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Btrfs progs v4.10.2
[btrfs-progs-unstable/devel.git] / backref.c
blobe1f41e1a0dd0ec57963aae400d4fbab1e1b88b3d
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->tree_root, ref->wanted_disk_byte,
454 fs_info->tree_root->nodesize, 0);
455 if (!extent_buffer_uptodate(eb)) {
456 free_extent_buffer(eb);
457 return -EIO;
458 }
459 if (btrfs_header_level(eb) == 0)
460 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
461 else
462 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
463 free_extent_buffer(eb);
464 }
465 return 0;
466 }
467
468 /*
469 * merge two lists of backrefs and adjust counts accordingly
470 *
471 * mode = 1: merge identical keys, if key is set
472 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
473 * additionally, we could even add a key range for the blocks we
474 * looked into to merge even more (-> replace unresolved refs by those
475 * having a parent).
476 * mode = 2: merge identical parents
477 */
478 static void __merge_refs(struct list_head *head, int mode)
479 {
480 struct list_head *pos1;
481
482 list_for_each(pos1, head) {
483 struct list_head *n2;
484 struct list_head *pos2;
485 struct __prelim_ref *ref1;
486
487 ref1 = list_entry(pos1, struct __prelim_ref, list);
488
489 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
490 pos2 = n2, n2 = pos2->next) {
491 struct __prelim_ref *ref2;
492 struct __prelim_ref *xchg;
493 struct extent_inode_elem *eie;
494
495 ref2 = list_entry(pos2, struct __prelim_ref, list);
496
497 if (mode == 1) {
498 if (!ref_for_same_block(ref1, ref2))
499 continue;
500 if (!ref1->parent && ref2->parent) {
501 xchg = ref1;
502 ref1 = ref2;
503 ref2 = xchg;
504 }
505 } else {
506 if (ref1->parent != ref2->parent)
507 continue;
508 }
509
510 eie = ref1->inode_list;
511 while (eie && eie->next)
512 eie = eie->next;
513 if (eie)
514 eie->next = ref2->inode_list;
515 else
516 ref1->inode_list = ref2->inode_list;
517 ref1->count += ref2->count;
518
519 list_del(&ref2->list);
520 kfree(ref2);
521 }
522
523 }
524 }
525
526 /*
527 * add all inline backrefs for bytenr to the list
528 */
529 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
530 struct btrfs_path *path, u64 bytenr,
531 int *info_level, struct list_head *prefs,
532 u64 *total_refs)
533 {
534 int ret = 0;
535 int slot;
536 struct extent_buffer *leaf;
537 struct btrfs_key key;
538 struct btrfs_key found_key;
539 unsigned long ptr;
540 unsigned long end;
541 struct btrfs_extent_item *ei;
542 u64 flags;
543 u64 item_size;
544
545 /*
546 * enumerate all inline refs
547 */
548 leaf = path->nodes[0];
549 slot = path->slots[0];
550
551 item_size = btrfs_item_size_nr(leaf, slot);
552 BUG_ON(item_size < sizeof(*ei));
553
554 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
555 flags = btrfs_extent_flags(leaf, ei);
556 *total_refs += btrfs_extent_refs(leaf, ei);
557 btrfs_item_key_to_cpu(leaf, &found_key, slot);
558
559 ptr = (unsigned long)(ei + 1);
560 end = (unsigned long)ei + item_size;
561
562 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
563 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
564 struct btrfs_tree_block_info *info;
565
566 info = (struct btrfs_tree_block_info *)ptr;
567 *info_level = btrfs_tree_block_level(leaf, info);
568 ptr += sizeof(struct btrfs_tree_block_info);
569 BUG_ON(ptr > end);
570 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
571 *info_level = found_key.offset;
572 } else {
573 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
574 }
575
576 while (ptr < end) {
577 struct btrfs_extent_inline_ref *iref;
578 u64 offset;
579 int type;
580
581 iref = (struct btrfs_extent_inline_ref *)ptr;
582 type = btrfs_extent_inline_ref_type(leaf, iref);
583 offset = btrfs_extent_inline_ref_offset(leaf, iref);
584
585 switch (type) {
586 case BTRFS_SHARED_BLOCK_REF_KEY:
587 ret = __add_prelim_ref(prefs, 0, NULL,
588 *info_level + 1, offset,
589 bytenr, 1, GFP_NOFS);
590 break;
591 case BTRFS_SHARED_DATA_REF_KEY: {
592 struct btrfs_shared_data_ref *sdref;
593 int count;
594
595 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
596 count = btrfs_shared_data_ref_count(leaf, sdref);
597 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
598 bytenr, count, GFP_NOFS);
599 break;
600 }
601 case BTRFS_TREE_BLOCK_REF_KEY:
602 ret = __add_prelim_ref(prefs, offset, NULL,
603 *info_level + 1, 0,
604 bytenr, 1, GFP_NOFS);
605 break;
606 case BTRFS_EXTENT_DATA_REF_KEY: {
607 struct btrfs_extent_data_ref *dref;
608 int count;
609 u64 root;
610
611 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
612 count = btrfs_extent_data_ref_count(leaf, dref);
613 key.objectid = btrfs_extent_data_ref_objectid(leaf,
614 dref);
615 key.type = BTRFS_EXTENT_DATA_KEY;
616 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
617 root = btrfs_extent_data_ref_root(leaf, dref);
618 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
619 bytenr, count, GFP_NOFS);
620 break;
621 }
622 default:
623 WARN_ON(1);
624 }
625 if (ret)
626 return ret;
627 ptr += btrfs_extent_inline_ref_size(type);
628 }
629
630 return 0;
631 }
632
633 /*
634 * add all non-inline backrefs for bytenr to the list
635 */
636 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
637 struct btrfs_path *path, u64 bytenr,
638 int info_level, struct list_head *prefs)
639 {
640 struct btrfs_root *extent_root = fs_info->extent_root;
641 int ret;
642 int slot;
643 struct extent_buffer *leaf;
644 struct btrfs_key key;
645
646 while (1) {
647 ret = btrfs_next_item(extent_root, path);
648 if (ret < 0)
649 break;
650 if (ret) {
651 ret = 0;
652 break;
653 }
654
655 slot = path->slots[0];
656 leaf = path->nodes[0];
657 btrfs_item_key_to_cpu(leaf, &key, slot);
658
659 if (key.objectid != bytenr)
660 break;
661 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
662 continue;
663 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
664 break;
665
666 switch (key.type) {
667 case BTRFS_SHARED_BLOCK_REF_KEY:
668 ret = __add_prelim_ref(prefs, 0, NULL,
669 info_level + 1, key.offset,
670 bytenr, 1, GFP_NOFS);
671 break;
672 case BTRFS_SHARED_DATA_REF_KEY: {
673 struct btrfs_shared_data_ref *sdref;
674 int count;
675
676 sdref = btrfs_item_ptr(leaf, slot,
677 struct btrfs_shared_data_ref);
678 count = btrfs_shared_data_ref_count(leaf, sdref);
679 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
680 bytenr, count, GFP_NOFS);
681 break;
682 }
683 case BTRFS_TREE_BLOCK_REF_KEY:
684 ret = __add_prelim_ref(prefs, key.offset, NULL,
685 info_level + 1, 0,
686 bytenr, 1, GFP_NOFS);
687 break;
688 case BTRFS_EXTENT_DATA_REF_KEY: {
689 struct btrfs_extent_data_ref *dref;
690 int count;
691 u64 root;
692
693 dref = btrfs_item_ptr(leaf, slot,
694 struct btrfs_extent_data_ref);
695 count = btrfs_extent_data_ref_count(leaf, dref);
696 key.objectid = btrfs_extent_data_ref_objectid(leaf,
697 dref);
698 key.type = BTRFS_EXTENT_DATA_KEY;
699 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
700 root = btrfs_extent_data_ref_root(leaf, dref);
701 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
702 bytenr, count, GFP_NOFS);
703 break;
704 }
705 default:
706 WARN_ON(1);
707 }
708 if (ret)
709 return ret;
710
711 }
712
713 return ret;
714 }
715
716 /*
717 * this adds all existing backrefs (inline backrefs, backrefs and delayed
718 * refs) for the given bytenr to the refs list, merges duplicates and resolves
719 * indirect refs to their parent bytenr.
720 * When roots are found, they're added to the roots list
721 *
722 * FIXME some caching might speed things up
723 */
724 static int find_parent_nodes(struct btrfs_trans_handle *trans,
725 struct btrfs_fs_info *fs_info, u64 bytenr,
726 u64 time_seq, struct ulist *refs,
727 struct ulist *roots, const u64 *extent_item_pos)
728 {
729 struct btrfs_key key;
730 struct btrfs_path *path;
731 int info_level = 0;
732 int ret;
733 struct list_head prefs;
734 struct __prelim_ref *ref;
735 struct extent_inode_elem *eie = NULL;
736 u64 total_refs = 0;
737
738 INIT_LIST_HEAD(&prefs);
739
740 key.objectid = bytenr;
741 key.offset = (u64)-1;
742 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
743 key.type = BTRFS_METADATA_ITEM_KEY;
744 else
745 key.type = BTRFS_EXTENT_ITEM_KEY;
746
747 path = btrfs_alloc_path();
748 if (!path)
749 return -ENOMEM;
750
751 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
752 if (ret < 0)
753 goto out;
754 BUG_ON(ret == 0);
755
756 if (path->slots[0]) {
757 struct extent_buffer *leaf;
758 int slot;
759
760 path->slots[0]--;
761 leaf = path->nodes[0];
762 slot = path->slots[0];
763 btrfs_item_key_to_cpu(leaf, &key, slot);
764 if (key.objectid == bytenr &&
765 (key.type == BTRFS_EXTENT_ITEM_KEY ||
766 key.type == BTRFS_METADATA_ITEM_KEY)) {
767 ret = __add_inline_refs(fs_info, path, bytenr,
768 &info_level, &prefs,
769 &total_refs);
770 if (ret)
771 goto out;
772 ret = __add_keyed_refs(fs_info, path, bytenr,
773 info_level, &prefs);
774 if (ret)
775 goto out;
776 }
777 }
778 btrfs_release_path(path);
779
780 ret = __add_missing_keys(fs_info, &prefs);
781 if (ret)
782 goto out;
783
784 __merge_refs(&prefs, 1);
785
786 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
787 extent_item_pos, total_refs);
788 if (ret)
789 goto out;
790
791 __merge_refs(&prefs, 2);
792
793 while (!list_empty(&prefs)) {
794 ref = list_first_entry(&prefs, struct __prelim_ref, list);
795 WARN_ON(ref->count < 0);
796 if (roots && ref->count && ref->root_id && ref->parent == 0) {
797 /* no parent == root of tree */
798 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
799 if (ret < 0)
800 goto out;
801 }
802 if (ref->count && ref->parent) {
803 if (extent_item_pos && !ref->inode_list &&
804 ref->level == 0) {
805 u32 bsz;
806 struct extent_buffer *eb;
807 bsz = fs_info->extent_root->nodesize;
808 eb = read_tree_block(fs_info->extent_root,
809 ref->parent, bsz, 0);
810 if (!extent_buffer_uptodate(eb)) {
811 free_extent_buffer(eb);
812 ret = -EIO;
813 goto out;
814 }
815 ret = find_extent_in_eb(eb, bytenr,
816 *extent_item_pos, &eie);
817 free_extent_buffer(eb);
818 if (ret < 0)
819 goto out;
820 ref->inode_list = eie;
821 }
822 ret = ulist_add_merge_ptr(refs, ref->parent,
823 ref->inode_list,
824 (void **)&eie, GFP_NOFS);
825 if (ret < 0)
826 goto out;
827 if (!ret && extent_item_pos) {
828 /*
829 * we've recorded that parent, so we must extend
830 * its inode list here
831 */
832 BUG_ON(!eie);
833 while (eie->next)
834 eie = eie->next;
835 eie->next = ref->inode_list;
836 }
837 eie = NULL;
838 }
839 list_del(&ref->list);
840 kfree(ref);
841 }
842
843 out:
844 btrfs_free_path(path);
845 while (!list_empty(&prefs)) {
846 ref = list_first_entry(&prefs, struct __prelim_ref, list);
847 list_del(&ref->list);
848 kfree(ref);
849 }
850 if (ret < 0)
851 free_inode_elem_list(eie);
852 return ret;
853 }
854
855 static void free_leaf_list(struct ulist *blocks)
856 {
857 struct ulist_node *node = NULL;
858 struct extent_inode_elem *eie;
859 struct ulist_iterator uiter;
860
861 ULIST_ITER_INIT(&uiter);
862 while ((node = ulist_next(blocks, &uiter))) {
863 if (!node->aux)
864 continue;
865 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
866 free_inode_elem_list(eie);
867 node->aux = 0;
868 }
869
870 ulist_free(blocks);
871 }
872
873 /*
874 * Finds all leafs with a reference to the specified combination of bytenr and
875 * offset. key_list_head will point to a list of corresponding keys (caller must
876 * free each list element). The leafs will be stored in the leafs ulist, which
877 * must be freed with ulist_free.
878 *
879 * returns 0 on success, <0 on error
880 */
881 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
882 struct btrfs_fs_info *fs_info, u64 bytenr,
883 u64 time_seq, struct ulist **leafs,
884 const u64 *extent_item_pos)
885 {
886 int ret;
887
888 *leafs = ulist_alloc(GFP_NOFS);
889 if (!*leafs)
890 return -ENOMEM;
891
892 ret = find_parent_nodes(trans, fs_info, bytenr,
893 time_seq, *leafs, NULL, extent_item_pos);
894 if (ret < 0 && ret != -ENOENT) {
895 free_leaf_list(*leafs);
896 return ret;
897 }
898
899 return 0;
900 }
901
902 /*
903 * walk all backrefs for a given extent to find all roots that reference this
904 * extent. Walking a backref means finding all extents that reference this
905 * extent and in turn walk the backrefs of those, too. Naturally this is a
906 * recursive process, but here it is implemented in an iterative fashion: We
907 * find all referencing extents for the extent in question and put them on a
908 * list. In turn, we find all referencing extents for those, further appending
909 * to the list. The way we iterate the list allows adding more elements after
910 * the current while iterating. The process stops when we reach the end of the
911 * list. Found roots are added to the roots list.
912 *
913 * returns 0 on success, < 0 on error.
914 */
915 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
916 struct btrfs_fs_info *fs_info, u64 bytenr,
917 u64 time_seq, struct ulist **roots)
918 {
919 struct ulist *tmp;
920 struct ulist_node *node = NULL;
921 struct ulist_iterator uiter;
922 int ret;
923
924 tmp = ulist_alloc(GFP_NOFS);
925 if (!tmp)
926 return -ENOMEM;
927 *roots = ulist_alloc(GFP_NOFS);
928 if (!*roots) {
929 ulist_free(tmp);
930 return -ENOMEM;
931 }
932
933 ULIST_ITER_INIT(&uiter);
934 while (1) {
935 ret = find_parent_nodes(trans, fs_info, bytenr,
936 time_seq, tmp, *roots, NULL);
937 if (ret < 0 && ret != -ENOENT) {
938 ulist_free(tmp);
939 ulist_free(*roots);
940 return ret;
941 }
942 node = ulist_next(tmp, &uiter);
943 if (!node)
944 break;
945 bytenr = node->val;
946 cond_resched();
947 }
948
949 ulist_free(tmp);
950 return 0;
951 }
952
953 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
954 struct btrfs_fs_info *fs_info, u64 bytenr,
955 u64 time_seq, struct ulist **roots)
956 {
957 return __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
958 }
959
960 /*
961 * this makes the path point to (inum INODE_ITEM ioff)
962 */
963 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
964 struct btrfs_path *path)
965 {
966 struct btrfs_key key;
967 return btrfs_find_item(fs_root, path, inum, ioff,
968 BTRFS_INODE_ITEM_KEY, &key);
969 }
970
971 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
972 struct btrfs_path *path,
973 struct btrfs_key *found_key)
974 {
975 return btrfs_find_item(fs_root, path, inum, ioff,
976 BTRFS_INODE_REF_KEY, found_key);
977 }
978
979 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
980 u64 start_off, struct btrfs_path *path,
981 struct btrfs_inode_extref **ret_extref,
982 u64 *found_off)
983 {
984 int ret, slot;
985 struct btrfs_key key;
986 struct btrfs_key found_key;
987 struct btrfs_inode_extref *extref;
988 struct extent_buffer *leaf;
989 unsigned long ptr;
990
991 key.objectid = inode_objectid;
992 key.type = BTRFS_INODE_EXTREF_KEY;
993 key.offset = start_off;
994
995 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
996 if (ret < 0)
997 return ret;
998
999 while (1) {
1000 leaf = path->nodes[0];
1001 slot = path->slots[0];
1002 if (slot >= btrfs_header_nritems(leaf)) {
1003 /*
1004 * If the item at offset is not found,
1005 * btrfs_search_slot will point us to the slot
1006 * where it should be inserted. In our case
1007 * that will be the slot directly before the
1008 * next INODE_REF_KEY_V2 item. In the case
1009 * that we're pointing to the last slot in a
1010 * leaf, we must move one leaf over.
1011 */
1012 ret = btrfs_next_leaf(root, path);
1013 if (ret) {
1014 if (ret >= 1)
1015 ret = -ENOENT;
1016 break;
1017 }
1018 continue;
1019 }
1020
1021 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1022
1023 /*
1024 * Check that we're still looking at an extended ref key for
1025 * this particular objectid. If we have different
1026 * objectid or type then there are no more to be found
1027 * in the tree and we can exit.
1028 */
1029 ret = -ENOENT;
1030 if (found_key.objectid != inode_objectid)
1031 break;
1032 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1033 break;
1034
1035 ret = 0;
1036 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1037 extref = (struct btrfs_inode_extref *)ptr;
1038 *ret_extref = extref;
1039 if (found_off)
1040 *found_off = found_key.offset;
1041 break;
1042 }
1043
1044 return ret;
1045 }
1046
1047 /*
1048 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1049 * Elements of the path are separated by '/' and the path is guaranteed to be
1050 * 0-terminated. the path is only given within the current file system.
1051 * Therefore, it never starts with a '/'. the caller is responsible to provide
1052 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1053 * the start point of the resulting string is returned. this pointer is within
1054 * dest, normally.
1055 * in case the path buffer would overflow, the pointer is decremented further
1056 * as if output was written to the buffer, though no more output is actually
1057 * generated. that way, the caller can determine how much space would be
1058 * required for the path to fit into the buffer. in that case, the returned
1059 * value will be smaller than dest. callers must check this!
1060 */
1061 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1062 u32 name_len, unsigned long name_off,
1063 struct extent_buffer *eb_in, u64 parent,
1064 char *dest, u32 size)
1065 {
1066 int slot;
1067 u64 next_inum;
1068 int ret;
1069 s64 bytes_left = ((s64)size) - 1;
1070 struct extent_buffer *eb = eb_in;
1071 struct btrfs_key found_key;
1072 struct btrfs_inode_ref *iref;
1073
1074 if (bytes_left >= 0)
1075 dest[bytes_left] = '\0';
1076
1077 while (1) {
1078 bytes_left -= name_len;
1079 if (bytes_left >= 0)
1080 read_extent_buffer(eb, dest + bytes_left,
1081 name_off, name_len);
1082 if (eb != eb_in)
1083 free_extent_buffer(eb);
1084 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1085 if (ret > 0)
1086 ret = -ENOENT;
1087 if (ret)
1088 break;
1089
1090 next_inum = found_key.offset;
1091
1092 /* regular exit ahead */
1093 if (parent == next_inum)
1094 break;
1095
1096 slot = path->slots[0];
1097 eb = path->nodes[0];
1098 /* make sure we can use eb after releasing the path */
1099 if (eb != eb_in)
1100 eb->refs++;
1101 btrfs_release_path(path);
1102 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1103
1104 name_len = btrfs_inode_ref_name_len(eb, iref);
1105 name_off = (unsigned long)(iref + 1);
1106
1107 parent = next_inum;
1108 --bytes_left;
1109 if (bytes_left >= 0)
1110 dest[bytes_left] = '/';
1111 }
1112
1113 btrfs_release_path(path);
1114
1115 if (ret)
1116 return ERR_PTR(ret);
1117
1118 return dest + bytes_left;
1119 }
1120
1121 /*
1122 * this makes the path point to (logical EXTENT_ITEM *)
1123 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1124 * tree blocks and <0 on error.
1125 */
1126 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1127 struct btrfs_path *path, struct btrfs_key *found_key,
1128 u64 *flags_ret)
1129 {
1130 int ret;
1131 u64 flags;
1132 u64 size = 0;
1133 u32 item_size;
1134 struct extent_buffer *eb;
1135 struct btrfs_extent_item *ei;
1136 struct btrfs_key key;
1137
1138 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1139 key.type = BTRFS_METADATA_ITEM_KEY;
1140 else
1141 key.type = BTRFS_EXTENT_ITEM_KEY;
1142 key.objectid = logical;
1143 key.offset = (u64)-1;
1144
1145 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1146 if (ret < 0)
1147 return ret;
1148
1149 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1150 if (ret) {
1151 if (ret > 0)
1152 ret = -ENOENT;
1153 return ret;
1154 }
1155 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1156 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1157 size = fs_info->extent_root->nodesize;
1158 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1159 size = found_key->offset;
1160
1161 if (found_key->objectid > logical ||
1162 found_key->objectid + size <= logical) {
1163 pr_debug("logical %llu is not within any extent\n", logical);
1164 return -ENOENT;
1165 }
1166
1167 eb = path->nodes[0];
1168 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1169 BUG_ON(item_size < sizeof(*ei));
1170
1171 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1172 flags = btrfs_extent_flags(eb, ei);
1173
1174 pr_debug("logical %llu is at position %llu within the extent (%llu "
1175 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1176 logical, logical - found_key->objectid, found_key->objectid,
1177 found_key->offset, flags, item_size);
1178
1179 if (flags_ret) {
1180 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1181 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1182 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1183 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1184 else
1185 BUG_ON(1);
1186 return 0;
1187 } else {
1188 WARN_ON(1);
1189 return -EIO;
1190 }
1191 }
1192
1193 /*
1194 * helper function to iterate extent inline refs. ptr must point to a 0 value
1195 * for the first call and may be modified. it is used to track state.
1196 * if more refs exist, 0 is returned and the next call to
1197 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1198 * next ref. after the last ref was processed, 1 is returned.
1199 * returns <0 on error
1200 */
1201 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1202 struct btrfs_key *key,
1203 struct btrfs_extent_item *ei, u32 item_size,
1204 struct btrfs_extent_inline_ref **out_eiref,
1205 int *out_type)
1206 {
1207 unsigned long end;
1208 u64 flags;
1209 struct btrfs_tree_block_info *info;
1210
1211 if (!*ptr) {
1212 /* first call */
1213 flags = btrfs_extent_flags(eb, ei);
1214 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1215 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1216 /* a skinny metadata extent */
1217 *out_eiref =
1218 (struct btrfs_extent_inline_ref *)(ei + 1);
1219 } else {
1220 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1221 info = (struct btrfs_tree_block_info *)(ei + 1);
1222 *out_eiref =
1223 (struct btrfs_extent_inline_ref *)(info + 1);
1224 }
1225 } else {
1226 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1227 }
1228 *ptr = (unsigned long)*out_eiref;
1229 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1230 return -ENOENT;
1231 }
1232
1233 end = (unsigned long)ei + item_size;
1234 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1235 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1236
1237 *ptr += btrfs_extent_inline_ref_size(*out_type);
1238 WARN_ON(*ptr > end);
1239 if (*ptr == end)
1240 return 1; /* last */
1241
1242 return 0;
1243 }
1244
1245 /*
1246 * reads the tree block backref for an extent. tree level and root are returned
1247 * through out_level and out_root. ptr must point to a 0 value for the first
1248 * call and may be modified (see __get_extent_inline_ref comment).
1249 * returns 0 if data was provided, 1 if there was no more data to provide or
1250 * <0 on error.
1251 */
1252 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1253 struct btrfs_key *key, struct btrfs_extent_item *ei,
1254 u32 item_size, u64 *out_root, u8 *out_level)
1255 {
1256 int ret;
1257 int type;
1258 struct btrfs_tree_block_info *info;
1259 struct btrfs_extent_inline_ref *eiref;
1260
1261 if (*ptr == (unsigned long)-1)
1262 return 1;
1263
1264 while (1) {
1265 ret = __get_extent_inline_ref(ptr, eb, key, ei, item_size,
1266 &eiref, &type);
1267 if (ret < 0)
1268 return ret;
1269
1270 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1271 type == BTRFS_SHARED_BLOCK_REF_KEY)
1272 break;
1273
1274 if (ret == 1)
1275 return 1;
1276 }
1277
1278 /* we can treat both ref types equally here */
1279 info = (struct btrfs_tree_block_info *)(ei + 1);
1280 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1281 *out_level = btrfs_tree_block_level(eb, info);
1282
1283 if (ret == 1)
1284 *ptr = (unsigned long)-1;
1285
1286 return 0;
1287 }
1288
1289 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1290 u64 root, u64 extent_item_objectid,
1291 iterate_extent_inodes_t *iterate, void *ctx)
1292 {
1293 struct extent_inode_elem *eie;
1294 int ret = 0;
1295
1296 for (eie = inode_list; eie; eie = eie->next) {
1297 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1298 "root %llu\n", extent_item_objectid,
1299 eie->inum, eie->offset, root);
1300 ret = iterate(eie->inum, eie->offset, root, ctx);
1301 if (ret) {
1302 pr_debug("stopping iteration for %llu due to ret=%d\n",
1303 extent_item_objectid, ret);
1304 break;
1305 }
1306 }
1307
1308 return ret;
1309 }
1310
1311 /*
1312 * calls iterate() for every inode that references the extent identified by
1313 * the given parameters.
1314 * when the iterator function returns a non-zero value, iteration stops.
1315 */
1316 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1317 u64 extent_item_objectid, u64 extent_item_pos,
1318 int search_commit_root,
1319 iterate_extent_inodes_t *iterate, void *ctx)
1320 {
1321 int ret;
1322 struct btrfs_trans_handle *trans = NULL;
1323 struct ulist *refs = NULL;
1324 struct ulist *roots = NULL;
1325 struct ulist_node *ref_node = NULL;
1326 struct ulist_node *root_node = NULL;
1327 struct ulist_iterator ref_uiter;
1328 struct ulist_iterator root_uiter;
1329
1330 pr_debug("resolving all inodes for extent %llu\n",
1331 extent_item_objectid);
1332
1333 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1334 0, &refs, &extent_item_pos);
1335 if (ret)
1336 goto out;
1337
1338 ULIST_ITER_INIT(&ref_uiter);
1339 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1340 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
1341 0, &roots);
1342 if (ret)
1343 break;
1344 ULIST_ITER_INIT(&root_uiter);
1345 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1346 pr_debug("root %llu references leaf %llu, data list "
1347 "%#llx\n", root_node->val, ref_node->val,
1348 ref_node->aux);
1349 ret = iterate_leaf_refs((struct extent_inode_elem *)
1350 (uintptr_t)ref_node->aux,
1351 root_node->val,
1352 extent_item_objectid,
1353 iterate, ctx);
1354 }
1355 ulist_free(roots);
1356 }
1357
1358 free_leaf_list(refs);
1359 out:
1360 return ret;
1361 }
1362
1363 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1364 struct btrfs_path *path,
1365 iterate_extent_inodes_t *iterate, void *ctx)
1366 {
1367 int ret;
1368 u64 extent_item_pos;
1369 u64 flags = 0;
1370 struct btrfs_key found_key;
1371 int search_commit_root = 0;
1372
1373 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1374 btrfs_release_path(path);
1375 if (ret < 0)
1376 return ret;
1377 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1378 return -EINVAL;
1379
1380 extent_item_pos = logical - found_key.objectid;
1381 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1382 extent_item_pos, search_commit_root,
1383 iterate, ctx);
1384
1385 return ret;
1386 }
1387
1388 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1389 struct extent_buffer *eb, void *ctx);
1390
1391 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1392 struct btrfs_path *path,
1393 iterate_irefs_t *iterate, void *ctx)
1394 {
1395 int ret = 0;
1396 int slot;
1397 u32 cur;
1398 u32 len;
1399 u32 name_len;
1400 u64 parent = 0;
1401 int found = 0;
1402 struct extent_buffer *eb;
1403 struct btrfs_item *item;
1404 struct btrfs_inode_ref *iref;
1405 struct btrfs_key found_key;
1406
1407 while (!ret) {
1408 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1409 &found_key);
1410 if (ret < 0)
1411 break;
1412 if (ret) {
1413 ret = found ? 0 : -ENOENT;
1414 break;
1415 }
1416 ++found;
1417
1418 parent = found_key.offset;
1419 slot = path->slots[0];
1420 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1421 if (!eb) {
1422 ret = -ENOMEM;
1423 break;
1424 }
1425 extent_buffer_get(eb);
1426 btrfs_release_path(path);
1427
1428 item = btrfs_item_nr(slot);
1429 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1430
1431 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1432 name_len = btrfs_inode_ref_name_len(eb, iref);
1433 /* path must be released before calling iterate()! */
1434 pr_debug("following ref at offset %u for inode %llu in "
1435 "tree %llu\n", cur, found_key.objectid,
1436 fs_root->objectid);
1437 ret = iterate(parent, name_len,
1438 (unsigned long)(iref + 1), eb, ctx);
1439 if (ret)
1440 break;
1441 len = sizeof(*iref) + name_len;
1442 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1443 }
1444 free_extent_buffer(eb);
1445 }
1446
1447 btrfs_release_path(path);
1448
1449 return ret;
1450 }
1451
1452 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1453 struct btrfs_path *path,
1454 iterate_irefs_t *iterate, void *ctx)
1455 {
1456 int ret;
1457 int slot;
1458 u64 offset = 0;
1459 u64 parent;
1460 int found = 0;
1461 struct extent_buffer *eb;
1462 struct btrfs_inode_extref *extref;
1463 struct extent_buffer *leaf;
1464 u32 item_size;
1465 u32 cur_offset;
1466 unsigned long ptr;
1467
1468 while (1) {
1469 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1470 &offset);
1471 if (ret < 0)
1472 break;
1473 if (ret) {
1474 ret = found ? 0 : -ENOENT;
1475 break;
1476 }
1477 ++found;
1478
1479 slot = path->slots[0];
1480 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1481 if (!eb) {
1482 ret = -ENOMEM;
1483 break;
1484 }
1485 extent_buffer_get(eb);
1486
1487 btrfs_release_path(path);
1488
1489 leaf = path->nodes[0];
1490 item_size = btrfs_item_size_nr(leaf, slot);
1491 ptr = btrfs_item_ptr_offset(leaf, slot);
1492 cur_offset = 0;
1493
1494 while (cur_offset < item_size) {
1495 u32 name_len;
1496
1497 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1498 parent = btrfs_inode_extref_parent(eb, extref);
1499 name_len = btrfs_inode_extref_name_len(eb, extref);
1500 ret = iterate(parent, name_len,
1501 (unsigned long)&extref->name, eb, ctx);
1502 if (ret)
1503 break;
1504
1505 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1506 cur_offset += sizeof(*extref);
1507 }
1508 free_extent_buffer(eb);
1509
1510 offset++;
1511 }
1512
1513 btrfs_release_path(path);
1514
1515 return ret;
1516 }
1517
1518 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1519 struct btrfs_path *path, iterate_irefs_t *iterate,
1520 void *ctx)
1521 {
1522 int ret;
1523 int found_refs = 0;
1524
1525 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1526 if (!ret)
1527 ++found_refs;
1528 else if (ret != -ENOENT)
1529 return ret;
1530
1531 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1532 if (ret == -ENOENT && found_refs)
1533 return 0;
1534
1535 return ret;
1536 }
1537
1538 /*
1539 * returns 0 if the path could be dumped (probably truncated)
1540 * returns <0 in case of an error
1541 */
1542 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1543 struct extent_buffer *eb, void *ctx)
1544 {
1545 struct inode_fs_paths *ipath = ctx;
1546 char *fspath;
1547 char *fspath_min;
1548 int i = ipath->fspath->elem_cnt;
1549 const int s_ptr = sizeof(char *);
1550 u32 bytes_left;
1551
1552 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1553 ipath->fspath->bytes_left - s_ptr : 0;
1554
1555 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1556 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1557 name_off, eb, inum, fspath_min, bytes_left);
1558 if (IS_ERR(fspath))
1559 return PTR_ERR(fspath);
1560
1561 if (fspath > fspath_min) {
1562 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1563 ++ipath->fspath->elem_cnt;
1564 ipath->fspath->bytes_left = fspath - fspath_min;
1565 } else {
1566 ++ipath->fspath->elem_missed;
1567 ipath->fspath->bytes_missing += fspath_min - fspath;
1568 ipath->fspath->bytes_left = 0;
1569 }
1570
1571 return 0;
1572 }
1573
1574 /*
1575 * this dumps all file system paths to the inode into the ipath struct, provided
1576 * is has been created large enough. each path is zero-terminated and accessed
1577 * from ipath->fspath->val[i].
1578 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1579 * in ipath->fspath->val[]. When the allocated space wasn't sufficient, the
1580 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
1581 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1582 * have been needed to return all paths.
1583 */
1584 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1585 {
1586 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1587 inode_to_path, ipath);
1588 }
1589
1590 struct btrfs_data_container *init_data_container(u32 total_bytes)
1591 {
1592 struct btrfs_data_container *data;
1593 size_t alloc_bytes;
1594
1595 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1596 data = vmalloc(alloc_bytes);
1597 if (!data)
1598 return ERR_PTR(-ENOMEM);
1599
1600 if (total_bytes >= sizeof(*data)) {
1601 data->bytes_left = total_bytes - sizeof(*data);
1602 data->bytes_missing = 0;
1603 } else {
1604 data->bytes_missing = sizeof(*data) - total_bytes;
1605 data->bytes_left = 0;
1606 }
1607
1608 data->elem_cnt = 0;
1609 data->elem_missed = 0;
1610
1611 return data;
1612 }
1613
1614 /*
1615 * allocates space to return multiple file system paths for an inode.
1616 * total_bytes to allocate are passed, note that space usable for actual path
1617 * information will be total_bytes - sizeof(struct inode_fs_paths).
1618 * the returned pointer must be freed with free_ipath() in the end.
1619 */
1620 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1621 struct btrfs_path *path)
1622 {
1623 struct inode_fs_paths *ifp;
1624 struct btrfs_data_container *fspath;
1625
1626 fspath = init_data_container(total_bytes);
1627 if (IS_ERR(fspath))
1628 return (void *)fspath;
1629
1630 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1631 if (!ifp) {
1632 kfree(fspath);
1633 return ERR_PTR(-ENOMEM);
1634 }
1635
1636 ifp->btrfs_path = path;
1637 ifp->fspath = fspath;
1638 ifp->fs_root = fs_root;
1639
1640 return ifp;
1641 }
1642
1643 void free_ipath(struct inode_fs_paths *ipath)
1644 {
1645 if (!ipath)
1646 return;
1647 vfree(ipath->fspath);
1648 kfree(ipath);
1649 }
(deprecated) Btrfs progs developments and patch integration