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HID: hiddev: Fix slab-out-of-bounds write in hiddev_ioctl_usage()
[linux/fpc-iii.git] / fs / btrfs / backref.c
blob228bfa19b745d6877f2f0ebb16afaab7e674ed79
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 /* Just an arbitrary number so we can be sure this happened */
29 #define BACKREF_FOUND_SHARED 6
30
31 struct extent_inode_elem {
32 u64 inum;
33 u64 offset;
34 struct extent_inode_elem *next;
35 };
36
37 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
38 struct btrfs_file_extent_item *fi,
39 u64 extent_item_pos,
40 struct extent_inode_elem **eie)
41 {
42 u64 offset = 0;
43 struct extent_inode_elem *e;
44
45 if (!btrfs_file_extent_compression(eb, fi) &&
46 !btrfs_file_extent_encryption(eb, fi) &&
47 !btrfs_file_extent_other_encoding(eb, fi)) {
48 u64 data_offset;
49 u64 data_len;
50
51 data_offset = btrfs_file_extent_offset(eb, fi);
52 data_len = btrfs_file_extent_num_bytes(eb, fi);
53
54 if (extent_item_pos < data_offset ||
55 extent_item_pos >= data_offset + data_len)
56 return 1;
57 offset = extent_item_pos - data_offset;
58 }
59
60 e = kmalloc(sizeof(*e), GFP_NOFS);
61 if (!e)
62 return -ENOMEM;
63
64 e->next = *eie;
65 e->inum = key->objectid;
66 e->offset = key->offset + offset;
67 *eie = e;
68
69 return 0;
70 }
71
72 static void free_inode_elem_list(struct extent_inode_elem *eie)
73 {
74 struct extent_inode_elem *eie_next;
75
76 for (; eie; eie = eie_next) {
77 eie_next = eie->next;
78 kfree(eie);
79 }
80 }
81
82 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
83 u64 extent_item_pos,
84 struct extent_inode_elem **eie)
85 {
86 u64 disk_byte;
87 struct btrfs_key key;
88 struct btrfs_file_extent_item *fi;
89 int slot;
90 int nritems;
91 int extent_type;
92 int ret;
93
94 /*
95 * from the shared data ref, we only have the leaf but we need
96 * the key. thus, we must look into all items and see that we
97 * find one (some) with a reference to our extent item.
98 */
99 nritems = btrfs_header_nritems(eb);
100 for (slot = 0; slot < nritems; ++slot) {
101 btrfs_item_key_to_cpu(eb, &key, slot);
102 if (key.type != BTRFS_EXTENT_DATA_KEY)
103 continue;
104 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
105 extent_type = btrfs_file_extent_type(eb, fi);
106 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
107 continue;
108 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
109 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
110 if (disk_byte != wanted_disk_byte)
111 continue;
112
113 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
114 if (ret < 0)
115 return ret;
116 }
117
118 return 0;
119 }
120
121 /*
122 * this structure records all encountered refs on the way up to the root
123 */
124 struct __prelim_ref {
125 struct list_head list;
126 u64 root_id;
127 struct btrfs_key key_for_search;
128 int level;
129 int count;
130 struct extent_inode_elem *inode_list;
131 u64 parent;
132 u64 wanted_disk_byte;
133 };
134
135 static struct kmem_cache *btrfs_prelim_ref_cache;
136
137 int __init btrfs_prelim_ref_init(void)
138 {
139 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
140 sizeof(struct __prelim_ref),
141 0,
142 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
143 NULL);
144 if (!btrfs_prelim_ref_cache)
145 return -ENOMEM;
146 return 0;
147 }
148
149 void btrfs_prelim_ref_exit(void)
150 {
151 if (btrfs_prelim_ref_cache)
152 kmem_cache_destroy(btrfs_prelim_ref_cache);
153 }
154
155 /*
156 * the rules for all callers of this function are:
157 * - obtaining the parent is the goal
158 * - if you add a key, you must know that it is a correct key
159 * - if you cannot add the parent or a correct key, then we will look into the
160 * block later to set a correct key
161 *
162 * delayed refs
163 * ============
164 * backref type | shared | indirect | shared | indirect
165 * information | tree | tree | data | data
166 * --------------------+--------+----------+--------+----------
167 * parent logical | y | - | - | -
168 * key to resolve | - | y | y | y
169 * tree block logical | - | - | - | -
170 * root for resolving | y | y | y | y
171 *
172 * - column 1: we've the parent -> done
173 * - column 2, 3, 4: we use the key to find the parent
174 *
175 * on disk refs (inline or keyed)
176 * ==============================
177 * backref type | shared | indirect | shared | indirect
178 * information | tree | tree | data | data
179 * --------------------+--------+----------+--------+----------
180 * parent logical | y | - | y | -
181 * key to resolve | - | - | - | y
182 * tree block logical | y | y | y | y
183 * root for resolving | - | y | y | y
184 *
185 * - column 1, 3: we've the parent -> done
186 * - column 2: we take the first key from the block to find the parent
187 * (see __add_missing_keys)
188 * - column 4: we use the key to find the parent
189 *
190 * additional information that's available but not required to find the parent
191 * block might help in merging entries to gain some speed.
192 */
193
194 static int __add_prelim_ref(struct list_head *head, u64 root_id,
195 struct btrfs_key *key, int level,
196 u64 parent, u64 wanted_disk_byte, int count,
197 gfp_t gfp_mask)
198 {
199 struct __prelim_ref *ref;
200
201 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
202 return 0;
203
204 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
205 if (!ref)
206 return -ENOMEM;
207
208 ref->root_id = root_id;
209 if (key) {
210 ref->key_for_search = *key;
211 /*
212 * We can often find data backrefs with an offset that is too
213 * large (>= LLONG_MAX, maximum allowed file offset) due to
214 * underflows when subtracting a file's offset with the data
215 * offset of its corresponding extent data item. This can
216 * happen for example in the clone ioctl.
217 * So if we detect such case we set the search key's offset to
218 * zero to make sure we will find the matching file extent item
219 * at add_all_parents(), otherwise we will miss it because the
220 * offset taken form the backref is much larger then the offset
221 * of the file extent item. This can make us scan a very large
222 * number of file extent items, but at least it will not make
223 * us miss any.
224 * This is an ugly workaround for a behaviour that should have
225 * never existed, but it does and a fix for the clone ioctl
226 * would touch a lot of places, cause backwards incompatibility
227 * and would not fix the problem for extents cloned with older
228 * kernels.
229 */
230 if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY &&
231 ref->key_for_search.offset >= LLONG_MAX)
232 ref->key_for_search.offset = 0;
233 } else {
234 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
235 }
236
237 ref->inode_list = NULL;
238 ref->level = level;
239 ref->count = count;
240 ref->parent = parent;
241 ref->wanted_disk_byte = wanted_disk_byte;
242 list_add_tail(&ref->list, head);
243
244 return 0;
245 }
246
247 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
248 struct ulist *parents, struct __prelim_ref *ref,
249 int level, u64 time_seq, const u64 *extent_item_pos,
250 u64 total_refs)
251 {
252 int ret = 0;
253 int slot;
254 struct extent_buffer *eb;
255 struct btrfs_key key;
256 struct btrfs_key *key_for_search = &ref->key_for_search;
257 struct btrfs_file_extent_item *fi;
258 struct extent_inode_elem *eie = NULL, *old = NULL;
259 u64 disk_byte;
260 u64 wanted_disk_byte = ref->wanted_disk_byte;
261 u64 count = 0;
262
263 if (level != 0) {
264 eb = path->nodes[level];
265 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
266 if (ret < 0)
267 return ret;
268 return 0;
269 }
270
271 /*
272 * We normally enter this function with the path already pointing to
273 * the first item to check. But sometimes, we may enter it with
274 * slot==nritems. In that case, go to the next leaf before we continue.
275 */
276 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
277 if (time_seq == (u64)-1)
278 ret = btrfs_next_leaf(root, path);
279 else
280 ret = btrfs_next_old_leaf(root, path, time_seq);
281 }
282
283 while (!ret && count < total_refs) {
284 eb = path->nodes[0];
285 slot = path->slots[0];
286
287 btrfs_item_key_to_cpu(eb, &key, slot);
288
289 if (key.objectid != key_for_search->objectid ||
290 key.type != BTRFS_EXTENT_DATA_KEY)
291 break;
292
293 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
294 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
295
296 if (disk_byte == wanted_disk_byte) {
297 eie = NULL;
298 old = NULL;
299 count++;
300 if (extent_item_pos) {
301 ret = check_extent_in_eb(&key, eb, fi,
302 *extent_item_pos,
303 &eie);
304 if (ret < 0)
305 break;
306 }
307 if (ret > 0)
308 goto next;
309 ret = ulist_add_merge_ptr(parents, eb->start,
310 eie, (void **)&old, GFP_NOFS);
311 if (ret < 0)
312 break;
313 if (!ret && extent_item_pos) {
314 while (old->next)
315 old = old->next;
316 old->next = eie;
317 }
318 eie = NULL;
319 }
320 next:
321 if (time_seq == (u64)-1)
322 ret = btrfs_next_item(root, path);
323 else
324 ret = btrfs_next_old_item(root, path, time_seq);
325 }
326
327 if (ret > 0)
328 ret = 0;
329 else if (ret < 0)
330 free_inode_elem_list(eie);
331 return ret;
332 }
333
334 /*
335 * resolve an indirect backref in the form (root_id, key, level)
336 * to a logical address
337 */
338 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
339 struct btrfs_path *path, u64 time_seq,
340 struct __prelim_ref *ref,
341 struct ulist *parents,
342 const u64 *extent_item_pos, u64 total_refs)
343 {
344 struct btrfs_root *root;
345 struct btrfs_key root_key;
346 struct extent_buffer *eb;
347 int ret = 0;
348 int root_level;
349 int level = ref->level;
350 int index;
351
352 root_key.objectid = ref->root_id;
353 root_key.type = BTRFS_ROOT_ITEM_KEY;
354 root_key.offset = (u64)-1;
355
356 index = srcu_read_lock(&fs_info->subvol_srcu);
357
358 root = btrfs_get_fs_root(fs_info, &root_key, false);
359 if (IS_ERR(root)) {
360 srcu_read_unlock(&fs_info->subvol_srcu, index);
361 ret = PTR_ERR(root);
362 goto out;
363 }
364
365 if (btrfs_test_is_dummy_root(root)) {
366 srcu_read_unlock(&fs_info->subvol_srcu, index);
367 ret = -ENOENT;
368 goto out;
369 }
370
371 if (path->search_commit_root)
372 root_level = btrfs_header_level(root->commit_root);
373 else if (time_seq == (u64)-1)
374 root_level = btrfs_header_level(root->node);
375 else
376 root_level = btrfs_old_root_level(root, time_seq);
377
378 if (root_level + 1 == level) {
379 srcu_read_unlock(&fs_info->subvol_srcu, index);
380 goto out;
381 }
382
383 path->lowest_level = level;
384 if (time_seq == (u64)-1)
385 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path,
386 0, 0);
387 else
388 ret = btrfs_search_old_slot(root, &ref->key_for_search, path,
389 time_seq);
390
391 /* root node has been locked, we can release @subvol_srcu safely here */
392 srcu_read_unlock(&fs_info->subvol_srcu, index);
393
394 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
395 "%d for key (%llu %u %llu)\n",
396 ref->root_id, level, ref->count, ret,
397 ref->key_for_search.objectid, ref->key_for_search.type,
398 ref->key_for_search.offset);
399 if (ret < 0)
400 goto out;
401
402 eb = path->nodes[level];
403 while (!eb) {
404 if (WARN_ON(!level)) {
405 ret = 1;
406 goto out;
407 }
408 level--;
409 eb = path->nodes[level];
410 }
411
412 ret = add_all_parents(root, path, parents, ref, level, time_seq,
413 extent_item_pos, total_refs);
414 out:
415 path->lowest_level = 0;
416 btrfs_release_path(path);
417 return ret;
418 }
419
420 /*
421 * resolve all indirect backrefs from the list
422 */
423 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
424 struct btrfs_path *path, u64 time_seq,
425 struct list_head *head,
426 const u64 *extent_item_pos, u64 total_refs,
427 u64 root_objectid)
428 {
429 int err;
430 int ret = 0;
431 struct __prelim_ref *ref;
432 struct __prelim_ref *ref_safe;
433 struct __prelim_ref *new_ref;
434 struct ulist *parents;
435 struct ulist_node *node;
436 struct ulist_iterator uiter;
437
438 parents = ulist_alloc(GFP_NOFS);
439 if (!parents)
440 return -ENOMEM;
441
442 /*
443 * _safe allows us to insert directly after the current item without
444 * iterating over the newly inserted items.
445 * we're also allowed to re-assign ref during iteration.
446 */
447 list_for_each_entry_safe(ref, ref_safe, head, list) {
448 if (ref->parent) /* already direct */
449 continue;
450 if (ref->count == 0)
451 continue;
452 if (root_objectid && ref->root_id != root_objectid) {
453 ret = BACKREF_FOUND_SHARED;
454 goto out;
455 }
456 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
457 parents, extent_item_pos,
458 total_refs);
459 /*
460 * we can only tolerate ENOENT,otherwise,we should catch error
461 * and return directly.
462 */
463 if (err == -ENOENT) {
464 continue;
465 } else if (err) {
466 ret = err;
467 goto out;
468 }
469
470 /* we put the first parent into the ref at hand */
471 ULIST_ITER_INIT(&uiter);
472 node = ulist_next(parents, &uiter);
473 ref->parent = node ? node->val : 0;
474 ref->inode_list = node ?
475 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
476
477 /* additional parents require new refs being added here */
478 while ((node = ulist_next(parents, &uiter))) {
479 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
480 GFP_NOFS);
481 if (!new_ref) {
482 ret = -ENOMEM;
483 goto out;
484 }
485 memcpy(new_ref, ref, sizeof(*ref));
486 new_ref->parent = node->val;
487 new_ref->inode_list = (struct extent_inode_elem *)
488 (uintptr_t)node->aux;
489 list_add(&new_ref->list, &ref->list);
490 }
491 ulist_reinit(parents);
492 }
493 out:
494 ulist_free(parents);
495 return ret;
496 }
497
498 static inline int ref_for_same_block(struct __prelim_ref *ref1,
499 struct __prelim_ref *ref2)
500 {
501 if (ref1->level != ref2->level)
502 return 0;
503 if (ref1->root_id != ref2->root_id)
504 return 0;
505 if (ref1->key_for_search.type != ref2->key_for_search.type)
506 return 0;
507 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
508 return 0;
509 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
510 return 0;
511 if (ref1->parent != ref2->parent)
512 return 0;
513
514 return 1;
515 }
516
517 /*
518 * read tree blocks and add keys where required.
519 */
520 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
521 struct list_head *head)
522 {
523 struct list_head *pos;
524 struct extent_buffer *eb;
525
526 list_for_each(pos, head) {
527 struct __prelim_ref *ref;
528 ref = list_entry(pos, struct __prelim_ref, list);
529
530 if (ref->parent)
531 continue;
532 if (ref->key_for_search.type)
533 continue;
534 BUG_ON(!ref->wanted_disk_byte);
535 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
536 0);
537 if (IS_ERR(eb)) {
538 return PTR_ERR(eb);
539 } else if (!extent_buffer_uptodate(eb)) {
540 free_extent_buffer(eb);
541 return -EIO;
542 }
543 btrfs_tree_read_lock(eb);
544 if (btrfs_header_level(eb) == 0)
545 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
546 else
547 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
548 btrfs_tree_read_unlock(eb);
549 free_extent_buffer(eb);
550 }
551 return 0;
552 }
553
554 /*
555 * merge backrefs and adjust counts accordingly
556 *
557 * mode = 1: merge identical keys, if key is set
558 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
559 * additionally, we could even add a key range for the blocks we
560 * looked into to merge even more (-> replace unresolved refs by those
561 * having a parent).
562 * mode = 2: merge identical parents
563 */
564 static void __merge_refs(struct list_head *head, int mode)
565 {
566 struct list_head *pos1;
567
568 list_for_each(pos1, head) {
569 struct list_head *n2;
570 struct list_head *pos2;
571 struct __prelim_ref *ref1;
572
573 ref1 = list_entry(pos1, struct __prelim_ref, list);
574
575 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
576 pos2 = n2, n2 = pos2->next) {
577 struct __prelim_ref *ref2;
578 struct __prelim_ref *xchg;
579 struct extent_inode_elem *eie;
580
581 ref2 = list_entry(pos2, struct __prelim_ref, list);
582
583 if (!ref_for_same_block(ref1, ref2))
584 continue;
585 if (mode == 1) {
586 if (!ref1->parent && ref2->parent) {
587 xchg = ref1;
588 ref1 = ref2;
589 ref2 = xchg;
590 }
591 } else {
592 if (ref1->parent != ref2->parent)
593 continue;
594 }
595
596 eie = ref1->inode_list;
597 while (eie && eie->next)
598 eie = eie->next;
599 if (eie)
600 eie->next = ref2->inode_list;
601 else
602 ref1->inode_list = ref2->inode_list;
603 ref1->count += ref2->count;
604
605 list_del(&ref2->list);
606 kmem_cache_free(btrfs_prelim_ref_cache, ref2);
607 }
608
609 }
610 }
611
612 /*
613 * add all currently queued delayed refs from this head whose seq nr is
614 * smaller or equal that seq to the list
615 */
616 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
617 struct list_head *prefs, u64 *total_refs,
618 u64 inum)
619 {
620 struct btrfs_delayed_ref_node *node;
621 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
622 struct btrfs_key key;
623 struct btrfs_key op_key = {0};
624 int sgn;
625 int ret = 0;
626
627 if (extent_op && extent_op->update_key)
628 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
629
630 spin_lock(&head->lock);
631 list_for_each_entry(node, &head->ref_list, list) {
632 if (node->seq > seq)
633 continue;
634
635 switch (node->action) {
636 case BTRFS_ADD_DELAYED_EXTENT:
637 case BTRFS_UPDATE_DELAYED_HEAD:
638 WARN_ON(1);
639 continue;
640 case BTRFS_ADD_DELAYED_REF:
641 sgn = 1;
642 break;
643 case BTRFS_DROP_DELAYED_REF:
644 sgn = -1;
645 break;
646 default:
647 BUG_ON(1);
648 }
649 *total_refs += (node->ref_mod * sgn);
650 switch (node->type) {
651 case BTRFS_TREE_BLOCK_REF_KEY: {
652 struct btrfs_delayed_tree_ref *ref;
653
654 ref = btrfs_delayed_node_to_tree_ref(node);
655 ret = __add_prelim_ref(prefs, ref->root, &op_key,
656 ref->level + 1, 0, node->bytenr,
657 node->ref_mod * sgn, GFP_ATOMIC);
658 break;
659 }
660 case BTRFS_SHARED_BLOCK_REF_KEY: {
661 struct btrfs_delayed_tree_ref *ref;
662
663 ref = btrfs_delayed_node_to_tree_ref(node);
664 ret = __add_prelim_ref(prefs, 0, NULL,
665 ref->level + 1, ref->parent,
666 node->bytenr,
667 node->ref_mod * sgn, GFP_ATOMIC);
668 break;
669 }
670 case BTRFS_EXTENT_DATA_REF_KEY: {
671 struct btrfs_delayed_data_ref *ref;
672 ref = btrfs_delayed_node_to_data_ref(node);
673
674 key.objectid = ref->objectid;
675 key.type = BTRFS_EXTENT_DATA_KEY;
676 key.offset = ref->offset;
677
678 /*
679 * Found a inum that doesn't match our known inum, we
680 * know it's shared.
681 */
682 if (inum && ref->objectid != inum) {
683 ret = BACKREF_FOUND_SHARED;
684 break;
685 }
686
687 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
688 node->bytenr,
689 node->ref_mod * sgn, GFP_ATOMIC);
690 break;
691 }
692 case BTRFS_SHARED_DATA_REF_KEY: {
693 struct btrfs_delayed_data_ref *ref;
694
695 ref = btrfs_delayed_node_to_data_ref(node);
696 ret = __add_prelim_ref(prefs, 0, NULL, 0,
697 ref->parent, node->bytenr,
698 node->ref_mod * sgn, GFP_ATOMIC);
699 break;
700 }
701 default:
702 WARN_ON(1);
703 }
704 if (ret)
705 break;
706 }
707 spin_unlock(&head->lock);
708 return ret;
709 }
710
711 /*
712 * add all inline backrefs for bytenr to the list
713 */
714 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
715 struct btrfs_path *path, u64 bytenr,
716 int *info_level, struct list_head *prefs,
717 u64 *total_refs, u64 inum)
718 {
719 int ret = 0;
720 int slot;
721 struct extent_buffer *leaf;
722 struct btrfs_key key;
723 struct btrfs_key found_key;
724 unsigned long ptr;
725 unsigned long end;
726 struct btrfs_extent_item *ei;
727 u64 flags;
728 u64 item_size;
729
730 /*
731 * enumerate all inline refs
732 */
733 leaf = path->nodes[0];
734 slot = path->slots[0];
735
736 item_size = btrfs_item_size_nr(leaf, slot);
737 BUG_ON(item_size < sizeof(*ei));
738
739 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
740 flags = btrfs_extent_flags(leaf, ei);
741 *total_refs += btrfs_extent_refs(leaf, ei);
742 btrfs_item_key_to_cpu(leaf, &found_key, slot);
743
744 ptr = (unsigned long)(ei + 1);
745 end = (unsigned long)ei + item_size;
746
747 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
748 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
749 struct btrfs_tree_block_info *info;
750
751 info = (struct btrfs_tree_block_info *)ptr;
752 *info_level = btrfs_tree_block_level(leaf, info);
753 ptr += sizeof(struct btrfs_tree_block_info);
754 BUG_ON(ptr > end);
755 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
756 *info_level = found_key.offset;
757 } else {
758 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
759 }
760
761 while (ptr < end) {
762 struct btrfs_extent_inline_ref *iref;
763 u64 offset;
764 int type;
765
766 iref = (struct btrfs_extent_inline_ref *)ptr;
767 type = btrfs_extent_inline_ref_type(leaf, iref);
768 offset = btrfs_extent_inline_ref_offset(leaf, iref);
769
770 switch (type) {
771 case BTRFS_SHARED_BLOCK_REF_KEY:
772 ret = __add_prelim_ref(prefs, 0, NULL,
773 *info_level + 1, offset,
774 bytenr, 1, GFP_NOFS);
775 break;
776 case BTRFS_SHARED_DATA_REF_KEY: {
777 struct btrfs_shared_data_ref *sdref;
778 int count;
779
780 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
781 count = btrfs_shared_data_ref_count(leaf, sdref);
782 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
783 bytenr, count, GFP_NOFS);
784 break;
785 }
786 case BTRFS_TREE_BLOCK_REF_KEY:
787 ret = __add_prelim_ref(prefs, offset, NULL,
788 *info_level + 1, 0,
789 bytenr, 1, GFP_NOFS);
790 break;
791 case BTRFS_EXTENT_DATA_REF_KEY: {
792 struct btrfs_extent_data_ref *dref;
793 int count;
794 u64 root;
795
796 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
797 count = btrfs_extent_data_ref_count(leaf, dref);
798 key.objectid = btrfs_extent_data_ref_objectid(leaf,
799 dref);
800 key.type = BTRFS_EXTENT_DATA_KEY;
801 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
802
803 if (inum && key.objectid != inum) {
804 ret = BACKREF_FOUND_SHARED;
805 break;
806 }
807
808 root = btrfs_extent_data_ref_root(leaf, dref);
809 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
810 bytenr, count, GFP_NOFS);
811 break;
812 }
813 default:
814 WARN_ON(1);
815 }
816 if (ret)
817 return ret;
818 ptr += btrfs_extent_inline_ref_size(type);
819 }
820
821 return 0;
822 }
823
824 /*
825 * add all non-inline backrefs for bytenr to the list
826 */
827 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
828 struct btrfs_path *path, u64 bytenr,
829 int info_level, struct list_head *prefs, u64 inum)
830 {
831 struct btrfs_root *extent_root = fs_info->extent_root;
832 int ret;
833 int slot;
834 struct extent_buffer *leaf;
835 struct btrfs_key key;
836
837 while (1) {
838 ret = btrfs_next_item(extent_root, path);
839 if (ret < 0)
840 break;
841 if (ret) {
842 ret = 0;
843 break;
844 }
845
846 slot = path->slots[0];
847 leaf = path->nodes[0];
848 btrfs_item_key_to_cpu(leaf, &key, slot);
849
850 if (key.objectid != bytenr)
851 break;
852 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
853 continue;
854 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
855 break;
856
857 switch (key.type) {
858 case BTRFS_SHARED_BLOCK_REF_KEY:
859 ret = __add_prelim_ref(prefs, 0, NULL,
860 info_level + 1, key.offset,
861 bytenr, 1, GFP_NOFS);
862 break;
863 case BTRFS_SHARED_DATA_REF_KEY: {
864 struct btrfs_shared_data_ref *sdref;
865 int count;
866
867 sdref = btrfs_item_ptr(leaf, slot,
868 struct btrfs_shared_data_ref);
869 count = btrfs_shared_data_ref_count(leaf, sdref);
870 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
871 bytenr, count, GFP_NOFS);
872 break;
873 }
874 case BTRFS_TREE_BLOCK_REF_KEY:
875 ret = __add_prelim_ref(prefs, key.offset, NULL,
876 info_level + 1, 0,
877 bytenr, 1, GFP_NOFS);
878 break;
879 case BTRFS_EXTENT_DATA_REF_KEY: {
880 struct btrfs_extent_data_ref *dref;
881 int count;
882 u64 root;
883
884 dref = btrfs_item_ptr(leaf, slot,
885 struct btrfs_extent_data_ref);
886 count = btrfs_extent_data_ref_count(leaf, dref);
887 key.objectid = btrfs_extent_data_ref_objectid(leaf,
888 dref);
889 key.type = BTRFS_EXTENT_DATA_KEY;
890 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
891
892 if (inum && key.objectid != inum) {
893 ret = BACKREF_FOUND_SHARED;
894 break;
895 }
896
897 root = btrfs_extent_data_ref_root(leaf, dref);
898 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
899 bytenr, count, GFP_NOFS);
900 break;
901 }
902 default:
903 WARN_ON(1);
904 }
905 if (ret)
906 return ret;
907
908 }
909
910 return ret;
911 }
912
913 /*
914 * this adds all existing backrefs (inline backrefs, backrefs and delayed
915 * refs) for the given bytenr to the refs list, merges duplicates and resolves
916 * indirect refs to their parent bytenr.
917 * When roots are found, they're added to the roots list
918 *
919 * NOTE: This can return values > 0
920 *
921 * If time_seq is set to (u64)-1, it will not search delayed_refs, and behave
922 * much like trans == NULL case, the difference only lies in it will not
923 * commit root.
924 * The special case is for qgroup to search roots in commit_transaction().
925 *
926 * FIXME some caching might speed things up
927 */
928 static int find_parent_nodes(struct btrfs_trans_handle *trans,
929 struct btrfs_fs_info *fs_info, u64 bytenr,
930 u64 time_seq, struct ulist *refs,
931 struct ulist *roots, const u64 *extent_item_pos,
932 u64 root_objectid, u64 inum)
933 {
934 struct btrfs_key key;
935 struct btrfs_path *path;
936 struct btrfs_delayed_ref_root *delayed_refs = NULL;
937 struct btrfs_delayed_ref_head *head;
938 int info_level = 0;
939 int ret;
940 struct list_head prefs_delayed;
941 struct list_head prefs;
942 struct __prelim_ref *ref;
943 struct extent_inode_elem *eie = NULL;
944 u64 total_refs = 0;
945
946 INIT_LIST_HEAD(&prefs);
947 INIT_LIST_HEAD(&prefs_delayed);
948
949 key.objectid = bytenr;
950 key.offset = (u64)-1;
951 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
952 key.type = BTRFS_METADATA_ITEM_KEY;
953 else
954 key.type = BTRFS_EXTENT_ITEM_KEY;
955
956 path = btrfs_alloc_path();
957 if (!path)
958 return -ENOMEM;
959 if (!trans) {
960 path->search_commit_root = 1;
961 path->skip_locking = 1;
962 }
963
964 if (time_seq == (u64)-1)
965 path->skip_locking = 1;
966
967 /*
968 * grab both a lock on the path and a lock on the delayed ref head.
969 * We need both to get a consistent picture of how the refs look
970 * at a specified point in time
971 */
972 again:
973 head = NULL;
974
975 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
976 if (ret < 0)
977 goto out;
978 BUG_ON(ret == 0);
979
980 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
981 if (trans && likely(trans->type != __TRANS_DUMMY) &&
982 time_seq != (u64)-1) {
983 #else
984 if (trans && time_seq != (u64)-1) {
985 #endif
986 /*
987 * look if there are updates for this ref queued and lock the
988 * head
989 */
990 delayed_refs = &trans->transaction->delayed_refs;
991 spin_lock(&delayed_refs->lock);
992 head = btrfs_find_delayed_ref_head(trans, bytenr);
993 if (head) {
994 if (!mutex_trylock(&head->mutex)) {
995 atomic_inc(&head->node.refs);
996 spin_unlock(&delayed_refs->lock);
997
998 btrfs_release_path(path);
999
1000 /*
1001 * Mutex was contended, block until it's
1002 * released and try again
1003 */
1004 mutex_lock(&head->mutex);
1005 mutex_unlock(&head->mutex);
1006 btrfs_put_delayed_ref(&head->node);
1007 goto again;
1008 }
1009 spin_unlock(&delayed_refs->lock);
1010 ret = __add_delayed_refs(head, time_seq,
1011 &prefs_delayed, &total_refs,
1012 inum);
1013 mutex_unlock(&head->mutex);
1014 if (ret)
1015 goto out;
1016 } else {
1017 spin_unlock(&delayed_refs->lock);
1018 }
1019 }
1020
1021 if (path->slots[0]) {
1022 struct extent_buffer *leaf;
1023 int slot;
1024
1025 path->slots[0]--;
1026 leaf = path->nodes[0];
1027 slot = path->slots[0];
1028 btrfs_item_key_to_cpu(leaf, &key, slot);
1029 if (key.objectid == bytenr &&
1030 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1031 key.type == BTRFS_METADATA_ITEM_KEY)) {
1032 ret = __add_inline_refs(fs_info, path, bytenr,
1033 &info_level, &prefs,
1034 &total_refs, inum);
1035 if (ret)
1036 goto out;
1037 ret = __add_keyed_refs(fs_info, path, bytenr,
1038 info_level, &prefs, inum);
1039 if (ret)
1040 goto out;
1041 }
1042 }
1043 btrfs_release_path(path);
1044
1045 list_splice_init(&prefs_delayed, &prefs);
1046
1047 ret = __add_missing_keys(fs_info, &prefs);
1048 if (ret)
1049 goto out;
1050
1051 __merge_refs(&prefs, 1);
1052
1053 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
1054 extent_item_pos, total_refs,
1055 root_objectid);
1056 if (ret)
1057 goto out;
1058
1059 __merge_refs(&prefs, 2);
1060
1061 while (!list_empty(&prefs)) {
1062 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1063 WARN_ON(ref->count < 0);
1064 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1065 if (root_objectid && ref->root_id != root_objectid) {
1066 ret = BACKREF_FOUND_SHARED;
1067 goto out;
1068 }
1069
1070 /* no parent == root of tree */
1071 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1072 if (ret < 0)
1073 goto out;
1074 }
1075 if (ref->count && ref->parent) {
1076 if (extent_item_pos && !ref->inode_list &&
1077 ref->level == 0) {
1078 struct extent_buffer *eb;
1079
1080 eb = read_tree_block(fs_info->extent_root,
1081 ref->parent, 0);
1082 if (IS_ERR(eb)) {
1083 ret = PTR_ERR(eb);
1084 goto out;
1085 } else if (!extent_buffer_uptodate(eb)) {
1086 free_extent_buffer(eb);
1087 ret = -EIO;
1088 goto out;
1089 }
1090 btrfs_tree_read_lock(eb);
1091 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1092 ret = find_extent_in_eb(eb, bytenr,
1093 *extent_item_pos, &eie);
1094 btrfs_tree_read_unlock_blocking(eb);
1095 free_extent_buffer(eb);
1096 if (ret < 0)
1097 goto out;
1098 ref->inode_list = eie;
1099 }
1100 ret = ulist_add_merge_ptr(refs, ref->parent,
1101 ref->inode_list,
1102 (void **)&eie, GFP_NOFS);
1103 if (ret < 0)
1104 goto out;
1105 if (!ret && extent_item_pos) {
1106 /*
1107 * we've recorded that parent, so we must extend
1108 * its inode list here
1109 */
1110 BUG_ON(!eie);
1111 while (eie->next)
1112 eie = eie->next;
1113 eie->next = ref->inode_list;
1114 }
1115 eie = NULL;
1116 }
1117 list_del(&ref->list);
1118 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1119 }
1120
1121 out:
1122 btrfs_free_path(path);
1123 while (!list_empty(&prefs)) {
1124 ref = list_first_entry(&prefs, struct __prelim_ref, list);
1125 list_del(&ref->list);
1126 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1127 }
1128 while (!list_empty(&prefs_delayed)) {
1129 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
1130 list);
1131 list_del(&ref->list);
1132 kmem_cache_free(btrfs_prelim_ref_cache, ref);
1133 }
1134 if (ret < 0)
1135 free_inode_elem_list(eie);
1136 return ret;
1137 }
1138
1139 static void free_leaf_list(struct ulist *blocks)
1140 {
1141 struct ulist_node *node = NULL;
1142 struct extent_inode_elem *eie;
1143 struct ulist_iterator uiter;
1144
1145 ULIST_ITER_INIT(&uiter);
1146 while ((node = ulist_next(blocks, &uiter))) {
1147 if (!node->aux)
1148 continue;
1149 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1150 free_inode_elem_list(eie);
1151 node->aux = 0;
1152 }
1153
1154 ulist_free(blocks);
1155 }
1156
1157 /*
1158 * Finds all leafs with a reference to the specified combination of bytenr and
1159 * offset. key_list_head will point to a list of corresponding keys (caller must
1160 * free each list element). The leafs will be stored in the leafs ulist, which
1161 * must be freed with ulist_free.
1162 *
1163 * returns 0 on success, <0 on error
1164 */
1165 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1166 struct btrfs_fs_info *fs_info, u64 bytenr,
1167 u64 time_seq, struct ulist **leafs,
1168 const u64 *extent_item_pos)
1169 {
1170 int ret;
1171
1172 *leafs = ulist_alloc(GFP_NOFS);
1173 if (!*leafs)
1174 return -ENOMEM;
1175
1176 ret = find_parent_nodes(trans, fs_info, bytenr,
1177 time_seq, *leafs, NULL, extent_item_pos, 0, 0);
1178 if (ret < 0 && ret != -ENOENT) {
1179 free_leaf_list(*leafs);
1180 return ret;
1181 }
1182
1183 return 0;
1184 }
1185
1186 /*
1187 * walk all backrefs for a given extent to find all roots that reference this
1188 * extent. Walking a backref means finding all extents that reference this
1189 * extent and in turn walk the backrefs of those, too. Naturally this is a
1190 * recursive process, but here it is implemented in an iterative fashion: We
1191 * find all referencing extents for the extent in question and put them on a
1192 * list. In turn, we find all referencing extents for those, further appending
1193 * to the list. The way we iterate the list allows adding more elements after
1194 * the current while iterating. The process stops when we reach the end of the
1195 * list. Found roots are added to the roots list.
1196 *
1197 * returns 0 on success, < 0 on error.
1198 */
1199 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1200 struct btrfs_fs_info *fs_info, u64 bytenr,
1201 u64 time_seq, struct ulist **roots)
1202 {
1203 struct ulist *tmp;
1204 struct ulist_node *node = NULL;
1205 struct ulist_iterator uiter;
1206 int ret;
1207
1208 tmp = ulist_alloc(GFP_NOFS);
1209 if (!tmp)
1210 return -ENOMEM;
1211 *roots = ulist_alloc(GFP_NOFS);
1212 if (!*roots) {
1213 ulist_free(tmp);
1214 return -ENOMEM;
1215 }
1216
1217 ULIST_ITER_INIT(&uiter);
1218 while (1) {
1219 ret = find_parent_nodes(trans, fs_info, bytenr,
1220 time_seq, tmp, *roots, NULL, 0, 0);
1221 if (ret < 0 && ret != -ENOENT) {
1222 ulist_free(tmp);
1223 ulist_free(*roots);
1224 *roots = NULL;
1225 return ret;
1226 }
1227 node = ulist_next(tmp, &uiter);
1228 if (!node)
1229 break;
1230 bytenr = node->val;
1231 cond_resched();
1232 }
1233
1234 ulist_free(tmp);
1235 return 0;
1236 }
1237
1238 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1239 struct btrfs_fs_info *fs_info, u64 bytenr,
1240 u64 time_seq, struct ulist **roots)
1241 {
1242 int ret;
1243
1244 if (!trans)
1245 down_read(&fs_info->commit_root_sem);
1246 ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
1247 if (!trans)
1248 up_read(&fs_info->commit_root_sem);
1249 return ret;
1250 }
1251
1252 /**
1253 * btrfs_check_shared - tell us whether an extent is shared
1254 *
1255 * @trans: optional trans handle
1256 *
1257 * btrfs_check_shared uses the backref walking code but will short
1258 * circuit as soon as it finds a root or inode that doesn't match the
1259 * one passed in. This provides a significant performance benefit for
1260 * callers (such as fiemap) which want to know whether the extent is
1261 * shared but do not need a ref count.
1262 *
1263 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1264 */
1265 int btrfs_check_shared(struct btrfs_trans_handle *trans,
1266 struct btrfs_fs_info *fs_info, u64 root_objectid,
1267 u64 inum, u64 bytenr)
1268 {
1269 struct ulist *tmp = NULL;
1270 struct ulist *roots = NULL;
1271 struct ulist_iterator uiter;
1272 struct ulist_node *node;
1273 struct seq_list elem = SEQ_LIST_INIT(elem);
1274 int ret = 0;
1275
1276 tmp = ulist_alloc(GFP_NOFS);
1277 roots = ulist_alloc(GFP_NOFS);
1278 if (!tmp || !roots) {
1279 ulist_free(tmp);
1280 ulist_free(roots);
1281 return -ENOMEM;
1282 }
1283
1284 if (trans)
1285 btrfs_get_tree_mod_seq(fs_info, &elem);
1286 else
1287 down_read(&fs_info->commit_root_sem);
1288 ULIST_ITER_INIT(&uiter);
1289 while (1) {
1290 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1291 roots, NULL, root_objectid, inum);
1292 if (ret == BACKREF_FOUND_SHARED) {
1293 /* this is the only condition under which we return 1 */
1294 ret = 1;
1295 break;
1296 }
1297 if (ret < 0 && ret != -ENOENT)
1298 break;
1299 ret = 0;
1300 node = ulist_next(tmp, &uiter);
1301 if (!node)
1302 break;
1303 bytenr = node->val;
1304 cond_resched();
1305 }
1306 if (trans)
1307 btrfs_put_tree_mod_seq(fs_info, &elem);
1308 else
1309 up_read(&fs_info->commit_root_sem);
1310 ulist_free(tmp);
1311 ulist_free(roots);
1312 return ret;
1313 }
1314
1315 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1316 u64 start_off, struct btrfs_path *path,
1317 struct btrfs_inode_extref **ret_extref,
1318 u64 *found_off)
1319 {
1320 int ret, slot;
1321 struct btrfs_key key;
1322 struct btrfs_key found_key;
1323 struct btrfs_inode_extref *extref;
1324 struct extent_buffer *leaf;
1325 unsigned long ptr;
1326
1327 key.objectid = inode_objectid;
1328 key.type = BTRFS_INODE_EXTREF_KEY;
1329 key.offset = start_off;
1330
1331 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1332 if (ret < 0)
1333 return ret;
1334
1335 while (1) {
1336 leaf = path->nodes[0];
1337 slot = path->slots[0];
1338 if (slot >= btrfs_header_nritems(leaf)) {
1339 /*
1340 * If the item at offset is not found,
1341 * btrfs_search_slot will point us to the slot
1342 * where it should be inserted. In our case
1343 * that will be the slot directly before the
1344 * next INODE_REF_KEY_V2 item. In the case
1345 * that we're pointing to the last slot in a
1346 * leaf, we must move one leaf over.
1347 */
1348 ret = btrfs_next_leaf(root, path);
1349 if (ret) {
1350 if (ret >= 1)
1351 ret = -ENOENT;
1352 break;
1353 }
1354 continue;
1355 }
1356
1357 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1358
1359 /*
1360 * Check that we're still looking at an extended ref key for
1361 * this particular objectid. If we have different
1362 * objectid or type then there are no more to be found
1363 * in the tree and we can exit.
1364 */
1365 ret = -ENOENT;
1366 if (found_key.objectid != inode_objectid)
1367 break;
1368 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1369 break;
1370
1371 ret = 0;
1372 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1373 extref = (struct btrfs_inode_extref *)ptr;
1374 *ret_extref = extref;
1375 if (found_off)
1376 *found_off = found_key.offset;
1377 break;
1378 }
1379
1380 return ret;
1381 }
1382
1383 /*
1384 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1385 * Elements of the path are separated by '/' and the path is guaranteed to be
1386 * 0-terminated. the path is only given within the current file system.
1387 * Therefore, it never starts with a '/'. the caller is responsible to provide
1388 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1389 * the start point of the resulting string is returned. this pointer is within
1390 * dest, normally.
1391 * in case the path buffer would overflow, the pointer is decremented further
1392 * as if output was written to the buffer, though no more output is actually
1393 * generated. that way, the caller can determine how much space would be
1394 * required for the path to fit into the buffer. in that case, the returned
1395 * value will be smaller than dest. callers must check this!
1396 */
1397 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1398 u32 name_len, unsigned long name_off,
1399 struct extent_buffer *eb_in, u64 parent,
1400 char *dest, u32 size)
1401 {
1402 int slot;
1403 u64 next_inum;
1404 int ret;
1405 s64 bytes_left = ((s64)size) - 1;
1406 struct extent_buffer *eb = eb_in;
1407 struct btrfs_key found_key;
1408 int leave_spinning = path->leave_spinning;
1409 struct btrfs_inode_ref *iref;
1410
1411 if (bytes_left >= 0)
1412 dest[bytes_left] = '\0';
1413
1414 path->leave_spinning = 1;
1415 while (1) {
1416 bytes_left -= name_len;
1417 if (bytes_left >= 0)
1418 read_extent_buffer(eb, dest + bytes_left,
1419 name_off, name_len);
1420 if (eb != eb_in) {
1421 if (!path->skip_locking)
1422 btrfs_tree_read_unlock_blocking(eb);
1423 free_extent_buffer(eb);
1424 }
1425 ret = btrfs_find_item(fs_root, path, parent, 0,
1426 BTRFS_INODE_REF_KEY, &found_key);
1427 if (ret > 0)
1428 ret = -ENOENT;
1429 if (ret)
1430 break;
1431
1432 next_inum = found_key.offset;
1433
1434 /* regular exit ahead */
1435 if (parent == next_inum)
1436 break;
1437
1438 slot = path->slots[0];
1439 eb = path->nodes[0];
1440 /* make sure we can use eb after releasing the path */
1441 if (eb != eb_in) {
1442 if (!path->skip_locking)
1443 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1444 path->nodes[0] = NULL;
1445 path->locks[0] = 0;
1446 }
1447 btrfs_release_path(path);
1448 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1449
1450 name_len = btrfs_inode_ref_name_len(eb, iref);
1451 name_off = (unsigned long)(iref + 1);
1452
1453 parent = next_inum;
1454 --bytes_left;
1455 if (bytes_left >= 0)
1456 dest[bytes_left] = '/';
1457 }
1458
1459 btrfs_release_path(path);
1460 path->leave_spinning = leave_spinning;
1461
1462 if (ret)
1463 return ERR_PTR(ret);
1464
1465 return dest + bytes_left;
1466 }
1467
1468 /*
1469 * this makes the path point to (logical EXTENT_ITEM *)
1470 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1471 * tree blocks and <0 on error.
1472 */
1473 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1474 struct btrfs_path *path, struct btrfs_key *found_key,
1475 u64 *flags_ret)
1476 {
1477 int ret;
1478 u64 flags;
1479 u64 size = 0;
1480 u32 item_size;
1481 struct extent_buffer *eb;
1482 struct btrfs_extent_item *ei;
1483 struct btrfs_key key;
1484
1485 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1486 key.type = BTRFS_METADATA_ITEM_KEY;
1487 else
1488 key.type = BTRFS_EXTENT_ITEM_KEY;
1489 key.objectid = logical;
1490 key.offset = (u64)-1;
1491
1492 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1493 if (ret < 0)
1494 return ret;
1495
1496 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1497 if (ret) {
1498 if (ret > 0)
1499 ret = -ENOENT;
1500 return ret;
1501 }
1502 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1503 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1504 size = fs_info->extent_root->nodesize;
1505 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1506 size = found_key->offset;
1507
1508 if (found_key->objectid > logical ||
1509 found_key->objectid + size <= logical) {
1510 pr_debug("logical %llu is not within any extent\n", logical);
1511 return -ENOENT;
1512 }
1513
1514 eb = path->nodes[0];
1515 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1516 BUG_ON(item_size < sizeof(*ei));
1517
1518 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1519 flags = btrfs_extent_flags(eb, ei);
1520
1521 pr_debug("logical %llu is at position %llu within the extent (%llu "
1522 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1523 logical, logical - found_key->objectid, found_key->objectid,
1524 found_key->offset, flags, item_size);
1525
1526 WARN_ON(!flags_ret);
1527 if (flags_ret) {
1528 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1529 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1530 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1531 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1532 else
1533 BUG_ON(1);
1534 return 0;
1535 }
1536
1537 return -EIO;
1538 }
1539
1540 /*
1541 * helper function to iterate extent inline refs. ptr must point to a 0 value
1542 * for the first call and may be modified. it is used to track state.
1543 * if more refs exist, 0 is returned and the next call to
1544 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1545 * next ref. after the last ref was processed, 1 is returned.
1546 * returns <0 on error
1547 */
1548 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1549 struct btrfs_key *key,
1550 struct btrfs_extent_item *ei, u32 item_size,
1551 struct btrfs_extent_inline_ref **out_eiref,
1552 int *out_type)
1553 {
1554 unsigned long end;
1555 u64 flags;
1556 struct btrfs_tree_block_info *info;
1557
1558 if (!*ptr) {
1559 /* first call */
1560 flags = btrfs_extent_flags(eb, ei);
1561 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1562 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1563 /* a skinny metadata extent */
1564 *out_eiref =
1565 (struct btrfs_extent_inline_ref *)(ei + 1);
1566 } else {
1567 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1568 info = (struct btrfs_tree_block_info *)(ei + 1);
1569 *out_eiref =
1570 (struct btrfs_extent_inline_ref *)(info + 1);
1571 }
1572 } else {
1573 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1574 }
1575 *ptr = (unsigned long)*out_eiref;
1576 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1577 return -ENOENT;
1578 }
1579
1580 end = (unsigned long)ei + item_size;
1581 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1582 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1583
1584 *ptr += btrfs_extent_inline_ref_size(*out_type);
1585 WARN_ON(*ptr > end);
1586 if (*ptr == end)
1587 return 1; /* last */
1588
1589 return 0;
1590 }
1591
1592 /*
1593 * reads the tree block backref for an extent. tree level and root are returned
1594 * through out_level and out_root. ptr must point to a 0 value for the first
1595 * call and may be modified (see __get_extent_inline_ref comment).
1596 * returns 0 if data was provided, 1 if there was no more data to provide or
1597 * <0 on error.
1598 */
1599 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1600 struct btrfs_key *key, struct btrfs_extent_item *ei,
1601 u32 item_size, u64 *out_root, u8 *out_level)
1602 {
1603 int ret;
1604 int type;
1605 struct btrfs_extent_inline_ref *eiref;
1606
1607 if (*ptr == (unsigned long)-1)
1608 return 1;
1609
1610 while (1) {
1611 ret = __get_extent_inline_ref(ptr, eb, key, ei, item_size,
1612 &eiref, &type);
1613 if (ret < 0)
1614 return ret;
1615
1616 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1617 type == BTRFS_SHARED_BLOCK_REF_KEY)
1618 break;
1619
1620 if (ret == 1)
1621 return 1;
1622 }
1623
1624 /* we can treat both ref types equally here */
1625 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1626
1627 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1628 struct btrfs_tree_block_info *info;
1629
1630 info = (struct btrfs_tree_block_info *)(ei + 1);
1631 *out_level = btrfs_tree_block_level(eb, info);
1632 } else {
1633 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1634 *out_level = (u8)key->offset;
1635 }
1636
1637 if (ret == 1)
1638 *ptr = (unsigned long)-1;
1639
1640 return 0;
1641 }
1642
1643 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1644 u64 root, u64 extent_item_objectid,
1645 iterate_extent_inodes_t *iterate, void *ctx)
1646 {
1647 struct extent_inode_elem *eie;
1648 int ret = 0;
1649
1650 for (eie = inode_list; eie; eie = eie->next) {
1651 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1652 "root %llu\n", extent_item_objectid,
1653 eie->inum, eie->offset, root);
1654 ret = iterate(eie->inum, eie->offset, root, ctx);
1655 if (ret) {
1656 pr_debug("stopping iteration for %llu due to ret=%d\n",
1657 extent_item_objectid, ret);
1658 break;
1659 }
1660 }
1661
1662 return ret;
1663 }
1664
1665 /*
1666 * calls iterate() for every inode that references the extent identified by
1667 * the given parameters.
1668 * when the iterator function returns a non-zero value, iteration stops.
1669 */
1670 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1671 u64 extent_item_objectid, u64 extent_item_pos,
1672 int search_commit_root,
1673 iterate_extent_inodes_t *iterate, void *ctx)
1674 {
1675 int ret;
1676 struct btrfs_trans_handle *trans = NULL;
1677 struct ulist *refs = NULL;
1678 struct ulist *roots = NULL;
1679 struct ulist_node *ref_node = NULL;
1680 struct ulist_node *root_node = NULL;
1681 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
1682 struct ulist_iterator ref_uiter;
1683 struct ulist_iterator root_uiter;
1684
1685 pr_debug("resolving all inodes for extent %llu\n",
1686 extent_item_objectid);
1687
1688 if (!search_commit_root) {
1689 trans = btrfs_attach_transaction(fs_info->extent_root);
1690 if (IS_ERR(trans)) {
1691 if (PTR_ERR(trans) != -ENOENT &&
1692 PTR_ERR(trans) != -EROFS)
1693 return PTR_ERR(trans);
1694 trans = NULL;
1695 }
1696 }
1697
1698 if (trans)
1699 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1700 else
1701 down_read(&fs_info->commit_root_sem);
1702
1703 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1704 tree_mod_seq_elem.seq, &refs,
1705 &extent_item_pos);
1706 if (ret)
1707 goto out;
1708
1709 ULIST_ITER_INIT(&ref_uiter);
1710 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1711 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
1712 tree_mod_seq_elem.seq, &roots);
1713 if (ret)
1714 break;
1715 ULIST_ITER_INIT(&root_uiter);
1716 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1717 pr_debug("root %llu references leaf %llu, data list "
1718 "%#llx\n", root_node->val, ref_node->val,
1719 ref_node->aux);
1720 ret = iterate_leaf_refs((struct extent_inode_elem *)
1721 (uintptr_t)ref_node->aux,
1722 root_node->val,
1723 extent_item_objectid,
1724 iterate, ctx);
1725 }
1726 ulist_free(roots);
1727 }
1728
1729 free_leaf_list(refs);
1730 out:
1731 if (trans) {
1732 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1733 btrfs_end_transaction(trans, fs_info->extent_root);
1734 } else {
1735 up_read(&fs_info->commit_root_sem);
1736 }
1737
1738 return ret;
1739 }
1740
1741 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1742 struct btrfs_path *path,
1743 iterate_extent_inodes_t *iterate, void *ctx)
1744 {
1745 int ret;
1746 u64 extent_item_pos;
1747 u64 flags = 0;
1748 struct btrfs_key found_key;
1749 int search_commit_root = path->search_commit_root;
1750
1751 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1752 btrfs_release_path(path);
1753 if (ret < 0)
1754 return ret;
1755 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1756 return -EINVAL;
1757
1758 extent_item_pos = logical - found_key.objectid;
1759 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1760 extent_item_pos, search_commit_root,
1761 iterate, ctx);
1762
1763 return ret;
1764 }
1765
1766 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1767 struct extent_buffer *eb, void *ctx);
1768
1769 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1770 struct btrfs_path *path,
1771 iterate_irefs_t *iterate, void *ctx)
1772 {
1773 int ret = 0;
1774 int slot;
1775 u32 cur;
1776 u32 len;
1777 u32 name_len;
1778 u64 parent = 0;
1779 int found = 0;
1780 struct extent_buffer *eb;
1781 struct btrfs_item *item;
1782 struct btrfs_inode_ref *iref;
1783 struct btrfs_key found_key;
1784
1785 while (!ret) {
1786 ret = btrfs_find_item(fs_root, path, inum,
1787 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
1788 &found_key);
1789
1790 if (ret < 0)
1791 break;
1792 if (ret) {
1793 ret = found ? 0 : -ENOENT;
1794 break;
1795 }
1796 ++found;
1797
1798 parent = found_key.offset;
1799 slot = path->slots[0];
1800 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1801 if (!eb) {
1802 ret = -ENOMEM;
1803 break;
1804 }
1805 extent_buffer_get(eb);
1806 btrfs_tree_read_lock(eb);
1807 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1808 btrfs_release_path(path);
1809
1810 item = btrfs_item_nr(slot);
1811 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1812
1813 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1814 name_len = btrfs_inode_ref_name_len(eb, iref);
1815 /* path must be released before calling iterate()! */
1816 pr_debug("following ref at offset %u for inode %llu in "
1817 "tree %llu\n", cur, found_key.objectid,
1818 fs_root->objectid);
1819 ret = iterate(parent, name_len,
1820 (unsigned long)(iref + 1), eb, ctx);
1821 if (ret)
1822 break;
1823 len = sizeof(*iref) + name_len;
1824 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1825 }
1826 btrfs_tree_read_unlock_blocking(eb);
1827 free_extent_buffer(eb);
1828 }
1829
1830 btrfs_release_path(path);
1831
1832 return ret;
1833 }
1834
1835 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1836 struct btrfs_path *path,
1837 iterate_irefs_t *iterate, void *ctx)
1838 {
1839 int ret;
1840 int slot;
1841 u64 offset = 0;
1842 u64 parent;
1843 int found = 0;
1844 struct extent_buffer *eb;
1845 struct btrfs_inode_extref *extref;
1846 u32 item_size;
1847 u32 cur_offset;
1848 unsigned long ptr;
1849
1850 while (1) {
1851 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1852 &offset);
1853 if (ret < 0)
1854 break;
1855 if (ret) {
1856 ret = found ? 0 : -ENOENT;
1857 break;
1858 }
1859 ++found;
1860
1861 slot = path->slots[0];
1862 eb = btrfs_clone_extent_buffer(path->nodes[0]);
1863 if (!eb) {
1864 ret = -ENOMEM;
1865 break;
1866 }
1867 extent_buffer_get(eb);
1868
1869 btrfs_tree_read_lock(eb);
1870 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1871 btrfs_release_path(path);
1872
1873 item_size = btrfs_item_size_nr(eb, slot);
1874 ptr = btrfs_item_ptr_offset(eb, slot);
1875 cur_offset = 0;
1876
1877 while (cur_offset < item_size) {
1878 u32 name_len;
1879
1880 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1881 parent = btrfs_inode_extref_parent(eb, extref);
1882 name_len = btrfs_inode_extref_name_len(eb, extref);
1883 ret = iterate(parent, name_len,
1884 (unsigned long)&extref->name, eb, ctx);
1885 if (ret)
1886 break;
1887
1888 cur_offset += btrfs_inode_extref_name_len(eb, extref);
1889 cur_offset += sizeof(*extref);
1890 }
1891 btrfs_tree_read_unlock_blocking(eb);
1892 free_extent_buffer(eb);
1893
1894 offset++;
1895 }
1896
1897 btrfs_release_path(path);
1898
1899 return ret;
1900 }
1901
1902 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1903 struct btrfs_path *path, iterate_irefs_t *iterate,
1904 void *ctx)
1905 {
1906 int ret;
1907 int found_refs = 0;
1908
1909 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1910 if (!ret)
1911 ++found_refs;
1912 else if (ret != -ENOENT)
1913 return ret;
1914
1915 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1916 if (ret == -ENOENT && found_refs)
1917 return 0;
1918
1919 return ret;
1920 }
1921
1922 /*
1923 * returns 0 if the path could be dumped (probably truncated)
1924 * returns <0 in case of an error
1925 */
1926 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1927 struct extent_buffer *eb, void *ctx)
1928 {
1929 struct inode_fs_paths *ipath = ctx;
1930 char *fspath;
1931 char *fspath_min;
1932 int i = ipath->fspath->elem_cnt;
1933 const int s_ptr = sizeof(char *);
1934 u32 bytes_left;
1935
1936 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1937 ipath->fspath->bytes_left - s_ptr : 0;
1938
1939 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1940 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1941 name_off, eb, inum, fspath_min, bytes_left);
1942 if (IS_ERR(fspath))
1943 return PTR_ERR(fspath);
1944
1945 if (fspath > fspath_min) {
1946 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1947 ++ipath->fspath->elem_cnt;
1948 ipath->fspath->bytes_left = fspath - fspath_min;
1949 } else {
1950 ++ipath->fspath->elem_missed;
1951 ipath->fspath->bytes_missing += fspath_min - fspath;
1952 ipath->fspath->bytes_left = 0;
1953 }
1954
1955 return 0;
1956 }
1957
1958 /*
1959 * this dumps all file system paths to the inode into the ipath struct, provided
1960 * is has been created large enough. each path is zero-terminated and accessed
1961 * from ipath->fspath->val[i].
1962 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1963 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1964 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1965 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1966 * have been needed to return all paths.
1967 */
1968 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1969 {
1970 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1971 inode_to_path, ipath);
1972 }
1973
1974 struct btrfs_data_container *init_data_container(u32 total_bytes)
1975 {
1976 struct btrfs_data_container *data;
1977 size_t alloc_bytes;
1978
1979 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1980 data = vmalloc(alloc_bytes);
1981 if (!data)
1982 return ERR_PTR(-ENOMEM);
1983
1984 if (total_bytes >= sizeof(*data)) {
1985 data->bytes_left = total_bytes - sizeof(*data);
1986 data->bytes_missing = 0;
1987 } else {
1988 data->bytes_missing = sizeof(*data) - total_bytes;
1989 data->bytes_left = 0;
1990 }
1991
1992 data->elem_cnt = 0;
1993 data->elem_missed = 0;
1994
1995 return data;
1996 }
1997
1998 /*
1999 * allocates space to return multiple file system paths for an inode.
2000 * total_bytes to allocate are passed, note that space usable for actual path
2001 * information will be total_bytes - sizeof(struct inode_fs_paths).
2002 * the returned pointer must be freed with free_ipath() in the end.
2003 */
2004 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2005 struct btrfs_path *path)
2006 {
2007 struct inode_fs_paths *ifp;
2008 struct btrfs_data_container *fspath;
2009
2010 fspath = init_data_container(total_bytes);
2011 if (IS_ERR(fspath))
2012 return (void *)fspath;
2013
2014 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
2015 if (!ifp) {
2016 kfree(fspath);
2017 return ERR_PTR(-ENOMEM);
2018 }
2019
2020 ifp->btrfs_path = path;
2021 ifp->fspath = fspath;
2022 ifp->fs_root = fs_root;
2023
2024 return ifp;
2025 }
2026
2027 void free_ipath(struct inode_fs_paths *ipath)
2028 {
2029 if (!ipath)
2030 return;
2031 vfree(ipath->fspath);
2032 kfree(ipath);
2033 }
Linux with added FPC-III support