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-rw-r--r--fs/btrfs/backref.c776
1 files changed, 776 insertions, 0 deletions
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
new file mode 100644
index 000000000000..22c64fff1bd5
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+++ b/fs/btrfs/backref.c
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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 "ctree.h"
20#include "disk-io.h"
21#include "backref.h"
22
23struct __data_ref {
24 struct list_head list;
25 u64 inum;
26 u64 root;
27 u64 extent_data_item_offset;
28};
29
30struct __shared_ref {
31 struct list_head list;
32 u64 disk_byte;
33};
34
35static int __inode_info(u64 inum, u64 ioff, u8 key_type,
36 struct btrfs_root *fs_root, struct btrfs_path *path,
37 struct btrfs_key *found_key)
38{
39 int ret;
40 struct btrfs_key key;
41 struct extent_buffer *eb;
42
43 key.type = key_type;
44 key.objectid = inum;
45 key.offset = ioff;
46
47 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
48 if (ret < 0)
49 return ret;
50
51 eb = path->nodes[0];
52 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
53 ret = btrfs_next_leaf(fs_root, path);
54 if (ret)
55 return ret;
56 eb = path->nodes[0];
57 }
58
59 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
60 if (found_key->type != key.type || found_key->objectid != key.objectid)
61 return 1;
62
63 return 0;
64}
65
66/*
67 * this makes the path point to (inum INODE_ITEM ioff)
68 */
69int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
70 struct btrfs_path *path)
71{
72 struct btrfs_key key;
73 return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
74 &key);
75}
76
77static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
78 struct btrfs_path *path,
79 struct btrfs_key *found_key)
80{
81 return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
82 found_key);
83}
84
85/*
86 * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
87 * of the path are separated by '/' and the path is guaranteed to be
88 * 0-terminated. the path is only given within the current file system.
89 * Therefore, it never starts with a '/'. the caller is responsible to provide
90 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
91 * the start point of the resulting string is returned. this pointer is within
92 * dest, normally.
93 * in case the path buffer would overflow, the pointer is decremented further
94 * as if output was written to the buffer, though no more output is actually
95 * generated. that way, the caller can determine how much space would be
96 * required for the path to fit into the buffer. in that case, the returned
97 * value will be smaller than dest. callers must check this!
98 */
99static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
100 struct btrfs_inode_ref *iref,
101 struct extent_buffer *eb_in, u64 parent,
102 char *dest, u32 size)
103{
104 u32 len;
105 int slot;
106 u64 next_inum;
107 int ret;
108 s64 bytes_left = size - 1;
109 struct extent_buffer *eb = eb_in;
110 struct btrfs_key found_key;
111
112 if (bytes_left >= 0)
113 dest[bytes_left] = '\0';
114
115 while (1) {
116 len = btrfs_inode_ref_name_len(eb, iref);
117 bytes_left -= len;
118 if (bytes_left >= 0)
119 read_extent_buffer(eb, dest + bytes_left,
120 (unsigned long)(iref + 1), len);
121 if (eb != eb_in)
122 free_extent_buffer(eb);
123 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
124 if (ret)
125 break;
126 next_inum = found_key.offset;
127
128 /* regular exit ahead */
129 if (parent == next_inum)
130 break;
131
132 slot = path->slots[0];
133 eb = path->nodes[0];
134 /* make sure we can use eb after releasing the path */
135 if (eb != eb_in)
136 atomic_inc(&eb->refs);
137 btrfs_release_path(path);
138
139 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
140 parent = next_inum;
141 --bytes_left;
142 if (bytes_left >= 0)
143 dest[bytes_left] = '/';
144 }
145
146 btrfs_release_path(path);
147
148 if (ret)
149 return ERR_PTR(ret);
150
151 return dest + bytes_left;
152}
153
154/*
155 * this makes the path point to (logical EXTENT_ITEM *)
156 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
157 * tree blocks and <0 on error.
158 */
159int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
160 struct btrfs_path *path, struct btrfs_key *found_key)
161{
162 int ret;
163 u64 flags;
164 u32 item_size;
165 struct extent_buffer *eb;
166 struct btrfs_extent_item *ei;
167 struct btrfs_key key;
168
169 key.type = BTRFS_EXTENT_ITEM_KEY;
170 key.objectid = logical;
171 key.offset = (u64)-1;
172
173 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
174 if (ret < 0)
175 return ret;
176 ret = btrfs_previous_item(fs_info->extent_root, path,
177 0, BTRFS_EXTENT_ITEM_KEY);
178 if (ret < 0)
179 return ret;
180
181 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
182 if (found_key->type != BTRFS_EXTENT_ITEM_KEY ||
183 found_key->objectid > logical ||
184 found_key->objectid + found_key->offset <= logical)
185 return -ENOENT;
186
187 eb = path->nodes[0];
188 item_size = btrfs_item_size_nr(eb, path->slots[0]);
189 BUG_ON(item_size < sizeof(*ei));
190
191 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
192 flags = btrfs_extent_flags(eb, ei);
193
194 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
195 return BTRFS_EXTENT_FLAG_TREE_BLOCK;
196 if (flags & BTRFS_EXTENT_FLAG_DATA)
197 return BTRFS_EXTENT_FLAG_DATA;
198
199 return -EIO;
200}
201
202/*
203 * helper function to iterate extent inline refs. ptr must point to a 0 value
204 * for the first call and may be modified. it is used to track state.
205 * if more refs exist, 0 is returned and the next call to
206 * __get_extent_inline_ref must pass the modified ptr parameter to get the
207 * next ref. after the last ref was processed, 1 is returned.
208 * returns <0 on error
209 */
210static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
211 struct btrfs_extent_item *ei, u32 item_size,
212 struct btrfs_extent_inline_ref **out_eiref,
213 int *out_type)
214{
215 unsigned long end;
216 u64 flags;
217 struct btrfs_tree_block_info *info;
218
219 if (!*ptr) {
220 /* first call */
221 flags = btrfs_extent_flags(eb, ei);
222 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
223 info = (struct btrfs_tree_block_info *)(ei + 1);
224 *out_eiref =
225 (struct btrfs_extent_inline_ref *)(info + 1);
226 } else {
227 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
228 }
229 *ptr = (unsigned long)*out_eiref;
230 if ((void *)*ptr >= (void *)ei + item_size)
231 return -ENOENT;
232 }
233
234 end = (unsigned long)ei + item_size;
235 *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
236 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
237
238 *ptr += btrfs_extent_inline_ref_size(*out_type);
239 WARN_ON(*ptr > end);
240 if (*ptr == end)
241 return 1; /* last */
242
243 return 0;
244}
245
246/*
247 * reads the tree block backref for an extent. tree level and root are returned
248 * through out_level and out_root. ptr must point to a 0 value for the first
249 * call and may be modified (see __get_extent_inline_ref comment).
250 * returns 0 if data was provided, 1 if there was no more data to provide or
251 * <0 on error.
252 */
253int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
254 struct btrfs_extent_item *ei, u32 item_size,
255 u64 *out_root, u8 *out_level)
256{
257 int ret;
258 int type;
259 struct btrfs_tree_block_info *info;
260 struct btrfs_extent_inline_ref *eiref;
261
262 if (*ptr == (unsigned long)-1)
263 return 1;
264
265 while (1) {
266 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
267 &eiref, &type);
268 if (ret < 0)
269 return ret;
270
271 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
272 type == BTRFS_SHARED_BLOCK_REF_KEY)
273 break;
274
275 if (ret == 1)
276 return 1;
277 }
278
279 /* we can treat both ref types equally here */
280 info = (struct btrfs_tree_block_info *)(ei + 1);
281 *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
282 *out_level = btrfs_tree_block_level(eb, info);
283
284 if (ret == 1)
285 *ptr = (unsigned long)-1;
286
287 return 0;
288}
289
290static int __data_list_add(struct list_head *head, u64 inum,
291 u64 extent_data_item_offset, u64 root)
292{
293 struct __data_ref *ref;
294
295 ref = kmalloc(sizeof(*ref), GFP_NOFS);
296 if (!ref)
297 return -ENOMEM;
298
299 ref->inum = inum;
300 ref->extent_data_item_offset = extent_data_item_offset;
301 ref->root = root;
302 list_add_tail(&ref->list, head);
303
304 return 0;
305}
306
307static int __data_list_add_eb(struct list_head *head, struct extent_buffer *eb,
308 struct btrfs_extent_data_ref *dref)
309{
310 return __data_list_add(head, btrfs_extent_data_ref_objectid(eb, dref),
311 btrfs_extent_data_ref_offset(eb, dref),
312 btrfs_extent_data_ref_root(eb, dref));
313}
314
315static int __shared_list_add(struct list_head *head, u64 disk_byte)
316{
317 struct __shared_ref *ref;
318
319 ref = kmalloc(sizeof(*ref), GFP_NOFS);
320 if (!ref)
321 return -ENOMEM;
322
323 ref->disk_byte = disk_byte;
324 list_add_tail(&ref->list, head);
325
326 return 0;
327}
328
329static int __iter_shared_inline_ref_inodes(struct btrfs_fs_info *fs_info,
330 u64 logical, u64 inum,
331 u64 extent_data_item_offset,
332 u64 extent_offset,
333 struct btrfs_path *path,
334 struct list_head *data_refs,
335 iterate_extent_inodes_t *iterate,
336 void *ctx)
337{
338 u64 ref_root;
339 u32 item_size;
340 struct btrfs_key key;
341 struct extent_buffer *eb;
342 struct btrfs_extent_item *ei;
343 struct btrfs_extent_inline_ref *eiref;
344 struct __data_ref *ref;
345 int ret;
346 int type;
347 int last;
348 unsigned long ptr = 0;
349
350 WARN_ON(!list_empty(data_refs));
351 ret = extent_from_logical(fs_info, logical, path, &key);
352 if (ret & BTRFS_EXTENT_FLAG_DATA)
353 ret = -EIO;
354 if (ret < 0)
355 goto out;
356
357 eb = path->nodes[0];
358 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
359 item_size = btrfs_item_size_nr(eb, path->slots[0]);
360
361 ret = 0;
362 ref_root = 0;
363 /*
364 * as done in iterate_extent_inodes, we first build a list of refs to
365 * iterate, then free the path and then iterate them to avoid deadlocks.
366 */
367 do {
368 last = __get_extent_inline_ref(&ptr, eb, ei, item_size,
369 &eiref, &type);
370 if (last < 0) {
371 ret = last;
372 goto out;
373 }
374 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
375 type == BTRFS_SHARED_BLOCK_REF_KEY) {
376 ref_root = btrfs_extent_inline_ref_offset(eb, eiref);
377 ret = __data_list_add(data_refs, inum,
378 extent_data_item_offset,
379 ref_root);
380 }
381 } while (!ret && !last);
382
383 btrfs_release_path(path);
384
385 if (ref_root == 0) {
386 printk(KERN_ERR "btrfs: failed to find tree block ref "
387 "for shared data backref %llu\n", logical);
388 WARN_ON(1);
389 ret = -EIO;
390 }
391
392out:
393 while (!list_empty(data_refs)) {
394 ref = list_first_entry(data_refs, struct __data_ref, list);
395 list_del(&ref->list);
396 if (!ret)
397 ret = iterate(ref->inum, extent_offset +
398 ref->extent_data_item_offset,
399 ref->root, ctx);
400 kfree(ref);
401 }
402
403 return ret;
404}
405
406static int __iter_shared_inline_ref(struct btrfs_fs_info *fs_info,
407 u64 logical, u64 orig_extent_item_objectid,
408 u64 extent_offset, struct btrfs_path *path,
409 struct list_head *data_refs,
410 iterate_extent_inodes_t *iterate,
411 void *ctx)
412{
413 u64 disk_byte;
414 struct btrfs_key key;
415 struct btrfs_file_extent_item *fi;
416 struct extent_buffer *eb;
417 int slot;
418 int nritems;
419 int ret;
420 int found = 0;
421
422 eb = read_tree_block(fs_info->tree_root, logical,
423 fs_info->tree_root->leafsize, 0);
424 if (!eb)
425 return -EIO;
426
427 /*
428 * from the shared data ref, we only have the leaf but we need
429 * the key. thus, we must look into all items and see that we
430 * find one (some) with a reference to our extent item.
431 */
432 nritems = btrfs_header_nritems(eb);
433 for (slot = 0; slot < nritems; ++slot) {
434 btrfs_item_key_to_cpu(eb, &key, slot);
435 if (key.type != BTRFS_EXTENT_DATA_KEY)
436 continue;
437 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
438 if (!fi) {
439 free_extent_buffer(eb);
440 return -EIO;
441 }
442 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
443 if (disk_byte != orig_extent_item_objectid) {
444 if (found)
445 break;
446 else
447 continue;
448 }
449 ++found;
450 ret = __iter_shared_inline_ref_inodes(fs_info, logical,
451 key.objectid,
452 key.offset,
453 extent_offset, path,
454 data_refs,
455 iterate, ctx);
456 if (ret)
457 break;
458 }
459
460 if (!found) {
461 printk(KERN_ERR "btrfs: failed to follow shared data backref "
462 "to parent %llu\n", logical);
463 WARN_ON(1);
464 ret = -EIO;
465 }
466
467 free_extent_buffer(eb);
468 return ret;
469}
470
471/*
472 * calls iterate() for every inode that references the extent identified by
473 * the given parameters. will use the path given as a parameter and return it
474 * released.
475 * when the iterator function returns a non-zero value, iteration stops.
476 */
477int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
478 struct btrfs_path *path,
479 u64 extent_item_objectid,
480 u64 extent_offset,
481 iterate_extent_inodes_t *iterate, void *ctx)
482{
483 unsigned long ptr = 0;
484 int last;
485 int ret;
486 int type;
487 u64 logical;
488 u32 item_size;
489 struct btrfs_extent_inline_ref *eiref;
490 struct btrfs_extent_data_ref *dref;
491 struct extent_buffer *eb;
492 struct btrfs_extent_item *ei;
493 struct btrfs_key key;
494 struct list_head data_refs = LIST_HEAD_INIT(data_refs);
495 struct list_head shared_refs = LIST_HEAD_INIT(shared_refs);
496 struct __data_ref *ref_d;
497 struct __shared_ref *ref_s;
498
499 eb = path->nodes[0];
500 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
501 item_size = btrfs_item_size_nr(eb, path->slots[0]);
502
503 /* first we iterate the inline refs, ... */
504 do {
505 last = __get_extent_inline_ref(&ptr, eb, ei, item_size,
506 &eiref, &type);
507 if (last == -ENOENT) {
508 ret = 0;
509 break;
510 }
511 if (last < 0) {
512 ret = last;
513 break;
514 }
515
516 if (type == BTRFS_EXTENT_DATA_REF_KEY) {
517 dref = (struct btrfs_extent_data_ref *)(&eiref->offset);
518 ret = __data_list_add_eb(&data_refs, eb, dref);
519 } else if (type == BTRFS_SHARED_DATA_REF_KEY) {
520 logical = btrfs_extent_inline_ref_offset(eb, eiref);
521 ret = __shared_list_add(&shared_refs, logical);
522 }
523 } while (!ret && !last);
524
525 /* ... then we proceed to in-tree references and ... */
526 while (!ret) {
527 ++path->slots[0];
528 if (path->slots[0] > btrfs_header_nritems(eb)) {
529 ret = btrfs_next_leaf(fs_info->extent_root, path);
530 if (ret) {
531 if (ret == 1)
532 ret = 0; /* we're done */
533 break;
534 }
535 eb = path->nodes[0];
536 }
537 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
538 if (key.objectid != extent_item_objectid)
539 break;
540 if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
541 dref = btrfs_item_ptr(eb, path->slots[0],
542 struct btrfs_extent_data_ref);
543 ret = __data_list_add_eb(&data_refs, eb, dref);
544 } else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
545 ret = __shared_list_add(&shared_refs, key.offset);
546 }
547 }
548
549 btrfs_release_path(path);
550
551 /*
552 * ... only at the very end we can process the refs we found. this is
553 * because the iterator function we call is allowed to make tree lookups
554 * and we have to avoid deadlocks. additionally, we need more tree
555 * lookups ourselves for shared data refs.
556 */
557 while (!list_empty(&data_refs)) {
558 ref_d = list_first_entry(&data_refs, struct __data_ref, list);
559 list_del(&ref_d->list);
560 if (!ret)
561 ret = iterate(ref_d->inum, extent_offset +
562 ref_d->extent_data_item_offset,
563 ref_d->root, ctx);
564 kfree(ref_d);
565 }
566
567 while (!list_empty(&shared_refs)) {
568 ref_s = list_first_entry(&shared_refs, struct __shared_ref,
569 list);
570 list_del(&ref_s->list);
571 if (!ret)
572 ret = __iter_shared_inline_ref(fs_info,
573 ref_s->disk_byte,
574 extent_item_objectid,
575 extent_offset, path,
576 &data_refs,
577 iterate, ctx);
578 kfree(ref_s);
579 }
580
581 return ret;
582}
583
584int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
585 struct btrfs_path *path,
586 iterate_extent_inodes_t *iterate, void *ctx)
587{
588 int ret;
589 u64 offset;
590 struct btrfs_key found_key;
591
592 ret = extent_from_logical(fs_info, logical, path,
593 &found_key);
594 if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
595 ret = -EINVAL;
596 if (ret < 0)
597 return ret;
598
599 offset = logical - found_key.objectid;
600 ret = iterate_extent_inodes(fs_info, path, found_key.objectid,
601 offset, iterate, ctx);
602
603 return ret;
604}
605
606static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
607 struct btrfs_path *path,
608 iterate_irefs_t *iterate, void *ctx)
609{
610 int ret;
611 int slot;
612 u32 cur;
613 u32 len;
614 u32 name_len;
615 u64 parent = 0;
616 int found = 0;
617 struct extent_buffer *eb;
618 struct btrfs_item *item;
619 struct btrfs_inode_ref *iref;
620 struct btrfs_key found_key;
621
622 while (1) {
623 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
624 &found_key);
625 if (ret < 0)
626 break;
627 if (ret) {
628 ret = found ? 0 : -ENOENT;
629 break;
630 }
631 ++found;
632
633 parent = found_key.offset;
634 slot = path->slots[0];
635 eb = path->nodes[0];
636 /* make sure we can use eb after releasing the path */
637 atomic_inc(&eb->refs);
638 btrfs_release_path(path);
639
640 item = btrfs_item_nr(eb, slot);
641 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
642
643 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
644 name_len = btrfs_inode_ref_name_len(eb, iref);
645 /* path must be released before calling iterate()! */
646 ret = iterate(parent, iref, eb, ctx);
647 if (ret) {
648 free_extent_buffer(eb);
649 break;
650 }
651 len = sizeof(*iref) + name_len;
652 iref = (struct btrfs_inode_ref *)((char *)iref + len);
653 }
654 free_extent_buffer(eb);
655 }
656
657 btrfs_release_path(path);
658
659 return ret;
660}
661
662/*
663 * returns 0 if the path could be dumped (probably truncated)
664 * returns <0 in case of an error
665 */
666static int inode_to_path(u64 inum, struct btrfs_inode_ref *iref,
667 struct extent_buffer *eb, void *ctx)
668{
669 struct inode_fs_paths *ipath = ctx;
670 char *fspath;
671 char *fspath_min;
672 int i = ipath->fspath->elem_cnt;
673 const int s_ptr = sizeof(char *);
674 u32 bytes_left;
675
676 bytes_left = ipath->fspath->bytes_left > s_ptr ?
677 ipath->fspath->bytes_left - s_ptr : 0;
678
679 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
680 fspath = iref_to_path(ipath->fs_root, ipath->btrfs_path, iref, eb,
681 inum, fspath_min, bytes_left);
682 if (IS_ERR(fspath))
683 return PTR_ERR(fspath);
684
685 if (fspath > fspath_min) {
686 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
687 ++ipath->fspath->elem_cnt;
688 ipath->fspath->bytes_left = fspath - fspath_min;
689 } else {
690 ++ipath->fspath->elem_missed;
691 ipath->fspath->bytes_missing += fspath_min - fspath;
692 ipath->fspath->bytes_left = 0;
693 }
694
695 return 0;
696}
697
698/*
699 * this dumps all file system paths to the inode into the ipath struct, provided
700 * is has been created large enough. each path is zero-terminated and accessed
701 * from ipath->fspath->val[i].
702 * when it returns, there are ipath->fspath->elem_cnt number of paths available
703 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
704 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
705 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
706 * have been needed to return all paths.
707 */
708int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
709{
710 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
711 inode_to_path, ipath);
712}
713
714/*
715 * allocates space to return multiple file system paths for an inode.
716 * total_bytes to allocate are passed, note that space usable for actual path
717 * information will be total_bytes - sizeof(struct inode_fs_paths).
718 * the returned pointer must be freed with free_ipath() in the end.
719 */
720struct btrfs_data_container *init_data_container(u32 total_bytes)
721{
722 struct btrfs_data_container *data;
723 size_t alloc_bytes;
724
725 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
726 data = kmalloc(alloc_bytes, GFP_NOFS);
727 if (!data)
728 return ERR_PTR(-ENOMEM);
729
730 if (total_bytes >= sizeof(*data)) {
731 data->bytes_left = total_bytes - sizeof(*data);
732 data->bytes_missing = 0;
733 } else {
734 data->bytes_missing = sizeof(*data) - total_bytes;
735 data->bytes_left = 0;
736 }
737
738 data->elem_cnt = 0;
739 data->elem_missed = 0;
740
741 return data;
742}
743
744/*
745 * allocates space to return multiple file system paths for an inode.
746 * total_bytes to allocate are passed, note that space usable for actual path
747 * information will be total_bytes - sizeof(struct inode_fs_paths).
748 * the returned pointer must be freed with free_ipath() in the end.
749 */
750struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
751 struct btrfs_path *path)
752{
753 struct inode_fs_paths *ifp;
754 struct btrfs_data_container *fspath;
755
756 fspath = init_data_container(total_bytes);
757 if (IS_ERR(fspath))
758 return (void *)fspath;
759
760 ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
761 if (!ifp) {
762 kfree(fspath);
763 return ERR_PTR(-ENOMEM);
764 }
765
766 ifp->btrfs_path = path;
767 ifp->fspath = fspath;
768 ifp->fs_root = fs_root;
769
770 return ifp;
771}
772
773void free_ipath(struct inode_fs_paths *ipath)
774{
775 kfree(ipath);
776}
generated by cgit v1.2.2 (git 2.25.0) at 2025-12-30 21:22:35 -0500