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Btrfs: don't store NULL byte in symlink extents
[deliverable/linux.git] / fs / btrfs / backref.c
1 /*
2 * Copyright (C) 2011 STRATO. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/vmalloc.h>
20 #include "ctree.h"
21 #include "disk-io.h"
22 #include "backref.h"
23 #include "ulist.h"
24 #include "transaction.h"
25 #include "delayed-ref.h"
26 #include "locking.h"
27
28 struct extent_inode_elem {
29 u64 inum;
30 u64 offset;
31 struct extent_inode_elem *next;
32 };
33
34 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
35 struct btrfs_file_extent_item *fi,
36 u64 extent_item_pos,
37 struct extent_inode_elem **eie)
38 {
39 u64 offset = 0;
40 struct extent_inode_elem *e;
41
42 if (!btrfs_file_extent_compression(eb, fi) &&
43 !btrfs_file_extent_encryption(eb, fi) &&
44 !btrfs_file_extent_other_encoding(eb, fi)) {
45 u64 data_offset;
46 u64 data_len;
47
48 data_offset = btrfs_file_extent_offset(eb, fi);
49 data_len = btrfs_file_extent_num_bytes(eb, fi);
50
51 if (extent_item_pos < data_offset ||
52 extent_item_pos >= data_offset + data_len)
53 return 1;
54 offset = extent_item_pos - data_offset;
55 }
56
57 e = kmalloc(sizeof(*e), GFP_NOFS);
58 if (!e)
59 return -ENOMEM;
60
61 e->next = *eie;
62 e->inum = key->objectid;
63 e->offset = key->offset + offset;
64 *eie = e;
65
66 return 0;
67 }
68
69 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
70 u64 extent_item_pos,
71 struct extent_inode_elem **eie)
72 {
73 u64 disk_byte;
74 struct btrfs_key key;
75 struct btrfs_file_extent_item *fi;
76 int slot;
77 int nritems;
78 int extent_type;
79 int ret;
80
81 /*
82 * from the shared data ref, we only have the leaf but we need
83 * the key. thus, we must look into all items and see that we
84 * find one (some) with a reference to our extent item.
85 */
86 nritems = btrfs_header_nritems(eb);
87 for (slot = 0; slot < nritems; ++slot) {
88 btrfs_item_key_to_cpu(eb, &key, slot);
89 if (key.type != BTRFS_EXTENT_DATA_KEY)
90 continue;
91 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
92 extent_type = btrfs_file_extent_type(eb, fi);
93 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
94 continue;
95 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
96 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
97 if (disk_byte != wanted_disk_byte)
98 continue;
99
100 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
101 if (ret < 0)
102 return ret;
103 }
104
105 return 0;
106 }
107
108 /*
109 * this structure records all encountered refs on the way up to the root
110 */
111 struct __prelim_ref {
112 struct list_head list;
113 u64 root_id;
114 struct btrfs_key key_for_search;
115 int level;
116 int count;
117 struct extent_inode_elem *inode_list;
118 u64 parent;
119 u64 wanted_disk_byte;
120 };
121
122 static struct kmem_cache *btrfs_prelim_ref_cache;
123
124 int __init btrfs_prelim_ref_init(void)
125 {
126 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
127 sizeof(struct __prelim_ref),
128 0,
129 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
130 NULL);
131 if (!btrfs_prelim_ref_cache)
132 return -ENOMEM;
133 return 0;
134 }
135
136 void btrfs_prelim_ref_exit(void)
137 {
138 if (btrfs_prelim_ref_cache)
139 kmem_cache_destroy(btrfs_prelim_ref_cache);
140 }
141
142 /*
143 * the rules for all callers of this function are:
144 * - obtaining the parent is the goal
145 * - if you add a key, you must know that it is a correct key
146 * - if you cannot add the parent or a correct key, then we will look into the
147 * block later to set a correct key
148 *
149 * delayed refs
150 * ============
151 * backref type | shared | indirect | shared | indirect
152 * information | tree | tree | data | data
153 * --------------------+--------+----------+--------+----------
154 * parent logical | y | - | - | -
155 * key to resolve | - | y | y | y
156 * tree block logical | - | - | - | -
157 * root for resolving | y | y | y | y
158 *
159 * - column 1: we've the parent -> done
160 * - column 2, 3, 4: we use the key to find the parent
161 *
162 * on disk refs (inline or keyed)
163 * ==============================
164 * backref type | shared | indirect | shared | indirect
165 * information | tree | tree | data | data
166 * --------------------+--------+----------+--------+----------
167 * parent logical | y | - | y | -
168 * key to resolve | - | - | - | y
169 * tree block logical | y | y | y | y
170 * root for resolving | - | y | y | y
171 *
172 * - column 1, 3: we've the parent -> done
173 * - column 2: we take the first key from the block to find the parent
174 * (see __add_missing_keys)
175 * - column 4: we use the key to find the parent
176 *
177 * additional information that's available but not required to find the parent
178 * block might help in merging entries to gain some speed.
179 */
180
181 static int __add_prelim_ref(struct list_head *head, u64 root_id,
182 struct btrfs_key *key, int level,
183 u64 parent, u64 wanted_disk_byte, int count,
184 gfp_t gfp_mask)
185 {
186 struct __prelim_ref *ref;
187
188 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
189 if (!ref)
190 return -ENOMEM;
191
192 ref->root_id = root_id;
193 if (key)
194 ref->key_for_search = *key;
195 else
196 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
197
198 ref->inode_list = NULL;
199 ref->level = level;
200 ref->count = count;
201 ref->parent = parent;
202 ref->wanted_disk_byte = wanted_disk_byte;
203 list_add_tail(&ref->list, head);
204
205 return 0;
206 }
207
208 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
209 struct ulist *parents, int level,
210 struct btrfs_key *key_for_search, u64 time_seq,
211 u64 wanted_disk_byte,
212 const u64 *extent_item_pos)
213 {
214 int ret = 0;
215 int slot;
216 struct extent_buffer *eb;
217 struct btrfs_key key;
218 struct btrfs_file_extent_item *fi;
219 struct extent_inode_elem *eie = NULL, *old = NULL;
220 u64 disk_byte;
221
222 if (level != 0) {
223 eb = path->nodes[level];
224 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
225 if (ret < 0)
226 return ret;
227 return 0;
228 }
229
230 /*
231 * We normally enter this function with the path already pointing to
232 * the first item to check. But sometimes, we may enter it with
233 * slot==nritems. In that case, go to the next leaf before we continue.
234 */
235 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
236 ret = btrfs_next_old_leaf(root, path, time_seq);
237
238 while (!ret) {
239 eb = path->nodes[0];
240 slot = path->slots[0];
241
242 btrfs_item_key_to_cpu(eb, &key, slot);
243
244 if (key.objectid != key_for_search->objectid ||
245 key.type != BTRFS_EXTENT_DATA_KEY)
246 break;
247
248 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
249 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
250
251 if (disk_byte == wanted_disk_byte) {
252 eie = NULL;
253 old = NULL;
254 if (extent_item_pos) {
255 ret = check_extent_in_eb(&key, eb, fi,
256 *extent_item_pos,
257 &eie);
258 if (ret < 0)
259 break;
260 }
261 if (ret > 0)
262 goto next;
263 ret = ulist_add_merge(parents, eb->start,
264 (uintptr_t)eie,
265 (u64 *)&old, GFP_NOFS);
266 if (ret < 0)
267 break;
268 if (!ret && extent_item_pos) {
269 while (old->next)
270 old = old->next;
271 old->next = eie;
272 }
273 }
274 next:
275 ret = btrfs_next_old_item(root, path, time_seq);
276 }
277
278 if (ret > 0)
279 ret = 0;
280 return ret;
281 }
282
283 /*
284 * resolve an indirect backref in the form (root_id, key, level)
285 * to a logical address
286 */
287 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
288 struct btrfs_path *path, u64 time_seq,
289 struct __prelim_ref *ref,
290 struct ulist *parents,
291 const u64 *extent_item_pos)
292 {
293 struct btrfs_root *root;
294 struct btrfs_key root_key;
295 struct extent_buffer *eb;
296 int ret = 0;
297 int root_level;
298 int level = ref->level;
299
300 root_key.objectid = ref->root_id;
301 root_key.type = BTRFS_ROOT_ITEM_KEY;
302 root_key.offset = (u64)-1;
303 root = btrfs_read_fs_root_no_name(fs_info, &root_key);
304 if (IS_ERR(root)) {
305 ret = PTR_ERR(root);
306 goto out;
307 }
308
309 root_level = btrfs_old_root_level(root, time_seq);
310
311 if (root_level + 1 == level)
312 goto out;
313
314 path->lowest_level = level;
315 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
316 pr_debug("search slot in root %llu (level %d, ref count %d) returned "
317 "%d for key (%llu %u %llu)\n",
318 ref->root_id, level, ref->count, ret,
319 ref->key_for_search.objectid, ref->key_for_search.type,
320 ref->key_for_search.offset);
321 if (ret < 0)
322 goto out;
323
324 eb = path->nodes[level];
325 while (!eb) {
326 if (!level) {
327 WARN_ON(1);
328 ret = 1;
329 goto out;
330 }
331 level--;
332 eb = path->nodes[level];
333 }
334
335 ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
336 time_seq, ref->wanted_disk_byte,
337 extent_item_pos);
338 out:
339 path->lowest_level = 0;
340 btrfs_release_path(path);
341 return ret;
342 }
343
344 /*
345 * resolve all indirect backrefs from the list
346 */
347 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
348 struct btrfs_path *path, u64 time_seq,
349 struct list_head *head,
350 const u64 *extent_item_pos)
351 {
352 int err;
353 int ret = 0;
354 struct __prelim_ref *ref;
355 struct __prelim_ref *ref_safe;
356 struct __prelim_ref *new_ref;
357 struct ulist *parents;
358 struct ulist_node *node;
359 struct ulist_iterator uiter;
360
361 parents = ulist_alloc(GFP_NOFS);
362 if (!parents)
363 return -ENOMEM;
364
365 /*
366 * _safe allows us to insert directly after the current item without
367 * iterating over the newly inserted items.
368 * we're also allowed to re-assign ref during iteration.
369 */
370 list_for_each_entry_safe(ref, ref_safe, head, list) {
371 if (ref->parent) /* already direct */
372 continue;
373 if (ref->count == 0)
374 continue;
375 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
376 parents, extent_item_pos);
377 if (err == -ENOMEM)
378 goto out;
379 if (err)
380 continue;
381
382 /* we put the first parent into the ref at hand */
383 ULIST_ITER_INIT(&uiter);
384 node = ulist_next(parents, &uiter);
385 ref->parent = node ? node->val : 0;
386 ref->inode_list = node ?
387 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
388
389 /* additional parents require new refs being added here */
390 while ((node = ulist_next(parents, &uiter))) {
391 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
392 GFP_NOFS);
393 if (!new_ref) {
394 ret = -ENOMEM;
395 goto out;
396 }
397 memcpy(new_ref, ref, sizeof(*ref));
398 new_ref->parent = node->val;
399 new_ref->inode_list = (struct extent_inode_elem *)
400 (uintptr_t)node->aux;
401 list_add(&new_ref->list, &ref->list);
402 }
403 ulist_reinit(parents);
404 }
405 out:
406 ulist_free(parents);
407 return ret;
408 }
409
410 static inline int ref_for_same_block(struct __prelim_ref *ref1,
411 struct __prelim_ref *ref2)
412 {
413 if (ref1->level != ref2->level)
414 return 0;
415 if (ref1->root_id != ref2->root_id)
416 return 0;
417 if (ref1->key_for_search.type != ref2->key_for_search.type)
418 return 0;
419 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
420 return 0;
421 if (ref1->key_for_search.offset != ref2->key_for_search.offset)
422 return 0;
423 if (ref1->parent != ref2->parent)
424 return 0;
425
426 return 1;
427 }
428
429 /*
430 * read tree blocks and add keys where required.
431 */
432 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
433 struct list_head *head)
434 {
435 struct list_head *pos;
436 struct extent_buffer *eb;
437
438 list_for_each(pos, head) {
439 struct __prelim_ref *ref;
440 ref = list_entry(pos, struct __prelim_ref, list);
441
442 if (ref->parent)
443 continue;
444 if (ref->key_for_search.type)
445 continue;
446 BUG_ON(!ref->wanted_disk_byte);
447 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
448 fs_info->tree_root->leafsize, 0);
449 if (!eb || !extent_buffer_uptodate(eb)) {
450 free_extent_buffer(eb);
451 return -EIO;
452 }
453 btrfs_tree_read_lock(eb);
454 if (btrfs_header_level(eb) == 0)
455 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
456 else
457 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
458 btrfs_tree_read_unlock(eb);
459 free_extent_buffer(eb);
460 }
461 return 0;
462 }
463
464 /*
465 * merge two lists of backrefs and adjust counts accordingly
466 *
467 * mode = 1: merge identical keys, if key is set
468 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
469 * additionally, we could even add a key range for the blocks we
470 * looked into to merge even more (-> replace unresolved refs by those
471 * having a parent).
472 * mode = 2: merge identical parents
473 */
474 static void __merge_refs(struct list_head *head, int mode)
475 {
476 struct list_head *pos1;
477
478 list_for_each(pos1, head) {
479 struct list_head *n2;
480 struct list_head *pos2;
481 struct __prelim_ref *ref1;
482
483 ref1 = list_entry(pos1, struct __prelim_ref, list);
484
485 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
486 pos2 = n2, n2 = pos2->next) {
487 struct __prelim_ref *ref2;
488 struct __prelim_ref *xchg;
489 struct extent_inode_elem *eie;
490
491 ref2 = list_entry(pos2, struct __prelim_ref, list);
492
493 if (mode == 1) {
494 if (!ref_for_same_block(ref1, ref2))
495 continue;
496 if (!ref1->parent && ref2->parent) {
497 xchg = ref1;
498 ref1 = ref2;
499 ref2 = xchg;
500 }
501 } else {
502 if (ref1->parent != ref2->parent)
503 continue;
504 }
505
506 eie = ref1->inode_list;
507 while (eie && eie->next)
508 eie = eie->next;
509 if (eie)
510 eie->next = ref2->inode_list;
511 else
512 ref1->inode_list = ref2->inode_list;
513 ref1->count += ref2->count;
514
515 list_del(&ref2->list);
516 kmem_cache_free(btrfs_prelim_ref_cache, ref2);
517 }
518
519 }
520 }
521
522 /*
523 * add all currently queued delayed refs from this head whose seq nr is
524 * smaller or equal that seq to the list
525 */
526 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
527 struct list_head *prefs)
528 {
529 struct btrfs_delayed_extent_op *extent_op = head->extent_op;
530 struct rb_node *n = &head->node.rb_node;
531 struct btrfs_key key;
532 struct btrfs_key op_key = {0};
533 int sgn;
534 int ret = 0;
535
536 if (extent_op && extent_op->update_key)
537 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
538
539 while ((n = rb_prev(n))) {
540 struct btrfs_delayed_ref_node *node;
541 node = rb_entry(n, struct btrfs_delayed_ref_node,
542 rb_node);
543 if (node->bytenr != head->node.bytenr)
544 break;
545 WARN_ON(node->is_head);
546
547 if (node->seq > seq)
548 continue;
549
550 switch (node->action) {
551 case BTRFS_ADD_DELAYED_EXTENT:
552 case BTRFS_UPDATE_DELAYED_HEAD:
553 WARN_ON(1);
554 continue;
555 case BTRFS_ADD_DELAYED_REF:
556 sgn = 1;
557 break;
558 case BTRFS_DROP_DELAYED_REF:
559 sgn = -1;
560 break;
561 default:
562 BUG_ON(1);
563 }
564 switch (node->type) {
565 case BTRFS_TREE_BLOCK_REF_KEY: {
566 struct btrfs_delayed_tree_ref *ref;
567
568 ref = btrfs_delayed_node_to_tree_ref(node);
569 ret = __add_prelim_ref(prefs, ref->root, &op_key,
570 ref->level + 1, 0, node->bytenr,
571 node->ref_mod * sgn, GFP_ATOMIC);
572 break;
573 }
574 case BTRFS_SHARED_BLOCK_REF_KEY: {
575 struct btrfs_delayed_tree_ref *ref;
576
577 ref = btrfs_delayed_node_to_tree_ref(node);
578 ret = __add_prelim_ref(prefs, ref->root, NULL,
579 ref->level + 1, ref->parent,
580 node->bytenr,
581 node->ref_mod * sgn, GFP_ATOMIC);
582 break;
583 }
584 case BTRFS_EXTENT_DATA_REF_KEY: {
585 struct btrfs_delayed_data_ref *ref;
586 ref = btrfs_delayed_node_to_data_ref(node);
587
588 key.objectid = ref->objectid;
589 key.type = BTRFS_EXTENT_DATA_KEY;
590 key.offset = ref->offset;
591 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
592 node->bytenr,
593 node->ref_mod * sgn, GFP_ATOMIC);
594 break;
595 }
596 case BTRFS_SHARED_DATA_REF_KEY: {
597 struct btrfs_delayed_data_ref *ref;
598
599 ref = btrfs_delayed_node_to_data_ref(node);
600
601 key.objectid = ref->objectid;
602 key.type = BTRFS_EXTENT_DATA_KEY;
603 key.offset = ref->offset;
604 ret = __add_prelim_ref(prefs, ref->root, &key, 0,
605 ref->parent, node->bytenr,
606 node->ref_mod * sgn, GFP_ATOMIC);
607 break;
608 }
609 default:
610 WARN_ON(1);
611 }
612 if (ret)
613 return ret;
614 }
615
616 return 0;
617 }
618
619 /*
620 * add all inline backrefs for bytenr to the list
621 */
622 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
623 struct btrfs_path *path, u64 bytenr,
624 int *info_level, struct list_head *prefs)
625 {
626 int ret = 0;
627 int slot;
628 struct extent_buffer *leaf;
629 struct btrfs_key key;
630 struct btrfs_key found_key;
631 unsigned long ptr;
632 unsigned long end;
633 struct btrfs_extent_item *ei;
634 u64 flags;
635 u64 item_size;
636
637 /*
638 * enumerate all inline refs
639 */
640 leaf = path->nodes[0];
641 slot = path->slots[0];
642
643 item_size = btrfs_item_size_nr(leaf, slot);
644 BUG_ON(item_size < sizeof(*ei));
645
646 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
647 flags = btrfs_extent_flags(leaf, ei);
648 btrfs_item_key_to_cpu(leaf, &found_key, slot);
649
650 ptr = (unsigned long)(ei + 1);
651 end = (unsigned long)ei + item_size;
652
653 if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
654 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
655 struct btrfs_tree_block_info *info;
656
657 info = (struct btrfs_tree_block_info *)ptr;
658 *info_level = btrfs_tree_block_level(leaf, info);
659 ptr += sizeof(struct btrfs_tree_block_info);
660 BUG_ON(ptr > end);
661 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
662 *info_level = found_key.offset;
663 } else {
664 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
665 }
666
667 while (ptr < end) {
668 struct btrfs_extent_inline_ref *iref;
669 u64 offset;
670 int type;
671
672 iref = (struct btrfs_extent_inline_ref *)ptr;
673 type = btrfs_extent_inline_ref_type(leaf, iref);
674 offset = btrfs_extent_inline_ref_offset(leaf, iref);
675
676 switch (type) {
677 case BTRFS_SHARED_BLOCK_REF_KEY:
678 ret = __add_prelim_ref(prefs, 0, NULL,
679 *info_level + 1, offset,
680 bytenr, 1, GFP_NOFS);
681 break;
682 case BTRFS_SHARED_DATA_REF_KEY: {
683 struct btrfs_shared_data_ref *sdref;
684 int count;
685
686 sdref = (struct btrfs_shared_data_ref *)(iref + 1);
687 count = btrfs_shared_data_ref_count(leaf, sdref);
688 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
689 bytenr, count, GFP_NOFS);
690 break;
691 }
692 case BTRFS_TREE_BLOCK_REF_KEY:
693 ret = __add_prelim_ref(prefs, offset, NULL,
694 *info_level + 1, 0,
695 bytenr, 1, GFP_NOFS);
696 break;
697 case BTRFS_EXTENT_DATA_REF_KEY: {
698 struct btrfs_extent_data_ref *dref;
699 int count;
700 u64 root;
701
702 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
703 count = btrfs_extent_data_ref_count(leaf, dref);
704 key.objectid = btrfs_extent_data_ref_objectid(leaf,
705 dref);
706 key.type = BTRFS_EXTENT_DATA_KEY;
707 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
708 root = btrfs_extent_data_ref_root(leaf, dref);
709 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
710 bytenr, count, GFP_NOFS);
711 break;
712 }
713 default:
714 WARN_ON(1);
715 }
716 if (ret)
717 return ret;
718 ptr += btrfs_extent_inline_ref_size(type);
719 }
720
721 return 0;
722 }
723
724 /*
725 * add all non-inline backrefs for bytenr to the list
726 */
727 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
728 struct btrfs_path *path, u64 bytenr,
729 int info_level, struct list_head *prefs)
730 {
731 struct btrfs_root *extent_root = fs_info->extent_root;
732 int ret;
733 int slot;
734 struct extent_buffer *leaf;
735 struct btrfs_key key;
736
737 while (1) {
738 ret = btrfs_next_item(extent_root, path);
739 if (ret < 0)
740 break;
741 if (ret) {
742 ret = 0;
743 break;
744 }
745
746 slot = path->slots[0];
747 leaf = path->nodes[0];
748 btrfs_item_key_to_cpu(leaf, &key, slot);
749
750 if (key.objectid != bytenr)
751 break;
752 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
753 continue;
754 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
755 break;
756
757 switch (key.type) {
758 case BTRFS_SHARED_BLOCK_REF_KEY:
759 ret = __add_prelim_ref(prefs, 0, NULL,
760 info_level + 1, key.offset,
761 bytenr, 1, GFP_NOFS);
762 break;
763 case BTRFS_SHARED_DATA_REF_KEY: {
764 struct btrfs_shared_data_ref *sdref;
765 int count;
766
767 sdref = btrfs_item_ptr(leaf, slot,
768 struct btrfs_shared_data_ref);
769 count = btrfs_shared_data_ref_count(leaf, sdref);
770 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
771 bytenr, count, GFP_NOFS);
772 break;
773 }
774 case BTRFS_TREE_BLOCK_REF_KEY:
775 ret = __add_prelim_ref(prefs, key.offset, NULL,
776 info_level + 1, 0,
777 bytenr, 1, GFP_NOFS);
778 break;
779 case BTRFS_EXTENT_DATA_REF_KEY: {
780 struct btrfs_extent_data_ref *dref;
781 int count;
782 u64 root;
783
784 dref = btrfs_item_ptr(leaf, slot,
785 struct btrfs_extent_data_ref);
786 count = btrfs_extent_data_ref_count(leaf, dref);
787 key.objectid = btrfs_extent_data_ref_objectid(leaf,
788 dref);
789 key.type = BTRFS_EXTENT_DATA_KEY;
790 key.offset = btrfs_extent_data_ref_offset(leaf, dref);
791 root = btrfs_extent_data_ref_root(leaf, dref);
792 ret = __add_prelim_ref(prefs, root, &key, 0, 0,
793 bytenr, count, GFP_NOFS);
794 break;
795 }
796 default:
797 WARN_ON(1);
798 }
799 if (ret)
800 return ret;
801
802 }
803
804 return ret;
805 }
806
807 /*
808 * this adds all existing backrefs (inline backrefs, backrefs and delayed
809 * refs) for the given bytenr to the refs list, merges duplicates and resolves
810 * indirect refs to their parent bytenr.
811 * When roots are found, they're added to the roots list
812 *
813 * FIXME some caching might speed things up
814 */
815 static int find_parent_nodes(struct btrfs_trans_handle *trans,
816 struct btrfs_fs_info *fs_info, u64 bytenr,
817 u64 time_seq, struct ulist *refs,
818 struct ulist *roots, const u64 *extent_item_pos)
819 {
820 struct btrfs_key key;
821 struct btrfs_path *path;
822 struct btrfs_delayed_ref_root *delayed_refs = NULL;
823 struct btrfs_delayed_ref_head *head;
824 int info_level = 0;
825 int ret;
826 struct list_head prefs_delayed;
827 struct list_head prefs;
828 struct __prelim_ref *ref;
829
830 INIT_LIST_HEAD(&prefs);
831 INIT_LIST_HEAD(&prefs_delayed);
832
833 key.objectid = bytenr;
834 key.offset = (u64)-1;
835 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
836 key.type = BTRFS_METADATA_ITEM_KEY;
837 else
838 key.type = BTRFS_EXTENT_ITEM_KEY;
839
840 path = btrfs_alloc_path();
841 if (!path)
842 return -ENOMEM;
843 if (!trans)
844 path->search_commit_root = 1;
845
846 /*
847 * grab both a lock on the path and a lock on the delayed ref head.
848 * We need both to get a consistent picture of how the refs look
849 * at a specified point in time
850 */
851 again:
852 head = NULL;
853
854 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
855 if (ret < 0)
856 goto out;
857 BUG_ON(ret == 0);
858
859 if (trans) {
860 /*
861 * look if there are updates for this ref queued and lock the
862 * head
863 */
864 delayed_refs = &trans->transaction->delayed_refs;
865 spin_lock(&delayed_refs->lock);
866 head = btrfs_find_delayed_ref_head(trans, bytenr);
867 if (head) {
868 if (!mutex_trylock(&head->mutex)) {
869 atomic_inc(&head->node.refs);
870 spin_unlock(&delayed_refs->lock);
871
872 btrfs_release_path(path);
873
874 /*
875 * Mutex was contended, block until it's
876 * released and try again
877 */
878 mutex_lock(&head->mutex);
879 mutex_unlock(&head->mutex);
880 btrfs_put_delayed_ref(&head->node);
881 goto again;
882 }
883 ret = __add_delayed_refs(head, time_seq,
884 &prefs_delayed);
885 mutex_unlock(&head->mutex);
886 if (ret) {
887 spin_unlock(&delayed_refs->lock);
888 goto out;
889 }
890 }
891 spin_unlock(&delayed_refs->lock);
892 }
893
894 if (path->slots[0]) {
895 struct extent_buffer *leaf;
896 int slot;
897
898 path->slots[0]--;
899 leaf = path->nodes[0];
900 slot = path->slots[0];
901 btrfs_item_key_to_cpu(leaf, &key, slot);
902 if (key.objectid == bytenr &&
903 (key.type == BTRFS_EXTENT_ITEM_KEY ||
904 key.type == BTRFS_METADATA_ITEM_KEY)) {
905 ret = __add_inline_refs(fs_info, path, bytenr,
906 &info_level, &prefs);
907 if (ret)
908 goto out;
909 ret = __add_keyed_refs(fs_info, path, bytenr,
910 info_level, &prefs);
911 if (ret)
912 goto out;
913 }
914 }
915 btrfs_release_path(path);
916
917 list_splice_init(&prefs_delayed, &prefs);
918
919 ret = __add_missing_keys(fs_info, &prefs);
920 if (ret)
921 goto out;
922
923 __merge_refs(&prefs, 1);
924
925 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
926 extent_item_pos);
927 if (ret)
928 goto out;
929
930 __merge_refs(&prefs, 2);
931
932 while (!list_empty(&prefs)) {
933 ref = list_first_entry(&prefs, struct __prelim_ref, list);
934 WARN_ON(ref->count < 0);
935 if (ref->count && ref->root_id && ref->parent == 0) {
936 /* no parent == root of tree */
937 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
938 if (ret < 0)
939 goto out;
940 }
941 if (ref->count && ref->parent) {
942 struct extent_inode_elem *eie = NULL;
943 if (extent_item_pos && !ref->inode_list) {
944 u32 bsz;
945 struct extent_buffer *eb;
946 bsz = btrfs_level_size(fs_info->extent_root,
947 info_level);
948 eb = read_tree_block(fs_info->extent_root,
949 ref->parent, bsz, 0);
950 if (!eb || !extent_buffer_uptodate(eb)) {
951 free_extent_buffer(eb);
952 ret = -EIO;
953 goto out;
954 }
955 ret = find_extent_in_eb(eb, bytenr,
956 *extent_item_pos, &eie);
957 free_extent_buffer(eb);
958 if (ret < 0)
959 goto out;
960 ref->inode_list = eie;
961 }
962 ret = ulist_add_merge(refs, ref->parent,
963 (uintptr_t)ref->inode_list,
964 (u64 *)&eie, GFP_NOFS);
965 if (ret < 0)
966 goto out;
967 if (!ret && extent_item_pos) {
968 /*
969 * we've recorded that parent, so we must extend
970 * its inode list here
971 */
972 BUG_ON(!eie);
973 while (eie->next)
974 eie = eie->next;
975 eie->next = ref->inode_list;
976 }
977 }
978 list_del(&ref->list);
979 kmem_cache_free(btrfs_prelim_ref_cache, ref);
980 }
981
982 out:
983 btrfs_free_path(path);
984 while (!list_empty(&prefs)) {
985 ref = list_first_entry(&prefs, struct __prelim_ref, list);
986 list_del(&ref->list);
987 kmem_cache_free(btrfs_prelim_ref_cache, ref);
988 }
989 while (!list_empty(&prefs_delayed)) {
990 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
991 list);
992 list_del(&ref->list);
993 kmem_cache_free(btrfs_prelim_ref_cache, ref);
994 }
995
996 return ret;
997 }
998
999 static void free_leaf_list(struct ulist *blocks)
1000 {
1001 struct ulist_node *node = NULL;
1002 struct extent_inode_elem *eie;
1003 struct extent_inode_elem *eie_next;
1004 struct ulist_iterator uiter;
1005
1006 ULIST_ITER_INIT(&uiter);
1007 while ((node = ulist_next(blocks, &uiter))) {
1008 if (!node->aux)
1009 continue;
1010 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1011 for (; eie; eie = eie_next) {
1012 eie_next = eie->next;
1013 kfree(eie);
1014 }
1015 node->aux = 0;
1016 }
1017
1018 ulist_free(blocks);
1019 }
1020
1021 /*
1022 * Finds all leafs with a reference to the specified combination of bytenr and
1023 * offset. key_list_head will point to a list of corresponding keys (caller must
1024 * free each list element). The leafs will be stored in the leafs ulist, which
1025 * must be freed with ulist_free.
1026 *
1027 * returns 0 on success, <0 on error
1028 */
1029 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1030 struct btrfs_fs_info *fs_info, u64 bytenr,
1031 u64 time_seq, struct ulist **leafs,
1032 const u64 *extent_item_pos)
1033 {
1034 struct ulist *tmp;
1035 int ret;
1036
1037 tmp = ulist_alloc(GFP_NOFS);
1038 if (!tmp)
1039 return -ENOMEM;
1040 *leafs = ulist_alloc(GFP_NOFS);
1041 if (!*leafs) {
1042 ulist_free(tmp);
1043 return -ENOMEM;
1044 }
1045
1046 ret = find_parent_nodes(trans, fs_info, bytenr,
1047 time_seq, *leafs, tmp, extent_item_pos);
1048 ulist_free(tmp);
1049
1050 if (ret < 0 && ret != -ENOENT) {
1051 free_leaf_list(*leafs);
1052 return ret;
1053 }
1054
1055 return 0;
1056 }
1057
1058 /*
1059 * walk all backrefs for a given extent to find all roots that reference this
1060 * extent. Walking a backref means finding all extents that reference this
1061 * extent and in turn walk the backrefs of those, too. Naturally this is a
1062 * recursive process, but here it is implemented in an iterative fashion: We
1063 * find all referencing extents for the extent in question and put them on a
1064 * list. In turn, we find all referencing extents for those, further appending
1065 * to the list. The way we iterate the list allows adding more elements after
1066 * the current while iterating. The process stops when we reach the end of the
1067 * list. Found roots are added to the roots list.
1068 *
1069 * returns 0 on success, < 0 on error.
1070 */
1071 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1072 struct btrfs_fs_info *fs_info, u64 bytenr,
1073 u64 time_seq, struct ulist **roots)
1074 {
1075 struct ulist *tmp;
1076 struct ulist_node *node = NULL;
1077 struct ulist_iterator uiter;
1078 int ret;
1079
1080 tmp = ulist_alloc(GFP_NOFS);
1081 if (!tmp)
1082 return -ENOMEM;
1083 *roots = ulist_alloc(GFP_NOFS);
1084 if (!*roots) {
1085 ulist_free(tmp);
1086 return -ENOMEM;
1087 }
1088
1089 ULIST_ITER_INIT(&uiter);
1090 while (1) {
1091 ret = find_parent_nodes(trans, fs_info, bytenr,
1092 time_seq, tmp, *roots, NULL);
1093 if (ret < 0 && ret != -ENOENT) {
1094 ulist_free(tmp);
1095 ulist_free(*roots);
1096 return ret;
1097 }
1098 node = ulist_next(tmp, &uiter);
1099 if (!node)
1100 break;
1101 bytenr = node->val;
1102 }
1103
1104 ulist_free(tmp);
1105 return 0;
1106 }
1107
1108
1109 static int __inode_info(u64 inum, u64 ioff, u8 key_type,
1110 struct btrfs_root *fs_root, struct btrfs_path *path,
1111 struct btrfs_key *found_key)
1112 {
1113 int ret;
1114 struct btrfs_key key;
1115 struct extent_buffer *eb;
1116
1117 key.type = key_type;
1118 key.objectid = inum;
1119 key.offset = ioff;
1120
1121 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1122 if (ret < 0)
1123 return ret;
1124
1125 eb = path->nodes[0];
1126 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1127 ret = btrfs_next_leaf(fs_root, path);
1128 if (ret)
1129 return ret;
1130 eb = path->nodes[0];
1131 }
1132
1133 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1134 if (found_key->type != key.type || found_key->objectid != key.objectid)
1135 return 1;
1136
1137 return 0;
1138 }
1139
1140 /*
1141 * this makes the path point to (inum INODE_ITEM ioff)
1142 */
1143 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1144 struct btrfs_path *path)
1145 {
1146 struct btrfs_key key;
1147 return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
1148 &key);
1149 }
1150
1151 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1152 struct btrfs_path *path,
1153 struct btrfs_key *found_key)
1154 {
1155 return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
1156 found_key);
1157 }
1158
1159 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1160 u64 start_off, struct btrfs_path *path,
1161 struct btrfs_inode_extref **ret_extref,
1162 u64 *found_off)
1163 {
1164 int ret, slot;
1165 struct btrfs_key key;
1166 struct btrfs_key found_key;
1167 struct btrfs_inode_extref *extref;
1168 struct extent_buffer *leaf;
1169 unsigned long ptr;
1170
1171 key.objectid = inode_objectid;
1172 btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1173 key.offset = start_off;
1174
1175 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1176 if (ret < 0)
1177 return ret;
1178
1179 while (1) {
1180 leaf = path->nodes[0];
1181 slot = path->slots[0];
1182 if (slot >= btrfs_header_nritems(leaf)) {
1183 /*
1184 * If the item at offset is not found,
1185 * btrfs_search_slot will point us to the slot
1186 * where it should be inserted. In our case
1187 * that will be the slot directly before the
1188 * next INODE_REF_KEY_V2 item. In the case
1189 * that we're pointing to the last slot in a
1190 * leaf, we must move one leaf over.
1191 */
1192 ret = btrfs_next_leaf(root, path);
1193 if (ret) {
1194 if (ret >= 1)
1195 ret = -ENOENT;
1196 break;
1197 }
1198 continue;
1199 }
1200
1201 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1202
1203 /*
1204 * Check that we're still looking at an extended ref key for
1205 * this particular objectid. If we have different
1206 * objectid or type then there are no more to be found
1207 * in the tree and we can exit.
1208 */
1209 ret = -ENOENT;
1210 if (found_key.objectid != inode_objectid)
1211 break;
1212 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1213 break;
1214
1215 ret = 0;
1216 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1217 extref = (struct btrfs_inode_extref *)ptr;
1218 *ret_extref = extref;
1219 if (found_off)
1220 *found_off = found_key.offset;
1221 break;
1222 }
1223
1224 return ret;
1225 }
1226
1227 /*
1228 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1229 * Elements of the path are separated by '/' and the path is guaranteed to be
1230 * 0-terminated. the path is only given within the current file system.
1231 * Therefore, it never starts with a '/'. the caller is responsible to provide
1232 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1233 * the start point of the resulting string is returned. this pointer is within
1234 * dest, normally.
1235 * in case the path buffer would overflow, the pointer is decremented further
1236 * as if output was written to the buffer, though no more output is actually
1237 * generated. that way, the caller can determine how much space would be
1238 * required for the path to fit into the buffer. in that case, the returned
1239 * value will be smaller than dest. callers must check this!
1240 */
1241 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1242 u32 name_len, unsigned long name_off,
1243 struct extent_buffer *eb_in, u64 parent,
1244 char *dest, u32 size)
1245 {
1246 int slot;
1247 u64 next_inum;
1248 int ret;
1249 s64 bytes_left = ((s64)size) - 1;
1250 struct extent_buffer *eb = eb_in;
1251 struct btrfs_key found_key;
1252 int leave_spinning = path->leave_spinning;
1253 struct btrfs_inode_ref *iref;
1254
1255 if (bytes_left >= 0)
1256 dest[bytes_left] = '\0';
1257
1258 path->leave_spinning = 1;
1259 while (1) {
1260 bytes_left -= name_len;
1261 if (bytes_left >= 0)
1262 read_extent_buffer(eb, dest + bytes_left,
1263 name_off, name_len);
1264 if (eb != eb_in) {
1265 btrfs_tree_read_unlock_blocking(eb);
1266 free_extent_buffer(eb);
1267 }
1268 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1269 if (ret > 0)
1270 ret = -ENOENT;
1271 if (ret)
1272 break;
1273
1274 next_inum = found_key.offset;
1275
1276 /* regular exit ahead */
1277 if (parent == next_inum)
1278 break;
1279
1280 slot = path->slots[0];
1281 eb = path->nodes[0];
1282 /* make sure we can use eb after releasing the path */
1283 if (eb != eb_in) {
1284 atomic_inc(&eb->refs);
1285 btrfs_tree_read_lock(eb);
1286 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1287 }
1288 btrfs_release_path(path);
1289 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1290
1291 name_len = btrfs_inode_ref_name_len(eb, iref);
1292 name_off = (unsigned long)(iref + 1);
1293
1294 parent = next_inum;
1295 --bytes_left;
1296 if (bytes_left >= 0)
1297 dest[bytes_left] = '/';
1298 }
1299
1300 btrfs_release_path(path);
1301 path->leave_spinning = leave_spinning;
1302
1303 if (ret)
1304 return ERR_PTR(ret);
1305
1306 return dest + bytes_left;
1307 }
1308
1309 /*
1310 * this makes the path point to (logical EXTENT_ITEM *)
1311 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1312 * tree blocks and <0 on error.
1313 */
1314 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1315 struct btrfs_path *path, struct btrfs_key *found_key,
1316 u64 *flags_ret)
1317 {
1318 int ret;
1319 u64 flags;
1320 u64 size = 0;
1321 u32 item_size;
1322 struct extent_buffer *eb;
1323 struct btrfs_extent_item *ei;
1324 struct btrfs_key key;
1325
1326 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1327 key.type = BTRFS_METADATA_ITEM_KEY;
1328 else
1329 key.type = BTRFS_EXTENT_ITEM_KEY;
1330 key.objectid = logical;
1331 key.offset = (u64)-1;
1332
1333 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1334 if (ret < 0)
1335 return ret;
1336 ret = btrfs_previous_item(fs_info->extent_root, path,
1337 0, BTRFS_EXTENT_ITEM_KEY);
1338 if (ret < 0)
1339 return ret;
1340
1341 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1342 if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1343 size = fs_info->extent_root->leafsize;
1344 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1345 size = found_key->offset;
1346
1347 if ((found_key->type != BTRFS_EXTENT_ITEM_KEY &&
1348 found_key->type != BTRFS_METADATA_ITEM_KEY) ||
1349 found_key->objectid > logical ||
1350 found_key->objectid + size <= logical) {
1351 pr_debug("logical %llu is not within any extent\n", logical);
1352 return -ENOENT;
1353 }
1354
1355 eb = path->nodes[0];
1356 item_size = btrfs_item_size_nr(eb, path->slots[0]);
1357 BUG_ON(item_size < sizeof(*ei));
1358
1359 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1360 flags = btrfs_extent_flags(eb, ei);
1361
1362 pr_debug("logical %llu is at position %llu within the extent (%llu "
1363 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1364 logical, logical - found_key->objectid, found_key->objectid,
1365 found_key->offset, flags, item_size);
1366
1367 WARN_ON(!flags_ret);
1368 if (flags_ret) {
1369 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1370 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1371 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1372 *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1373 else
1374 BUG_ON(1);
1375 return 0;
1376 }
1377
1378 return -EIO;
1379 }
1380
1381 /*
1382 * helper function to iterate extent inline refs. ptr must point to a 0 value
1383 * for the first call and may be modified. it is used to track state.
1384 * if more refs exist, 0 is returned and the next call to
1385 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1386 * next ref. after the last ref was processed, 1 is returned.
1387 * returns <0 on error
1388 */
1389 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1390 struct btrfs_extent_item *ei, u32 item_size,
1391 struct btrfs_extent_inline_ref **out_eiref,
1392 int *out_type)
1393 {
1394 unsigned long end;
1395 u64 flags;
1396 struct btrfs_tree_block_info *info;
1397
1398 if (!*ptr) {
1399 /* first call */
1400 flags = btrfs_extent_flags(eb, ei);
1401 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1402 info = (struct btrfs_tree_block_info *)(ei + 1);
1403 *out_eiref =
1404 (struct btrfs_extent_inline_ref *)(info + 1);
1405 } else {
1406 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1407 }
1408 *ptr = (unsigned long)*out_eiref;
1409 if ((void *)*ptr >= (void *)ei + item_size)
1410 return -ENOENT;
1411 }
1412
1413 end = (unsigned long)ei + item_size;
1414 *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1415 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1416
1417 *ptr += btrfs_extent_inline_ref_size(*out_type);
1418 WARN_ON(*ptr > end);
1419 if (*ptr == end)
1420 return 1; /* last */
1421
1422 return 0;
1423 }
1424
1425 /*
1426 * reads the tree block backref for an extent. tree level and root are returned
1427 * through out_level and out_root. ptr must point to a 0 value for the first
1428 * call and may be modified (see __get_extent_inline_ref comment).
1429 * returns 0 if data was provided, 1 if there was no more data to provide or
1430 * <0 on error.
1431 */
1432 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1433 struct btrfs_extent_item *ei, u32 item_size,
1434 u64 *out_root, u8 *out_level)
1435 {
1436 int ret;
1437 int type;
1438 struct btrfs_tree_block_info *info;
1439 struct btrfs_extent_inline_ref *eiref;
1440
1441 if (*ptr == (unsigned long)-1)
1442 return 1;
1443
1444 while (1) {
1445 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1446 &eiref, &type);
1447 if (ret < 0)
1448 return ret;
1449
1450 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1451 type == BTRFS_SHARED_BLOCK_REF_KEY)
1452 break;
1453
1454 if (ret == 1)
1455 return 1;
1456 }
1457
1458 /* we can treat both ref types equally here */
1459 info = (struct btrfs_tree_block_info *)(ei + 1);
1460 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1461 *out_level = btrfs_tree_block_level(eb, info);
1462
1463 if (ret == 1)
1464 *ptr = (unsigned long)-1;
1465
1466 return 0;
1467 }
1468
1469 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1470 u64 root, u64 extent_item_objectid,
1471 iterate_extent_inodes_t *iterate, void *ctx)
1472 {
1473 struct extent_inode_elem *eie;
1474 int ret = 0;
1475
1476 for (eie = inode_list; eie; eie = eie->next) {
1477 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1478 "root %llu\n", extent_item_objectid,
1479 eie->inum, eie->offset, root);
1480 ret = iterate(eie->inum, eie->offset, root, ctx);
1481 if (ret) {
1482 pr_debug("stopping iteration for %llu due to ret=%d\n",
1483 extent_item_objectid, ret);
1484 break;
1485 }
1486 }
1487
1488 return ret;
1489 }
1490
1491 /*
1492 * calls iterate() for every inode that references the extent identified by
1493 * the given parameters.
1494 * when the iterator function returns a non-zero value, iteration stops.
1495 */
1496 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1497 u64 extent_item_objectid, u64 extent_item_pos,
1498 int search_commit_root,
1499 iterate_extent_inodes_t *iterate, void *ctx)
1500 {
1501 int ret;
1502 struct btrfs_trans_handle *trans = NULL;
1503 struct ulist *refs = NULL;
1504 struct ulist *roots = NULL;
1505 struct ulist_node *ref_node = NULL;
1506 struct ulist_node *root_node = NULL;
1507 struct seq_list tree_mod_seq_elem = {};
1508 struct ulist_iterator ref_uiter;
1509 struct ulist_iterator root_uiter;
1510
1511 pr_debug("resolving all inodes for extent %llu\n",
1512 extent_item_objectid);
1513
1514 if (!search_commit_root) {
1515 trans = btrfs_join_transaction(fs_info->extent_root);
1516 if (IS_ERR(trans))
1517 return PTR_ERR(trans);
1518 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1519 }
1520
1521 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1522 tree_mod_seq_elem.seq, &refs,
1523 &extent_item_pos);
1524 if (ret)
1525 goto out;
1526
1527 ULIST_ITER_INIT(&ref_uiter);
1528 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1529 ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
1530 tree_mod_seq_elem.seq, &roots);
1531 if (ret)
1532 break;
1533 ULIST_ITER_INIT(&root_uiter);
1534 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1535 pr_debug("root %llu references leaf %llu, data list "
1536 "%#llx\n", root_node->val, ref_node->val,
1537 ref_node->aux);
1538 ret = iterate_leaf_refs((struct extent_inode_elem *)
1539 (uintptr_t)ref_node->aux,
1540 root_node->val,
1541 extent_item_objectid,
1542 iterate, ctx);
1543 }
1544 ulist_free(roots);
1545 }
1546
1547 free_leaf_list(refs);
1548 out:
1549 if (!search_commit_root) {
1550 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1551 btrfs_end_transaction(trans, fs_info->extent_root);
1552 }
1553
1554 return ret;
1555 }
1556
1557 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1558 struct btrfs_path *path,
1559 iterate_extent_inodes_t *iterate, void *ctx)
1560 {
1561 int ret;
1562 u64 extent_item_pos;
1563 u64 flags = 0;
1564 struct btrfs_key found_key;
1565 int search_commit_root = path->search_commit_root;
1566
1567 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1568 btrfs_release_path(path);
1569 if (ret < 0)
1570 return ret;
1571 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1572 return -EINVAL;
1573
1574 extent_item_pos = logical - found_key.objectid;
1575 ret = iterate_extent_inodes(fs_info, found_key.objectid,
1576 extent_item_pos, search_commit_root,
1577 iterate, ctx);
1578
1579 return ret;
1580 }
1581
1582 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1583 struct extent_buffer *eb, void *ctx);
1584
1585 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1586 struct btrfs_path *path,
1587 iterate_irefs_t *iterate, void *ctx)
1588 {
1589 int ret = 0;
1590 int slot;
1591 u32 cur;
1592 u32 len;
1593 u32 name_len;
1594 u64 parent = 0;
1595 int found = 0;
1596 struct extent_buffer *eb;
1597 struct btrfs_item *item;
1598 struct btrfs_inode_ref *iref;
1599 struct btrfs_key found_key;
1600
1601 while (!ret) {
1602 path->leave_spinning = 1;
1603 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1604 &found_key);
1605 if (ret < 0)
1606 break;
1607 if (ret) {
1608 ret = found ? 0 : -ENOENT;
1609 break;
1610 }
1611 ++found;
1612
1613 parent = found_key.offset;
1614 slot = path->slots[0];
1615 eb = path->nodes[0];
1616 /* make sure we can use eb after releasing the path */
1617 atomic_inc(&eb->refs);
1618 btrfs_tree_read_lock(eb);
1619 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1620 btrfs_release_path(path);
1621
1622 item = btrfs_item_nr(eb, slot);
1623 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1624
1625 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1626 name_len = btrfs_inode_ref_name_len(eb, iref);
1627 /* path must be released before calling iterate()! */
1628 pr_debug("following ref at offset %u for inode %llu in "
1629 "tree %llu\n", cur, found_key.objectid,
1630 fs_root->objectid);
1631 ret = iterate(parent, name_len,
1632 (unsigned long)(iref + 1), eb, ctx);
1633 if (ret)
1634 break;
1635 len = sizeof(*iref) + name_len;
1636 iref = (struct btrfs_inode_ref *)((char *)iref + len);
1637 }
1638 btrfs_tree_read_unlock_blocking(eb);
1639 free_extent_buffer(eb);
1640 }
1641
1642 btrfs_release_path(path);
1643
1644 return ret;
1645 }
1646
1647 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1648 struct btrfs_path *path,
1649 iterate_irefs_t *iterate, void *ctx)
1650 {
1651 int ret;
1652 int slot;
1653 u64 offset = 0;
1654 u64 parent;
1655 int found = 0;
1656 struct extent_buffer *eb;
1657 struct btrfs_inode_extref *extref;
1658 struct extent_buffer *leaf;
1659 u32 item_size;
1660 u32 cur_offset;
1661 unsigned long ptr;
1662
1663 while (1) {
1664 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1665 &offset);
1666 if (ret < 0)
1667 break;
1668 if (ret) {
1669 ret = found ? 0 : -ENOENT;
1670 break;
1671 }
1672 ++found;
1673
1674 slot = path->slots[0];
1675 eb = path->nodes[0];
1676 /* make sure we can use eb after releasing the path */
1677 atomic_inc(&eb->refs);
1678
1679 btrfs_tree_read_lock(eb);
1680 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1681 btrfs_release_path(path);
1682
1683 leaf = path->nodes[0];
1684 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1685 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1686 cur_offset = 0;
1687
1688 while (cur_offset < item_size) {
1689 u32 name_len;
1690
1691 extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1692 parent = btrfs_inode_extref_parent(eb, extref);
1693 name_len = btrfs_inode_extref_name_len(eb, extref);
1694 ret = iterate(parent, name_len,
1695 (unsigned long)&extref->name, eb, ctx);
1696 if (ret)
1697 break;
1698
1699 cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1700 cur_offset += sizeof(*extref);
1701 }
1702 btrfs_tree_read_unlock_blocking(eb);
1703 free_extent_buffer(eb);
1704
1705 offset++;
1706 }
1707
1708 btrfs_release_path(path);
1709
1710 return ret;
1711 }
1712
1713 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1714 struct btrfs_path *path, iterate_irefs_t *iterate,
1715 void *ctx)
1716 {
1717 int ret;
1718 int found_refs = 0;
1719
1720 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1721 if (!ret)
1722 ++found_refs;
1723 else if (ret != -ENOENT)
1724 return ret;
1725
1726 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1727 if (ret == -ENOENT && found_refs)
1728 return 0;
1729
1730 return ret;
1731 }
1732
1733 /*
1734 * returns 0 if the path could be dumped (probably truncated)
1735 * returns <0 in case of an error
1736 */
1737 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1738 struct extent_buffer *eb, void *ctx)
1739 {
1740 struct inode_fs_paths *ipath = ctx;
1741 char *fspath;
1742 char *fspath_min;
1743 int i = ipath->fspath->elem_cnt;
1744 const int s_ptr = sizeof(char *);
1745 u32 bytes_left;
1746
1747 bytes_left = ipath->fspath->bytes_left > s_ptr ?
1748 ipath->fspath->bytes_left - s_ptr : 0;
1749
1750 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1751 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1752 name_off, eb, inum, fspath_min, bytes_left);
1753 if (IS_ERR(fspath))
1754 return PTR_ERR(fspath);
1755
1756 if (fspath > fspath_min) {
1757 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1758 ++ipath->fspath->elem_cnt;
1759 ipath->fspath->bytes_left = fspath - fspath_min;
1760 } else {
1761 ++ipath->fspath->elem_missed;
1762 ipath->fspath->bytes_missing += fspath_min - fspath;
1763 ipath->fspath->bytes_left = 0;
1764 }
1765
1766 return 0;
1767 }
1768
1769 /*
1770 * this dumps all file system paths to the inode into the ipath struct, provided
1771 * is has been created large enough. each path is zero-terminated and accessed
1772 * from ipath->fspath->val[i].
1773 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1774 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1775 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1776 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1777 * have been needed to return all paths.
1778 */
1779 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1780 {
1781 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1782 inode_to_path, ipath);
1783 }
1784
1785 struct btrfs_data_container *init_data_container(u32 total_bytes)
1786 {
1787 struct btrfs_data_container *data;
1788 size_t alloc_bytes;
1789
1790 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1791 data = vmalloc(alloc_bytes);
1792 if (!data)
1793 return ERR_PTR(-ENOMEM);
1794
1795 if (total_bytes >= sizeof(*data)) {
1796 data->bytes_left = total_bytes - sizeof(*data);
1797 data->bytes_missing = 0;
1798 } else {
1799 data->bytes_missing = sizeof(*data) - total_bytes;
1800 data->bytes_left = 0;
1801 }
1802
1803 data->elem_cnt = 0;
1804 data->elem_missed = 0;
1805
1806 return data;
1807 }
1808
1809 /*
1810 * allocates space to return multiple file system paths for an inode.
1811 * total_bytes to allocate are passed, note that space usable for actual path
1812 * information will be total_bytes - sizeof(struct inode_fs_paths).
1813 * the returned pointer must be freed with free_ipath() in the end.
1814 */
1815 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1816 struct btrfs_path *path)
1817 {
1818 struct inode_fs_paths *ifp;
1819 struct btrfs_data_container *fspath;
1820
1821 fspath = init_data_container(total_bytes);
1822 if (IS_ERR(fspath))
1823 return (void *)fspath;
1824
1825 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1826 if (!ifp) {
1827 kfree(fspath);
1828 return ERR_PTR(-ENOMEM);
1829 }
1830
1831 ifp->btrfs_path = path;
1832 ifp->fspath = fspath;
1833 ifp->fs_root = fs_root;
1834
1835 return ifp;
1836 }
1837
1838 void free_ipath(struct inode_fs_paths *ipath)
1839 {
1840 if (!ipath)
1841 return;
1842 vfree(ipath->fspath);
1843 kfree(ipath);
1844 }
Linux kernel - Deliverables
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