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Merge tag 'for-linus-v3.10-rc3' of git://oss.sgi.com/xfs/xfs
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / btrfs / backref.c
1 /*
2 * Copyright (C) 2011 STRATO. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/vmalloc.h>
20 #include "ctree.h"
21 #include "disk-io.h"
22 #include "backref.h"
23 #include "ulist.h"
24 #include "transaction.h"
25 #include "delayed-ref.h"
26 #include "locking.h"
27
28 struct extent_inode_elem {
29 u64 inum;
30 u64 offset;
31 struct extent_inode_elem *next;
32 };
33
34 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
35 struct btrfs_file_extent_item *fi,
36 u64 extent_item_pos,
37 struct extent_inode_elem **eie)
38 {
39 u64 data_offset;
40 u64 data_len;
41 struct extent_inode_elem *e;
42
43 data_offset = btrfs_file_extent_offset(eb, fi);
44 data_len = btrfs_file_extent_num_bytes(eb, fi);
45
46 if (extent_item_pos < data_offset ||
47 extent_item_pos >= data_offset + data_len)
48 return 1;
49
50 e = kmalloc(sizeof(*e), GFP_NOFS);
51 if (!e)
52 return -ENOMEM;
53
54 e->next = *eie;
55 e->inum = key->objectid;
56 e->offset = key->offset + (extent_item_pos - data_offset);
57 *eie = e;
58
59 return 0;
60 }
61
62 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
63 u64 extent_item_pos,
64 struct extent_inode_elem **eie)
65 {
66 u64 disk_byte;
67 struct btrfs_key key;
68 struct btrfs_file_extent_item *fi;
69 int slot;
70 int nritems;
71 int extent_type;
72 int ret;
73
74 /*
75 * from the shared data ref, we only have the leaf but we need
76 * the key. thus, we must look into all items and see that we
77 * find one (some) with a reference to our extent item.
78 */
79 nritems = btrfs_header_nritems(eb);
80 for (slot = 0; slot < nritems; ++slot) {
81 btrfs_item_key_to_cpu(eb, &key, slot);
82 if (key.type != BTRFS_EXTENT_DATA_KEY)
83 continue;
84 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
85 extent_type = btrfs_file_extent_type(eb, fi);
86 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
87 continue;
88 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
89 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
90 if (disk_byte != wanted_disk_byte)
91 continue;
92
93 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
94 if (ret < 0)
95 return ret;
96 }
97
98 return 0;
99 }
100
101 /*
102 * this structure records all encountered refs on the way up to the root
103 */
104 struct __prelim_ref {
105 struct list_head list;
106 u64 root_id;
107 struct btrfs_key key_for_search;
108 int level;
109 int count;
110 struct extent_inode_elem *inode_list;
111 u64 parent;
112 u64 wanted_disk_byte;
113 };
114
115 /*
116 * the rules for all callers of this function are:
117 * - obtaining the parent is the goal
118 * - if you add a key, you must know that it is a correct key
119 * - if you cannot add the parent or a correct key, then we will look into the
120 * block later to set a correct key
121 *
122 * delayed refs
123 * ============
124 * backref type | shared | indirect | shared | indirect
125 * information | tree | tree | data | data
126 * --------------------+--------+----------+--------+----------
127 * parent logical | y | - | - | -
128 * key to resolve | - | y | y | y
129 * tree block logical | - | - | - | -
130 * root for resolving | y | y | y | y
131 *
132 * - column 1: we've the parent -> done
133 * - column 2, 3, 4: we use the key to find the parent
134 *
135 * on disk refs (inline or keyed)
136 * ==============================
137 * backref type | shared | indirect | shared | indirect
138 * information | tree | tree | data | data
139 * --------------------+--------+----------+--------+----------
140 * parent logical | y | - | y | -
141 * key to resolve | - | - | - | y
142 * tree block logical | y | y | y | y
143 * root for resolving | - | y | y | y
144 *
145 * - column 1, 3: we've the parent -> done
146 * - column 2: we take the first key from the block to find the parent
147 * (see __add_missing_keys)
148 * - column 4: we use the key to find the parent
149 *
150 * additional information that's available but not required to find the parent
151 * block might help in merging entries to gain some speed.
152 */
153
154 static int __add_prelim_ref(struct list_head *head, u64 root_id,
155 struct btrfs_key *key, int level,
156 u64 parent, u64 wanted_disk_byte, int count)
157 {
158 struct __prelim_ref *ref;
159
160 /* in case we're adding delayed refs, we're holding the refs spinlock */
161 ref = kmalloc(sizeof(*ref), GFP_ATOMIC);
162 if (!ref)
163 return -ENOMEM;
164
165 ref->root_id = root_id;
166 if (key)
167 ref->key_for_search = *key;
168 else
169 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
170
171 ref->inode_list = NULL;
172 ref->level = level;
173 ref->count = count;
174 ref->parent = parent;
175 ref->wanted_disk_byte = wanted_disk_byte;
176 list_add_tail(&ref->list, head);
177
178 return 0;
179 }
180
181 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
182 struct ulist *parents, int level,
183 struct btrfs_key *key_for_search, u64 time_seq,
184 u64 wanted_disk_byte,
185 const u64 *extent_item_pos)
186 {
187 int ret = 0;
188 int slot;
189 struct extent_buffer *eb;
190 struct btrfs_key key;
191 struct btrfs_file_extent_item *fi;
192 struct extent_inode_elem *eie = NULL;
193 u64 disk_byte;
194
195 if (level != 0) {
196 eb = path->nodes[level];
197 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
198 if (ret < 0)
199 return ret;
200 return 0;
201 }
202
203 /*
204 * We normally enter this function with the path already pointing to
205 * the first item to check. But sometimes, we may enter it with
206 * slot==nritems. In that case, go to the next leaf before we continue.
207 */
208 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
209 ret = btrfs_next_old_leaf(root, path, time_seq);
210
211 while (!ret) {
212 eb = path->nodes[0];
213 slot = path->slots[0];
214
215 btrfs_item_key_to_cpu(eb, &key, slot);
216
217 if (key.objectid != key_for_search->objectid ||
218 key.type != BTRFS_EXTENT_DATA_KEY)
219 break;
220
221 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
222 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
223
224 if (disk_byte == wanted_disk_byte) {
225 eie = NULL;
226 if (extent_item_pos) {
227 ret = check_extent_in_eb(&key, eb, fi,
228 *extent_item_pos,
229 &eie);
230 if (ret < 0)
231 break;
232 }
233 if (!ret) {
234 ret = ulist_add(parents, eb->start,
235 (uintptr_t)eie, GFP_NOFS);
236 if (ret < 0)
237 break;
238 if (!extent_item_pos) {
239 ret = btrfs_next_old_leaf(root, path,
240 time_seq);
241 continue;
242 }
243 }
244 }
245 ret = btrfs_next_old_item(root, path, time_seq);
246 }
247
248 if (ret > 0)
249 ret = 0;
250 return ret;
251 }
252
253 /*
254 * resolve an indirect backref in the form (root_id, key, level)
255 * to a logical address
256 */
257 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
258 int search_commit_root,
259 u64 time_seq,
260 struct __prelim_ref *ref,
261 struct ulist *parents,
262 const u64 *extent_item_pos)
263 {
264 struct btrfs_path *path;
265 struct btrfs_root *root;
266 struct btrfs_key root_key;
267 struct extent_buffer *eb;
268 int ret = 0;
269 int root_level;
270 int level = ref->level;
271
272 path = btrfs_alloc_path();
273 if (!path)
274 return -ENOMEM;
275 path->search_commit_root = !!search_commit_root;
276
277 root_key.objectid = ref->root_id;
278 root_key.type = BTRFS_ROOT_ITEM_KEY;
279 root_key.offset = (u64)-1;
280 root = btrfs_read_fs_root_no_name(fs_info, &root_key);
281 if (IS_ERR(root)) {
282 ret = PTR_ERR(root);
283 goto out;
284 }
285
286 root_level = btrfs_old_root_level(root, time_seq);
287
288 if (root_level + 1 == level)
289 goto out;
290
291 path->lowest_level = level;
292 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
293 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
294 "%d for key (%llu %u %llu)\n",
295 (unsigned long long)ref->root_id, level, ref->count, ret,
296 (unsigned long long)ref->key_for_search.objectid,
297 ref->key_for_search.type,
298 (unsigned long long)ref->key_for_search.offset);
299 if (ret < 0)
300 goto out;
301
302 eb = path->nodes[level];
303 while (!eb) {
304 if (!level) {
305 WARN_ON(1);
306 ret = 1;
307 goto out;
308 }
309 level--;
310 eb = path->nodes[level];
311 }
312
313 ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
314 time_seq, ref->wanted_disk_byte,
315 extent_item_pos);
316 out:
317 btrfs_free_path(path);
318 return ret;
319 }
320
321 /*
322 * resolve all indirect backrefs from the list
323 */
324 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
325 int search_commit_root, u64 time_seq,
326 struct list_head *head,
327 const u64 *extent_item_pos)
328 {
329 int err;
330 int ret = 0;
331 struct __prelim_ref *ref;
332 struct __prelim_ref *ref_safe;
333 struct __prelim_ref *new_ref;
334 struct ulist *parents;
335 struct ulist_node *node;
336 struct ulist_iterator uiter;
337
338 parents = ulist_alloc(GFP_NOFS);
339 if (!parents)
340 return -ENOMEM;
341
342 /*
343 * _safe allows us to insert directly after the current item without
344 * iterating over the newly inserted items.
345 * we're also allowed to re-assign ref during iteration.
346 */
347 list_for_each_entry_safe(ref, ref_safe, head, list) {
348 if (ref->parent) /* already direct */
349 continue;
350 if (ref->count == 0)
351 continue;
352 err = __resolve_indirect_ref(fs_info, search_commit_root,
353 time_seq, ref, parents,
354 extent_item_pos);
355 if (err == -ENOMEM)
356 goto out;
357 if (err)
358 continue;
359
360 /* we put the first parent into the ref at hand */
361 ULIST_ITER_INIT(&uiter);
362 node = ulist_next(parents, &uiter);
363 ref->parent = node ? node->val : 0;
364 ref->inode_list = node ?
365 (struct extent_inode_elem *)(uintptr_t)node->aux : 0;
366
367 /* additional parents require new refs being added here */
368 while ((node = ulist_next(parents, &uiter))) {
369 new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
370 if (!new_ref) {
371 ret = -ENOMEM;
372 goto out;
373 }
374 memcpy(new_ref, ref, sizeof(*ref));
375 new_ref->parent = node->val;
376 new_ref->inode_list = (struct extent_inode_elem *)
377 (uintptr_t)node->aux;
378 list_add(&new_ref->list, &ref->list);
379 }
380 ulist_reinit(parents);
381 }
382 out:
383 ulist_free(parents);
384 return ret;
385 }
386
387 static inline int ref_for_same_block(struct __prelim_ref *ref1,
388 struct __prelim_ref *ref2)
389 {
390 if (ref1->level != ref2->level)
391 return 0;
392 if (ref1->root_id != ref2->root_id)
393 return 0;
394 if (ref1->key_for_search.type != ref2->key_for_search.type)
395 return 0;
396 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
397 return 0;
398 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
399 return 0;
400 if (ref1->parent != ref2->parent)
401 return 0;
402
403 return 1;
404 }
405
406 /*
407 * read tree blocks and add keys where required.
408 */
409 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
410 struct list_head *head)
411 {
412 struct list_head *pos;
413 struct extent_buffer *eb;
414
415 list_for_each(pos, head) {
416 struct __prelim_ref *ref;
417 ref = list_entry(pos, struct __prelim_ref, list);
418
419 if (ref->parent)
420 continue;
421 if (ref->key_for_search.type)
422 continue;
423 BUG_ON(!ref->wanted_disk_byte);
424 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
425 fs_info->tree_root->leafsize, 0);
426 if (!eb || !extent_buffer_uptodate(eb)) {
427 free_extent_buffer(eb);
428 return -EIO;
429 }
430 btrfs_tree_read_lock(eb);
431 if (btrfs_header_level(eb) == 0)
432 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
433 else
434 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
435 btrfs_tree_read_unlock(eb);
436 free_extent_buffer(eb);
437 }
438 return 0;
439 }
440
441 /*
442 * merge two lists of backrefs and adjust counts accordingly
443 *
444 * mode = 1: merge identical keys, if key is set
445 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
446 * additionally, we could even add a key range for the blocks we
447 * looked into to merge even more (-> replace unresolved refs by those
448 * having a parent).
449 * mode = 2: merge identical parents
450 */
451 static void __merge_refs(struct list_head *head, int mode)
452 {
453 struct list_head *pos1;
454
455 list_for_each(pos1, head) {
456 struct list_head *n2;
457 struct list_head *pos2;
458 struct __prelim_ref *ref1;
459
460 ref1 = list_entry(pos1, struct __prelim_ref, list);
461
462 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
463 pos2 = n2, n2 = pos2->next) {
464 struct __prelim_ref *ref2;
465 struct __prelim_ref *xchg;
466 struct extent_inode_elem *eie;
467
468 ref2 = list_entry(pos2, struct __prelim_ref, list);
469
470 if (mode == 1) {
471 if (!ref_for_same_block(ref1, ref2))
472 continue;
473 if (!ref1->parent && ref2->parent) {
474 xchg = ref1;
475 ref1 = ref2;
476 ref2 = xchg;
477 }
478 } else {
479 if (ref1->parent != ref2->parent)
480 continue;
481 }
482
483 eie = ref1->inode_list;
484 while (eie && eie->next)
485 eie = eie->next;
486 if (eie)
487 eie->next = ref2->inode_list;
488 else
489 ref1->inode_list = ref2->inode_list;
490 ref1->count += ref2->count;
491
492 list_del(&ref2->list);
493 kfree(ref2);
494 }
495
496 }
497 }
498
499 /*
500 * add all currently queued delayed refs from this head whose seq nr is
501 * smaller or equal that seq to the list
502 */
503 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
504 struct list_head *prefs)
505 {
506 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
507 struct rb_node *n = &head->node.rb_node;
508 struct btrfs_key key;
509 struct btrfs_key op_key = {0};
510 int sgn;
511 int ret = 0;
512
513 if (extent_op && extent_op->update_key)
514 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
515
516 while ((n = rb_prev(n))) {
517 struct btrfs_delayed_ref_node *node;
518 node = rb_entry(n, struct btrfs_delayed_ref_node,
519 rb_node);
520 if (node->bytenr != head->node.bytenr)
521 break;
522 WARN_ON(node->is_head);
523
524 if (node->seq > seq)
525 continue;
526
527 switch (node->action) {
528 case BTRFS_ADD_DELAYED_EXTENT:
529 case BTRFS_UPDATE_DELAYED_HEAD:
530 WARN_ON(1);
531 continue;
532 case BTRFS_ADD_DELAYED_REF:
533 sgn = 1;
534 break;
535 case BTRFS_DROP_DELAYED_REF:
536 sgn = -1;
537 break;
538 default:
539 BUG_ON(1);
540 }
541 switch (node->type) {
542 case BTRFS_TREE_BLOCK_REF_KEY: {
543 struct btrfs_delayed_tree_ref *ref;
544
545 ref = btrfs_delayed_node_to_tree_ref(node);
546 ret = __add_prelim_ref(prefs, ref->root, &op_key,
547 ref->level + 1, 0, node->bytenr,
548 node->ref_mod * sgn);
549 break;
550 }
551 case BTRFS_SHARED_BLOCK_REF_KEY: {
552 struct btrfs_delayed_tree_ref *ref;
553
554 ref = btrfs_delayed_node_to_tree_ref(node);
555 ret = __add_prelim_ref(prefs, ref->root, NULL,
556 ref->level + 1, ref->parent,
557 node->bytenr,
558 node->ref_mod * sgn);
559 break;
560 }
561 case BTRFS_EXTENT_DATA_REF_KEY: {
562 struct btrfs_delayed_data_ref *ref;
563 ref = btrfs_delayed_node_to_data_ref(node);
564
565 key.objectid = ref->objectid;
566 key.type = BTRFS_EXTENT_DATA_KEY;
567 key.offset = ref->offset;
568 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
569 node->bytenr,
570 node->ref_mod * sgn);
571 break;
572 }
573 case BTRFS_SHARED_DATA_REF_KEY: {
574 struct btrfs_delayed_data_ref *ref;
575
576 ref = btrfs_delayed_node_to_data_ref(node);
577
578 key.objectid = ref->objectid;
579 key.type = BTRFS_EXTENT_DATA_KEY;
580 key.offset = ref->offset;
581 ret = __add_prelim_ref(prefs, ref->root, &key, 0,
582 ref->parent, node->bytenr,
583 node->ref_mod * sgn);
584 break;
585 }
586 default:
587 WARN_ON(1);
588 }
589 if (ret)
590 return ret;
591 }
592
593 return 0;
594 }
595
596 /*
597 * add all inline backrefs for bytenr to the list
598 */
599 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
600 struct btrfs_path *path, u64 bytenr,
601 int *info_level, struct list_head *prefs)
602 {
603 int ret = 0;
604 int slot;
605 struct extent_buffer *leaf;
606 struct btrfs_key key;
607 unsigned long ptr;
608 unsigned long end;
609 struct btrfs_extent_item *ei;
610 u64 flags;
611 u64 item_size;
612
613 /*
614 * enumerate all inline refs
615 */
616 leaf = path->nodes[0];
617 slot = path->slots[0];
618
619 item_size = btrfs_item_size_nr(leaf, slot);
620 BUG_ON(item_size < sizeof(*ei));
621
622 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
623 flags = btrfs_extent_flags(leaf, ei);
624
625 ptr = (unsigned long)(ei + 1);
626 end = (unsigned long)ei + item_size;
627
628 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
629 struct btrfs_tree_block_info *info;
630
631 info = (struct btrfs_tree_block_info *)ptr;
632 *info_level = btrfs_tree_block_level(leaf, info);
633 ptr += sizeof(struct btrfs_tree_block_info);
634 BUG_ON(ptr > end);
635 } else {
636 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
637 }
638
639 while (ptr < end) {
640 struct btrfs_extent_inline_ref *iref;
641 u64 offset;
642 int type;
643
644 iref = (struct btrfs_extent_inline_ref *)ptr;
645 type = btrfs_extent_inline_ref_type(leaf, iref);
646 offset = btrfs_extent_inline_ref_offset(leaf, iref);
647
648 switch (type) {
649 case BTRFS_SHARED_BLOCK_REF_KEY:
650 ret = __add_prelim_ref(prefs, 0, NULL,
651 *info_level + 1, offset,
652 bytenr, 1);
653 break;
654 case BTRFS_SHARED_DATA_REF_KEY: {
655 struct btrfs_shared_data_ref *sdref;
656 int count;
657
658 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
659 count = btrfs_shared_data_ref_count(leaf, sdref);
660 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
661 bytenr, count);
662 break;
663 }
664 case BTRFS_TREE_BLOCK_REF_KEY:
665 ret = __add_prelim_ref(prefs, offset, NULL,
666 *info_level + 1, 0,
667 bytenr, 1);
668 break;
669 case BTRFS_EXTENT_DATA_REF_KEY: {
670 struct btrfs_extent_data_ref *dref;
671 int count;
672 u64 root;
673
674 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
675 count = btrfs_extent_data_ref_count(leaf, dref);
676 key.objectid = btrfs_extent_data_ref_objectid(leaf,
677 dref);
678 key.type = BTRFS_EXTENT_DATA_KEY;
679 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
680 root = btrfs_extent_data_ref_root(leaf, dref);
681 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
682 bytenr, count);
683 break;
684 }
685 default:
686 WARN_ON(1);
687 }
688 if (ret)
689 return ret;
690 ptr += btrfs_extent_inline_ref_size(type);
691 }
692
693 return 0;
694 }
695
696 /*
697 * add all non-inline backrefs for bytenr to the list
698 */
699 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
700 struct btrfs_path *path, u64 bytenr,
701 int info_level, struct list_head *prefs)
702 {
703 struct btrfs_root *extent_root = fs_info->extent_root;
704 int ret;
705 int slot;
706 struct extent_buffer *leaf;
707 struct btrfs_key key;
708
709 while (1) {
710 ret = btrfs_next_item(extent_root, path);
711 if (ret < 0)
712 break;
713 if (ret) {
714 ret = 0;
715 break;
716 }
717
718 slot = path->slots[0];
719 leaf = path->nodes[0];
720 btrfs_item_key_to_cpu(leaf, &key, slot);
721
722 if (key.objectid != bytenr)
723 break;
724 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
725 continue;
726 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
727 break;
728
729 switch (key.type) {
730 case BTRFS_SHARED_BLOCK_REF_KEY:
731 ret = __add_prelim_ref(prefs, 0, NULL,
732 info_level + 1, key.offset,
733 bytenr, 1);
734 break;
735 case BTRFS_SHARED_DATA_REF_KEY: {
736 struct btrfs_shared_data_ref *sdref;
737 int count;
738
739 sdref = btrfs_item_ptr(leaf, slot,
740 struct btrfs_shared_data_ref);
741 count = btrfs_shared_data_ref_count(leaf, sdref);
742 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
743 bytenr, count);
744 break;
745 }
746 case BTRFS_TREE_BLOCK_REF_KEY:
747 ret = __add_prelim_ref(prefs, key.offset, NULL,
748 info_level + 1, 0,
749 bytenr, 1);
750 break;
751 case BTRFS_EXTENT_DATA_REF_KEY: {
752 struct btrfs_extent_data_ref *dref;
753 int count;
754 u64 root;
755
756 dref = btrfs_item_ptr(leaf, slot,
757 struct btrfs_extent_data_ref);
758 count = btrfs_extent_data_ref_count(leaf, dref);
759 key.objectid = btrfs_extent_data_ref_objectid(leaf,
760 dref);
761 key.type = BTRFS_EXTENT_DATA_KEY;
762 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
763 root = btrfs_extent_data_ref_root(leaf, dref);
764 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
765 bytenr, count);
766 break;
767 }
768 default:
769 WARN_ON(1);
770 }
771 if (ret)
772 return ret;
773
774 }
775
776 return ret;
777 }
778
779 /*
780 * this adds all existing backrefs (inline backrefs, backrefs and delayed
781 * refs) for the given bytenr to the refs list, merges duplicates and resolves
782 * indirect refs to their parent bytenr.
783 * When roots are found, they're added to the roots list
784 *
785 * FIXME some caching might speed things up
786 */
787 static int find_parent_nodes(struct btrfs_trans_handle *trans,
788 struct btrfs_fs_info *fs_info, u64 bytenr,
789 u64 time_seq, struct ulist *refs,
790 struct ulist *roots, const u64 *extent_item_pos)
791 {
792 struct btrfs_key key;
793 struct btrfs_path *path;
794 struct btrfs_delayed_ref_root *delayed_refs = NULL;
795 struct btrfs_delayed_ref_head *head;
796 int info_level = 0;
797 int ret;
798 int search_commit_root = (trans == BTRFS_BACKREF_SEARCH_COMMIT_ROOT);
799 struct list_head prefs_delayed;
800 struct list_head prefs;
801 struct __prelim_ref *ref;
802
803 INIT_LIST_HEAD(&prefs);
804 INIT_LIST_HEAD(&prefs_delayed);
805
806 key.objectid = bytenr;
807 key.type = BTRFS_EXTENT_ITEM_KEY;
808 key.offset = (u64)-1;
809
810 path = btrfs_alloc_path();
811 if (!path)
812 return -ENOMEM;
813 path->search_commit_root = !!search_commit_root;
814
815 /*
816 * grab both a lock on the path and a lock on the delayed ref head.
817 * We need both to get a consistent picture of how the refs look
818 * at a specified point in time
819 */
820 again:
821 head = NULL;
822
823 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
824 if (ret < 0)
825 goto out;
826 BUG_ON(ret == 0);
827
828 if (trans != BTRFS_BACKREF_SEARCH_COMMIT_ROOT) {
829 /*
830 * look if there are updates for this ref queued and lock the
831 * head
832 */
833 delayed_refs = &trans->transaction->delayed_refs;
834 spin_lock(&delayed_refs->lock);
835 head = btrfs_find_delayed_ref_head(trans, bytenr);
836 if (head) {
837 if (!mutex_trylock(&head->mutex)) {
838 atomic_inc(&head->node.refs);
839 spin_unlock(&delayed_refs->lock);
840
841 btrfs_release_path(path);
842
843 /*
844 * Mutex was contended, block until it's
845 * released and try again
846 */
847 mutex_lock(&head->mutex);
848 mutex_unlock(&head->mutex);
849 btrfs_put_delayed_ref(&head->node);
850 goto again;
851 }
852 ret = __add_delayed_refs(head, time_seq,
853 &prefs_delayed);
854 mutex_unlock(&head->mutex);
855 if (ret) {
856 spin_unlock(&delayed_refs->lock);
857 goto out;
858 }
859 }
860 spin_unlock(&delayed_refs->lock);
861 }
862
863 if (path->slots[0]) {
864 struct extent_buffer *leaf;
865 int slot;
866
867 path->slots[0]--;
868 leaf = path->nodes[0];
869 slot = path->slots[0];
870 btrfs_item_key_to_cpu(leaf, &key, slot);
871 if (key.objectid == bytenr &&
872 key.type == BTRFS_EXTENT_ITEM_KEY) {
873 ret = __add_inline_refs(fs_info, path, bytenr,
874 &info_level, &prefs);
875 if (ret)
876 goto out;
877 ret = __add_keyed_refs(fs_info, path, bytenr,
878 info_level, &prefs);
879 if (ret)
880 goto out;
881 }
882 }
883 btrfs_release_path(path);
884
885 list_splice_init(&prefs_delayed, &prefs);
886
887 ret = __add_missing_keys(fs_info, &prefs);
888 if (ret)
889 goto out;
890
891 __merge_refs(&prefs, 1);
892
893 ret = __resolve_indirect_refs(fs_info, search_commit_root, time_seq,
894 &prefs, extent_item_pos);
895 if (ret)
896 goto out;
897
898 __merge_refs(&prefs, 2);
899
900 while (!list_empty(&prefs)) {
901 ref = list_first_entry(&prefs, struct __prelim_ref, list);
902 list_del(&ref->list);
903 WARN_ON(ref->count < 0);
904 if (ref->count && ref->root_id && ref->parent == 0) {
905 /* no parent == root of tree */
906 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
907 if (ret < 0)
908 goto out;
909 }
910 if (ref->count && ref->parent) {
911 struct extent_inode_elem *eie = NULL;
912 if (extent_item_pos && !ref->inode_list) {
913 u32 bsz;
914 struct extent_buffer *eb;
915 bsz = btrfs_level_size(fs_info->extent_root,
916 info_level);
917 eb = read_tree_block(fs_info->extent_root,
918 ref->parent, bsz, 0);
919 if (!eb || !extent_buffer_uptodate(eb)) {
920 free_extent_buffer(eb);
921 ret = -EIO;
922 goto out;
923 }
924 ret = find_extent_in_eb(eb, bytenr,
925 *extent_item_pos, &eie);
926 ref->inode_list = eie;
927 free_extent_buffer(eb);
928 }
929 ret = ulist_add_merge(refs, ref->parent,
930 (uintptr_t)ref->inode_list,
931 (u64 *)&eie, GFP_NOFS);
932 if (ret < 0)
933 goto out;
934 if (!ret && extent_item_pos) {
935 /*
936 * we've recorded that parent, so we must extend
937 * its inode list here
938 */
939 BUG_ON(!eie);
940 while (eie->next)
941 eie = eie->next;
942 eie->next = ref->inode_list;
943 }
944 }
945 kfree(ref);
946 }
947
948 out:
949 btrfs_free_path(path);
950 while (!list_empty(&prefs)) {
951 ref = list_first_entry(&prefs, struct __prelim_ref, list);
952 list_del(&ref->list);
953 kfree(ref);
954 }
955 while (!list_empty(&prefs_delayed)) {
956 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
957 list);
958 list_del(&ref->list);
959 kfree(ref);
960 }
961
962 return ret;
963 }
964
965 static void free_leaf_list(struct ulist *blocks)
966 {
967 struct ulist_node *node = NULL;
968 struct extent_inode_elem *eie;
969 struct extent_inode_elem *eie_next;
970 struct ulist_iterator uiter;
971
972 ULIST_ITER_INIT(&uiter);
973 while ((node = ulist_next(blocks, &uiter))) {
974 if (!node->aux)
975 continue;
976 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
977 for (; eie; eie = eie_next) {
978 eie_next = eie->next;
979 kfree(eie);
980 }
981 node->aux = 0;
982 }
983
984 ulist_free(blocks);
985 }
986
987 /*
988 * Finds all leafs with a reference to the specified combination of bytenr and
989 * offset. key_list_head will point to a list of corresponding keys (caller must
990 * free each list element). The leafs will be stored in the leafs ulist, which
991 * must be freed with ulist_free.
992 *
993 * returns 0 on success, <0 on error
994 */
995 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
996 struct btrfs_fs_info *fs_info, u64 bytenr,
997 u64 time_seq, struct ulist **leafs,
998 const u64 *extent_item_pos)
999 {
1000 struct ulist *tmp;
1001 int ret;
1002
1003 tmp = ulist_alloc(GFP_NOFS);
1004 if (!tmp)
1005 return -ENOMEM;
1006 *leafs = ulist_alloc(GFP_NOFS);
1007 if (!*leafs) {
1008 ulist_free(tmp);
1009 return -ENOMEM;
1010 }
1011
1012 ret = find_parent_nodes(trans, fs_info, bytenr,
1013 time_seq, *leafs, tmp, extent_item_pos);
1014 ulist_free(tmp);
1015
1016 if (ret < 0 && ret != -ENOENT) {
1017 free_leaf_list(*leafs);
1018 return ret;
1019 }
1020
1021 return 0;
1022 }
1023
1024 /*
1025 * walk all backrefs for a given extent to find all roots that reference this
1026 * extent. Walking a backref means finding all extents that reference this
1027 * extent and in turn walk the backrefs of those, too. Naturally this is a
1028 * recursive process, but here it is implemented in an iterative fashion: We
1029 * find all referencing extents for the extent in question and put them on a
1030 * list. In turn, we find all referencing extents for those, further appending
1031 * to the list. The way we iterate the list allows adding more elements after
1032 * the current while iterating. The process stops when we reach the end of the
1033 * list. Found roots are added to the roots list.
1034 *
1035 * returns 0 on success, < 0 on error.
1036 */
1037 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1038 struct btrfs_fs_info *fs_info, u64 bytenr,
1039 u64 time_seq, struct ulist **roots)
1040 {
1041 struct ulist *tmp;
1042 struct ulist_node *node = NULL;
1043 struct ulist_iterator uiter;
1044 int ret;
1045
1046 tmp = ulist_alloc(GFP_NOFS);
1047 if (!tmp)
1048 return -ENOMEM;
1049 *roots = ulist_alloc(GFP_NOFS);
1050 if (!*roots) {
1051 ulist_free(tmp);
1052 return -ENOMEM;
1053 }
1054
1055 ULIST_ITER_INIT(&uiter);
1056 while (1) {
1057 ret = find_parent_nodes(trans, fs_info, bytenr,
1058 time_seq, tmp, *roots, NULL);
1059 if (ret < 0 && ret != -ENOENT) {
1060 ulist_free(tmp);
1061 ulist_free(*roots);
1062 return ret;
1063 }
1064 node = ulist_next(tmp, &uiter);
1065 if (!node)
1066 break;
1067 bytenr = node->val;
1068 }
1069
1070 ulist_free(tmp);
1071 return 0;
1072 }
1073
1074
1075 static int __inode_info(u64 inum, u64 ioff, u8 key_type,
1076 struct btrfs_root *fs_root, struct btrfs_path *path,
1077 struct btrfs_key *found_key)
1078 {
1079 int ret;
1080 struct btrfs_key key;
1081 struct extent_buffer *eb;
1082
1083 key.type = key_type;
1084 key.objectid = inum;
1085 key.offset = ioff;
1086
1087 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1088 if (ret < 0)
1089 return ret;
1090
1091 eb = path->nodes[0];
1092 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1093 ret = btrfs_next_leaf(fs_root, path);
1094 if (ret)
1095 return ret;
1096 eb = path->nodes[0];
1097 }
1098
1099 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1100 if (found_key->type != key.type || found_key->objectid != key.objectid)
1101 return 1;
1102
1103 return 0;
1104 }
1105
1106 /*
1107 * this makes the path point to (inum INODE_ITEM ioff)
1108 */
1109 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1110 struct btrfs_path *path)
1111 {
1112 struct btrfs_key key;
1113 return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
1114 &key);
1115 }
1116
1117 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1118 struct btrfs_path *path,
1119 struct btrfs_key *found_key)
1120 {
1121 return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
1122 found_key);
1123 }
1124
1125 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1126 u64 start_off, struct btrfs_path *path,
1127 struct btrfs_inode_extref **ret_extref,
1128 u64 *found_off)
1129 {
1130 int ret, slot;
1131 struct btrfs_key key;
1132 struct btrfs_key found_key;
1133 struct btrfs_inode_extref *extref;
1134 struct extent_buffer *leaf;
1135 unsigned long ptr;
1136
1137 key.objectid = inode_objectid;
1138 btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1139 key.offset = start_off;
1140
1141 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1142 if (ret < 0)
1143 return ret;
1144
1145 while (1) {
1146 leaf = path->nodes[0];
1147 slot = path->slots[0];
1148 if (slot >= btrfs_header_nritems(leaf)) {
1149 /*
1150 * If the item at offset is not found,
1151 * btrfs_search_slot will point us to the slot
1152 * where it should be inserted. In our case
1153 * that will be the slot directly before the
1154 * next INODE_REF_KEY_V2 item. In the case
1155 * that we're pointing to the last slot in a
1156 * leaf, we must move one leaf over.
1157 */
1158 ret = btrfs_next_leaf(root, path);
1159 if (ret) {
1160 if (ret >= 1)
1161 ret = -ENOENT;
1162 break;
1163 }
1164 continue;
1165 }
1166
1167 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1168
1169 /*
1170 * Check that we're still looking at an extended ref key for
1171 * this particular objectid. If we have different
1172 * objectid or type then there are no more to be found
1173 * in the tree and we can exit.
1174 */
1175 ret = -ENOENT;
1176 if (found_key.objectid != inode_objectid)
1177 break;
1178 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1179 break;
1180
1181 ret = 0;
1182 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1183 extref = (struct btrfs_inode_extref *)ptr;
1184 *ret_extref = extref;
1185 if (found_off)
1186 *found_off = found_key.offset;
1187 break;
1188 }
1189
1190 return ret;
1191 }
1192
1193 /*
1194 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1195 * Elements of the path are separated by '/' and the path is guaranteed to be
1196 * 0-terminated. the path is only given within the current file system.
1197 * Therefore, it never starts with a '/'. the caller is responsible to provide
1198 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1199 * the start point of the resulting string is returned. this pointer is within
1200 * dest, normally.
1201 * in case the path buffer would overflow, the pointer is decremented further
1202 * as if output was written to the buffer, though no more output is actually
1203 * generated. that way, the caller can determine how much space would be
1204 * required for the path to fit into the buffer. in that case, the returned
1205 * value will be smaller than dest. callers must check this!
1206 */
1207 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1208 u32 name_len, unsigned long name_off,
1209 struct extent_buffer *eb_in, u64 parent,
1210 char *dest, u32 size)
1211 {
1212 int slot;
1213 u64 next_inum;
1214 int ret;
1215 s64 bytes_left = ((s64)size) - 1;
1216 struct extent_buffer *eb = eb_in;
1217 struct btrfs_key found_key;
1218 int leave_spinning = path->leave_spinning;
1219 struct btrfs_inode_ref *iref;
1220
1221 if (bytes_left >= 0)
1222 dest[bytes_left] = '\0';
1223
1224 path->leave_spinning = 1;
1225 while (1) {
1226 bytes_left -= name_len;
1227 if (bytes_left >= 0)
1228 read_extent_buffer(eb, dest + bytes_left,
1229 name_off, name_len);
1230 if (eb != eb_in) {
1231 btrfs_tree_read_unlock_blocking(eb);
1232 free_extent_buffer(eb);
1233 }
1234 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1235 if (ret > 0)
1236 ret = -ENOENT;
1237 if (ret)
1238 break;
1239
1240 next_inum = found_key.offset;
1241
1242 /* regular exit ahead */
1243 if (parent == next_inum)
1244 break;
1245
1246 slot = path->slots[0];
1247 eb = path->nodes[0];
1248 /* make sure we can use eb after releasing the path */
1249 if (eb != eb_in) {
1250 atomic_inc(&eb->refs);
1251 btrfs_tree_read_lock(eb);
1252 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1253 }
1254 btrfs_release_path(path);
1255 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1256
1257 name_len = btrfs_inode_ref_name_len(eb, iref);
1258 name_off = (unsigned long)(iref + 1);
1259
1260 parent = next_inum;
1261 --bytes_left;
1262 if (bytes_left >= 0)
1263 dest[bytes_left] = '/';
1264 }
1265
1266 btrfs_release_path(path);
1267 path->leave_spinning = leave_spinning;
1268
1269 if (ret)
1270 return ERR_PTR(ret);
1271
1272 return dest + bytes_left;
1273 }
1274
1275 /*
1276 * this makes the path point to (logical EXTENT_ITEM *)
1277 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1278 * tree blocks and <0 on error.
1279 */
1280 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1281 struct btrfs_path *path, struct btrfs_key *found_key,
1282 u64 *flags_ret)
1283 {
1284 int ret;
1285 u64 flags;
1286 u32 item_size;
1287 struct extent_buffer *eb;
1288 struct btrfs_extent_item *ei;
1289 struct btrfs_key key;
1290
1291 key.type = BTRFS_EXTENT_ITEM_KEY;
1292 key.objectid = logical;
1293 key.offset = (u64)-1;
1294
1295 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1296 if (ret < 0)
1297 return ret;
1298 ret = btrfs_previous_item(fs_info->extent_root, path,
1299 0, BTRFS_EXTENT_ITEM_KEY);
1300 if (ret < 0)
1301 return ret;
1302
1303 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1304 if (found_key->type != BTRFS_EXTENT_ITEM_KEY ||
1305 found_key->objectid > logical ||
1306 found_key->objectid + found_key->offset <= logical) {
1307 pr_debug("logical %llu is not within any extent\n",
1308 (unsigned long long)logical);
1309 return -ENOENT;
1310 }
1311
1312 eb = path->nodes[0];
1313 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1314 BUG_ON(item_size < sizeof(*ei));
1315
1316 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1317 flags = btrfs_extent_flags(eb, ei);
1318
1319 pr_debug("logical %llu is at position %llu within the extent (%llu "
1320 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1321 (unsigned long long)logical,
1322 (unsigned long long)(logical - found_key->objectid),
1323 (unsigned long long)found_key->objectid,
1324 (unsigned long long)found_key->offset,
1325 (unsigned long long)flags, item_size);
1326
1327 WARN_ON(!flags_ret);
1328 if (flags_ret) {
1329 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1330 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1331 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1332 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1333 else
1334 BUG_ON(1);
1335 return 0;
1336 }
1337
1338 return -EIO;
1339 }
1340
1341 /*
1342 * helper function to iterate extent inline refs. ptr must point to a 0 value
1343 * for the first call and may be modified. it is used to track state.
1344 * if more refs exist, 0 is returned and the next call to
1345 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1346 * next ref. after the last ref was processed, 1 is returned.
1347 * returns <0 on error
1348 */
1349 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1350 struct btrfs_extent_item *ei, u32 item_size,
1351 struct btrfs_extent_inline_ref **out_eiref,
1352 int *out_type)
1353 {
1354 unsigned long end;
1355 u64 flags;
1356 struct btrfs_tree_block_info *info;
1357
1358 if (!*ptr) {
1359 /* first call */
1360 flags = btrfs_extent_flags(eb, ei);
1361 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1362 info = (struct btrfs_tree_block_info *)(ei + 1);
1363 *out_eiref =
1364 (struct btrfs_extent_inline_ref *)(info + 1);
1365 } else {
1366 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1367 }
1368 *ptr = (unsigned long)*out_eiref;
1369 if ((void *)*ptr >= (void *)ei + item_size)
1370 return -ENOENT;
1371 }
1372
1373 end = (unsigned long)ei + item_size;
1374 *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1375 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1376
1377 *ptr += btrfs_extent_inline_ref_size(*out_type);
1378 WARN_ON(*ptr > end);
1379 if (*ptr == end)
1380 return 1; /* last */
1381
1382 return 0;
1383 }
1384
1385 /*
1386 * reads the tree block backref for an extent. tree level and root are returned
1387 * through out_level and out_root. ptr must point to a 0 value for the first
1388 * call and may be modified (see __get_extent_inline_ref comment).
1389 * returns 0 if data was provided, 1 if there was no more data to provide or
1390 * <0 on error.
1391 */
1392 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1393 struct btrfs_extent_item *ei, u32 item_size,
1394 u64 *out_root, u8 *out_level)
1395 {
1396 int ret;
1397 int type;
1398 struct btrfs_tree_block_info *info;
1399 struct btrfs_extent_inline_ref *eiref;
1400
1401 if (*ptr == (unsigned long)-1)
1402 return 1;
1403
1404 while (1) {
1405 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1406 &eiref, &type);
1407 if (ret < 0)
1408 return ret;
1409
1410 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1411 type == BTRFS_SHARED_BLOCK_REF_KEY)
1412 break;
1413
1414 if (ret == 1)
1415 return 1;
1416 }
1417
1418 /* we can treat both ref types equally here */
1419 info = (struct btrfs_tree_block_info *)(ei + 1);
1420 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1421 *out_level = btrfs_tree_block_level(eb, info);
1422
1423 if (ret == 1)
1424 *ptr = (unsigned long)-1;
1425
1426 return 0;
1427 }
1428
1429 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1430 u64 root, u64 extent_item_objectid,
1431 iterate_extent_inodes_t *iterate, void *ctx)
1432 {
1433 struct extent_inode_elem *eie;
1434 int ret = 0;
1435
1436 for (eie = inode_list; eie; eie = eie->next) {
1437 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1438 "root %llu\n", extent_item_objectid,
1439 eie->inum, eie->offset, root);
1440 ret = iterate(eie->inum, eie->offset, root, ctx);
1441 if (ret) {
1442 pr_debug("stopping iteration for %llu due to ret=%d\n",
1443 extent_item_objectid, ret);
1444 break;
1445 }
1446 }
1447
1448 return ret;
1449 }
1450
1451 /*
1452 * calls iterate() for every inode that references the extent identified by
1453 * the given parameters.
1454 * when the iterator function returns a non-zero value, iteration stops.
1455 */
1456 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1457 u64 extent_item_objectid, u64 extent_item_pos,
1458 int search_commit_root,
1459 iterate_extent_inodes_t *iterate, void *ctx)
1460 {
1461 int ret;
1462 struct btrfs_trans_handle *trans;
1463 struct ulist *refs = NULL;
1464 struct ulist *roots = NULL;
1465 struct ulist_node *ref_node = NULL;
1466 struct ulist_node *root_node = NULL;
1467 struct seq_list tree_mod_seq_elem = {};
1468 struct ulist_iterator ref_uiter;
1469 struct ulist_iterator root_uiter;
1470
1471 pr_debug("resolving all inodes for extent %llu\n",
1472 extent_item_objectid);
1473
1474 if (search_commit_root) {
1475 trans = BTRFS_BACKREF_SEARCH_COMMIT_ROOT;
1476 } else {
1477 trans = btrfs_join_transaction(fs_info->extent_root);
1478 if (IS_ERR(trans))
1479 return PTR_ERR(trans);
1480 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1481 }
1482
1483 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1484 tree_mod_seq_elem.seq, &refs,
1485 &extent_item_pos);
1486 if (ret)
1487 goto out;
1488
1489 ULIST_ITER_INIT(&ref_uiter);
1490 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1491 ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
1492 tree_mod_seq_elem.seq, &roots);
1493 if (ret)
1494 break;
1495 ULIST_ITER_INIT(&root_uiter);
1496 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1497 pr_debug("root %llu references leaf %llu, data list "
1498 "%#llx\n", root_node->val, ref_node->val,
1499 (long long)ref_node->aux);
1500 ret = iterate_leaf_refs((struct extent_inode_elem *)
1501 (uintptr_t)ref_node->aux,
1502 root_node->val,
1503 extent_item_objectid,
1504 iterate, ctx);
1505 }
1506 ulist_free(roots);
1507 }
1508
1509 free_leaf_list(refs);
1510 out:
1511 if (!search_commit_root) {
1512 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1513 btrfs_end_transaction(trans, fs_info->extent_root);
1514 }
1515
1516 return ret;
1517 }
1518
1519 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1520 struct btrfs_path *path,
1521 iterate_extent_inodes_t *iterate, void *ctx)
1522 {
1523 int ret;
1524 u64 extent_item_pos;
1525 u64 flags = 0;
1526 struct btrfs_key found_key;
1527 int search_commit_root = path->search_commit_root;
1528
1529 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1530 btrfs_release_path(path);
1531 if (ret < 0)
1532 return ret;
1533 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1534 return -EINVAL;
1535
1536 extent_item_pos = logical - found_key.objectid;
1537 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1538 extent_item_pos, search_commit_root,
1539 iterate, ctx);
1540
1541 return ret;
1542 }
1543
1544 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1545 struct extent_buffer *eb, void *ctx);
1546
1547 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1548 struct btrfs_path *path,
1549 iterate_irefs_t *iterate, void *ctx)
1550 {
1551 int ret = 0;
1552 int slot;
1553 u32 cur;
1554 u32 len;
1555 u32 name_len;
1556 u64 parent = 0;
1557 int found = 0;
1558 struct extent_buffer *eb;
1559 struct btrfs_item *item;
1560 struct btrfs_inode_ref *iref;
1561 struct btrfs_key found_key;
1562
1563 while (!ret) {
1564 path->leave_spinning = 1;
1565 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1566 &found_key);
1567 if (ret < 0)
1568 break;
1569 if (ret) {
1570 ret = found ? 0 : -ENOENT;
1571 break;
1572 }
1573 ++found;
1574
1575 parent = found_key.offset;
1576 slot = path->slots[0];
1577 eb = path->nodes[0];
1578 /* make sure we can use eb after releasing the path */
1579 atomic_inc(&eb->refs);
1580 btrfs_tree_read_lock(eb);
1581 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1582 btrfs_release_path(path);
1583
1584 item = btrfs_item_nr(eb, slot);
1585 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1586
1587 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1588 name_len = btrfs_inode_ref_name_len(eb, iref);
1589 /* path must be released before calling iterate()! */
1590 pr_debug("following ref at offset %u for inode %llu in "
1591 "tree %llu\n", cur,
1592 (unsigned long long)found_key.objectid,
1593 (unsigned long long)fs_root->objectid);
1594 ret = iterate(parent, name_len,
1595 (unsigned long)(iref + 1), eb, ctx);
1596 if (ret)
1597 break;
1598 len = sizeof(*iref) + name_len;
1599 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1600 }
1601 btrfs_tree_read_unlock_blocking(eb);
1602 free_extent_buffer(eb);
1603 }
1604
1605 btrfs_release_path(path);
1606
1607 return ret;
1608 }
1609
1610 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1611 struct btrfs_path *path,
1612 iterate_irefs_t *iterate, void *ctx)
1613 {
1614 int ret;
1615 int slot;
1616 u64 offset = 0;
1617 u64 parent;
1618 int found = 0;
1619 struct extent_buffer *eb;
1620 struct btrfs_inode_extref *extref;
1621 struct extent_buffer *leaf;
1622 u32 item_size;
1623 u32 cur_offset;
1624 unsigned long ptr;
1625
1626 while (1) {
1627 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1628 &offset);
1629 if (ret < 0)
1630 break;
1631 if (ret) {
1632 ret = found ? 0 : -ENOENT;
1633 break;
1634 }
1635 ++found;
1636
1637 slot = path->slots[0];
1638 eb = path->nodes[0];
1639 /* make sure we can use eb after releasing the path */
1640 atomic_inc(&eb->refs);
1641
1642 btrfs_tree_read_lock(eb);
1643 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1644 btrfs_release_path(path);
1645
1646 leaf = path->nodes[0];
1647 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1648 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1649 cur_offset = 0;
1650
1651 while (cur_offset < item_size) {
1652 u32 name_len;
1653
1654 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1655 parent = btrfs_inode_extref_parent(eb, extref);
1656 name_len = btrfs_inode_extref_name_len(eb, extref);
1657 ret = iterate(parent, name_len,
1658 (unsigned long)&extref->name, eb, ctx);
1659 if (ret)
1660 break;
1661
1662 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1663 cur_offset += sizeof(*extref);
1664 }
1665 btrfs_tree_read_unlock_blocking(eb);
1666 free_extent_buffer(eb);
1667
1668 offset++;
1669 }
1670
1671 btrfs_release_path(path);
1672
1673 return ret;
1674 }
1675
1676 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1677 struct btrfs_path *path, iterate_irefs_t *iterate,
1678 void *ctx)
1679 {
1680 int ret;
1681 int found_refs = 0;
1682
1683 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1684 if (!ret)
1685 ++found_refs;
1686 else if (ret != -ENOENT)
1687 return ret;
1688
1689 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1690 if (ret == -ENOENT && found_refs)
1691 return 0;
1692
1693 return ret;
1694 }
1695
1696 /*
1697 * returns 0 if the path could be dumped (probably truncated)
1698 * returns <0 in case of an error
1699 */
1700 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1701 struct extent_buffer *eb, void *ctx)
1702 {
1703 struct inode_fs_paths *ipath = ctx;
1704 char *fspath;
1705 char *fspath_min;
1706 int i = ipath->fspath->elem_cnt;
1707 const int s_ptr = sizeof(char *);
1708 u32 bytes_left;
1709
1710 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1711 ipath->fspath->bytes_left - s_ptr : 0;
1712
1713 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1714 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1715 name_off, eb, inum, fspath_min, bytes_left);
1716 if (IS_ERR(fspath))
1717 return PTR_ERR(fspath);
1718
1719 if (fspath > fspath_min) {
1720 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1721 ++ipath->fspath->elem_cnt;
1722 ipath->fspath->bytes_left = fspath - fspath_min;
1723 } else {
1724 ++ipath->fspath->elem_missed;
1725 ipath->fspath->bytes_missing += fspath_min - fspath;
1726 ipath->fspath->bytes_left = 0;
1727 }
1728
1729 return 0;
1730 }
1731
1732 /*
1733 * this dumps all file system paths to the inode into the ipath struct, provided
1734 * is has been created large enough. each path is zero-terminated and accessed
1735 * from ipath->fspath->val[i].
1736 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1737 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1738 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1739 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1740 * have been needed to return all paths.
1741 */
1742 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1743 {
1744 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1745 inode_to_path, ipath);
1746 }
1747
1748 struct btrfs_data_container *init_data_container(u32 total_bytes)
1749 {
1750 struct btrfs_data_container *data;
1751 size_t alloc_bytes;
1752
1753 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1754 data = vmalloc(alloc_bytes);
1755 if (!data)
1756 return ERR_PTR(-ENOMEM);
1757
1758 if (total_bytes >= sizeof(*data)) {
1759 data->bytes_left = total_bytes - sizeof(*data);
1760 data->bytes_missing = 0;
1761 } else {
1762 data->bytes_missing = sizeof(*data) - total_bytes;
1763 data->bytes_left = 0;
1764 }
1765
1766 data->elem_cnt = 0;
1767 data->elem_missed = 0;
1768
1769 return data;
1770 }
1771
1772 /*
1773 * allocates space to return multiple file system paths for an inode.
1774 * total_bytes to allocate are passed, note that space usable for actual path
1775 * information will be total_bytes - sizeof(struct inode_fs_paths).
1776 * the returned pointer must be freed with free_ipath() in the end.
1777 */
1778 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1779 struct btrfs_path *path)
1780 {
1781 struct inode_fs_paths *ifp;
1782 struct btrfs_data_container *fspath;
1783
1784 fspath = init_data_container(total_bytes);
1785 if (IS_ERR(fspath))
1786 return (void *)fspath;
1787
1788 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1789 if (!ifp) {
1790 kfree(fspath);
1791 return ERR_PTR(-ENOMEM);
1792 }
1793
1794 ifp->btrfs_path = path;
1795 ifp->fspath = fspath;
1796 ifp->fs_root = fs_root;
1797
1798 return ifp;
1799 }
1800
1801 void free_ipath(struct inode_fs_paths *ipath)
1802 {
1803 if (!ipath)
1804 return;
1805 vfree(ipath->fspath);
1806 kfree(ipath);
1807 }
kernel source for telekom puls (alcatel/mediatek)