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perf bpf: Move perf_event_output() from stdio.h to bpf.h
[linux/fpc-iii.git] / fs / btrfs / backref.c
blob68ebe188446acb88d67eb5341dac78acc8594c8d
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
20 struct extent_inode_elem {
21 u64 inum;
22 u64 offset;
23 struct extent_inode_elem *next;
24 };
25
26 static 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
64 static 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
74 static 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
114 struct preftree {
115 struct rb_root_cached root;
116 unsigned int count;
117 };
118
119 #define PREFTREE_INIT { .root = RB_ROOT_CACHED, .count = 0 }
120
121 struct 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 */
135 struct share_check {
136 u64 root_objectid;
137 u64 inum;
138 int share_count;
139 };
140
141 static inline int extent_is_shared(struct share_check *sc)
142 {
143 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
144 }
145
146 static struct kmem_cache *btrfs_prelim_ref_cache;
147
148 int __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
160 void __cold btrfs_prelim_ref_exit(void)
161 {
162 kmem_cache_destroy(btrfs_prelim_ref_cache);
163 }
164
165 static 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 */
175 static 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
206 static 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 */
223 static 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_cached *root;
229 struct rb_node **p;
230 struct rb_node *parent = NULL;
231 struct prelim_ref *ref;
232 int result;
233 bool leftmost = true;
234
235 root = &preftree->root;
236 p = &root->rb_root.rb_node;
237
238 while (*p) {
239 parent = *p;
240 ref = rb_entry(parent, struct prelim_ref, rbnode);
241 result = prelim_ref_compare(ref, newref);
242 if (result < 0) {
243 p = &(*p)->rb_left;
244 } else if (result > 0) {
245 p = &(*p)->rb_right;
246 leftmost = false;
247 } else {
248 /* Identical refs, merge them and free @newref */
249 struct extent_inode_elem *eie = ref->inode_list;
250
251 while (eie && eie->next)
252 eie = eie->next;
253
254 if (!eie)
255 ref->inode_list = newref->inode_list;
256 else
257 eie->next = newref->inode_list;
258 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
259 preftree->count);
260 /*
261 * A delayed ref can have newref->count < 0.
262 * The ref->count is updated to follow any
263 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
264 */
265 update_share_count(sc, ref->count,
266 ref->count + newref->count);
267 ref->count += newref->count;
268 free_pref(newref);
269 return;
270 }
271 }
272
273 update_share_count(sc, 0, newref->count);
274 preftree->count++;
275 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
276 rb_link_node(&newref->rbnode, parent, p);
277 rb_insert_color_cached(&newref->rbnode, root, leftmost);
278 }
279
280 /*
281 * Release the entire tree. We don't care about internal consistency so
282 * just free everything and then reset the tree root.
283 */
284 static void prelim_release(struct preftree *preftree)
285 {
286 struct prelim_ref *ref, *next_ref;
287
288 rbtree_postorder_for_each_entry_safe(ref, next_ref,
289 &preftree->root.rb_root, rbnode)
290 free_pref(ref);
291
292 preftree->root = RB_ROOT_CACHED;
293 preftree->count = 0;
294 }
295
296 /*
297 * the rules for all callers of this function are:
298 * - obtaining the parent is the goal
299 * - if you add a key, you must know that it is a correct key
300 * - if you cannot add the parent or a correct key, then we will look into the
301 * block later to set a correct key
302 *
303 * delayed refs
304 * ============
305 * backref type | shared | indirect | shared | indirect
306 * information | tree | tree | data | data
307 * --------------------+--------+----------+--------+----------
308 * parent logical | y | - | - | -
309 * key to resolve | - | y | y | y
310 * tree block logical | - | - | - | -
311 * root for resolving | y | y | y | y
312 *
313 * - column 1: we've the parent -> done
314 * - column 2, 3, 4: we use the key to find the parent
315 *
316 * on disk refs (inline or keyed)
317 * ==============================
318 * backref type | shared | indirect | shared | indirect
319 * information | tree | tree | data | data
320 * --------------------+--------+----------+--------+----------
321 * parent logical | y | - | y | -
322 * key to resolve | - | - | - | y
323 * tree block logical | y | y | y | y
324 * root for resolving | - | y | y | y
325 *
326 * - column 1, 3: we've the parent -> done
327 * - column 2: we take the first key from the block to find the parent
328 * (see add_missing_keys)
329 * - column 4: we use the key to find the parent
330 *
331 * additional information that's available but not required to find the parent
332 * block might help in merging entries to gain some speed.
333 */
334 static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
335 struct preftree *preftree, u64 root_id,
336 const struct btrfs_key *key, int level, u64 parent,
337 u64 wanted_disk_byte, int count,
338 struct share_check *sc, gfp_t gfp_mask)
339 {
340 struct prelim_ref *ref;
341
342 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
343 return 0;
344
345 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
346 if (!ref)
347 return -ENOMEM;
348
349 ref->root_id = root_id;
350 if (key) {
351 ref->key_for_search = *key;
352 /*
353 * We can often find data backrefs with an offset that is too
354 * large (>= LLONG_MAX, maximum allowed file offset) due to
355 * underflows when subtracting a file's offset with the data
356 * offset of its corresponding extent data item. This can
357 * happen for example in the clone ioctl.
358 * So if we detect such case we set the search key's offset to
359 * zero to make sure we will find the matching file extent item
360 * at add_all_parents(), otherwise we will miss it because the
361 * offset taken form the backref is much larger then the offset
362 * of the file extent item. This can make us scan a very large
363 * number of file extent items, but at least it will not make
364 * us miss any.
365 * This is an ugly workaround for a behaviour that should have
366 * never existed, but it does and a fix for the clone ioctl
367 * would touch a lot of places, cause backwards incompatibility
368 * and would not fix the problem for extents cloned with older
369 * kernels.
370 */
371 if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY &&
372 ref->key_for_search.offset >= LLONG_MAX)
373 ref->key_for_search.offset = 0;
374 } else {
375 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
376 }
377
378 ref->inode_list = NULL;
379 ref->level = level;
380 ref->count = count;
381 ref->parent = parent;
382 ref->wanted_disk_byte = wanted_disk_byte;
383 prelim_ref_insert(fs_info, preftree, ref, sc);
384 return extent_is_shared(sc);
385 }
386
387 /* direct refs use root == 0, key == NULL */
388 static int add_direct_ref(const struct btrfs_fs_info *fs_info,
389 struct preftrees *preftrees, int level, u64 parent,
390 u64 wanted_disk_byte, int count,
391 struct share_check *sc, gfp_t gfp_mask)
392 {
393 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
394 parent, wanted_disk_byte, count, sc, gfp_mask);
395 }
396
397 /* indirect refs use parent == 0 */
398 static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
399 struct preftrees *preftrees, u64 root_id,
400 const struct btrfs_key *key, int level,
401 u64 wanted_disk_byte, int count,
402 struct share_check *sc, gfp_t gfp_mask)
403 {
404 struct preftree *tree = &preftrees->indirect;
405
406 if (!key)
407 tree = &preftrees->indirect_missing_keys;
408 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
409 wanted_disk_byte, count, sc, gfp_mask);
410 }
411
412 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
413 struct ulist *parents, struct prelim_ref *ref,
414 int level, u64 time_seq, const u64 *extent_item_pos,
415 u64 total_refs, bool ignore_offset)
416 {
417 int ret = 0;
418 int slot;
419 struct extent_buffer *eb;
420 struct btrfs_key key;
421 struct btrfs_key *key_for_search = &ref->key_for_search;
422 struct btrfs_file_extent_item *fi;
423 struct extent_inode_elem *eie = NULL, *old = NULL;
424 u64 disk_byte;
425 u64 wanted_disk_byte = ref->wanted_disk_byte;
426 u64 count = 0;
427
428 if (level != 0) {
429 eb = path->nodes[level];
430 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
431 if (ret < 0)
432 return ret;
433 return 0;
434 }
435
436 /*
437 * We normally enter this function with the path already pointing to
438 * the first item to check. But sometimes, we may enter it with
439 * slot==nritems. In that case, go to the next leaf before we continue.
440 */
441 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
442 if (time_seq == SEQ_LAST)
443 ret = btrfs_next_leaf(root, path);
444 else
445 ret = btrfs_next_old_leaf(root, path, time_seq);
446 }
447
448 while (!ret && count < total_refs) {
449 eb = path->nodes[0];
450 slot = path->slots[0];
451
452 btrfs_item_key_to_cpu(eb, &key, slot);
453
454 if (key.objectid != key_for_search->objectid ||
455 key.type != BTRFS_EXTENT_DATA_KEY)
456 break;
457
458 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
459 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
460
461 if (disk_byte == wanted_disk_byte) {
462 eie = NULL;
463 old = NULL;
464 count++;
465 if (extent_item_pos) {
466 ret = check_extent_in_eb(&key, eb, fi,
467 *extent_item_pos,
468 &eie, ignore_offset);
469 if (ret < 0)
470 break;
471 }
472 if (ret > 0)
473 goto next;
474 ret = ulist_add_merge_ptr(parents, eb->start,
475 eie, (void **)&old, GFP_NOFS);
476 if (ret < 0)
477 break;
478 if (!ret && extent_item_pos) {
479 while (old->next)
480 old = old->next;
481 old->next = eie;
482 }
483 eie = NULL;
484 }
485 next:
486 if (time_seq == SEQ_LAST)
487 ret = btrfs_next_item(root, path);
488 else
489 ret = btrfs_next_old_item(root, path, time_seq);
490 }
491
492 if (ret > 0)
493 ret = 0;
494 else if (ret < 0)
495 free_inode_elem_list(eie);
496 return ret;
497 }
498
499 /*
500 * resolve an indirect backref in the form (root_id, key, level)
501 * to a logical address
502 */
503 static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
504 struct btrfs_path *path, u64 time_seq,
505 struct prelim_ref *ref, struct ulist *parents,
506 const u64 *extent_item_pos, u64 total_refs,
507 bool ignore_offset)
508 {
509 struct btrfs_root *root;
510 struct btrfs_key root_key;
511 struct extent_buffer *eb;
512 int ret = 0;
513 int root_level;
514 int level = ref->level;
515 int index;
516
517 root_key.objectid = ref->root_id;
518 root_key.type = BTRFS_ROOT_ITEM_KEY;
519 root_key.offset = (u64)-1;
520
521 index = srcu_read_lock(&fs_info->subvol_srcu);
522
523 root = btrfs_get_fs_root(fs_info, &root_key, false);
524 if (IS_ERR(root)) {
525 srcu_read_unlock(&fs_info->subvol_srcu, index);
526 ret = PTR_ERR(root);
527 goto out;
528 }
529
530 if (btrfs_is_testing(fs_info)) {
531 srcu_read_unlock(&fs_info->subvol_srcu, index);
532 ret = -ENOENT;
533 goto out;
534 }
535
536 if (path->search_commit_root)
537 root_level = btrfs_header_level(root->commit_root);
538 else if (time_seq == SEQ_LAST)
539 root_level = btrfs_header_level(root->node);
540 else
541 root_level = btrfs_old_root_level(root, time_seq);
542
543 if (root_level + 1 == level) {
544 srcu_read_unlock(&fs_info->subvol_srcu, index);
545 goto out;
546 }
547
548 path->lowest_level = level;
549 if (time_seq == SEQ_LAST)
550 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path,
551 0, 0);
552 else
553 ret = btrfs_search_old_slot(root, &ref->key_for_search, path,
554 time_seq);
555
556 /* root node has been locked, we can release @subvol_srcu safely here */
557 srcu_read_unlock(&fs_info->subvol_srcu, index);
558
559 btrfs_debug(fs_info,
560 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
561 ref->root_id, level, ref->count, ret,
562 ref->key_for_search.objectid, ref->key_for_search.type,
563 ref->key_for_search.offset);
564 if (ret < 0)
565 goto out;
566
567 eb = path->nodes[level];
568 while (!eb) {
569 if (WARN_ON(!level)) {
570 ret = 1;
571 goto out;
572 }
573 level--;
574 eb = path->nodes[level];
575 }
576
577 ret = add_all_parents(root, path, parents, ref, level, time_seq,
578 extent_item_pos, total_refs, ignore_offset);
579 out:
580 path->lowest_level = 0;
581 btrfs_release_path(path);
582 return ret;
583 }
584
585 static struct extent_inode_elem *
586 unode_aux_to_inode_list(struct ulist_node *node)
587 {
588 if (!node)
589 return NULL;
590 return (struct extent_inode_elem *)(uintptr_t)node->aux;
591 }
592
593 /*
594 * We maintain three seperate rbtrees: one for direct refs, one for
595 * indirect refs which have a key, and one for indirect refs which do not
596 * have a key. Each tree does merge on insertion.
597 *
598 * Once all of the references are located, we iterate over the tree of
599 * indirect refs with missing keys. An appropriate key is located and
600 * the ref is moved onto the tree for indirect refs. After all missing
601 * keys are thus located, we iterate over the indirect ref tree, resolve
602 * each reference, and then insert the resolved reference onto the
603 * direct tree (merging there too).
604 *
605 * New backrefs (i.e., for parent nodes) are added to the appropriate
606 * rbtree as they are encountered. The new backrefs are subsequently
607 * resolved as above.
608 */
609 static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
610 struct btrfs_path *path, u64 time_seq,
611 struct preftrees *preftrees,
612 const u64 *extent_item_pos, u64 total_refs,
613 struct share_check *sc, bool ignore_offset)
614 {
615 int err;
616 int ret = 0;
617 struct ulist *parents;
618 struct ulist_node *node;
619 struct ulist_iterator uiter;
620 struct rb_node *rnode;
621
622 parents = ulist_alloc(GFP_NOFS);
623 if (!parents)
624 return -ENOMEM;
625
626 /*
627 * We could trade memory usage for performance here by iterating
628 * the tree, allocating new refs for each insertion, and then
629 * freeing the entire indirect tree when we're done. In some test
630 * cases, the tree can grow quite large (~200k objects).
631 */
632 while ((rnode = rb_first_cached(&preftrees->indirect.root))) {
633 struct prelim_ref *ref;
634
635 ref = rb_entry(rnode, struct prelim_ref, rbnode);
636 if (WARN(ref->parent,
637 "BUG: direct ref found in indirect tree")) {
638 ret = -EINVAL;
639 goto out;
640 }
641
642 rb_erase_cached(&ref->rbnode, &preftrees->indirect.root);
643 preftrees->indirect.count--;
644
645 if (ref->count == 0) {
646 free_pref(ref);
647 continue;
648 }
649
650 if (sc && sc->root_objectid &&
651 ref->root_id != sc->root_objectid) {
652 free_pref(ref);
653 ret = BACKREF_FOUND_SHARED;
654 goto out;
655 }
656 err = resolve_indirect_ref(fs_info, path, time_seq, ref,
657 parents, extent_item_pos,
658 total_refs, ignore_offset);
659 /*
660 * we can only tolerate ENOENT,otherwise,we should catch error
661 * and return directly.
662 */
663 if (err == -ENOENT) {
664 prelim_ref_insert(fs_info, &preftrees->direct, ref,
665 NULL);
666 continue;
667 } else if (err) {
668 free_pref(ref);
669 ret = err;
670 goto out;
671 }
672
673 /* we put the first parent into the ref at hand */
674 ULIST_ITER_INIT(&uiter);
675 node = ulist_next(parents, &uiter);
676 ref->parent = node ? node->val : 0;
677 ref->inode_list = unode_aux_to_inode_list(node);
678
679 /* Add a prelim_ref(s) for any other parent(s). */
680 while ((node = ulist_next(parents, &uiter))) {
681 struct prelim_ref *new_ref;
682
683 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
684 GFP_NOFS);
685 if (!new_ref) {
686 free_pref(ref);
687 ret = -ENOMEM;
688 goto out;
689 }
690 memcpy(new_ref, ref, sizeof(*ref));
691 new_ref->parent = node->val;
692 new_ref->inode_list = unode_aux_to_inode_list(node);
693 prelim_ref_insert(fs_info, &preftrees->direct,
694 new_ref, NULL);
695 }
696
697 /*
698 * Now it's a direct ref, put it in the the direct tree. We must
699 * do this last because the ref could be merged/freed here.
700 */
701 prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL);
702
703 ulist_reinit(parents);
704 cond_resched();
705 }
706 out:
707 ulist_free(parents);
708 return ret;
709 }
710
711 /*
712 * read tree blocks and add keys where required.
713 */
714 static int add_missing_keys(struct btrfs_fs_info *fs_info,
715 struct preftrees *preftrees)
716 {
717 struct prelim_ref *ref;
718 struct extent_buffer *eb;
719 struct preftree *tree = &preftrees->indirect_missing_keys;
720 struct rb_node *node;
721
722 while ((node = rb_first_cached(&tree->root))) {
723 ref = rb_entry(node, struct prelim_ref, rbnode);
724 rb_erase_cached(node, &tree->root);
725
726 BUG_ON(ref->parent); /* should not be a direct ref */
727 BUG_ON(ref->key_for_search.type);
728 BUG_ON(!ref->wanted_disk_byte);
729
730 eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0,
731 ref->level - 1, NULL);
732 if (IS_ERR(eb)) {
733 free_pref(ref);
734 return PTR_ERR(eb);
735 } else if (!extent_buffer_uptodate(eb)) {
736 free_pref(ref);
737 free_extent_buffer(eb);
738 return -EIO;
739 }
740 btrfs_tree_read_lock(eb);
741 if (btrfs_header_level(eb) == 0)
742 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
743 else
744 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
745 btrfs_tree_read_unlock(eb);
746 free_extent_buffer(eb);
747 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
748 cond_resched();
749 }
750 return 0;
751 }
752
753 /*
754 * add all currently queued delayed refs from this head whose seq nr is
755 * smaller or equal that seq to the list
756 */
757 static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
758 struct btrfs_delayed_ref_head *head, u64 seq,
759 struct preftrees *preftrees, u64 *total_refs,
760 struct share_check *sc)
761 {
762 struct btrfs_delayed_ref_node *node;
763 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
764 struct btrfs_key key;
765 struct btrfs_key tmp_op_key;
766 struct rb_node *n;
767 int count;
768 int ret = 0;
769
770 if (extent_op && extent_op->update_key)
771 btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
772
773 spin_lock(&head->lock);
774 for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
775 node = rb_entry(n, struct btrfs_delayed_ref_node,
776 ref_node);
777 if (node->seq > seq)
778 continue;
779
780 switch (node->action) {
781 case BTRFS_ADD_DELAYED_EXTENT:
782 case BTRFS_UPDATE_DELAYED_HEAD:
783 WARN_ON(1);
784 continue;
785 case BTRFS_ADD_DELAYED_REF:
786 count = node->ref_mod;
787 break;
788 case BTRFS_DROP_DELAYED_REF:
789 count = node->ref_mod * -1;
790 break;
791 default:
792 BUG_ON(1);
793 }
794 *total_refs += count;
795 switch (node->type) {
796 case BTRFS_TREE_BLOCK_REF_KEY: {
797 /* NORMAL INDIRECT METADATA backref */
798 struct btrfs_delayed_tree_ref *ref;
799
800 ref = btrfs_delayed_node_to_tree_ref(node);
801 ret = add_indirect_ref(fs_info, preftrees, ref->root,
802 &tmp_op_key, ref->level + 1,
803 node->bytenr, count, sc,
804 GFP_ATOMIC);
805 break;
806 }
807 case BTRFS_SHARED_BLOCK_REF_KEY: {
808 /* SHARED DIRECT METADATA backref */
809 struct btrfs_delayed_tree_ref *ref;
810
811 ref = btrfs_delayed_node_to_tree_ref(node);
812
813 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
814 ref->parent, node->bytenr, count,
815 sc, GFP_ATOMIC);
816 break;
817 }
818 case BTRFS_EXTENT_DATA_REF_KEY: {
819 /* NORMAL INDIRECT DATA backref */
820 struct btrfs_delayed_data_ref *ref;
821 ref = btrfs_delayed_node_to_data_ref(node);
822
823 key.objectid = ref->objectid;
824 key.type = BTRFS_EXTENT_DATA_KEY;
825 key.offset = ref->offset;
826
827 /*
828 * Found a inum that doesn't match our known inum, we
829 * know it's shared.
830 */
831 if (sc && sc->inum && ref->objectid != sc->inum) {
832 ret = BACKREF_FOUND_SHARED;
833 goto out;
834 }
835
836 ret = add_indirect_ref(fs_info, preftrees, ref->root,
837 &key, 0, node->bytenr, count, sc,
838 GFP_ATOMIC);
839 break;
840 }
841 case BTRFS_SHARED_DATA_REF_KEY: {
842 /* SHARED DIRECT FULL backref */
843 struct btrfs_delayed_data_ref *ref;
844
845 ref = btrfs_delayed_node_to_data_ref(node);
846
847 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
848 node->bytenr, count, sc,
849 GFP_ATOMIC);
850 break;
851 }
852 default:
853 WARN_ON(1);
854 }
855 /*
856 * We must ignore BACKREF_FOUND_SHARED until all delayed
857 * refs have been checked.
858 */
859 if (ret && (ret != BACKREF_FOUND_SHARED))
860 break;
861 }
862 if (!ret)
863 ret = extent_is_shared(sc);
864 out:
865 spin_unlock(&head->lock);
866 return ret;
867 }
868
869 /*
870 * add all inline backrefs for bytenr to the list
871 *
872 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
873 */
874 static int add_inline_refs(const struct btrfs_fs_info *fs_info,
875 struct btrfs_path *path, u64 bytenr,
876 int *info_level, struct preftrees *preftrees,
877 u64 *total_refs, struct share_check *sc)
878 {
879 int ret = 0;
880 int slot;
881 struct extent_buffer *leaf;
882 struct btrfs_key key;
883 struct btrfs_key found_key;
884 unsigned long ptr;
885 unsigned long end;
886 struct btrfs_extent_item *ei;
887 u64 flags;
888 u64 item_size;
889
890 /*
891 * enumerate all inline refs
892 */
893 leaf = path->nodes[0];
894 slot = path->slots[0];
895
896 item_size = btrfs_item_size_nr(leaf, slot);
897 BUG_ON(item_size < sizeof(*ei));
898
899 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
900 flags = btrfs_extent_flags(leaf, ei);
901 *total_refs += btrfs_extent_refs(leaf, ei);
902 btrfs_item_key_to_cpu(leaf, &found_key, slot);
903
904 ptr = (unsigned long)(ei + 1);
905 end = (unsigned long)ei + item_size;
906
907 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
908 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
909 struct btrfs_tree_block_info *info;
910
911 info = (struct btrfs_tree_block_info *)ptr;
912 *info_level = btrfs_tree_block_level(leaf, info);
913 ptr += sizeof(struct btrfs_tree_block_info);
914 BUG_ON(ptr > end);
915 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
916 *info_level = found_key.offset;
917 } else {
918 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
919 }
920
921 while (ptr < end) {
922 struct btrfs_extent_inline_ref *iref;
923 u64 offset;
924 int type;
925
926 iref = (struct btrfs_extent_inline_ref *)ptr;
927 type = btrfs_get_extent_inline_ref_type(leaf, iref,
928 BTRFS_REF_TYPE_ANY);
929 if (type == BTRFS_REF_TYPE_INVALID)
930 return -EUCLEAN;
931
932 offset = btrfs_extent_inline_ref_offset(leaf, iref);
933
934 switch (type) {
935 case BTRFS_SHARED_BLOCK_REF_KEY:
936 ret = add_direct_ref(fs_info, preftrees,
937 *info_level + 1, offset,
938 bytenr, 1, NULL, GFP_NOFS);
939 break;
940 case BTRFS_SHARED_DATA_REF_KEY: {
941 struct btrfs_shared_data_ref *sdref;
942 int count;
943
944 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
945 count = btrfs_shared_data_ref_count(leaf, sdref);
946
947 ret = add_direct_ref(fs_info, preftrees, 0, offset,
948 bytenr, count, sc, GFP_NOFS);
949 break;
950 }
951 case BTRFS_TREE_BLOCK_REF_KEY:
952 ret = add_indirect_ref(fs_info, preftrees, offset,
953 NULL, *info_level + 1,
954 bytenr, 1, NULL, GFP_NOFS);
955 break;
956 case BTRFS_EXTENT_DATA_REF_KEY: {
957 struct btrfs_extent_data_ref *dref;
958 int count;
959 u64 root;
960
961 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
962 count = btrfs_extent_data_ref_count(leaf, dref);
963 key.objectid = btrfs_extent_data_ref_objectid(leaf,
964 dref);
965 key.type = BTRFS_EXTENT_DATA_KEY;
966 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
967
968 if (sc && sc->inum && key.objectid != sc->inum) {
969 ret = BACKREF_FOUND_SHARED;
970 break;
971 }
972
973 root = btrfs_extent_data_ref_root(leaf, dref);
974
975 ret = add_indirect_ref(fs_info, preftrees, root,
976 &key, 0, bytenr, count,
977 sc, GFP_NOFS);
978 break;
979 }
980 default:
981 WARN_ON(1);
982 }
983 if (ret)
984 return ret;
985 ptr += btrfs_extent_inline_ref_size(type);
986 }
987
988 return 0;
989 }
990
991 /*
992 * add all non-inline backrefs for bytenr to the list
993 *
994 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
995 */
996 static int add_keyed_refs(struct btrfs_fs_info *fs_info,
997 struct btrfs_path *path, u64 bytenr,
998 int info_level, struct preftrees *preftrees,
999 struct share_check *sc)
1000 {
1001 struct btrfs_root *extent_root = fs_info->extent_root;
1002 int ret;
1003 int slot;
1004 struct extent_buffer *leaf;
1005 struct btrfs_key key;
1006
1007 while (1) {
1008 ret = btrfs_next_item(extent_root, path);
1009 if (ret < 0)
1010 break;
1011 if (ret) {
1012 ret = 0;
1013 break;
1014 }
1015
1016 slot = path->slots[0];
1017 leaf = path->nodes[0];
1018 btrfs_item_key_to_cpu(leaf, &key, slot);
1019
1020 if (key.objectid != bytenr)
1021 break;
1022 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1023 continue;
1024 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1025 break;
1026
1027 switch (key.type) {
1028 case BTRFS_SHARED_BLOCK_REF_KEY:
1029 /* SHARED DIRECT METADATA backref */
1030 ret = add_direct_ref(fs_info, preftrees,
1031 info_level + 1, key.offset,
1032 bytenr, 1, NULL, GFP_NOFS);
1033 break;
1034 case BTRFS_SHARED_DATA_REF_KEY: {
1035 /* SHARED DIRECT FULL backref */
1036 struct btrfs_shared_data_ref *sdref;
1037 int count;
1038
1039 sdref = btrfs_item_ptr(leaf, slot,
1040 struct btrfs_shared_data_ref);
1041 count = btrfs_shared_data_ref_count(leaf, sdref);
1042 ret = add_direct_ref(fs_info, preftrees, 0,
1043 key.offset, bytenr, count,
1044 sc, GFP_NOFS);
1045 break;
1046 }
1047 case BTRFS_TREE_BLOCK_REF_KEY:
1048 /* NORMAL INDIRECT METADATA backref */
1049 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1050 NULL, info_level + 1, bytenr,
1051 1, NULL, GFP_NOFS);
1052 break;
1053 case BTRFS_EXTENT_DATA_REF_KEY: {
1054 /* NORMAL INDIRECT DATA backref */
1055 struct btrfs_extent_data_ref *dref;
1056 int count;
1057 u64 root;
1058
1059 dref = btrfs_item_ptr(leaf, slot,
1060 struct btrfs_extent_data_ref);
1061 count = btrfs_extent_data_ref_count(leaf, dref);
1062 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1063 dref);
1064 key.type = BTRFS_EXTENT_DATA_KEY;
1065 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1066
1067 if (sc && sc->inum && key.objectid != sc->inum) {
1068 ret = BACKREF_FOUND_SHARED;
1069 break;
1070 }
1071
1072 root = btrfs_extent_data_ref_root(leaf, dref);
1073 ret = add_indirect_ref(fs_info, preftrees, root,
1074 &key, 0, bytenr, count,
1075 sc, GFP_NOFS);
1076 break;
1077 }
1078 default:
1079 WARN_ON(1);
1080 }
1081 if (ret)
1082 return ret;
1083
1084 }
1085
1086 return ret;
1087 }
1088
1089 /*
1090 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1091 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1092 * indirect refs to their parent bytenr.
1093 * When roots are found, they're added to the roots list
1094 *
1095 * If time_seq is set to SEQ_LAST, it will not search delayed_refs, and behave
1096 * much like trans == NULL case, the difference only lies in it will not
1097 * commit root.
1098 * The special case is for qgroup to search roots in commit_transaction().
1099 *
1100 * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a
1101 * shared extent is detected.
1102 *
1103 * Otherwise this returns 0 for success and <0 for an error.
1104 *
1105 * If ignore_offset is set to false, only extent refs whose offsets match
1106 * extent_item_pos are returned. If true, every extent ref is returned
1107 * and extent_item_pos is ignored.
1108 *
1109 * FIXME some caching might speed things up
1110 */
1111 static int find_parent_nodes(struct btrfs_trans_handle *trans,
1112 struct btrfs_fs_info *fs_info, u64 bytenr,
1113 u64 time_seq, struct ulist *refs,
1114 struct ulist *roots, const u64 *extent_item_pos,
1115 struct share_check *sc, bool ignore_offset)
1116 {
1117 struct btrfs_key key;
1118 struct btrfs_path *path;
1119 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1120 struct btrfs_delayed_ref_head *head;
1121 int info_level = 0;
1122 int ret;
1123 struct prelim_ref *ref;
1124 struct rb_node *node;
1125 struct extent_inode_elem *eie = NULL;
1126 /* total of both direct AND indirect refs! */
1127 u64 total_refs = 0;
1128 struct preftrees preftrees = {
1129 .direct = PREFTREE_INIT,
1130 .indirect = PREFTREE_INIT,
1131 .indirect_missing_keys = PREFTREE_INIT
1132 };
1133
1134 key.objectid = bytenr;
1135 key.offset = (u64)-1;
1136 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1137 key.type = BTRFS_METADATA_ITEM_KEY;
1138 else
1139 key.type = BTRFS_EXTENT_ITEM_KEY;
1140
1141 path = btrfs_alloc_path();
1142 if (!path)
1143 return -ENOMEM;
1144 if (!trans) {
1145 path->search_commit_root = 1;
1146 path->skip_locking = 1;
1147 }
1148
1149 if (time_seq == SEQ_LAST)
1150 path->skip_locking = 1;
1151
1152 /*
1153 * grab both a lock on the path and a lock on the delayed ref head.
1154 * We need both to get a consistent picture of how the refs look
1155 * at a specified point in time
1156 */
1157 again:
1158 head = NULL;
1159
1160 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
1161 if (ret < 0)
1162 goto out;
1163 BUG_ON(ret == 0);
1164
1165 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1166 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1167 time_seq != SEQ_LAST) {
1168 #else
1169 if (trans && time_seq != SEQ_LAST) {
1170 #endif
1171 /*
1172 * look if there are updates for this ref queued and lock the
1173 * head
1174 */
1175 delayed_refs = &trans->transaction->delayed_refs;
1176 spin_lock(&delayed_refs->lock);
1177 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
1178 if (head) {
1179 if (!mutex_trylock(&head->mutex)) {
1180 refcount_inc(&head->refs);
1181 spin_unlock(&delayed_refs->lock);
1182
1183 btrfs_release_path(path);
1184
1185 /*
1186 * Mutex was contended, block until it's
1187 * released and try again
1188 */
1189 mutex_lock(&head->mutex);
1190 mutex_unlock(&head->mutex);
1191 btrfs_put_delayed_ref_head(head);
1192 goto again;
1193 }
1194 spin_unlock(&delayed_refs->lock);
1195 ret = add_delayed_refs(fs_info, head, time_seq,
1196 &preftrees, &total_refs, sc);
1197 mutex_unlock(&head->mutex);
1198 if (ret)
1199 goto out;
1200 } else {
1201 spin_unlock(&delayed_refs->lock);
1202 }
1203 }
1204
1205 if (path->slots[0]) {
1206 struct extent_buffer *leaf;
1207 int slot;
1208
1209 path->slots[0]--;
1210 leaf = path->nodes[0];
1211 slot = path->slots[0];
1212 btrfs_item_key_to_cpu(leaf, &key, slot);
1213 if (key.objectid == bytenr &&
1214 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1215 key.type == BTRFS_METADATA_ITEM_KEY)) {
1216 ret = add_inline_refs(fs_info, path, bytenr,
1217 &info_level, &preftrees,
1218 &total_refs, sc);
1219 if (ret)
1220 goto out;
1221 ret = add_keyed_refs(fs_info, path, bytenr, info_level,
1222 &preftrees, sc);
1223 if (ret)
1224 goto out;
1225 }
1226 }
1227
1228 btrfs_release_path(path);
1229
1230 ret = add_missing_keys(fs_info, &preftrees);
1231 if (ret)
1232 goto out;
1233
1234 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root));
1235
1236 ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees,
1237 extent_item_pos, total_refs, sc, ignore_offset);
1238 if (ret)
1239 goto out;
1240
1241 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root));
1242
1243 /*
1244 * This walks the tree of merged and resolved refs. Tree blocks are
1245 * read in as needed. Unique entries are added to the ulist, and
1246 * the list of found roots is updated.
1247 *
1248 * We release the entire tree in one go before returning.
1249 */
1250 node = rb_first_cached(&preftrees.direct.root);
1251 while (node) {
1252 ref = rb_entry(node, struct prelim_ref, rbnode);
1253 node = rb_next(&ref->rbnode);
1254 /*
1255 * ref->count < 0 can happen here if there are delayed
1256 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1257 * prelim_ref_insert() relies on this when merging
1258 * identical refs to keep the overall count correct.
1259 * prelim_ref_insert() will merge only those refs
1260 * which compare identically. Any refs having
1261 * e.g. different offsets would not be merged,
1262 * and would retain their original ref->count < 0.
1263 */
1264 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1265 if (sc && sc->root_objectid &&
1266 ref->root_id != sc->root_objectid) {
1267 ret = BACKREF_FOUND_SHARED;
1268 goto out;
1269 }
1270
1271 /* no parent == root of tree */
1272 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1273 if (ret < 0)
1274 goto out;
1275 }
1276 if (ref->count && ref->parent) {
1277 if (extent_item_pos && !ref->inode_list &&
1278 ref->level == 0) {
1279 struct extent_buffer *eb;
1280
1281 eb = read_tree_block(fs_info, ref->parent, 0,
1282 ref->level, NULL);
1283 if (IS_ERR(eb)) {
1284 ret = PTR_ERR(eb);
1285 goto out;
1286 } else if (!extent_buffer_uptodate(eb)) {
1287 free_extent_buffer(eb);
1288 ret = -EIO;
1289 goto out;
1290 }
1291 btrfs_tree_read_lock(eb);
1292 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1293 ret = find_extent_in_eb(eb, bytenr,
1294 *extent_item_pos, &eie, ignore_offset);
1295 btrfs_tree_read_unlock_blocking(eb);
1296 free_extent_buffer(eb);
1297 if (ret < 0)
1298 goto out;
1299 ref->inode_list = eie;
1300 }
1301 ret = ulist_add_merge_ptr(refs, ref->parent,
1302 ref->inode_list,
1303 (void **)&eie, GFP_NOFS);
1304 if (ret < 0)
1305 goto out;
1306 if (!ret && extent_item_pos) {
1307 /*
1308 * we've recorded that parent, so we must extend
1309 * its inode list here
1310 */
1311 BUG_ON(!eie);
1312 while (eie->next)
1313 eie = eie->next;
1314 eie->next = ref->inode_list;
1315 }
1316 eie = NULL;
1317 }
1318 cond_resched();
1319 }
1320
1321 out:
1322 btrfs_free_path(path);
1323
1324 prelim_release(&preftrees.direct);
1325 prelim_release(&preftrees.indirect);
1326 prelim_release(&preftrees.indirect_missing_keys);
1327
1328 if (ret < 0)
1329 free_inode_elem_list(eie);
1330 return ret;
1331 }
1332
1333 static void free_leaf_list(struct ulist *blocks)
1334 {
1335 struct ulist_node *node = NULL;
1336 struct extent_inode_elem *eie;
1337 struct ulist_iterator uiter;
1338
1339 ULIST_ITER_INIT(&uiter);
1340 while ((node = ulist_next(blocks, &uiter))) {
1341 if (!node->aux)
1342 continue;
1343 eie = unode_aux_to_inode_list(node);
1344 free_inode_elem_list(eie);
1345 node->aux = 0;
1346 }
1347
1348 ulist_free(blocks);
1349 }
1350
1351 /*
1352 * Finds all leafs with a reference to the specified combination of bytenr and
1353 * offset. key_list_head will point to a list of corresponding keys (caller must
1354 * free each list element). The leafs will be stored in the leafs ulist, which
1355 * must be freed with ulist_free.
1356 *
1357 * returns 0 on success, <0 on error
1358 */
1359 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1360 struct btrfs_fs_info *fs_info, u64 bytenr,
1361 u64 time_seq, struct ulist **leafs,
1362 const u64 *extent_item_pos, bool ignore_offset)
1363 {
1364 int ret;
1365
1366 *leafs = ulist_alloc(GFP_NOFS);
1367 if (!*leafs)
1368 return -ENOMEM;
1369
1370 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1371 *leafs, NULL, extent_item_pos, NULL, ignore_offset);
1372 if (ret < 0 && ret != -ENOENT) {
1373 free_leaf_list(*leafs);
1374 return ret;
1375 }
1376
1377 return 0;
1378 }
1379
1380 /*
1381 * walk all backrefs for a given extent to find all roots that reference this
1382 * extent. Walking a backref means finding all extents that reference this
1383 * extent and in turn walk the backrefs of those, too. Naturally this is a
1384 * recursive process, but here it is implemented in an iterative fashion: We
1385 * find all referencing extents for the extent in question and put them on a
1386 * list. In turn, we find all referencing extents for those, further appending
1387 * to the list. The way we iterate the list allows adding more elements after
1388 * the current while iterating. The process stops when we reach the end of the
1389 * list. Found roots are added to the roots list.
1390 *
1391 * returns 0 on success, < 0 on error.
1392 */
1393 static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
1394 struct btrfs_fs_info *fs_info, u64 bytenr,
1395 u64 time_seq, struct ulist **roots,
1396 bool ignore_offset)
1397 {
1398 struct ulist *tmp;
1399 struct ulist_node *node = NULL;
1400 struct ulist_iterator uiter;
1401 int ret;
1402
1403 tmp = ulist_alloc(GFP_NOFS);
1404 if (!tmp)
1405 return -ENOMEM;
1406 *roots = ulist_alloc(GFP_NOFS);
1407 if (!*roots) {
1408 ulist_free(tmp);
1409 return -ENOMEM;
1410 }
1411
1412 ULIST_ITER_INIT(&uiter);
1413 while (1) {
1414 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1415 tmp, *roots, NULL, NULL, ignore_offset);
1416 if (ret < 0 && ret != -ENOENT) {
1417 ulist_free(tmp);
1418 ulist_free(*roots);
1419 return ret;
1420 }
1421 node = ulist_next(tmp, &uiter);
1422 if (!node)
1423 break;
1424 bytenr = node->val;
1425 cond_resched();
1426 }
1427
1428 ulist_free(tmp);
1429 return 0;
1430 }
1431
1432 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1433 struct btrfs_fs_info *fs_info, u64 bytenr,
1434 u64 time_seq, struct ulist **roots,
1435 bool ignore_offset)
1436 {
1437 int ret;
1438
1439 if (!trans)
1440 down_read(&fs_info->commit_root_sem);
1441 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr,
1442 time_seq, roots, ignore_offset);
1443 if (!trans)
1444 up_read(&fs_info->commit_root_sem);
1445 return ret;
1446 }
1447
1448 /**
1449 * btrfs_check_shared - tell us whether an extent is shared
1450 *
1451 * btrfs_check_shared uses the backref walking code but will short
1452 * circuit as soon as it finds a root or inode that doesn't match the
1453 * one passed in. This provides a significant performance benefit for
1454 * callers (such as fiemap) which want to know whether the extent is
1455 * shared but do not need a ref count.
1456 *
1457 * This attempts to allocate a transaction in order to account for
1458 * delayed refs, but continues on even when the alloc fails.
1459 *
1460 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1461 */
1462 int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
1463 {
1464 struct btrfs_fs_info *fs_info = root->fs_info;
1465 struct btrfs_trans_handle *trans;
1466 struct ulist *tmp = NULL;
1467 struct ulist *roots = NULL;
1468 struct ulist_iterator uiter;
1469 struct ulist_node *node;
1470 struct seq_list elem = SEQ_LIST_INIT(elem);
1471 int ret = 0;
1472 struct share_check shared = {
1473 .root_objectid = root->root_key.objectid,
1474 .inum = inum,
1475 .share_count = 0,
1476 };
1477
1478 tmp = ulist_alloc(GFP_NOFS);
1479 roots = ulist_alloc(GFP_NOFS);
1480 if (!tmp || !roots) {
1481 ulist_free(tmp);
1482 ulist_free(roots);
1483 return -ENOMEM;
1484 }
1485
1486 trans = btrfs_join_transaction(root);
1487 if (IS_ERR(trans)) {
1488 trans = NULL;
1489 down_read(&fs_info->commit_root_sem);
1490 } else {
1491 btrfs_get_tree_mod_seq(fs_info, &elem);
1492 }
1493
1494 ULIST_ITER_INIT(&uiter);
1495 while (1) {
1496 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1497 roots, NULL, &shared, false);
1498 if (ret == BACKREF_FOUND_SHARED) {
1499 /* this is the only condition under which we return 1 */
1500 ret = 1;
1501 break;
1502 }
1503 if (ret < 0 && ret != -ENOENT)
1504 break;
1505 ret = 0;
1506 node = ulist_next(tmp, &uiter);
1507 if (!node)
1508 break;
1509 bytenr = node->val;
1510 shared.share_count = 0;
1511 cond_resched();
1512 }
1513
1514 if (trans) {
1515 btrfs_put_tree_mod_seq(fs_info, &elem);
1516 btrfs_end_transaction(trans);
1517 } else {
1518 up_read(&fs_info->commit_root_sem);
1519 }
1520 ulist_free(tmp);
1521 ulist_free(roots);
1522 return ret;
1523 }
1524
1525 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1526 u64 start_off, struct btrfs_path *path,
1527 struct btrfs_inode_extref **ret_extref,
1528 u64 *found_off)
1529 {
1530 int ret, slot;
1531 struct btrfs_key key;
1532 struct btrfs_key found_key;
1533 struct btrfs_inode_extref *extref;
1534 const struct extent_buffer *leaf;
1535 unsigned long ptr;
1536
1537 key.objectid = inode_objectid;
1538 key.type = BTRFS_INODE_EXTREF_KEY;
1539 key.offset = start_off;
1540
1541 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1542 if (ret < 0)
1543 return ret;
1544
1545 while (1) {
1546 leaf = path->nodes[0];
1547 slot = path->slots[0];
1548 if (slot >= btrfs_header_nritems(leaf)) {
1549 /*
1550 * If the item at offset is not found,
1551 * btrfs_search_slot will point us to the slot
1552 * where it should be inserted. In our case
1553 * that will be the slot directly before the
1554 * next INODE_REF_KEY_V2 item. In the case
1555 * that we're pointing to the last slot in a
1556 * leaf, we must move one leaf over.
1557 */
1558 ret = btrfs_next_leaf(root, path);
1559 if (ret) {
1560 if (ret >= 1)
1561 ret = -ENOENT;
1562 break;
1563 }
1564 continue;
1565 }
1566
1567 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1568
1569 /*
1570 * Check that we're still looking at an extended ref key for
1571 * this particular objectid. If we have different
1572 * objectid or type then there are no more to be found
1573 * in the tree and we can exit.
1574 */
1575 ret = -ENOENT;
1576 if (found_key.objectid != inode_objectid)
1577 break;
1578 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1579 break;
1580
1581 ret = 0;
1582 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1583 extref = (struct btrfs_inode_extref *)ptr;
1584 *ret_extref = extref;
1585 if (found_off)
1586 *found_off = found_key.offset;
1587 break;
1588 }
1589
1590 return ret;
1591 }
1592
1593 /*
1594 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1595 * Elements of the path are separated by '/' and the path is guaranteed to be
1596 * 0-terminated. the path is only given within the current file system.
1597 * Therefore, it never starts with a '/'. the caller is responsible to provide
1598 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1599 * the start point of the resulting string is returned. this pointer is within
1600 * dest, normally.
1601 * in case the path buffer would overflow, the pointer is decremented further
1602 * as if output was written to the buffer, though no more output is actually
1603 * generated. that way, the caller can determine how much space would be
1604 * required for the path to fit into the buffer. in that case, the returned
1605 * value will be smaller than dest. callers must check this!
1606 */
1607 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1608 u32 name_len, unsigned long name_off,
1609 struct extent_buffer *eb_in, u64 parent,
1610 char *dest, u32 size)
1611 {
1612 int slot;
1613 u64 next_inum;
1614 int ret;
1615 s64 bytes_left = ((s64)size) - 1;
1616 struct extent_buffer *eb = eb_in;
1617 struct btrfs_key found_key;
1618 int leave_spinning = path->leave_spinning;
1619 struct btrfs_inode_ref *iref;
1620
1621 if (bytes_left >= 0)
1622 dest[bytes_left] = '\0';
1623
1624 path->leave_spinning = 1;
1625 while (1) {
1626 bytes_left -= name_len;
1627 if (bytes_left >= 0)
1628 read_extent_buffer(eb, dest + bytes_left,
1629 name_off, name_len);
1630 if (eb != eb_in) {
1631 if (!path->skip_locking)
1632 btrfs_tree_read_unlock_blocking(eb);
1633 free_extent_buffer(eb);
1634 }
1635 ret = btrfs_find_item(fs_root, path, parent, 0,
1636 BTRFS_INODE_REF_KEY, &found_key);
1637 if (ret > 0)
1638 ret = -ENOENT;
1639 if (ret)
1640 break;
1641
1642 next_inum = found_key.offset;
1643
1644 /* regular exit ahead */
1645 if (parent == next_inum)
1646 break;
1647
1648 slot = path->slots[0];
1649 eb = path->nodes[0];
1650 /* make sure we can use eb after releasing the path */
1651 if (eb != eb_in) {
1652 if (!path->skip_locking)
1653 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1654 path->nodes[0] = NULL;
1655 path->locks[0] = 0;
1656 }
1657 btrfs_release_path(path);
1658 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1659
1660 name_len = btrfs_inode_ref_name_len(eb, iref);
1661 name_off = (unsigned long)(iref + 1);
1662
1663 parent = next_inum;
1664 --bytes_left;
1665 if (bytes_left >= 0)
1666 dest[bytes_left] = '/';
1667 }
1668
1669 btrfs_release_path(path);
1670 path->leave_spinning = leave_spinning;
1671
1672 if (ret)
1673 return ERR_PTR(ret);
1674
1675 return dest + bytes_left;
1676 }
1677
1678 /*
1679 * this makes the path point to (logical EXTENT_ITEM *)
1680 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1681 * tree blocks and <0 on error.
1682 */
1683 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1684 struct btrfs_path *path, struct btrfs_key *found_key,
1685 u64 *flags_ret)
1686 {
1687 int ret;
1688 u64 flags;
1689 u64 size = 0;
1690 u32 item_size;
1691 const struct extent_buffer *eb;
1692 struct btrfs_extent_item *ei;
1693 struct btrfs_key key;
1694
1695 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1696 key.type = BTRFS_METADATA_ITEM_KEY;
1697 else
1698 key.type = BTRFS_EXTENT_ITEM_KEY;
1699 key.objectid = logical;
1700 key.offset = (u64)-1;
1701
1702 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1703 if (ret < 0)
1704 return ret;
1705
1706 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1707 if (ret) {
1708 if (ret > 0)
1709 ret = -ENOENT;
1710 return ret;
1711 }
1712 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1713 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1714 size = fs_info->nodesize;
1715 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1716 size = found_key->offset;
1717
1718 if (found_key->objectid > logical ||
1719 found_key->objectid + size <= logical) {
1720 btrfs_debug(fs_info,
1721 "logical %llu is not within any extent", logical);
1722 return -ENOENT;
1723 }
1724
1725 eb = path->nodes[0];
1726 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1727 BUG_ON(item_size < sizeof(*ei));
1728
1729 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1730 flags = btrfs_extent_flags(eb, ei);
1731
1732 btrfs_debug(fs_info,
1733 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1734 logical, logical - found_key->objectid, found_key->objectid,
1735 found_key->offset, flags, item_size);
1736
1737 WARN_ON(!flags_ret);
1738 if (flags_ret) {
1739 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1740 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1741 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1742 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1743 else
1744 BUG_ON(1);
1745 return 0;
1746 }
1747
1748 return -EIO;
1749 }
1750
1751 /*
1752 * helper function to iterate extent inline refs. ptr must point to a 0 value
1753 * for the first call and may be modified. it is used to track state.
1754 * if more refs exist, 0 is returned and the next call to
1755 * get_extent_inline_ref must pass the modified ptr parameter to get the
1756 * next ref. after the last ref was processed, 1 is returned.
1757 * returns <0 on error
1758 */
1759 static int get_extent_inline_ref(unsigned long *ptr,
1760 const struct extent_buffer *eb,
1761 const struct btrfs_key *key,
1762 const struct btrfs_extent_item *ei,
1763 u32 item_size,
1764 struct btrfs_extent_inline_ref **out_eiref,
1765 int *out_type)
1766 {
1767 unsigned long end;
1768 u64 flags;
1769 struct btrfs_tree_block_info *info;
1770
1771 if (!*ptr) {
1772 /* first call */
1773 flags = btrfs_extent_flags(eb, ei);
1774 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1775 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1776 /* a skinny metadata extent */
1777 *out_eiref =
1778 (struct btrfs_extent_inline_ref *)(ei + 1);
1779 } else {
1780 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1781 info = (struct btrfs_tree_block_info *)(ei + 1);
1782 *out_eiref =
1783 (struct btrfs_extent_inline_ref *)(info + 1);
1784 }
1785 } else {
1786 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1787 }
1788 *ptr = (unsigned long)*out_eiref;
1789 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1790 return -ENOENT;
1791 }
1792
1793 end = (unsigned long)ei + item_size;
1794 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1795 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
1796 BTRFS_REF_TYPE_ANY);
1797 if (*out_type == BTRFS_REF_TYPE_INVALID)
1798 return -EUCLEAN;
1799
1800 *ptr += btrfs_extent_inline_ref_size(*out_type);
1801 WARN_ON(*ptr > end);
1802 if (*ptr == end)
1803 return 1; /* last */
1804
1805 return 0;
1806 }
1807
1808 /*
1809 * reads the tree block backref for an extent. tree level and root are returned
1810 * through out_level and out_root. ptr must point to a 0 value for the first
1811 * call and may be modified (see get_extent_inline_ref comment).
1812 * returns 0 if data was provided, 1 if there was no more data to provide or
1813 * <0 on error.
1814 */
1815 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1816 struct btrfs_key *key, struct btrfs_extent_item *ei,
1817 u32 item_size, u64 *out_root, u8 *out_level)
1818 {
1819 int ret;
1820 int type;
1821 struct btrfs_extent_inline_ref *eiref;
1822
1823 if (*ptr == (unsigned long)-1)
1824 return 1;
1825
1826 while (1) {
1827 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
1828 &eiref, &type);
1829 if (ret < 0)
1830 return ret;
1831
1832 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1833 type == BTRFS_SHARED_BLOCK_REF_KEY)
1834 break;
1835
1836 if (ret == 1)
1837 return 1;
1838 }
1839
1840 /* we can treat both ref types equally here */
1841 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1842
1843 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1844 struct btrfs_tree_block_info *info;
1845
1846 info = (struct btrfs_tree_block_info *)(ei + 1);
1847 *out_level = btrfs_tree_block_level(eb, info);
1848 } else {
1849 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1850 *out_level = (u8)key->offset;
1851 }
1852
1853 if (ret == 1)
1854 *ptr = (unsigned long)-1;
1855
1856 return 0;
1857 }
1858
1859 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1860 struct extent_inode_elem *inode_list,
1861 u64 root, u64 extent_item_objectid,
1862 iterate_extent_inodes_t *iterate, void *ctx)
1863 {
1864 struct extent_inode_elem *eie;
1865 int ret = 0;
1866
1867 for (eie = inode_list; eie; eie = eie->next) {
1868 btrfs_debug(fs_info,
1869 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1870 extent_item_objectid, eie->inum,
1871 eie->offset, root);
1872 ret = iterate(eie->inum, eie->offset, root, ctx);
1873 if (ret) {
1874 btrfs_debug(fs_info,
1875 "stopping iteration for %llu due to ret=%d",
1876 extent_item_objectid, ret);
1877 break;
1878 }
1879 }
1880
1881 return ret;
1882 }
1883
1884 /*
1885 * calls iterate() for every inode that references the extent identified by
1886 * the given parameters.
1887 * when the iterator function returns a non-zero value, iteration stops.
1888 */
1889 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1890 u64 extent_item_objectid, u64 extent_item_pos,
1891 int search_commit_root,
1892 iterate_extent_inodes_t *iterate, void *ctx,
1893 bool ignore_offset)
1894 {
1895 int ret;
1896 struct btrfs_trans_handle *trans = NULL;
1897 struct ulist *refs = NULL;
1898 struct ulist *roots = NULL;
1899 struct ulist_node *ref_node = NULL;
1900 struct ulist_node *root_node = NULL;
1901 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
1902 struct ulist_iterator ref_uiter;
1903 struct ulist_iterator root_uiter;
1904
1905 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
1906 extent_item_objectid);
1907
1908 if (!search_commit_root) {
1909 trans = btrfs_join_transaction(fs_info->extent_root);
1910 if (IS_ERR(trans))
1911 return PTR_ERR(trans);
1912 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1913 } else {
1914 down_read(&fs_info->commit_root_sem);
1915 }
1916
1917 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1918 tree_mod_seq_elem.seq, &refs,
1919 &extent_item_pos, ignore_offset);
1920 if (ret)
1921 goto out;
1922
1923 ULIST_ITER_INIT(&ref_uiter);
1924 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1925 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val,
1926 tree_mod_seq_elem.seq, &roots,
1927 ignore_offset);
1928 if (ret)
1929 break;
1930 ULIST_ITER_INIT(&root_uiter);
1931 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1932 btrfs_debug(fs_info,
1933 "root %llu references leaf %llu, data list %#llx",
1934 root_node->val, ref_node->val,
1935 ref_node->aux);
1936 ret = iterate_leaf_refs(fs_info,
1937 (struct extent_inode_elem *)
1938 (uintptr_t)ref_node->aux,
1939 root_node->val,
1940 extent_item_objectid,
1941 iterate, ctx);
1942 }
1943 ulist_free(roots);
1944 }
1945
1946 free_leaf_list(refs);
1947 out:
1948 if (!search_commit_root) {
1949 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1950 btrfs_end_transaction(trans);
1951 } else {
1952 up_read(&fs_info->commit_root_sem);
1953 }
1954
1955 return ret;
1956 }
1957
1958 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1959 struct btrfs_path *path,
1960 iterate_extent_inodes_t *iterate, void *ctx,
1961 bool ignore_offset)
1962 {
1963 int ret;
1964 u64 extent_item_pos;
1965 u64 flags = 0;
1966 struct btrfs_key found_key;
1967 int search_commit_root = path->search_commit_root;
1968
1969 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1970 btrfs_release_path(path);
1971 if (ret < 0)
1972 return ret;
1973 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1974 return -EINVAL;
1975
1976 extent_item_pos = logical - found_key.objectid;
1977 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1978 extent_item_pos, search_commit_root,
1979 iterate, ctx, ignore_offset);
1980
1981 return ret;
1982 }
1983
1984 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1985 struct extent_buffer *eb, void *ctx);
1986
1987 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1988 struct btrfs_path *path,
1989 iterate_irefs_t *iterate, void *ctx)
1990 {
1991 int ret = 0;
1992 int slot;
1993 u32 cur;
1994 u32 len;
1995 u32 name_len;
1996 u64 parent = 0;
1997 int found = 0;
1998 struct extent_buffer *eb;
1999 struct btrfs_item *item;
2000 struct btrfs_inode_ref *iref;
2001 struct btrfs_key found_key;
2002
2003 while (!ret) {
2004 ret = btrfs_find_item(fs_root, path, inum,
2005 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2006 &found_key);
2007
2008 if (ret < 0)
2009 break;
2010 if (ret) {
2011 ret = found ? 0 : -ENOENT;
2012 break;
2013 }
2014 ++found;
2015
2016 parent = found_key.offset;
2017 slot = path->slots[0];
2018 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2019 if (!eb) {
2020 ret = -ENOMEM;
2021 break;
2022 }
2023 extent_buffer_get(eb);
2024 btrfs_tree_read_lock(eb);
2025 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2026 btrfs_release_path(path);
2027
2028 item = btrfs_item_nr(slot);
2029 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2030
2031 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
2032 name_len = btrfs_inode_ref_name_len(eb, iref);
2033 /* path must be released before calling iterate()! */
2034 btrfs_debug(fs_root->fs_info,
2035 "following ref at offset %u for inode %llu in tree %llu",
2036 cur, found_key.objectid,
2037 fs_root->root_key.objectid);
2038 ret = iterate(parent, name_len,
2039 (unsigned long)(iref + 1), eb, ctx);
2040 if (ret)
2041 break;
2042 len = sizeof(*iref) + name_len;
2043 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2044 }
2045 btrfs_tree_read_unlock_blocking(eb);
2046 free_extent_buffer(eb);
2047 }
2048
2049 btrfs_release_path(path);
2050
2051 return ret;
2052 }
2053
2054 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
2055 struct btrfs_path *path,
2056 iterate_irefs_t *iterate, void *ctx)
2057 {
2058 int ret;
2059 int slot;
2060 u64 offset = 0;
2061 u64 parent;
2062 int found = 0;
2063 struct extent_buffer *eb;
2064 struct btrfs_inode_extref *extref;
2065 u32 item_size;
2066 u32 cur_offset;
2067 unsigned long ptr;
2068
2069 while (1) {
2070 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2071 &offset);
2072 if (ret < 0)
2073 break;
2074 if (ret) {
2075 ret = found ? 0 : -ENOENT;
2076 break;
2077 }
2078 ++found;
2079
2080 slot = path->slots[0];
2081 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2082 if (!eb) {
2083 ret = -ENOMEM;
2084 break;
2085 }
2086 extent_buffer_get(eb);
2087
2088 btrfs_tree_read_lock(eb);
2089 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2090 btrfs_release_path(path);
2091
2092 item_size = btrfs_item_size_nr(eb, slot);
2093 ptr = btrfs_item_ptr_offset(eb, slot);
2094 cur_offset = 0;
2095
2096 while (cur_offset < item_size) {
2097 u32 name_len;
2098
2099 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2100 parent = btrfs_inode_extref_parent(eb, extref);
2101 name_len = btrfs_inode_extref_name_len(eb, extref);
2102 ret = iterate(parent, name_len,
2103 (unsigned long)&extref->name, eb, ctx);
2104 if (ret)
2105 break;
2106
2107 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2108 cur_offset += sizeof(*extref);
2109 }
2110 btrfs_tree_read_unlock_blocking(eb);
2111 free_extent_buffer(eb);
2112
2113 offset++;
2114 }
2115
2116 btrfs_release_path(path);
2117
2118 return ret;
2119 }
2120
2121 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
2122 struct btrfs_path *path, iterate_irefs_t *iterate,
2123 void *ctx)
2124 {
2125 int ret;
2126 int found_refs = 0;
2127
2128 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
2129 if (!ret)
2130 ++found_refs;
2131 else if (ret != -ENOENT)
2132 return ret;
2133
2134 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
2135 if (ret == -ENOENT && found_refs)
2136 return 0;
2137
2138 return ret;
2139 }
2140
2141 /*
2142 * returns 0 if the path could be dumped (probably truncated)
2143 * returns <0 in case of an error
2144 */
2145 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2146 struct extent_buffer *eb, void *ctx)
2147 {
2148 struct inode_fs_paths *ipath = ctx;
2149 char *fspath;
2150 char *fspath_min;
2151 int i = ipath->fspath->elem_cnt;
2152 const int s_ptr = sizeof(char *);
2153 u32 bytes_left;
2154
2155 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2156 ipath->fspath->bytes_left - s_ptr : 0;
2157
2158 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2159 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2160 name_off, eb, inum, fspath_min, bytes_left);
2161 if (IS_ERR(fspath))
2162 return PTR_ERR(fspath);
2163
2164 if (fspath > fspath_min) {
2165 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2166 ++ipath->fspath->elem_cnt;
2167 ipath->fspath->bytes_left = fspath - fspath_min;
2168 } else {
2169 ++ipath->fspath->elem_missed;
2170 ipath->fspath->bytes_missing += fspath_min - fspath;
2171 ipath->fspath->bytes_left = 0;
2172 }
2173
2174 return 0;
2175 }
2176
2177 /*
2178 * this dumps all file system paths to the inode into the ipath struct, provided
2179 * is has been created large enough. each path is zero-terminated and accessed
2180 * from ipath->fspath->val[i].
2181 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2182 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2183 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2184 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2185 * have been needed to return all paths.
2186 */
2187 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2188 {
2189 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
2190 inode_to_path, ipath);
2191 }
2192
2193 struct btrfs_data_container *init_data_container(u32 total_bytes)
2194 {
2195 struct btrfs_data_container *data;
2196 size_t alloc_bytes;
2197
2198 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2199 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2200 if (!data)
2201 return ERR_PTR(-ENOMEM);
2202
2203 if (total_bytes >= sizeof(*data)) {
2204 data->bytes_left = total_bytes - sizeof(*data);
2205 data->bytes_missing = 0;
2206 } else {
2207 data->bytes_missing = sizeof(*data) - total_bytes;
2208 data->bytes_left = 0;
2209 }
2210
2211 data->elem_cnt = 0;
2212 data->elem_missed = 0;
2213
2214 return data;
2215 }
2216
2217 /*
2218 * allocates space to return multiple file system paths for an inode.
2219 * total_bytes to allocate are passed, note that space usable for actual path
2220 * information will be total_bytes - sizeof(struct inode_fs_paths).
2221 * the returned pointer must be freed with free_ipath() in the end.
2222 */
2223 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2224 struct btrfs_path *path)
2225 {
2226 struct inode_fs_paths *ifp;
2227 struct btrfs_data_container *fspath;
2228
2229 fspath = init_data_container(total_bytes);
2230 if (IS_ERR(fspath))
2231 return ERR_CAST(fspath);
2232
2233 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2234 if (!ifp) {
2235 kvfree(fspath);
2236 return ERR_PTR(-ENOMEM);
2237 }
2238
2239 ifp->btrfs_path = path;
2240 ifp->fspath = fspath;
2241 ifp->fs_root = fs_root;
2242
2243 return ifp;
2244 }
2245
2246 void free_ipath(struct inode_fs_paths *ipath)
2247 {
2248 if (!ipath)
2249 return;
2250 kvfree(ipath->fspath);
2251 kfree(ipath);
2252 }
Linux with added FPC-III support