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Btrfs: fix backref walking when we hit a compressed extent
[deliverable/linux.git] / fs / btrfs / backref.c
1 /*
2 * Copyright (C) 2011 STRATO. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/vmalloc.h>
20 #include "ctree.h"
21 #include "disk-io.h"
22 #include "backref.h"
23 #include "ulist.h"
24 #include "transaction.h"
25 #include "delayed-ref.h"
26 #include "locking.h"
27
28 struct extent_inode_elem {
29 u64 inum;
30 u64 offset;
31 struct extent_inode_elem *next;
32 };
33
34 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
35 struct btrfs_file_extent_item *fi,
36 u64 extent_item_pos,
37 struct extent_inode_elem **eie)
38 {
39 u64 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 int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
70 u64 extent_item_pos,
71 struct extent_inode_elem **eie)
72 {
73 u64 disk_byte;
74 struct btrfs_key key;
75 struct btrfs_file_extent_item *fi;
76 int slot;
77 int nritems;
78 int extent_type;
79 int ret;
80
81 /*
82 * from the shared data ref, we only have the leaf but we need
83 * the key. thus, we must look into all items and see that we
84 * find one (some) with a reference to our extent item.
85 */
86 nritems = btrfs_header_nritems(eb);
87 for (slot = 0; slot < nritems; ++slot) {
88 btrfs_item_key_to_cpu(eb, &key, slot);
89 if (key.type != BTRFS_EXTENT_DATA_KEY)
90 continue;
91 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
92 extent_type = btrfs_file_extent_type(eb, fi);
93 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
94 continue;
95 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
96 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
97 if (disk_byte != wanted_disk_byte)
98 continue;
99
100 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
101 if (ret < 0)
102 return ret;
103 }
104
105 return 0;
106 }
107
108 /*
109 * this structure records all encountered refs on the way up to the root
110 */
111 struct __prelim_ref {
112 struct list_head list;
113 u64 root_id;
114 struct btrfs_key key_for_search;
115 int level;
116 int count;
117 struct extent_inode_elem *inode_list;
118 u64 parent;
119 u64 wanted_disk_byte;
120 };
121
122 /*
123 * the rules for all callers of this function are:
124 * - obtaining the parent is the goal
125 * - if you add a key, you must know that it is a correct key
126 * - if you cannot add the parent or a correct key, then we will look into the
127 * block later to set a correct key
128 *
129 * delayed refs
130 * ============
131 * backref type | shared | indirect | shared | indirect
132 * information | tree | tree | data | data
133 * --------------------+--------+----------+--------+----------
134 * parent logical | y | - | - | -
135 * key to resolve | - | y | y | y
136 * tree block logical | - | - | - | -
137 * root for resolving | y | y | y | y
138 *
139 * - column 1: we've the parent -> done
140 * - column 2, 3, 4: we use the key to find the parent
141 *
142 * on disk refs (inline or keyed)
143 * ==============================
144 * backref type | shared | indirect | shared | indirect
145 * information | tree | tree | data | data
146 * --------------------+--------+----------+--------+----------
147 * parent logical | y | - | y | -
148 * key to resolve | - | - | - | y
149 * tree block logical | y | y | y | y
150 * root for resolving | - | y | y | y
151 *
152 * - column 1, 3: we've the parent -> done
153 * - column 2: we take the first key from the block to find the parent
154 * (see __add_missing_keys)
155 * - column 4: we use the key to find the parent
156 *
157 * additional information that's available but not required to find the parent
158 * block might help in merging entries to gain some speed.
159 */
160
161 static int __add_prelim_ref(struct list_head *head, u64 root_id,
162 struct btrfs_key *key, int level,
163 u64 parent, u64 wanted_disk_byte, int count)
164 {
165 struct __prelim_ref *ref;
166
167 /* in case we're adding delayed refs, we're holding the refs spinlock */
168 ref = kmalloc(sizeof(*ref), GFP_ATOMIC);
169 if (!ref)
170 return -ENOMEM;
171
172 ref->root_id = root_id;
173 if (key)
174 ref->key_for_search = *key;
175 else
176 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
177
178 ref->inode_list = NULL;
179 ref->level = level;
180 ref->count = count;
181 ref->parent = parent;
182 ref->wanted_disk_byte = wanted_disk_byte;
183 list_add_tail(&ref->list, head);
184
185 return 0;
186 }
187
188 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
189 struct ulist *parents, int level,
190 struct btrfs_key *key_for_search, u64 time_seq,
191 u64 wanted_disk_byte,
192 const u64 *extent_item_pos)
193 {
194 int ret = 0;
195 int slot;
196 struct extent_buffer *eb;
197 struct btrfs_key key;
198 struct btrfs_file_extent_item *fi;
199 struct extent_inode_elem *eie = NULL;
200 u64 disk_byte;
201
202 if (level != 0) {
203 eb = path->nodes[level];
204 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
205 if (ret < 0)
206 return ret;
207 return 0;
208 }
209
210 /*
211 * We normally enter this function with the path already pointing to
212 * the first item to check. But sometimes, we may enter it with
213 * slot==nritems. In that case, go to the next leaf before we continue.
214 */
215 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
216 ret = btrfs_next_old_leaf(root, path, time_seq);
217
218 while (!ret) {
219 eb = path->nodes[0];
220 slot = path->slots[0];
221
222 btrfs_item_key_to_cpu(eb, &key, slot);
223
224 if (key.objectid != key_for_search->objectid ||
225 key.type != BTRFS_EXTENT_DATA_KEY)
226 break;
227
228 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
229 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
230
231 if (disk_byte == wanted_disk_byte) {
232 eie = NULL;
233 if (extent_item_pos) {
234 ret = check_extent_in_eb(&key, eb, fi,
235 *extent_item_pos,
236 &eie);
237 if (ret < 0)
238 break;
239 }
240 if (!ret) {
241 ret = ulist_add(parents, eb->start,
242 (uintptr_t)eie, GFP_NOFS);
243 if (ret < 0)
244 break;
245 if (!extent_item_pos) {
246 ret = btrfs_next_old_leaf(root, path,
247 time_seq);
248 continue;
249 }
250 }
251 }
252 ret = btrfs_next_old_item(root, path, time_seq);
253 }
254
255 if (ret > 0)
256 ret = 0;
257 return ret;
258 }
259
260 /*
261 * resolve an indirect backref in the form (root_id, key, level)
262 * to a logical address
263 */
264 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
265 struct btrfs_path *path, u64 time_seq,
266 struct __prelim_ref *ref,
267 struct ulist *parents,
268 const u64 *extent_item_pos)
269 {
270 struct btrfs_root *root;
271 struct btrfs_key root_key;
272 struct extent_buffer *eb;
273 int ret = 0;
274 int root_level;
275 int level = ref->level;
276
277 root_key.objectid = ref->root_id;
278 root_key.type = BTRFS_ROOT_ITEM_KEY;
279 root_key.offset = (u64)-1;
280 root = btrfs_read_fs_root_no_name(fs_info, &root_key);
281 if (IS_ERR(root)) {
282 ret = PTR_ERR(root);
283 goto out;
284 }
285
286 root_level = btrfs_old_root_level(root, time_seq);
287
288 if (root_level + 1 == level)
289 goto out;
290
291 path->lowest_level = level;
292 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
293 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
294 "%d for key (%llu %u %llu)\n",
295 (unsigned long long)ref->root_id, level, ref->count, ret,
296 (unsigned long long)ref->key_for_search.objectid,
297 ref->key_for_search.type,
298 (unsigned long long)ref->key_for_search.offset);
299 if (ret < 0)
300 goto out;
301
302 eb = path->nodes[level];
303 while (!eb) {
304 if (!level) {
305 WARN_ON(1);
306 ret = 1;
307 goto out;
308 }
309 level--;
310 eb = path->nodes[level];
311 }
312
313 ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
314 time_seq, ref->wanted_disk_byte,
315 extent_item_pos);
316 out:
317 path->lowest_level = 0;
318 btrfs_release_path(path);
319 return ret;
320 }
321
322 /*
323 * resolve all indirect backrefs from the list
324 */
325 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
326 struct btrfs_path *path, u64 time_seq,
327 struct list_head *head,
328 const u64 *extent_item_pos)
329 {
330 int err;
331 int ret = 0;
332 struct __prelim_ref *ref;
333 struct __prelim_ref *ref_safe;
334 struct __prelim_ref *new_ref;
335 struct ulist *parents;
336 struct ulist_node *node;
337 struct ulist_iterator uiter;
338
339 parents = ulist_alloc(GFP_NOFS);
340 if (!parents)
341 return -ENOMEM;
342
343 /*
344 * _safe allows us to insert directly after the current item without
345 * iterating over the newly inserted items.
346 * we're also allowed to re-assign ref during iteration.
347 */
348 list_for_each_entry_safe(ref, ref_safe, head, list) {
349 if (ref->parent) /* already direct */
350 continue;
351 if (ref->count == 0)
352 continue;
353 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
354 parents, extent_item_pos);
355 if (err == -ENOMEM)
356 goto out;
357 if (err)
358 continue;
359
360 /* we put the first parent into the ref at hand */
361 ULIST_ITER_INIT(&uiter);
362 node = ulist_next(parents, &uiter);
363 ref->parent = node ? node->val : 0;
364 ref->inode_list = node ?
365 (struct extent_inode_elem *)(uintptr_t)node->aux : 0;
366
367 /* additional parents require new refs being added here */
368 while ((node = ulist_next(parents, &uiter))) {
369 new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
370 if (!new_ref) {
371 ret = -ENOMEM;
372 goto out;
373 }
374 memcpy(new_ref, ref, sizeof(*ref));
375 new_ref->parent = node->val;
376 new_ref->inode_list = (struct extent_inode_elem *)
377 (uintptr_t)node->aux;
378 list_add(&new_ref->list, &ref->list);
379 }
380 ulist_reinit(parents);
381 }
382 out:
383 ulist_free(parents);
384 return ret;
385 }
386
387 static inline int ref_for_same_block(struct __prelim_ref *ref1,
388 struct __prelim_ref *ref2)
389 {
390 if (ref1->level != ref2->level)
391 return 0;
392 if (ref1->root_id != ref2->root_id)
393 return 0;
394 if (ref1->key_for_search.type != ref2->key_for_search.type)
395 return 0;
396 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
397 return 0;
398 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
399 return 0;
400 if (ref1->parent != ref2->parent)
401 return 0;
402
403 return 1;
404 }
405
406 /*
407 * read tree blocks and add keys where required.
408 */
409 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
410 struct list_head *head)
411 {
412 struct list_head *pos;
413 struct extent_buffer *eb;
414
415 list_for_each(pos, head) {
416 struct __prelim_ref *ref;
417 ref = list_entry(pos, struct __prelim_ref, list);
418
419 if (ref->parent)
420 continue;
421 if (ref->key_for_search.type)
422 continue;
423 BUG_ON(!ref->wanted_disk_byte);
424 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
425 fs_info->tree_root->leafsize, 0);
426 if (!eb || !extent_buffer_uptodate(eb)) {
427 free_extent_buffer(eb);
428 return -EIO;
429 }
430 btrfs_tree_read_lock(eb);
431 if (btrfs_header_level(eb) == 0)
432 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
433 else
434 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
435 btrfs_tree_read_unlock(eb);
436 free_extent_buffer(eb);
437 }
438 return 0;
439 }
440
441 /*
442 * merge two lists of backrefs and adjust counts accordingly
443 *
444 * mode = 1: merge identical keys, if key is set
445 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
446 * additionally, we could even add a key range for the blocks we
447 * looked into to merge even more (-> replace unresolved refs by those
448 * having a parent).
449 * mode = 2: merge identical parents
450 */
451 static void __merge_refs(struct list_head *head, int mode)
452 {
453 struct list_head *pos1;
454
455 list_for_each(pos1, head) {
456 struct list_head *n2;
457 struct list_head *pos2;
458 struct __prelim_ref *ref1;
459
460 ref1 = list_entry(pos1, struct __prelim_ref, list);
461
462 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
463 pos2 = n2, n2 = pos2->next) {
464 struct __prelim_ref *ref2;
465 struct __prelim_ref *xchg;
466 struct extent_inode_elem *eie;
467
468 ref2 = list_entry(pos2, struct __prelim_ref, list);
469
470 if (mode == 1) {
471 if (!ref_for_same_block(ref1, ref2))
472 continue;
473 if (!ref1->parent && ref2->parent) {
474 xchg = ref1;
475 ref1 = ref2;
476 ref2 = xchg;
477 }
478 } else {
479 if (ref1->parent != ref2->parent)
480 continue;
481 }
482
483 eie = ref1->inode_list;
484 while (eie && eie->next)
485 eie = eie->next;
486 if (eie)
487 eie->next = ref2->inode_list;
488 else
489 ref1->inode_list = ref2->inode_list;
490 ref1->count += ref2->count;
491
492 list_del(&ref2->list);
493 kfree(ref2);
494 }
495
496 }
497 }
498
499 /*
500 * add all currently queued delayed refs from this head whose seq nr is
501 * smaller or equal that seq to the list
502 */
503 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
504 struct list_head *prefs)
505 {
506 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
507 struct rb_node *n = &head->node.rb_node;
508 struct btrfs_key key;
509 struct btrfs_key op_key = {0};
510 int sgn;
511 int ret = 0;
512
513 if (extent_op && extent_op->update_key)
514 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
515
516 while ((n = rb_prev(n))) {
517 struct btrfs_delayed_ref_node *node;
518 node = rb_entry(n, struct btrfs_delayed_ref_node,
519 rb_node);
520 if (node->bytenr != head->node.bytenr)
521 break;
522 WARN_ON(node->is_head);
523
524 if (node->seq > seq)
525 continue;
526
527 switch (node->action) {
528 case BTRFS_ADD_DELAYED_EXTENT:
529 case BTRFS_UPDATE_DELAYED_HEAD:
530 WARN_ON(1);
531 continue;
532 case BTRFS_ADD_DELAYED_REF:
533 sgn = 1;
534 break;
535 case BTRFS_DROP_DELAYED_REF:
536 sgn = -1;
537 break;
538 default:
539 BUG_ON(1);
540 }
541 switch (node->type) {
542 case BTRFS_TREE_BLOCK_REF_KEY: {
543 struct btrfs_delayed_tree_ref *ref;
544
545 ref = btrfs_delayed_node_to_tree_ref(node);
546 ret = __add_prelim_ref(prefs, ref->root, &op_key,
547 ref->level + 1, 0, node->bytenr,
548 node->ref_mod * sgn);
549 break;
550 }
551 case BTRFS_SHARED_BLOCK_REF_KEY: {
552 struct btrfs_delayed_tree_ref *ref;
553
554 ref = btrfs_delayed_node_to_tree_ref(node);
555 ret = __add_prelim_ref(prefs, ref->root, NULL,
556 ref->level + 1, ref->parent,
557 node->bytenr,
558 node->ref_mod * sgn);
559 break;
560 }
561 case BTRFS_EXTENT_DATA_REF_KEY: {
562 struct btrfs_delayed_data_ref *ref;
563 ref = btrfs_delayed_node_to_data_ref(node);
564
565 key.objectid = ref->objectid;
566 key.type = BTRFS_EXTENT_DATA_KEY;
567 key.offset = ref->offset;
568 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
569 node->bytenr,
570 node->ref_mod * sgn);
571 break;
572 }
573 case BTRFS_SHARED_DATA_REF_KEY: {
574 struct btrfs_delayed_data_ref *ref;
575
576 ref = btrfs_delayed_node_to_data_ref(node);
577
578 key.objectid = ref->objectid;
579 key.type = BTRFS_EXTENT_DATA_KEY;
580 key.offset = ref->offset;
581 ret = __add_prelim_ref(prefs, ref->root, &key, 0,
582 ref->parent, node->bytenr,
583 node->ref_mod * sgn);
584 break;
585 }
586 default:
587 WARN_ON(1);
588 }
589 if (ret)
590 return ret;
591 }
592
593 return 0;
594 }
595
596 /*
597 * add all inline backrefs for bytenr to the list
598 */
599 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
600 struct btrfs_path *path, u64 bytenr,
601 int *info_level, struct list_head *prefs)
602 {
603 int ret = 0;
604 int slot;
605 struct extent_buffer *leaf;
606 struct btrfs_key key;
607 struct btrfs_key found_key;
608 unsigned long ptr;
609 unsigned long end;
610 struct btrfs_extent_item *ei;
611 u64 flags;
612 u64 item_size;
613
614 /*
615 * enumerate all inline refs
616 */
617 leaf = path->nodes[0];
618 slot = path->slots[0];
619
620 item_size = btrfs_item_size_nr(leaf, slot);
621 BUG_ON(item_size < sizeof(*ei));
622
623 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
624 flags = btrfs_extent_flags(leaf, ei);
625 btrfs_item_key_to_cpu(leaf, &found_key, slot);
626
627 ptr = (unsigned long)(ei + 1);
628 end = (unsigned long)ei + item_size;
629
630 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
631 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
632 struct btrfs_tree_block_info *info;
633
634 info = (struct btrfs_tree_block_info *)ptr;
635 *info_level = btrfs_tree_block_level(leaf, info);
636 ptr += sizeof(struct btrfs_tree_block_info);
637 BUG_ON(ptr > end);
638 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
639 *info_level = found_key.offset;
640 } else {
641 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
642 }
643
644 while (ptr < end) {
645 struct btrfs_extent_inline_ref *iref;
646 u64 offset;
647 int type;
648
649 iref = (struct btrfs_extent_inline_ref *)ptr;
650 type = btrfs_extent_inline_ref_type(leaf, iref);
651 offset = btrfs_extent_inline_ref_offset(leaf, iref);
652
653 switch (type) {
654 case BTRFS_SHARED_BLOCK_REF_KEY:
655 ret = __add_prelim_ref(prefs, 0, NULL,
656 *info_level + 1, offset,
657 bytenr, 1);
658 break;
659 case BTRFS_SHARED_DATA_REF_KEY: {
660 struct btrfs_shared_data_ref *sdref;
661 int count;
662
663 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
664 count = btrfs_shared_data_ref_count(leaf, sdref);
665 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
666 bytenr, count);
667 break;
668 }
669 case BTRFS_TREE_BLOCK_REF_KEY:
670 ret = __add_prelim_ref(prefs, offset, NULL,
671 *info_level + 1, 0,
672 bytenr, 1);
673 break;
674 case BTRFS_EXTENT_DATA_REF_KEY: {
675 struct btrfs_extent_data_ref *dref;
676 int count;
677 u64 root;
678
679 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
680 count = btrfs_extent_data_ref_count(leaf, dref);
681 key.objectid = btrfs_extent_data_ref_objectid(leaf,
682 dref);
683 key.type = BTRFS_EXTENT_DATA_KEY;
684 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
685 root = btrfs_extent_data_ref_root(leaf, dref);
686 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
687 bytenr, count);
688 break;
689 }
690 default:
691 WARN_ON(1);
692 }
693 if (ret)
694 return ret;
695 ptr += btrfs_extent_inline_ref_size(type);
696 }
697
698 return 0;
699 }
700
701 /*
702 * add all non-inline backrefs for bytenr to the list
703 */
704 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
705 struct btrfs_path *path, u64 bytenr,
706 int info_level, struct list_head *prefs)
707 {
708 struct btrfs_root *extent_root = fs_info->extent_root;
709 int ret;
710 int slot;
711 struct extent_buffer *leaf;
712 struct btrfs_key key;
713
714 while (1) {
715 ret = btrfs_next_item(extent_root, path);
716 if (ret < 0)
717 break;
718 if (ret) {
719 ret = 0;
720 break;
721 }
722
723 slot = path->slots[0];
724 leaf = path->nodes[0];
725 btrfs_item_key_to_cpu(leaf, &key, slot);
726
727 if (key.objectid != bytenr)
728 break;
729 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
730 continue;
731 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
732 break;
733
734 switch (key.type) {
735 case BTRFS_SHARED_BLOCK_REF_KEY:
736 ret = __add_prelim_ref(prefs, 0, NULL,
737 info_level + 1, key.offset,
738 bytenr, 1);
739 break;
740 case BTRFS_SHARED_DATA_REF_KEY: {
741 struct btrfs_shared_data_ref *sdref;
742 int count;
743
744 sdref = btrfs_item_ptr(leaf, slot,
745 struct btrfs_shared_data_ref);
746 count = btrfs_shared_data_ref_count(leaf, sdref);
747 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
748 bytenr, count);
749 break;
750 }
751 case BTRFS_TREE_BLOCK_REF_KEY:
752 ret = __add_prelim_ref(prefs, key.offset, NULL,
753 info_level + 1, 0,
754 bytenr, 1);
755 break;
756 case BTRFS_EXTENT_DATA_REF_KEY: {
757 struct btrfs_extent_data_ref *dref;
758 int count;
759 u64 root;
760
761 dref = btrfs_item_ptr(leaf, slot,
762 struct btrfs_extent_data_ref);
763 count = btrfs_extent_data_ref_count(leaf, dref);
764 key.objectid = btrfs_extent_data_ref_objectid(leaf,
765 dref);
766 key.type = BTRFS_EXTENT_DATA_KEY;
767 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
768 root = btrfs_extent_data_ref_root(leaf, dref);
769 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
770 bytenr, count);
771 break;
772 }
773 default:
774 WARN_ON(1);
775 }
776 if (ret)
777 return ret;
778
779 }
780
781 return ret;
782 }
783
784 /*
785 * this adds all existing backrefs (inline backrefs, backrefs and delayed
786 * refs) for the given bytenr to the refs list, merges duplicates and resolves
787 * indirect refs to their parent bytenr.
788 * When roots are found, they're added to the roots list
789 *
790 * FIXME some caching might speed things up
791 */
792 static int find_parent_nodes(struct btrfs_trans_handle *trans,
793 struct btrfs_fs_info *fs_info, u64 bytenr,
794 u64 time_seq, struct ulist *refs,
795 struct ulist *roots, const u64 *extent_item_pos)
796 {
797 struct btrfs_key key;
798 struct btrfs_path *path;
799 struct btrfs_delayed_ref_root *delayed_refs = NULL;
800 struct btrfs_delayed_ref_head *head;
801 int info_level = 0;
802 int ret;
803 struct list_head prefs_delayed;
804 struct list_head prefs;
805 struct __prelim_ref *ref;
806
807 INIT_LIST_HEAD(&prefs);
808 INIT_LIST_HEAD(&prefs_delayed);
809
810 key.objectid = bytenr;
811 key.offset = (u64)-1;
812 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
813 key.type = BTRFS_METADATA_ITEM_KEY;
814 else
815 key.type = BTRFS_EXTENT_ITEM_KEY;
816
817 path = btrfs_alloc_path();
818 if (!path)
819 return -ENOMEM;
820 if (!trans)
821 path->search_commit_root = 1;
822
823 /*
824 * grab both a lock on the path and a lock on the delayed ref head.
825 * We need both to get a consistent picture of how the refs look
826 * at a specified point in time
827 */
828 again:
829 head = NULL;
830
831 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
832 if (ret < 0)
833 goto out;
834 BUG_ON(ret == 0);
835
836 if (trans) {
837 /*
838 * look if there are updates for this ref queued and lock the
839 * head
840 */
841 delayed_refs = &trans->transaction->delayed_refs;
842 spin_lock(&delayed_refs->lock);
843 head = btrfs_find_delayed_ref_head(trans, bytenr);
844 if (head) {
845 if (!mutex_trylock(&head->mutex)) {
846 atomic_inc(&head->node.refs);
847 spin_unlock(&delayed_refs->lock);
848
849 btrfs_release_path(path);
850
851 /*
852 * Mutex was contended, block until it's
853 * released and try again
854 */
855 mutex_lock(&head->mutex);
856 mutex_unlock(&head->mutex);
857 btrfs_put_delayed_ref(&head->node);
858 goto again;
859 }
860 ret = __add_delayed_refs(head, time_seq,
861 &prefs_delayed);
862 mutex_unlock(&head->mutex);
863 if (ret) {
864 spin_unlock(&delayed_refs->lock);
865 goto out;
866 }
867 }
868 spin_unlock(&delayed_refs->lock);
869 }
870
871 if (path->slots[0]) {
872 struct extent_buffer *leaf;
873 int slot;
874
875 path->slots[0]--;
876 leaf = path->nodes[0];
877 slot = path->slots[0];
878 btrfs_item_key_to_cpu(leaf, &key, slot);
879 if (key.objectid == bytenr &&
880 (key.type == BTRFS_EXTENT_ITEM_KEY ||
881 key.type == BTRFS_METADATA_ITEM_KEY)) {
882 ret = __add_inline_refs(fs_info, path, bytenr,
883 &info_level, &prefs);
884 if (ret)
885 goto out;
886 ret = __add_keyed_refs(fs_info, path, bytenr,
887 info_level, &prefs);
888 if (ret)
889 goto out;
890 }
891 }
892 btrfs_release_path(path);
893
894 list_splice_init(&prefs_delayed, &prefs);
895
896 ret = __add_missing_keys(fs_info, &prefs);
897 if (ret)
898 goto out;
899
900 __merge_refs(&prefs, 1);
901
902 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
903 extent_item_pos);
904 if (ret)
905 goto out;
906
907 __merge_refs(&prefs, 2);
908
909 while (!list_empty(&prefs)) {
910 ref = list_first_entry(&prefs, struct __prelim_ref, list);
911 list_del(&ref->list);
912 WARN_ON(ref->count < 0);
913 if (ref->count && ref->root_id && ref->parent == 0) {
914 /* no parent == root of tree */
915 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
916 if (ret < 0)
917 goto out;
918 }
919 if (ref->count && ref->parent) {
920 struct extent_inode_elem *eie = NULL;
921 if (extent_item_pos && !ref->inode_list) {
922 u32 bsz;
923 struct extent_buffer *eb;
924 bsz = btrfs_level_size(fs_info->extent_root,
925 info_level);
926 eb = read_tree_block(fs_info->extent_root,
927 ref->parent, bsz, 0);
928 if (!eb || !extent_buffer_uptodate(eb)) {
929 free_extent_buffer(eb);
930 ret = -EIO;
931 goto out;
932 }
933 ret = find_extent_in_eb(eb, bytenr,
934 *extent_item_pos, &eie);
935 ref->inode_list = eie;
936 free_extent_buffer(eb);
937 }
938 ret = ulist_add_merge(refs, ref->parent,
939 (uintptr_t)ref->inode_list,
940 (u64 *)&eie, GFP_NOFS);
941 if (ret < 0)
942 goto out;
943 if (!ret && extent_item_pos) {
944 /*
945 * we've recorded that parent, so we must extend
946 * its inode list here
947 */
948 BUG_ON(!eie);
949 while (eie->next)
950 eie = eie->next;
951 eie->next = ref->inode_list;
952 }
953 }
954 kfree(ref);
955 }
956
957 out:
958 btrfs_free_path(path);
959 while (!list_empty(&prefs)) {
960 ref = list_first_entry(&prefs, struct __prelim_ref, list);
961 list_del(&ref->list);
962 kfree(ref);
963 }
964 while (!list_empty(&prefs_delayed)) {
965 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
966 list);
967 list_del(&ref->list);
968 kfree(ref);
969 }
970
971 return ret;
972 }
973
974 static void free_leaf_list(struct ulist *blocks)
975 {
976 struct ulist_node *node = NULL;
977 struct extent_inode_elem *eie;
978 struct extent_inode_elem *eie_next;
979 struct ulist_iterator uiter;
980
981 ULIST_ITER_INIT(&uiter);
982 while ((node = ulist_next(blocks, &uiter))) {
983 if (!node->aux)
984 continue;
985 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
986 for (; eie; eie = eie_next) {
987 eie_next = eie->next;
988 kfree(eie);
989 }
990 node->aux = 0;
991 }
992
993 ulist_free(blocks);
994 }
995
996 /*
997 * Finds all leafs with a reference to the specified combination of bytenr and
998 * offset. key_list_head will point to a list of corresponding keys (caller must
999 * free each list element). The leafs will be stored in the leafs ulist, which
1000 * must be freed with ulist_free.
1001 *
1002 * returns 0 on success, <0 on error
1003 */
1004 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1005 struct btrfs_fs_info *fs_info, u64 bytenr,
1006 u64 time_seq, struct ulist **leafs,
1007 const u64 *extent_item_pos)
1008 {
1009 struct ulist *tmp;
1010 int ret;
1011
1012 tmp = ulist_alloc(GFP_NOFS);
1013 if (!tmp)
1014 return -ENOMEM;
1015 *leafs = ulist_alloc(GFP_NOFS);
1016 if (!*leafs) {
1017 ulist_free(tmp);
1018 return -ENOMEM;
1019 }
1020
1021 ret = find_parent_nodes(trans, fs_info, bytenr,
1022 time_seq, *leafs, tmp, extent_item_pos);
1023 ulist_free(tmp);
1024
1025 if (ret < 0 && ret != -ENOENT) {
1026 free_leaf_list(*leafs);
1027 return ret;
1028 }
1029
1030 return 0;
1031 }
1032
1033 /*
1034 * walk all backrefs for a given extent to find all roots that reference this
1035 * extent. Walking a backref means finding all extents that reference this
1036 * extent and in turn walk the backrefs of those, too. Naturally this is a
1037 * recursive process, but here it is implemented in an iterative fashion: We
1038 * find all referencing extents for the extent in question and put them on a
1039 * list. In turn, we find all referencing extents for those, further appending
1040 * to the list. The way we iterate the list allows adding more elements after
1041 * the current while iterating. The process stops when we reach the end of the
1042 * list. Found roots are added to the roots list.
1043 *
1044 * returns 0 on success, < 0 on error.
1045 */
1046 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1047 struct btrfs_fs_info *fs_info, u64 bytenr,
1048 u64 time_seq, struct ulist **roots)
1049 {
1050 struct ulist *tmp;
1051 struct ulist_node *node = NULL;
1052 struct ulist_iterator uiter;
1053 int ret;
1054
1055 tmp = ulist_alloc(GFP_NOFS);
1056 if (!tmp)
1057 return -ENOMEM;
1058 *roots = ulist_alloc(GFP_NOFS);
1059 if (!*roots) {
1060 ulist_free(tmp);
1061 return -ENOMEM;
1062 }
1063
1064 ULIST_ITER_INIT(&uiter);
1065 while (1) {
1066 ret = find_parent_nodes(trans, fs_info, bytenr,
1067 time_seq, tmp, *roots, NULL);
1068 if (ret < 0 && ret != -ENOENT) {
1069 ulist_free(tmp);
1070 ulist_free(*roots);
1071 return ret;
1072 }
1073 node = ulist_next(tmp, &uiter);
1074 if (!node)
1075 break;
1076 bytenr = node->val;
1077 }
1078
1079 ulist_free(tmp);
1080 return 0;
1081 }
1082
1083
1084 static int __inode_info(u64 inum, u64 ioff, u8 key_type,
1085 struct btrfs_root *fs_root, struct btrfs_path *path,
1086 struct btrfs_key *found_key)
1087 {
1088 int ret;
1089 struct btrfs_key key;
1090 struct extent_buffer *eb;
1091
1092 key.type = key_type;
1093 key.objectid = inum;
1094 key.offset = ioff;
1095
1096 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1097 if (ret < 0)
1098 return ret;
1099
1100 eb = path->nodes[0];
1101 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1102 ret = btrfs_next_leaf(fs_root, path);
1103 if (ret)
1104 return ret;
1105 eb = path->nodes[0];
1106 }
1107
1108 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1109 if (found_key->type != key.type || found_key->objectid != key.objectid)
1110 return 1;
1111
1112 return 0;
1113 }
1114
1115 /*
1116 * this makes the path point to (inum INODE_ITEM ioff)
1117 */
1118 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1119 struct btrfs_path *path)
1120 {
1121 struct btrfs_key key;
1122 return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
1123 &key);
1124 }
1125
1126 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1127 struct btrfs_path *path,
1128 struct btrfs_key *found_key)
1129 {
1130 return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
1131 found_key);
1132 }
1133
1134 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1135 u64 start_off, struct btrfs_path *path,
1136 struct btrfs_inode_extref **ret_extref,
1137 u64 *found_off)
1138 {
1139 int ret, slot;
1140 struct btrfs_key key;
1141 struct btrfs_key found_key;
1142 struct btrfs_inode_extref *extref;
1143 struct extent_buffer *leaf;
1144 unsigned long ptr;
1145
1146 key.objectid = inode_objectid;
1147 btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1148 key.offset = start_off;
1149
1150 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1151 if (ret < 0)
1152 return ret;
1153
1154 while (1) {
1155 leaf = path->nodes[0];
1156 slot = path->slots[0];
1157 if (slot >= btrfs_header_nritems(leaf)) {
1158 /*
1159 * If the item at offset is not found,
1160 * btrfs_search_slot will point us to the slot
1161 * where it should be inserted. In our case
1162 * that will be the slot directly before the
1163 * next INODE_REF_KEY_V2 item. In the case
1164 * that we're pointing to the last slot in a
1165 * leaf, we must move one leaf over.
1166 */
1167 ret = btrfs_next_leaf(root, path);
1168 if (ret) {
1169 if (ret >= 1)
1170 ret = -ENOENT;
1171 break;
1172 }
1173 continue;
1174 }
1175
1176 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1177
1178 /*
1179 * Check that we're still looking at an extended ref key for
1180 * this particular objectid. If we have different
1181 * objectid or type then there are no more to be found
1182 * in the tree and we can exit.
1183 */
1184 ret = -ENOENT;
1185 if (found_key.objectid != inode_objectid)
1186 break;
1187 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1188 break;
1189
1190 ret = 0;
1191 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1192 extref = (struct btrfs_inode_extref *)ptr;
1193 *ret_extref = extref;
1194 if (found_off)
1195 *found_off = found_key.offset;
1196 break;
1197 }
1198
1199 return ret;
1200 }
1201
1202 /*
1203 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1204 * Elements of the path are separated by '/' and the path is guaranteed to be
1205 * 0-terminated. the path is only given within the current file system.
1206 * Therefore, it never starts with a '/'. the caller is responsible to provide
1207 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1208 * the start point of the resulting string is returned. this pointer is within
1209 * dest, normally.
1210 * in case the path buffer would overflow, the pointer is decremented further
1211 * as if output was written to the buffer, though no more output is actually
1212 * generated. that way, the caller can determine how much space would be
1213 * required for the path to fit into the buffer. in that case, the returned
1214 * value will be smaller than dest. callers must check this!
1215 */
1216 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1217 u32 name_len, unsigned long name_off,
1218 struct extent_buffer *eb_in, u64 parent,
1219 char *dest, u32 size)
1220 {
1221 int slot;
1222 u64 next_inum;
1223 int ret;
1224 s64 bytes_left = ((s64)size) - 1;
1225 struct extent_buffer *eb = eb_in;
1226 struct btrfs_key found_key;
1227 int leave_spinning = path->leave_spinning;
1228 struct btrfs_inode_ref *iref;
1229
1230 if (bytes_left >= 0)
1231 dest[bytes_left] = '\0';
1232
1233 path->leave_spinning = 1;
1234 while (1) {
1235 bytes_left -= name_len;
1236 if (bytes_left >= 0)
1237 read_extent_buffer(eb, dest + bytes_left,
1238 name_off, name_len);
1239 if (eb != eb_in) {
1240 btrfs_tree_read_unlock_blocking(eb);
1241 free_extent_buffer(eb);
1242 }
1243 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1244 if (ret > 0)
1245 ret = -ENOENT;
1246 if (ret)
1247 break;
1248
1249 next_inum = found_key.offset;
1250
1251 /* regular exit ahead */
1252 if (parent == next_inum)
1253 break;
1254
1255 slot = path->slots[0];
1256 eb = path->nodes[0];
1257 /* make sure we can use eb after releasing the path */
1258 if (eb != eb_in) {
1259 atomic_inc(&eb->refs);
1260 btrfs_tree_read_lock(eb);
1261 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1262 }
1263 btrfs_release_path(path);
1264 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1265
1266 name_len = btrfs_inode_ref_name_len(eb, iref);
1267 name_off = (unsigned long)(iref + 1);
1268
1269 parent = next_inum;
1270 --bytes_left;
1271 if (bytes_left >= 0)
1272 dest[bytes_left] = '/';
1273 }
1274
1275 btrfs_release_path(path);
1276 path->leave_spinning = leave_spinning;
1277
1278 if (ret)
1279 return ERR_PTR(ret);
1280
1281 return dest + bytes_left;
1282 }
1283
1284 /*
1285 * this makes the path point to (logical EXTENT_ITEM *)
1286 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1287 * tree blocks and <0 on error.
1288 */
1289 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1290 struct btrfs_path *path, struct btrfs_key *found_key,
1291 u64 *flags_ret)
1292 {
1293 int ret;
1294 u64 flags;
1295 u64 size = 0;
1296 u32 item_size;
1297 struct extent_buffer *eb;
1298 struct btrfs_extent_item *ei;
1299 struct btrfs_key key;
1300
1301 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1302 key.type = BTRFS_METADATA_ITEM_KEY;
1303 else
1304 key.type = BTRFS_EXTENT_ITEM_KEY;
1305 key.objectid = logical;
1306 key.offset = (u64)-1;
1307
1308 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1309 if (ret < 0)
1310 return ret;
1311 ret = btrfs_previous_item(fs_info->extent_root, path,
1312 0, BTRFS_EXTENT_ITEM_KEY);
1313 if (ret < 0)
1314 return ret;
1315
1316 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1317 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1318 size = fs_info->extent_root->leafsize;
1319 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1320 size = found_key->offset;
1321
1322 if ((found_key->type != BTRFS_EXTENT_ITEM_KEY &&
1323 found_key->type != BTRFS_METADATA_ITEM_KEY) ||
1324 found_key->objectid > logical ||
1325 found_key->objectid + size <= logical) {
1326 pr_debug("logical %llu is not within any extent\n",
1327 (unsigned long long)logical);
1328 return -ENOENT;
1329 }
1330
1331 eb = path->nodes[0];
1332 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1333 BUG_ON(item_size < sizeof(*ei));
1334
1335 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1336 flags = btrfs_extent_flags(eb, ei);
1337
1338 pr_debug("logical %llu is at position %llu within the extent (%llu "
1339 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1340 (unsigned long long)logical,
1341 (unsigned long long)(logical - found_key->objectid),
1342 (unsigned long long)found_key->objectid,
1343 (unsigned long long)found_key->offset,
1344 (unsigned long long)flags, item_size);
1345
1346 WARN_ON(!flags_ret);
1347 if (flags_ret) {
1348 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1349 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1350 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1351 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1352 else
1353 BUG_ON(1);
1354 return 0;
1355 }
1356
1357 return -EIO;
1358 }
1359
1360 /*
1361 * helper function to iterate extent inline refs. ptr must point to a 0 value
1362 * for the first call and may be modified. it is used to track state.
1363 * if more refs exist, 0 is returned and the next call to
1364 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1365 * next ref. after the last ref was processed, 1 is returned.
1366 * returns <0 on error
1367 */
1368 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1369 struct btrfs_extent_item *ei, u32 item_size,
1370 struct btrfs_extent_inline_ref **out_eiref,
1371 int *out_type)
1372 {
1373 unsigned long end;
1374 u64 flags;
1375 struct btrfs_tree_block_info *info;
1376
1377 if (!*ptr) {
1378 /* first call */
1379 flags = btrfs_extent_flags(eb, ei);
1380 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1381 info = (struct btrfs_tree_block_info *)(ei + 1);
1382 *out_eiref =
1383 (struct btrfs_extent_inline_ref *)(info + 1);
1384 } else {
1385 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1386 }
1387 *ptr = (unsigned long)*out_eiref;
1388 if ((void *)*ptr >= (void *)ei + item_size)
1389 return -ENOENT;
1390 }
1391
1392 end = (unsigned long)ei + item_size;
1393 *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1394 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1395
1396 *ptr += btrfs_extent_inline_ref_size(*out_type);
1397 WARN_ON(*ptr > end);
1398 if (*ptr == end)
1399 return 1; /* last */
1400
1401 return 0;
1402 }
1403
1404 /*
1405 * reads the tree block backref for an extent. tree level and root are returned
1406 * through out_level and out_root. ptr must point to a 0 value for the first
1407 * call and may be modified (see __get_extent_inline_ref comment).
1408 * returns 0 if data was provided, 1 if there was no more data to provide or
1409 * <0 on error.
1410 */
1411 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1412 struct btrfs_extent_item *ei, u32 item_size,
1413 u64 *out_root, u8 *out_level)
1414 {
1415 int ret;
1416 int type;
1417 struct btrfs_tree_block_info *info;
1418 struct btrfs_extent_inline_ref *eiref;
1419
1420 if (*ptr == (unsigned long)-1)
1421 return 1;
1422
1423 while (1) {
1424 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1425 &eiref, &type);
1426 if (ret < 0)
1427 return ret;
1428
1429 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1430 type == BTRFS_SHARED_BLOCK_REF_KEY)
1431 break;
1432
1433 if (ret == 1)
1434 return 1;
1435 }
1436
1437 /* we can treat both ref types equally here */
1438 info = (struct btrfs_tree_block_info *)(ei + 1);
1439 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1440 *out_level = btrfs_tree_block_level(eb, info);
1441
1442 if (ret == 1)
1443 *ptr = (unsigned long)-1;
1444
1445 return 0;
1446 }
1447
1448 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1449 u64 root, u64 extent_item_objectid,
1450 iterate_extent_inodes_t *iterate, void *ctx)
1451 {
1452 struct extent_inode_elem *eie;
1453 int ret = 0;
1454
1455 for (eie = inode_list; eie; eie = eie->next) {
1456 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1457 "root %llu\n", extent_item_objectid,
1458 eie->inum, eie->offset, root);
1459 ret = iterate(eie->inum, eie->offset, root, ctx);
1460 if (ret) {
1461 pr_debug("stopping iteration for %llu due to ret=%d\n",
1462 extent_item_objectid, ret);
1463 break;
1464 }
1465 }
1466
1467 return ret;
1468 }
1469
1470 /*
1471 * calls iterate() for every inode that references the extent identified by
1472 * the given parameters.
1473 * when the iterator function returns a non-zero value, iteration stops.
1474 */
1475 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1476 u64 extent_item_objectid, u64 extent_item_pos,
1477 int search_commit_root,
1478 iterate_extent_inodes_t *iterate, void *ctx)
1479 {
1480 int ret;
1481 struct btrfs_trans_handle *trans = NULL;
1482 struct ulist *refs = NULL;
1483 struct ulist *roots = NULL;
1484 struct ulist_node *ref_node = NULL;
1485 struct ulist_node *root_node = NULL;
1486 struct seq_list tree_mod_seq_elem = {};
1487 struct ulist_iterator ref_uiter;
1488 struct ulist_iterator root_uiter;
1489
1490 pr_debug("resolving all inodes for extent %llu\n",
1491 extent_item_objectid);
1492
1493 if (!search_commit_root) {
1494 trans = btrfs_join_transaction(fs_info->extent_root);
1495 if (IS_ERR(trans))
1496 return PTR_ERR(trans);
1497 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1498 }
1499
1500 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1501 tree_mod_seq_elem.seq, &refs,
1502 &extent_item_pos);
1503 if (ret)
1504 goto out;
1505
1506 ULIST_ITER_INIT(&ref_uiter);
1507 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1508 ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
1509 tree_mod_seq_elem.seq, &roots);
1510 if (ret)
1511 break;
1512 ULIST_ITER_INIT(&root_uiter);
1513 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1514 pr_debug("root %llu references leaf %llu, data list "
1515 "%#llx\n", root_node->val, ref_node->val,
1516 (long long)ref_node->aux);
1517 ret = iterate_leaf_refs((struct extent_inode_elem *)
1518 (uintptr_t)ref_node->aux,
1519 root_node->val,
1520 extent_item_objectid,
1521 iterate, ctx);
1522 }
1523 ulist_free(roots);
1524 }
1525
1526 free_leaf_list(refs);
1527 out:
1528 if (!search_commit_root) {
1529 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1530 btrfs_end_transaction(trans, fs_info->extent_root);
1531 }
1532
1533 return ret;
1534 }
1535
1536 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1537 struct btrfs_path *path,
1538 iterate_extent_inodes_t *iterate, void *ctx)
1539 {
1540 int ret;
1541 u64 extent_item_pos;
1542 u64 flags = 0;
1543 struct btrfs_key found_key;
1544 int search_commit_root = path->search_commit_root;
1545
1546 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1547 btrfs_release_path(path);
1548 if (ret < 0)
1549 return ret;
1550 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1551 return -EINVAL;
1552
1553 extent_item_pos = logical - found_key.objectid;
1554 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1555 extent_item_pos, search_commit_root,
1556 iterate, ctx);
1557
1558 return ret;
1559 }
1560
1561 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1562 struct extent_buffer *eb, void *ctx);
1563
1564 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1565 struct btrfs_path *path,
1566 iterate_irefs_t *iterate, void *ctx)
1567 {
1568 int ret = 0;
1569 int slot;
1570 u32 cur;
1571 u32 len;
1572 u32 name_len;
1573 u64 parent = 0;
1574 int found = 0;
1575 struct extent_buffer *eb;
1576 struct btrfs_item *item;
1577 struct btrfs_inode_ref *iref;
1578 struct btrfs_key found_key;
1579
1580 while (!ret) {
1581 path->leave_spinning = 1;
1582 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1583 &found_key);
1584 if (ret < 0)
1585 break;
1586 if (ret) {
1587 ret = found ? 0 : -ENOENT;
1588 break;
1589 }
1590 ++found;
1591
1592 parent = found_key.offset;
1593 slot = path->slots[0];
1594 eb = path->nodes[0];
1595 /* make sure we can use eb after releasing the path */
1596 atomic_inc(&eb->refs);
1597 btrfs_tree_read_lock(eb);
1598 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1599 btrfs_release_path(path);
1600
1601 item = btrfs_item_nr(eb, slot);
1602 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1603
1604 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1605 name_len = btrfs_inode_ref_name_len(eb, iref);
1606 /* path must be released before calling iterate()! */
1607 pr_debug("following ref at offset %u for inode %llu in "
1608 "tree %llu\n", cur,
1609 (unsigned long long)found_key.objectid,
1610 (unsigned long long)fs_root->objectid);
1611 ret = iterate(parent, name_len,
1612 (unsigned long)(iref + 1), eb, ctx);
1613 if (ret)
1614 break;
1615 len = sizeof(*iref) + name_len;
1616 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1617 }
1618 btrfs_tree_read_unlock_blocking(eb);
1619 free_extent_buffer(eb);
1620 }
1621
1622 btrfs_release_path(path);
1623
1624 return ret;
1625 }
1626
1627 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1628 struct btrfs_path *path,
1629 iterate_irefs_t *iterate, void *ctx)
1630 {
1631 int ret;
1632 int slot;
1633 u64 offset = 0;
1634 u64 parent;
1635 int found = 0;
1636 struct extent_buffer *eb;
1637 struct btrfs_inode_extref *extref;
1638 struct extent_buffer *leaf;
1639 u32 item_size;
1640 u32 cur_offset;
1641 unsigned long ptr;
1642
1643 while (1) {
1644 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1645 &offset);
1646 if (ret < 0)
1647 break;
1648 if (ret) {
1649 ret = found ? 0 : -ENOENT;
1650 break;
1651 }
1652 ++found;
1653
1654 slot = path->slots[0];
1655 eb = path->nodes[0];
1656 /* make sure we can use eb after releasing the path */
1657 atomic_inc(&eb->refs);
1658
1659 btrfs_tree_read_lock(eb);
1660 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1661 btrfs_release_path(path);
1662
1663 leaf = path->nodes[0];
1664 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1665 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1666 cur_offset = 0;
1667
1668 while (cur_offset < item_size) {
1669 u32 name_len;
1670
1671 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1672 parent = btrfs_inode_extref_parent(eb, extref);
1673 name_len = btrfs_inode_extref_name_len(eb, extref);
1674 ret = iterate(parent, name_len,
1675 (unsigned long)&extref->name, eb, ctx);
1676 if (ret)
1677 break;
1678
1679 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1680 cur_offset += sizeof(*extref);
1681 }
1682 btrfs_tree_read_unlock_blocking(eb);
1683 free_extent_buffer(eb);
1684
1685 offset++;
1686 }
1687
1688 btrfs_release_path(path);
1689
1690 return ret;
1691 }
1692
1693 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1694 struct btrfs_path *path, iterate_irefs_t *iterate,
1695 void *ctx)
1696 {
1697 int ret;
1698 int found_refs = 0;
1699
1700 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1701 if (!ret)
1702 ++found_refs;
1703 else if (ret != -ENOENT)
1704 return ret;
1705
1706 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1707 if (ret == -ENOENT && found_refs)
1708 return 0;
1709
1710 return ret;
1711 }
1712
1713 /*
1714 * returns 0 if the path could be dumped (probably truncated)
1715 * returns <0 in case of an error
1716 */
1717 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1718 struct extent_buffer *eb, void *ctx)
1719 {
1720 struct inode_fs_paths *ipath = ctx;
1721 char *fspath;
1722 char *fspath_min;
1723 int i = ipath->fspath->elem_cnt;
1724 const int s_ptr = sizeof(char *);
1725 u32 bytes_left;
1726
1727 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1728 ipath->fspath->bytes_left - s_ptr : 0;
1729
1730 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1731 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1732 name_off, eb, inum, fspath_min, bytes_left);
1733 if (IS_ERR(fspath))
1734 return PTR_ERR(fspath);
1735
1736 if (fspath > fspath_min) {
1737 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1738 ++ipath->fspath->elem_cnt;
1739 ipath->fspath->bytes_left = fspath - fspath_min;
1740 } else {
1741 ++ipath->fspath->elem_missed;
1742 ipath->fspath->bytes_missing += fspath_min - fspath;
1743 ipath->fspath->bytes_left = 0;
1744 }
1745
1746 return 0;
1747 }
1748
1749 /*
1750 * this dumps all file system paths to the inode into the ipath struct, provided
1751 * is has been created large enough. each path is zero-terminated and accessed
1752 * from ipath->fspath->val[i].
1753 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1754 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1755 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1756 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1757 * have been needed to return all paths.
1758 */
1759 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1760 {
1761 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1762 inode_to_path, ipath);
1763 }
1764
1765 struct btrfs_data_container *init_data_container(u32 total_bytes)
1766 {
1767 struct btrfs_data_container *data;
1768 size_t alloc_bytes;
1769
1770 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1771 data = vmalloc(alloc_bytes);
1772 if (!data)
1773 return ERR_PTR(-ENOMEM);
1774
1775 if (total_bytes >= sizeof(*data)) {
1776 data->bytes_left = total_bytes - sizeof(*data);
1777 data->bytes_missing = 0;
1778 } else {
1779 data->bytes_missing = sizeof(*data) - total_bytes;
1780 data->bytes_left = 0;
1781 }
1782
1783 data->elem_cnt = 0;
1784 data->elem_missed = 0;
1785
1786 return data;
1787 }
1788
1789 /*
1790 * allocates space to return multiple file system paths for an inode.
1791 * total_bytes to allocate are passed, note that space usable for actual path
1792 * information will be total_bytes - sizeof(struct inode_fs_paths).
1793 * the returned pointer must be freed with free_ipath() in the end.
1794 */
1795 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1796 struct btrfs_path *path)
1797 {
1798 struct inode_fs_paths *ifp;
1799 struct btrfs_data_container *fspath;
1800
1801 fspath = init_data_container(total_bytes);
1802 if (IS_ERR(fspath))
1803 return (void *)fspath;
1804
1805 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1806 if (!ifp) {
1807 kfree(fspath);
1808 return ERR_PTR(-ENOMEM);
1809 }
1810
1811 ifp->btrfs_path = path;
1812 ifp->fspath = fspath;
1813 ifp->fs_root = fs_root;
1814
1815 return ifp;
1816 }
1817
1818 void free_ipath(struct inode_fs_paths *ipath)
1819 {
1820 if (!ipath)
1821 return;
1822 vfree(ipath->fspath);
1823 kfree(ipath);
1824 }
Linux kernel - Deliverables
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