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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2011 STRATO. All rights reserved.
4 */
5
6#include <linux/mm.h>
7#include <linux/rbtree.h>
8#include <trace/events/btrfs.h>
9#include "ctree.h"
10#include "disk-io.h"
11#include "backref.h"
12#include "ulist.h"
13#include "transaction.h"
14#include "delayed-ref.h"
15#include "locking.h"
16
17/* Just an arbitrary number so we can be sure this happened */
18#define BACKREF_FOUND_SHARED 6
19
20struct extent_inode_elem {
21 u64 inum;
22 u64 offset;
23 struct extent_inode_elem *next;
24};
25
26static int check_extent_in_eb(const struct btrfs_key *key,
27 const struct extent_buffer *eb,
28 const struct btrfs_file_extent_item *fi,
29 u64 extent_item_pos,
30 struct extent_inode_elem **eie,
31 bool ignore_offset)
32{
33 u64 offset = 0;
34 struct extent_inode_elem *e;
35
36 if (!ignore_offset &&
37 !btrfs_file_extent_compression(eb, fi) &&
38 !btrfs_file_extent_encryption(eb, fi) &&
39 !btrfs_file_extent_other_encoding(eb, fi)) {
40 u64 data_offset;
41 u64 data_len;
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 offset = extent_item_pos - data_offset;
50 }
51
52 e = kmalloc(sizeof(*e), GFP_NOFS);
53 if (!e)
54 return -ENOMEM;
55
56 e->next = *eie;
57 e->inum = key->objectid;
58 e->offset = key->offset + offset;
59 *eie = e;
60
61 return 0;
62}
63
64static void free_inode_elem_list(struct extent_inode_elem *eie)
65{
66 struct extent_inode_elem *eie_next;
67
68 for (; eie; eie = eie_next) {
69 eie_next = eie->next;
70 kfree(eie);
71 }
72}
73
74static int find_extent_in_eb(const struct extent_buffer *eb,
75 u64 wanted_disk_byte, u64 extent_item_pos,
76 struct extent_inode_elem **eie,
77 bool ignore_offset)
78{
79 u64 disk_byte;
80 struct btrfs_key key;
81 struct btrfs_file_extent_item *fi;
82 int slot;
83 int nritems;
84 int extent_type;
85 int ret;
86
87 /*
88 * from the shared data ref, we only have the leaf but we need
89 * the key. thus, we must look into all items and see that we
90 * find one (some) with a reference to our extent item.
91 */
92 nritems = btrfs_header_nritems(eb);
93 for (slot = 0; slot < nritems; ++slot) {
94 btrfs_item_key_to_cpu(eb, &key, slot);
95 if (key.type != BTRFS_EXTENT_DATA_KEY)
96 continue;
97 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
98 extent_type = btrfs_file_extent_type(eb, fi);
99 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
100 continue;
101 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
102 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
103 if (disk_byte != wanted_disk_byte)
104 continue;
105
106 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie, ignore_offset);
107 if (ret < 0)
108 return ret;
109 }
110
111 return 0;
112}
113
114struct preftree {
115 struct rb_root root;
116 unsigned int count;
117};
118
119#define PREFTREE_INIT { .root = RB_ROOT, .count = 0 }
120
121struct preftrees {
122 struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */
123 struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */
124 struct preftree indirect_missing_keys;
125};
126
127/*
128 * Checks for a shared extent during backref search.
129 *
130 * The share_count tracks prelim_refs (direct and indirect) having a
131 * ref->count >0:
132 * - incremented when a ref->count transitions to >0
133 * - decremented when a ref->count transitions to <1
134 */
135struct share_check {
136 u64 root_objectid;
137 u64 inum;
138 int share_count;
139};
140
141static inline int extent_is_shared(struct share_check *sc)
142{
143 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
144}
145
146static struct kmem_cache *btrfs_prelim_ref_cache;
147
148int __init btrfs_prelim_ref_init(void)
149{
150 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
151 sizeof(struct prelim_ref),
152 0,
153 SLAB_MEM_SPREAD,
154 NULL);
155 if (!btrfs_prelim_ref_cache)
156 return -ENOMEM;
157 return 0;
158}
159
160void __cold btrfs_prelim_ref_exit(void)
161{
162 kmem_cache_destroy(btrfs_prelim_ref_cache);
163}
164
165static void free_pref(struct prelim_ref *ref)
166{
167 kmem_cache_free(btrfs_prelim_ref_cache, ref);
168}
169
170/*
171 * Return 0 when both refs are for the same block (and can be merged).
172 * A -1 return indicates ref1 is a 'lower' block than ref2, while 1
173 * indicates a 'higher' block.
174 */
175static int prelim_ref_compare(struct prelim_ref *ref1,
176 struct prelim_ref *ref2)
177{
178 if (ref1->level < ref2->level)
179 return -1;
180 if (ref1->level > ref2->level)
181 return 1;
182 if (ref1->root_id < ref2->root_id)
183 return -1;
184 if (ref1->root_id > ref2->root_id)
185 return 1;
186 if (ref1->key_for_search.type < ref2->key_for_search.type)
187 return -1;
188 if (ref1->key_for_search.type > ref2->key_for_search.type)
189 return 1;
190 if (ref1->key_for_search.objectid < ref2->key_for_search.objectid)
191 return -1;
192 if (ref1->key_for_search.objectid > ref2->key_for_search.objectid)
193 return 1;
194 if (ref1->key_for_search.offset < ref2->key_for_search.offset)
195 return -1;
196 if (ref1->key_for_search.offset > ref2->key_for_search.offset)
197 return 1;
198 if (ref1->parent < ref2->parent)
199 return -1;
200 if (ref1->parent > ref2->parent)
201 return 1;
202
203 return 0;
204}
205
206static void update_share_count(struct share_check *sc, int oldcount,
207 int newcount)
208{
209 if ((!sc) || (oldcount == 0 && newcount < 1))
210 return;
211
212 if (oldcount > 0 && newcount < 1)
213 sc->share_count--;
214 else if (oldcount < 1 && newcount > 0)
215 sc->share_count++;
216}
217
218/*
219 * Add @newref to the @root rbtree, merging identical refs.
220 *
221 * Callers should assume that newref has been freed after calling.
222 */
223static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
224 struct preftree *preftree,
225 struct prelim_ref *newref,
226 struct share_check *sc)
227{
228 struct rb_root *root;
229 struct rb_node **p;
230 struct rb_node *parent = NULL;
231 struct prelim_ref *ref;
232 int result;
233
234 root = &preftree->root;
235 p = &root->rb_node;
236
237 while (*p) {
238 parent = *p;
239 ref = rb_entry(parent, struct prelim_ref, rbnode);
240 result = prelim_ref_compare(ref, newref);
241 if (result < 0) {
242 p = &(*p)->rb_left;
243 } else if (result > 0) {
244 p = &(*p)->rb_right;
245 } else {
246 /* Identical refs, merge them and free @newref */
247 struct extent_inode_elem *eie = ref->inode_list;
248
249 while (eie && eie->next)
250 eie = eie->next;
251
252 if (!eie)
253 ref->inode_list = newref->inode_list;
254 else
255 eie->next = newref->inode_list;
256 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
257 preftree->count);
258 /*
259 * A delayed ref can have newref->count < 0.
260 * The ref->count is updated to follow any
261 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
262 */
263 update_share_count(sc, ref->count,
264 ref->count + newref->count);
265 ref->count += newref->count;
266 free_pref(newref);
267 return;
268 }
269 }
270
271 update_share_count(sc, 0, newref->count);
272 preftree->count++;
273 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
274 rb_link_node(&newref->rbnode, parent, p);
275 rb_insert_color(&newref->rbnode, root);
276}
277
278/*
279 * Release the entire tree. We don't care about internal consistency so
280 * just free everything and then reset the tree root.
281 */
282static void prelim_release(struct preftree *preftree)
283{
284 struct prelim_ref *ref, *next_ref;
285
286 rbtree_postorder_for_each_entry_safe(ref, next_ref, &preftree->root,
287 rbnode)
288 free_pref(ref);
289
290 preftree->root = RB_ROOT;
291 preftree->count = 0;
292}
293
294/*
295 * the rules for all callers of this function are:
296 * - obtaining the parent is the goal
297 * - if you add a key, you must know that it is a correct key
298 * - if you cannot add the parent or a correct key, then we will look into the
299 * block later to set a correct key
300 *
301 * delayed refs
302 * ============
303 * backref type | shared | indirect | shared | indirect
304 * information | tree | tree | data | data
305 * --------------------+--------+----------+--------+----------
306 * parent logical | y | - | - | -
307 * key to resolve | - | y | y | y
308 * tree block logical | - | - | - | -
309 * root for resolving | y | y | y | y
310 *
311 * - column 1: we've the parent -> done
312 * - column 2, 3, 4: we use the key to find the parent
313 *
314 * on disk refs (inline or keyed)
315 * ==============================
316 * backref type | shared | indirect | shared | indirect
317 * information | tree | tree | data | data
318 * --------------------+--------+----------+--------+----------
319 * parent logical | y | - | y | -
320 * key to resolve | - | - | - | y
321 * tree block logical | y | y | y | y
322 * root for resolving | - | y | y | y
323 *
324 * - column 1, 3: we've the parent -> done
325 * - column 2: we take the first key from the block to find the parent
326 * (see add_missing_keys)
327 * - column 4: we use the key to find the parent
328 *
329 * additional information that's available but not required to find the parent
330 * block might help in merging entries to gain some speed.
331 */
332static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
333 struct preftree *preftree, u64 root_id,
334 const struct btrfs_key *key, int level, u64 parent,
335 u64 wanted_disk_byte, int count,
336 struct share_check *sc, gfp_t gfp_mask)
337{
338 struct prelim_ref *ref;
339
340 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
341 return 0;
342
343 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
344 if (!ref)
345 return -ENOMEM;
346
347 ref->root_id = root_id;
348 if (key) {
349 ref->key_for_search = *key;
350 /*
351 * We can often find data backrefs with an offset that is too
352 * large (>= LLONG_MAX, maximum allowed file offset) due to
353 * underflows when subtracting a file's offset with the data
354 * offset of its corresponding extent data item. This can
355 * happen for example in the clone ioctl.
356 * So if we detect such case we set the search key's offset to
357 * zero to make sure we will find the matching file extent item
358 * at add_all_parents(), otherwise we will miss it because the
359 * offset taken form the backref is much larger then the offset
360 * of the file extent item. This can make us scan a very large
361 * number of file extent items, but at least it will not make
362 * us miss any.
363 * This is an ugly workaround for a behaviour that should have
364 * never existed, but it does and a fix for the clone ioctl
365 * would touch a lot of places, cause backwards incompatibility
366 * and would not fix the problem for extents cloned with older
367 * kernels.
368 */
369 if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY &&
370 ref->key_for_search.offset >= LLONG_MAX)
371 ref->key_for_search.offset = 0;
372 } else {
373 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
374 }
375
376 ref->inode_list = NULL;
377 ref->level = level;
378 ref->count = count;
379 ref->parent = parent;
380 ref->wanted_disk_byte = wanted_disk_byte;
381 prelim_ref_insert(fs_info, preftree, ref, sc);
382 return extent_is_shared(sc);
383}
384
385/* direct refs use root == 0, key == NULL */
386static int add_direct_ref(const struct btrfs_fs_info *fs_info,
387 struct preftrees *preftrees, int level, u64 parent,
388 u64 wanted_disk_byte, int count,
389 struct share_check *sc, gfp_t gfp_mask)
390{
391 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
392 parent, wanted_disk_byte, count, sc, gfp_mask);
393}
394
395/* indirect refs use parent == 0 */
396static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
397 struct preftrees *preftrees, u64 root_id,
398 const struct btrfs_key *key, int level,
399 u64 wanted_disk_byte, int count,
400 struct share_check *sc, gfp_t gfp_mask)
401{
402 struct preftree *tree = &preftrees->indirect;
403
404 if (!key)
405 tree = &preftrees->indirect_missing_keys;
406 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
407 wanted_disk_byte, count, sc, gfp_mask);
408}
409
410static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
411 struct ulist *parents, struct prelim_ref *ref,
412 int level, u64 time_seq, const u64 *extent_item_pos,
413 u64 total_refs, bool ignore_offset)
414{
415 int ret = 0;
416 int slot;
417 struct extent_buffer *eb;
418 struct btrfs_key key;
419 struct btrfs_key *key_for_search = &ref->key_for_search;
420 struct btrfs_file_extent_item *fi;
421 struct extent_inode_elem *eie = NULL, *old = NULL;
422 u64 disk_byte;
423 u64 wanted_disk_byte = ref->wanted_disk_byte;
424 u64 count = 0;
425
426 if (level != 0) {
427 eb = path->nodes[level];
428 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
429 if (ret < 0)
430 return ret;
431 return 0;
432 }
433
434 /*
435 * We normally enter this function with the path already pointing to
436 * the first item to check. But sometimes, we may enter it with
437 * slot==nritems. In that case, go to the next leaf before we continue.
438 */
439 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
440 if (time_seq == SEQ_LAST)
441 ret = btrfs_next_leaf(root, path);
442 else
443 ret = btrfs_next_old_leaf(root, path, time_seq);
444 }
445
446 while (!ret && count < total_refs) {
447 eb = path->nodes[0];
448 slot = path->slots[0];
449
450 btrfs_item_key_to_cpu(eb, &key, slot);
451
452 if (key.objectid != key_for_search->objectid ||
453 key.type != BTRFS_EXTENT_DATA_KEY)
454 break;
455
456 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
457 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
458
459 if (disk_byte == wanted_disk_byte) {
460 eie = NULL;
461 old = NULL;
462 count++;
463 if (extent_item_pos) {
464 ret = check_extent_in_eb(&key, eb, fi,
465 *extent_item_pos,
466 &eie, ignore_offset);
467 if (ret < 0)
468 break;
469 }
470 if (ret > 0)
471 goto next;
472 ret = ulist_add_merge_ptr(parents, eb->start,
473 eie, (void **)&old, GFP_NOFS);
474 if (ret < 0)
475 break;
476 if (!ret && extent_item_pos) {
477 while (old->next)
478 old = old->next;
479 old->next = eie;
480 }
481 eie = NULL;
482 }
483next:
484 if (time_seq == SEQ_LAST)
485 ret = btrfs_next_item(root, path);
486 else
487 ret = btrfs_next_old_item(root, path, time_seq);
488 }
489
490 if (ret > 0)
491 ret = 0;
492 else if (ret < 0)
493 free_inode_elem_list(eie);
494 return ret;
495}
496
497/*
498 * resolve an indirect backref in the form (root_id, key, level)
499 * to a logical address
500 */
501static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
502 struct btrfs_path *path, u64 time_seq,
503 struct prelim_ref *ref, struct ulist *parents,
504 const u64 *extent_item_pos, u64 total_refs,
505 bool ignore_offset)
506{
507 struct btrfs_root *root;
508 struct btrfs_key root_key;
509 struct extent_buffer *eb;
510 int ret = 0;
511 int root_level;
512 int level = ref->level;
513 int index;
514
515 root_key.objectid = ref->root_id;
516 root_key.type = BTRFS_ROOT_ITEM_KEY;
517 root_key.offset = (u64)-1;
518
519 index = srcu_read_lock(&fs_info->subvol_srcu);
520
521 root = btrfs_get_fs_root(fs_info, &root_key, false);
522 if (IS_ERR(root)) {
523 srcu_read_unlock(&fs_info->subvol_srcu, index);
524 ret = PTR_ERR(root);
525 goto out;
526 }
527
528 if (btrfs_is_testing(fs_info)) {
529 srcu_read_unlock(&fs_info->subvol_srcu, index);
530 ret = -ENOENT;
531 goto out;
532 }
533
534 if (path->search_commit_root)
535 root_level = btrfs_header_level(root->commit_root);
536 else if (time_seq == SEQ_LAST)
537 root_level = btrfs_header_level(root->node);
538 else
539 root_level = btrfs_old_root_level(root, time_seq);
540
541 if (root_level + 1 == level) {
542 srcu_read_unlock(&fs_info->subvol_srcu, index);
543 goto out;
544 }
545
546 path->lowest_level = level;
547 if (time_seq == SEQ_LAST)
548 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path,
549 0, 0);
550 else
551 ret = btrfs_search_old_slot(root, &ref->key_for_search, path,
552 time_seq);
553
554 /* root node has been locked, we can release @subvol_srcu safely here */
555 srcu_read_unlock(&fs_info->subvol_srcu, index);
556
557 btrfs_debug(fs_info,
558 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
559 ref->root_id, level, ref->count, ret,
560 ref->key_for_search.objectid, ref->key_for_search.type,
561 ref->key_for_search.offset);
562 if (ret < 0)
563 goto out;
564
565 eb = path->nodes[level];
566 while (!eb) {
567 if (WARN_ON(!level)) {
568 ret = 1;
569 goto out;
570 }
571 level--;
572 eb = path->nodes[level];
573 }
574
575 ret = add_all_parents(root, path, parents, ref, level, time_seq,
576 extent_item_pos, total_refs, ignore_offset);
577out:
578 path->lowest_level = 0;
579 btrfs_release_path(path);
580 return ret;
581}
582
583static struct extent_inode_elem *
584unode_aux_to_inode_list(struct ulist_node *node)
585{
586 if (!node)
587 return NULL;
588 return (struct extent_inode_elem *)(uintptr_t)node->aux;
589}
590
591/*
592 * We maintain three seperate rbtrees: one for direct refs, one for
593 * indirect refs which have a key, and one for indirect refs which do not
594 * have a key. Each tree does merge on insertion.
595 *
596 * Once all of the references are located, we iterate over the tree of
597 * indirect refs with missing keys. An appropriate key is located and
598 * the ref is moved onto the tree for indirect refs. After all missing
599 * keys are thus located, we iterate over the indirect ref tree, resolve
600 * each reference, and then insert the resolved reference onto the
601 * direct tree (merging there too).
602 *
603 * New backrefs (i.e., for parent nodes) are added to the appropriate
604 * rbtree as they are encountered. The new backrefs are subsequently
605 * resolved as above.
606 */
607static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
608 struct btrfs_path *path, u64 time_seq,
609 struct preftrees *preftrees,
610 const u64 *extent_item_pos, u64 total_refs,
611 struct share_check *sc, bool ignore_offset)
612{
613 int err;
614 int ret = 0;
615 struct ulist *parents;
616 struct ulist_node *node;
617 struct ulist_iterator uiter;
618 struct rb_node *rnode;
619
620 parents = ulist_alloc(GFP_NOFS);
621 if (!parents)
622 return -ENOMEM;
623
624 /*
625 * We could trade memory usage for performance here by iterating
626 * the tree, allocating new refs for each insertion, and then
627 * freeing the entire indirect tree when we're done. In some test
628 * cases, the tree can grow quite large (~200k objects).
629 */
630 while ((rnode = rb_first(&preftrees->indirect.root))) {
631 struct prelim_ref *ref;
632
633 ref = rb_entry(rnode, struct prelim_ref, rbnode);
634 if (WARN(ref->parent,
635 "BUG: direct ref found in indirect tree")) {
636 ret = -EINVAL;
637 goto out;
638 }
639
640 rb_erase(&ref->rbnode, &preftrees->indirect.root);
641 preftrees->indirect.count--;
642
643 if (ref->count == 0) {
644 free_pref(ref);
645 continue;
646 }
647
648 if (sc && sc->root_objectid &&
649 ref->root_id != sc->root_objectid) {
650 free_pref(ref);
651 ret = BACKREF_FOUND_SHARED;
652 goto out;
653 }
654 err = resolve_indirect_ref(fs_info, path, time_seq, ref,
655 parents, extent_item_pos,
656 total_refs, ignore_offset);
657 /*
658 * we can only tolerate ENOENT,otherwise,we should catch error
659 * and return directly.
660 */
661 if (err == -ENOENT) {
662 prelim_ref_insert(fs_info, &preftrees->direct, ref,
663 NULL);
664 continue;
665 } else if (err) {
666 free_pref(ref);
667 ret = err;
668 goto out;
669 }
670
671 /* we put the first parent into the ref at hand */
672 ULIST_ITER_INIT(&uiter);
673 node = ulist_next(parents, &uiter);
674 ref->parent = node ? node->val : 0;
675 ref->inode_list = unode_aux_to_inode_list(node);
676
677 /* Add a prelim_ref(s) for any other parent(s). */
678 while ((node = ulist_next(parents, &uiter))) {
679 struct prelim_ref *new_ref;
680
681 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
682 GFP_NOFS);
683 if (!new_ref) {
684 free_pref(ref);
685 ret = -ENOMEM;
686 goto out;
687 }
688 memcpy(new_ref, ref, sizeof(*ref));
689 new_ref->parent = node->val;
690 new_ref->inode_list = unode_aux_to_inode_list(node);
691 prelim_ref_insert(fs_info, &preftrees->direct,
692 new_ref, NULL);
693 }
694
695 /*
696 * Now it's a direct ref, put it in the the direct tree. We must
697 * do this last because the ref could be merged/freed here.
698 */
699 prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL);
700
701 ulist_reinit(parents);
702 cond_resched();
703 }
704out:
705 ulist_free(parents);
706 return ret;
707}
708
709/*
710 * read tree blocks and add keys where required.
711 */
712static int add_missing_keys(struct btrfs_fs_info *fs_info,
713 struct preftrees *preftrees)
714{
715 struct prelim_ref *ref;
716 struct extent_buffer *eb;
717 struct preftree *tree = &preftrees->indirect_missing_keys;
718 struct rb_node *node;
719
720 while ((node = rb_first(&tree->root))) {
721 ref = rb_entry(node, struct prelim_ref, rbnode);
722 rb_erase(node, &tree->root);
723
724 BUG_ON(ref->parent); /* should not be a direct ref */
725 BUG_ON(ref->key_for_search.type);
726 BUG_ON(!ref->wanted_disk_byte);
727
728 eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0,
729 ref->level - 1, NULL);
730 if (IS_ERR(eb)) {
731 free_pref(ref);
732 return PTR_ERR(eb);
733 } else if (!extent_buffer_uptodate(eb)) {
734 free_pref(ref);
735 free_extent_buffer(eb);
736 return -EIO;
737 }
738 btrfs_tree_read_lock(eb);
739 if (btrfs_header_level(eb) == 0)
740 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
741 else
742 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
743 btrfs_tree_read_unlock(eb);
744 free_extent_buffer(eb);
745 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
746 cond_resched();
747 }
748 return 0;
749}
750
751/*
752 * add all currently queued delayed refs from this head whose seq nr is
753 * smaller or equal that seq to the list
754 */
755static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
756 struct btrfs_delayed_ref_head *head, u64 seq,
757 struct preftrees *preftrees, u64 *total_refs,
758 struct share_check *sc)
759{
760 struct btrfs_delayed_ref_node *node;
761 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
762 struct btrfs_key key;
763 struct btrfs_key tmp_op_key;
764 struct rb_node *n;
765 int count;
766 int ret = 0;
767
768 if (extent_op && extent_op->update_key)
769 btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
770
771 spin_lock(&head->lock);
772 for (n = rb_first(&head->ref_tree); n; n = rb_next(n)) {
773 node = rb_entry(n, struct btrfs_delayed_ref_node,
774 ref_node);
775 if (node->seq > seq)
776 continue;
777
778 switch (node->action) {
779 case BTRFS_ADD_DELAYED_EXTENT:
780 case BTRFS_UPDATE_DELAYED_HEAD:
781 WARN_ON(1);
782 continue;
783 case BTRFS_ADD_DELAYED_REF:
784 count = node->ref_mod;
785 break;
786 case BTRFS_DROP_DELAYED_REF:
787 count = node->ref_mod * -1;
788 break;
789 default:
790 BUG_ON(1);
791 }
792 *total_refs += count;
793 switch (node->type) {
794 case BTRFS_TREE_BLOCK_REF_KEY: {
795 /* NORMAL INDIRECT METADATA backref */
796 struct btrfs_delayed_tree_ref *ref;
797
798 ref = btrfs_delayed_node_to_tree_ref(node);
799 ret = add_indirect_ref(fs_info, preftrees, ref->root,
800 &tmp_op_key, ref->level + 1,
801 node->bytenr, count, sc,
802 GFP_ATOMIC);
803 break;
804 }
805 case BTRFS_SHARED_BLOCK_REF_KEY: {
806 /* SHARED DIRECT METADATA backref */
807 struct btrfs_delayed_tree_ref *ref;
808
809 ref = btrfs_delayed_node_to_tree_ref(node);
810
811 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
812 ref->parent, node->bytenr, count,
813 sc, GFP_ATOMIC);
814 break;
815 }
816 case BTRFS_EXTENT_DATA_REF_KEY: {
817 /* NORMAL INDIRECT DATA backref */
818 struct btrfs_delayed_data_ref *ref;
819 ref = btrfs_delayed_node_to_data_ref(node);
820
821 key.objectid = ref->objectid;
822 key.type = BTRFS_EXTENT_DATA_KEY;
823 key.offset = ref->offset;
824
825 /*
826 * Found a inum that doesn't match our known inum, we
827 * know it's shared.
828 */
829 if (sc && sc->inum && ref->objectid != sc->inum) {
830 ret = BACKREF_FOUND_SHARED;
831 goto out;
832 }
833
834 ret = add_indirect_ref(fs_info, preftrees, ref->root,
835 &key, 0, node->bytenr, count, sc,
836 GFP_ATOMIC);
837 break;
838 }
839 case BTRFS_SHARED_DATA_REF_KEY: {
840 /* SHARED DIRECT FULL backref */
841 struct btrfs_delayed_data_ref *ref;
842
843 ref = btrfs_delayed_node_to_data_ref(node);
844
845 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
846 node->bytenr, count, sc,
847 GFP_ATOMIC);
848 break;
849 }
850 default:
851 WARN_ON(1);
852 }
853 /*
854 * We must ignore BACKREF_FOUND_SHARED until all delayed
855 * refs have been checked.
856 */
857 if (ret && (ret != BACKREF_FOUND_SHARED))
858 break;
859 }
860 if (!ret)
861 ret = extent_is_shared(sc);
862out:
863 spin_unlock(&head->lock);
864 return ret;
865}
866
867/*
868 * add all inline backrefs for bytenr to the list
869 *
870 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
871 */
872static int add_inline_refs(const struct btrfs_fs_info *fs_info,
873 struct btrfs_path *path, u64 bytenr,
874 int *info_level, struct preftrees *preftrees,
875 u64 *total_refs, struct share_check *sc)
876{
877 int ret = 0;
878 int slot;
879 struct extent_buffer *leaf;
880 struct btrfs_key key;
881 struct btrfs_key found_key;
882 unsigned long ptr;
883 unsigned long end;
884 struct btrfs_extent_item *ei;
885 u64 flags;
886 u64 item_size;
887
888 /*
889 * enumerate all inline refs
890 */
891 leaf = path->nodes[0];
892 slot = path->slots[0];
893
894 item_size = btrfs_item_size_nr(leaf, slot);
895 BUG_ON(item_size < sizeof(*ei));
896
897 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
898 flags = btrfs_extent_flags(leaf, ei);
899 *total_refs += btrfs_extent_refs(leaf, ei);
900 btrfs_item_key_to_cpu(leaf, &found_key, slot);
901
902 ptr = (unsigned long)(ei + 1);
903 end = (unsigned long)ei + item_size;
904
905 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
906 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
907 struct btrfs_tree_block_info *info;
908
909 info = (struct btrfs_tree_block_info *)ptr;
910 *info_level = btrfs_tree_block_level(leaf, info);
911 ptr += sizeof(struct btrfs_tree_block_info);
912 BUG_ON(ptr > end);
913 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
914 *info_level = found_key.offset;
915 } else {
916 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
917 }
918
919 while (ptr < end) {
920 struct btrfs_extent_inline_ref *iref;
921 u64 offset;
922 int type;
923
924 iref = (struct btrfs_extent_inline_ref *)ptr;
925 type = btrfs_get_extent_inline_ref_type(leaf, iref,
926 BTRFS_REF_TYPE_ANY);
927 if (type == BTRFS_REF_TYPE_INVALID)
928 return -EINVAL;
929
930 offset = btrfs_extent_inline_ref_offset(leaf, iref);
931
932 switch (type) {
933 case BTRFS_SHARED_BLOCK_REF_KEY:
934 ret = add_direct_ref(fs_info, preftrees,
935 *info_level + 1, offset,
936 bytenr, 1, NULL, GFP_NOFS);
937 break;
938 case BTRFS_SHARED_DATA_REF_KEY: {
939 struct btrfs_shared_data_ref *sdref;
940 int count;
941
942 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
943 count = btrfs_shared_data_ref_count(leaf, sdref);
944
945 ret = add_direct_ref(fs_info, preftrees, 0, offset,
946 bytenr, count, sc, GFP_NOFS);
947 break;
948 }
949 case BTRFS_TREE_BLOCK_REF_KEY:
950 ret = add_indirect_ref(fs_info, preftrees, offset,
951 NULL, *info_level + 1,
952 bytenr, 1, NULL, GFP_NOFS);
953 break;
954 case BTRFS_EXTENT_DATA_REF_KEY: {
955 struct btrfs_extent_data_ref *dref;
956 int count;
957 u64 root;
958
959 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
960 count = btrfs_extent_data_ref_count(leaf, dref);
961 key.objectid = btrfs_extent_data_ref_objectid(leaf,
962 dref);
963 key.type = BTRFS_EXTENT_DATA_KEY;
964 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
965
966 if (sc && sc->inum && key.objectid != sc->inum) {
967 ret = BACKREF_FOUND_SHARED;
968 break;
969 }
970
971 root = btrfs_extent_data_ref_root(leaf, dref);
972
973 ret = add_indirect_ref(fs_info, preftrees, root,
974 &key, 0, bytenr, count,
975 sc, GFP_NOFS);
976 break;
977 }
978 default:
979 WARN_ON(1);
980 }
981 if (ret)
982 return ret;
983 ptr += btrfs_extent_inline_ref_size(type);
984 }
985
986 return 0;
987}
988
989/*
990 * add all non-inline backrefs for bytenr to the list
991 *
992 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
993 */
994static int add_keyed_refs(struct btrfs_fs_info *fs_info,
995 struct btrfs_path *path, u64 bytenr,
996 int info_level, struct preftrees *preftrees,
997 struct share_check *sc)
998{
999 struct btrfs_root *extent_root = fs_info->extent_root;
1000 int ret;
1001 int slot;
1002 struct extent_buffer *leaf;
1003 struct btrfs_key key;
1004
1005 while (1) {
1006 ret = btrfs_next_item(extent_root, path);
1007 if (ret < 0)
1008 break;
1009 if (ret) {
1010 ret = 0;
1011 break;
1012 }
1013
1014 slot = path->slots[0];
1015 leaf = path->nodes[0];
1016 btrfs_item_key_to_cpu(leaf, &key, slot);
1017
1018 if (key.objectid != bytenr)
1019 break;
1020 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1021 continue;
1022 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1023 break;
1024
1025 switch (key.type) {
1026 case BTRFS_SHARED_BLOCK_REF_KEY:
1027 /* SHARED DIRECT METADATA backref */
1028 ret = add_direct_ref(fs_info, preftrees,
1029 info_level + 1, key.offset,
1030 bytenr, 1, NULL, GFP_NOFS);
1031 break;
1032 case BTRFS_SHARED_DATA_REF_KEY: {
1033 /* SHARED DIRECT FULL backref */
1034 struct btrfs_shared_data_ref *sdref;
1035 int count;
1036
1037 sdref = btrfs_item_ptr(leaf, slot,
1038 struct btrfs_shared_data_ref);
1039 count = btrfs_shared_data_ref_count(leaf, sdref);
1040 ret = add_direct_ref(fs_info, preftrees, 0,
1041 key.offset, bytenr, count,
1042 sc, GFP_NOFS);
1043 break;
1044 }
1045 case BTRFS_TREE_BLOCK_REF_KEY:
1046 /* NORMAL INDIRECT METADATA backref */
1047 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1048 NULL, info_level + 1, bytenr,
1049 1, NULL, GFP_NOFS);
1050 break;
1051 case BTRFS_EXTENT_DATA_REF_KEY: {
1052 /* NORMAL INDIRECT DATA backref */
1053 struct btrfs_extent_data_ref *dref;
1054 int count;
1055 u64 root;
1056
1057 dref = btrfs_item_ptr(leaf, slot,
1058 struct btrfs_extent_data_ref);
1059 count = btrfs_extent_data_ref_count(leaf, dref);
1060 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1061 dref);
1062 key.type = BTRFS_EXTENT_DATA_KEY;
1063 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1064
1065 if (sc && sc->inum && key.objectid != sc->inum) {
1066 ret = BACKREF_FOUND_SHARED;
1067 break;
1068 }
1069
1070 root = btrfs_extent_data_ref_root(leaf, dref);
1071 ret = add_indirect_ref(fs_info, preftrees, root,
1072 &key, 0, bytenr, count,
1073 sc, GFP_NOFS);
1074 break;
1075 }
1076 default:
1077 WARN_ON(1);
1078 }
1079 if (ret)
1080 return ret;
1081
1082 }
1083
1084 return ret;
1085}
1086
1087/*
1088 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1089 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1090 * indirect refs to their parent bytenr.
1091 * When roots are found, they're added to the roots list
1092 *
1093 * If time_seq is set to SEQ_LAST, it will not search delayed_refs, and behave
1094 * much like trans == NULL case, the difference only lies in it will not
1095 * commit root.
1096 * The special case is for qgroup to search roots in commit_transaction().
1097 *
1098 * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a
1099 * shared extent is detected.
1100 *
1101 * Otherwise this returns 0 for success and <0 for an error.
1102 *
1103 * If ignore_offset is set to false, only extent refs whose offsets match
1104 * extent_item_pos are returned. If true, every extent ref is returned
1105 * and extent_item_pos is ignored.
1106 *
1107 * FIXME some caching might speed things up
1108 */
1109static int find_parent_nodes(struct btrfs_trans_handle *trans,
1110 struct btrfs_fs_info *fs_info, u64 bytenr,
1111 u64 time_seq, struct ulist *refs,
1112 struct ulist *roots, const u64 *extent_item_pos,
1113 struct share_check *sc, bool ignore_offset)
1114{
1115 struct btrfs_key key;
1116 struct btrfs_path *path;
1117 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1118 struct btrfs_delayed_ref_head *head;
1119 int info_level = 0;
1120 int ret;
1121 struct prelim_ref *ref;
1122 struct rb_node *node;
1123 struct extent_inode_elem *eie = NULL;
1124 /* total of both direct AND indirect refs! */
1125 u64 total_refs = 0;
1126 struct preftrees preftrees = {
1127 .direct = PREFTREE_INIT,
1128 .indirect = PREFTREE_INIT,
1129 .indirect_missing_keys = PREFTREE_INIT
1130 };
1131
1132 key.objectid = bytenr;
1133 key.offset = (u64)-1;
1134 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1135 key.type = BTRFS_METADATA_ITEM_KEY;
1136 else
1137 key.type = BTRFS_EXTENT_ITEM_KEY;
1138
1139 path = btrfs_alloc_path();
1140 if (!path)
1141 return -ENOMEM;
1142 if (!trans) {
1143 path->search_commit_root = 1;
1144 path->skip_locking = 1;
1145 }
1146
1147 if (time_seq == SEQ_LAST)
1148 path->skip_locking = 1;
1149
1150 /*
1151 * grab both a lock on the path and a lock on the delayed ref head.
1152 * We need both to get a consistent picture of how the refs look
1153 * at a specified point in time
1154 */
1155again:
1156 head = NULL;
1157
1158 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
1159 if (ret < 0)
1160 goto out;
1161 BUG_ON(ret == 0);
1162
1163#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1164 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1165 time_seq != SEQ_LAST) {
1166#else
1167 if (trans && time_seq != SEQ_LAST) {
1168#endif
1169 /*
1170 * look if there are updates for this ref queued and lock the
1171 * head
1172 */
1173 delayed_refs = &trans->transaction->delayed_refs;
1174 spin_lock(&delayed_refs->lock);
1175 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
1176 if (head) {
1177 if (!mutex_trylock(&head->mutex)) {
1178 refcount_inc(&head->refs);
1179 spin_unlock(&delayed_refs->lock);
1180
1181 btrfs_release_path(path);
1182
1183 /*
1184 * Mutex was contended, block until it's
1185 * released and try again
1186 */
1187 mutex_lock(&head->mutex);
1188 mutex_unlock(&head->mutex);
1189 btrfs_put_delayed_ref_head(head);
1190 goto again;
1191 }
1192 spin_unlock(&delayed_refs->lock);
1193 ret = add_delayed_refs(fs_info, head, time_seq,
1194 &preftrees, &total_refs, sc);
1195 mutex_unlock(&head->mutex);
1196 if (ret)
1197 goto out;
1198 } else {
1199 spin_unlock(&delayed_refs->lock);
1200 }
1201 }
1202
1203 if (path->slots[0]) {
1204 struct extent_buffer *leaf;
1205 int slot;
1206
1207 path->slots[0]--;
1208 leaf = path->nodes[0];
1209 slot = path->slots[0];
1210 btrfs_item_key_to_cpu(leaf, &key, slot);
1211 if (key.objectid == bytenr &&
1212 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1213 key.type == BTRFS_METADATA_ITEM_KEY)) {
1214 ret = add_inline_refs(fs_info, path, bytenr,
1215 &info_level, &preftrees,
1216 &total_refs, sc);
1217 if (ret)
1218 goto out;
1219 ret = add_keyed_refs(fs_info, path, bytenr, info_level,
1220 &preftrees, sc);
1221 if (ret)
1222 goto out;
1223 }
1224 }
1225
1226 btrfs_release_path(path);
1227
1228 ret = add_missing_keys(fs_info, &preftrees);
1229 if (ret)
1230 goto out;
1231
1232 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root));
1233
1234 ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees,
1235 extent_item_pos, total_refs, sc, ignore_offset);
1236 if (ret)
1237 goto out;
1238
1239 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root));
1240
1241 /*
1242 * This walks the tree of merged and resolved refs. Tree blocks are
1243 * read in as needed. Unique entries are added to the ulist, and
1244 * the list of found roots is updated.
1245 *
1246 * We release the entire tree in one go before returning.
1247 */
1248 node = rb_first(&preftrees.direct.root);
1249 while (node) {
1250 ref = rb_entry(node, struct prelim_ref, rbnode);
1251 node = rb_next(&ref->rbnode);
1252 /*
1253 * ref->count < 0 can happen here if there are delayed
1254 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1255 * prelim_ref_insert() relies on this when merging
1256 * identical refs to keep the overall count correct.
1257 * prelim_ref_insert() will merge only those refs
1258 * which compare identically. Any refs having
1259 * e.g. different offsets would not be merged,
1260 * and would retain their original ref->count < 0.
1261 */
1262 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1263 if (sc && sc->root_objectid &&
1264 ref->root_id != sc->root_objectid) {
1265 ret = BACKREF_FOUND_SHARED;
1266 goto out;
1267 }
1268
1269 /* no parent == root of tree */
1270 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1271 if (ret < 0)
1272 goto out;
1273 }
1274 if (ref->count && ref->parent) {
1275 if (extent_item_pos && !ref->inode_list &&
1276 ref->level == 0) {
1277 struct extent_buffer *eb;
1278
1279 eb = read_tree_block(fs_info, ref->parent, 0,
1280 ref->level, NULL);
1281 if (IS_ERR(eb)) {
1282 ret = PTR_ERR(eb);
1283 goto out;
1284 } else if (!extent_buffer_uptodate(eb)) {
1285 free_extent_buffer(eb);
1286 ret = -EIO;
1287 goto out;
1288 }
1289 btrfs_tree_read_lock(eb);
1290 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1291 ret = find_extent_in_eb(eb, bytenr,
1292 *extent_item_pos, &eie, ignore_offset);
1293 btrfs_tree_read_unlock_blocking(eb);
1294 free_extent_buffer(eb);
1295 if (ret < 0)
1296 goto out;
1297 ref->inode_list = eie;
1298 }
1299 ret = ulist_add_merge_ptr(refs, ref->parent,
1300 ref->inode_list,
1301 (void **)&eie, GFP_NOFS);
1302 if (ret < 0)
1303 goto out;
1304 if (!ret && extent_item_pos) {
1305 /*
1306 * we've recorded that parent, so we must extend
1307 * its inode list here
1308 */
1309 BUG_ON(!eie);
1310 while (eie->next)
1311 eie = eie->next;
1312 eie->next = ref->inode_list;
1313 }
1314 eie = NULL;
1315 }
1316 cond_resched();
1317 }
1318
1319out:
1320 btrfs_free_path(path);
1321
1322 prelim_release(&preftrees.direct);
1323 prelim_release(&preftrees.indirect);
1324 prelim_release(&preftrees.indirect_missing_keys);
1325
1326 if (ret < 0)
1327 free_inode_elem_list(eie);
1328 return ret;
1329}
1330
1331static void free_leaf_list(struct ulist *blocks)
1332{
1333 struct ulist_node *node = NULL;
1334 struct extent_inode_elem *eie;
1335 struct ulist_iterator uiter;
1336
1337 ULIST_ITER_INIT(&uiter);
1338 while ((node = ulist_next(blocks, &uiter))) {
1339 if (!node->aux)
1340 continue;
1341 eie = unode_aux_to_inode_list(node);
1342 free_inode_elem_list(eie);
1343 node->aux = 0;
1344 }
1345
1346 ulist_free(blocks);
1347}
1348
1349/*
1350 * Finds all leafs with a reference to the specified combination of bytenr and
1351 * offset. key_list_head will point to a list of corresponding keys (caller must
1352 * free each list element). The leafs will be stored in the leafs ulist, which
1353 * must be freed with ulist_free.
1354 *
1355 * returns 0 on success, <0 on error
1356 */
1357static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1358 struct btrfs_fs_info *fs_info, u64 bytenr,
1359 u64 time_seq, struct ulist **leafs,
1360 const u64 *extent_item_pos, bool ignore_offset)
1361{
1362 int ret;
1363
1364 *leafs = ulist_alloc(GFP_NOFS);
1365 if (!*leafs)
1366 return -ENOMEM;
1367
1368 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1369 *leafs, NULL, extent_item_pos, NULL, ignore_offset);
1370 if (ret < 0 && ret != -ENOENT) {
1371 free_leaf_list(*leafs);
1372 return ret;
1373 }
1374
1375 return 0;
1376}
1377
1378/*
1379 * walk all backrefs for a given extent to find all roots that reference this
1380 * extent. Walking a backref means finding all extents that reference this
1381 * extent and in turn walk the backrefs of those, too. Naturally this is a
1382 * recursive process, but here it is implemented in an iterative fashion: We
1383 * find all referencing extents for the extent in question and put them on a
1384 * list. In turn, we find all referencing extents for those, further appending
1385 * to the list. The way we iterate the list allows adding more elements after
1386 * the current while iterating. The process stops when we reach the end of the
1387 * list. Found roots are added to the roots list.
1388 *
1389 * returns 0 on success, < 0 on error.
1390 */
1391static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
1392 struct btrfs_fs_info *fs_info, u64 bytenr,
1393 u64 time_seq, struct ulist **roots,
1394 bool ignore_offset)
1395{
1396 struct ulist *tmp;
1397 struct ulist_node *node = NULL;
1398 struct ulist_iterator uiter;
1399 int ret;
1400
1401 tmp = ulist_alloc(GFP_NOFS);
1402 if (!tmp)
1403 return -ENOMEM;
1404 *roots = ulist_alloc(GFP_NOFS);
1405 if (!*roots) {
1406 ulist_free(tmp);
1407 return -ENOMEM;
1408 }
1409
1410 ULIST_ITER_INIT(&uiter);
1411 while (1) {
1412 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1413 tmp, *roots, NULL, NULL, ignore_offset);
1414 if (ret < 0 && ret != -ENOENT) {
1415 ulist_free(tmp);
1416 ulist_free(*roots);
1417 return ret;
1418 }
1419 node = ulist_next(tmp, &uiter);
1420 if (!node)
1421 break;
1422 bytenr = node->val;
1423 cond_resched();
1424 }
1425
1426 ulist_free(tmp);
1427 return 0;
1428}
1429
1430int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1431 struct btrfs_fs_info *fs_info, u64 bytenr,
1432 u64 time_seq, struct ulist **roots,
1433 bool ignore_offset)
1434{
1435 int ret;
1436
1437 if (!trans)
1438 down_read(&fs_info->commit_root_sem);
1439 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr,
1440 time_seq, roots, ignore_offset);
1441 if (!trans)
1442 up_read(&fs_info->commit_root_sem);
1443 return ret;
1444}
1445
1446/**
1447 * btrfs_check_shared - tell us whether an extent is shared
1448 *
1449 * btrfs_check_shared uses the backref walking code but will short
1450 * circuit as soon as it finds a root or inode that doesn't match the
1451 * one passed in. This provides a significant performance benefit for
1452 * callers (such as fiemap) which want to know whether the extent is
1453 * shared but do not need a ref count.
1454 *
1455 * This attempts to allocate a transaction in order to account for
1456 * delayed refs, but continues on even when the alloc fails.
1457 *
1458 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1459 */
1460int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
1461{
1462 struct btrfs_fs_info *fs_info = root->fs_info;
1463 struct btrfs_trans_handle *trans;
1464 struct ulist *tmp = NULL;
1465 struct ulist *roots = NULL;
1466 struct ulist_iterator uiter;
1467 struct ulist_node *node;
1468 struct seq_list elem = SEQ_LIST_INIT(elem);
1469 int ret = 0;
1470 struct share_check shared = {
1471 .root_objectid = root->objectid,
1472 .inum = inum,
1473 .share_count = 0,
1474 };
1475
1476 tmp = ulist_alloc(GFP_NOFS);
1477 roots = ulist_alloc(GFP_NOFS);
1478 if (!tmp || !roots) {
1479 ulist_free(tmp);
1480 ulist_free(roots);
1481 return -ENOMEM;
1482 }
1483
1484 trans = btrfs_join_transaction(root);
1485 if (IS_ERR(trans)) {
1486 trans = NULL;
1487 down_read(&fs_info->commit_root_sem);
1488 } else {
1489 btrfs_get_tree_mod_seq(fs_info, &elem);
1490 }
1491
1492 ULIST_ITER_INIT(&uiter);
1493 while (1) {
1494 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1495 roots, NULL, &shared, false);
1496 if (ret == BACKREF_FOUND_SHARED) {
1497 /* this is the only condition under which we return 1 */
1498 ret = 1;
1499 break;
1500 }
1501 if (ret < 0 && ret != -ENOENT)
1502 break;
1503 ret = 0;
1504 node = ulist_next(tmp, &uiter);
1505 if (!node)
1506 break;
1507 bytenr = node->val;
1508 shared.share_count = 0;
1509 cond_resched();
1510 }
1511
1512 if (trans) {
1513 btrfs_put_tree_mod_seq(fs_info, &elem);
1514 btrfs_end_transaction(trans);
1515 } else {
1516 up_read(&fs_info->commit_root_sem);
1517 }
1518 ulist_free(tmp);
1519 ulist_free(roots);
1520 return ret;
1521}
1522
1523int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1524 u64 start_off, struct btrfs_path *path,
1525 struct btrfs_inode_extref **ret_extref,
1526 u64 *found_off)
1527{
1528 int ret, slot;
1529 struct btrfs_key key;
1530 struct btrfs_key found_key;
1531 struct btrfs_inode_extref *extref;
1532 const struct extent_buffer *leaf;
1533 unsigned long ptr;
1534
1535 key.objectid = inode_objectid;
1536 key.type = BTRFS_INODE_EXTREF_KEY;
1537 key.offset = start_off;
1538
1539 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1540 if (ret < 0)
1541 return ret;
1542
1543 while (1) {
1544 leaf = path->nodes[0];
1545 slot = path->slots[0];
1546 if (slot >= btrfs_header_nritems(leaf)) {
1547 /*
1548 * If the item at offset is not found,
1549 * btrfs_search_slot will point us to the slot
1550 * where it should be inserted. In our case
1551 * that will be the slot directly before the
1552 * next INODE_REF_KEY_V2 item. In the case
1553 * that we're pointing to the last slot in a
1554 * leaf, we must move one leaf over.
1555 */
1556 ret = btrfs_next_leaf(root, path);
1557 if (ret) {
1558 if (ret >= 1)
1559 ret = -ENOENT;
1560 break;
1561 }
1562 continue;
1563 }
1564
1565 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1566
1567 /*
1568 * Check that we're still looking at an extended ref key for
1569 * this particular objectid. If we have different
1570 * objectid or type then there are no more to be found
1571 * in the tree and we can exit.
1572 */
1573 ret = -ENOENT;
1574 if (found_key.objectid != inode_objectid)
1575 break;
1576 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1577 break;
1578
1579 ret = 0;
1580 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1581 extref = (struct btrfs_inode_extref *)ptr;
1582 *ret_extref = extref;
1583 if (found_off)
1584 *found_off = found_key.offset;
1585 break;
1586 }
1587
1588 return ret;
1589}
1590
1591/*
1592 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1593 * Elements of the path are separated by '/' and the path is guaranteed to be
1594 * 0-terminated. the path is only given within the current file system.
1595 * Therefore, it never starts with a '/'. the caller is responsible to provide
1596 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1597 * the start point of the resulting string is returned. this pointer is within
1598 * dest, normally.
1599 * in case the path buffer would overflow, the pointer is decremented further
1600 * as if output was written to the buffer, though no more output is actually
1601 * generated. that way, the caller can determine how much space would be
1602 * required for the path to fit into the buffer. in that case, the returned
1603 * value will be smaller than dest. callers must check this!
1604 */
1605char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1606 u32 name_len, unsigned long name_off,
1607 struct extent_buffer *eb_in, u64 parent,
1608 char *dest, u32 size)
1609{
1610 int slot;
1611 u64 next_inum;
1612 int ret;
1613 s64 bytes_left = ((s64)size) - 1;
1614 struct extent_buffer *eb = eb_in;
1615 struct btrfs_key found_key;
1616 int leave_spinning = path->leave_spinning;
1617 struct btrfs_inode_ref *iref;
1618
1619 if (bytes_left >= 0)
1620 dest[bytes_left] = '\0';
1621
1622 path->leave_spinning = 1;
1623 while (1) {
1624 bytes_left -= name_len;
1625 if (bytes_left >= 0)
1626 read_extent_buffer(eb, dest + bytes_left,
1627 name_off, name_len);
1628 if (eb != eb_in) {
1629 if (!path->skip_locking)
1630 btrfs_tree_read_unlock_blocking(eb);
1631 free_extent_buffer(eb);
1632 }
1633 ret = btrfs_find_item(fs_root, path, parent, 0,
1634 BTRFS_INODE_REF_KEY, &found_key);
1635 if (ret > 0)
1636 ret = -ENOENT;
1637 if (ret)
1638 break;
1639
1640 next_inum = found_key.offset;
1641
1642 /* regular exit ahead */
1643 if (parent == next_inum)
1644 break;
1645
1646 slot = path->slots[0];
1647 eb = path->nodes[0];
1648 /* make sure we can use eb after releasing the path */
1649 if (eb != eb_in) {
1650 if (!path->skip_locking)
1651 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1652 path->nodes[0] = NULL;
1653 path->locks[0] = 0;
1654 }
1655 btrfs_release_path(path);
1656 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1657
1658 name_len = btrfs_inode_ref_name_len(eb, iref);
1659 name_off = (unsigned long)(iref + 1);
1660
1661 parent = next_inum;
1662 --bytes_left;
1663 if (bytes_left >= 0)
1664 dest[bytes_left] = '/';
1665 }
1666
1667 btrfs_release_path(path);
1668 path->leave_spinning = leave_spinning;
1669
1670 if (ret)
1671 return ERR_PTR(ret);
1672
1673 return dest + bytes_left;
1674}
1675
1676/*
1677 * this makes the path point to (logical EXTENT_ITEM *)
1678 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1679 * tree blocks and <0 on error.
1680 */
1681int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1682 struct btrfs_path *path, struct btrfs_key *found_key,
1683 u64 *flags_ret)
1684{
1685 int ret;
1686 u64 flags;
1687 u64 size = 0;
1688 u32 item_size;
1689 const struct extent_buffer *eb;
1690 struct btrfs_extent_item *ei;
1691 struct btrfs_key key;
1692
1693 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1694 key.type = BTRFS_METADATA_ITEM_KEY;
1695 else
1696 key.type = BTRFS_EXTENT_ITEM_KEY;
1697 key.objectid = logical;
1698 key.offset = (u64)-1;
1699
1700 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1701 if (ret < 0)
1702 return ret;
1703
1704 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1705 if (ret) {
1706 if (ret > 0)
1707 ret = -ENOENT;
1708 return ret;
1709 }
1710 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1711 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1712 size = fs_info->nodesize;
1713 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1714 size = found_key->offset;
1715
1716 if (found_key->objectid > logical ||
1717 found_key->objectid + size <= logical) {
1718 btrfs_debug(fs_info,
1719 "logical %llu is not within any extent", logical);
1720 return -ENOENT;
1721 }
1722
1723 eb = path->nodes[0];
1724 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1725 BUG_ON(item_size < sizeof(*ei));
1726
1727 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1728 flags = btrfs_extent_flags(eb, ei);
1729
1730 btrfs_debug(fs_info,
1731 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1732 logical, logical - found_key->objectid, found_key->objectid,
1733 found_key->offset, flags, item_size);
1734
1735 WARN_ON(!flags_ret);
1736 if (flags_ret) {
1737 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1738 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1739 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1740 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1741 else
1742 BUG_ON(1);
1743 return 0;
1744 }
1745
1746 return -EIO;
1747}
1748
1749/*
1750 * helper function to iterate extent inline refs. ptr must point to a 0 value
1751 * for the first call and may be modified. it is used to track state.
1752 * if more refs exist, 0 is returned and the next call to
1753 * get_extent_inline_ref must pass the modified ptr parameter to get the
1754 * next ref. after the last ref was processed, 1 is returned.
1755 * returns <0 on error
1756 */
1757static int get_extent_inline_ref(unsigned long *ptr,
1758 const struct extent_buffer *eb,
1759 const struct btrfs_key *key,
1760 const struct btrfs_extent_item *ei,
1761 u32 item_size,
1762 struct btrfs_extent_inline_ref **out_eiref,
1763 int *out_type)
1764{
1765 unsigned long end;
1766 u64 flags;
1767 struct btrfs_tree_block_info *info;
1768
1769 if (!*ptr) {
1770 /* first call */
1771 flags = btrfs_extent_flags(eb, ei);
1772 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1773 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1774 /* a skinny metadata extent */
1775 *out_eiref =
1776 (struct btrfs_extent_inline_ref *)(ei + 1);
1777 } else {
1778 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1779 info = (struct btrfs_tree_block_info *)(ei + 1);
1780 *out_eiref =
1781 (struct btrfs_extent_inline_ref *)(info + 1);
1782 }
1783 } else {
1784 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1785 }
1786 *ptr = (unsigned long)*out_eiref;
1787 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1788 return -ENOENT;
1789 }
1790
1791 end = (unsigned long)ei + item_size;
1792 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1793 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
1794 BTRFS_REF_TYPE_ANY);
1795 if (*out_type == BTRFS_REF_TYPE_INVALID)
1796 return -EINVAL;
1797
1798 *ptr += btrfs_extent_inline_ref_size(*out_type);
1799 WARN_ON(*ptr > end);
1800 if (*ptr == end)
1801 return 1; /* last */
1802
1803 return 0;
1804}
1805
1806/*
1807 * reads the tree block backref for an extent. tree level and root are returned
1808 * through out_level and out_root. ptr must point to a 0 value for the first
1809 * call and may be modified (see get_extent_inline_ref comment).
1810 * returns 0 if data was provided, 1 if there was no more data to provide or
1811 * <0 on error.
1812 */
1813int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1814 struct btrfs_key *key, struct btrfs_extent_item *ei,
1815 u32 item_size, u64 *out_root, u8 *out_level)
1816{
1817 int ret;
1818 int type;
1819 struct btrfs_extent_inline_ref *eiref;
1820
1821 if (*ptr == (unsigned long)-1)
1822 return 1;
1823
1824 while (1) {
1825 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
1826 &eiref, &type);
1827 if (ret < 0)
1828 return ret;
1829
1830 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1831 type == BTRFS_SHARED_BLOCK_REF_KEY)
1832 break;
1833
1834 if (ret == 1)
1835 return 1;
1836 }
1837
1838 /* we can treat both ref types equally here */
1839 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1840
1841 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1842 struct btrfs_tree_block_info *info;
1843
1844 info = (struct btrfs_tree_block_info *)(ei + 1);
1845 *out_level = btrfs_tree_block_level(eb, info);
1846 } else {
1847 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1848 *out_level = (u8)key->offset;
1849 }
1850
1851 if (ret == 1)
1852 *ptr = (unsigned long)-1;
1853
1854 return 0;
1855}
1856
1857static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1858 struct extent_inode_elem *inode_list,
1859 u64 root, u64 extent_item_objectid,
1860 iterate_extent_inodes_t *iterate, void *ctx)
1861{
1862 struct extent_inode_elem *eie;
1863 int ret = 0;
1864
1865 for (eie = inode_list; eie; eie = eie->next) {
1866 btrfs_debug(fs_info,
1867 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1868 extent_item_objectid, eie->inum,
1869 eie->offset, root);
1870 ret = iterate(eie->inum, eie->offset, root, ctx);
1871 if (ret) {
1872 btrfs_debug(fs_info,
1873 "stopping iteration for %llu due to ret=%d",
1874 extent_item_objectid, ret);
1875 break;
1876 }
1877 }
1878
1879 return ret;
1880}
1881
1882/*
1883 * calls iterate() for every inode that references the extent identified by
1884 * the given parameters.
1885 * when the iterator function returns a non-zero value, iteration stops.
1886 */
1887int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1888 u64 extent_item_objectid, u64 extent_item_pos,
1889 int search_commit_root,
1890 iterate_extent_inodes_t *iterate, void *ctx,
1891 bool ignore_offset)
1892{
1893 int ret;
1894 struct btrfs_trans_handle *trans = NULL;
1895 struct ulist *refs = NULL;
1896 struct ulist *roots = NULL;
1897 struct ulist_node *ref_node = NULL;
1898 struct ulist_node *root_node = NULL;
1899 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
1900 struct ulist_iterator ref_uiter;
1901 struct ulist_iterator root_uiter;
1902
1903 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
1904 extent_item_objectid);
1905
1906 if (!search_commit_root) {
1907 trans = btrfs_join_transaction(fs_info->extent_root);
1908 if (IS_ERR(trans))
1909 return PTR_ERR(trans);
1910 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1911 } else {
1912 down_read(&fs_info->commit_root_sem);
1913 }
1914
1915 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1916 tree_mod_seq_elem.seq, &refs,
1917 &extent_item_pos, ignore_offset);
1918 if (ret)
1919 goto out;
1920
1921 ULIST_ITER_INIT(&ref_uiter);
1922 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1923 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val,
1924 tree_mod_seq_elem.seq, &roots,
1925 ignore_offset);
1926 if (ret)
1927 break;
1928 ULIST_ITER_INIT(&root_uiter);
1929 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1930 btrfs_debug(fs_info,
1931 "root %llu references leaf %llu, data list %#llx",
1932 root_node->val, ref_node->val,
1933 ref_node->aux);
1934 ret = iterate_leaf_refs(fs_info,
1935 (struct extent_inode_elem *)
1936 (uintptr_t)ref_node->aux,
1937 root_node->val,
1938 extent_item_objectid,
1939 iterate, ctx);
1940 }
1941 ulist_free(roots);
1942 }
1943
1944 free_leaf_list(refs);
1945out:
1946 if (!search_commit_root) {
1947 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1948 btrfs_end_transaction(trans);
1949 } else {
1950 up_read(&fs_info->commit_root_sem);
1951 }
1952
1953 return ret;
1954}
1955
1956int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1957 struct btrfs_path *path,
1958 iterate_extent_inodes_t *iterate, void *ctx,
1959 bool ignore_offset)
1960{
1961 int ret;
1962 u64 extent_item_pos;
1963 u64 flags = 0;
1964 struct btrfs_key found_key;
1965 int search_commit_root = path->search_commit_root;
1966
1967 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1968 btrfs_release_path(path);
1969 if (ret < 0)
1970 return ret;
1971 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1972 return -EINVAL;
1973
1974 extent_item_pos = logical - found_key.objectid;
1975 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1976 extent_item_pos, search_commit_root,
1977 iterate, ctx, ignore_offset);
1978
1979 return ret;
1980}
1981
1982typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1983 struct extent_buffer *eb, void *ctx);
1984
1985static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1986 struct btrfs_path *path,
1987 iterate_irefs_t *iterate, void *ctx)
1988{
1989 int ret = 0;
1990 int slot;
1991 u32 cur;
1992 u32 len;
1993 u32 name_len;
1994 u64 parent = 0;
1995 int found = 0;
1996 struct extent_buffer *eb;
1997 struct btrfs_item *item;
1998 struct btrfs_inode_ref *iref;
1999 struct btrfs_key found_key;
2000
2001 while (!ret) {
2002 ret = btrfs_find_item(fs_root, path, inum,
2003 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2004 &found_key);
2005
2006 if (ret < 0)
2007 break;
2008 if (ret) {
2009 ret = found ? 0 : -ENOENT;
2010 break;
2011 }
2012 ++found;
2013
2014 parent = found_key.offset;
2015 slot = path->slots[0];
2016 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2017 if (!eb) {
2018 ret = -ENOMEM;
2019 break;
2020 }
2021 extent_buffer_get(eb);
2022 btrfs_tree_read_lock(eb);
2023 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2024 btrfs_release_path(path);
2025
2026 item = btrfs_item_nr(slot);
2027 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2028
2029 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
2030 name_len = btrfs_inode_ref_name_len(eb, iref);
2031 /* path must be released before calling iterate()! */
2032 btrfs_debug(fs_root->fs_info,
2033 "following ref at offset %u for inode %llu in tree %llu",
2034 cur, found_key.objectid, fs_root->objectid);
2035 ret = iterate(parent, name_len,
2036 (unsigned long)(iref + 1), eb, ctx);
2037 if (ret)
2038 break;
2039 len = sizeof(*iref) + name_len;
2040 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2041 }
2042 btrfs_tree_read_unlock_blocking(eb);
2043 free_extent_buffer(eb);
2044 }
2045
2046 btrfs_release_path(path);
2047
2048 return ret;
2049}
2050
2051static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
2052 struct btrfs_path *path,
2053 iterate_irefs_t *iterate, void *ctx)
2054{
2055 int ret;
2056 int slot;
2057 u64 offset = 0;
2058 u64 parent;
2059 int found = 0;
2060 struct extent_buffer *eb;
2061 struct btrfs_inode_extref *extref;
2062 u32 item_size;
2063 u32 cur_offset;
2064 unsigned long ptr;
2065
2066 while (1) {
2067 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2068 &offset);
2069 if (ret < 0)
2070 break;
2071 if (ret) {
2072 ret = found ? 0 : -ENOENT;
2073 break;
2074 }
2075 ++found;
2076
2077 slot = path->slots[0];
2078 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2079 if (!eb) {
2080 ret = -ENOMEM;
2081 break;
2082 }
2083 extent_buffer_get(eb);
2084
2085 btrfs_tree_read_lock(eb);
2086 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2087 btrfs_release_path(path);
2088
2089 item_size = btrfs_item_size_nr(eb, slot);
2090 ptr = btrfs_item_ptr_offset(eb, slot);
2091 cur_offset = 0;
2092
2093 while (cur_offset < item_size) {
2094 u32 name_len;
2095
2096 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2097 parent = btrfs_inode_extref_parent(eb, extref);
2098 name_len = btrfs_inode_extref_name_len(eb, extref);
2099 ret = iterate(parent, name_len,
2100 (unsigned long)&extref->name, eb, ctx);
2101 if (ret)
2102 break;
2103
2104 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2105 cur_offset += sizeof(*extref);
2106 }
2107 btrfs_tree_read_unlock_blocking(eb);
2108 free_extent_buffer(eb);
2109
2110 offset++;
2111 }
2112
2113 btrfs_release_path(path);
2114
2115 return ret;
2116}
2117
2118static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
2119 struct btrfs_path *path, iterate_irefs_t *iterate,
2120 void *ctx)
2121{
2122 int ret;
2123 int found_refs = 0;
2124
2125 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
2126 if (!ret)
2127 ++found_refs;
2128 else if (ret != -ENOENT)
2129 return ret;
2130
2131 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
2132 if (ret == -ENOENT && found_refs)
2133 return 0;
2134
2135 return ret;
2136}
2137
2138/*
2139 * returns 0 if the path could be dumped (probably truncated)
2140 * returns <0 in case of an error
2141 */
2142static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2143 struct extent_buffer *eb, void *ctx)
2144{
2145 struct inode_fs_paths *ipath = ctx;
2146 char *fspath;
2147 char *fspath_min;
2148 int i = ipath->fspath->elem_cnt;
2149 const int s_ptr = sizeof(char *);
2150 u32 bytes_left;
2151
2152 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2153 ipath->fspath->bytes_left - s_ptr : 0;
2154
2155 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2156 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2157 name_off, eb, inum, fspath_min, bytes_left);
2158 if (IS_ERR(fspath))
2159 return PTR_ERR(fspath);
2160
2161 if (fspath > fspath_min) {
2162 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2163 ++ipath->fspath->elem_cnt;
2164 ipath->fspath->bytes_left = fspath - fspath_min;
2165 } else {
2166 ++ipath->fspath->elem_missed;
2167 ipath->fspath->bytes_missing += fspath_min - fspath;
2168 ipath->fspath->bytes_left = 0;
2169 }
2170
2171 return 0;
2172}
2173
2174/*
2175 * this dumps all file system paths to the inode into the ipath struct, provided
2176 * is has been created large enough. each path is zero-terminated and accessed
2177 * from ipath->fspath->val[i].
2178 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2179 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2180 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2181 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2182 * have been needed to return all paths.
2183 */
2184int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2185{
2186 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
2187 inode_to_path, ipath);
2188}
2189
2190struct btrfs_data_container *init_data_container(u32 total_bytes)
2191{
2192 struct btrfs_data_container *data;
2193 size_t alloc_bytes;
2194
2195 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2196 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2197 if (!data)
2198 return ERR_PTR(-ENOMEM);
2199
2200 if (total_bytes >= sizeof(*data)) {
2201 data->bytes_left = total_bytes - sizeof(*data);
2202 data->bytes_missing = 0;
2203 } else {
2204 data->bytes_missing = sizeof(*data) - total_bytes;
2205 data->bytes_left = 0;
2206 }
2207
2208 data->elem_cnt = 0;
2209 data->elem_missed = 0;
2210
2211 return data;
2212}
2213
2214/*
2215 * allocates space to return multiple file system paths for an inode.
2216 * total_bytes to allocate are passed, note that space usable for actual path
2217 * information will be total_bytes - sizeof(struct inode_fs_paths).
2218 * the returned pointer must be freed with free_ipath() in the end.
2219 */
2220struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2221 struct btrfs_path *path)
2222{
2223 struct inode_fs_paths *ifp;
2224 struct btrfs_data_container *fspath;
2225
2226 fspath = init_data_container(total_bytes);
2227 if (IS_ERR(fspath))
2228 return (void *)fspath;
2229
2230 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2231 if (!ifp) {
2232 kvfree(fspath);
2233 return ERR_PTR(-ENOMEM);
2234 }
2235
2236 ifp->btrfs_path = path;
2237 ifp->fspath = fspath;
2238 ifp->fs_root = fs_root;
2239
2240 return ifp;
2241}
2242
2243void free_ipath(struct inode_fs_paths *ipath)
2244{
2245 if (!ipath)
2246 return;
2247 kvfree(ipath->fspath);
2248 kfree(ipath);
2249}