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fanotify: merge duplicate events on parent and child
[linux/fpc-iii.git] / fs / btrfs / backref.c
blobe5d85311d5d5d4eadd857fda99a99bd881074b38
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 separate 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 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, bool lock)
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 if (lock)
741 btrfs_tree_read_lock(eb);
742 if (btrfs_header_level(eb) == 0)
743 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
744 else
745 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
746 if (lock)
747 btrfs_tree_read_unlock(eb);
748 free_extent_buffer(eb);
749 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
750 cond_resched();
751 }
752 return 0;
753 }
754
755 /*
756 * add all currently queued delayed refs from this head whose seq nr is
757 * smaller or equal that seq to the list
758 */
759 static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
760 struct btrfs_delayed_ref_head *head, u64 seq,
761 struct preftrees *preftrees, u64 *total_refs,
762 struct share_check *sc)
763 {
764 struct btrfs_delayed_ref_node *node;
765 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
766 struct btrfs_key key;
767 struct btrfs_key tmp_op_key;
768 struct rb_node *n;
769 int count;
770 int ret = 0;
771
772 if (extent_op && extent_op->update_key)
773 btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
774
775 spin_lock(&head->lock);
776 for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
777 node = rb_entry(n, struct btrfs_delayed_ref_node,
778 ref_node);
779 if (node->seq > seq)
780 continue;
781
782 switch (node->action) {
783 case BTRFS_ADD_DELAYED_EXTENT:
784 case BTRFS_UPDATE_DELAYED_HEAD:
785 WARN_ON(1);
786 continue;
787 case BTRFS_ADD_DELAYED_REF:
788 count = node->ref_mod;
789 break;
790 case BTRFS_DROP_DELAYED_REF:
791 count = node->ref_mod * -1;
792 break;
793 default:
794 BUG();
795 }
796 *total_refs += count;
797 switch (node->type) {
798 case BTRFS_TREE_BLOCK_REF_KEY: {
799 /* NORMAL INDIRECT METADATA backref */
800 struct btrfs_delayed_tree_ref *ref;
801
802 ref = btrfs_delayed_node_to_tree_ref(node);
803 ret = add_indirect_ref(fs_info, preftrees, ref->root,
804 &tmp_op_key, ref->level + 1,
805 node->bytenr, count, sc,
806 GFP_ATOMIC);
807 break;
808 }
809 case BTRFS_SHARED_BLOCK_REF_KEY: {
810 /* SHARED DIRECT METADATA backref */
811 struct btrfs_delayed_tree_ref *ref;
812
813 ref = btrfs_delayed_node_to_tree_ref(node);
814
815 ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
816 ref->parent, node->bytenr, count,
817 sc, GFP_ATOMIC);
818 break;
819 }
820 case BTRFS_EXTENT_DATA_REF_KEY: {
821 /* NORMAL INDIRECT DATA backref */
822 struct btrfs_delayed_data_ref *ref;
823 ref = btrfs_delayed_node_to_data_ref(node);
824
825 key.objectid = ref->objectid;
826 key.type = BTRFS_EXTENT_DATA_KEY;
827 key.offset = ref->offset;
828
829 /*
830 * Found a inum that doesn't match our known inum, we
831 * know it's shared.
832 */
833 if (sc && sc->inum && ref->objectid != sc->inum) {
834 ret = BACKREF_FOUND_SHARED;
835 goto out;
836 }
837
838 ret = add_indirect_ref(fs_info, preftrees, ref->root,
839 &key, 0, node->bytenr, count, sc,
840 GFP_ATOMIC);
841 break;
842 }
843 case BTRFS_SHARED_DATA_REF_KEY: {
844 /* SHARED DIRECT FULL backref */
845 struct btrfs_delayed_data_ref *ref;
846
847 ref = btrfs_delayed_node_to_data_ref(node);
848
849 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
850 node->bytenr, count, sc,
851 GFP_ATOMIC);
852 break;
853 }
854 default:
855 WARN_ON(1);
856 }
857 /*
858 * We must ignore BACKREF_FOUND_SHARED until all delayed
859 * refs have been checked.
860 */
861 if (ret && (ret != BACKREF_FOUND_SHARED))
862 break;
863 }
864 if (!ret)
865 ret = extent_is_shared(sc);
866 out:
867 spin_unlock(&head->lock);
868 return ret;
869 }
870
871 /*
872 * add all inline backrefs for bytenr to the list
873 *
874 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
875 */
876 static int add_inline_refs(const struct btrfs_fs_info *fs_info,
877 struct btrfs_path *path, u64 bytenr,
878 int *info_level, struct preftrees *preftrees,
879 u64 *total_refs, struct share_check *sc)
880 {
881 int ret = 0;
882 int slot;
883 struct extent_buffer *leaf;
884 struct btrfs_key key;
885 struct btrfs_key found_key;
886 unsigned long ptr;
887 unsigned long end;
888 struct btrfs_extent_item *ei;
889 u64 flags;
890 u64 item_size;
891
892 /*
893 * enumerate all inline refs
894 */
895 leaf = path->nodes[0];
896 slot = path->slots[0];
897
898 item_size = btrfs_item_size_nr(leaf, slot);
899 BUG_ON(item_size < sizeof(*ei));
900
901 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
902 flags = btrfs_extent_flags(leaf, ei);
903 *total_refs += btrfs_extent_refs(leaf, ei);
904 btrfs_item_key_to_cpu(leaf, &found_key, slot);
905
906 ptr = (unsigned long)(ei + 1);
907 end = (unsigned long)ei + item_size;
908
909 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
910 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
911 struct btrfs_tree_block_info *info;
912
913 info = (struct btrfs_tree_block_info *)ptr;
914 *info_level = btrfs_tree_block_level(leaf, info);
915 ptr += sizeof(struct btrfs_tree_block_info);
916 BUG_ON(ptr > end);
917 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
918 *info_level = found_key.offset;
919 } else {
920 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
921 }
922
923 while (ptr < end) {
924 struct btrfs_extent_inline_ref *iref;
925 u64 offset;
926 int type;
927
928 iref = (struct btrfs_extent_inline_ref *)ptr;
929 type = btrfs_get_extent_inline_ref_type(leaf, iref,
930 BTRFS_REF_TYPE_ANY);
931 if (type == BTRFS_REF_TYPE_INVALID)
932 return -EUCLEAN;
933
934 offset = btrfs_extent_inline_ref_offset(leaf, iref);
935
936 switch (type) {
937 case BTRFS_SHARED_BLOCK_REF_KEY:
938 ret = add_direct_ref(fs_info, preftrees,
939 *info_level + 1, offset,
940 bytenr, 1, NULL, GFP_NOFS);
941 break;
942 case BTRFS_SHARED_DATA_REF_KEY: {
943 struct btrfs_shared_data_ref *sdref;
944 int count;
945
946 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
947 count = btrfs_shared_data_ref_count(leaf, sdref);
948
949 ret = add_direct_ref(fs_info, preftrees, 0, offset,
950 bytenr, count, sc, GFP_NOFS);
951 break;
952 }
953 case BTRFS_TREE_BLOCK_REF_KEY:
954 ret = add_indirect_ref(fs_info, preftrees, offset,
955 NULL, *info_level + 1,
956 bytenr, 1, NULL, GFP_NOFS);
957 break;
958 case BTRFS_EXTENT_DATA_REF_KEY: {
959 struct btrfs_extent_data_ref *dref;
960 int count;
961 u64 root;
962
963 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
964 count = btrfs_extent_data_ref_count(leaf, dref);
965 key.objectid = btrfs_extent_data_ref_objectid(leaf,
966 dref);
967 key.type = BTRFS_EXTENT_DATA_KEY;
968 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
969
970 if (sc && sc->inum && key.objectid != sc->inum) {
971 ret = BACKREF_FOUND_SHARED;
972 break;
973 }
974
975 root = btrfs_extent_data_ref_root(leaf, dref);
976
977 ret = add_indirect_ref(fs_info, preftrees, root,
978 &key, 0, bytenr, count,
979 sc, GFP_NOFS);
980 break;
981 }
982 default:
983 WARN_ON(1);
984 }
985 if (ret)
986 return ret;
987 ptr += btrfs_extent_inline_ref_size(type);
988 }
989
990 return 0;
991 }
992
993 /*
994 * add all non-inline backrefs for bytenr to the list
995 *
996 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
997 */
998 static int add_keyed_refs(struct btrfs_fs_info *fs_info,
999 struct btrfs_path *path, u64 bytenr,
1000 int info_level, struct preftrees *preftrees,
1001 struct share_check *sc)
1002 {
1003 struct btrfs_root *extent_root = fs_info->extent_root;
1004 int ret;
1005 int slot;
1006 struct extent_buffer *leaf;
1007 struct btrfs_key key;
1008
1009 while (1) {
1010 ret = btrfs_next_item(extent_root, path);
1011 if (ret < 0)
1012 break;
1013 if (ret) {
1014 ret = 0;
1015 break;
1016 }
1017
1018 slot = path->slots[0];
1019 leaf = path->nodes[0];
1020 btrfs_item_key_to_cpu(leaf, &key, slot);
1021
1022 if (key.objectid != bytenr)
1023 break;
1024 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
1025 continue;
1026 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
1027 break;
1028
1029 switch (key.type) {
1030 case BTRFS_SHARED_BLOCK_REF_KEY:
1031 /* SHARED DIRECT METADATA backref */
1032 ret = add_direct_ref(fs_info, preftrees,
1033 info_level + 1, key.offset,
1034 bytenr, 1, NULL, GFP_NOFS);
1035 break;
1036 case BTRFS_SHARED_DATA_REF_KEY: {
1037 /* SHARED DIRECT FULL backref */
1038 struct btrfs_shared_data_ref *sdref;
1039 int count;
1040
1041 sdref = btrfs_item_ptr(leaf, slot,
1042 struct btrfs_shared_data_ref);
1043 count = btrfs_shared_data_ref_count(leaf, sdref);
1044 ret = add_direct_ref(fs_info, preftrees, 0,
1045 key.offset, bytenr, count,
1046 sc, GFP_NOFS);
1047 break;
1048 }
1049 case BTRFS_TREE_BLOCK_REF_KEY:
1050 /* NORMAL INDIRECT METADATA backref */
1051 ret = add_indirect_ref(fs_info, preftrees, key.offset,
1052 NULL, info_level + 1, bytenr,
1053 1, NULL, GFP_NOFS);
1054 break;
1055 case BTRFS_EXTENT_DATA_REF_KEY: {
1056 /* NORMAL INDIRECT DATA backref */
1057 struct btrfs_extent_data_ref *dref;
1058 int count;
1059 u64 root;
1060
1061 dref = btrfs_item_ptr(leaf, slot,
1062 struct btrfs_extent_data_ref);
1063 count = btrfs_extent_data_ref_count(leaf, dref);
1064 key.objectid = btrfs_extent_data_ref_objectid(leaf,
1065 dref);
1066 key.type = BTRFS_EXTENT_DATA_KEY;
1067 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
1068
1069 if (sc && sc->inum && key.objectid != sc->inum) {
1070 ret = BACKREF_FOUND_SHARED;
1071 break;
1072 }
1073
1074 root = btrfs_extent_data_ref_root(leaf, dref);
1075 ret = add_indirect_ref(fs_info, preftrees, root,
1076 &key, 0, bytenr, count,
1077 sc, GFP_NOFS);
1078 break;
1079 }
1080 default:
1081 WARN_ON(1);
1082 }
1083 if (ret)
1084 return ret;
1085
1086 }
1087
1088 return ret;
1089 }
1090
1091 /*
1092 * this adds all existing backrefs (inline backrefs, backrefs and delayed
1093 * refs) for the given bytenr to the refs list, merges duplicates and resolves
1094 * indirect refs to their parent bytenr.
1095 * When roots are found, they're added to the roots list
1096 *
1097 * If time_seq is set to SEQ_LAST, it will not search delayed_refs, and behave
1098 * much like trans == NULL case, the difference only lies in it will not
1099 * commit root.
1100 * The special case is for qgroup to search roots in commit_transaction().
1101 *
1102 * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a
1103 * shared extent is detected.
1104 *
1105 * Otherwise this returns 0 for success and <0 for an error.
1106 *
1107 * If ignore_offset is set to false, only extent refs whose offsets match
1108 * extent_item_pos are returned. If true, every extent ref is returned
1109 * and extent_item_pos is ignored.
1110 *
1111 * FIXME some caching might speed things up
1112 */
1113 static int find_parent_nodes(struct btrfs_trans_handle *trans,
1114 struct btrfs_fs_info *fs_info, u64 bytenr,
1115 u64 time_seq, struct ulist *refs,
1116 struct ulist *roots, const u64 *extent_item_pos,
1117 struct share_check *sc, bool ignore_offset)
1118 {
1119 struct btrfs_key key;
1120 struct btrfs_path *path;
1121 struct btrfs_delayed_ref_root *delayed_refs = NULL;
1122 struct btrfs_delayed_ref_head *head;
1123 int info_level = 0;
1124 int ret;
1125 struct prelim_ref *ref;
1126 struct rb_node *node;
1127 struct extent_inode_elem *eie = NULL;
1128 /* total of both direct AND indirect refs! */
1129 u64 total_refs = 0;
1130 struct preftrees preftrees = {
1131 .direct = PREFTREE_INIT,
1132 .indirect = PREFTREE_INIT,
1133 .indirect_missing_keys = PREFTREE_INIT
1134 };
1135
1136 key.objectid = bytenr;
1137 key.offset = (u64)-1;
1138 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1139 key.type = BTRFS_METADATA_ITEM_KEY;
1140 else
1141 key.type = BTRFS_EXTENT_ITEM_KEY;
1142
1143 path = btrfs_alloc_path();
1144 if (!path)
1145 return -ENOMEM;
1146 if (!trans) {
1147 path->search_commit_root = 1;
1148 path->skip_locking = 1;
1149 }
1150
1151 if (time_seq == SEQ_LAST)
1152 path->skip_locking = 1;
1153
1154 /*
1155 * grab both a lock on the path and a lock on the delayed ref head.
1156 * We need both to get a consistent picture of how the refs look
1157 * at a specified point in time
1158 */
1159 again:
1160 head = NULL;
1161
1162 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
1163 if (ret < 0)
1164 goto out;
1165 BUG_ON(ret == 0);
1166
1167 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1168 if (trans && likely(trans->type != __TRANS_DUMMY) &&
1169 time_seq != SEQ_LAST) {
1170 #else
1171 if (trans && time_seq != SEQ_LAST) {
1172 #endif
1173 /*
1174 * look if there are updates for this ref queued and lock the
1175 * head
1176 */
1177 delayed_refs = &trans->transaction->delayed_refs;
1178 spin_lock(&delayed_refs->lock);
1179 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
1180 if (head) {
1181 if (!mutex_trylock(&head->mutex)) {
1182 refcount_inc(&head->refs);
1183 spin_unlock(&delayed_refs->lock);
1184
1185 btrfs_release_path(path);
1186
1187 /*
1188 * Mutex was contended, block until it's
1189 * released and try again
1190 */
1191 mutex_lock(&head->mutex);
1192 mutex_unlock(&head->mutex);
1193 btrfs_put_delayed_ref_head(head);
1194 goto again;
1195 }
1196 spin_unlock(&delayed_refs->lock);
1197 ret = add_delayed_refs(fs_info, head, time_seq,
1198 &preftrees, &total_refs, sc);
1199 mutex_unlock(&head->mutex);
1200 if (ret)
1201 goto out;
1202 } else {
1203 spin_unlock(&delayed_refs->lock);
1204 }
1205 }
1206
1207 if (path->slots[0]) {
1208 struct extent_buffer *leaf;
1209 int slot;
1210
1211 path->slots[0]--;
1212 leaf = path->nodes[0];
1213 slot = path->slots[0];
1214 btrfs_item_key_to_cpu(leaf, &key, slot);
1215 if (key.objectid == bytenr &&
1216 (key.type == BTRFS_EXTENT_ITEM_KEY ||
1217 key.type == BTRFS_METADATA_ITEM_KEY)) {
1218 ret = add_inline_refs(fs_info, path, bytenr,
1219 &info_level, &preftrees,
1220 &total_refs, sc);
1221 if (ret)
1222 goto out;
1223 ret = add_keyed_refs(fs_info, path, bytenr, info_level,
1224 &preftrees, sc);
1225 if (ret)
1226 goto out;
1227 }
1228 }
1229
1230 btrfs_release_path(path);
1231
1232 ret = add_missing_keys(fs_info, &preftrees, path->skip_locking == 0);
1233 if (ret)
1234 goto out;
1235
1236 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root));
1237
1238 ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees,
1239 extent_item_pos, total_refs, sc, ignore_offset);
1240 if (ret)
1241 goto out;
1242
1243 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root));
1244
1245 /*
1246 * This walks the tree of merged and resolved refs. Tree blocks are
1247 * read in as needed. Unique entries are added to the ulist, and
1248 * the list of found roots is updated.
1249 *
1250 * We release the entire tree in one go before returning.
1251 */
1252 node = rb_first_cached(&preftrees.direct.root);
1253 while (node) {
1254 ref = rb_entry(node, struct prelim_ref, rbnode);
1255 node = rb_next(&ref->rbnode);
1256 /*
1257 * ref->count < 0 can happen here if there are delayed
1258 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
1259 * prelim_ref_insert() relies on this when merging
1260 * identical refs to keep the overall count correct.
1261 * prelim_ref_insert() will merge only those refs
1262 * which compare identically. Any refs having
1263 * e.g. different offsets would not be merged,
1264 * and would retain their original ref->count < 0.
1265 */
1266 if (roots && ref->count && ref->root_id && ref->parent == 0) {
1267 if (sc && sc->root_objectid &&
1268 ref->root_id != sc->root_objectid) {
1269 ret = BACKREF_FOUND_SHARED;
1270 goto out;
1271 }
1272
1273 /* no parent == root of tree */
1274 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
1275 if (ret < 0)
1276 goto out;
1277 }
1278 if (ref->count && ref->parent) {
1279 if (extent_item_pos && !ref->inode_list &&
1280 ref->level == 0) {
1281 struct extent_buffer *eb;
1282
1283 eb = read_tree_block(fs_info, ref->parent, 0,
1284 ref->level, NULL);
1285 if (IS_ERR(eb)) {
1286 ret = PTR_ERR(eb);
1287 goto out;
1288 } else if (!extent_buffer_uptodate(eb)) {
1289 free_extent_buffer(eb);
1290 ret = -EIO;
1291 goto out;
1292 }
1293
1294 if (!path->skip_locking) {
1295 btrfs_tree_read_lock(eb);
1296 btrfs_set_lock_blocking_read(eb);
1297 }
1298 ret = find_extent_in_eb(eb, bytenr,
1299 *extent_item_pos, &eie, ignore_offset);
1300 if (!path->skip_locking)
1301 btrfs_tree_read_unlock_blocking(eb);
1302 free_extent_buffer(eb);
1303 if (ret < 0)
1304 goto out;
1305 ref->inode_list = eie;
1306 }
1307 ret = ulist_add_merge_ptr(refs, ref->parent,
1308 ref->inode_list,
1309 (void **)&eie, GFP_NOFS);
1310 if (ret < 0)
1311 goto out;
1312 if (!ret && extent_item_pos) {
1313 /*
1314 * we've recorded that parent, so we must extend
1315 * its inode list here
1316 */
1317 BUG_ON(!eie);
1318 while (eie->next)
1319 eie = eie->next;
1320 eie->next = ref->inode_list;
1321 }
1322 eie = NULL;
1323 }
1324 cond_resched();
1325 }
1326
1327 out:
1328 btrfs_free_path(path);
1329
1330 prelim_release(&preftrees.direct);
1331 prelim_release(&preftrees.indirect);
1332 prelim_release(&preftrees.indirect_missing_keys);
1333
1334 if (ret < 0)
1335 free_inode_elem_list(eie);
1336 return ret;
1337 }
1338
1339 static void free_leaf_list(struct ulist *blocks)
1340 {
1341 struct ulist_node *node = NULL;
1342 struct extent_inode_elem *eie;
1343 struct ulist_iterator uiter;
1344
1345 ULIST_ITER_INIT(&uiter);
1346 while ((node = ulist_next(blocks, &uiter))) {
1347 if (!node->aux)
1348 continue;
1349 eie = unode_aux_to_inode_list(node);
1350 free_inode_elem_list(eie);
1351 node->aux = 0;
1352 }
1353
1354 ulist_free(blocks);
1355 }
1356
1357 /*
1358 * Finds all leafs with a reference to the specified combination of bytenr and
1359 * offset. key_list_head will point to a list of corresponding keys (caller must
1360 * free each list element). The leafs will be stored in the leafs ulist, which
1361 * must be freed with ulist_free.
1362 *
1363 * returns 0 on success, <0 on error
1364 */
1365 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1366 struct btrfs_fs_info *fs_info, u64 bytenr,
1367 u64 time_seq, struct ulist **leafs,
1368 const u64 *extent_item_pos, bool ignore_offset)
1369 {
1370 int ret;
1371
1372 *leafs = ulist_alloc(GFP_NOFS);
1373 if (!*leafs)
1374 return -ENOMEM;
1375
1376 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1377 *leafs, NULL, extent_item_pos, NULL, ignore_offset);
1378 if (ret < 0 && ret != -ENOENT) {
1379 free_leaf_list(*leafs);
1380 return ret;
1381 }
1382
1383 return 0;
1384 }
1385
1386 /*
1387 * walk all backrefs for a given extent to find all roots that reference this
1388 * extent. Walking a backref means finding all extents that reference this
1389 * extent and in turn walk the backrefs of those, too. Naturally this is a
1390 * recursive process, but here it is implemented in an iterative fashion: We
1391 * find all referencing extents for the extent in question and put them on a
1392 * list. In turn, we find all referencing extents for those, further appending
1393 * to the list. The way we iterate the list allows adding more elements after
1394 * the current while iterating. The process stops when we reach the end of the
1395 * list. Found roots are added to the roots list.
1396 *
1397 * returns 0 on success, < 0 on error.
1398 */
1399 static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
1400 struct btrfs_fs_info *fs_info, u64 bytenr,
1401 u64 time_seq, struct ulist **roots,
1402 bool ignore_offset)
1403 {
1404 struct ulist *tmp;
1405 struct ulist_node *node = NULL;
1406 struct ulist_iterator uiter;
1407 int ret;
1408
1409 tmp = ulist_alloc(GFP_NOFS);
1410 if (!tmp)
1411 return -ENOMEM;
1412 *roots = ulist_alloc(GFP_NOFS);
1413 if (!*roots) {
1414 ulist_free(tmp);
1415 return -ENOMEM;
1416 }
1417
1418 ULIST_ITER_INIT(&uiter);
1419 while (1) {
1420 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1421 tmp, *roots, NULL, NULL, ignore_offset);
1422 if (ret < 0 && ret != -ENOENT) {
1423 ulist_free(tmp);
1424 ulist_free(*roots);
1425 return ret;
1426 }
1427 node = ulist_next(tmp, &uiter);
1428 if (!node)
1429 break;
1430 bytenr = node->val;
1431 cond_resched();
1432 }
1433
1434 ulist_free(tmp);
1435 return 0;
1436 }
1437
1438 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1439 struct btrfs_fs_info *fs_info, u64 bytenr,
1440 u64 time_seq, struct ulist **roots,
1441 bool ignore_offset)
1442 {
1443 int ret;
1444
1445 if (!trans)
1446 down_read(&fs_info->commit_root_sem);
1447 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr,
1448 time_seq, roots, ignore_offset);
1449 if (!trans)
1450 up_read(&fs_info->commit_root_sem);
1451 return ret;
1452 }
1453
1454 /**
1455 * btrfs_check_shared - tell us whether an extent is shared
1456 *
1457 * btrfs_check_shared uses the backref walking code but will short
1458 * circuit as soon as it finds a root or inode that doesn't match the
1459 * one passed in. This provides a significant performance benefit for
1460 * callers (such as fiemap) which want to know whether the extent is
1461 * shared but do not need a ref count.
1462 *
1463 * This attempts to attach to the running transaction in order to account for
1464 * delayed refs, but continues on even when no running transaction exists.
1465 *
1466 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1467 */
1468 int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr,
1469 struct ulist *roots, struct ulist *tmp)
1470 {
1471 struct btrfs_fs_info *fs_info = root->fs_info;
1472 struct btrfs_trans_handle *trans;
1473 struct ulist_iterator uiter;
1474 struct ulist_node *node;
1475 struct seq_list elem = SEQ_LIST_INIT(elem);
1476 int ret = 0;
1477 struct share_check shared = {
1478 .root_objectid = root->root_key.objectid,
1479 .inum = inum,
1480 .share_count = 0,
1481 };
1482
1483 ulist_init(roots);
1484 ulist_init(tmp);
1485
1486 trans = btrfs_join_transaction_nostart(root);
1487 if (IS_ERR(trans)) {
1488 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
1489 ret = PTR_ERR(trans);
1490 goto out;
1491 }
1492 trans = NULL;
1493 down_read(&fs_info->commit_root_sem);
1494 } else {
1495 btrfs_get_tree_mod_seq(fs_info, &elem);
1496 }
1497
1498 ULIST_ITER_INIT(&uiter);
1499 while (1) {
1500 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1501 roots, NULL, &shared, false);
1502 if (ret == BACKREF_FOUND_SHARED) {
1503 /* this is the only condition under which we return 1 */
1504 ret = 1;
1505 break;
1506 }
1507 if (ret < 0 && ret != -ENOENT)
1508 break;
1509 ret = 0;
1510 node = ulist_next(tmp, &uiter);
1511 if (!node)
1512 break;
1513 bytenr = node->val;
1514 shared.share_count = 0;
1515 cond_resched();
1516 }
1517
1518 if (trans) {
1519 btrfs_put_tree_mod_seq(fs_info, &elem);
1520 btrfs_end_transaction(trans);
1521 } else {
1522 up_read(&fs_info->commit_root_sem);
1523 }
1524 out:
1525 ulist_release(roots);
1526 ulist_release(tmp);
1527 return ret;
1528 }
1529
1530 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1531 u64 start_off, struct btrfs_path *path,
1532 struct btrfs_inode_extref **ret_extref,
1533 u64 *found_off)
1534 {
1535 int ret, slot;
1536 struct btrfs_key key;
1537 struct btrfs_key found_key;
1538 struct btrfs_inode_extref *extref;
1539 const struct extent_buffer *leaf;
1540 unsigned long ptr;
1541
1542 key.objectid = inode_objectid;
1543 key.type = BTRFS_INODE_EXTREF_KEY;
1544 key.offset = start_off;
1545
1546 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1547 if (ret < 0)
1548 return ret;
1549
1550 while (1) {
1551 leaf = path->nodes[0];
1552 slot = path->slots[0];
1553 if (slot >= btrfs_header_nritems(leaf)) {
1554 /*
1555 * If the item at offset is not found,
1556 * btrfs_search_slot will point us to the slot
1557 * where it should be inserted. In our case
1558 * that will be the slot directly before the
1559 * next INODE_REF_KEY_V2 item. In the case
1560 * that we're pointing to the last slot in a
1561 * leaf, we must move one leaf over.
1562 */
1563 ret = btrfs_next_leaf(root, path);
1564 if (ret) {
1565 if (ret >= 1)
1566 ret = -ENOENT;
1567 break;
1568 }
1569 continue;
1570 }
1571
1572 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1573
1574 /*
1575 * Check that we're still looking at an extended ref key for
1576 * this particular objectid. If we have different
1577 * objectid or type then there are no more to be found
1578 * in the tree and we can exit.
1579 */
1580 ret = -ENOENT;
1581 if (found_key.objectid != inode_objectid)
1582 break;
1583 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1584 break;
1585
1586 ret = 0;
1587 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1588 extref = (struct btrfs_inode_extref *)ptr;
1589 *ret_extref = extref;
1590 if (found_off)
1591 *found_off = found_key.offset;
1592 break;
1593 }
1594
1595 return ret;
1596 }
1597
1598 /*
1599 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1600 * Elements of the path are separated by '/' and the path is guaranteed to be
1601 * 0-terminated. the path is only given within the current file system.
1602 * Therefore, it never starts with a '/'. the caller is responsible to provide
1603 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1604 * the start point of the resulting string is returned. this pointer is within
1605 * dest, normally.
1606 * in case the path buffer would overflow, the pointer is decremented further
1607 * as if output was written to the buffer, though no more output is actually
1608 * generated. that way, the caller can determine how much space would be
1609 * required for the path to fit into the buffer. in that case, the returned
1610 * value will be smaller than dest. callers must check this!
1611 */
1612 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1613 u32 name_len, unsigned long name_off,
1614 struct extent_buffer *eb_in, u64 parent,
1615 char *dest, u32 size)
1616 {
1617 int slot;
1618 u64 next_inum;
1619 int ret;
1620 s64 bytes_left = ((s64)size) - 1;
1621 struct extent_buffer *eb = eb_in;
1622 struct btrfs_key found_key;
1623 int leave_spinning = path->leave_spinning;
1624 struct btrfs_inode_ref *iref;
1625
1626 if (bytes_left >= 0)
1627 dest[bytes_left] = '\0';
1628
1629 path->leave_spinning = 1;
1630 while (1) {
1631 bytes_left -= name_len;
1632 if (bytes_left >= 0)
1633 read_extent_buffer(eb, dest + bytes_left,
1634 name_off, name_len);
1635 if (eb != eb_in) {
1636 if (!path->skip_locking)
1637 btrfs_tree_read_unlock_blocking(eb);
1638 free_extent_buffer(eb);
1639 }
1640 ret = btrfs_find_item(fs_root, path, parent, 0,
1641 BTRFS_INODE_REF_KEY, &found_key);
1642 if (ret > 0)
1643 ret = -ENOENT;
1644 if (ret)
1645 break;
1646
1647 next_inum = found_key.offset;
1648
1649 /* regular exit ahead */
1650 if (parent == next_inum)
1651 break;
1652
1653 slot = path->slots[0];
1654 eb = path->nodes[0];
1655 /* make sure we can use eb after releasing the path */
1656 if (eb != eb_in) {
1657 if (!path->skip_locking)
1658 btrfs_set_lock_blocking_read(eb);
1659 path->nodes[0] = NULL;
1660 path->locks[0] = 0;
1661 }
1662 btrfs_release_path(path);
1663 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1664
1665 name_len = btrfs_inode_ref_name_len(eb, iref);
1666 name_off = (unsigned long)(iref + 1);
1667
1668 parent = next_inum;
1669 --bytes_left;
1670 if (bytes_left >= 0)
1671 dest[bytes_left] = '/';
1672 }
1673
1674 btrfs_release_path(path);
1675 path->leave_spinning = leave_spinning;
1676
1677 if (ret)
1678 return ERR_PTR(ret);
1679
1680 return dest + bytes_left;
1681 }
1682
1683 /*
1684 * this makes the path point to (logical EXTENT_ITEM *)
1685 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1686 * tree blocks and <0 on error.
1687 */
1688 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1689 struct btrfs_path *path, struct btrfs_key *found_key,
1690 u64 *flags_ret)
1691 {
1692 int ret;
1693 u64 flags;
1694 u64 size = 0;
1695 u32 item_size;
1696 const struct extent_buffer *eb;
1697 struct btrfs_extent_item *ei;
1698 struct btrfs_key key;
1699
1700 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1701 key.type = BTRFS_METADATA_ITEM_KEY;
1702 else
1703 key.type = BTRFS_EXTENT_ITEM_KEY;
1704 key.objectid = logical;
1705 key.offset = (u64)-1;
1706
1707 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1708 if (ret < 0)
1709 return ret;
1710
1711 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1712 if (ret) {
1713 if (ret > 0)
1714 ret = -ENOENT;
1715 return ret;
1716 }
1717 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1718 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1719 size = fs_info->nodesize;
1720 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1721 size = found_key->offset;
1722
1723 if (found_key->objectid > logical ||
1724 found_key->objectid + size <= logical) {
1725 btrfs_debug(fs_info,
1726 "logical %llu is not within any extent", logical);
1727 return -ENOENT;
1728 }
1729
1730 eb = path->nodes[0];
1731 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1732 BUG_ON(item_size < sizeof(*ei));
1733
1734 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1735 flags = btrfs_extent_flags(eb, ei);
1736
1737 btrfs_debug(fs_info,
1738 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1739 logical, logical - found_key->objectid, found_key->objectid,
1740 found_key->offset, flags, item_size);
1741
1742 WARN_ON(!flags_ret);
1743 if (flags_ret) {
1744 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1745 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1746 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1747 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1748 else
1749 BUG();
1750 return 0;
1751 }
1752
1753 return -EIO;
1754 }
1755
1756 /*
1757 * helper function to iterate extent inline refs. ptr must point to a 0 value
1758 * for the first call and may be modified. it is used to track state.
1759 * if more refs exist, 0 is returned and the next call to
1760 * get_extent_inline_ref must pass the modified ptr parameter to get the
1761 * next ref. after the last ref was processed, 1 is returned.
1762 * returns <0 on error
1763 */
1764 static int get_extent_inline_ref(unsigned long *ptr,
1765 const struct extent_buffer *eb,
1766 const struct btrfs_key *key,
1767 const struct btrfs_extent_item *ei,
1768 u32 item_size,
1769 struct btrfs_extent_inline_ref **out_eiref,
1770 int *out_type)
1771 {
1772 unsigned long end;
1773 u64 flags;
1774 struct btrfs_tree_block_info *info;
1775
1776 if (!*ptr) {
1777 /* first call */
1778 flags = btrfs_extent_flags(eb, ei);
1779 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1780 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1781 /* a skinny metadata extent */
1782 *out_eiref =
1783 (struct btrfs_extent_inline_ref *)(ei + 1);
1784 } else {
1785 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1786 info = (struct btrfs_tree_block_info *)(ei + 1);
1787 *out_eiref =
1788 (struct btrfs_extent_inline_ref *)(info + 1);
1789 }
1790 } else {
1791 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1792 }
1793 *ptr = (unsigned long)*out_eiref;
1794 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1795 return -ENOENT;
1796 }
1797
1798 end = (unsigned long)ei + item_size;
1799 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1800 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
1801 BTRFS_REF_TYPE_ANY);
1802 if (*out_type == BTRFS_REF_TYPE_INVALID)
1803 return -EUCLEAN;
1804
1805 *ptr += btrfs_extent_inline_ref_size(*out_type);
1806 WARN_ON(*ptr > end);
1807 if (*ptr == end)
1808 return 1; /* last */
1809
1810 return 0;
1811 }
1812
1813 /*
1814 * reads the tree block backref for an extent. tree level and root are returned
1815 * through out_level and out_root. ptr must point to a 0 value for the first
1816 * call and may be modified (see get_extent_inline_ref comment).
1817 * returns 0 if data was provided, 1 if there was no more data to provide or
1818 * <0 on error.
1819 */
1820 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1821 struct btrfs_key *key, struct btrfs_extent_item *ei,
1822 u32 item_size, u64 *out_root, u8 *out_level)
1823 {
1824 int ret;
1825 int type;
1826 struct btrfs_extent_inline_ref *eiref;
1827
1828 if (*ptr == (unsigned long)-1)
1829 return 1;
1830
1831 while (1) {
1832 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
1833 &eiref, &type);
1834 if (ret < 0)
1835 return ret;
1836
1837 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1838 type == BTRFS_SHARED_BLOCK_REF_KEY)
1839 break;
1840
1841 if (ret == 1)
1842 return 1;
1843 }
1844
1845 /* we can treat both ref types equally here */
1846 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1847
1848 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1849 struct btrfs_tree_block_info *info;
1850
1851 info = (struct btrfs_tree_block_info *)(ei + 1);
1852 *out_level = btrfs_tree_block_level(eb, info);
1853 } else {
1854 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1855 *out_level = (u8)key->offset;
1856 }
1857
1858 if (ret == 1)
1859 *ptr = (unsigned long)-1;
1860
1861 return 0;
1862 }
1863
1864 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1865 struct extent_inode_elem *inode_list,
1866 u64 root, u64 extent_item_objectid,
1867 iterate_extent_inodes_t *iterate, void *ctx)
1868 {
1869 struct extent_inode_elem *eie;
1870 int ret = 0;
1871
1872 for (eie = inode_list; eie; eie = eie->next) {
1873 btrfs_debug(fs_info,
1874 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1875 extent_item_objectid, eie->inum,
1876 eie->offset, root);
1877 ret = iterate(eie->inum, eie->offset, root, ctx);
1878 if (ret) {
1879 btrfs_debug(fs_info,
1880 "stopping iteration for %llu due to ret=%d",
1881 extent_item_objectid, ret);
1882 break;
1883 }
1884 }
1885
1886 return ret;
1887 }
1888
1889 /*
1890 * calls iterate() for every inode that references the extent identified by
1891 * the given parameters.
1892 * when the iterator function returns a non-zero value, iteration stops.
1893 */
1894 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1895 u64 extent_item_objectid, u64 extent_item_pos,
1896 int search_commit_root,
1897 iterate_extent_inodes_t *iterate, void *ctx,
1898 bool ignore_offset)
1899 {
1900 int ret;
1901 struct btrfs_trans_handle *trans = NULL;
1902 struct ulist *refs = NULL;
1903 struct ulist *roots = NULL;
1904 struct ulist_node *ref_node = NULL;
1905 struct ulist_node *root_node = NULL;
1906 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
1907 struct ulist_iterator ref_uiter;
1908 struct ulist_iterator root_uiter;
1909
1910 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
1911 extent_item_objectid);
1912
1913 if (!search_commit_root) {
1914 trans = btrfs_attach_transaction(fs_info->extent_root);
1915 if (IS_ERR(trans)) {
1916 if (PTR_ERR(trans) != -ENOENT &&
1917 PTR_ERR(trans) != -EROFS)
1918 return PTR_ERR(trans);
1919 trans = NULL;
1920 }
1921 }
1922
1923 if (trans)
1924 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1925 else
1926 down_read(&fs_info->commit_root_sem);
1927
1928 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1929 tree_mod_seq_elem.seq, &refs,
1930 &extent_item_pos, ignore_offset);
1931 if (ret)
1932 goto out;
1933
1934 ULIST_ITER_INIT(&ref_uiter);
1935 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1936 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val,
1937 tree_mod_seq_elem.seq, &roots,
1938 ignore_offset);
1939 if (ret)
1940 break;
1941 ULIST_ITER_INIT(&root_uiter);
1942 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1943 btrfs_debug(fs_info,
1944 "root %llu references leaf %llu, data list %#llx",
1945 root_node->val, ref_node->val,
1946 ref_node->aux);
1947 ret = iterate_leaf_refs(fs_info,
1948 (struct extent_inode_elem *)
1949 (uintptr_t)ref_node->aux,
1950 root_node->val,
1951 extent_item_objectid,
1952 iterate, ctx);
1953 }
1954 ulist_free(roots);
1955 }
1956
1957 free_leaf_list(refs);
1958 out:
1959 if (trans) {
1960 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1961 btrfs_end_transaction(trans);
1962 } else {
1963 up_read(&fs_info->commit_root_sem);
1964 }
1965
1966 return ret;
1967 }
1968
1969 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1970 struct btrfs_path *path,
1971 iterate_extent_inodes_t *iterate, void *ctx,
1972 bool ignore_offset)
1973 {
1974 int ret;
1975 u64 extent_item_pos;
1976 u64 flags = 0;
1977 struct btrfs_key found_key;
1978 int search_commit_root = path->search_commit_root;
1979
1980 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1981 btrfs_release_path(path);
1982 if (ret < 0)
1983 return ret;
1984 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1985 return -EINVAL;
1986
1987 extent_item_pos = logical - found_key.objectid;
1988 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1989 extent_item_pos, search_commit_root,
1990 iterate, ctx, ignore_offset);
1991
1992 return ret;
1993 }
1994
1995 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1996 struct extent_buffer *eb, void *ctx);
1997
1998 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1999 struct btrfs_path *path,
2000 iterate_irefs_t *iterate, void *ctx)
2001 {
2002 int ret = 0;
2003 int slot;
2004 u32 cur;
2005 u32 len;
2006 u32 name_len;
2007 u64 parent = 0;
2008 int found = 0;
2009 struct extent_buffer *eb;
2010 struct btrfs_item *item;
2011 struct btrfs_inode_ref *iref;
2012 struct btrfs_key found_key;
2013
2014 while (!ret) {
2015 ret = btrfs_find_item(fs_root, path, inum,
2016 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2017 &found_key);
2018
2019 if (ret < 0)
2020 break;
2021 if (ret) {
2022 ret = found ? 0 : -ENOENT;
2023 break;
2024 }
2025 ++found;
2026
2027 parent = found_key.offset;
2028 slot = path->slots[0];
2029 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2030 if (!eb) {
2031 ret = -ENOMEM;
2032 break;
2033 }
2034 btrfs_release_path(path);
2035
2036 item = btrfs_item_nr(slot);
2037 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2038
2039 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
2040 name_len = btrfs_inode_ref_name_len(eb, iref);
2041 /* path must be released before calling iterate()! */
2042 btrfs_debug(fs_root->fs_info,
2043 "following ref at offset %u for inode %llu in tree %llu",
2044 cur, found_key.objectid,
2045 fs_root->root_key.objectid);
2046 ret = iterate(parent, name_len,
2047 (unsigned long)(iref + 1), eb, ctx);
2048 if (ret)
2049 break;
2050 len = sizeof(*iref) + name_len;
2051 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2052 }
2053 free_extent_buffer(eb);
2054 }
2055
2056 btrfs_release_path(path);
2057
2058 return ret;
2059 }
2060
2061 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
2062 struct btrfs_path *path,
2063 iterate_irefs_t *iterate, void *ctx)
2064 {
2065 int ret;
2066 int slot;
2067 u64 offset = 0;
2068 u64 parent;
2069 int found = 0;
2070 struct extent_buffer *eb;
2071 struct btrfs_inode_extref *extref;
2072 u32 item_size;
2073 u32 cur_offset;
2074 unsigned long ptr;
2075
2076 while (1) {
2077 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2078 &offset);
2079 if (ret < 0)
2080 break;
2081 if (ret) {
2082 ret = found ? 0 : -ENOENT;
2083 break;
2084 }
2085 ++found;
2086
2087 slot = path->slots[0];
2088 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2089 if (!eb) {
2090 ret = -ENOMEM;
2091 break;
2092 }
2093 btrfs_release_path(path);
2094
2095 item_size = btrfs_item_size_nr(eb, slot);
2096 ptr = btrfs_item_ptr_offset(eb, slot);
2097 cur_offset = 0;
2098
2099 while (cur_offset < item_size) {
2100 u32 name_len;
2101
2102 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2103 parent = btrfs_inode_extref_parent(eb, extref);
2104 name_len = btrfs_inode_extref_name_len(eb, extref);
2105 ret = iterate(parent, name_len,
2106 (unsigned long)&extref->name, eb, ctx);
2107 if (ret)
2108 break;
2109
2110 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2111 cur_offset += sizeof(*extref);
2112 }
2113 free_extent_buffer(eb);
2114
2115 offset++;
2116 }
2117
2118 btrfs_release_path(path);
2119
2120 return ret;
2121 }
2122
2123 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
2124 struct btrfs_path *path, iterate_irefs_t *iterate,
2125 void *ctx)
2126 {
2127 int ret;
2128 int found_refs = 0;
2129
2130 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
2131 if (!ret)
2132 ++found_refs;
2133 else if (ret != -ENOENT)
2134 return ret;
2135
2136 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
2137 if (ret == -ENOENT && found_refs)
2138 return 0;
2139
2140 return ret;
2141 }
2142
2143 /*
2144 * returns 0 if the path could be dumped (probably truncated)
2145 * returns <0 in case of an error
2146 */
2147 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2148 struct extent_buffer *eb, void *ctx)
2149 {
2150 struct inode_fs_paths *ipath = ctx;
2151 char *fspath;
2152 char *fspath_min;
2153 int i = ipath->fspath->elem_cnt;
2154 const int s_ptr = sizeof(char *);
2155 u32 bytes_left;
2156
2157 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2158 ipath->fspath->bytes_left - s_ptr : 0;
2159
2160 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2161 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2162 name_off, eb, inum, fspath_min, bytes_left);
2163 if (IS_ERR(fspath))
2164 return PTR_ERR(fspath);
2165
2166 if (fspath > fspath_min) {
2167 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2168 ++ipath->fspath->elem_cnt;
2169 ipath->fspath->bytes_left = fspath - fspath_min;
2170 } else {
2171 ++ipath->fspath->elem_missed;
2172 ipath->fspath->bytes_missing += fspath_min - fspath;
2173 ipath->fspath->bytes_left = 0;
2174 }
2175
2176 return 0;
2177 }
2178
2179 /*
2180 * this dumps all file system paths to the inode into the ipath struct, provided
2181 * is has been created large enough. each path is zero-terminated and accessed
2182 * from ipath->fspath->val[i].
2183 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2184 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2185 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2186 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2187 * have been needed to return all paths.
2188 */
2189 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2190 {
2191 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
2192 inode_to_path, ipath);
2193 }
2194
2195 struct btrfs_data_container *init_data_container(u32 total_bytes)
2196 {
2197 struct btrfs_data_container *data;
2198 size_t alloc_bytes;
2199
2200 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2201 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2202 if (!data)
2203 return ERR_PTR(-ENOMEM);
2204
2205 if (total_bytes >= sizeof(*data)) {
2206 data->bytes_left = total_bytes - sizeof(*data);
2207 data->bytes_missing = 0;
2208 } else {
2209 data->bytes_missing = sizeof(*data) - total_bytes;
2210 data->bytes_left = 0;
2211 }
2212
2213 data->elem_cnt = 0;
2214 data->elem_missed = 0;
2215
2216 return data;
2217 }
2218
2219 /*
2220 * allocates space to return multiple file system paths for an inode.
2221 * total_bytes to allocate are passed, note that space usable for actual path
2222 * information will be total_bytes - sizeof(struct inode_fs_paths).
2223 * the returned pointer must be freed with free_ipath() in the end.
2224 */
2225 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2226 struct btrfs_path *path)
2227 {
2228 struct inode_fs_paths *ifp;
2229 struct btrfs_data_container *fspath;
2230
2231 fspath = init_data_container(total_bytes);
2232 if (IS_ERR(fspath))
2233 return ERR_CAST(fspath);
2234
2235 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2236 if (!ifp) {
2237 kvfree(fspath);
2238 return ERR_PTR(-ENOMEM);
2239 }
2240
2241 ifp->btrfs_path = path;
2242 ifp->fspath = fspath;
2243 ifp->fs_root = fs_root;
2244
2245 return ifp;
2246 }
2247
2248 void free_ipath(struct inode_fs_paths *ipath)
2249 {
2250 if (!ipath)
2251 return;
2252 kvfree(ipath->fspath);
2253 kfree(ipath);
2254 }
Linux with added FPC-III support