cw1200: When debug is enabled, display all wakeup conditions for the wait_event_inter...
[firefly-linux-kernel-4.4.55.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 data_offset;
40         u64 data_len;
41         struct extent_inode_elem *e;
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
50         e = kmalloc(sizeof(*e), GFP_NOFS);
51         if (!e)
52                 return -ENOMEM;
53
54         e->next = *eie;
55         e->inum = key->objectid;
56         e->offset = key->offset + (extent_item_pos - data_offset);
57         *eie = e;
58
59         return 0;
60 }
61
62 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
63                                 u64 extent_item_pos,
64                                 struct extent_inode_elem **eie)
65 {
66         u64 disk_byte;
67         struct btrfs_key key;
68         struct btrfs_file_extent_item *fi;
69         int slot;
70         int nritems;
71         int extent_type;
72         int ret;
73
74         /*
75          * from the shared data ref, we only have the leaf but we need
76          * the key. thus, we must look into all items and see that we
77          * find one (some) with a reference to our extent item.
78          */
79         nritems = btrfs_header_nritems(eb);
80         for (slot = 0; slot < nritems; ++slot) {
81                 btrfs_item_key_to_cpu(eb, &key, slot);
82                 if (key.type != BTRFS_EXTENT_DATA_KEY)
83                         continue;
84                 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
85                 extent_type = btrfs_file_extent_type(eb, fi);
86                 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
87                         continue;
88                 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
89                 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
90                 if (disk_byte != wanted_disk_byte)
91                         continue;
92
93                 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
94                 if (ret < 0)
95                         return ret;
96         }
97
98         return 0;
99 }
100
101 /*
102  * this structure records all encountered refs on the way up to the root
103  */
104 struct __prelim_ref {
105         struct list_head list;
106         u64 root_id;
107         struct btrfs_key key_for_search;
108         int level;
109         int count;
110         struct extent_inode_elem *inode_list;
111         u64 parent;
112         u64 wanted_disk_byte;
113 };
114
115 /*
116  * the rules for all callers of this function are:
117  * - obtaining the parent is the goal
118  * - if you add a key, you must know that it is a correct key
119  * - if you cannot add the parent or a correct key, then we will look into the
120  *   block later to set a correct key
121  *
122  * delayed refs
123  * ============
124  *        backref type | shared | indirect | shared | indirect
125  * information         |   tree |     tree |   data |     data
126  * --------------------+--------+----------+--------+----------
127  *      parent logical |    y   |     -    |    -   |     -
128  *      key to resolve |    -   |     y    |    y   |     y
129  *  tree block logical |    -   |     -    |    -   |     -
130  *  root for resolving |    y   |     y    |    y   |     y
131  *
132  * - column 1:       we've the parent -> done
133  * - column 2, 3, 4: we use the key to find the parent
134  *
135  * on disk refs (inline or keyed)
136  * ==============================
137  *        backref type | shared | indirect | shared | indirect
138  * information         |   tree |     tree |   data |     data
139  * --------------------+--------+----------+--------+----------
140  *      parent logical |    y   |     -    |    y   |     -
141  *      key to resolve |    -   |     -    |    -   |     y
142  *  tree block logical |    y   |     y    |    y   |     y
143  *  root for resolving |    -   |     y    |    y   |     y
144  *
145  * - column 1, 3: we've the parent -> done
146  * - column 2:    we take the first key from the block to find the parent
147  *                (see __add_missing_keys)
148  * - column 4:    we use the key to find the parent
149  *
150  * additional information that's available but not required to find the parent
151  * block might help in merging entries to gain some speed.
152  */
153
154 static int __add_prelim_ref(struct list_head *head, u64 root_id,
155                             struct btrfs_key *key, int level,
156                             u64 parent, u64 wanted_disk_byte, int count)
157 {
158         struct __prelim_ref *ref;
159
160         /* in case we're adding delayed refs, we're holding the refs spinlock */
161         ref = kmalloc(sizeof(*ref), GFP_ATOMIC);
162         if (!ref)
163                 return -ENOMEM;
164
165         ref->root_id = root_id;
166         if (key)
167                 ref->key_for_search = *key;
168         else
169                 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
170
171         ref->inode_list = NULL;
172         ref->level = level;
173         ref->count = count;
174         ref->parent = parent;
175         ref->wanted_disk_byte = wanted_disk_byte;
176         list_add_tail(&ref->list, head);
177
178         return 0;
179 }
180
181 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
182                                 struct ulist *parents, int level,
183                                 struct btrfs_key *key_for_search, u64 time_seq,
184                                 u64 wanted_disk_byte,
185                                 const u64 *extent_item_pos)
186 {
187         int ret = 0;
188         int slot;
189         struct extent_buffer *eb;
190         struct btrfs_key key;
191         struct btrfs_file_extent_item *fi;
192         struct extent_inode_elem *eie = NULL;
193         u64 disk_byte;
194
195         if (level != 0) {
196                 eb = path->nodes[level];
197                 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
198                 if (ret < 0)
199                         return ret;
200                 return 0;
201         }
202
203         /*
204          * We normally enter this function with the path already pointing to
205          * the first item to check. But sometimes, we may enter it with
206          * slot==nritems. In that case, go to the next leaf before we continue.
207          */
208         if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
209                 ret = btrfs_next_old_leaf(root, path, time_seq);
210
211         while (!ret) {
212                 eb = path->nodes[0];
213                 slot = path->slots[0];
214
215                 btrfs_item_key_to_cpu(eb, &key, slot);
216
217                 if (key.objectid != key_for_search->objectid ||
218                     key.type != BTRFS_EXTENT_DATA_KEY)
219                         break;
220
221                 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
222                 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
223
224                 if (disk_byte == wanted_disk_byte) {
225                         eie = NULL;
226                         if (extent_item_pos) {
227                                 ret = check_extent_in_eb(&key, eb, fi,
228                                                 *extent_item_pos,
229                                                 &eie);
230                                 if (ret < 0)
231                                         break;
232                         }
233                         if (!ret) {
234                                 ret = ulist_add(parents, eb->start,
235                                                 (uintptr_t)eie, GFP_NOFS);
236                                 if (ret < 0)
237                                         break;
238                                 if (!extent_item_pos) {
239                                         ret = btrfs_next_old_leaf(root, path,
240                                                         time_seq);
241                                         continue;
242                                 }
243                         }
244                 }
245                 ret = btrfs_next_old_item(root, path, time_seq);
246         }
247
248         if (ret > 0)
249                 ret = 0;
250         return ret;
251 }
252
253 /*
254  * resolve an indirect backref in the form (root_id, key, level)
255  * to a logical address
256  */
257 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
258                                   struct btrfs_path *path, u64 time_seq,
259                                   struct __prelim_ref *ref,
260                                   struct ulist *parents,
261                                   const u64 *extent_item_pos)
262 {
263         struct btrfs_root *root;
264         struct btrfs_key root_key;
265         struct extent_buffer *eb;
266         int ret = 0;
267         int root_level;
268         int level = ref->level;
269
270         root_key.objectid = ref->root_id;
271         root_key.type = BTRFS_ROOT_ITEM_KEY;
272         root_key.offset = (u64)-1;
273         root = btrfs_read_fs_root_no_name(fs_info, &root_key);
274         if (IS_ERR(root)) {
275                 ret = PTR_ERR(root);
276                 goto out;
277         }
278
279         root_level = btrfs_old_root_level(root, time_seq);
280
281         if (root_level + 1 == level)
282                 goto out;
283
284         path->lowest_level = level;
285         ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
286         pr_debug("search slot in root %llu (level %d, ref count %d) returned "
287                  "%d for key (%llu %u %llu)\n",
288                  (unsigned long long)ref->root_id, level, ref->count, ret,
289                  (unsigned long long)ref->key_for_search.objectid,
290                  ref->key_for_search.type,
291                  (unsigned long long)ref->key_for_search.offset);
292         if (ret < 0)
293                 goto out;
294
295         eb = path->nodes[level];
296         while (!eb) {
297                 if (!level) {
298                         WARN_ON(1);
299                         ret = 1;
300                         goto out;
301                 }
302                 level--;
303                 eb = path->nodes[level];
304         }
305
306         ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
307                                 time_seq, ref->wanted_disk_byte,
308                                 extent_item_pos);
309 out:
310         path->lowest_level = 0;
311         btrfs_release_path(path);
312         return ret;
313 }
314
315 /*
316  * resolve all indirect backrefs from the list
317  */
318 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
319                                    struct btrfs_path *path, u64 time_seq,
320                                    struct list_head *head,
321                                    const u64 *extent_item_pos)
322 {
323         int err;
324         int ret = 0;
325         struct __prelim_ref *ref;
326         struct __prelim_ref *ref_safe;
327         struct __prelim_ref *new_ref;
328         struct ulist *parents;
329         struct ulist_node *node;
330         struct ulist_iterator uiter;
331
332         parents = ulist_alloc(GFP_NOFS);
333         if (!parents)
334                 return -ENOMEM;
335
336         /*
337          * _safe allows us to insert directly after the current item without
338          * iterating over the newly inserted items.
339          * we're also allowed to re-assign ref during iteration.
340          */
341         list_for_each_entry_safe(ref, ref_safe, head, list) {
342                 if (ref->parent)        /* already direct */
343                         continue;
344                 if (ref->count == 0)
345                         continue;
346                 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
347                                              parents, extent_item_pos);
348                 if (err == -ENOMEM)
349                         goto out;
350                 if (err)
351                         continue;
352
353                 /* we put the first parent into the ref at hand */
354                 ULIST_ITER_INIT(&uiter);
355                 node = ulist_next(parents, &uiter);
356                 ref->parent = node ? node->val : 0;
357                 ref->inode_list = node ?
358                         (struct extent_inode_elem *)(uintptr_t)node->aux : 0;
359
360                 /* additional parents require new refs being added here */
361                 while ((node = ulist_next(parents, &uiter))) {
362                         new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
363                         if (!new_ref) {
364                                 ret = -ENOMEM;
365                                 goto out;
366                         }
367                         memcpy(new_ref, ref, sizeof(*ref));
368                         new_ref->parent = node->val;
369                         new_ref->inode_list = (struct extent_inode_elem *)
370                                                         (uintptr_t)node->aux;
371                         list_add(&new_ref->list, &ref->list);
372                 }
373                 ulist_reinit(parents);
374         }
375 out:
376         ulist_free(parents);
377         return ret;
378 }
379
380 static inline int ref_for_same_block(struct __prelim_ref *ref1,
381                                      struct __prelim_ref *ref2)
382 {
383         if (ref1->level != ref2->level)
384                 return 0;
385         if (ref1->root_id != ref2->root_id)
386                 return 0;
387         if (ref1->key_for_search.type != ref2->key_for_search.type)
388                 return 0;
389         if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
390                 return 0;
391         if (ref1->key_for_search.offset != ref2->key_for_search.offset)
392                 return 0;
393         if (ref1->parent != ref2->parent)
394                 return 0;
395
396         return 1;
397 }
398
399 /*
400  * read tree blocks and add keys where required.
401  */
402 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
403                               struct list_head *head)
404 {
405         struct list_head *pos;
406         struct extent_buffer *eb;
407
408         list_for_each(pos, head) {
409                 struct __prelim_ref *ref;
410                 ref = list_entry(pos, struct __prelim_ref, list);
411
412                 if (ref->parent)
413                         continue;
414                 if (ref->key_for_search.type)
415                         continue;
416                 BUG_ON(!ref->wanted_disk_byte);
417                 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
418                                      fs_info->tree_root->leafsize, 0);
419                 if (!eb || !extent_buffer_uptodate(eb)) {
420                         free_extent_buffer(eb);
421                         return -EIO;
422                 }
423                 btrfs_tree_read_lock(eb);
424                 if (btrfs_header_level(eb) == 0)
425                         btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
426                 else
427                         btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
428                 btrfs_tree_read_unlock(eb);
429                 free_extent_buffer(eb);
430         }
431         return 0;
432 }
433
434 /*
435  * merge two lists of backrefs and adjust counts accordingly
436  *
437  * mode = 1: merge identical keys, if key is set
438  *    FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
439  *           additionally, we could even add a key range for the blocks we
440  *           looked into to merge even more (-> replace unresolved refs by those
441  *           having a parent).
442  * mode = 2: merge identical parents
443  */
444 static void __merge_refs(struct list_head *head, int mode)
445 {
446         struct list_head *pos1;
447
448         list_for_each(pos1, head) {
449                 struct list_head *n2;
450                 struct list_head *pos2;
451                 struct __prelim_ref *ref1;
452
453                 ref1 = list_entry(pos1, struct __prelim_ref, list);
454
455                 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
456                      pos2 = n2, n2 = pos2->next) {
457                         struct __prelim_ref *ref2;
458                         struct __prelim_ref *xchg;
459                         struct extent_inode_elem *eie;
460
461                         ref2 = list_entry(pos2, struct __prelim_ref, list);
462
463                         if (mode == 1) {
464                                 if (!ref_for_same_block(ref1, ref2))
465                                         continue;
466                                 if (!ref1->parent && ref2->parent) {
467                                         xchg = ref1;
468                                         ref1 = ref2;
469                                         ref2 = xchg;
470                                 }
471                         } else {
472                                 if (ref1->parent != ref2->parent)
473                                         continue;
474                         }
475
476                         eie = ref1->inode_list;
477                         while (eie && eie->next)
478                                 eie = eie->next;
479                         if (eie)
480                                 eie->next = ref2->inode_list;
481                         else
482                                 ref1->inode_list = ref2->inode_list;
483                         ref1->count += ref2->count;
484
485                         list_del(&ref2->list);
486                         kfree(ref2);
487                 }
488
489         }
490 }
491
492 /*
493  * add all currently queued delayed refs from this head whose seq nr is
494  * smaller or equal that seq to the list
495  */
496 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
497                               struct list_head *prefs)
498 {
499         struct btrfs_delayed_extent_op *extent_op = head->extent_op;
500         struct rb_node *n = &head->node.rb_node;
501         struct btrfs_key key;
502         struct btrfs_key op_key = {0};
503         int sgn;
504         int ret = 0;
505
506         if (extent_op && extent_op->update_key)
507                 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
508
509         while ((n = rb_prev(n))) {
510                 struct btrfs_delayed_ref_node *node;
511                 node = rb_entry(n, struct btrfs_delayed_ref_node,
512                                 rb_node);
513                 if (node->bytenr != head->node.bytenr)
514                         break;
515                 WARN_ON(node->is_head);
516
517                 if (node->seq > seq)
518                         continue;
519
520                 switch (node->action) {
521                 case BTRFS_ADD_DELAYED_EXTENT:
522                 case BTRFS_UPDATE_DELAYED_HEAD:
523                         WARN_ON(1);
524                         continue;
525                 case BTRFS_ADD_DELAYED_REF:
526                         sgn = 1;
527                         break;
528                 case BTRFS_DROP_DELAYED_REF:
529                         sgn = -1;
530                         break;
531                 default:
532                         BUG_ON(1);
533                 }
534                 switch (node->type) {
535                 case BTRFS_TREE_BLOCK_REF_KEY: {
536                         struct btrfs_delayed_tree_ref *ref;
537
538                         ref = btrfs_delayed_node_to_tree_ref(node);
539                         ret = __add_prelim_ref(prefs, ref->root, &op_key,
540                                                ref->level + 1, 0, node->bytenr,
541                                                node->ref_mod * sgn);
542                         break;
543                 }
544                 case BTRFS_SHARED_BLOCK_REF_KEY: {
545                         struct btrfs_delayed_tree_ref *ref;
546
547                         ref = btrfs_delayed_node_to_tree_ref(node);
548                         ret = __add_prelim_ref(prefs, ref->root, NULL,
549                                                ref->level + 1, ref->parent,
550                                                node->bytenr,
551                                                node->ref_mod * sgn);
552                         break;
553                 }
554                 case BTRFS_EXTENT_DATA_REF_KEY: {
555                         struct btrfs_delayed_data_ref *ref;
556                         ref = btrfs_delayed_node_to_data_ref(node);
557
558                         key.objectid = ref->objectid;
559                         key.type = BTRFS_EXTENT_DATA_KEY;
560                         key.offset = ref->offset;
561                         ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
562                                                node->bytenr,
563                                                node->ref_mod * sgn);
564                         break;
565                 }
566                 case BTRFS_SHARED_DATA_REF_KEY: {
567                         struct btrfs_delayed_data_ref *ref;
568
569                         ref = btrfs_delayed_node_to_data_ref(node);
570
571                         key.objectid = ref->objectid;
572                         key.type = BTRFS_EXTENT_DATA_KEY;
573                         key.offset = ref->offset;
574                         ret = __add_prelim_ref(prefs, ref->root, &key, 0,
575                                                ref->parent, node->bytenr,
576                                                node->ref_mod * sgn);
577                         break;
578                 }
579                 default:
580                         WARN_ON(1);
581                 }
582                 if (ret)
583                         return ret;
584         }
585
586         return 0;
587 }
588
589 /*
590  * add all inline backrefs for bytenr to the list
591  */
592 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
593                              struct btrfs_path *path, u64 bytenr,
594                              int *info_level, struct list_head *prefs)
595 {
596         int ret = 0;
597         int slot;
598         struct extent_buffer *leaf;
599         struct btrfs_key key;
600         struct btrfs_key found_key;
601         unsigned long ptr;
602         unsigned long end;
603         struct btrfs_extent_item *ei;
604         u64 flags;
605         u64 item_size;
606
607         /*
608          * enumerate all inline refs
609          */
610         leaf = path->nodes[0];
611         slot = path->slots[0];
612
613         item_size = btrfs_item_size_nr(leaf, slot);
614         BUG_ON(item_size < sizeof(*ei));
615
616         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
617         flags = btrfs_extent_flags(leaf, ei);
618         btrfs_item_key_to_cpu(leaf, &found_key, slot);
619
620         ptr = (unsigned long)(ei + 1);
621         end = (unsigned long)ei + item_size;
622
623         if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
624             flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
625                 struct btrfs_tree_block_info *info;
626
627                 info = (struct btrfs_tree_block_info *)ptr;
628                 *info_level = btrfs_tree_block_level(leaf, info);
629                 ptr += sizeof(struct btrfs_tree_block_info);
630                 BUG_ON(ptr > end);
631         } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
632                 *info_level = found_key.offset;
633         } else {
634                 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
635         }
636
637         while (ptr < end) {
638                 struct btrfs_extent_inline_ref *iref;
639                 u64 offset;
640                 int type;
641
642                 iref = (struct btrfs_extent_inline_ref *)ptr;
643                 type = btrfs_extent_inline_ref_type(leaf, iref);
644                 offset = btrfs_extent_inline_ref_offset(leaf, iref);
645
646                 switch (type) {
647                 case BTRFS_SHARED_BLOCK_REF_KEY:
648                         ret = __add_prelim_ref(prefs, 0, NULL,
649                                                 *info_level + 1, offset,
650                                                 bytenr, 1);
651                         break;
652                 case BTRFS_SHARED_DATA_REF_KEY: {
653                         struct btrfs_shared_data_ref *sdref;
654                         int count;
655
656                         sdref = (struct btrfs_shared_data_ref *)(iref + 1);
657                         count = btrfs_shared_data_ref_count(leaf, sdref);
658                         ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
659                                                bytenr, count);
660                         break;
661                 }
662                 case BTRFS_TREE_BLOCK_REF_KEY:
663                         ret = __add_prelim_ref(prefs, offset, NULL,
664                                                *info_level + 1, 0,
665                                                bytenr, 1);
666                         break;
667                 case BTRFS_EXTENT_DATA_REF_KEY: {
668                         struct btrfs_extent_data_ref *dref;
669                         int count;
670                         u64 root;
671
672                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
673                         count = btrfs_extent_data_ref_count(leaf, dref);
674                         key.objectid = btrfs_extent_data_ref_objectid(leaf,
675                                                                       dref);
676                         key.type = BTRFS_EXTENT_DATA_KEY;
677                         key.offset = btrfs_extent_data_ref_offset(leaf, dref);
678                         root = btrfs_extent_data_ref_root(leaf, dref);
679                         ret = __add_prelim_ref(prefs, root, &key, 0, 0,
680                                                bytenr, count);
681                         break;
682                 }
683                 default:
684                         WARN_ON(1);
685                 }
686                 if (ret)
687                         return ret;
688                 ptr += btrfs_extent_inline_ref_size(type);
689         }
690
691         return 0;
692 }
693
694 /*
695  * add all non-inline backrefs for bytenr to the list
696  */
697 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
698                             struct btrfs_path *path, u64 bytenr,
699                             int info_level, struct list_head *prefs)
700 {
701         struct btrfs_root *extent_root = fs_info->extent_root;
702         int ret;
703         int slot;
704         struct extent_buffer *leaf;
705         struct btrfs_key key;
706
707         while (1) {
708                 ret = btrfs_next_item(extent_root, path);
709                 if (ret < 0)
710                         break;
711                 if (ret) {
712                         ret = 0;
713                         break;
714                 }
715
716                 slot = path->slots[0];
717                 leaf = path->nodes[0];
718                 btrfs_item_key_to_cpu(leaf, &key, slot);
719
720                 if (key.objectid != bytenr)
721                         break;
722                 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
723                         continue;
724                 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
725                         break;
726
727                 switch (key.type) {
728                 case BTRFS_SHARED_BLOCK_REF_KEY:
729                         ret = __add_prelim_ref(prefs, 0, NULL,
730                                                 info_level + 1, key.offset,
731                                                 bytenr, 1);
732                         break;
733                 case BTRFS_SHARED_DATA_REF_KEY: {
734                         struct btrfs_shared_data_ref *sdref;
735                         int count;
736
737                         sdref = btrfs_item_ptr(leaf, slot,
738                                               struct btrfs_shared_data_ref);
739                         count = btrfs_shared_data_ref_count(leaf, sdref);
740                         ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
741                                                 bytenr, count);
742                         break;
743                 }
744                 case BTRFS_TREE_BLOCK_REF_KEY:
745                         ret = __add_prelim_ref(prefs, key.offset, NULL,
746                                                info_level + 1, 0,
747                                                bytenr, 1);
748                         break;
749                 case BTRFS_EXTENT_DATA_REF_KEY: {
750                         struct btrfs_extent_data_ref *dref;
751                         int count;
752                         u64 root;
753
754                         dref = btrfs_item_ptr(leaf, slot,
755                                               struct btrfs_extent_data_ref);
756                         count = btrfs_extent_data_ref_count(leaf, dref);
757                         key.objectid = btrfs_extent_data_ref_objectid(leaf,
758                                                                       dref);
759                         key.type = BTRFS_EXTENT_DATA_KEY;
760                         key.offset = btrfs_extent_data_ref_offset(leaf, dref);
761                         root = btrfs_extent_data_ref_root(leaf, dref);
762                         ret = __add_prelim_ref(prefs, root, &key, 0, 0,
763                                                bytenr, count);
764                         break;
765                 }
766                 default:
767                         WARN_ON(1);
768                 }
769                 if (ret)
770                         return ret;
771
772         }
773
774         return ret;
775 }
776
777 /*
778  * this adds all existing backrefs (inline backrefs, backrefs and delayed
779  * refs) for the given bytenr to the refs list, merges duplicates and resolves
780  * indirect refs to their parent bytenr.
781  * When roots are found, they're added to the roots list
782  *
783  * FIXME some caching might speed things up
784  */
785 static int find_parent_nodes(struct btrfs_trans_handle *trans,
786                              struct btrfs_fs_info *fs_info, u64 bytenr,
787                              u64 time_seq, struct ulist *refs,
788                              struct ulist *roots, const u64 *extent_item_pos)
789 {
790         struct btrfs_key key;
791         struct btrfs_path *path;
792         struct btrfs_delayed_ref_root *delayed_refs = NULL;
793         struct btrfs_delayed_ref_head *head;
794         int info_level = 0;
795         int ret;
796         struct list_head prefs_delayed;
797         struct list_head prefs;
798         struct __prelim_ref *ref;
799
800         INIT_LIST_HEAD(&prefs);
801         INIT_LIST_HEAD(&prefs_delayed);
802
803         key.objectid = bytenr;
804         key.offset = (u64)-1;
805         if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
806                 key.type = BTRFS_METADATA_ITEM_KEY;
807         else
808                 key.type = BTRFS_EXTENT_ITEM_KEY;
809
810         path = btrfs_alloc_path();
811         if (!path)
812                 return -ENOMEM;
813         if (!trans)
814                 path->search_commit_root = 1;
815
816         /*
817          * grab both a lock on the path and a lock on the delayed ref head.
818          * We need both to get a consistent picture of how the refs look
819          * at a specified point in time
820          */
821 again:
822         head = NULL;
823
824         ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
825         if (ret < 0)
826                 goto out;
827         BUG_ON(ret == 0);
828
829         if (trans) {
830                 /*
831                  * look if there are updates for this ref queued and lock the
832                  * head
833                  */
834                 delayed_refs = &trans->transaction->delayed_refs;
835                 spin_lock(&delayed_refs->lock);
836                 head = btrfs_find_delayed_ref_head(trans, bytenr);
837                 if (head) {
838                         if (!mutex_trylock(&head->mutex)) {
839                                 atomic_inc(&head->node.refs);
840                                 spin_unlock(&delayed_refs->lock);
841
842                                 btrfs_release_path(path);
843
844                                 /*
845                                  * Mutex was contended, block until it's
846                                  * released and try again
847                                  */
848                                 mutex_lock(&head->mutex);
849                                 mutex_unlock(&head->mutex);
850                                 btrfs_put_delayed_ref(&head->node);
851                                 goto again;
852                         }
853                         ret = __add_delayed_refs(head, time_seq,
854                                                  &prefs_delayed);
855                         mutex_unlock(&head->mutex);
856                         if (ret) {
857                                 spin_unlock(&delayed_refs->lock);
858                                 goto out;
859                         }
860                 }
861                 spin_unlock(&delayed_refs->lock);
862         }
863
864         if (path->slots[0]) {
865                 struct extent_buffer *leaf;
866                 int slot;
867
868                 path->slots[0]--;
869                 leaf = path->nodes[0];
870                 slot = path->slots[0];
871                 btrfs_item_key_to_cpu(leaf, &key, slot);
872                 if (key.objectid == bytenr &&
873                     (key.type == BTRFS_EXTENT_ITEM_KEY ||
874                      key.type == BTRFS_METADATA_ITEM_KEY)) {
875                         ret = __add_inline_refs(fs_info, path, bytenr,
876                                                 &info_level, &prefs);
877                         if (ret)
878                                 goto out;
879                         ret = __add_keyed_refs(fs_info, path, bytenr,
880                                                info_level, &prefs);
881                         if (ret)
882                                 goto out;
883                 }
884         }
885         btrfs_release_path(path);
886
887         list_splice_init(&prefs_delayed, &prefs);
888
889         ret = __add_missing_keys(fs_info, &prefs);
890         if (ret)
891                 goto out;
892
893         __merge_refs(&prefs, 1);
894
895         ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
896                                       extent_item_pos);
897         if (ret)
898                 goto out;
899
900         __merge_refs(&prefs, 2);
901
902         while (!list_empty(&prefs)) {
903                 ref = list_first_entry(&prefs, struct __prelim_ref, list);
904                 list_del(&ref->list);
905                 WARN_ON(ref->count < 0);
906                 if (ref->count && ref->root_id && ref->parent == 0) {
907                         /* no parent == root of tree */
908                         ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
909                         if (ret < 0)
910                                 goto out;
911                 }
912                 if (ref->count && ref->parent) {
913                         struct extent_inode_elem *eie = NULL;
914                         if (extent_item_pos && !ref->inode_list) {
915                                 u32 bsz;
916                                 struct extent_buffer *eb;
917                                 bsz = btrfs_level_size(fs_info->extent_root,
918                                                         info_level);
919                                 eb = read_tree_block(fs_info->extent_root,
920                                                            ref->parent, bsz, 0);
921                                 if (!eb || !extent_buffer_uptodate(eb)) {
922                                         free_extent_buffer(eb);
923                                         ret = -EIO;
924                                         goto out;
925                                 }
926                                 ret = find_extent_in_eb(eb, bytenr,
927                                                         *extent_item_pos, &eie);
928                                 ref->inode_list = eie;
929                                 free_extent_buffer(eb);
930                         }
931                         ret = ulist_add_merge(refs, ref->parent,
932                                               (uintptr_t)ref->inode_list,
933                                               (u64 *)&eie, GFP_NOFS);
934                         if (ret < 0)
935                                 goto out;
936                         if (!ret && extent_item_pos) {
937                                 /*
938                                  * we've recorded that parent, so we must extend
939                                  * its inode list here
940                                  */
941                                 BUG_ON(!eie);
942                                 while (eie->next)
943                                         eie = eie->next;
944                                 eie->next = ref->inode_list;
945                         }
946                 }
947                 kfree(ref);
948         }
949
950 out:
951         btrfs_free_path(path);
952         while (!list_empty(&prefs)) {
953                 ref = list_first_entry(&prefs, struct __prelim_ref, list);
954                 list_del(&ref->list);
955                 kfree(ref);
956         }
957         while (!list_empty(&prefs_delayed)) {
958                 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
959                                        list);
960                 list_del(&ref->list);
961                 kfree(ref);
962         }
963
964         return ret;
965 }
966
967 static void free_leaf_list(struct ulist *blocks)
968 {
969         struct ulist_node *node = NULL;
970         struct extent_inode_elem *eie;
971         struct extent_inode_elem *eie_next;
972         struct ulist_iterator uiter;
973
974         ULIST_ITER_INIT(&uiter);
975         while ((node = ulist_next(blocks, &uiter))) {
976                 if (!node->aux)
977                         continue;
978                 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
979                 for (; eie; eie = eie_next) {
980                         eie_next = eie->next;
981                         kfree(eie);
982                 }
983                 node->aux = 0;
984         }
985
986         ulist_free(blocks);
987 }
988
989 /*
990  * Finds all leafs with a reference to the specified combination of bytenr and
991  * offset. key_list_head will point to a list of corresponding keys (caller must
992  * free each list element). The leafs will be stored in the leafs ulist, which
993  * must be freed with ulist_free.
994  *
995  * returns 0 on success, <0 on error
996  */
997 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
998                                 struct btrfs_fs_info *fs_info, u64 bytenr,
999                                 u64 time_seq, struct ulist **leafs,
1000                                 const u64 *extent_item_pos)
1001 {
1002         struct ulist *tmp;
1003         int ret;
1004
1005         tmp = ulist_alloc(GFP_NOFS);
1006         if (!tmp)
1007                 return -ENOMEM;
1008         *leafs = ulist_alloc(GFP_NOFS);
1009         if (!*leafs) {
1010                 ulist_free(tmp);
1011                 return -ENOMEM;
1012         }
1013
1014         ret = find_parent_nodes(trans, fs_info, bytenr,
1015                                 time_seq, *leafs, tmp, extent_item_pos);
1016         ulist_free(tmp);
1017
1018         if (ret < 0 && ret != -ENOENT) {
1019                 free_leaf_list(*leafs);
1020                 return ret;
1021         }
1022
1023         return 0;
1024 }
1025
1026 /*
1027  * walk all backrefs for a given extent to find all roots that reference this
1028  * extent. Walking a backref means finding all extents that reference this
1029  * extent and in turn walk the backrefs of those, too. Naturally this is a
1030  * recursive process, but here it is implemented in an iterative fashion: We
1031  * find all referencing extents for the extent in question and put them on a
1032  * list. In turn, we find all referencing extents for those, further appending
1033  * to the list. The way we iterate the list allows adding more elements after
1034  * the current while iterating. The process stops when we reach the end of the
1035  * list. Found roots are added to the roots list.
1036  *
1037  * returns 0 on success, < 0 on error.
1038  */
1039 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1040                                 struct btrfs_fs_info *fs_info, u64 bytenr,
1041                                 u64 time_seq, struct ulist **roots)
1042 {
1043         struct ulist *tmp;
1044         struct ulist_node *node = NULL;
1045         struct ulist_iterator uiter;
1046         int ret;
1047
1048         tmp = ulist_alloc(GFP_NOFS);
1049         if (!tmp)
1050                 return -ENOMEM;
1051         *roots = ulist_alloc(GFP_NOFS);
1052         if (!*roots) {
1053                 ulist_free(tmp);
1054                 return -ENOMEM;
1055         }
1056
1057         ULIST_ITER_INIT(&uiter);
1058         while (1) {
1059                 ret = find_parent_nodes(trans, fs_info, bytenr,
1060                                         time_seq, tmp, *roots, NULL);
1061                 if (ret < 0 && ret != -ENOENT) {
1062                         ulist_free(tmp);
1063                         ulist_free(*roots);
1064                         return ret;
1065                 }
1066                 node = ulist_next(tmp, &uiter);
1067                 if (!node)
1068                         break;
1069                 bytenr = node->val;
1070         }
1071
1072         ulist_free(tmp);
1073         return 0;
1074 }
1075
1076
1077 static int __inode_info(u64 inum, u64 ioff, u8 key_type,
1078                         struct btrfs_root *fs_root, struct btrfs_path *path,
1079                         struct btrfs_key *found_key)
1080 {
1081         int ret;
1082         struct btrfs_key key;
1083         struct extent_buffer *eb;
1084
1085         key.type = key_type;
1086         key.objectid = inum;
1087         key.offset = ioff;
1088
1089         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1090         if (ret < 0)
1091                 return ret;
1092
1093         eb = path->nodes[0];
1094         if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1095                 ret = btrfs_next_leaf(fs_root, path);
1096                 if (ret)
1097                         return ret;
1098                 eb = path->nodes[0];
1099         }
1100
1101         btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1102         if (found_key->type != key.type || found_key->objectid != key.objectid)
1103                 return 1;
1104
1105         return 0;
1106 }
1107
1108 /*
1109  * this makes the path point to (inum INODE_ITEM ioff)
1110  */
1111 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1112                         struct btrfs_path *path)
1113 {
1114         struct btrfs_key key;
1115         return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
1116                                 &key);
1117 }
1118
1119 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1120                                 struct btrfs_path *path,
1121                                 struct btrfs_key *found_key)
1122 {
1123         return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
1124                                 found_key);
1125 }
1126
1127 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1128                           u64 start_off, struct btrfs_path *path,
1129                           struct btrfs_inode_extref **ret_extref,
1130                           u64 *found_off)
1131 {
1132         int ret, slot;
1133         struct btrfs_key key;
1134         struct btrfs_key found_key;
1135         struct btrfs_inode_extref *extref;
1136         struct extent_buffer *leaf;
1137         unsigned long ptr;
1138
1139         key.objectid = inode_objectid;
1140         btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1141         key.offset = start_off;
1142
1143         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1144         if (ret < 0)
1145                 return ret;
1146
1147         while (1) {
1148                 leaf = path->nodes[0];
1149                 slot = path->slots[0];
1150                 if (slot >= btrfs_header_nritems(leaf)) {
1151                         /*
1152                          * If the item at offset is not found,
1153                          * btrfs_search_slot will point us to the slot
1154                          * where it should be inserted. In our case
1155                          * that will be the slot directly before the
1156                          * next INODE_REF_KEY_V2 item. In the case
1157                          * that we're pointing to the last slot in a
1158                          * leaf, we must move one leaf over.
1159                          */
1160                         ret = btrfs_next_leaf(root, path);
1161                         if (ret) {
1162                                 if (ret >= 1)
1163                                         ret = -ENOENT;
1164                                 break;
1165                         }
1166                         continue;
1167                 }
1168
1169                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1170
1171                 /*
1172                  * Check that we're still looking at an extended ref key for
1173                  * this particular objectid. If we have different
1174                  * objectid or type then there are no more to be found
1175                  * in the tree and we can exit.
1176                  */
1177                 ret = -ENOENT;
1178                 if (found_key.objectid != inode_objectid)
1179                         break;
1180                 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1181                         break;
1182
1183                 ret = 0;
1184                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1185                 extref = (struct btrfs_inode_extref *)ptr;
1186                 *ret_extref = extref;
1187                 if (found_off)
1188                         *found_off = found_key.offset;
1189                 break;
1190         }
1191
1192         return ret;
1193 }
1194
1195 /*
1196  * this iterates to turn a name (from iref/extref) into a full filesystem path.
1197  * Elements of the path are separated by '/' and the path is guaranteed to be
1198  * 0-terminated. the path is only given within the current file system.
1199  * Therefore, it never starts with a '/'. the caller is responsible to provide
1200  * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1201  * the start point of the resulting string is returned. this pointer is within
1202  * dest, normally.
1203  * in case the path buffer would overflow, the pointer is decremented further
1204  * as if output was written to the buffer, though no more output is actually
1205  * generated. that way, the caller can determine how much space would be
1206  * required for the path to fit into the buffer. in that case, the returned
1207  * value will be smaller than dest. callers must check this!
1208  */
1209 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1210                         u32 name_len, unsigned long name_off,
1211                         struct extent_buffer *eb_in, u64 parent,
1212                         char *dest, u32 size)
1213 {
1214         int slot;
1215         u64 next_inum;
1216         int ret;
1217         s64 bytes_left = ((s64)size) - 1;
1218         struct extent_buffer *eb = eb_in;
1219         struct btrfs_key found_key;
1220         int leave_spinning = path->leave_spinning;
1221         struct btrfs_inode_ref *iref;
1222
1223         if (bytes_left >= 0)
1224                 dest[bytes_left] = '\0';
1225
1226         path->leave_spinning = 1;
1227         while (1) {
1228                 bytes_left -= name_len;
1229                 if (bytes_left >= 0)
1230                         read_extent_buffer(eb, dest + bytes_left,
1231                                            name_off, name_len);
1232                 if (eb != eb_in) {
1233                         btrfs_tree_read_unlock_blocking(eb);
1234                         free_extent_buffer(eb);
1235                 }
1236                 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1237                 if (ret > 0)
1238                         ret = -ENOENT;
1239                 if (ret)
1240                         break;
1241
1242                 next_inum = found_key.offset;
1243
1244                 /* regular exit ahead */
1245                 if (parent == next_inum)
1246                         break;
1247
1248                 slot = path->slots[0];
1249                 eb = path->nodes[0];
1250                 /* make sure we can use eb after releasing the path */
1251                 if (eb != eb_in) {
1252                         atomic_inc(&eb->refs);
1253                         btrfs_tree_read_lock(eb);
1254                         btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1255                 }
1256                 btrfs_release_path(path);
1257                 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1258
1259                 name_len = btrfs_inode_ref_name_len(eb, iref);
1260                 name_off = (unsigned long)(iref + 1);
1261
1262                 parent = next_inum;
1263                 --bytes_left;
1264                 if (bytes_left >= 0)
1265                         dest[bytes_left] = '/';
1266         }
1267
1268         btrfs_release_path(path);
1269         path->leave_spinning = leave_spinning;
1270
1271         if (ret)
1272                 return ERR_PTR(ret);
1273
1274         return dest + bytes_left;
1275 }
1276
1277 /*
1278  * this makes the path point to (logical EXTENT_ITEM *)
1279  * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1280  * tree blocks and <0 on error.
1281  */
1282 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1283                         struct btrfs_path *path, struct btrfs_key *found_key,
1284                         u64 *flags_ret)
1285 {
1286         int ret;
1287         u64 flags;
1288         u64 size = 0;
1289         u32 item_size;
1290         struct extent_buffer *eb;
1291         struct btrfs_extent_item *ei;
1292         struct btrfs_key key;
1293
1294         if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1295                 key.type = BTRFS_METADATA_ITEM_KEY;
1296         else
1297                 key.type = BTRFS_EXTENT_ITEM_KEY;
1298         key.objectid = logical;
1299         key.offset = (u64)-1;
1300
1301         ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1302         if (ret < 0)
1303                 return ret;
1304         ret = btrfs_previous_item(fs_info->extent_root, path,
1305                                         0, BTRFS_EXTENT_ITEM_KEY);
1306         if (ret < 0)
1307                 return ret;
1308
1309         btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1310         if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1311                 size = fs_info->extent_root->leafsize;
1312         else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1313                 size = found_key->offset;
1314
1315         if ((found_key->type != BTRFS_EXTENT_ITEM_KEY &&
1316              found_key->type != BTRFS_METADATA_ITEM_KEY) ||
1317             found_key->objectid > logical ||
1318             found_key->objectid + size <= logical) {
1319                 pr_debug("logical %llu is not within any extent\n",
1320                          (unsigned long long)logical);
1321                 return -ENOENT;
1322         }
1323
1324         eb = path->nodes[0];
1325         item_size = btrfs_item_size_nr(eb, path->slots[0]);
1326         BUG_ON(item_size < sizeof(*ei));
1327
1328         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1329         flags = btrfs_extent_flags(eb, ei);
1330
1331         pr_debug("logical %llu is at position %llu within the extent (%llu "
1332                  "EXTENT_ITEM %llu) flags %#llx size %u\n",
1333                  (unsigned long long)logical,
1334                  (unsigned long long)(logical - found_key->objectid),
1335                  (unsigned long long)found_key->objectid,
1336                  (unsigned long long)found_key->offset,
1337                  (unsigned long long)flags, item_size);
1338
1339         WARN_ON(!flags_ret);
1340         if (flags_ret) {
1341                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1342                         *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1343                 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1344                         *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1345                 else
1346                         BUG_ON(1);
1347                 return 0;
1348         }
1349
1350         return -EIO;
1351 }
1352
1353 /*
1354  * helper function to iterate extent inline refs. ptr must point to a 0 value
1355  * for the first call and may be modified. it is used to track state.
1356  * if more refs exist, 0 is returned and the next call to
1357  * __get_extent_inline_ref must pass the modified ptr parameter to get the
1358  * next ref. after the last ref was processed, 1 is returned.
1359  * returns <0 on error
1360  */
1361 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1362                                 struct btrfs_extent_item *ei, u32 item_size,
1363                                 struct btrfs_extent_inline_ref **out_eiref,
1364                                 int *out_type)
1365 {
1366         unsigned long end;
1367         u64 flags;
1368         struct btrfs_tree_block_info *info;
1369
1370         if (!*ptr) {
1371                 /* first call */
1372                 flags = btrfs_extent_flags(eb, ei);
1373                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1374                         info = (struct btrfs_tree_block_info *)(ei + 1);
1375                         *out_eiref =
1376                                 (struct btrfs_extent_inline_ref *)(info + 1);
1377                 } else {
1378                         *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1379                 }
1380                 *ptr = (unsigned long)*out_eiref;
1381                 if ((void *)*ptr >= (void *)ei + item_size)
1382                         return -ENOENT;
1383         }
1384
1385         end = (unsigned long)ei + item_size;
1386         *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1387         *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1388
1389         *ptr += btrfs_extent_inline_ref_size(*out_type);
1390         WARN_ON(*ptr > end);
1391         if (*ptr == end)
1392                 return 1; /* last */
1393
1394         return 0;
1395 }
1396
1397 /*
1398  * reads the tree block backref for an extent. tree level and root are returned
1399  * through out_level and out_root. ptr must point to a 0 value for the first
1400  * call and may be modified (see __get_extent_inline_ref comment).
1401  * returns 0 if data was provided, 1 if there was no more data to provide or
1402  * <0 on error.
1403  */
1404 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1405                                 struct btrfs_extent_item *ei, u32 item_size,
1406                                 u64 *out_root, u8 *out_level)
1407 {
1408         int ret;
1409         int type;
1410         struct btrfs_tree_block_info *info;
1411         struct btrfs_extent_inline_ref *eiref;
1412
1413         if (*ptr == (unsigned long)-1)
1414                 return 1;
1415
1416         while (1) {
1417                 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1418                                                 &eiref, &type);
1419                 if (ret < 0)
1420                         return ret;
1421
1422                 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1423                     type == BTRFS_SHARED_BLOCK_REF_KEY)
1424                         break;
1425
1426                 if (ret == 1)
1427                         return 1;
1428         }
1429
1430         /* we can treat both ref types equally here */
1431         info = (struct btrfs_tree_block_info *)(ei + 1);
1432         *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1433         *out_level = btrfs_tree_block_level(eb, info);
1434
1435         if (ret == 1)
1436                 *ptr = (unsigned long)-1;
1437
1438         return 0;
1439 }
1440
1441 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1442                                 u64 root, u64 extent_item_objectid,
1443                                 iterate_extent_inodes_t *iterate, void *ctx)
1444 {
1445         struct extent_inode_elem *eie;
1446         int ret = 0;
1447
1448         for (eie = inode_list; eie; eie = eie->next) {
1449                 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1450                          "root %llu\n", extent_item_objectid,
1451                          eie->inum, eie->offset, root);
1452                 ret = iterate(eie->inum, eie->offset, root, ctx);
1453                 if (ret) {
1454                         pr_debug("stopping iteration for %llu due to ret=%d\n",
1455                                  extent_item_objectid, ret);
1456                         break;
1457                 }
1458         }
1459
1460         return ret;
1461 }
1462
1463 /*
1464  * calls iterate() for every inode that references the extent identified by
1465  * the given parameters.
1466  * when the iterator function returns a non-zero value, iteration stops.
1467  */
1468 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1469                                 u64 extent_item_objectid, u64 extent_item_pos,
1470                                 int search_commit_root,
1471                                 iterate_extent_inodes_t *iterate, void *ctx)
1472 {
1473         int ret;
1474         struct btrfs_trans_handle *trans = NULL;
1475         struct ulist *refs = NULL;
1476         struct ulist *roots = NULL;
1477         struct ulist_node *ref_node = NULL;
1478         struct ulist_node *root_node = NULL;
1479         struct seq_list tree_mod_seq_elem = {};
1480         struct ulist_iterator ref_uiter;
1481         struct ulist_iterator root_uiter;
1482
1483         pr_debug("resolving all inodes for extent %llu\n",
1484                         extent_item_objectid);
1485
1486         if (!search_commit_root) {
1487                 trans = btrfs_join_transaction(fs_info->extent_root);
1488                 if (IS_ERR(trans))
1489                         return PTR_ERR(trans);
1490                 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1491         }
1492
1493         ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1494                                    tree_mod_seq_elem.seq, &refs,
1495                                    &extent_item_pos);
1496         if (ret)
1497                 goto out;
1498
1499         ULIST_ITER_INIT(&ref_uiter);
1500         while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1501                 ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
1502                                            tree_mod_seq_elem.seq, &roots);
1503                 if (ret)
1504                         break;
1505                 ULIST_ITER_INIT(&root_uiter);
1506                 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1507                         pr_debug("root %llu references leaf %llu, data list "
1508                                  "%#llx\n", root_node->val, ref_node->val,
1509                                  (long long)ref_node->aux);
1510                         ret = iterate_leaf_refs((struct extent_inode_elem *)
1511                                                 (uintptr_t)ref_node->aux,
1512                                                 root_node->val,
1513                                                 extent_item_objectid,
1514                                                 iterate, ctx);
1515                 }
1516                 ulist_free(roots);
1517         }
1518
1519         free_leaf_list(refs);
1520 out:
1521         if (!search_commit_root) {
1522                 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1523                 btrfs_end_transaction(trans, fs_info->extent_root);
1524         }
1525
1526         return ret;
1527 }
1528
1529 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1530                                 struct btrfs_path *path,
1531                                 iterate_extent_inodes_t *iterate, void *ctx)
1532 {
1533         int ret;
1534         u64 extent_item_pos;
1535         u64 flags = 0;
1536         struct btrfs_key found_key;
1537         int search_commit_root = path->search_commit_root;
1538
1539         ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1540         btrfs_release_path(path);
1541         if (ret < 0)
1542                 return ret;
1543         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1544                 return -EINVAL;
1545
1546         extent_item_pos = logical - found_key.objectid;
1547         ret = iterate_extent_inodes(fs_info, found_key.objectid,
1548                                         extent_item_pos, search_commit_root,
1549                                         iterate, ctx);
1550
1551         return ret;
1552 }
1553
1554 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1555                               struct extent_buffer *eb, void *ctx);
1556
1557 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1558                               struct btrfs_path *path,
1559                               iterate_irefs_t *iterate, void *ctx)
1560 {
1561         int ret = 0;
1562         int slot;
1563         u32 cur;
1564         u32 len;
1565         u32 name_len;
1566         u64 parent = 0;
1567         int found = 0;
1568         struct extent_buffer *eb;
1569         struct btrfs_item *item;
1570         struct btrfs_inode_ref *iref;
1571         struct btrfs_key found_key;
1572
1573         while (!ret) {
1574                 path->leave_spinning = 1;
1575                 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1576                                      &found_key);
1577                 if (ret < 0)
1578                         break;
1579                 if (ret) {
1580                         ret = found ? 0 : -ENOENT;
1581                         break;
1582                 }
1583                 ++found;
1584
1585                 parent = found_key.offset;
1586                 slot = path->slots[0];
1587                 eb = path->nodes[0];
1588                 /* make sure we can use eb after releasing the path */
1589                 atomic_inc(&eb->refs);
1590                 btrfs_tree_read_lock(eb);
1591                 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1592                 btrfs_release_path(path);
1593
1594                 item = btrfs_item_nr(eb, slot);
1595                 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1596
1597                 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1598                         name_len = btrfs_inode_ref_name_len(eb, iref);
1599                         /* path must be released before calling iterate()! */
1600                         pr_debug("following ref at offset %u for inode %llu in "
1601                                  "tree %llu\n", cur,
1602                                  (unsigned long long)found_key.objectid,
1603                                  (unsigned long long)fs_root->objectid);
1604                         ret = iterate(parent, name_len,
1605                                       (unsigned long)(iref + 1), eb, ctx);
1606                         if (ret)
1607                                 break;
1608                         len = sizeof(*iref) + name_len;
1609                         iref = (struct btrfs_inode_ref *)((char *)iref + len);
1610                 }
1611                 btrfs_tree_read_unlock_blocking(eb);
1612                 free_extent_buffer(eb);
1613         }
1614
1615         btrfs_release_path(path);
1616
1617         return ret;
1618 }
1619
1620 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1621                                  struct btrfs_path *path,
1622                                  iterate_irefs_t *iterate, void *ctx)
1623 {
1624         int ret;
1625         int slot;
1626         u64 offset = 0;
1627         u64 parent;
1628         int found = 0;
1629         struct extent_buffer *eb;
1630         struct btrfs_inode_extref *extref;
1631         struct extent_buffer *leaf;
1632         u32 item_size;
1633         u32 cur_offset;
1634         unsigned long ptr;
1635
1636         while (1) {
1637                 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1638                                             &offset);
1639                 if (ret < 0)
1640                         break;
1641                 if (ret) {
1642                         ret = found ? 0 : -ENOENT;
1643                         break;
1644                 }
1645                 ++found;
1646
1647                 slot = path->slots[0];
1648                 eb = path->nodes[0];
1649                 /* make sure we can use eb after releasing the path */
1650                 atomic_inc(&eb->refs);
1651
1652                 btrfs_tree_read_lock(eb);
1653                 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1654                 btrfs_release_path(path);
1655
1656                 leaf = path->nodes[0];
1657                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1658                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1659                 cur_offset = 0;
1660
1661                 while (cur_offset < item_size) {
1662                         u32 name_len;
1663
1664                         extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1665                         parent = btrfs_inode_extref_parent(eb, extref);
1666                         name_len = btrfs_inode_extref_name_len(eb, extref);
1667                         ret = iterate(parent, name_len,
1668                                       (unsigned long)&extref->name, eb, ctx);
1669                         if (ret)
1670                                 break;
1671
1672                         cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1673                         cur_offset += sizeof(*extref);
1674                 }
1675                 btrfs_tree_read_unlock_blocking(eb);
1676                 free_extent_buffer(eb);
1677
1678                 offset++;
1679         }
1680
1681         btrfs_release_path(path);
1682
1683         return ret;
1684 }
1685
1686 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1687                          struct btrfs_path *path, iterate_irefs_t *iterate,
1688                          void *ctx)
1689 {
1690         int ret;
1691         int found_refs = 0;
1692
1693         ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1694         if (!ret)
1695                 ++found_refs;
1696         else if (ret != -ENOENT)
1697                 return ret;
1698
1699         ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1700         if (ret == -ENOENT && found_refs)
1701                 return 0;
1702
1703         return ret;
1704 }
1705
1706 /*
1707  * returns 0 if the path could be dumped (probably truncated)
1708  * returns <0 in case of an error
1709  */
1710 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1711                          struct extent_buffer *eb, void *ctx)
1712 {
1713         struct inode_fs_paths *ipath = ctx;
1714         char *fspath;
1715         char *fspath_min;
1716         int i = ipath->fspath->elem_cnt;
1717         const int s_ptr = sizeof(char *);
1718         u32 bytes_left;
1719
1720         bytes_left = ipath->fspath->bytes_left > s_ptr ?
1721                                         ipath->fspath->bytes_left - s_ptr : 0;
1722
1723         fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1724         fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1725                                    name_off, eb, inum, fspath_min, bytes_left);
1726         if (IS_ERR(fspath))
1727                 return PTR_ERR(fspath);
1728
1729         if (fspath > fspath_min) {
1730                 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1731                 ++ipath->fspath->elem_cnt;
1732                 ipath->fspath->bytes_left = fspath - fspath_min;
1733         } else {
1734                 ++ipath->fspath->elem_missed;
1735                 ipath->fspath->bytes_missing += fspath_min - fspath;
1736                 ipath->fspath->bytes_left = 0;
1737         }
1738
1739         return 0;
1740 }
1741
1742 /*
1743  * this dumps all file system paths to the inode into the ipath struct, provided
1744  * is has been created large enough. each path is zero-terminated and accessed
1745  * from ipath->fspath->val[i].
1746  * when it returns, there are ipath->fspath->elem_cnt number of paths available
1747  * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1748  * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1749  * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1750  * have been needed to return all paths.
1751  */
1752 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1753 {
1754         return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1755                              inode_to_path, ipath);
1756 }
1757
1758 struct btrfs_data_container *init_data_container(u32 total_bytes)
1759 {
1760         struct btrfs_data_container *data;
1761         size_t alloc_bytes;
1762
1763         alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1764         data = vmalloc(alloc_bytes);
1765         if (!data)
1766                 return ERR_PTR(-ENOMEM);
1767
1768         if (total_bytes >= sizeof(*data)) {
1769                 data->bytes_left = total_bytes - sizeof(*data);
1770                 data->bytes_missing = 0;
1771         } else {
1772                 data->bytes_missing = sizeof(*data) - total_bytes;
1773                 data->bytes_left = 0;
1774         }
1775
1776         data->elem_cnt = 0;
1777         data->elem_missed = 0;
1778
1779         return data;
1780 }
1781
1782 /*
1783  * allocates space to return multiple file system paths for an inode.
1784  * total_bytes to allocate are passed, note that space usable for actual path
1785  * information will be total_bytes - sizeof(struct inode_fs_paths).
1786  * the returned pointer must be freed with free_ipath() in the end.
1787  */
1788 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1789                                         struct btrfs_path *path)
1790 {
1791         struct inode_fs_paths *ifp;
1792         struct btrfs_data_container *fspath;
1793
1794         fspath = init_data_container(total_bytes);
1795         if (IS_ERR(fspath))
1796                 return (void *)fspath;
1797
1798         ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1799         if (!ifp) {
1800                 kfree(fspath);
1801                 return ERR_PTR(-ENOMEM);
1802         }
1803
1804         ifp->btrfs_path = path;
1805         ifp->fspath = fspath;
1806         ifp->fs_root = fs_root;
1807
1808         return ifp;
1809 }
1810
1811 void free_ipath(struct inode_fs_paths *ipath)
1812 {
1813         if (!ipath)
1814                 return;
1815         vfree(ipath->fspath);
1816         kfree(ipath);
1817 }