?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Linux 4.19.133
[linux/fpc-iii.git] / fs / btrfs / backref.c
blob19855659f65030d57d1e56fb5f93341ab4efe477
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 root;
116 unsigned int count;
117 };
118
119 #define PREFTREE_INIT { .root = RB_ROOT, .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 *root;
229 struct rb_node **p;
230 struct rb_node *parent = NULL;
231 struct prelim_ref *ref;
232 int result;
233
234 root = &preftree->root;
235 p = &root->rb_node;
236
237 while (*p) {
238 parent = *p;
239 ref = rb_entry(parent, struct prelim_ref, rbnode);
240 result = prelim_ref_compare(ref, newref);
241 if (result < 0) {
242 p = &(*p)->rb_left;
243 } else if (result > 0) {
244 p = &(*p)->rb_right;
245 } else {
246 /* Identical refs, merge them and free @newref */
247 struct extent_inode_elem *eie = ref->inode_list;
248
249 while (eie && eie->next)
250 eie = eie->next;
251
252 if (!eie)
253 ref->inode_list = newref->inode_list;
254 else
255 eie->next = newref->inode_list;
256 trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
257 preftree->count);
258 /*
259 * A delayed ref can have newref->count < 0.
260 * The ref->count is updated to follow any
261 * BTRFS_[ADD|DROP]_DELAYED_REF actions.
262 */
263 update_share_count(sc, ref->count,
264 ref->count + newref->count);
265 ref->count += newref->count;
266 free_pref(newref);
267 return;
268 }
269 }
270
271 update_share_count(sc, 0, newref->count);
272 preftree->count++;
273 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
274 rb_link_node(&newref->rbnode, parent, p);
275 rb_insert_color(&newref->rbnode, root);
276 }
277
278 /*
279 * Release the entire tree. We don't care about internal consistency so
280 * just free everything and then reset the tree root.
281 */
282 static void prelim_release(struct preftree *preftree)
283 {
284 struct prelim_ref *ref, *next_ref;
285
286 rbtree_postorder_for_each_entry_safe(ref, next_ref, &preftree->root,
287 rbnode)
288 free_pref(ref);
289
290 preftree->root = RB_ROOT;
291 preftree->count = 0;
292 }
293
294 /*
295 * the rules for all callers of this function are:
296 * - obtaining the parent is the goal
297 * - if you add a key, you must know that it is a correct key
298 * - if you cannot add the parent or a correct key, then we will look into the
299 * block later to set a correct key
300 *
301 * delayed refs
302 * ============
303 * backref type | shared | indirect | shared | indirect
304 * information | tree | tree | data | data
305 * --------------------+--------+----------+--------+----------
306 * parent logical | y | - | - | -
307 * key to resolve | - | y | y | y
308 * tree block logical | - | - | - | -
309 * root for resolving | y | y | y | y
310 *
311 * - column 1: we've the parent -> done
312 * - column 2, 3, 4: we use the key to find the parent
313 *
314 * on disk refs (inline or keyed)
315 * ==============================
316 * backref type | shared | indirect | shared | indirect
317 * information | tree | tree | data | data
318 * --------------------+--------+----------+--------+----------
319 * parent logical | y | - | y | -
320 * key to resolve | - | - | - | y
321 * tree block logical | y | y | y | y
322 * root for resolving | - | y | y | y
323 *
324 * - column 1, 3: we've the parent -> done
325 * - column 2: we take the first key from the block to find the parent
326 * (see add_missing_keys)
327 * - column 4: we use the key to find the parent
328 *
329 * additional information that's available but not required to find the parent
330 * block might help in merging entries to gain some speed.
331 */
332 static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
333 struct preftree *preftree, u64 root_id,
334 const struct btrfs_key *key, int level, u64 parent,
335 u64 wanted_disk_byte, int count,
336 struct share_check *sc, gfp_t gfp_mask)
337 {
338 struct prelim_ref *ref;
339
340 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
341 return 0;
342
343 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
344 if (!ref)
345 return -ENOMEM;
346
347 ref->root_id = root_id;
348 if (key) {
349 ref->key_for_search = *key;
350 /*
351 * We can often find data backrefs with an offset that is too
352 * large (>= LLONG_MAX, maximum allowed file offset) due to
353 * underflows when subtracting a file's offset with the data
354 * offset of its corresponding extent data item. This can
355 * happen for example in the clone ioctl.
356 * So if we detect such case we set the search key's offset to
357 * zero to make sure we will find the matching file extent item
358 * at add_all_parents(), otherwise we will miss it because the
359 * offset taken form the backref is much larger then the offset
360 * of the file extent item. This can make us scan a very large
361 * number of file extent items, but at least it will not make
362 * us miss any.
363 * This is an ugly workaround for a behaviour that should have
364 * never existed, but it does and a fix for the clone ioctl
365 * would touch a lot of places, cause backwards incompatibility
366 * and would not fix the problem for extents cloned with older
367 * kernels.
368 */
369 if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY &&
370 ref->key_for_search.offset >= LLONG_MAX)
371 ref->key_for_search.offset = 0;
372 } else {
373 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
374 }
375
376 ref->inode_list = NULL;
377 ref->level = level;
378 ref->count = count;
379 ref->parent = parent;
380 ref->wanted_disk_byte = wanted_disk_byte;
381 prelim_ref_insert(fs_info, preftree, ref, sc);
382 return extent_is_shared(sc);
383 }
384
385 /* direct refs use root == 0, key == NULL */
386 static int add_direct_ref(const struct btrfs_fs_info *fs_info,
387 struct preftrees *preftrees, int level, u64 parent,
388 u64 wanted_disk_byte, int count,
389 struct share_check *sc, gfp_t gfp_mask)
390 {
391 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
392 parent, wanted_disk_byte, count, sc, gfp_mask);
393 }
394
395 /* indirect refs use parent == 0 */
396 static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
397 struct preftrees *preftrees, u64 root_id,
398 const struct btrfs_key *key, int level,
399 u64 wanted_disk_byte, int count,
400 struct share_check *sc, gfp_t gfp_mask)
401 {
402 struct preftree *tree = &preftrees->indirect;
403
404 if (!key)
405 tree = &preftrees->indirect_missing_keys;
406 return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
407 wanted_disk_byte, count, sc, gfp_mask);
408 }
409
410 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
411 struct ulist *parents, struct prelim_ref *ref,
412 int level, u64 time_seq, const u64 *extent_item_pos,
413 u64 total_refs, bool ignore_offset)
414 {
415 int ret = 0;
416 int slot;
417 struct extent_buffer *eb;
418 struct btrfs_key key;
419 struct btrfs_key *key_for_search = &ref->key_for_search;
420 struct btrfs_file_extent_item *fi;
421 struct extent_inode_elem *eie = NULL, *old = NULL;
422 u64 disk_byte;
423 u64 wanted_disk_byte = ref->wanted_disk_byte;
424 u64 count = 0;
425
426 if (level != 0) {
427 eb = path->nodes[level];
428 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
429 if (ret < 0)
430 return ret;
431 return 0;
432 }
433
434 /*
435 * We normally enter this function with the path already pointing to
436 * the first item to check. But sometimes, we may enter it with
437 * slot==nritems. In that case, go to the next leaf before we continue.
438 */
439 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
440 if (time_seq == SEQ_LAST)
441 ret = btrfs_next_leaf(root, path);
442 else
443 ret = btrfs_next_old_leaf(root, path, time_seq);
444 }
445
446 while (!ret && count < total_refs) {
447 eb = path->nodes[0];
448 slot = path->slots[0];
449
450 btrfs_item_key_to_cpu(eb, &key, slot);
451
452 if (key.objectid != key_for_search->objectid ||
453 key.type != BTRFS_EXTENT_DATA_KEY)
454 break;
455
456 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
457 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
458
459 if (disk_byte == wanted_disk_byte) {
460 eie = NULL;
461 old = NULL;
462 count++;
463 if (extent_item_pos) {
464 ret = check_extent_in_eb(&key, eb, fi,
465 *extent_item_pos,
466 &eie, ignore_offset);
467 if (ret < 0)
468 break;
469 }
470 if (ret > 0)
471 goto next;
472 ret = ulist_add_merge_ptr(parents, eb->start,
473 eie, (void **)&old, GFP_NOFS);
474 if (ret < 0)
475 break;
476 if (!ret && extent_item_pos) {
477 while (old->next)
478 old = old->next;
479 old->next = eie;
480 }
481 eie = NULL;
482 }
483 next:
484 if (time_seq == SEQ_LAST)
485 ret = btrfs_next_item(root, path);
486 else
487 ret = btrfs_next_old_item(root, path, time_seq);
488 }
489
490 if (ret > 0)
491 ret = 0;
492 else if (ret < 0)
493 free_inode_elem_list(eie);
494 return ret;
495 }
496
497 /*
498 * resolve an indirect backref in the form (root_id, key, level)
499 * to a logical address
500 */
501 static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
502 struct btrfs_path *path, u64 time_seq,
503 struct prelim_ref *ref, struct ulist *parents,
504 const u64 *extent_item_pos, u64 total_refs,
505 bool ignore_offset)
506 {
507 struct btrfs_root *root;
508 struct btrfs_key root_key;
509 struct extent_buffer *eb;
510 int ret = 0;
511 int root_level;
512 int level = ref->level;
513 int index;
514
515 root_key.objectid = ref->root_id;
516 root_key.type = BTRFS_ROOT_ITEM_KEY;
517 root_key.offset = (u64)-1;
518
519 index = srcu_read_lock(&fs_info->subvol_srcu);
520
521 root = btrfs_get_fs_root(fs_info, &root_key, false);
522 if (IS_ERR(root)) {
523 srcu_read_unlock(&fs_info->subvol_srcu, index);
524 ret = PTR_ERR(root);
525 goto out;
526 }
527
528 if (btrfs_is_testing(fs_info)) {
529 srcu_read_unlock(&fs_info->subvol_srcu, index);
530 ret = -ENOENT;
531 goto out;
532 }
533
534 if (path->search_commit_root)
535 root_level = btrfs_header_level(root->commit_root);
536 else if (time_seq == SEQ_LAST)
537 root_level = btrfs_header_level(root->node);
538 else
539 root_level = btrfs_old_root_level(root, time_seq);
540
541 if (root_level + 1 == level) {
542 srcu_read_unlock(&fs_info->subvol_srcu, index);
543 goto out;
544 }
545
546 path->lowest_level = level;
547 if (time_seq == SEQ_LAST)
548 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path,
549 0, 0);
550 else
551 ret = btrfs_search_old_slot(root, &ref->key_for_search, path,
552 time_seq);
553
554 /* root node has been locked, we can release @subvol_srcu safely here */
555 srcu_read_unlock(&fs_info->subvol_srcu, index);
556
557 btrfs_debug(fs_info,
558 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
559 ref->root_id, level, ref->count, ret,
560 ref->key_for_search.objectid, ref->key_for_search.type,
561 ref->key_for_search.offset);
562 if (ret < 0)
563 goto out;
564
565 eb = path->nodes[level];
566 while (!eb) {
567 if (WARN_ON(!level)) {
568 ret = 1;
569 goto out;
570 }
571 level--;
572 eb = path->nodes[level];
573 }
574
575 ret = add_all_parents(root, path, parents, ref, level, time_seq,
576 extent_item_pos, total_refs, ignore_offset);
577 out:
578 path->lowest_level = 0;
579 btrfs_release_path(path);
580 return ret;
581 }
582
583 static struct extent_inode_elem *
584 unode_aux_to_inode_list(struct ulist_node *node)
585 {
586 if (!node)
587 return NULL;
588 return (struct extent_inode_elem *)(uintptr_t)node->aux;
589 }
590
591 /*
592 * We maintain three seperate rbtrees: one for direct refs, one for
593 * indirect refs which have a key, and one for indirect refs which do not
594 * have a key. Each tree does merge on insertion.
595 *
596 * Once all of the references are located, we iterate over the tree of
597 * indirect refs with missing keys. An appropriate key is located and
598 * the ref is moved onto the tree for indirect refs. After all missing
599 * keys are thus located, we iterate over the indirect ref tree, resolve
600 * each reference, and then insert the resolved reference onto the
601 * direct tree (merging there too).
602 *
603 * New backrefs (i.e., for parent nodes) are added to the appropriate
604 * rbtree as they are encountered. The new backrefs are subsequently
605 * resolved as above.
606 */
607 static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
608 struct btrfs_path *path, u64 time_seq,
609 struct preftrees *preftrees,
610 const u64 *extent_item_pos, u64 total_refs,
611 struct share_check *sc, bool ignore_offset)
612 {
613 int err;
614 int ret = 0;
615 struct ulist *parents;
616 struct ulist_node *node;
617 struct ulist_iterator uiter;
618 struct rb_node *rnode;
619
620 parents = ulist_alloc(GFP_NOFS);
621 if (!parents)
622 return -ENOMEM;
623
624 /*
625 * We could trade memory usage for performance here by iterating
626 * the tree, allocating new refs for each insertion, and then
627 * freeing the entire indirect tree when we're done. In some test
628 * cases, the tree can grow quite large (~200k objects).
629 */
630 while ((rnode = rb_first(&preftrees->indirect.root))) {
631 struct prelim_ref *ref;
632
633 ref = rb_entry(rnode, struct prelim_ref, rbnode);
634 if (WARN(ref->parent,
635 "BUG: direct ref found in indirect tree")) {
636 ret = -EINVAL;
637 goto out;
638 }
639
640 rb_erase(&ref->rbnode, &preftrees->indirect.root);
641 preftrees->indirect.count--;
642
643 if (ref->count == 0) {
644 free_pref(ref);
645 continue;
646 }
647
648 if (sc && sc->root_objectid &&
649 ref->root_id != sc->root_objectid) {
650 free_pref(ref);
651 ret = BACKREF_FOUND_SHARED;
652 goto out;
653 }
654 err = resolve_indirect_ref(fs_info, path, time_seq, ref,
655 parents, extent_item_pos,
656 total_refs, ignore_offset);
657 /*
658 * we can only tolerate ENOENT,otherwise,we should catch error
659 * and return directly.
660 */
661 if (err == -ENOENT) {
662 prelim_ref_insert(fs_info, &preftrees->direct, ref,
663 NULL);
664 continue;
665 } else if (err) {
666 free_pref(ref);
667 ret = err;
668 goto out;
669 }
670
671 /* we put the first parent into the ref at hand */
672 ULIST_ITER_INIT(&uiter);
673 node = ulist_next(parents, &uiter);
674 ref->parent = node ? node->val : 0;
675 ref->inode_list = unode_aux_to_inode_list(node);
676
677 /* Add a prelim_ref(s) for any other parent(s). */
678 while ((node = ulist_next(parents, &uiter))) {
679 struct prelim_ref *new_ref;
680
681 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
682 GFP_NOFS);
683 if (!new_ref) {
684 free_pref(ref);
685 ret = -ENOMEM;
686 goto out;
687 }
688 memcpy(new_ref, ref, sizeof(*ref));
689 new_ref->parent = node->val;
690 new_ref->inode_list = unode_aux_to_inode_list(node);
691 prelim_ref_insert(fs_info, &preftrees->direct,
692 new_ref, NULL);
693 }
694
695 /*
696 * Now it's a direct ref, put it in the the direct tree. We must
697 * do this last because the ref could be merged/freed here.
698 */
699 prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL);
700
701 ulist_reinit(parents);
702 cond_resched();
703 }
704 out:
705 ulist_free(parents);
706 return ret;
707 }
708
709 /*
710 * read tree blocks and add keys where required.
711 */
712 static int add_missing_keys(struct btrfs_fs_info *fs_info,
713 struct preftrees *preftrees, bool lock)
714 {
715 struct prelim_ref *ref;
716 struct extent_buffer *eb;
717 struct preftree *tree = &preftrees->indirect_missing_keys;
718 struct rb_node *node;
719
720 while ((node = rb_first(&tree->root))) {
721 ref = rb_entry(node, struct prelim_ref, rbnode);
722 rb_erase(node, &tree->root);
723
724 BUG_ON(ref->parent); /* should not be a direct ref */
725 BUG_ON(ref->key_for_search.type);
726 BUG_ON(!ref->wanted_disk_byte);
727
728 eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0,
729 ref->level - 1, NULL);
730 if (IS_ERR(eb)) {
731 free_pref(ref);
732 return PTR_ERR(eb);
733 } else if (!extent_buffer_uptodate(eb)) {
734 free_pref(ref);
735 free_extent_buffer(eb);
736 return -EIO;
737 }
738 if (lock)
739 btrfs_tree_read_lock(eb);
740 if (btrfs_header_level(eb) == 0)
741 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
742 else
743 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
744 if (lock)
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(&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, path->skip_locking == 0);
1231 if (ret)
1232 goto out;
1233
1234 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.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));
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(&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 if (!path->skip_locking) {
1292 btrfs_tree_read_lock(eb);
1293 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1294 }
1295 ret = find_extent_in_eb(eb, bytenr,
1296 *extent_item_pos, &eie, ignore_offset);
1297 if (!path->skip_locking)
1298 btrfs_tree_read_unlock_blocking(eb);
1299 free_extent_buffer(eb);
1300 if (ret < 0)
1301 goto out;
1302 ref->inode_list = eie;
1303 }
1304 ret = ulist_add_merge_ptr(refs, ref->parent,
1305 ref->inode_list,
1306 (void **)&eie, GFP_NOFS);
1307 if (ret < 0)
1308 goto out;
1309 if (!ret && extent_item_pos) {
1310 /*
1311 * we've recorded that parent, so we must extend
1312 * its inode list here
1313 */
1314 BUG_ON(!eie);
1315 while (eie->next)
1316 eie = eie->next;
1317 eie->next = ref->inode_list;
1318 }
1319 eie = NULL;
1320 }
1321 cond_resched();
1322 }
1323
1324 out:
1325 btrfs_free_path(path);
1326
1327 prelim_release(&preftrees.direct);
1328 prelim_release(&preftrees.indirect);
1329 prelim_release(&preftrees.indirect_missing_keys);
1330
1331 if (ret < 0)
1332 free_inode_elem_list(eie);
1333 return ret;
1334 }
1335
1336 static void free_leaf_list(struct ulist *blocks)
1337 {
1338 struct ulist_node *node = NULL;
1339 struct extent_inode_elem *eie;
1340 struct ulist_iterator uiter;
1341
1342 ULIST_ITER_INIT(&uiter);
1343 while ((node = ulist_next(blocks, &uiter))) {
1344 if (!node->aux)
1345 continue;
1346 eie = unode_aux_to_inode_list(node);
1347 free_inode_elem_list(eie);
1348 node->aux = 0;
1349 }
1350
1351 ulist_free(blocks);
1352 }
1353
1354 /*
1355 * Finds all leafs with a reference to the specified combination of bytenr and
1356 * offset. key_list_head will point to a list of corresponding keys (caller must
1357 * free each list element). The leafs will be stored in the leafs ulist, which
1358 * must be freed with ulist_free.
1359 *
1360 * returns 0 on success, <0 on error
1361 */
1362 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1363 struct btrfs_fs_info *fs_info, u64 bytenr,
1364 u64 time_seq, struct ulist **leafs,
1365 const u64 *extent_item_pos, bool ignore_offset)
1366 {
1367 int ret;
1368
1369 *leafs = ulist_alloc(GFP_NOFS);
1370 if (!*leafs)
1371 return -ENOMEM;
1372
1373 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1374 *leafs, NULL, extent_item_pos, NULL, ignore_offset);
1375 if (ret < 0 && ret != -ENOENT) {
1376 free_leaf_list(*leafs);
1377 return ret;
1378 }
1379
1380 return 0;
1381 }
1382
1383 /*
1384 * walk all backrefs for a given extent to find all roots that reference this
1385 * extent. Walking a backref means finding all extents that reference this
1386 * extent and in turn walk the backrefs of those, too. Naturally this is a
1387 * recursive process, but here it is implemented in an iterative fashion: We
1388 * find all referencing extents for the extent in question and put them on a
1389 * list. In turn, we find all referencing extents for those, further appending
1390 * to the list. The way we iterate the list allows adding more elements after
1391 * the current while iterating. The process stops when we reach the end of the
1392 * list. Found roots are added to the roots list.
1393 *
1394 * returns 0 on success, < 0 on error.
1395 */
1396 static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
1397 struct btrfs_fs_info *fs_info, u64 bytenr,
1398 u64 time_seq, struct ulist **roots,
1399 bool ignore_offset)
1400 {
1401 struct ulist *tmp;
1402 struct ulist_node *node = NULL;
1403 struct ulist_iterator uiter;
1404 int ret;
1405
1406 tmp = ulist_alloc(GFP_NOFS);
1407 if (!tmp)
1408 return -ENOMEM;
1409 *roots = ulist_alloc(GFP_NOFS);
1410 if (!*roots) {
1411 ulist_free(tmp);
1412 return -ENOMEM;
1413 }
1414
1415 ULIST_ITER_INIT(&uiter);
1416 while (1) {
1417 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
1418 tmp, *roots, NULL, NULL, ignore_offset);
1419 if (ret < 0 && ret != -ENOENT) {
1420 ulist_free(tmp);
1421 ulist_free(*roots);
1422 return ret;
1423 }
1424 node = ulist_next(tmp, &uiter);
1425 if (!node)
1426 break;
1427 bytenr = node->val;
1428 cond_resched();
1429 }
1430
1431 ulist_free(tmp);
1432 return 0;
1433 }
1434
1435 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1436 struct btrfs_fs_info *fs_info, u64 bytenr,
1437 u64 time_seq, struct ulist **roots,
1438 bool ignore_offset)
1439 {
1440 int ret;
1441
1442 if (!trans)
1443 down_read(&fs_info->commit_root_sem);
1444 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr,
1445 time_seq, roots, ignore_offset);
1446 if (!trans)
1447 up_read(&fs_info->commit_root_sem);
1448 return ret;
1449 }
1450
1451 /**
1452 * btrfs_check_shared - tell us whether an extent is shared
1453 *
1454 * btrfs_check_shared uses the backref walking code but will short
1455 * circuit as soon as it finds a root or inode that doesn't match the
1456 * one passed in. This provides a significant performance benefit for
1457 * callers (such as fiemap) which want to know whether the extent is
1458 * shared but do not need a ref count.
1459 *
1460 * This attempts to attach to the running transaction in order to account for
1461 * delayed refs, but continues on even when no running transaction exists.
1462 *
1463 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
1464 */
1465 int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
1466 {
1467 struct btrfs_fs_info *fs_info = root->fs_info;
1468 struct btrfs_trans_handle *trans;
1469 struct ulist *tmp = NULL;
1470 struct ulist *roots = NULL;
1471 struct ulist_iterator uiter;
1472 struct ulist_node *node;
1473 struct seq_list elem = SEQ_LIST_INIT(elem);
1474 int ret = 0;
1475 struct share_check shared = {
1476 .root_objectid = root->objectid,
1477 .inum = inum,
1478 .share_count = 0,
1479 };
1480
1481 tmp = ulist_alloc(GFP_NOFS);
1482 roots = ulist_alloc(GFP_NOFS);
1483 if (!tmp || !roots) {
1484 ret = -ENOMEM;
1485 goto out;
1486 }
1487
1488 trans = btrfs_join_transaction_nostart(root);
1489 if (IS_ERR(trans)) {
1490 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
1491 ret = PTR_ERR(trans);
1492 goto out;
1493 }
1494 trans = NULL;
1495 down_read(&fs_info->commit_root_sem);
1496 } else {
1497 btrfs_get_tree_mod_seq(fs_info, &elem);
1498 }
1499
1500 ULIST_ITER_INIT(&uiter);
1501 while (1) {
1502 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
1503 roots, NULL, &shared, false);
1504 if (ret == BACKREF_FOUND_SHARED) {
1505 /* this is the only condition under which we return 1 */
1506 ret = 1;
1507 break;
1508 }
1509 if (ret < 0 && ret != -ENOENT)
1510 break;
1511 ret = 0;
1512 node = ulist_next(tmp, &uiter);
1513 if (!node)
1514 break;
1515 bytenr = node->val;
1516 shared.share_count = 0;
1517 cond_resched();
1518 }
1519
1520 if (trans) {
1521 btrfs_put_tree_mod_seq(fs_info, &elem);
1522 btrfs_end_transaction(trans);
1523 } else {
1524 up_read(&fs_info->commit_root_sem);
1525 }
1526 out:
1527 ulist_free(tmp);
1528 ulist_free(roots);
1529 return ret;
1530 }
1531
1532 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1533 u64 start_off, struct btrfs_path *path,
1534 struct btrfs_inode_extref **ret_extref,
1535 u64 *found_off)
1536 {
1537 int ret, slot;
1538 struct btrfs_key key;
1539 struct btrfs_key found_key;
1540 struct btrfs_inode_extref *extref;
1541 const struct extent_buffer *leaf;
1542 unsigned long ptr;
1543
1544 key.objectid = inode_objectid;
1545 key.type = BTRFS_INODE_EXTREF_KEY;
1546 key.offset = start_off;
1547
1548 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1549 if (ret < 0)
1550 return ret;
1551
1552 while (1) {
1553 leaf = path->nodes[0];
1554 slot = path->slots[0];
1555 if (slot >= btrfs_header_nritems(leaf)) {
1556 /*
1557 * If the item at offset is not found,
1558 * btrfs_search_slot will point us to the slot
1559 * where it should be inserted. In our case
1560 * that will be the slot directly before the
1561 * next INODE_REF_KEY_V2 item. In the case
1562 * that we're pointing to the last slot in a
1563 * leaf, we must move one leaf over.
1564 */
1565 ret = btrfs_next_leaf(root, path);
1566 if (ret) {
1567 if (ret >= 1)
1568 ret = -ENOENT;
1569 break;
1570 }
1571 continue;
1572 }
1573
1574 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1575
1576 /*
1577 * Check that we're still looking at an extended ref key for
1578 * this particular objectid. If we have different
1579 * objectid or type then there are no more to be found
1580 * in the tree and we can exit.
1581 */
1582 ret = -ENOENT;
1583 if (found_key.objectid != inode_objectid)
1584 break;
1585 if (found_key.type != BTRFS_INODE_EXTREF_KEY)
1586 break;
1587
1588 ret = 0;
1589 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1590 extref = (struct btrfs_inode_extref *)ptr;
1591 *ret_extref = extref;
1592 if (found_off)
1593 *found_off = found_key.offset;
1594 break;
1595 }
1596
1597 return ret;
1598 }
1599
1600 /*
1601 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1602 * Elements of the path are separated by '/' and the path is guaranteed to be
1603 * 0-terminated. the path is only given within the current file system.
1604 * Therefore, it never starts with a '/'. the caller is responsible to provide
1605 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1606 * the start point of the resulting string is returned. this pointer is within
1607 * dest, normally.
1608 * in case the path buffer would overflow, the pointer is decremented further
1609 * as if output was written to the buffer, though no more output is actually
1610 * generated. that way, the caller can determine how much space would be
1611 * required for the path to fit into the buffer. in that case, the returned
1612 * value will be smaller than dest. callers must check this!
1613 */
1614 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1615 u32 name_len, unsigned long name_off,
1616 struct extent_buffer *eb_in, u64 parent,
1617 char *dest, u32 size)
1618 {
1619 int slot;
1620 u64 next_inum;
1621 int ret;
1622 s64 bytes_left = ((s64)size) - 1;
1623 struct extent_buffer *eb = eb_in;
1624 struct btrfs_key found_key;
1625 int leave_spinning = path->leave_spinning;
1626 struct btrfs_inode_ref *iref;
1627
1628 if (bytes_left >= 0)
1629 dest[bytes_left] = '\0';
1630
1631 path->leave_spinning = 1;
1632 while (1) {
1633 bytes_left -= name_len;
1634 if (bytes_left >= 0)
1635 read_extent_buffer(eb, dest + bytes_left,
1636 name_off, name_len);
1637 if (eb != eb_in) {
1638 if (!path->skip_locking)
1639 btrfs_tree_read_unlock_blocking(eb);
1640 free_extent_buffer(eb);
1641 }
1642 ret = btrfs_find_item(fs_root, path, parent, 0,
1643 BTRFS_INODE_REF_KEY, &found_key);
1644 if (ret > 0)
1645 ret = -ENOENT;
1646 if (ret)
1647 break;
1648
1649 next_inum = found_key.offset;
1650
1651 /* regular exit ahead */
1652 if (parent == next_inum)
1653 break;
1654
1655 slot = path->slots[0];
1656 eb = path->nodes[0];
1657 /* make sure we can use eb after releasing the path */
1658 if (eb != eb_in) {
1659 if (!path->skip_locking)
1660 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1661 path->nodes[0] = NULL;
1662 path->locks[0] = 0;
1663 }
1664 btrfs_release_path(path);
1665 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1666
1667 name_len = btrfs_inode_ref_name_len(eb, iref);
1668 name_off = (unsigned long)(iref + 1);
1669
1670 parent = next_inum;
1671 --bytes_left;
1672 if (bytes_left >= 0)
1673 dest[bytes_left] = '/';
1674 }
1675
1676 btrfs_release_path(path);
1677 path->leave_spinning = leave_spinning;
1678
1679 if (ret)
1680 return ERR_PTR(ret);
1681
1682 return dest + bytes_left;
1683 }
1684
1685 /*
1686 * this makes the path point to (logical EXTENT_ITEM *)
1687 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1688 * tree blocks and <0 on error.
1689 */
1690 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1691 struct btrfs_path *path, struct btrfs_key *found_key,
1692 u64 *flags_ret)
1693 {
1694 int ret;
1695 u64 flags;
1696 u64 size = 0;
1697 u32 item_size;
1698 const struct extent_buffer *eb;
1699 struct btrfs_extent_item *ei;
1700 struct btrfs_key key;
1701
1702 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1703 key.type = BTRFS_METADATA_ITEM_KEY;
1704 else
1705 key.type = BTRFS_EXTENT_ITEM_KEY;
1706 key.objectid = logical;
1707 key.offset = (u64)-1;
1708
1709 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1710 if (ret < 0)
1711 return ret;
1712
1713 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1714 if (ret) {
1715 if (ret > 0)
1716 ret = -ENOENT;
1717 return ret;
1718 }
1719 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1720 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1721 size = fs_info->nodesize;
1722 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1723 size = found_key->offset;
1724
1725 if (found_key->objectid > logical ||
1726 found_key->objectid + size <= logical) {
1727 btrfs_debug(fs_info,
1728 "logical %llu is not within any extent", logical);
1729 return -ENOENT;
1730 }
1731
1732 eb = path->nodes[0];
1733 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1734 BUG_ON(item_size < sizeof(*ei));
1735
1736 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1737 flags = btrfs_extent_flags(eb, ei);
1738
1739 btrfs_debug(fs_info,
1740 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
1741 logical, logical - found_key->objectid, found_key->objectid,
1742 found_key->offset, flags, item_size);
1743
1744 WARN_ON(!flags_ret);
1745 if (flags_ret) {
1746 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1747 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1748 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1749 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1750 else
1751 BUG_ON(1);
1752 return 0;
1753 }
1754
1755 return -EIO;
1756 }
1757
1758 /*
1759 * helper function to iterate extent inline refs. ptr must point to a 0 value
1760 * for the first call and may be modified. it is used to track state.
1761 * if more refs exist, 0 is returned and the next call to
1762 * get_extent_inline_ref must pass the modified ptr parameter to get the
1763 * next ref. after the last ref was processed, 1 is returned.
1764 * returns <0 on error
1765 */
1766 static int get_extent_inline_ref(unsigned long *ptr,
1767 const struct extent_buffer *eb,
1768 const struct btrfs_key *key,
1769 const struct btrfs_extent_item *ei,
1770 u32 item_size,
1771 struct btrfs_extent_inline_ref **out_eiref,
1772 int *out_type)
1773 {
1774 unsigned long end;
1775 u64 flags;
1776 struct btrfs_tree_block_info *info;
1777
1778 if (!*ptr) {
1779 /* first call */
1780 flags = btrfs_extent_flags(eb, ei);
1781 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1782 if (key->type == BTRFS_METADATA_ITEM_KEY) {
1783 /* a skinny metadata extent */
1784 *out_eiref =
1785 (struct btrfs_extent_inline_ref *)(ei + 1);
1786 } else {
1787 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
1788 info = (struct btrfs_tree_block_info *)(ei + 1);
1789 *out_eiref =
1790 (struct btrfs_extent_inline_ref *)(info + 1);
1791 }
1792 } else {
1793 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1794 }
1795 *ptr = (unsigned long)*out_eiref;
1796 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
1797 return -ENOENT;
1798 }
1799
1800 end = (unsigned long)ei + item_size;
1801 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
1802 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
1803 BTRFS_REF_TYPE_ANY);
1804 if (*out_type == BTRFS_REF_TYPE_INVALID)
1805 return -EUCLEAN;
1806
1807 *ptr += btrfs_extent_inline_ref_size(*out_type);
1808 WARN_ON(*ptr > end);
1809 if (*ptr == end)
1810 return 1; /* last */
1811
1812 return 0;
1813 }
1814
1815 /*
1816 * reads the tree block backref for an extent. tree level and root are returned
1817 * through out_level and out_root. ptr must point to a 0 value for the first
1818 * call and may be modified (see get_extent_inline_ref comment).
1819 * returns 0 if data was provided, 1 if there was no more data to provide or
1820 * <0 on error.
1821 */
1822 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1823 struct btrfs_key *key, struct btrfs_extent_item *ei,
1824 u32 item_size, u64 *out_root, u8 *out_level)
1825 {
1826 int ret;
1827 int type;
1828 struct btrfs_extent_inline_ref *eiref;
1829
1830 if (*ptr == (unsigned long)-1)
1831 return 1;
1832
1833 while (1) {
1834 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size,
1835 &eiref, &type);
1836 if (ret < 0)
1837 return ret;
1838
1839 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1840 type == BTRFS_SHARED_BLOCK_REF_KEY)
1841 break;
1842
1843 if (ret == 1)
1844 return 1;
1845 }
1846
1847 /* we can treat both ref types equally here */
1848 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1849
1850 if (key->type == BTRFS_EXTENT_ITEM_KEY) {
1851 struct btrfs_tree_block_info *info;
1852
1853 info = (struct btrfs_tree_block_info *)(ei + 1);
1854 *out_level = btrfs_tree_block_level(eb, info);
1855 } else {
1856 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
1857 *out_level = (u8)key->offset;
1858 }
1859
1860 if (ret == 1)
1861 *ptr = (unsigned long)-1;
1862
1863 return 0;
1864 }
1865
1866 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
1867 struct extent_inode_elem *inode_list,
1868 u64 root, u64 extent_item_objectid,
1869 iterate_extent_inodes_t *iterate, void *ctx)
1870 {
1871 struct extent_inode_elem *eie;
1872 int ret = 0;
1873
1874 for (eie = inode_list; eie; eie = eie->next) {
1875 btrfs_debug(fs_info,
1876 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
1877 extent_item_objectid, eie->inum,
1878 eie->offset, root);
1879 ret = iterate(eie->inum, eie->offset, root, ctx);
1880 if (ret) {
1881 btrfs_debug(fs_info,
1882 "stopping iteration for %llu due to ret=%d",
1883 extent_item_objectid, ret);
1884 break;
1885 }
1886 }
1887
1888 return ret;
1889 }
1890
1891 /*
1892 * calls iterate() for every inode that references the extent identified by
1893 * the given parameters.
1894 * when the iterator function returns a non-zero value, iteration stops.
1895 */
1896 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1897 u64 extent_item_objectid, u64 extent_item_pos,
1898 int search_commit_root,
1899 iterate_extent_inodes_t *iterate, void *ctx,
1900 bool ignore_offset)
1901 {
1902 int ret;
1903 struct btrfs_trans_handle *trans = NULL;
1904 struct ulist *refs = NULL;
1905 struct ulist *roots = NULL;
1906 struct ulist_node *ref_node = NULL;
1907 struct ulist_node *root_node = NULL;
1908 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
1909 struct ulist_iterator ref_uiter;
1910 struct ulist_iterator root_uiter;
1911
1912 btrfs_debug(fs_info, "resolving all inodes for extent %llu",
1913 extent_item_objectid);
1914
1915 if (!search_commit_root) {
1916 trans = btrfs_attach_transaction(fs_info->extent_root);
1917 if (IS_ERR(trans)) {
1918 if (PTR_ERR(trans) != -ENOENT &&
1919 PTR_ERR(trans) != -EROFS)
1920 return PTR_ERR(trans);
1921 trans = NULL;
1922 }
1923 }
1924
1925 if (trans)
1926 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1927 else
1928 down_read(&fs_info->commit_root_sem);
1929
1930 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1931 tree_mod_seq_elem.seq, &refs,
1932 &extent_item_pos, ignore_offset);
1933 if (ret)
1934 goto out;
1935
1936 ULIST_ITER_INIT(&ref_uiter);
1937 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1938 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val,
1939 tree_mod_seq_elem.seq, &roots,
1940 ignore_offset);
1941 if (ret)
1942 break;
1943 ULIST_ITER_INIT(&root_uiter);
1944 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1945 btrfs_debug(fs_info,
1946 "root %llu references leaf %llu, data list %#llx",
1947 root_node->val, ref_node->val,
1948 ref_node->aux);
1949 ret = iterate_leaf_refs(fs_info,
1950 (struct extent_inode_elem *)
1951 (uintptr_t)ref_node->aux,
1952 root_node->val,
1953 extent_item_objectid,
1954 iterate, ctx);
1955 }
1956 ulist_free(roots);
1957 }
1958
1959 free_leaf_list(refs);
1960 out:
1961 if (trans) {
1962 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1963 btrfs_end_transaction(trans);
1964 } else {
1965 up_read(&fs_info->commit_root_sem);
1966 }
1967
1968 return ret;
1969 }
1970
1971 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1972 struct btrfs_path *path,
1973 iterate_extent_inodes_t *iterate, void *ctx,
1974 bool ignore_offset)
1975 {
1976 int ret;
1977 u64 extent_item_pos;
1978 u64 flags = 0;
1979 struct btrfs_key found_key;
1980 int search_commit_root = path->search_commit_root;
1981
1982 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1983 btrfs_release_path(path);
1984 if (ret < 0)
1985 return ret;
1986 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1987 return -EINVAL;
1988
1989 extent_item_pos = logical - found_key.objectid;
1990 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1991 extent_item_pos, search_commit_root,
1992 iterate, ctx, ignore_offset);
1993
1994 return ret;
1995 }
1996
1997 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1998 struct extent_buffer *eb, void *ctx);
1999
2000 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
2001 struct btrfs_path *path,
2002 iterate_irefs_t *iterate, void *ctx)
2003 {
2004 int ret = 0;
2005 int slot;
2006 u32 cur;
2007 u32 len;
2008 u32 name_len;
2009 u64 parent = 0;
2010 int found = 0;
2011 struct extent_buffer *eb;
2012 struct btrfs_item *item;
2013 struct btrfs_inode_ref *iref;
2014 struct btrfs_key found_key;
2015
2016 while (!ret) {
2017 ret = btrfs_find_item(fs_root, path, inum,
2018 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
2019 &found_key);
2020
2021 if (ret < 0)
2022 break;
2023 if (ret) {
2024 ret = found ? 0 : -ENOENT;
2025 break;
2026 }
2027 ++found;
2028
2029 parent = found_key.offset;
2030 slot = path->slots[0];
2031 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2032 if (!eb) {
2033 ret = -ENOMEM;
2034 break;
2035 }
2036 extent_buffer_get(eb);
2037 btrfs_tree_read_lock(eb);
2038 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2039 btrfs_release_path(path);
2040
2041 item = btrfs_item_nr(slot);
2042 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
2043
2044 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
2045 name_len = btrfs_inode_ref_name_len(eb, iref);
2046 /* path must be released before calling iterate()! */
2047 btrfs_debug(fs_root->fs_info,
2048 "following ref at offset %u for inode %llu in tree %llu",
2049 cur, found_key.objectid, fs_root->objectid);
2050 ret = iterate(parent, name_len,
2051 (unsigned long)(iref + 1), eb, ctx);
2052 if (ret)
2053 break;
2054 len = sizeof(*iref) + name_len;
2055 iref = (struct btrfs_inode_ref *)((char *)iref + len);
2056 }
2057 btrfs_tree_read_unlock_blocking(eb);
2058 free_extent_buffer(eb);
2059 }
2060
2061 btrfs_release_path(path);
2062
2063 return ret;
2064 }
2065
2066 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
2067 struct btrfs_path *path,
2068 iterate_irefs_t *iterate, void *ctx)
2069 {
2070 int ret;
2071 int slot;
2072 u64 offset = 0;
2073 u64 parent;
2074 int found = 0;
2075 struct extent_buffer *eb;
2076 struct btrfs_inode_extref *extref;
2077 u32 item_size;
2078 u32 cur_offset;
2079 unsigned long ptr;
2080
2081 while (1) {
2082 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
2083 &offset);
2084 if (ret < 0)
2085 break;
2086 if (ret) {
2087 ret = found ? 0 : -ENOENT;
2088 break;
2089 }
2090 ++found;
2091
2092 slot = path->slots[0];
2093 eb = btrfs_clone_extent_buffer(path->nodes[0]);
2094 if (!eb) {
2095 ret = -ENOMEM;
2096 break;
2097 }
2098 extent_buffer_get(eb);
2099
2100 btrfs_tree_read_lock(eb);
2101 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
2102 btrfs_release_path(path);
2103
2104 item_size = btrfs_item_size_nr(eb, slot);
2105 ptr = btrfs_item_ptr_offset(eb, slot);
2106 cur_offset = 0;
2107
2108 while (cur_offset < item_size) {
2109 u32 name_len;
2110
2111 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
2112 parent = btrfs_inode_extref_parent(eb, extref);
2113 name_len = btrfs_inode_extref_name_len(eb, extref);
2114 ret = iterate(parent, name_len,
2115 (unsigned long)&extref->name, eb, ctx);
2116 if (ret)
2117 break;
2118
2119 cur_offset += btrfs_inode_extref_name_len(eb, extref);
2120 cur_offset += sizeof(*extref);
2121 }
2122 btrfs_tree_read_unlock_blocking(eb);
2123 free_extent_buffer(eb);
2124
2125 offset++;
2126 }
2127
2128 btrfs_release_path(path);
2129
2130 return ret;
2131 }
2132
2133 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
2134 struct btrfs_path *path, iterate_irefs_t *iterate,
2135 void *ctx)
2136 {
2137 int ret;
2138 int found_refs = 0;
2139
2140 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
2141 if (!ret)
2142 ++found_refs;
2143 else if (ret != -ENOENT)
2144 return ret;
2145
2146 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
2147 if (ret == -ENOENT && found_refs)
2148 return 0;
2149
2150 return ret;
2151 }
2152
2153 /*
2154 * returns 0 if the path could be dumped (probably truncated)
2155 * returns <0 in case of an error
2156 */
2157 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
2158 struct extent_buffer *eb, void *ctx)
2159 {
2160 struct inode_fs_paths *ipath = ctx;
2161 char *fspath;
2162 char *fspath_min;
2163 int i = ipath->fspath->elem_cnt;
2164 const int s_ptr = sizeof(char *);
2165 u32 bytes_left;
2166
2167 bytes_left = ipath->fspath->bytes_left > s_ptr ?
2168 ipath->fspath->bytes_left - s_ptr : 0;
2169
2170 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
2171 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
2172 name_off, eb, inum, fspath_min, bytes_left);
2173 if (IS_ERR(fspath))
2174 return PTR_ERR(fspath);
2175
2176 if (fspath > fspath_min) {
2177 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
2178 ++ipath->fspath->elem_cnt;
2179 ipath->fspath->bytes_left = fspath - fspath_min;
2180 } else {
2181 ++ipath->fspath->elem_missed;
2182 ipath->fspath->bytes_missing += fspath_min - fspath;
2183 ipath->fspath->bytes_left = 0;
2184 }
2185
2186 return 0;
2187 }
2188
2189 /*
2190 * this dumps all file system paths to the inode into the ipath struct, provided
2191 * is has been created large enough. each path is zero-terminated and accessed
2192 * from ipath->fspath->val[i].
2193 * when it returns, there are ipath->fspath->elem_cnt number of paths available
2194 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
2195 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
2196 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
2197 * have been needed to return all paths.
2198 */
2199 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
2200 {
2201 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
2202 inode_to_path, ipath);
2203 }
2204
2205 struct btrfs_data_container *init_data_container(u32 total_bytes)
2206 {
2207 struct btrfs_data_container *data;
2208 size_t alloc_bytes;
2209
2210 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
2211 data = kvmalloc(alloc_bytes, GFP_KERNEL);
2212 if (!data)
2213 return ERR_PTR(-ENOMEM);
2214
2215 if (total_bytes >= sizeof(*data)) {
2216 data->bytes_left = total_bytes - sizeof(*data);
2217 data->bytes_missing = 0;
2218 } else {
2219 data->bytes_missing = sizeof(*data) - total_bytes;
2220 data->bytes_left = 0;
2221 }
2222
2223 data->elem_cnt = 0;
2224 data->elem_missed = 0;
2225
2226 return data;
2227 }
2228
2229 /*
2230 * allocates space to return multiple file system paths for an inode.
2231 * total_bytes to allocate are passed, note that space usable for actual path
2232 * information will be total_bytes - sizeof(struct inode_fs_paths).
2233 * the returned pointer must be freed with free_ipath() in the end.
2234 */
2235 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
2236 struct btrfs_path *path)
2237 {
2238 struct inode_fs_paths *ifp;
2239 struct btrfs_data_container *fspath;
2240
2241 fspath = init_data_container(total_bytes);
2242 if (IS_ERR(fspath))
2243 return ERR_CAST(fspath);
2244
2245 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
2246 if (!ifp) {
2247 kvfree(fspath);
2248 return ERR_PTR(-ENOMEM);
2249 }
2250
2251 ifp->btrfs_path = path;
2252 ifp->fspath = fspath;
2253 ifp->fs_root = fs_root;
2254
2255 return ifp;
2256 }
2257
2258 void free_ipath(struct inode_fs_paths *ipath)
2259 {
2260 if (!ipath)
2261 return;
2262 kvfree(ipath->fspath);
2263 kfree(ipath);
2264 }
Linux with added FPC-III support