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FRV: Fix incorrect symbol in copy_thread()
[linux-2.6/libata-dev.git] / fs / btrfs / backref.c
blobf3187938e081c7dcbf842d424f5de6ed06d3f93f
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 rcu_read_lock();
287 root_level = btrfs_header_level(root->node);
288 rcu_read_unlock();
289
290 if (root_level + 1 == level)
291 goto out;
292
293 path->lowest_level = level;
294 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
295 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
296 "%d for key (%llu %u %llu)\n",
297 (unsigned long long)ref->root_id, level, ref->count, ret,
298 (unsigned long long)ref->key_for_search.objectid,
299 ref->key_for_search.type,
300 (unsigned long long)ref->key_for_search.offset);
301 if (ret < 0)
302 goto out;
303
304 eb = path->nodes[level];
305 while (!eb) {
306 if (!level) {
307 WARN_ON(1);
308 ret = 1;
309 goto out;
310 }
311 level--;
312 eb = path->nodes[level];
313 }
314
315 ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
316 time_seq, ref->wanted_disk_byte,
317 extent_item_pos);
318 out:
319 btrfs_free_path(path);
320 return ret;
321 }
322
323 /*
324 * resolve all indirect backrefs from the list
325 */
326 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
327 int search_commit_root, u64 time_seq,
328 struct list_head *head,
329 const u64 *extent_item_pos)
330 {
331 int err;
332 int ret = 0;
333 struct __prelim_ref *ref;
334 struct __prelim_ref *ref_safe;
335 struct __prelim_ref *new_ref;
336 struct ulist *parents;
337 struct ulist_node *node;
338 struct ulist_iterator uiter;
339
340 parents = ulist_alloc(GFP_NOFS);
341 if (!parents)
342 return -ENOMEM;
343
344 /*
345 * _safe allows us to insert directly after the current item without
346 * iterating over the newly inserted items.
347 * we're also allowed to re-assign ref during iteration.
348 */
349 list_for_each_entry_safe(ref, ref_safe, head, list) {
350 if (ref->parent) /* already direct */
351 continue;
352 if (ref->count == 0)
353 continue;
354 err = __resolve_indirect_ref(fs_info, search_commit_root,
355 time_seq, ref, parents,
356 extent_item_pos);
357 if (err) {
358 if (ret == 0)
359 ret = err;
360 continue;
361 }
362
363 /* we put the first parent into the ref at hand */
364 ULIST_ITER_INIT(&uiter);
365 node = ulist_next(parents, &uiter);
366 ref->parent = node ? node->val : 0;
367 ref->inode_list = node ?
368 (struct extent_inode_elem *)(uintptr_t)node->aux : 0;
369
370 /* additional parents require new refs being added here */
371 while ((node = ulist_next(parents, &uiter))) {
372 new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
373 if (!new_ref) {
374 ret = -ENOMEM;
375 break;
376 }
377 memcpy(new_ref, ref, sizeof(*ref));
378 new_ref->parent = node->val;
379 new_ref->inode_list = (struct extent_inode_elem *)
380 (uintptr_t)node->aux;
381 list_add(&new_ref->list, &ref->list);
382 }
383 ulist_reinit(parents);
384 }
385
386 ulist_free(parents);
387 return ret;
388 }
389
390 static inline int ref_for_same_block(struct __prelim_ref *ref1,
391 struct __prelim_ref *ref2)
392 {
393 if (ref1->level != ref2->level)
394 return 0;
395 if (ref1->root_id != ref2->root_id)
396 return 0;
397 if (ref1->key_for_search.type != ref2->key_for_search.type)
398 return 0;
399 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
400 return 0;
401 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
402 return 0;
403 if (ref1->parent != ref2->parent)
404 return 0;
405
406 return 1;
407 }
408
409 /*
410 * read tree blocks and add keys where required.
411 */
412 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
413 struct list_head *head)
414 {
415 struct list_head *pos;
416 struct extent_buffer *eb;
417
418 list_for_each(pos, head) {
419 struct __prelim_ref *ref;
420 ref = list_entry(pos, struct __prelim_ref, list);
421
422 if (ref->parent)
423 continue;
424 if (ref->key_for_search.type)
425 continue;
426 BUG_ON(!ref->wanted_disk_byte);
427 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
428 fs_info->tree_root->leafsize, 0);
429 BUG_ON(!eb);
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 int __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
467 ref2 = list_entry(pos2, struct __prelim_ref, list);
468
469 if (mode == 1) {
470 if (!ref_for_same_block(ref1, ref2))
471 continue;
472 if (!ref1->parent && ref2->parent) {
473 xchg = ref1;
474 ref1 = ref2;
475 ref2 = xchg;
476 }
477 ref1->count += ref2->count;
478 } else {
479 if (ref1->parent != ref2->parent)
480 continue;
481 ref1->count += ref2->count;
482 }
483 list_del(&ref2->list);
484 kfree(ref2);
485 }
486
487 }
488 return 0;
489 }
490
491 /*
492 * add all currently queued delayed refs from this head whose seq nr is
493 * smaller or equal that seq to the list
494 */
495 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
496 struct list_head *prefs)
497 {
498 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
499 struct rb_node *n = &head->node.rb_node;
500 struct btrfs_key key;
501 struct btrfs_key op_key = {0};
502 int sgn;
503 int ret = 0;
504
505 if (extent_op && extent_op->update_key)
506 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
507
508 while ((n = rb_prev(n))) {
509 struct btrfs_delayed_ref_node *node;
510 node = rb_entry(n, struct btrfs_delayed_ref_node,
511 rb_node);
512 if (node->bytenr != head->node.bytenr)
513 break;
514 WARN_ON(node->is_head);
515
516 if (node->seq > seq)
517 continue;
518
519 switch (node->action) {
520 case BTRFS_ADD_DELAYED_EXTENT:
521 case BTRFS_UPDATE_DELAYED_HEAD:
522 WARN_ON(1);
523 continue;
524 case BTRFS_ADD_DELAYED_REF:
525 sgn = 1;
526 break;
527 case BTRFS_DROP_DELAYED_REF:
528 sgn = -1;
529 break;
530 default:
531 BUG_ON(1);
532 }
533 switch (node->type) {
534 case BTRFS_TREE_BLOCK_REF_KEY: {
535 struct btrfs_delayed_tree_ref *ref;
536
537 ref = btrfs_delayed_node_to_tree_ref(node);
538 ret = __add_prelim_ref(prefs, ref->root, &op_key,
539 ref->level + 1, 0, node->bytenr,
540 node->ref_mod * sgn);
541 break;
542 }
543 case BTRFS_SHARED_BLOCK_REF_KEY: {
544 struct btrfs_delayed_tree_ref *ref;
545
546 ref = btrfs_delayed_node_to_tree_ref(node);
547 ret = __add_prelim_ref(prefs, ref->root, NULL,
548 ref->level + 1, ref->parent,
549 node->bytenr,
550 node->ref_mod * sgn);
551 break;
552 }
553 case BTRFS_EXTENT_DATA_REF_KEY: {
554 struct btrfs_delayed_data_ref *ref;
555 ref = btrfs_delayed_node_to_data_ref(node);
556
557 key.objectid = ref->objectid;
558 key.type = BTRFS_EXTENT_DATA_KEY;
559 key.offset = ref->offset;
560 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
561 node->bytenr,
562 node->ref_mod * sgn);
563 break;
564 }
565 case BTRFS_SHARED_DATA_REF_KEY: {
566 struct btrfs_delayed_data_ref *ref;
567
568 ref = btrfs_delayed_node_to_data_ref(node);
569
570 key.objectid = ref->objectid;
571 key.type = BTRFS_EXTENT_DATA_KEY;
572 key.offset = ref->offset;
573 ret = __add_prelim_ref(prefs, ref->root, &key, 0,
574 ref->parent, node->bytenr,
575 node->ref_mod * sgn);
576 break;
577 }
578 default:
579 WARN_ON(1);
580 }
581 BUG_ON(ret);
582 }
583
584 return 0;
585 }
586
587 /*
588 * add all inline backrefs for bytenr to the list
589 */
590 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
591 struct btrfs_path *path, u64 bytenr,
592 int *info_level, struct list_head *prefs)
593 {
594 int ret = 0;
595 int slot;
596 struct extent_buffer *leaf;
597 struct btrfs_key key;
598 unsigned long ptr;
599 unsigned long end;
600 struct btrfs_extent_item *ei;
601 u64 flags;
602 u64 item_size;
603
604 /*
605 * enumerate all inline refs
606 */
607 leaf = path->nodes[0];
608 slot = path->slots[0];
609
610 item_size = btrfs_item_size_nr(leaf, slot);
611 BUG_ON(item_size < sizeof(*ei));
612
613 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
614 flags = btrfs_extent_flags(leaf, ei);
615
616 ptr = (unsigned long)(ei + 1);
617 end = (unsigned long)ei + item_size;
618
619 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
620 struct btrfs_tree_block_info *info;
621
622 info = (struct btrfs_tree_block_info *)ptr;
623 *info_level = btrfs_tree_block_level(leaf, info);
624 ptr += sizeof(struct btrfs_tree_block_info);
625 BUG_ON(ptr > end);
626 } else {
627 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
628 }
629
630 while (ptr < end) {
631 struct btrfs_extent_inline_ref *iref;
632 u64 offset;
633 int type;
634
635 iref = (struct btrfs_extent_inline_ref *)ptr;
636 type = btrfs_extent_inline_ref_type(leaf, iref);
637 offset = btrfs_extent_inline_ref_offset(leaf, iref);
638
639 switch (type) {
640 case BTRFS_SHARED_BLOCK_REF_KEY:
641 ret = __add_prelim_ref(prefs, 0, NULL,
642 *info_level + 1, offset,
643 bytenr, 1);
644 break;
645 case BTRFS_SHARED_DATA_REF_KEY: {
646 struct btrfs_shared_data_ref *sdref;
647 int count;
648
649 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
650 count = btrfs_shared_data_ref_count(leaf, sdref);
651 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
652 bytenr, count);
653 break;
654 }
655 case BTRFS_TREE_BLOCK_REF_KEY:
656 ret = __add_prelim_ref(prefs, offset, NULL,
657 *info_level + 1, 0,
658 bytenr, 1);
659 break;
660 case BTRFS_EXTENT_DATA_REF_KEY: {
661 struct btrfs_extent_data_ref *dref;
662 int count;
663 u64 root;
664
665 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
666 count = btrfs_extent_data_ref_count(leaf, dref);
667 key.objectid = btrfs_extent_data_ref_objectid(leaf,
668 dref);
669 key.type = BTRFS_EXTENT_DATA_KEY;
670 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
671 root = btrfs_extent_data_ref_root(leaf, dref);
672 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
673 bytenr, count);
674 break;
675 }
676 default:
677 WARN_ON(1);
678 }
679 BUG_ON(ret);
680 ptr += btrfs_extent_inline_ref_size(type);
681 }
682
683 return 0;
684 }
685
686 /*
687 * add all non-inline backrefs for bytenr to the list
688 */
689 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
690 struct btrfs_path *path, u64 bytenr,
691 int info_level, struct list_head *prefs)
692 {
693 struct btrfs_root *extent_root = fs_info->extent_root;
694 int ret;
695 int slot;
696 struct extent_buffer *leaf;
697 struct btrfs_key key;
698
699 while (1) {
700 ret = btrfs_next_item(extent_root, path);
701 if (ret < 0)
702 break;
703 if (ret) {
704 ret = 0;
705 break;
706 }
707
708 slot = path->slots[0];
709 leaf = path->nodes[0];
710 btrfs_item_key_to_cpu(leaf, &key, slot);
711
712 if (key.objectid != bytenr)
713 break;
714 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
715 continue;
716 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
717 break;
718
719 switch (key.type) {
720 case BTRFS_SHARED_BLOCK_REF_KEY:
721 ret = __add_prelim_ref(prefs, 0, NULL,
722 info_level + 1, key.offset,
723 bytenr, 1);
724 break;
725 case BTRFS_SHARED_DATA_REF_KEY: {
726 struct btrfs_shared_data_ref *sdref;
727 int count;
728
729 sdref = btrfs_item_ptr(leaf, slot,
730 struct btrfs_shared_data_ref);
731 count = btrfs_shared_data_ref_count(leaf, sdref);
732 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
733 bytenr, count);
734 break;
735 }
736 case BTRFS_TREE_BLOCK_REF_KEY:
737 ret = __add_prelim_ref(prefs, key.offset, NULL,
738 info_level + 1, 0,
739 bytenr, 1);
740 break;
741 case BTRFS_EXTENT_DATA_REF_KEY: {
742 struct btrfs_extent_data_ref *dref;
743 int count;
744 u64 root;
745
746 dref = btrfs_item_ptr(leaf, slot,
747 struct btrfs_extent_data_ref);
748 count = btrfs_extent_data_ref_count(leaf, dref);
749 key.objectid = btrfs_extent_data_ref_objectid(leaf,
750 dref);
751 key.type = BTRFS_EXTENT_DATA_KEY;
752 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
753 root = btrfs_extent_data_ref_root(leaf, dref);
754 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
755 bytenr, count);
756 break;
757 }
758 default:
759 WARN_ON(1);
760 }
761 BUG_ON(ret);
762 }
763
764 return ret;
765 }
766
767 /*
768 * this adds all existing backrefs (inline backrefs, backrefs and delayed
769 * refs) for the given bytenr to the refs list, merges duplicates and resolves
770 * indirect refs to their parent bytenr.
771 * When roots are found, they're added to the roots list
772 *
773 * FIXME some caching might speed things up
774 */
775 static int find_parent_nodes(struct btrfs_trans_handle *trans,
776 struct btrfs_fs_info *fs_info, u64 bytenr,
777 u64 time_seq, struct ulist *refs,
778 struct ulist *roots, const u64 *extent_item_pos)
779 {
780 struct btrfs_key key;
781 struct btrfs_path *path;
782 struct btrfs_delayed_ref_root *delayed_refs = NULL;
783 struct btrfs_delayed_ref_head *head;
784 int info_level = 0;
785 int ret;
786 int search_commit_root = (trans == BTRFS_BACKREF_SEARCH_COMMIT_ROOT);
787 struct list_head prefs_delayed;
788 struct list_head prefs;
789 struct __prelim_ref *ref;
790
791 INIT_LIST_HEAD(&prefs);
792 INIT_LIST_HEAD(&prefs_delayed);
793
794 key.objectid = bytenr;
795 key.type = BTRFS_EXTENT_ITEM_KEY;
796 key.offset = (u64)-1;
797
798 path = btrfs_alloc_path();
799 if (!path)
800 return -ENOMEM;
801 path->search_commit_root = !!search_commit_root;
802
803 /*
804 * grab both a lock on the path and a lock on the delayed ref head.
805 * We need both to get a consistent picture of how the refs look
806 * at a specified point in time
807 */
808 again:
809 head = NULL;
810
811 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
812 if (ret < 0)
813 goto out;
814 BUG_ON(ret == 0);
815
816 if (trans != BTRFS_BACKREF_SEARCH_COMMIT_ROOT) {
817 /*
818 * look if there are updates for this ref queued and lock the
819 * head
820 */
821 delayed_refs = &trans->transaction->delayed_refs;
822 spin_lock(&delayed_refs->lock);
823 head = btrfs_find_delayed_ref_head(trans, bytenr);
824 if (head) {
825 if (!mutex_trylock(&head->mutex)) {
826 atomic_inc(&head->node.refs);
827 spin_unlock(&delayed_refs->lock);
828
829 btrfs_release_path(path);
830
831 /*
832 * Mutex was contended, block until it's
833 * released and try again
834 */
835 mutex_lock(&head->mutex);
836 mutex_unlock(&head->mutex);
837 btrfs_put_delayed_ref(&head->node);
838 goto again;
839 }
840 ret = __add_delayed_refs(head, time_seq,
841 &prefs_delayed);
842 mutex_unlock(&head->mutex);
843 if (ret) {
844 spin_unlock(&delayed_refs->lock);
845 goto out;
846 }
847 }
848 spin_unlock(&delayed_refs->lock);
849 }
850
851 if (path->slots[0]) {
852 struct extent_buffer *leaf;
853 int slot;
854
855 path->slots[0]--;
856 leaf = path->nodes[0];
857 slot = path->slots[0];
858 btrfs_item_key_to_cpu(leaf, &key, slot);
859 if (key.objectid == bytenr &&
860 key.type == BTRFS_EXTENT_ITEM_KEY) {
861 ret = __add_inline_refs(fs_info, path, bytenr,
862 &info_level, &prefs);
863 if (ret)
864 goto out;
865 ret = __add_keyed_refs(fs_info, path, bytenr,
866 info_level, &prefs);
867 if (ret)
868 goto out;
869 }
870 }
871 btrfs_release_path(path);
872
873 list_splice_init(&prefs_delayed, &prefs);
874
875 ret = __add_missing_keys(fs_info, &prefs);
876 if (ret)
877 goto out;
878
879 ret = __merge_refs(&prefs, 1);
880 if (ret)
881 goto out;
882
883 ret = __resolve_indirect_refs(fs_info, search_commit_root, time_seq,
884 &prefs, extent_item_pos);
885 if (ret)
886 goto out;
887
888 ret = __merge_refs(&prefs, 2);
889 if (ret)
890 goto out;
891
892 while (!list_empty(&prefs)) {
893 ref = list_first_entry(&prefs, struct __prelim_ref, list);
894 list_del(&ref->list);
895 if (ref->count < 0)
896 WARN_ON(1);
897 if (ref->count && ref->root_id && ref->parent == 0) {
898 /* no parent == root of tree */
899 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
900 BUG_ON(ret < 0);
901 }
902 if (ref->count && ref->parent) {
903 struct extent_inode_elem *eie = NULL;
904 if (extent_item_pos && !ref->inode_list) {
905 u32 bsz;
906 struct extent_buffer *eb;
907 bsz = btrfs_level_size(fs_info->extent_root,
908 info_level);
909 eb = read_tree_block(fs_info->extent_root,
910 ref->parent, bsz, 0);
911 BUG_ON(!eb);
912 ret = find_extent_in_eb(eb, bytenr,
913 *extent_item_pos, &eie);
914 ref->inode_list = eie;
915 free_extent_buffer(eb);
916 }
917 ret = ulist_add_merge(refs, ref->parent,
918 (uintptr_t)ref->inode_list,
919 (u64 *)&eie, GFP_NOFS);
920 if (!ret && extent_item_pos) {
921 /*
922 * we've recorded that parent, so we must extend
923 * its inode list here
924 */
925 BUG_ON(!eie);
926 while (eie->next)
927 eie = eie->next;
928 eie->next = ref->inode_list;
929 }
930 BUG_ON(ret < 0);
931 }
932 kfree(ref);
933 }
934
935 out:
936 btrfs_free_path(path);
937 while (!list_empty(&prefs)) {
938 ref = list_first_entry(&prefs, struct __prelim_ref, list);
939 list_del(&ref->list);
940 kfree(ref);
941 }
942 while (!list_empty(&prefs_delayed)) {
943 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
944 list);
945 list_del(&ref->list);
946 kfree(ref);
947 }
948
949 return ret;
950 }
951
952 static void free_leaf_list(struct ulist *blocks)
953 {
954 struct ulist_node *node = NULL;
955 struct extent_inode_elem *eie;
956 struct extent_inode_elem *eie_next;
957 struct ulist_iterator uiter;
958
959 ULIST_ITER_INIT(&uiter);
960 while ((node = ulist_next(blocks, &uiter))) {
961 if (!node->aux)
962 continue;
963 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
964 for (; eie; eie = eie_next) {
965 eie_next = eie->next;
966 kfree(eie);
967 }
968 node->aux = 0;
969 }
970
971 ulist_free(blocks);
972 }
973
974 /*
975 * Finds all leafs with a reference to the specified combination of bytenr and
976 * offset. key_list_head will point to a list of corresponding keys (caller must
977 * free each list element). The leafs will be stored in the leafs ulist, which
978 * must be freed with ulist_free.
979 *
980 * returns 0 on success, <0 on error
981 */
982 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
983 struct btrfs_fs_info *fs_info, u64 bytenr,
984 u64 time_seq, struct ulist **leafs,
985 const u64 *extent_item_pos)
986 {
987 struct ulist *tmp;
988 int ret;
989
990 tmp = ulist_alloc(GFP_NOFS);
991 if (!tmp)
992 return -ENOMEM;
993 *leafs = ulist_alloc(GFP_NOFS);
994 if (!*leafs) {
995 ulist_free(tmp);
996 return -ENOMEM;
997 }
998
999 ret = find_parent_nodes(trans, fs_info, bytenr,
1000 time_seq, *leafs, tmp, extent_item_pos);
1001 ulist_free(tmp);
1002
1003 if (ret < 0 && ret != -ENOENT) {
1004 free_leaf_list(*leafs);
1005 return ret;
1006 }
1007
1008 return 0;
1009 }
1010
1011 /*
1012 * walk all backrefs for a given extent to find all roots that reference this
1013 * extent. Walking a backref means finding all extents that reference this
1014 * extent and in turn walk the backrefs of those, too. Naturally this is a
1015 * recursive process, but here it is implemented in an iterative fashion: We
1016 * find all referencing extents for the extent in question and put them on a
1017 * list. In turn, we find all referencing extents for those, further appending
1018 * to the list. The way we iterate the list allows adding more elements after
1019 * the current while iterating. The process stops when we reach the end of the
1020 * list. Found roots are added to the roots list.
1021 *
1022 * returns 0 on success, < 0 on error.
1023 */
1024 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1025 struct btrfs_fs_info *fs_info, u64 bytenr,
1026 u64 time_seq, struct ulist **roots)
1027 {
1028 struct ulist *tmp;
1029 struct ulist_node *node = NULL;
1030 struct ulist_iterator uiter;
1031 int ret;
1032
1033 tmp = ulist_alloc(GFP_NOFS);
1034 if (!tmp)
1035 return -ENOMEM;
1036 *roots = ulist_alloc(GFP_NOFS);
1037 if (!*roots) {
1038 ulist_free(tmp);
1039 return -ENOMEM;
1040 }
1041
1042 ULIST_ITER_INIT(&uiter);
1043 while (1) {
1044 ret = find_parent_nodes(trans, fs_info, bytenr,
1045 time_seq, tmp, *roots, NULL);
1046 if (ret < 0 && ret != -ENOENT) {
1047 ulist_free(tmp);
1048 ulist_free(*roots);
1049 return ret;
1050 }
1051 node = ulist_next(tmp, &uiter);
1052 if (!node)
1053 break;
1054 bytenr = node->val;
1055 }
1056
1057 ulist_free(tmp);
1058 return 0;
1059 }
1060
1061
1062 static int __inode_info(u64 inum, u64 ioff, u8 key_type,
1063 struct btrfs_root *fs_root, struct btrfs_path *path,
1064 struct btrfs_key *found_key)
1065 {
1066 int ret;
1067 struct btrfs_key key;
1068 struct extent_buffer *eb;
1069
1070 key.type = key_type;
1071 key.objectid = inum;
1072 key.offset = ioff;
1073
1074 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1075 if (ret < 0)
1076 return ret;
1077
1078 eb = path->nodes[0];
1079 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1080 ret = btrfs_next_leaf(fs_root, path);
1081 if (ret)
1082 return ret;
1083 eb = path->nodes[0];
1084 }
1085
1086 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1087 if (found_key->type != key.type || found_key->objectid != key.objectid)
1088 return 1;
1089
1090 return 0;
1091 }
1092
1093 /*
1094 * this makes the path point to (inum INODE_ITEM ioff)
1095 */
1096 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1097 struct btrfs_path *path)
1098 {
1099 struct btrfs_key key;
1100 return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
1101 &key);
1102 }
1103
1104 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1105 struct btrfs_path *path,
1106 struct btrfs_key *found_key)
1107 {
1108 return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
1109 found_key);
1110 }
1111
1112 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1113 u64 start_off, struct btrfs_path *path,
1114 struct btrfs_inode_extref **ret_extref,
1115 u64 *found_off)
1116 {
1117 int ret, slot;
1118 struct btrfs_key key;
1119 struct btrfs_key found_key;
1120 struct btrfs_inode_extref *extref;
1121 struct extent_buffer *leaf;
1122 unsigned long ptr;
1123
1124 key.objectid = inode_objectid;
1125 btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1126 key.offset = start_off;
1127
1128 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1129 if (ret < 0)
1130 return ret;
1131
1132 while (1) {
1133 leaf = path->nodes[0];
1134 slot = path->slots[0];
1135 if (slot >= btrfs_header_nritems(leaf)) {
1136 /*
1137 * If the item at offset is not found,
1138 * btrfs_search_slot will point us to the slot
1139 * where it should be inserted. In our case
1140 * that will be the slot directly before the
1141 * next INODE_REF_KEY_V2 item. In the case
1142 * that we're pointing to the last slot in a
1143 * leaf, we must move one leaf over.
1144 */
1145 ret = btrfs_next_leaf(root, path);
1146 if (ret) {
1147 if (ret >= 1)
1148 ret = -ENOENT;
1149 break;
1150 }
1151 continue;
1152 }
1153
1154 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1155
1156 /*
1157 * Check that we're still looking at an extended ref key for
1158 * this particular objectid. If we have different
1159 * objectid or type then there are no more to be found
1160 * in the tree and we can exit.
1161 */
1162 ret = -ENOENT;
1163 if (found_key.objectid != inode_objectid)
1164 break;
1165 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1166 break;
1167
1168 ret = 0;
1169 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1170 extref = (struct btrfs_inode_extref *)ptr;
1171 *ret_extref = extref;
1172 if (found_off)
1173 *found_off = found_key.offset;
1174 break;
1175 }
1176
1177 return ret;
1178 }
1179
1180 static char *ref_to_path(struct btrfs_root *fs_root,
1181 struct btrfs_path *path,
1182 u32 name_len, unsigned long name_off,
1183 struct extent_buffer *eb_in, u64 parent,
1184 char *dest, u32 size)
1185 {
1186 int slot;
1187 u64 next_inum;
1188 int ret;
1189 s64 bytes_left = size - 1;
1190 struct extent_buffer *eb = eb_in;
1191 struct btrfs_key found_key;
1192 int leave_spinning = path->leave_spinning;
1193 struct btrfs_inode_ref *iref;
1194
1195 if (bytes_left >= 0)
1196 dest[bytes_left] = '\0';
1197
1198 path->leave_spinning = 1;
1199 while (1) {
1200 bytes_left -= name_len;
1201 if (bytes_left >= 0)
1202 read_extent_buffer(eb, dest + bytes_left,
1203 name_off, name_len);
1204 if (eb != eb_in) {
1205 btrfs_tree_read_unlock_blocking(eb);
1206 free_extent_buffer(eb);
1207 }
1208 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1209 if (ret > 0)
1210 ret = -ENOENT;
1211 if (ret)
1212 break;
1213
1214 next_inum = found_key.offset;
1215
1216 /* regular exit ahead */
1217 if (parent == next_inum)
1218 break;
1219
1220 slot = path->slots[0];
1221 eb = path->nodes[0];
1222 /* make sure we can use eb after releasing the path */
1223 if (eb != eb_in) {
1224 atomic_inc(&eb->refs);
1225 btrfs_tree_read_lock(eb);
1226 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1227 }
1228 btrfs_release_path(path);
1229 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1230
1231 name_len = btrfs_inode_ref_name_len(eb, iref);
1232 name_off = (unsigned long)(iref + 1);
1233
1234 parent = next_inum;
1235 --bytes_left;
1236 if (bytes_left >= 0)
1237 dest[bytes_left] = '/';
1238 }
1239
1240 btrfs_release_path(path);
1241 path->leave_spinning = leave_spinning;
1242
1243 if (ret)
1244 return ERR_PTR(ret);
1245
1246 return dest + bytes_left;
1247 }
1248
1249 /*
1250 * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
1251 * of the path are separated by '/' and the path is guaranteed to be
1252 * 0-terminated. the path is only given within the current file system.
1253 * Therefore, it never starts with a '/'. the caller is responsible to provide
1254 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1255 * the start point of the resulting string is returned. this pointer is within
1256 * dest, normally.
1257 * in case the path buffer would overflow, the pointer is decremented further
1258 * as if output was written to the buffer, though no more output is actually
1259 * generated. that way, the caller can determine how much space would be
1260 * required for the path to fit into the buffer. in that case, the returned
1261 * value will be smaller than dest. callers must check this!
1262 */
1263 char *btrfs_iref_to_path(struct btrfs_root *fs_root,
1264 struct btrfs_path *path,
1265 struct btrfs_inode_ref *iref,
1266 struct extent_buffer *eb_in, u64 parent,
1267 char *dest, u32 size)
1268 {
1269 return ref_to_path(fs_root, path,
1270 btrfs_inode_ref_name_len(eb_in, iref),
1271 (unsigned long)(iref + 1),
1272 eb_in, parent, dest, size);
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 list_head data_refs = LIST_HEAD_INIT(data_refs);
1463 struct list_head shared_refs = LIST_HEAD_INIT(shared_refs);
1464 struct btrfs_trans_handle *trans;
1465 struct ulist *refs = NULL;
1466 struct ulist *roots = NULL;
1467 struct ulist_node *ref_node = NULL;
1468 struct ulist_node *root_node = NULL;
1469 struct seq_list tree_mod_seq_elem = {};
1470 struct ulist_iterator ref_uiter;
1471 struct ulist_iterator root_uiter;
1472
1473 pr_debug("resolving all inodes for extent %llu\n",
1474 extent_item_objectid);
1475
1476 if (search_commit_root) {
1477 trans = BTRFS_BACKREF_SEARCH_COMMIT_ROOT;
1478 } else {
1479 trans = btrfs_join_transaction(fs_info->extent_root);
1480 if (IS_ERR(trans))
1481 return PTR_ERR(trans);
1482 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1483 }
1484
1485 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1486 tree_mod_seq_elem.seq, &refs,
1487 &extent_item_pos);
1488 if (ret)
1489 goto out;
1490
1491 ULIST_ITER_INIT(&ref_uiter);
1492 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1493 ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
1494 tree_mod_seq_elem.seq, &roots);
1495 if (ret)
1496 break;
1497 ULIST_ITER_INIT(&root_uiter);
1498 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1499 pr_debug("root %llu references leaf %llu, data list "
1500 "%#llx\n", root_node->val, ref_node->val,
1501 (long long)ref_node->aux);
1502 ret = iterate_leaf_refs((struct extent_inode_elem *)
1503 (uintptr_t)ref_node->aux,
1504 root_node->val,
1505 extent_item_objectid,
1506 iterate, ctx);
1507 }
1508 ulist_free(roots);
1509 roots = NULL;
1510 }
1511
1512 free_leaf_list(refs);
1513 ulist_free(roots);
1514 out:
1515 if (!search_commit_root) {
1516 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1517 btrfs_end_transaction(trans, fs_info->extent_root);
1518 }
1519
1520 return ret;
1521 }
1522
1523 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1524 struct btrfs_path *path,
1525 iterate_extent_inodes_t *iterate, void *ctx)
1526 {
1527 int ret;
1528 u64 extent_item_pos;
1529 u64 flags = 0;
1530 struct btrfs_key found_key;
1531 int search_commit_root = path->search_commit_root;
1532
1533 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1534 btrfs_release_path(path);
1535 if (ret < 0)
1536 return ret;
1537 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1538 return -EINVAL;
1539
1540 extent_item_pos = logical - found_key.objectid;
1541 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1542 extent_item_pos, search_commit_root,
1543 iterate, ctx);
1544
1545 return ret;
1546 }
1547
1548 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1549 struct extent_buffer *eb, void *ctx);
1550
1551 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1552 struct btrfs_path *path,
1553 iterate_irefs_t *iterate, void *ctx)
1554 {
1555 int ret = 0;
1556 int slot;
1557 u32 cur;
1558 u32 len;
1559 u32 name_len;
1560 u64 parent = 0;
1561 int found = 0;
1562 struct extent_buffer *eb;
1563 struct btrfs_item *item;
1564 struct btrfs_inode_ref *iref;
1565 struct btrfs_key found_key;
1566
1567 while (!ret) {
1568 path->leave_spinning = 1;
1569 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1570 &found_key);
1571 if (ret < 0)
1572 break;
1573 if (ret) {
1574 ret = found ? 0 : -ENOENT;
1575 break;
1576 }
1577 ++found;
1578
1579 parent = found_key.offset;
1580 slot = path->slots[0];
1581 eb = path->nodes[0];
1582 /* make sure we can use eb after releasing the path */
1583 atomic_inc(&eb->refs);
1584 btrfs_tree_read_lock(eb);
1585 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1586 btrfs_release_path(path);
1587
1588 item = btrfs_item_nr(eb, slot);
1589 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1590
1591 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1592 name_len = btrfs_inode_ref_name_len(eb, iref);
1593 /* path must be released before calling iterate()! */
1594 pr_debug("following ref at offset %u for inode %llu in "
1595 "tree %llu\n", cur,
1596 (unsigned long long)found_key.objectid,
1597 (unsigned long long)fs_root->objectid);
1598 ret = iterate(parent, name_len,
1599 (unsigned long)(iref + 1), eb, ctx);
1600 if (ret)
1601 break;
1602 len = sizeof(*iref) + name_len;
1603 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1604 }
1605 btrfs_tree_read_unlock_blocking(eb);
1606 free_extent_buffer(eb);
1607 }
1608
1609 btrfs_release_path(path);
1610
1611 return ret;
1612 }
1613
1614 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1615 struct btrfs_path *path,
1616 iterate_irefs_t *iterate, void *ctx)
1617 {
1618 int ret;
1619 int slot;
1620 u64 offset = 0;
1621 u64 parent;
1622 int found = 0;
1623 struct extent_buffer *eb;
1624 struct btrfs_inode_extref *extref;
1625 struct extent_buffer *leaf;
1626 u32 item_size;
1627 u32 cur_offset;
1628 unsigned long ptr;
1629
1630 while (1) {
1631 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1632 &offset);
1633 if (ret < 0)
1634 break;
1635 if (ret) {
1636 ret = found ? 0 : -ENOENT;
1637 break;
1638 }
1639 ++found;
1640
1641 slot = path->slots[0];
1642 eb = path->nodes[0];
1643 /* make sure we can use eb after releasing the path */
1644 atomic_inc(&eb->refs);
1645
1646 btrfs_tree_read_lock(eb);
1647 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1648 btrfs_release_path(path);
1649
1650 leaf = path->nodes[0];
1651 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1652 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1653 cur_offset = 0;
1654
1655 while (cur_offset < item_size) {
1656 u32 name_len;
1657
1658 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1659 parent = btrfs_inode_extref_parent(eb, extref);
1660 name_len = btrfs_inode_extref_name_len(eb, extref);
1661 ret = iterate(parent, name_len,
1662 (unsigned long)&extref->name, eb, ctx);
1663 if (ret)
1664 break;
1665
1666 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1667 cur_offset += sizeof(*extref);
1668 }
1669 btrfs_tree_read_unlock_blocking(eb);
1670 free_extent_buffer(eb);
1671
1672 offset++;
1673 }
1674
1675 btrfs_release_path(path);
1676
1677 return ret;
1678 }
1679
1680 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1681 struct btrfs_path *path, iterate_irefs_t *iterate,
1682 void *ctx)
1683 {
1684 int ret;
1685 int found_refs = 0;
1686
1687 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1688 if (!ret)
1689 ++found_refs;
1690 else if (ret != -ENOENT)
1691 return ret;
1692
1693 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1694 if (ret == -ENOENT && found_refs)
1695 return 0;
1696
1697 return ret;
1698 }
1699
1700 /*
1701 * returns 0 if the path could be dumped (probably truncated)
1702 * returns <0 in case of an error
1703 */
1704 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1705 struct extent_buffer *eb, void *ctx)
1706 {
1707 struct inode_fs_paths *ipath = ctx;
1708 char *fspath;
1709 char *fspath_min;
1710 int i = ipath->fspath->elem_cnt;
1711 const int s_ptr = sizeof(char *);
1712 u32 bytes_left;
1713
1714 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1715 ipath->fspath->bytes_left - s_ptr : 0;
1716
1717 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1718 fspath = ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1719 name_off, eb, inum, fspath_min,
1720 bytes_left);
1721 if (IS_ERR(fspath))
1722 return PTR_ERR(fspath);
1723
1724 if (fspath > fspath_min) {
1725 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1726 ++ipath->fspath->elem_cnt;
1727 ipath->fspath->bytes_left = fspath - fspath_min;
1728 } else {
1729 ++ipath->fspath->elem_missed;
1730 ipath->fspath->bytes_missing += fspath_min - fspath;
1731 ipath->fspath->bytes_left = 0;
1732 }
1733
1734 return 0;
1735 }
1736
1737 /*
1738 * this dumps all file system paths to the inode into the ipath struct, provided
1739 * is has been created large enough. each path is zero-terminated and accessed
1740 * from ipath->fspath->val[i].
1741 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1742 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1743 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1744 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1745 * have been needed to return all paths.
1746 */
1747 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1748 {
1749 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1750 inode_to_path, ipath);
1751 }
1752
1753 struct btrfs_data_container *init_data_container(u32 total_bytes)
1754 {
1755 struct btrfs_data_container *data;
1756 size_t alloc_bytes;
1757
1758 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1759 data = vmalloc(alloc_bytes);
1760 if (!data)
1761 return ERR_PTR(-ENOMEM);
1762
1763 if (total_bytes >= sizeof(*data)) {
1764 data->bytes_left = total_bytes - sizeof(*data);
1765 data->bytes_missing = 0;
1766 } else {
1767 data->bytes_missing = sizeof(*data) - total_bytes;
1768 data->bytes_left = 0;
1769 }
1770
1771 data->elem_cnt = 0;
1772 data->elem_missed = 0;
1773
1774 return data;
1775 }
1776
1777 /*
1778 * allocates space to return multiple file system paths for an inode.
1779 * total_bytes to allocate are passed, note that space usable for actual path
1780 * information will be total_bytes - sizeof(struct inode_fs_paths).
1781 * the returned pointer must be freed with free_ipath() in the end.
1782 */
1783 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1784 struct btrfs_path *path)
1785 {
1786 struct inode_fs_paths *ifp;
1787 struct btrfs_data_container *fspath;
1788
1789 fspath = init_data_container(total_bytes);
1790 if (IS_ERR(fspath))
1791 return (void *)fspath;
1792
1793 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1794 if (!ifp) {
1795 kfree(fspath);
1796 return ERR_PTR(-ENOMEM);
1797 }
1798
1799 ifp->btrfs_path = path;
1800 ifp->fspath = fspath;
1801 ifp->fs_root = fs_root;
1802
1803 return ifp;
1804 }
1805
1806 void free_ipath(struct inode_fs_paths *ipath)
1807 {
1808 if (!ipath)
1809 return;
1810 vfree(ipath->fspath);
1811 kfree(ipath);
1812 }
Linux 2.6 libata-dev (mirror)