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