
1666
1667 return ret;
1668 }
1669
1670 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1671 struct btrfs_path *path,
1672 iterate_irefs_t *iterate, void *ctx)
1673 {
1674 int ret;
1675 int slot;
1676 u64 offset = 0;
1677 u64 parent;
1678 int found = 0;
1679 struct extent_buffer *eb;
1680 struct btrfs_inode_extref *extref;
1681 struct extent_buffer *leaf;
1682 u32 item_size;
1683 u32 cur_offset;
1684 unsigned long ptr;
1685
1686 while (1) {
1687 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1688 &offset);
1689 if (ret < 0)
1690 break;
1691 if (ret) {
1692 ret = found ? 0 : -ENOENT;
1693 break;
1694 }
1695 ++found;
1696
1697 slot = path->slots[0];
1698 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1699 if (!eb) {
1700 ret = -ENOMEM;
1701 break;
1702 }
1703 extent_buffer_get(eb);
1704
1705 btrfs_tree_read_lock(eb);
1706 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1707 btrfs_release_path(path);
1708
1709 leaf = path->nodes[0];
1710 item_size = btrfs_item_size_nr(leaf, slot);
1711 ptr = btrfs_item_ptr_offset(leaf, slot);
1712 cur_offset = 0;
1713
1714 while (cur_offset < item_size) {
1715 u32 name_len;
1716
1717 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1718 parent = btrfs_inode_extref_parent(eb, extref);
1719 name_len = btrfs_inode_extref_name_len(eb, extref);
1720 ret = iterate(parent, name_len,
1721 (unsigned long)&extref->name, eb, ctx);
1722 if (ret)
1723 break;
1724
1725 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1726 cur_offset += sizeof(*extref);
1727 }
1728 btrfs_tree_read_unlock_blocking(eb);
1729 free_extent_buffer(eb);
1730
1731 offset++;
1732 }
1733
1734 btrfs_release_path(path);
1735
1736 return ret;
1737 }
1738
1739 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1740 struct btrfs_path *path, iterate_irefs_t *iterate,
1741 void *ctx)
1742 {
1743 int ret;
1744 int found_refs = 0;
1745
1746 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1747 if (!ret)
1748 ++found_refs;
1749 else if (ret != -ENOENT)
1750 return ret;
1751
1752 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1753 if (ret == -ENOENT && found_refs)
1754 return 0;
1755
1756 return ret;
1757 }
1758
1759 /*
1760 * returns 0 if the path could be dumped (probably truncated)
1761 * returns <0 in case of an error
1762 */
1763 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1764 struct extent_buffer *eb, void *ctx)
1765 {
1766 struct inode_fs_paths *ipath = ctx;
1767 char *fspath;
1768 char *fspath_min;
1769 int i = ipath->fspath->elem_cnt;
1770 const int s_ptr = sizeof(char *);
1771 u32 bytes_left;
1772
1773 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1774 ipath->fspath->bytes_left - s_ptr : 0;
1775
1776 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1777 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1778 name_off, eb, inum, fspath_min, bytes_left);
1779 if (IS_ERR(fspath))
1780 return PTR_ERR(fspath);
1781
1782 if (fspath > fspath_min) {
1783 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1784 ++ipath->fspath->elem_cnt;
1785 ipath->fspath->bytes_left = fspath - fspath_min;
1786 } else {
1787 ++ipath->fspath->elem_missed;
1788 ipath->fspath->bytes_missing += fspath_min - fspath;
1789 ipath->fspath->bytes_left = 0;
1790 }
1791
1792 return 0;
1793 }
1794
1795 /*
1796 * this dumps all file system paths to the inode into the ipath struct, provided
1797 * is has been created large enough. each path is zero-terminated and accessed
1798 * from ipath->fspath->val[i].
1799 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1800 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1801 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1802 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1803 * have been needed to return all paths.
1804 */
1805 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1806 {
1807 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1808 inode_to_path, ipath);
1809 }
1810
1811 struct btrfs_data_container *init_data_container(u32 total_bytes)
1812 {
1813 struct btrfs_data_container *data;
1814 size_t alloc_bytes;
1815
1816 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1817 data = vmalloc(alloc_bytes);
1818 if (!data)
1819 return ERR_PTR(-ENOMEM);
1820
1821 if (total_bytes >= sizeof(*data)) {
1822 data->bytes_left = total_bytes - sizeof(*data);
1823 data->bytes_missing = 0;
1824 } else {
1825 data->bytes_missing = sizeof(*data) - total_bytes;
1826 data->bytes_left = 0;
1827 }
1828
1829 data->elem_cnt = 0;
1830 data->elem_missed = 0;
1831
1832 return data;
1833 }
1834
1835 /*
1836 * allocates space to return multiple file system paths for an inode.
1837 * total_bytes to allocate are passed, note that space usable for actual path
1838 * information will be total_bytes - sizeof(struct inode_fs_paths).
1839 * the returned pointer must be freed with free_ipath() in the end.
1840 */
1841 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1842 struct btrfs_path *path)
1843 {
1844 struct inode_fs_paths *ifp;
1845 struct btrfs_data_container *fspath;
1846
1847 fspath = init_data_container(total_bytes);
1848 if (IS_ERR(fspath))
1849 return (void *)fspath;
1850
1851 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1852 if (!ifp) {
1853 kfree(fspath);
1854 return ERR_PTR(-ENOMEM);
1855 }
1856
1857 ifp->btrfs_path = path;
1858 ifp->fspath = fspath;
1859 ifp->fs_root = fs_root;
1860
1861 return ifp;
1862 }
1863
1864 void free_ipath(struct inode_fs_paths *ipath)
1865 {
1866 if (!ipath)
1867 return;
1868 vfree(ipath->fspath);
1869 kfree(ipath);
1870 }
Linux with added FPC-III support