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Btrfs progs v4.13.1
[btrfs-progs-unstable/devel.git] / backref.c
blobafd14235d6fc8862571a286c500435f1b34bc2aa
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 "kerncompat.h"
20 #include "ctree.h"
21 #include "disk-io.h"
22 #include "backref.h"
23 #include "kernel-shared/ulist.h"
24 #include "transaction.h"
25 #include "internal.h"
26
27 #define pr_debug(...) do { } while (0)
28
29 struct extent_inode_elem {
30 u64 inum;
31 u64 offset;
32 struct extent_inode_elem *next;
33 };
34
35 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
36 struct btrfs_file_extent_item *fi,
37 u64 extent_item_pos,
38 struct extent_inode_elem **eie)
39 {
40 u64 offset = 0;
41 struct extent_inode_elem *e;
42
43 if (!btrfs_file_extent_compression(eb, fi) &&
44 !btrfs_file_extent_encryption(eb, fi) &&
45 !btrfs_file_extent_other_encoding(eb, fi)) {
46 u64 data_offset;
47 u64 data_len;
48
49 data_offset = btrfs_file_extent_offset(eb, fi);
50 data_len = btrfs_file_extent_num_bytes(eb, fi);
51
52 if (extent_item_pos < data_offset ||
53 extent_item_pos >= data_offset + data_len)
54 return 1;
55 offset = extent_item_pos - data_offset;
56 }
57
58 e = kmalloc(sizeof(*e), GFP_NOFS);
59 if (!e)
60 return -ENOMEM;
61
62 e->next = *eie;
63 e->inum = key->objectid;
64 e->offset = key->offset + offset;
65 *eie = e;
66
67 return 0;
68 }
69
70 static void free_inode_elem_list(struct extent_inode_elem *eie)
71 {
72 struct extent_inode_elem *eie_next;
73
74 for (; eie; eie = eie_next) {
75 eie_next = eie->next;
76 kfree(eie);
77 }
78 }
79
80 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
81 u64 extent_item_pos,
82 struct extent_inode_elem **eie)
83 {
84 u64 disk_byte;
85 struct btrfs_key key;
86 struct btrfs_file_extent_item *fi;
87 int slot;
88 int nritems;
89 int extent_type;
90 int ret;
91
92 /*
93 * from the shared data ref, we only have the leaf but we need
94 * the key. thus, we must look into all items and see that we
95 * find one (some) with a reference to our extent item.
96 */
97 nritems = btrfs_header_nritems(eb);
98 for (slot = 0; slot < nritems; ++slot) {
99 btrfs_item_key_to_cpu(eb, &key, slot);
100 if (key.type != BTRFS_EXTENT_DATA_KEY)
101 continue;
102 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
103 extent_type = btrfs_file_extent_type(eb, fi);
104 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
105 continue;
106 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
107 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
108 if (disk_byte != wanted_disk_byte)
109 continue;
110
111 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
112 if (ret < 0)
113 return ret;
114 }
115
116 return 0;
117 }
118
119 /*
120 * this structure records all encountered refs on the way up to the root
121 */
122 struct __prelim_ref {
123 struct list_head list;
124 u64 root_id;
125 struct btrfs_key key_for_search;
126 int level;
127 int count;
128 struct extent_inode_elem *inode_list;
129 u64 parent;
130 u64 wanted_disk_byte;
131 };
132
133 /*
134 * the rules for all callers of this function are:
135 * - obtaining the parent is the goal
136 * - if you add a key, you must know that it is a correct key
137 * - if you cannot add the parent or a correct key, then we will look into the
138 * block later to set a correct key
139 *
140 * delayed refs
141 * ============
142 * backref type | shared | indirect | shared | indirect
143 * information | tree | tree | data | data
144 * --------------------+--------+----------+--------+----------
145 * parent logical | y | - | - | -
146 * key to resolve | - | y | y | y
147 * tree block logical | - | - | - | -
148 * root for resolving | y | y | y | y
149 *
150 * - column 1: we've the parent -> done
151 * - column 2, 3, 4: we use the key to find the parent
152 *
153 * on disk refs (inline or keyed)
154 * ==============================
155 * backref type | shared | indirect | shared | indirect
156 * information | tree | tree | data | data
157 * --------------------+--------+----------+--------+----------
158 * parent logical | y | - | y | -
159 * key to resolve | - | - | - | y
160 * tree block logical | y | y | y | y
161 * root for resolving | - | y | y | y
162 *
163 * - column 1, 3: we've the parent -> done
164 * - column 2: we take the first key from the block to find the parent
165 * (see __add_missing_keys)
166 * - column 4: we use the key to find the parent
167 *
168 * additional information that's available but not required to find the parent
169 * block might help in merging entries to gain some speed.
170 */
171
172 static int __add_prelim_ref(struct list_head *head, u64 root_id,
173 struct btrfs_key *key, int level,
174 u64 parent, u64 wanted_disk_byte, int count,
175 gfp_t gfp_mask)
176 {
177 struct __prelim_ref *ref;
178
179 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
180 return 0;
181
182 ref = kmalloc(sizeof(*ref), gfp_mask);
183 if (!ref)
184 return -ENOMEM;
185
186 ref->root_id = root_id;
187 if (key)
188 ref->key_for_search = *key;
189 else
190 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
191
192 ref->inode_list = NULL;
193 ref->level = level;
194 ref->count = count;
195 ref->parent = parent;
196 ref->wanted_disk_byte = wanted_disk_byte;
197 list_add_tail(&ref->list, head);
198
199 return 0;
200 }
201
202 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
203 struct ulist *parents, struct __prelim_ref *ref,
204 int level, u64 time_seq, const u64 *extent_item_pos,
205 u64 total_refs)
206 {
207 int ret = 0;
208 int slot;
209 struct extent_buffer *eb;
210 struct btrfs_key key;
211 struct btrfs_key *key_for_search = &ref->key_for_search;
212 struct btrfs_file_extent_item *fi;
213 struct extent_inode_elem *eie = NULL, *old = NULL;
214 u64 disk_byte;
215 u64 wanted_disk_byte = ref->wanted_disk_byte;
216 u64 count = 0;
217
218 if (level != 0) {
219 eb = path->nodes[level];
220 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
221 if (ret < 0)
222 return ret;
223 return 0;
224 }
225
226 /*
227 * We normally enter this function with the path already pointing to
228 * the first item to check. But sometimes, we may enter it with
229 * slot==nritems. In that case, go to the next leaf before we continue.
230 */
231 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
232 ret = btrfs_next_leaf(root, path);
233
234 while (!ret && count < total_refs) {
235 eb = path->nodes[0];
236 slot = path->slots[0];
237
238 btrfs_item_key_to_cpu(eb, &key, slot);
239
240 if (key.objectid != key_for_search->objectid ||
241 key.type != BTRFS_EXTENT_DATA_KEY)
242 break;
243
244 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
245 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
246
247 if (disk_byte == wanted_disk_byte) {
248 eie = NULL;
249 old = NULL;
250 count++;
251 if (extent_item_pos) {
252 ret = check_extent_in_eb(&key, eb, fi,
253 *extent_item_pos,
254 &eie);
255 if (ret < 0)
256 break;
257 }
258 if (ret > 0)
259 goto next;
260 ret = ulist_add_merge_ptr(parents, eb->start,
261 eie, (void **)&old, GFP_NOFS);
262 if (ret < 0)
263 break;
264 if (!ret && extent_item_pos) {
265 while (old->next)
266 old = old->next;
267 old->next = eie;
268 }
269 eie = NULL;
270 }
271 next:
272 ret = btrfs_next_item(root, path);
273 }
274
275 if (ret > 0)
276 ret = 0;
277 else if (ret < 0)
278 free_inode_elem_list(eie);
279 return ret;
280 }
281
282 /*
283 * resolve an indirect backref in the form (root_id, key, level)
284 * to a logical address
285 */
286 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
287 struct btrfs_path *path, u64 time_seq,
288 struct __prelim_ref *ref,
289 struct ulist *parents,
290 const u64 *extent_item_pos, u64 total_refs)
291 {
292 struct btrfs_root *root;
293 struct btrfs_key root_key;
294 struct extent_buffer *eb;
295 int ret = 0;
296 int root_level;
297 int level = ref->level;
298
299 root_key.objectid = ref->root_id;
300 root_key.type = BTRFS_ROOT_ITEM_KEY;
301 root_key.offset = (u64)-1;
302
303 root = btrfs_read_fs_root(fs_info, &root_key);
304 if (IS_ERR(root)) {
305 ret = PTR_ERR(root);
306 goto out;
307 }
308
309 root_level = btrfs_root_level(&root->root_item);
310
311 if (root_level + 1 == level)
312 goto out;
313
314 path->lowest_level = level;
315 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path, 0, 0);
316
317 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
318 "%d for key (%llu %u %llu)\n",
319 ref->root_id, level, ref->count, ret,
320 ref->key_for_search.objectid, ref->key_for_search.type,
321 ref->key_for_search.offset);
322 if (ret < 0)
323 goto out;
324
325 eb = path->nodes[level];
326 while (!eb) {
327 if (!level) {
328 ret = 1;
329 WARN_ON(1);
330 goto out;
331 }
332 level--;
333 eb = path->nodes[level];
334 }
335
336 ret = add_all_parents(root, path, parents, ref, level, time_seq,
337 extent_item_pos, total_refs);
338 out:
339 path->lowest_level = 0;
340 btrfs_release_path(path);
341 return ret;
342 }
343
344 /*
345 * resolve all indirect backrefs from the list
346 */
347 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
348 struct btrfs_path *path, u64 time_seq,
349 struct list_head *head,
350 const u64 *extent_item_pos, u64 total_refs)
351 {
352 int err;
353 int ret = 0;
354 struct __prelim_ref *ref;
355 struct __prelim_ref *ref_safe;
356 struct __prelim_ref *new_ref;
357 struct ulist *parents;
358 struct ulist_node *node;
359 struct ulist_iterator uiter;
360
361 parents = ulist_alloc(GFP_NOFS);
362 if (!parents)
363 return -ENOMEM;
364
365 /*
366 * _safe allows us to insert directly after the current item without
367 * iterating over the newly inserted items.
368 * we're also allowed to re-assign ref during iteration.
369 */
370 list_for_each_entry_safe(ref, ref_safe, head, list) {
371 if (ref->parent) /* already direct */
372 continue;
373 if (ref->count == 0)
374 continue;
375 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
376 parents, extent_item_pos,
377 total_refs);
378 /*
379 * we can only tolerate ENOENT,otherwise,we should catch error
380 * and return directly.
381 */
382 if (err == -ENOENT) {
383 continue;
384 } else if (err) {
385 ret = err;
386 goto out;
387 }
388
389 /* we put the first parent into the ref at hand */
390 ULIST_ITER_INIT(&uiter);
391 node = ulist_next(parents, &uiter);
392 ref->parent = node ? node->val : 0;
393 ref->inode_list = node ?
394 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
395
396 /* additional parents require new refs being added here */
397 while ((node = ulist_next(parents, &uiter))) {
398 new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
399 if (!new_ref) {
400 ret = -ENOMEM;
401 goto out;
402 }
403 memcpy(new_ref, ref, sizeof(*ref));
404 new_ref->parent = node->val;
405 new_ref->inode_list = (struct extent_inode_elem *)
406 (uintptr_t)node->aux;
407 list_add(&new_ref->list, &ref->list);
408 }
409 ulist_reinit(parents);
410 }
411 out:
412 ulist_free(parents);
413 return ret;
414 }
415
416 static inline int ref_for_same_block(struct __prelim_ref *ref1,
417 struct __prelim_ref *ref2)
418 {
419 if (ref1->level != ref2->level)
420 return 0;
421 if (ref1->root_id != ref2->root_id)
422 return 0;
423 if (ref1->key_for_search.type != ref2->key_for_search.type)
424 return 0;
425 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
426 return 0;
427 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
428 return 0;
429 if (ref1->parent != ref2->parent)
430 return 0;
431
432 return 1;
433 }
434
435 /*
436 * read tree blocks and add keys where required.
437 */
438 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
439 struct list_head *head)
440 {
441 struct list_head *pos;
442 struct extent_buffer *eb;
443
444 list_for_each(pos, head) {
445 struct __prelim_ref *ref;
446 ref = list_entry(pos, struct __prelim_ref, list);
447
448 if (ref->parent)
449 continue;
450 if (ref->key_for_search.type)
451 continue;
452 BUG_ON(!ref->wanted_disk_byte);
453 eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0);
454 if (!extent_buffer_uptodate(eb)) {
455 free_extent_buffer(eb);
456 return -EIO;
457 }
458 if (btrfs_header_level(eb) == 0)
459 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
460 else
461 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
462 free_extent_buffer(eb);
463 }
464 return 0;
465 }
466
467 /*
468 * merge two lists of backrefs and adjust counts accordingly
469 *
470 * mode = 1: merge identical keys, if key is set
471 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
472 * additionally, we could even add a key range for the blocks we
473 * looked into to merge even more (-> replace unresolved refs by those
474 * having a parent).
475 * mode = 2: merge identical parents
476 */
477 static void __merge_refs(struct list_head *head, int mode)
478 {
479 struct list_head *pos1;
480
481 list_for_each(pos1, head) {
482 struct list_head *n2;
483 struct list_head *pos2;
484 struct __prelim_ref *ref1;
485
486 ref1 = list_entry(pos1, struct __prelim_ref, list);
487
488 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
489 pos2 = n2, n2 = pos2->next) {
490 struct __prelim_ref *ref2;
491 struct __prelim_ref *xchg;
492 struct extent_inode_elem *eie;
493
494 ref2 = list_entry(pos2, struct __prelim_ref, list);
495
496 if (mode == 1) {
497 if (!ref_for_same_block(ref1, ref2))
498 continue;
499 if (!ref1->parent && ref2->parent) {
500 xchg = ref1;
501 ref1 = ref2;
502 ref2 = xchg;
503 }
504 } else {
505 if (ref1->parent != ref2->parent)
506 continue;
507 }
508
509 eie = ref1->inode_list;
510 while (eie && eie->next)
511 eie = eie->next;
512 if (eie)
513 eie->next = ref2->inode_list;
514 else
515 ref1->inode_list = ref2->inode_list;
516 ref1->count += ref2->count;
517
518 list_del(&ref2->list);
519 kfree(ref2);
520 }
521
522 }
523 }
524
525 /*
526 * add all inline backrefs for bytenr to the list
527 */
528 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
529 struct btrfs_path *path, u64 bytenr,
530 int *info_level, struct list_head *prefs,
531 u64 *total_refs)
532 {
533 int ret = 0;
534 int slot;
535 struct extent_buffer *leaf;
536 struct btrfs_key key;
537 struct btrfs_key found_key;
538 unsigned long ptr;
539 unsigned long end;
540 struct btrfs_extent_item *ei;
541 u64 flags;
542 u64 item_size;
543
544 /*
545 * enumerate all inline refs
546 */
547 leaf = path->nodes[0];
548 slot = path->slots[0];
549
550 item_size = btrfs_item_size_nr(leaf, slot);
551 BUG_ON(item_size < sizeof(*ei));
552
553 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
554 flags = btrfs_extent_flags(leaf, ei);
555 *total_refs += btrfs_extent_refs(leaf, ei);
556 btrfs_item_key_to_cpu(leaf, &found_key, slot);
557
558 ptr = (unsigned long)(ei + 1);
559 end = (unsigned long)ei + item_size;
560
561 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
562 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
563 struct btrfs_tree_block_info *info;
564
565 info = (struct btrfs_tree_block_info *)ptr;
566 *info_level = btrfs_tree_block_level(leaf, info);
567 ptr += sizeof(struct btrfs_tree_block_info);
568 BUG_ON(ptr > end);
569 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
570 *info_level = found_key.offset;
571 } else {
572 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
573 }
574
575 while (ptr < end) {
576 struct btrfs_extent_inline_ref *iref;
577 u64 offset;
578 int type;
579
580 iref = (struct btrfs_extent_inline_ref *)ptr;
581 type = btrfs_extent_inline_ref_type(leaf, iref);
582 offset = btrfs_extent_inline_ref_offset(leaf, iref);
583
584 switch (type) {
585 case BTRFS_SHARED_BLOCK_REF_KEY:
586 ret = __add_prelim_ref(prefs, 0, NULL,
587 *info_level + 1, offset,
588 bytenr, 1, GFP_NOFS);
589 break;
590 case BTRFS_SHARED_DATA_REF_KEY: {
591 struct btrfs_shared_data_ref *sdref;
592 int count;
593
594 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
595 count = btrfs_shared_data_ref_count(leaf, sdref);
596 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
597 bytenr, count, GFP_NOFS);
598 break;
599 }
600 case BTRFS_TREE_BLOCK_REF_KEY:
601 ret = __add_prelim_ref(prefs, offset, NULL,
602 *info_level + 1, 0,
603 bytenr, 1, GFP_NOFS);
604 break;
605 case BTRFS_EXTENT_DATA_REF_KEY: {
606 struct btrfs_extent_data_ref *dref;
607 int count;
608 u64 root;
609
610 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
611 count = btrfs_extent_data_ref_count(leaf, dref);
612 key.objectid = btrfs_extent_data_ref_objectid(leaf,
613 dref);
614 key.type = BTRFS_EXTENT_DATA_KEY;
615 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
616 root = btrfs_extent_data_ref_root(leaf, dref);
617 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
618 bytenr, count, GFP_NOFS);
619 break;
620 }
621 default:
622 WARN_ON(1);
623 }
624 if (ret)
625 return ret;
626 ptr += btrfs_extent_inline_ref_size(type);
627 }
628
629 return 0;
630 }
631
632 /*
633 * add all non-inline backrefs for bytenr to the list
634 */
635 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
636 struct btrfs_path *path, u64 bytenr,
637 int info_level, struct list_head *prefs)
638 {
639 struct btrfs_root *extent_root = fs_info->extent_root;
640 int ret;
641 int slot;
642 struct extent_buffer *leaf;
643 struct btrfs_key key;
644
645 while (1) {
646 ret = btrfs_next_item(extent_root, path);
647 if (ret < 0)
648 break;
649 if (ret) {
650 ret = 0;
651 break;
652 }
653
654 slot = path->slots[0];
655 leaf = path->nodes[0];
656 btrfs_item_key_to_cpu(leaf, &key, slot);
657
658 if (key.objectid != bytenr)
659 break;
660 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
661 continue;
662 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
663 break;
664
665 switch (key.type) {
666 case BTRFS_SHARED_BLOCK_REF_KEY:
667 ret = __add_prelim_ref(prefs, 0, NULL,
668 info_level + 1, key.offset,
669 bytenr, 1, GFP_NOFS);
670 break;
671 case BTRFS_SHARED_DATA_REF_KEY: {
672 struct btrfs_shared_data_ref *sdref;
673 int count;
674
675 sdref = btrfs_item_ptr(leaf, slot,
676 struct btrfs_shared_data_ref);
677 count = btrfs_shared_data_ref_count(leaf, sdref);
678 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
679 bytenr, count, GFP_NOFS);
680 break;
681 }
682 case BTRFS_TREE_BLOCK_REF_KEY:
683 ret = __add_prelim_ref(prefs, key.offset, NULL,
684 info_level + 1, 0,
685 bytenr, 1, GFP_NOFS);
686 break;
687 case BTRFS_EXTENT_DATA_REF_KEY: {
688 struct btrfs_extent_data_ref *dref;
689 int count;
690 u64 root;
691
692 dref = btrfs_item_ptr(leaf, slot,
693 struct btrfs_extent_data_ref);
694 count = btrfs_extent_data_ref_count(leaf, dref);
695 key.objectid = btrfs_extent_data_ref_objectid(leaf,
696 dref);
697 key.type = BTRFS_EXTENT_DATA_KEY;
698 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
699 root = btrfs_extent_data_ref_root(leaf, dref);
700 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
701 bytenr, count, GFP_NOFS);
702 break;
703 }
704 default:
705 WARN_ON(1);
706 }
707 if (ret)
708 return ret;
709
710 }
711
712 return ret;
713 }
714
715 /*
716 * this adds all existing backrefs (inline backrefs, backrefs and delayed
717 * refs) for the given bytenr to the refs list, merges duplicates and resolves
718 * indirect refs to their parent bytenr.
719 * When roots are found, they're added to the roots list
720 *
721 * FIXME some caching might speed things up
722 */
723 static int find_parent_nodes(struct btrfs_trans_handle *trans,
724 struct btrfs_fs_info *fs_info, u64 bytenr,
725 u64 time_seq, struct ulist *refs,
726 struct ulist *roots, const u64 *extent_item_pos)
727 {
728 struct btrfs_key key;
729 struct btrfs_path *path;
730 int info_level = 0;
731 int ret;
732 struct list_head prefs;
733 struct __prelim_ref *ref;
734 struct extent_inode_elem *eie = NULL;
735 u64 total_refs = 0;
736
737 INIT_LIST_HEAD(&prefs);
738
739 key.objectid = bytenr;
740 key.offset = (u64)-1;
741 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
742 key.type = BTRFS_METADATA_ITEM_KEY;
743 else
744 key.type = BTRFS_EXTENT_ITEM_KEY;
745
746 path = btrfs_alloc_path();
747 if (!path)
748 return -ENOMEM;
749
750 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
751 if (ret < 0)
752 goto out;
753 BUG_ON(ret == 0);
754
755 if (path->slots[0]) {
756 struct extent_buffer *leaf;
757 int slot;
758
759 path->slots[0]--;
760 leaf = path->nodes[0];
761 slot = path->slots[0];
762 btrfs_item_key_to_cpu(leaf, &key, slot);
763 if (key.objectid == bytenr &&
764 (key.type == BTRFS_EXTENT_ITEM_KEY ||
765 key.type == BTRFS_METADATA_ITEM_KEY)) {
766 ret = __add_inline_refs(fs_info, path, bytenr,
767 &info_level, &prefs,
768 &total_refs);
769 if (ret)
770 goto out;
771 ret = __add_keyed_refs(fs_info, path, bytenr,
772 info_level, &prefs);
773 if (ret)
774 goto out;
775 }
776 }
777 btrfs_release_path(path);
778
779 ret = __add_missing_keys(fs_info, &prefs);
780 if (ret)
781 goto out;
782
783 __merge_refs(&prefs, 1);
784
785 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
786 extent_item_pos, total_refs);
787 if (ret)
788 goto out;
789
790 __merge_refs(&prefs, 2);
791
792 while (!list_empty(&prefs)) {
793 ref = list_first_entry(&prefs, struct __prelim_ref, list);
794 WARN_ON(ref->count < 0);
795 if (roots && ref->count && ref->root_id && ref->parent == 0) {
796 /* no parent == root of tree */
797 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
798 if (ret < 0)
799 goto out;
800 }
801 if (ref->count && ref->parent) {
802 if (extent_item_pos && !ref->inode_list &&
803 ref->level == 0) {
804 struct extent_buffer *eb;
805
806 eb = read_tree_block(fs_info, ref->parent, 0);
807 if (!extent_buffer_uptodate(eb)) {
808 free_extent_buffer(eb);
809 ret = -EIO;
810 goto out;
811 }
812 ret = find_extent_in_eb(eb, bytenr,
813 *extent_item_pos, &eie);
814 free_extent_buffer(eb);
815 if (ret < 0)
816 goto out;
817 ref->inode_list = eie;
818 }
819 ret = ulist_add_merge_ptr(refs, ref->parent,
820 ref->inode_list,
821 (void **)&eie, GFP_NOFS);
822 if (ret < 0)
823 goto out;
824 if (!ret && extent_item_pos) {
825 /*
826 * we've recorded that parent, so we must extend
827 * its inode list here
828 */
829 BUG_ON(!eie);
830 while (eie->next)
831 eie = eie->next;
832 eie->next = ref->inode_list;
833 }
834 eie = NULL;
835 }
836 list_del(&ref->list);
837 kfree(ref);
838 }
839
840 out:
841 btrfs_free_path(path);
842 while (!list_empty(&prefs)) {
843 ref = list_first_entry(&prefs, struct __prelim_ref, list);
844 list_del(&ref->list);
845 kfree(ref);
846 }
847 if (ret < 0)
848 free_inode_elem_list(eie);
849 return ret;
850 }
851
852 static void free_leaf_list(struct ulist *blocks)
853 {
854 struct ulist_node *node = NULL;
855 struct extent_inode_elem *eie;
856 struct ulist_iterator uiter;
857
858 ULIST_ITER_INIT(&uiter);
859 while ((node = ulist_next(blocks, &uiter))) {
860 if (!node->aux)
861 continue;
862 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
863 free_inode_elem_list(eie);
864 node->aux = 0;
865 }
866
867 ulist_free(blocks);
868 }
869
870 /*
871 * Finds all leafs with a reference to the specified combination of bytenr and
872 * offset. key_list_head will point to a list of corresponding keys (caller must
873 * free each list element). The leafs will be stored in the leafs ulist, which
874 * must be freed with ulist_free.
875 *
876 * returns 0 on success, <0 on error
877 */
878 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
879 struct btrfs_fs_info *fs_info, u64 bytenr,
880 u64 time_seq, struct ulist **leafs,
881 const u64 *extent_item_pos)
882 {
883 int ret;
884
885 *leafs = ulist_alloc(GFP_NOFS);
886 if (!*leafs)
887 return -ENOMEM;
888
889 ret = find_parent_nodes(trans, fs_info, bytenr,
890 time_seq, *leafs, NULL, extent_item_pos);
891 if (ret < 0 && ret != -ENOENT) {
892 free_leaf_list(*leafs);
893 return ret;
894 }
895
896 return 0;
897 }
898
899 /*
900 * walk all backrefs for a given extent to find all roots that reference this
901 * extent. Walking a backref means finding all extents that reference this
902 * extent and in turn walk the backrefs of those, too. Naturally this is a
903 * recursive process, but here it is implemented in an iterative fashion: We
904 * find all referencing extents for the extent in question and put them on a
905 * list. In turn, we find all referencing extents for those, further appending
906 * to the list. The way we iterate the list allows adding more elements after
907 * the current while iterating. The process stops when we reach the end of the
908 * list. Found roots are added to the roots list.
909 *
910 * returns 0 on success, < 0 on error.
911 */
912 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
913 struct btrfs_fs_info *fs_info, u64 bytenr,
914 u64 time_seq, struct ulist **roots)
915 {
916 struct ulist *tmp;
917 struct ulist_node *node = NULL;
918 struct ulist_iterator uiter;
919 int ret;
920
921 tmp = ulist_alloc(GFP_NOFS);
922 if (!tmp)
923 return -ENOMEM;
924 *roots = ulist_alloc(GFP_NOFS);
925 if (!*roots) {
926 ulist_free(tmp);
927 return -ENOMEM;
928 }
929
930 ULIST_ITER_INIT(&uiter);
931 while (1) {
932 ret = find_parent_nodes(trans, fs_info, bytenr,
933 time_seq, tmp, *roots, NULL);
934 if (ret < 0 && ret != -ENOENT) {
935 ulist_free(tmp);
936 ulist_free(*roots);
937 return ret;
938 }
939 node = ulist_next(tmp, &uiter);
940 if (!node)
941 break;
942 bytenr = node->val;
943 cond_resched();
944 }
945
946 ulist_free(tmp);
947 return 0;
948 }
949
950 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
951 struct btrfs_fs_info *fs_info, u64 bytenr,
952 u64 time_seq, struct ulist **roots)
953 {
954 return __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
955 }
956
957 /*
958 * this makes the path point to (inum INODE_ITEM ioff)
959 */
960 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
961 struct btrfs_path *path)
962 {
963 struct btrfs_key key;
964 return btrfs_find_item(fs_root, path, inum, ioff,
965 BTRFS_INODE_ITEM_KEY, &key);
966 }
967
968 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
969 struct btrfs_path *path,
970 struct btrfs_key *found_key)
971 {
972 return btrfs_find_item(fs_root, path, inum, ioff,
973 BTRFS_INODE_REF_KEY, found_key);
974 }
975
976 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
977 u64 start_off, struct btrfs_path *path,
978 struct btrfs_inode_extref **ret_extref,
979 u64 *found_off)
980 {
981 int ret, slot;
982 struct btrfs_key key;
983 struct btrfs_key found_key;
984 struct btrfs_inode_extref *extref;
985 struct extent_buffer *leaf;
986 unsigned long ptr;
987
988 key.objectid = inode_objectid;
989 key.type = BTRFS_INODE_EXTREF_KEY;
990 key.offset = start_off;
991
992 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
993 if (ret < 0)
994 return ret;
995
996 while (1) {
997 leaf = path->nodes[0];
998 slot = path->slots[0];
999 if (slot >= btrfs_header_nritems(leaf)) {
1000 /*
1001 * If the item at offset is not found,
1002 * btrfs_search_slot will point us to the slot
1003 * where it should be inserted. In our case
1004 * that will be the slot directly before the
1005 * next INODE_REF_KEY_V2 item. In the case
1006 * that we're pointing to the last slot in a
1007 * leaf, we must move one leaf over.
1008 */
1009 ret = btrfs_next_leaf(root, path);
1010 if (ret) {
1011 if (ret >= 1)
1012 ret = -ENOENT;
1013 break;
1014 }
1015 continue;
1016 }
1017
1018 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1019
1020 /*
1021 * Check that we're still looking at an extended ref key for
1022 * this particular objectid. If we have different
1023 * objectid or type then there are no more to be found
1024 * in the tree and we can exit.
1025 */
1026 ret = -ENOENT;
1027 if (found_key.objectid != inode_objectid)
1028 break;
1029 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1030 break;
1031
1032 ret = 0;
1033 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1034 extref = (struct btrfs_inode_extref *)ptr;
1035 *ret_extref = extref;
1036 if (found_off)
1037 *found_off = found_key.offset;
1038 break;
1039 }
1040
1041 return ret;
1042 }
1043
1044 /*
1045 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1046 * Elements of the path are separated by '/' and the path is guaranteed to be
1047 * 0-terminated. the path is only given within the current file system.
1048 * Therefore, it never starts with a '/'. the caller is responsible to provide
1049 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1050 * the start point of the resulting string is returned. this pointer is within
1051 * dest, normally.
1052 * in case the path buffer would overflow, the pointer is decremented further
1053 * as if output was written to the buffer, though no more output is actually
1054 * generated. that way, the caller can determine how much space would be
1055 * required for the path to fit into the buffer. in that case, the returned
1056 * value will be smaller than dest. callers must check this!
1057 */
1058 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1059 u32 name_len, unsigned long name_off,
1060 struct extent_buffer *eb_in, u64 parent,
1061 char *dest, u32 size)
1062 {
1063 int slot;
1064 u64 next_inum;
1065 int ret;
1066 s64 bytes_left = ((s64)size) - 1;
1067 struct extent_buffer *eb = eb_in;
1068 struct btrfs_key found_key;
1069 struct btrfs_inode_ref *iref;
1070
1071 if (bytes_left >= 0)
1072 dest[bytes_left] = '\0';
1073
1074 while (1) {
1075 bytes_left -= name_len;
1076 if (bytes_left >= 0)
1077 read_extent_buffer(eb, dest + bytes_left,
1078 name_off, name_len);
1079 if (eb != eb_in)
1080 free_extent_buffer(eb);
1081 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1082 if (ret > 0)
1083 ret = -ENOENT;
1084 if (ret)
1085 break;
1086
1087 next_inum = found_key.offset;
1088
1089 /* regular exit ahead */
1090 if (parent == next_inum)
1091 break;
1092
1093 slot = path->slots[0];
1094 eb = path->nodes[0];
1095 /* make sure we can use eb after releasing the path */
1096 if (eb != eb_in)
1097 eb->refs++;
1098 btrfs_release_path(path);
1099 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1100
1101 name_len = btrfs_inode_ref_name_len(eb, iref);
1102 name_off = (unsigned long)(iref + 1);
1103
1104 parent = next_inum;
1105 --bytes_left;
1106 if (bytes_left >= 0)
1107 dest[bytes_left] = '/';
1108 }
1109
1110 btrfs_release_path(path);
1111
1112 if (ret)
1113 return ERR_PTR(ret);
1114
1115 return dest + bytes_left;
1116 }
1117
1118 /*
1119 * this makes the path point to (logical EXTENT_ITEM *)
1120 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1121 * tree blocks and <0 on error.
1122 */
1123 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1124 struct btrfs_path *path, struct btrfs_key *found_key,
1125 u64 *flags_ret)
1126 {
1127 int ret;
1128 u64 flags;
1129 u64 size = 0;
1130 u32 item_size;
1131 struct extent_buffer *eb;
1132 struct btrfs_extent_item *ei;
1133 struct btrfs_key key;
1134
1135 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1136 key.type = BTRFS_METADATA_ITEM_KEY;
1137 else
1138 key.type = BTRFS_EXTENT_ITEM_KEY;
1139 key.objectid = logical;
1140 key.offset = (u64)-1;
1141
1142 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1143 if (ret < 0)
1144 return ret;
1145
1146 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1147 if (ret) {
1148 if (ret > 0)
1149 ret = -ENOENT;
1150 return ret;
1151 }
1152 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1153 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1154 size = fs_info->nodesize;
1155 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1156 size = found_key->offset;
1157
1158 if (found_key->objectid > logical ||
1159 found_key->objectid + size <= logical) {
1160 pr_debug("logical %llu is not within any extent\n", logical);
1161 return -ENOENT;
1162 }
1163
1164 eb = path->nodes[0];
1165 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1166 BUG_ON(item_size < sizeof(*ei));
1167
1168 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1169 flags = btrfs_extent_flags(eb, ei);
1170
1171 pr_debug("logical %llu is at position %llu within the extent (%llu "
1172 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1173 logical, logical - found_key->objectid, found_key->objectid,
1174 found_key->offset, flags, item_size);
1175
1176 if (flags_ret) {
1177 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1178 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1179 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1180 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1181 else
1182 BUG_ON(1);
1183 return 0;
1184 } else {
1185 WARN_ON(1);
1186 return -EIO;
1187 }
1188 }
1189
1190 /*
1191 * helper function to iterate extent inline refs. ptr must point to a 0 value
1192 * for the first call and may be modified. it is used to track state.
1193 * if more refs exist, 0 is returned and the next call to
1194 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1195 * next ref. after the last ref was processed, 1 is returned.
1196 * returns <0 on error
1197 */
1198 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1199 struct btrfs_key *key,
1200 struct btrfs_extent_item *ei, u32 item_size,
1201 struct btrfs_extent_inline_ref **out_eiref,
1202 int *out_type)
1203 {
1204 unsigned long end;
1205 u64 flags;
1206 struct btrfs_tree_block_info *info;
1207
1208 if (!*ptr) {
1209 /* first call */
1210 flags = btrfs_extent_flags(eb, ei);
1211 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1212 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1213 /* a skinny metadata extent */
1214 *out_eiref =
1215 (struct btrfs_extent_inline_ref *)(ei + 1);
1216 } else {
1217 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1218 info = (struct btrfs_tree_block_info *)(ei + 1);
1219 *out_eiref =
1220 (struct btrfs_extent_inline_ref *)(info + 1);
1221 }
1222 } else {
1223 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1224 }
1225 *ptr = (unsigned long)*out_eiref;
1226 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1227 return -ENOENT;
1228 }
1229
1230 end = (unsigned long)ei + item_size;
1231 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1232 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1233
1234 *ptr += btrfs_extent_inline_ref_size(*out_type);
1235 WARN_ON(*ptr > end);
1236 if (*ptr == end)
1237 return 1; /* last */
1238
1239 return 0;
1240 }
1241
1242 /*
1243 * reads the tree block backref for an extent. tree level and root are returned
1244 * through out_level and out_root. ptr must point to a 0 value for the first
1245 * call and may be modified (see __get_extent_inline_ref comment).
1246 * returns 0 if data was provided, 1 if there was no more data to provide or
1247 * <0 on error.
1248 */
1249 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1250 struct btrfs_key *key, struct btrfs_extent_item *ei,
1251 u32 item_size, u64 *out_root, u8 *out_level)
1252 {
1253 int ret;
1254 int type;
1255 struct btrfs_tree_block_info *info;
1256 struct btrfs_extent_inline_ref *eiref;
1257
1258 if (*ptr == (unsigned long)-1)
1259 return 1;
1260
1261 while (1) {
1262 ret = __get_extent_inline_ref(ptr, eb, key, ei, item_size,
1263 &eiref, &type);
1264 if (ret < 0)
1265 return ret;
1266
1267 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1268 type == BTRFS_SHARED_BLOCK_REF_KEY)
1269 break;
1270
1271 if (ret == 1)
1272 return 1;
1273 }
1274
1275 /* we can treat both ref types equally here */
1276 info = (struct btrfs_tree_block_info *)(ei + 1);
1277 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1278 *out_level = btrfs_tree_block_level(eb, info);
1279
1280 if (ret == 1)
1281 *ptr = (unsigned long)-1;
1282
1283 return 0;
1284 }
1285
1286 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1287 u64 root, u64 extent_item_objectid,
1288 iterate_extent_inodes_t *iterate, void *ctx)
1289 {
1290 struct extent_inode_elem *eie;
1291 int ret = 0;
1292
1293 for (eie = inode_list; eie; eie = eie->next) {
1294 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1295 "root %llu\n", extent_item_objectid,
1296 eie->inum, eie->offset, root);
1297 ret = iterate(eie->inum, eie->offset, root, ctx);
1298 if (ret) {
1299 pr_debug("stopping iteration for %llu due to ret=%d\n",
1300 extent_item_objectid, ret);
1301 break;
1302 }
1303 }
1304
1305 return ret;
1306 }
1307
1308 /*
1309 * calls iterate() for every inode that references the extent identified by
1310 * the given parameters.
1311 * when the iterator function returns a non-zero value, iteration stops.
1312 */
1313 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1314 u64 extent_item_objectid, u64 extent_item_pos,
1315 int search_commit_root,
1316 iterate_extent_inodes_t *iterate, void *ctx)
1317 {
1318 int ret;
1319 struct btrfs_trans_handle *trans = NULL;
1320 struct ulist *refs = NULL;
1321 struct ulist *roots = NULL;
1322 struct ulist_node *ref_node = NULL;
1323 struct ulist_node *root_node = NULL;
1324 struct ulist_iterator ref_uiter;
1325 struct ulist_iterator root_uiter;
1326
1327 pr_debug("resolving all inodes for extent %llu\n",
1328 extent_item_objectid);
1329
1330 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1331 0, &refs, &extent_item_pos);
1332 if (ret)
1333 goto out;
1334
1335 ULIST_ITER_INIT(&ref_uiter);
1336 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1337 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
1338 0, &roots);
1339 if (ret)
1340 break;
1341 ULIST_ITER_INIT(&root_uiter);
1342 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1343 pr_debug("root %llu references leaf %llu, data list "
1344 "%#llx\n", root_node->val, ref_node->val,
1345 ref_node->aux);
1346 ret = iterate_leaf_refs((struct extent_inode_elem *)
1347 (uintptr_t)ref_node->aux,
1348 root_node->val,
1349 extent_item_objectid,
1350 iterate, ctx);
1351 }
1352 ulist_free(roots);
1353 }
1354
1355 free_leaf_list(refs);
1356 out:
1357 return ret;
1358 }
1359
1360 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1361 struct btrfs_path *path,
1362 iterate_extent_inodes_t *iterate, void *ctx)
1363 {
1364 int ret;
1365 u64 extent_item_pos;
1366 u64 flags = 0;
1367 struct btrfs_key found_key;
1368 int search_commit_root = 0;
1369
1370 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1371 btrfs_release_path(path);
1372 if (ret < 0)
1373 return ret;
1374 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1375 return -EINVAL;
1376
1377 extent_item_pos = logical - found_key.objectid;
1378 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1379 extent_item_pos, search_commit_root,
1380 iterate, ctx);
1381
1382 return ret;
1383 }
1384
1385 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1386 struct extent_buffer *eb, void *ctx);
1387
1388 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1389 struct btrfs_path *path,
1390 iterate_irefs_t *iterate, void *ctx)
1391 {
1392 int ret = 0;
1393 int slot;
1394 u32 cur;
1395 u32 len;
1396 u32 name_len;
1397 u64 parent = 0;
1398 int found = 0;
1399 struct extent_buffer *eb;
1400 struct btrfs_item *item;
1401 struct btrfs_inode_ref *iref;
1402 struct btrfs_key found_key;
1403
1404 while (!ret) {
1405 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1406 &found_key);
1407 if (ret < 0)
1408 break;
1409 if (ret) {
1410 ret = found ? 0 : -ENOENT;
1411 break;
1412 }
1413 ++found;
1414
1415 parent = found_key.offset;
1416 slot = path->slots[0];
1417 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1418 if (!eb) {
1419 ret = -ENOMEM;
1420 break;
1421 }
1422 extent_buffer_get(eb);
1423 btrfs_release_path(path);
1424
1425 item = btrfs_item_nr(slot);
1426 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1427
1428 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1429 name_len = btrfs_inode_ref_name_len(eb, iref);
1430 /* path must be released before calling iterate()! */
1431 pr_debug("following ref at offset %u for inode %llu in "
1432 "tree %llu\n", cur, found_key.objectid,
1433 fs_root->objectid);
1434 ret = iterate(parent, name_len,
1435 (unsigned long)(iref + 1), eb, ctx);
1436 if (ret)
1437 break;
1438 len = sizeof(*iref) + name_len;
1439 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1440 }
1441 free_extent_buffer(eb);
1442 }
1443
1444 btrfs_release_path(path);
1445
1446 return ret;
1447 }
1448
1449 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1450 struct btrfs_path *path,
1451 iterate_irefs_t *iterate, void *ctx)
1452 {
1453 int ret;
1454 int slot;
1455 u64 offset = 0;
1456 u64 parent;
1457 int found = 0;
1458 struct extent_buffer *eb;
1459 struct btrfs_inode_extref *extref;
1460 struct extent_buffer *leaf;
1461 u32 item_size;
1462 u32 cur_offset;
1463 unsigned long ptr;
1464
1465 while (1) {
1466 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1467 &offset);
1468 if (ret < 0)
1469 break;
1470 if (ret) {
1471 ret = found ? 0 : -ENOENT;
1472 break;
1473 }
1474 ++found;
1475
1476 slot = path->slots[0];
1477 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1478 if (!eb) {
1479 ret = -ENOMEM;
1480 break;
1481 }
1482 extent_buffer_get(eb);
1483
1484 btrfs_release_path(path);
1485
1486 leaf = path->nodes[0];
1487 item_size = btrfs_item_size_nr(leaf, slot);
1488 ptr = btrfs_item_ptr_offset(leaf, slot);
1489 cur_offset = 0;
1490
1491 while (cur_offset < item_size) {
1492 u32 name_len;
1493
1494 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1495 parent = btrfs_inode_extref_parent(eb, extref);
1496 name_len = btrfs_inode_extref_name_len(eb, extref);
1497 ret = iterate(parent, name_len,
1498 (unsigned long)&extref->name, eb, ctx);
1499 if (ret)
1500 break;
1501
1502 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1503 cur_offset += sizeof(*extref);
1504 }
1505 free_extent_buffer(eb);
1506
1507 offset++;
1508 }
1509
1510 btrfs_release_path(path);
1511
1512 return ret;
1513 }
1514
1515 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1516 struct btrfs_path *path, iterate_irefs_t *iterate,
1517 void *ctx)
1518 {
1519 int ret;
1520 int found_refs = 0;
1521
1522 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1523 if (!ret)
1524 ++found_refs;
1525 else if (ret != -ENOENT)
1526 return ret;
1527
1528 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1529 if (ret == -ENOENT && found_refs)
1530 return 0;
1531
1532 return ret;
1533 }
1534
1535 /*
1536 * returns 0 if the path could be dumped (probably truncated)
1537 * returns <0 in case of an error
1538 */
1539 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1540 struct extent_buffer *eb, void *ctx)
1541 {
1542 struct inode_fs_paths *ipath = ctx;
1543 char *fspath;
1544 char *fspath_min;
1545 int i = ipath->fspath->elem_cnt;
1546 const int s_ptr = sizeof(char *);
1547 u32 bytes_left;
1548
1549 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1550 ipath->fspath->bytes_left - s_ptr : 0;
1551
1552 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1553 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1554 name_off, eb, inum, fspath_min, bytes_left);
1555 if (IS_ERR(fspath))
1556 return PTR_ERR(fspath);
1557
1558 if (fspath > fspath_min) {
1559 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1560 ++ipath->fspath->elem_cnt;
1561 ipath->fspath->bytes_left = fspath - fspath_min;
1562 } else {
1563 ++ipath->fspath->elem_missed;
1564 ipath->fspath->bytes_missing += fspath_min - fspath;
1565 ipath->fspath->bytes_left = 0;
1566 }
1567
1568 return 0;
1569 }
1570
1571 /*
1572 * this dumps all file system paths to the inode into the ipath struct, provided
1573 * is has been created large enough. each path is zero-terminated and accessed
1574 * from ipath->fspath->val[i].
1575 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1576 * in ipath->fspath->val[]. When the allocated space wasn't sufficient, the
1577 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
1578 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1579 * have been needed to return all paths.
1580 */
1581 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1582 {
1583 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1584 inode_to_path, ipath);
1585 }
1586
1587 struct btrfs_data_container *init_data_container(u32 total_bytes)
1588 {
1589 struct btrfs_data_container *data;
1590 size_t alloc_bytes;
1591
1592 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1593 data = vmalloc(alloc_bytes);
1594 if (!data)
1595 return ERR_PTR(-ENOMEM);
1596
1597 if (total_bytes >= sizeof(*data)) {
1598 data->bytes_left = total_bytes - sizeof(*data);
1599 data->bytes_missing = 0;
1600 } else {
1601 data->bytes_missing = sizeof(*data) - total_bytes;
1602 data->bytes_left = 0;
1603 }
1604
1605 data->elem_cnt = 0;
1606 data->elem_missed = 0;
1607
1608 return data;
1609 }
1610
1611 /*
1612 * allocates space to return multiple file system paths for an inode.
1613 * total_bytes to allocate are passed, note that space usable for actual path
1614 * information will be total_bytes - sizeof(struct inode_fs_paths).
1615 * the returned pointer must be freed with free_ipath() in the end.
1616 */
1617 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1618 struct btrfs_path *path)
1619 {
1620 struct inode_fs_paths *ifp;
1621 struct btrfs_data_container *fspath;
1622
1623 fspath = init_data_container(total_bytes);
1624 if (IS_ERR(fspath))
1625 return (void *)fspath;
1626
1627 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1628 if (!ifp) {
1629 kfree(fspath);
1630 return ERR_PTR(-ENOMEM);
1631 }
1632
1633 ifp->btrfs_path = path;
1634 ifp->fspath = fspath;
1635 ifp->fs_root = fs_root;
1636
1637 return ifp;
1638 }
1639
1640 void free_ipath(struct inode_fs_paths *ipath)
1641 {
1642 if (!ipath)
1643 return;
1644 vfree(ipath->fspath);
1645 kfree(ipath);
1646 }
(deprecated) Btrfs progs developments and patch integration