Btrfs: Fix balance panic
[linux-2.6.git] / fs / btrfs / relocation.c
1 /*
2  * Copyright (C) 2009 Oracle.  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/sched.h>
20 #include <linux/pagemap.h>
21 #include <linux/writeback.h>
22 #include <linux/blkdev.h>
23 #include <linux/rbtree.h>
24 #include <linux/slab.h>
25 #include "ctree.h"
26 #include "disk-io.h"
27 #include "transaction.h"
28 #include "volumes.h"
29 #include "locking.h"
30 #include "btrfs_inode.h"
31 #include "async-thread.h"
32 #include "free-space-cache.h"
33
34 /*
35  * backref_node, mapping_node and tree_block start with this
36  */
37 struct tree_entry {
38         struct rb_node rb_node;
39         u64 bytenr;
40 };
41
42 /*
43  * present a tree block in the backref cache
44  */
45 struct backref_node {
46         struct rb_node rb_node;
47         u64 bytenr;
48
49         u64 new_bytenr;
50         /* objectid of tree block owner, can be not uptodate */
51         u64 owner;
52         /* link to pending, changed or detached list */
53         struct list_head list;
54         /* list of upper level blocks reference this block */
55         struct list_head upper;
56         /* list of child blocks in the cache */
57         struct list_head lower;
58         /* NULL if this node is not tree root */
59         struct btrfs_root *root;
60         /* extent buffer got by COW the block */
61         struct extent_buffer *eb;
62         /* level of tree block */
63         unsigned int level:8;
64         /* is the block in non-reference counted tree */
65         unsigned int cowonly:1;
66         /* 1 if no child node in the cache */
67         unsigned int lowest:1;
68         /* is the extent buffer locked */
69         unsigned int locked:1;
70         /* has the block been processed */
71         unsigned int processed:1;
72         /* have backrefs of this block been checked */
73         unsigned int checked:1;
74         /*
75          * 1 if corresponding block has been cowed but some upper
76          * level block pointers may not point to the new location
77          */
78         unsigned int pending:1;
79         /*
80          * 1 if the backref node isn't connected to any other
81          * backref node.
82          */
83         unsigned int detached:1;
84 };
85
86 /*
87  * present a block pointer in the backref cache
88  */
89 struct backref_edge {
90         struct list_head list[2];
91         struct backref_node *node[2];
92 };
93
94 #define LOWER   0
95 #define UPPER   1
96
97 struct backref_cache {
98         /* red black tree of all backref nodes in the cache */
99         struct rb_root rb_root;
100         /* for passing backref nodes to btrfs_reloc_cow_block */
101         struct backref_node *path[BTRFS_MAX_LEVEL];
102         /*
103          * list of blocks that have been cowed but some block
104          * pointers in upper level blocks may not reflect the
105          * new location
106          */
107         struct list_head pending[BTRFS_MAX_LEVEL];
108         /* list of backref nodes with no child node */
109         struct list_head leaves;
110         /* list of blocks that have been cowed in current transaction */
111         struct list_head changed;
112         /* list of detached backref node. */
113         struct list_head detached;
114
115         u64 last_trans;
116
117         int nr_nodes;
118         int nr_edges;
119 };
120
121 /*
122  * map address of tree root to tree
123  */
124 struct mapping_node {
125         struct rb_node rb_node;
126         u64 bytenr;
127         void *data;
128 };
129
130 struct mapping_tree {
131         struct rb_root rb_root;
132         spinlock_t lock;
133 };
134
135 /*
136  * present a tree block to process
137  */
138 struct tree_block {
139         struct rb_node rb_node;
140         u64 bytenr;
141         struct btrfs_key key;
142         unsigned int level:8;
143         unsigned int key_ready:1;
144 };
145
146 #define MAX_EXTENTS 128
147
148 struct file_extent_cluster {
149         u64 start;
150         u64 end;
151         u64 boundary[MAX_EXTENTS];
152         unsigned int nr;
153 };
154
155 struct reloc_control {
156         /* block group to relocate */
157         struct btrfs_block_group_cache *block_group;
158         /* extent tree */
159         struct btrfs_root *extent_root;
160         /* inode for moving data */
161         struct inode *data_inode;
162
163         struct btrfs_block_rsv *block_rsv;
164
165         struct backref_cache backref_cache;
166
167         struct file_extent_cluster cluster;
168         /* tree blocks have been processed */
169         struct extent_io_tree processed_blocks;
170         /* map start of tree root to corresponding reloc tree */
171         struct mapping_tree reloc_root_tree;
172         /* list of reloc trees */
173         struct list_head reloc_roots;
174         /* size of metadata reservation for merging reloc trees */
175         u64 merging_rsv_size;
176         /* size of relocated tree nodes */
177         u64 nodes_relocated;
178
179         u64 search_start;
180         u64 extents_found;
181
182         unsigned int stage:8;
183         unsigned int create_reloc_tree:1;
184         unsigned int merge_reloc_tree:1;
185         unsigned int found_file_extent:1;
186         unsigned int commit_transaction:1;
187 };
188
189 /* stages of data relocation */
190 #define MOVE_DATA_EXTENTS       0
191 #define UPDATE_DATA_PTRS        1
192
193 static void remove_backref_node(struct backref_cache *cache,
194                                 struct backref_node *node);
195 static void __mark_block_processed(struct reloc_control *rc,
196                                    struct backref_node *node);
197
198 static void mapping_tree_init(struct mapping_tree *tree)
199 {
200         tree->rb_root = RB_ROOT;
201         spin_lock_init(&tree->lock);
202 }
203
204 static void backref_cache_init(struct backref_cache *cache)
205 {
206         int i;
207         cache->rb_root = RB_ROOT;
208         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
209                 INIT_LIST_HEAD(&cache->pending[i]);
210         INIT_LIST_HEAD(&cache->changed);
211         INIT_LIST_HEAD(&cache->detached);
212         INIT_LIST_HEAD(&cache->leaves);
213 }
214
215 static void backref_cache_cleanup(struct backref_cache *cache)
216 {
217         struct backref_node *node;
218         int i;
219
220         while (!list_empty(&cache->detached)) {
221                 node = list_entry(cache->detached.next,
222                                   struct backref_node, list);
223                 remove_backref_node(cache, node);
224         }
225
226         while (!list_empty(&cache->leaves)) {
227                 node = list_entry(cache->leaves.next,
228                                   struct backref_node, lower);
229                 remove_backref_node(cache, node);
230         }
231
232         cache->last_trans = 0;
233
234         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
235                 BUG_ON(!list_empty(&cache->pending[i]));
236         BUG_ON(!list_empty(&cache->changed));
237         BUG_ON(!list_empty(&cache->detached));
238         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
239         BUG_ON(cache->nr_nodes);
240         BUG_ON(cache->nr_edges);
241 }
242
243 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
244 {
245         struct backref_node *node;
246
247         node = kzalloc(sizeof(*node), GFP_NOFS);
248         if (node) {
249                 INIT_LIST_HEAD(&node->list);
250                 INIT_LIST_HEAD(&node->upper);
251                 INIT_LIST_HEAD(&node->lower);
252                 RB_CLEAR_NODE(&node->rb_node);
253                 cache->nr_nodes++;
254         }
255         return node;
256 }
257
258 static void free_backref_node(struct backref_cache *cache,
259                               struct backref_node *node)
260 {
261         if (node) {
262                 cache->nr_nodes--;
263                 kfree(node);
264         }
265 }
266
267 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
268 {
269         struct backref_edge *edge;
270
271         edge = kzalloc(sizeof(*edge), GFP_NOFS);
272         if (edge)
273                 cache->nr_edges++;
274         return edge;
275 }
276
277 static void free_backref_edge(struct backref_cache *cache,
278                               struct backref_edge *edge)
279 {
280         if (edge) {
281                 cache->nr_edges--;
282                 kfree(edge);
283         }
284 }
285
286 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
287                                    struct rb_node *node)
288 {
289         struct rb_node **p = &root->rb_node;
290         struct rb_node *parent = NULL;
291         struct tree_entry *entry;
292
293         while (*p) {
294                 parent = *p;
295                 entry = rb_entry(parent, struct tree_entry, rb_node);
296
297                 if (bytenr < entry->bytenr)
298                         p = &(*p)->rb_left;
299                 else if (bytenr > entry->bytenr)
300                         p = &(*p)->rb_right;
301                 else
302                         return parent;
303         }
304
305         rb_link_node(node, parent, p);
306         rb_insert_color(node, root);
307         return NULL;
308 }
309
310 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
311 {
312         struct rb_node *n = root->rb_node;
313         struct tree_entry *entry;
314
315         while (n) {
316                 entry = rb_entry(n, struct tree_entry, rb_node);
317
318                 if (bytenr < entry->bytenr)
319                         n = n->rb_left;
320                 else if (bytenr > entry->bytenr)
321                         n = n->rb_right;
322                 else
323                         return n;
324         }
325         return NULL;
326 }
327
328 /*
329  * walk up backref nodes until reach node presents tree root
330  */
331 static struct backref_node *walk_up_backref(struct backref_node *node,
332                                             struct backref_edge *edges[],
333                                             int *index)
334 {
335         struct backref_edge *edge;
336         int idx = *index;
337
338         while (!list_empty(&node->upper)) {
339                 edge = list_entry(node->upper.next,
340                                   struct backref_edge, list[LOWER]);
341                 edges[idx++] = edge;
342                 node = edge->node[UPPER];
343         }
344         BUG_ON(node->detached);
345         *index = idx;
346         return node;
347 }
348
349 /*
350  * walk down backref nodes to find start of next reference path
351  */
352 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
353                                               int *index)
354 {
355         struct backref_edge *edge;
356         struct backref_node *lower;
357         int idx = *index;
358
359         while (idx > 0) {
360                 edge = edges[idx - 1];
361                 lower = edge->node[LOWER];
362                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
363                         idx--;
364                         continue;
365                 }
366                 edge = list_entry(edge->list[LOWER].next,
367                                   struct backref_edge, list[LOWER]);
368                 edges[idx - 1] = edge;
369                 *index = idx;
370                 return edge->node[UPPER];
371         }
372         *index = 0;
373         return NULL;
374 }
375
376 static void unlock_node_buffer(struct backref_node *node)
377 {
378         if (node->locked) {
379                 btrfs_tree_unlock(node->eb);
380                 node->locked = 0;
381         }
382 }
383
384 static void drop_node_buffer(struct backref_node *node)
385 {
386         if (node->eb) {
387                 unlock_node_buffer(node);
388                 free_extent_buffer(node->eb);
389                 node->eb = NULL;
390         }
391 }
392
393 static void drop_backref_node(struct backref_cache *tree,
394                               struct backref_node *node)
395 {
396         BUG_ON(!list_empty(&node->upper));
397
398         drop_node_buffer(node);
399         list_del(&node->list);
400         list_del(&node->lower);
401         if (!RB_EMPTY_NODE(&node->rb_node))
402                 rb_erase(&node->rb_node, &tree->rb_root);
403         free_backref_node(tree, node);
404 }
405
406 /*
407  * remove a backref node from the backref cache
408  */
409 static void remove_backref_node(struct backref_cache *cache,
410                                 struct backref_node *node)
411 {
412         struct backref_node *upper;
413         struct backref_edge *edge;
414
415         if (!node)
416                 return;
417
418         BUG_ON(!node->lowest && !node->detached);
419         while (!list_empty(&node->upper)) {
420                 edge = list_entry(node->upper.next, struct backref_edge,
421                                   list[LOWER]);
422                 upper = edge->node[UPPER];
423                 list_del(&edge->list[LOWER]);
424                 list_del(&edge->list[UPPER]);
425                 free_backref_edge(cache, edge);
426
427                 if (RB_EMPTY_NODE(&upper->rb_node)) {
428                         BUG_ON(!list_empty(&node->upper));
429                         drop_backref_node(cache, node);
430                         node = upper;
431                         node->lowest = 1;
432                         continue;
433                 }
434                 /*
435                  * add the node to leaf node list if no other
436                  * child block cached.
437                  */
438                 if (list_empty(&upper->lower)) {
439                         list_add_tail(&upper->lower, &cache->leaves);
440                         upper->lowest = 1;
441                 }
442         }
443
444         drop_backref_node(cache, node);
445 }
446
447 static void update_backref_node(struct backref_cache *cache,
448                                 struct backref_node *node, u64 bytenr)
449 {
450         struct rb_node *rb_node;
451         rb_erase(&node->rb_node, &cache->rb_root);
452         node->bytenr = bytenr;
453         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
454         BUG_ON(rb_node);
455 }
456
457 /*
458  * update backref cache after a transaction commit
459  */
460 static int update_backref_cache(struct btrfs_trans_handle *trans,
461                                 struct backref_cache *cache)
462 {
463         struct backref_node *node;
464         int level = 0;
465
466         if (cache->last_trans == 0) {
467                 cache->last_trans = trans->transid;
468                 return 0;
469         }
470
471         if (cache->last_trans == trans->transid)
472                 return 0;
473
474         /*
475          * detached nodes are used to avoid unnecessary backref
476          * lookup. transaction commit changes the extent tree.
477          * so the detached nodes are no longer useful.
478          */
479         while (!list_empty(&cache->detached)) {
480                 node = list_entry(cache->detached.next,
481                                   struct backref_node, list);
482                 remove_backref_node(cache, node);
483         }
484
485         while (!list_empty(&cache->changed)) {
486                 node = list_entry(cache->changed.next,
487                                   struct backref_node, list);
488                 list_del_init(&node->list);
489                 BUG_ON(node->pending);
490                 update_backref_node(cache, node, node->new_bytenr);
491         }
492
493         /*
494          * some nodes can be left in the pending list if there were
495          * errors during processing the pending nodes.
496          */
497         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
498                 list_for_each_entry(node, &cache->pending[level], list) {
499                         BUG_ON(!node->pending);
500                         if (node->bytenr == node->new_bytenr)
501                                 continue;
502                         update_backref_node(cache, node, node->new_bytenr);
503                 }
504         }
505
506         cache->last_trans = 0;
507         return 1;
508 }
509
510 static int should_ignore_root(struct btrfs_root *root)
511 {
512         struct btrfs_root *reloc_root;
513
514         if (!root->ref_cows)
515                 return 0;
516
517         reloc_root = root->reloc_root;
518         if (!reloc_root)
519                 return 0;
520
521         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
522             root->fs_info->running_transaction->transid - 1)
523                 return 0;
524         /*
525          * if there is reloc tree and it was created in previous
526          * transaction backref lookup can find the reloc tree,
527          * so backref node for the fs tree root is useless for
528          * relocation.
529          */
530         return 1;
531 }
532
533 /*
534  * find reloc tree by address of tree root
535  */
536 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
537                                           u64 bytenr)
538 {
539         struct rb_node *rb_node;
540         struct mapping_node *node;
541         struct btrfs_root *root = NULL;
542
543         spin_lock(&rc->reloc_root_tree.lock);
544         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
545         if (rb_node) {
546                 node = rb_entry(rb_node, struct mapping_node, rb_node);
547                 root = (struct btrfs_root *)node->data;
548         }
549         spin_unlock(&rc->reloc_root_tree.lock);
550         return root;
551 }
552
553 static int is_cowonly_root(u64 root_objectid)
554 {
555         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
556             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
557             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
558             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
559             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
560             root_objectid == BTRFS_CSUM_TREE_OBJECTID)
561                 return 1;
562         return 0;
563 }
564
565 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
566                                         u64 root_objectid)
567 {
568         struct btrfs_key key;
569
570         key.objectid = root_objectid;
571         key.type = BTRFS_ROOT_ITEM_KEY;
572         if (is_cowonly_root(root_objectid))
573                 key.offset = 0;
574         else
575                 key.offset = (u64)-1;
576
577         return btrfs_read_fs_root_no_name(fs_info, &key);
578 }
579
580 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
581 static noinline_for_stack
582 struct btrfs_root *find_tree_root(struct reloc_control *rc,
583                                   struct extent_buffer *leaf,
584                                   struct btrfs_extent_ref_v0 *ref0)
585 {
586         struct btrfs_root *root;
587         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
588         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
589
590         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
591
592         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
593         BUG_ON(IS_ERR(root));
594
595         if (root->ref_cows &&
596             generation != btrfs_root_generation(&root->root_item))
597                 return NULL;
598
599         return root;
600 }
601 #endif
602
603 static noinline_for_stack
604 int find_inline_backref(struct extent_buffer *leaf, int slot,
605                         unsigned long *ptr, unsigned long *end)
606 {
607         struct btrfs_extent_item *ei;
608         struct btrfs_tree_block_info *bi;
609         u32 item_size;
610
611         item_size = btrfs_item_size_nr(leaf, slot);
612 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
613         if (item_size < sizeof(*ei)) {
614                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
615                 return 1;
616         }
617 #endif
618         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
619         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
620                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
621
622         if (item_size <= sizeof(*ei) + sizeof(*bi)) {
623                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
624                 return 1;
625         }
626
627         bi = (struct btrfs_tree_block_info *)(ei + 1);
628         *ptr = (unsigned long)(bi + 1);
629         *end = (unsigned long)ei + item_size;
630         return 0;
631 }
632
633 /*
634  * build backref tree for a given tree block. root of the backref tree
635  * corresponds the tree block, leaves of the backref tree correspond
636  * roots of b-trees that reference the tree block.
637  *
638  * the basic idea of this function is check backrefs of a given block
639  * to find upper level blocks that refernece the block, and then check
640  * bakcrefs of these upper level blocks recursively. the recursion stop
641  * when tree root is reached or backrefs for the block is cached.
642  *
643  * NOTE: if we find backrefs for a block are cached, we know backrefs
644  * for all upper level blocks that directly/indirectly reference the
645  * block are also cached.
646  */
647 static noinline_for_stack
648 struct backref_node *build_backref_tree(struct reloc_control *rc,
649                                         struct btrfs_key *node_key,
650                                         int level, u64 bytenr)
651 {
652         struct backref_cache *cache = &rc->backref_cache;
653         struct btrfs_path *path1;
654         struct btrfs_path *path2;
655         struct extent_buffer *eb;
656         struct btrfs_root *root;
657         struct backref_node *cur;
658         struct backref_node *upper;
659         struct backref_node *lower;
660         struct backref_node *node = NULL;
661         struct backref_node *exist = NULL;
662         struct backref_edge *edge;
663         struct rb_node *rb_node;
664         struct btrfs_key key;
665         unsigned long end;
666         unsigned long ptr;
667         LIST_HEAD(list);
668         LIST_HEAD(useless);
669         int cowonly;
670         int ret;
671         int err = 0;
672
673         path1 = btrfs_alloc_path();
674         path2 = btrfs_alloc_path();
675         if (!path1 || !path2) {
676                 err = -ENOMEM;
677                 goto out;
678         }
679
680         node = alloc_backref_node(cache);
681         if (!node) {
682                 err = -ENOMEM;
683                 goto out;
684         }
685
686         node->bytenr = bytenr;
687         node->level = level;
688         node->lowest = 1;
689         cur = node;
690 again:
691         end = 0;
692         ptr = 0;
693         key.objectid = cur->bytenr;
694         key.type = BTRFS_EXTENT_ITEM_KEY;
695         key.offset = (u64)-1;
696
697         path1->search_commit_root = 1;
698         path1->skip_locking = 1;
699         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
700                                 0, 0);
701         if (ret < 0) {
702                 err = ret;
703                 goto out;
704         }
705         BUG_ON(!ret || !path1->slots[0]);
706
707         path1->slots[0]--;
708
709         WARN_ON(cur->checked);
710         if (!list_empty(&cur->upper)) {
711                 /*
712                  * the backref was added previously when processsing
713                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
714                  */
715                 BUG_ON(!list_is_singular(&cur->upper));
716                 edge = list_entry(cur->upper.next, struct backref_edge,
717                                   list[LOWER]);
718                 BUG_ON(!list_empty(&edge->list[UPPER]));
719                 exist = edge->node[UPPER];
720                 /*
721                  * add the upper level block to pending list if we need
722                  * check its backrefs
723                  */
724                 if (!exist->checked)
725                         list_add_tail(&edge->list[UPPER], &list);
726         } else {
727                 exist = NULL;
728         }
729
730         while (1) {
731                 cond_resched();
732                 eb = path1->nodes[0];
733
734                 if (ptr >= end) {
735                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
736                                 ret = btrfs_next_leaf(rc->extent_root, path1);
737                                 if (ret < 0) {
738                                         err = ret;
739                                         goto out;
740                                 }
741                                 if (ret > 0)
742                                         break;
743                                 eb = path1->nodes[0];
744                         }
745
746                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
747                         if (key.objectid != cur->bytenr) {
748                                 WARN_ON(exist);
749                                 break;
750                         }
751
752                         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
753                                 ret = find_inline_backref(eb, path1->slots[0],
754                                                           &ptr, &end);
755                                 if (ret)
756                                         goto next;
757                         }
758                 }
759
760                 if (ptr < end) {
761                         /* update key for inline back ref */
762                         struct btrfs_extent_inline_ref *iref;
763                         iref = (struct btrfs_extent_inline_ref *)ptr;
764                         key.type = btrfs_extent_inline_ref_type(eb, iref);
765                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
766                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
767                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
768                 }
769
770                 if (exist &&
771                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
772                       exist->owner == key.offset) ||
773                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
774                       exist->bytenr == key.offset))) {
775                         exist = NULL;
776                         goto next;
777                 }
778
779 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
780                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
781                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
782                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
783                                 struct btrfs_extent_ref_v0 *ref0;
784                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
785                                                 struct btrfs_extent_ref_v0);
786                                 if (key.objectid == key.offset) {
787                                         root = find_tree_root(rc, eb, ref0);
788                                         if (root && !should_ignore_root(root))
789                                                 cur->root = root;
790                                         else
791                                                 list_add(&cur->list, &useless);
792                                         break;
793                                 }
794                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
795                                                                       ref0)))
796                                         cur->cowonly = 1;
797                         }
798 #else
799                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
800                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
801 #endif
802                         if (key.objectid == key.offset) {
803                                 /*
804                                  * only root blocks of reloc trees use
805                                  * backref of this type.
806                                  */
807                                 root = find_reloc_root(rc, cur->bytenr);
808                                 BUG_ON(!root);
809                                 cur->root = root;
810                                 break;
811                         }
812
813                         edge = alloc_backref_edge(cache);
814                         if (!edge) {
815                                 err = -ENOMEM;
816                                 goto out;
817                         }
818                         rb_node = tree_search(&cache->rb_root, key.offset);
819                         if (!rb_node) {
820                                 upper = alloc_backref_node(cache);
821                                 if (!upper) {
822                                         free_backref_edge(cache, edge);
823                                         err = -ENOMEM;
824                                         goto out;
825                                 }
826                                 upper->bytenr = key.offset;
827                                 upper->level = cur->level + 1;
828                                 /*
829                                  *  backrefs for the upper level block isn't
830                                  *  cached, add the block to pending list
831                                  */
832                                 list_add_tail(&edge->list[UPPER], &list);
833                         } else {
834                                 upper = rb_entry(rb_node, struct backref_node,
835                                                  rb_node);
836                                 BUG_ON(!upper->checked);
837                                 INIT_LIST_HEAD(&edge->list[UPPER]);
838                         }
839                         list_add_tail(&edge->list[LOWER], &cur->upper);
840                         edge->node[LOWER] = cur;
841                         edge->node[UPPER] = upper;
842
843                         goto next;
844                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
845                         goto next;
846                 }
847
848                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
849                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
850                 if (IS_ERR(root)) {
851                         err = PTR_ERR(root);
852                         goto out;
853                 }
854
855                 if (!root->ref_cows)
856                         cur->cowonly = 1;
857
858                 if (btrfs_root_level(&root->root_item) == cur->level) {
859                         /* tree root */
860                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
861                                cur->bytenr);
862                         if (should_ignore_root(root))
863                                 list_add(&cur->list, &useless);
864                         else
865                                 cur->root = root;
866                         break;
867                 }
868
869                 level = cur->level + 1;
870
871                 /*
872                  * searching the tree to find upper level blocks
873                  * reference the block.
874                  */
875                 path2->search_commit_root = 1;
876                 path2->skip_locking = 1;
877                 path2->lowest_level = level;
878                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
879                 path2->lowest_level = 0;
880                 if (ret < 0) {
881                         err = ret;
882                         goto out;
883                 }
884                 if (ret > 0 && path2->slots[level] > 0)
885                         path2->slots[level]--;
886
887                 eb = path2->nodes[level];
888                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
889                         cur->bytenr);
890
891                 lower = cur;
892                 for (; level < BTRFS_MAX_LEVEL; level++) {
893                         if (!path2->nodes[level]) {
894                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
895                                        lower->bytenr);
896                                 if (should_ignore_root(root))
897                                         list_add(&lower->list, &useless);
898                                 else
899                                         lower->root = root;
900                                 break;
901                         }
902
903                         edge = alloc_backref_edge(cache);
904                         if (!edge) {
905                                 err = -ENOMEM;
906                                 goto out;
907                         }
908
909                         eb = path2->nodes[level];
910                         rb_node = tree_search(&cache->rb_root, eb->start);
911                         if (!rb_node) {
912                                 upper = alloc_backref_node(cache);
913                                 if (!upper) {
914                                         free_backref_edge(cache, edge);
915                                         err = -ENOMEM;
916                                         goto out;
917                                 }
918                                 upper->bytenr = eb->start;
919                                 upper->owner = btrfs_header_owner(eb);
920                                 upper->level = lower->level + 1;
921                                 if (!root->ref_cows)
922                                         upper->cowonly = 1;
923
924                                 /*
925                                  * if we know the block isn't shared
926                                  * we can void checking its backrefs.
927                                  */
928                                 if (btrfs_block_can_be_shared(root, eb))
929                                         upper->checked = 0;
930                                 else
931                                         upper->checked = 1;
932
933                                 /*
934                                  * add the block to pending list if we
935                                  * need check its backrefs. only block
936                                  * at 'cur->level + 1' is added to the
937                                  * tail of pending list. this guarantees
938                                  * we check backrefs from lower level
939                                  * blocks to upper level blocks.
940                                  */
941                                 if (!upper->checked &&
942                                     level == cur->level + 1) {
943                                         list_add_tail(&edge->list[UPPER],
944                                                       &list);
945                                 } else
946                                         INIT_LIST_HEAD(&edge->list[UPPER]);
947                         } else {
948                                 upper = rb_entry(rb_node, struct backref_node,
949                                                  rb_node);
950                                 BUG_ON(!upper->checked);
951                                 INIT_LIST_HEAD(&edge->list[UPPER]);
952                                 if (!upper->owner)
953                                         upper->owner = btrfs_header_owner(eb);
954                         }
955                         list_add_tail(&edge->list[LOWER], &lower->upper);
956                         edge->node[LOWER] = lower;
957                         edge->node[UPPER] = upper;
958
959                         if (rb_node)
960                                 break;
961                         lower = upper;
962                         upper = NULL;
963                 }
964                 btrfs_release_path(root, path2);
965 next:
966                 if (ptr < end) {
967                         ptr += btrfs_extent_inline_ref_size(key.type);
968                         if (ptr >= end) {
969                                 WARN_ON(ptr > end);
970                                 ptr = 0;
971                                 end = 0;
972                         }
973                 }
974                 if (ptr >= end)
975                         path1->slots[0]++;
976         }
977         btrfs_release_path(rc->extent_root, path1);
978
979         cur->checked = 1;
980         WARN_ON(exist);
981
982         /* the pending list isn't empty, take the first block to process */
983         if (!list_empty(&list)) {
984                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
985                 list_del_init(&edge->list[UPPER]);
986                 cur = edge->node[UPPER];
987                 goto again;
988         }
989
990         /*
991          * everything goes well, connect backref nodes and insert backref nodes
992          * into the cache.
993          */
994         BUG_ON(!node->checked);
995         cowonly = node->cowonly;
996         if (!cowonly) {
997                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
998                                       &node->rb_node);
999                 BUG_ON(rb_node);
1000                 list_add_tail(&node->lower, &cache->leaves);
1001         }
1002
1003         list_for_each_entry(edge, &node->upper, list[LOWER])
1004                 list_add_tail(&edge->list[UPPER], &list);
1005
1006         while (!list_empty(&list)) {
1007                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1008                 list_del_init(&edge->list[UPPER]);
1009                 upper = edge->node[UPPER];
1010                 if (upper->detached) {
1011                         list_del(&edge->list[LOWER]);
1012                         lower = edge->node[LOWER];
1013                         free_backref_edge(cache, edge);
1014                         if (list_empty(&lower->upper))
1015                                 list_add(&lower->list, &useless);
1016                         continue;
1017                 }
1018
1019                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1020                         if (upper->lowest) {
1021                                 list_del_init(&upper->lower);
1022                                 upper->lowest = 0;
1023                         }
1024
1025                         list_add_tail(&edge->list[UPPER], &upper->lower);
1026                         continue;
1027                 }
1028
1029                 BUG_ON(!upper->checked);
1030                 BUG_ON(cowonly != upper->cowonly);
1031                 if (!cowonly) {
1032                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1033                                               &upper->rb_node);
1034                         BUG_ON(rb_node);
1035                 }
1036
1037                 list_add_tail(&edge->list[UPPER], &upper->lower);
1038
1039                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1040                         list_add_tail(&edge->list[UPPER], &list);
1041         }
1042         /*
1043          * process useless backref nodes. backref nodes for tree leaves
1044          * are deleted from the cache. backref nodes for upper level
1045          * tree blocks are left in the cache to avoid unnecessary backref
1046          * lookup.
1047          */
1048         while (!list_empty(&useless)) {
1049                 upper = list_entry(useless.next, struct backref_node, list);
1050                 list_del_init(&upper->list);
1051                 BUG_ON(!list_empty(&upper->upper));
1052                 if (upper == node)
1053                         node = NULL;
1054                 if (upper->lowest) {
1055                         list_del_init(&upper->lower);
1056                         upper->lowest = 0;
1057                 }
1058                 while (!list_empty(&upper->lower)) {
1059                         edge = list_entry(upper->lower.next,
1060                                           struct backref_edge, list[UPPER]);
1061                         list_del(&edge->list[UPPER]);
1062                         list_del(&edge->list[LOWER]);
1063                         lower = edge->node[LOWER];
1064                         free_backref_edge(cache, edge);
1065
1066                         if (list_empty(&lower->upper))
1067                                 list_add(&lower->list, &useless);
1068                 }
1069                 __mark_block_processed(rc, upper);
1070                 if (upper->level > 0) {
1071                         list_add(&upper->list, &cache->detached);
1072                         upper->detached = 1;
1073                 } else {
1074                         rb_erase(&upper->rb_node, &cache->rb_root);
1075                         free_backref_node(cache, upper);
1076                 }
1077         }
1078 out:
1079         btrfs_free_path(path1);
1080         btrfs_free_path(path2);
1081         if (err) {
1082                 while (!list_empty(&useless)) {
1083                         lower = list_entry(useless.next,
1084                                            struct backref_node, upper);
1085                         list_del_init(&lower->upper);
1086                 }
1087                 upper = node;
1088                 INIT_LIST_HEAD(&list);
1089                 while (upper) {
1090                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1091                                 list_splice_tail(&upper->upper, &list);
1092                                 free_backref_node(cache, upper);
1093                         }
1094
1095                         if (list_empty(&list))
1096                                 break;
1097
1098                         edge = list_entry(list.next, struct backref_edge,
1099                                           list[LOWER]);
1100                         list_del(&edge->list[LOWER]);
1101                         upper = edge->node[UPPER];
1102                         free_backref_edge(cache, edge);
1103                 }
1104                 return ERR_PTR(err);
1105         }
1106         BUG_ON(node && node->detached);
1107         return node;
1108 }
1109
1110 /*
1111  * helper to add backref node for the newly created snapshot.
1112  * the backref node is created by cloning backref node that
1113  * corresponds to root of source tree
1114  */
1115 static int clone_backref_node(struct btrfs_trans_handle *trans,
1116                               struct reloc_control *rc,
1117                               struct btrfs_root *src,
1118                               struct btrfs_root *dest)
1119 {
1120         struct btrfs_root *reloc_root = src->reloc_root;
1121         struct backref_cache *cache = &rc->backref_cache;
1122         struct backref_node *node = NULL;
1123         struct backref_node *new_node;
1124         struct backref_edge *edge;
1125         struct backref_edge *new_edge;
1126         struct rb_node *rb_node;
1127
1128         if (cache->last_trans > 0)
1129                 update_backref_cache(trans, cache);
1130
1131         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1132         if (rb_node) {
1133                 node = rb_entry(rb_node, struct backref_node, rb_node);
1134                 if (node->detached)
1135                         node = NULL;
1136                 else
1137                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1138         }
1139
1140         if (!node) {
1141                 rb_node = tree_search(&cache->rb_root,
1142                                       reloc_root->commit_root->start);
1143                 if (rb_node) {
1144                         node = rb_entry(rb_node, struct backref_node,
1145                                         rb_node);
1146                         BUG_ON(node->detached);
1147                 }
1148         }
1149
1150         if (!node)
1151                 return 0;
1152
1153         new_node = alloc_backref_node(cache);
1154         if (!new_node)
1155                 return -ENOMEM;
1156
1157         new_node->bytenr = dest->node->start;
1158         new_node->level = node->level;
1159         new_node->lowest = node->lowest;
1160         new_node->checked = 1;
1161         new_node->root = dest;
1162
1163         if (!node->lowest) {
1164                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1165                         new_edge = alloc_backref_edge(cache);
1166                         if (!new_edge)
1167                                 goto fail;
1168
1169                         new_edge->node[UPPER] = new_node;
1170                         new_edge->node[LOWER] = edge->node[LOWER];
1171                         list_add_tail(&new_edge->list[UPPER],
1172                                       &new_node->lower);
1173                 }
1174         }
1175
1176         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1177                               &new_node->rb_node);
1178         BUG_ON(rb_node);
1179
1180         if (!new_node->lowest) {
1181                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1182                         list_add_tail(&new_edge->list[LOWER],
1183                                       &new_edge->node[LOWER]->upper);
1184                 }
1185         }
1186         return 0;
1187 fail:
1188         while (!list_empty(&new_node->lower)) {
1189                 new_edge = list_entry(new_node->lower.next,
1190                                       struct backref_edge, list[UPPER]);
1191                 list_del(&new_edge->list[UPPER]);
1192                 free_backref_edge(cache, new_edge);
1193         }
1194         free_backref_node(cache, new_node);
1195         return -ENOMEM;
1196 }
1197
1198 /*
1199  * helper to add 'address of tree root -> reloc tree' mapping
1200  */
1201 static int __add_reloc_root(struct btrfs_root *root)
1202 {
1203         struct rb_node *rb_node;
1204         struct mapping_node *node;
1205         struct reloc_control *rc = root->fs_info->reloc_ctl;
1206
1207         node = kmalloc(sizeof(*node), GFP_NOFS);
1208         BUG_ON(!node);
1209
1210         node->bytenr = root->node->start;
1211         node->data = root;
1212
1213         spin_lock(&rc->reloc_root_tree.lock);
1214         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1215                               node->bytenr, &node->rb_node);
1216         spin_unlock(&rc->reloc_root_tree.lock);
1217         BUG_ON(rb_node);
1218
1219         list_add_tail(&root->root_list, &rc->reloc_roots);
1220         return 0;
1221 }
1222
1223 /*
1224  * helper to update/delete the 'address of tree root -> reloc tree'
1225  * mapping
1226  */
1227 static int __update_reloc_root(struct btrfs_root *root, int del)
1228 {
1229         struct rb_node *rb_node;
1230         struct mapping_node *node = NULL;
1231         struct reloc_control *rc = root->fs_info->reloc_ctl;
1232
1233         spin_lock(&rc->reloc_root_tree.lock);
1234         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1235                               root->commit_root->start);
1236         if (rb_node) {
1237                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1238                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1239         }
1240         spin_unlock(&rc->reloc_root_tree.lock);
1241
1242         BUG_ON((struct btrfs_root *)node->data != root);
1243
1244         if (!del) {
1245                 spin_lock(&rc->reloc_root_tree.lock);
1246                 node->bytenr = root->node->start;
1247                 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1248                                       node->bytenr, &node->rb_node);
1249                 spin_unlock(&rc->reloc_root_tree.lock);
1250                 BUG_ON(rb_node);
1251         } else {
1252                 list_del_init(&root->root_list);
1253                 kfree(node);
1254         }
1255         return 0;
1256 }
1257
1258 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1259                                         struct btrfs_root *root, u64 objectid)
1260 {
1261         struct btrfs_root *reloc_root;
1262         struct extent_buffer *eb;
1263         struct btrfs_root_item *root_item;
1264         struct btrfs_key root_key;
1265         int ret;
1266
1267         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1268         BUG_ON(!root_item);
1269
1270         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1271         root_key.type = BTRFS_ROOT_ITEM_KEY;
1272         root_key.offset = objectid;
1273
1274         if (root->root_key.objectid == objectid) {
1275                 /* called by btrfs_init_reloc_root */
1276                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1277                                       BTRFS_TREE_RELOC_OBJECTID);
1278                 BUG_ON(ret);
1279
1280                 btrfs_set_root_last_snapshot(&root->root_item,
1281                                              trans->transid - 1);
1282         } else {
1283                 /*
1284                  * called by btrfs_reloc_post_snapshot_hook.
1285                  * the source tree is a reloc tree, all tree blocks
1286                  * modified after it was created have RELOC flag
1287                  * set in their headers. so it's OK to not update
1288                  * the 'last_snapshot'.
1289                  */
1290                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1291                                       BTRFS_TREE_RELOC_OBJECTID);
1292                 BUG_ON(ret);
1293         }
1294
1295         memcpy(root_item, &root->root_item, sizeof(*root_item));
1296         btrfs_set_root_bytenr(root_item, eb->start);
1297         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1298         btrfs_set_root_generation(root_item, trans->transid);
1299
1300         if (root->root_key.objectid == objectid) {
1301                 btrfs_set_root_refs(root_item, 0);
1302                 memset(&root_item->drop_progress, 0,
1303                        sizeof(struct btrfs_disk_key));
1304                 root_item->drop_level = 0;
1305         }
1306
1307         btrfs_tree_unlock(eb);
1308         free_extent_buffer(eb);
1309
1310         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1311                                 &root_key, root_item);
1312         BUG_ON(ret);
1313         kfree(root_item);
1314
1315         reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
1316                                                  &root_key);
1317         BUG_ON(IS_ERR(reloc_root));
1318         reloc_root->last_trans = trans->transid;
1319         return reloc_root;
1320 }
1321
1322 /*
1323  * create reloc tree for a given fs tree. reloc tree is just a
1324  * snapshot of the fs tree with special root objectid.
1325  */
1326 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1327                           struct btrfs_root *root)
1328 {
1329         struct btrfs_root *reloc_root;
1330         struct reloc_control *rc = root->fs_info->reloc_ctl;
1331         int clear_rsv = 0;
1332
1333         if (root->reloc_root) {
1334                 reloc_root = root->reloc_root;
1335                 reloc_root->last_trans = trans->transid;
1336                 return 0;
1337         }
1338
1339         if (!rc || !rc->create_reloc_tree ||
1340             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1341                 return 0;
1342
1343         if (!trans->block_rsv) {
1344                 trans->block_rsv = rc->block_rsv;
1345                 clear_rsv = 1;
1346         }
1347         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1348         if (clear_rsv)
1349                 trans->block_rsv = NULL;
1350
1351         __add_reloc_root(reloc_root);
1352         root->reloc_root = reloc_root;
1353         return 0;
1354 }
1355
1356 /*
1357  * update root item of reloc tree
1358  */
1359 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1360                             struct btrfs_root *root)
1361 {
1362         struct btrfs_root *reloc_root;
1363         struct btrfs_root_item *root_item;
1364         int del = 0;
1365         int ret;
1366
1367         if (!root->reloc_root)
1368                 return 0;
1369
1370         reloc_root = root->reloc_root;
1371         root_item = &reloc_root->root_item;
1372
1373         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1374             btrfs_root_refs(root_item) == 0) {
1375                 root->reloc_root = NULL;
1376                 del = 1;
1377         }
1378
1379         __update_reloc_root(reloc_root, del);
1380
1381         if (reloc_root->commit_root != reloc_root->node) {
1382                 btrfs_set_root_node(root_item, reloc_root->node);
1383                 free_extent_buffer(reloc_root->commit_root);
1384                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1385         }
1386
1387         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1388                                 &reloc_root->root_key, root_item);
1389         BUG_ON(ret);
1390         return 0;
1391 }
1392
1393 /*
1394  * helper to find first cached inode with inode number >= objectid
1395  * in a subvolume
1396  */
1397 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1398 {
1399         struct rb_node *node;
1400         struct rb_node *prev;
1401         struct btrfs_inode *entry;
1402         struct inode *inode;
1403
1404         spin_lock(&root->inode_lock);
1405 again:
1406         node = root->inode_tree.rb_node;
1407         prev = NULL;
1408         while (node) {
1409                 prev = node;
1410                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1411
1412                 if (objectid < entry->vfs_inode.i_ino)
1413                         node = node->rb_left;
1414                 else if (objectid > entry->vfs_inode.i_ino)
1415                         node = node->rb_right;
1416                 else
1417                         break;
1418         }
1419         if (!node) {
1420                 while (prev) {
1421                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1422                         if (objectid <= entry->vfs_inode.i_ino) {
1423                                 node = prev;
1424                                 break;
1425                         }
1426                         prev = rb_next(prev);
1427                 }
1428         }
1429         while (node) {
1430                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1431                 inode = igrab(&entry->vfs_inode);
1432                 if (inode) {
1433                         spin_unlock(&root->inode_lock);
1434                         return inode;
1435                 }
1436
1437                 objectid = entry->vfs_inode.i_ino + 1;
1438                 if (cond_resched_lock(&root->inode_lock))
1439                         goto again;
1440
1441                 node = rb_next(node);
1442         }
1443         spin_unlock(&root->inode_lock);
1444         return NULL;
1445 }
1446
1447 static int in_block_group(u64 bytenr,
1448                           struct btrfs_block_group_cache *block_group)
1449 {
1450         if (bytenr >= block_group->key.objectid &&
1451             bytenr < block_group->key.objectid + block_group->key.offset)
1452                 return 1;
1453         return 0;
1454 }
1455
1456 /*
1457  * get new location of data
1458  */
1459 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1460                             u64 bytenr, u64 num_bytes)
1461 {
1462         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1463         struct btrfs_path *path;
1464         struct btrfs_file_extent_item *fi;
1465         struct extent_buffer *leaf;
1466         int ret;
1467
1468         path = btrfs_alloc_path();
1469         if (!path)
1470                 return -ENOMEM;
1471
1472         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1473         ret = btrfs_lookup_file_extent(NULL, root, path, reloc_inode->i_ino,
1474                                        bytenr, 0);
1475         if (ret < 0)
1476                 goto out;
1477         if (ret > 0) {
1478                 ret = -ENOENT;
1479                 goto out;
1480         }
1481
1482         leaf = path->nodes[0];
1483         fi = btrfs_item_ptr(leaf, path->slots[0],
1484                             struct btrfs_file_extent_item);
1485
1486         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1487                btrfs_file_extent_compression(leaf, fi) ||
1488                btrfs_file_extent_encryption(leaf, fi) ||
1489                btrfs_file_extent_other_encoding(leaf, fi));
1490
1491         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1492                 ret = 1;
1493                 goto out;
1494         }
1495
1496         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1497         ret = 0;
1498 out:
1499         btrfs_free_path(path);
1500         return ret;
1501 }
1502
1503 /*
1504  * update file extent items in the tree leaf to point to
1505  * the new locations.
1506  */
1507 static noinline_for_stack
1508 int replace_file_extents(struct btrfs_trans_handle *trans,
1509                          struct reloc_control *rc,
1510                          struct btrfs_root *root,
1511                          struct extent_buffer *leaf)
1512 {
1513         struct btrfs_key key;
1514         struct btrfs_file_extent_item *fi;
1515         struct inode *inode = NULL;
1516         u64 parent;
1517         u64 bytenr;
1518         u64 new_bytenr = 0;
1519         u64 num_bytes;
1520         u64 end;
1521         u32 nritems;
1522         u32 i;
1523         int ret;
1524         int first = 1;
1525         int dirty = 0;
1526
1527         if (rc->stage != UPDATE_DATA_PTRS)
1528                 return 0;
1529
1530         /* reloc trees always use full backref */
1531         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1532                 parent = leaf->start;
1533         else
1534                 parent = 0;
1535
1536         nritems = btrfs_header_nritems(leaf);
1537         for (i = 0; i < nritems; i++) {
1538                 cond_resched();
1539                 btrfs_item_key_to_cpu(leaf, &key, i);
1540                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1541                         continue;
1542                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1543                 if (btrfs_file_extent_type(leaf, fi) ==
1544                     BTRFS_FILE_EXTENT_INLINE)
1545                         continue;
1546                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1547                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1548                 if (bytenr == 0)
1549                         continue;
1550                 if (!in_block_group(bytenr, rc->block_group))
1551                         continue;
1552
1553                 /*
1554                  * if we are modifying block in fs tree, wait for readpage
1555                  * to complete and drop the extent cache
1556                  */
1557                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1558                         if (first) {
1559                                 inode = find_next_inode(root, key.objectid);
1560                                 first = 0;
1561                         } else if (inode && inode->i_ino < key.objectid) {
1562                                 btrfs_add_delayed_iput(inode);
1563                                 inode = find_next_inode(root, key.objectid);
1564                         }
1565                         if (inode && inode->i_ino == key.objectid) {
1566                                 end = key.offset +
1567                                       btrfs_file_extent_num_bytes(leaf, fi);
1568                                 WARN_ON(!IS_ALIGNED(key.offset,
1569                                                     root->sectorsize));
1570                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1571                                 end--;
1572                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1573                                                       key.offset, end,
1574                                                       GFP_NOFS);
1575                                 if (!ret)
1576                                         continue;
1577
1578                                 btrfs_drop_extent_cache(inode, key.offset, end,
1579                                                         1);
1580                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1581                                               key.offset, end, GFP_NOFS);
1582                         }
1583                 }
1584
1585                 ret = get_new_location(rc->data_inode, &new_bytenr,
1586                                        bytenr, num_bytes);
1587                 if (ret > 0) {
1588                         WARN_ON(1);
1589                         continue;
1590                 }
1591                 BUG_ON(ret < 0);
1592
1593                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1594                 dirty = 1;
1595
1596                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1597                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1598                                            num_bytes, parent,
1599                                            btrfs_header_owner(leaf),
1600                                            key.objectid, key.offset);
1601                 BUG_ON(ret);
1602
1603                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1604                                         parent, btrfs_header_owner(leaf),
1605                                         key.objectid, key.offset);
1606                 BUG_ON(ret);
1607         }
1608         if (dirty)
1609                 btrfs_mark_buffer_dirty(leaf);
1610         if (inode)
1611                 btrfs_add_delayed_iput(inode);
1612         return 0;
1613 }
1614
1615 static noinline_for_stack
1616 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1617                      struct btrfs_path *path, int level)
1618 {
1619         struct btrfs_disk_key key1;
1620         struct btrfs_disk_key key2;
1621         btrfs_node_key(eb, &key1, slot);
1622         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1623         return memcmp(&key1, &key2, sizeof(key1));
1624 }
1625
1626 /*
1627  * try to replace tree blocks in fs tree with the new blocks
1628  * in reloc tree. tree blocks haven't been modified since the
1629  * reloc tree was create can be replaced.
1630  *
1631  * if a block was replaced, level of the block + 1 is returned.
1632  * if no block got replaced, 0 is returned. if there are other
1633  * errors, a negative error number is returned.
1634  */
1635 static noinline_for_stack
1636 int replace_path(struct btrfs_trans_handle *trans,
1637                  struct btrfs_root *dest, struct btrfs_root *src,
1638                  struct btrfs_path *path, struct btrfs_key *next_key,
1639                  int lowest_level, int max_level)
1640 {
1641         struct extent_buffer *eb;
1642         struct extent_buffer *parent;
1643         struct btrfs_key key;
1644         u64 old_bytenr;
1645         u64 new_bytenr;
1646         u64 old_ptr_gen;
1647         u64 new_ptr_gen;
1648         u64 last_snapshot;
1649         u32 blocksize;
1650         int cow = 0;
1651         int level;
1652         int ret;
1653         int slot;
1654
1655         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1656         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1657
1658         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1659 again:
1660         slot = path->slots[lowest_level];
1661         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1662
1663         eb = btrfs_lock_root_node(dest);
1664         btrfs_set_lock_blocking(eb);
1665         level = btrfs_header_level(eb);
1666
1667         if (level < lowest_level) {
1668                 btrfs_tree_unlock(eb);
1669                 free_extent_buffer(eb);
1670                 return 0;
1671         }
1672
1673         if (cow) {
1674                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1675                 BUG_ON(ret);
1676         }
1677         btrfs_set_lock_blocking(eb);
1678
1679         if (next_key) {
1680                 next_key->objectid = (u64)-1;
1681                 next_key->type = (u8)-1;
1682                 next_key->offset = (u64)-1;
1683         }
1684
1685         parent = eb;
1686         while (1) {
1687                 level = btrfs_header_level(parent);
1688                 BUG_ON(level < lowest_level);
1689
1690                 ret = btrfs_bin_search(parent, &key, level, &slot);
1691                 if (ret && slot > 0)
1692                         slot--;
1693
1694                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1695                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1696
1697                 old_bytenr = btrfs_node_blockptr(parent, slot);
1698                 blocksize = btrfs_level_size(dest, level - 1);
1699                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1700
1701                 if (level <= max_level) {
1702                         eb = path->nodes[level];
1703                         new_bytenr = btrfs_node_blockptr(eb,
1704                                                         path->slots[level]);
1705                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1706                                                         path->slots[level]);
1707                 } else {
1708                         new_bytenr = 0;
1709                         new_ptr_gen = 0;
1710                 }
1711
1712                 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1713                         WARN_ON(1);
1714                         ret = level;
1715                         break;
1716                 }
1717
1718                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1719                     memcmp_node_keys(parent, slot, path, level)) {
1720                         if (level <= lowest_level) {
1721                                 ret = 0;
1722                                 break;
1723                         }
1724
1725                         eb = read_tree_block(dest, old_bytenr, blocksize,
1726                                              old_ptr_gen);
1727                         btrfs_tree_lock(eb);
1728                         if (cow) {
1729                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1730                                                       slot, &eb);
1731                                 BUG_ON(ret);
1732                         }
1733                         btrfs_set_lock_blocking(eb);
1734
1735                         btrfs_tree_unlock(parent);
1736                         free_extent_buffer(parent);
1737
1738                         parent = eb;
1739                         continue;
1740                 }
1741
1742                 if (!cow) {
1743                         btrfs_tree_unlock(parent);
1744                         free_extent_buffer(parent);
1745                         cow = 1;
1746                         goto again;
1747                 }
1748
1749                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1750                                       path->slots[level]);
1751                 btrfs_release_path(src, path);
1752
1753                 path->lowest_level = level;
1754                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1755                 path->lowest_level = 0;
1756                 BUG_ON(ret);
1757
1758                 /*
1759                  * swap blocks in fs tree and reloc tree.
1760                  */
1761                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1762                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1763                 btrfs_mark_buffer_dirty(parent);
1764
1765                 btrfs_set_node_blockptr(path->nodes[level],
1766                                         path->slots[level], old_bytenr);
1767                 btrfs_set_node_ptr_generation(path->nodes[level],
1768                                               path->slots[level], old_ptr_gen);
1769                 btrfs_mark_buffer_dirty(path->nodes[level]);
1770
1771                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1772                                         path->nodes[level]->start,
1773                                         src->root_key.objectid, level - 1, 0);
1774                 BUG_ON(ret);
1775                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1776                                         0, dest->root_key.objectid, level - 1,
1777                                         0);
1778                 BUG_ON(ret);
1779
1780                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1781                                         path->nodes[level]->start,
1782                                         src->root_key.objectid, level - 1, 0);
1783                 BUG_ON(ret);
1784
1785                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1786                                         0, dest->root_key.objectid, level - 1,
1787                                         0);
1788                 BUG_ON(ret);
1789
1790                 btrfs_unlock_up_safe(path, 0);
1791
1792                 ret = level;
1793                 break;
1794         }
1795         btrfs_tree_unlock(parent);
1796         free_extent_buffer(parent);
1797         return ret;
1798 }
1799
1800 /*
1801  * helper to find next relocated block in reloc tree
1802  */
1803 static noinline_for_stack
1804 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1805                        int *level)
1806 {
1807         struct extent_buffer *eb;
1808         int i;
1809         u64 last_snapshot;
1810         u32 nritems;
1811
1812         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1813
1814         for (i = 0; i < *level; i++) {
1815                 free_extent_buffer(path->nodes[i]);
1816                 path->nodes[i] = NULL;
1817         }
1818
1819         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1820                 eb = path->nodes[i];
1821                 nritems = btrfs_header_nritems(eb);
1822                 while (path->slots[i] + 1 < nritems) {
1823                         path->slots[i]++;
1824                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1825                             last_snapshot)
1826                                 continue;
1827
1828                         *level = i;
1829                         return 0;
1830                 }
1831                 free_extent_buffer(path->nodes[i]);
1832                 path->nodes[i] = NULL;
1833         }
1834         return 1;
1835 }
1836
1837 /*
1838  * walk down reloc tree to find relocated block of lowest level
1839  */
1840 static noinline_for_stack
1841 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1842                          int *level)
1843 {
1844         struct extent_buffer *eb = NULL;
1845         int i;
1846         u64 bytenr;
1847         u64 ptr_gen = 0;
1848         u64 last_snapshot;
1849         u32 blocksize;
1850         u32 nritems;
1851
1852         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1853
1854         for (i = *level; i > 0; i--) {
1855                 eb = path->nodes[i];
1856                 nritems = btrfs_header_nritems(eb);
1857                 while (path->slots[i] < nritems) {
1858                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1859                         if (ptr_gen > last_snapshot)
1860                                 break;
1861                         path->slots[i]++;
1862                 }
1863                 if (path->slots[i] >= nritems) {
1864                         if (i == *level)
1865                                 break;
1866                         *level = i + 1;
1867                         return 0;
1868                 }
1869                 if (i == 1) {
1870                         *level = i;
1871                         return 0;
1872                 }
1873
1874                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1875                 blocksize = btrfs_level_size(root, i - 1);
1876                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1877                 BUG_ON(btrfs_header_level(eb) != i - 1);
1878                 path->nodes[i - 1] = eb;
1879                 path->slots[i - 1] = 0;
1880         }
1881         return 1;
1882 }
1883
1884 /*
1885  * invalidate extent cache for file extents whose key in range of
1886  * [min_key, max_key)
1887  */
1888 static int invalidate_extent_cache(struct btrfs_root *root,
1889                                    struct btrfs_key *min_key,
1890                                    struct btrfs_key *max_key)
1891 {
1892         struct inode *inode = NULL;
1893         u64 objectid;
1894         u64 start, end;
1895
1896         objectid = min_key->objectid;
1897         while (1) {
1898                 cond_resched();
1899                 iput(inode);
1900
1901                 if (objectid > max_key->objectid)
1902                         break;
1903
1904                 inode = find_next_inode(root, objectid);
1905                 if (!inode)
1906                         break;
1907
1908                 if (inode->i_ino > max_key->objectid) {
1909                         iput(inode);
1910                         break;
1911                 }
1912
1913                 objectid = inode->i_ino + 1;
1914                 if (!S_ISREG(inode->i_mode))
1915                         continue;
1916
1917                 if (unlikely(min_key->objectid == inode->i_ino)) {
1918                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1919                                 continue;
1920                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1921                                 start = 0;
1922                         else {
1923                                 start = min_key->offset;
1924                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1925                         }
1926                 } else {
1927                         start = 0;
1928                 }
1929
1930                 if (unlikely(max_key->objectid == inode->i_ino)) {
1931                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1932                                 continue;
1933                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1934                                 end = (u64)-1;
1935                         } else {
1936                                 if (max_key->offset == 0)
1937                                         continue;
1938                                 end = max_key->offset;
1939                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1940                                 end--;
1941                         }
1942                 } else {
1943                         end = (u64)-1;
1944                 }
1945
1946                 /* the lock_extent waits for readpage to complete */
1947                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1948                 btrfs_drop_extent_cache(inode, start, end, 1);
1949                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1950         }
1951         return 0;
1952 }
1953
1954 static int find_next_key(struct btrfs_path *path, int level,
1955                          struct btrfs_key *key)
1956
1957 {
1958         while (level < BTRFS_MAX_LEVEL) {
1959                 if (!path->nodes[level])
1960                         break;
1961                 if (path->slots[level] + 1 <
1962                     btrfs_header_nritems(path->nodes[level])) {
1963                         btrfs_node_key_to_cpu(path->nodes[level], key,
1964                                               path->slots[level] + 1);
1965                         return 0;
1966                 }
1967                 level++;
1968         }
1969         return 1;
1970 }
1971
1972 /*
1973  * merge the relocated tree blocks in reloc tree with corresponding
1974  * fs tree.
1975  */
1976 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
1977                                                struct btrfs_root *root)
1978 {
1979         LIST_HEAD(inode_list);
1980         struct btrfs_key key;
1981         struct btrfs_key next_key;
1982         struct btrfs_trans_handle *trans;
1983         struct btrfs_root *reloc_root;
1984         struct btrfs_root_item *root_item;
1985         struct btrfs_path *path;
1986         struct extent_buffer *leaf;
1987         unsigned long nr;
1988         int level;
1989         int max_level;
1990         int replaced = 0;
1991         int ret;
1992         int err = 0;
1993         u32 min_reserved;
1994
1995         path = btrfs_alloc_path();
1996         if (!path)
1997                 return -ENOMEM;
1998
1999         reloc_root = root->reloc_root;
2000         root_item = &reloc_root->root_item;
2001
2002         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2003                 level = btrfs_root_level(root_item);
2004                 extent_buffer_get(reloc_root->node);
2005                 path->nodes[level] = reloc_root->node;
2006                 path->slots[level] = 0;
2007         } else {
2008                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2009
2010                 level = root_item->drop_level;
2011                 BUG_ON(level == 0);
2012                 path->lowest_level = level;
2013                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2014                 path->lowest_level = 0;
2015                 if (ret < 0) {
2016                         btrfs_free_path(path);
2017                         return ret;
2018                 }
2019
2020                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2021                                       path->slots[level]);
2022                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2023
2024                 btrfs_unlock_up_safe(path, 0);
2025         }
2026
2027         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2028         memset(&next_key, 0, sizeof(next_key));
2029
2030         while (1) {
2031                 trans = btrfs_start_transaction(root, 0);
2032                 BUG_ON(IS_ERR(trans));
2033                 trans->block_rsv = rc->block_rsv;
2034
2035                 ret = btrfs_block_rsv_check(trans, root, rc->block_rsv,
2036                                             min_reserved, 0);
2037                 if (ret) {
2038                         BUG_ON(ret != -EAGAIN);
2039                         ret = btrfs_commit_transaction(trans, root);
2040                         BUG_ON(ret);
2041                         continue;
2042                 }
2043
2044                 replaced = 0;
2045                 max_level = level;
2046
2047                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2048                 if (ret < 0) {
2049                         err = ret;
2050                         goto out;
2051                 }
2052                 if (ret > 0)
2053                         break;
2054
2055                 if (!find_next_key(path, level, &key) &&
2056                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2057                         ret = 0;
2058                 } else {
2059                         ret = replace_path(trans, root, reloc_root, path,
2060                                            &next_key, level, max_level);
2061                 }
2062                 if (ret < 0) {
2063                         err = ret;
2064                         goto out;
2065                 }
2066
2067                 if (ret > 0) {
2068                         level = ret;
2069                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2070                                               path->slots[level]);
2071                         replaced = 1;
2072                 }
2073
2074                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2075                 if (ret > 0)
2076                         break;
2077
2078                 BUG_ON(level == 0);
2079                 /*
2080                  * save the merging progress in the drop_progress.
2081                  * this is OK since root refs == 1 in this case.
2082                  */
2083                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2084                                path->slots[level]);
2085                 root_item->drop_level = level;
2086
2087                 nr = trans->blocks_used;
2088                 btrfs_end_transaction_throttle(trans, root);
2089
2090                 btrfs_btree_balance_dirty(root, nr);
2091
2092                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2093                         invalidate_extent_cache(root, &key, &next_key);
2094         }
2095
2096         /*
2097          * handle the case only one block in the fs tree need to be
2098          * relocated and the block is tree root.
2099          */
2100         leaf = btrfs_lock_root_node(root);
2101         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2102         btrfs_tree_unlock(leaf);
2103         free_extent_buffer(leaf);
2104         if (ret < 0)
2105                 err = ret;
2106 out:
2107         btrfs_free_path(path);
2108
2109         if (err == 0) {
2110                 memset(&root_item->drop_progress, 0,
2111                        sizeof(root_item->drop_progress));
2112                 root_item->drop_level = 0;
2113                 btrfs_set_root_refs(root_item, 0);
2114                 btrfs_update_reloc_root(trans, root);
2115         }
2116
2117         nr = trans->blocks_used;
2118         btrfs_end_transaction_throttle(trans, root);
2119
2120         btrfs_btree_balance_dirty(root, nr);
2121
2122         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2123                 invalidate_extent_cache(root, &key, &next_key);
2124
2125         return err;
2126 }
2127
2128 static noinline_for_stack
2129 int prepare_to_merge(struct reloc_control *rc, int err)
2130 {
2131         struct btrfs_root *root = rc->extent_root;
2132         struct btrfs_root *reloc_root;
2133         struct btrfs_trans_handle *trans;
2134         LIST_HEAD(reloc_roots);
2135         u64 num_bytes = 0;
2136         int ret;
2137
2138         mutex_lock(&root->fs_info->trans_mutex);
2139         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2140         rc->merging_rsv_size += rc->nodes_relocated * 2;
2141         mutex_unlock(&root->fs_info->trans_mutex);
2142 again:
2143         if (!err) {
2144                 num_bytes = rc->merging_rsv_size;
2145                 ret = btrfs_block_rsv_add(NULL, root, rc->block_rsv,
2146                                           num_bytes);
2147                 if (ret)
2148                         err = ret;
2149         }
2150
2151         trans = btrfs_join_transaction(rc->extent_root, 1);
2152         if (IS_ERR(trans)) {
2153                 if (!err)
2154                         btrfs_block_rsv_release(rc->extent_root,
2155                                                 rc->block_rsv, num_bytes);
2156                 return PTR_ERR(trans);
2157         }
2158
2159         if (!err) {
2160                 if (num_bytes != rc->merging_rsv_size) {
2161                         btrfs_end_transaction(trans, rc->extent_root);
2162                         btrfs_block_rsv_release(rc->extent_root,
2163                                                 rc->block_rsv, num_bytes);
2164                         goto again;
2165                 }
2166         }
2167
2168         rc->merge_reloc_tree = 1;
2169
2170         while (!list_empty(&rc->reloc_roots)) {
2171                 reloc_root = list_entry(rc->reloc_roots.next,
2172                                         struct btrfs_root, root_list);
2173                 list_del_init(&reloc_root->root_list);
2174
2175                 root = read_fs_root(reloc_root->fs_info,
2176                                     reloc_root->root_key.offset);
2177                 BUG_ON(IS_ERR(root));
2178                 BUG_ON(root->reloc_root != reloc_root);
2179
2180                 /*
2181                  * set reference count to 1, so btrfs_recover_relocation
2182                  * knows it should resumes merging
2183                  */
2184                 if (!err)
2185                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2186                 btrfs_update_reloc_root(trans, root);
2187
2188                 list_add(&reloc_root->root_list, &reloc_roots);
2189         }
2190
2191         list_splice(&reloc_roots, &rc->reloc_roots);
2192
2193         if (!err)
2194                 btrfs_commit_transaction(trans, rc->extent_root);
2195         else
2196                 btrfs_end_transaction(trans, rc->extent_root);
2197         return err;
2198 }
2199
2200 static noinline_for_stack
2201 int merge_reloc_roots(struct reloc_control *rc)
2202 {
2203         struct btrfs_root *root;
2204         struct btrfs_root *reloc_root;
2205         LIST_HEAD(reloc_roots);
2206         int found = 0;
2207         int ret;
2208 again:
2209         root = rc->extent_root;
2210         mutex_lock(&root->fs_info->trans_mutex);
2211         list_splice_init(&rc->reloc_roots, &reloc_roots);
2212         mutex_unlock(&root->fs_info->trans_mutex);
2213
2214         while (!list_empty(&reloc_roots)) {
2215                 found = 1;
2216                 reloc_root = list_entry(reloc_roots.next,
2217                                         struct btrfs_root, root_list);
2218
2219                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2220                         root = read_fs_root(reloc_root->fs_info,
2221                                             reloc_root->root_key.offset);
2222                         BUG_ON(IS_ERR(root));
2223                         BUG_ON(root->reloc_root != reloc_root);
2224
2225                         ret = merge_reloc_root(rc, root);
2226                         BUG_ON(ret);
2227                 } else {
2228                         list_del_init(&reloc_root->root_list);
2229                 }
2230                 btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
2231         }
2232
2233         if (found) {
2234                 found = 0;
2235                 goto again;
2236         }
2237         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2238         return 0;
2239 }
2240
2241 static void free_block_list(struct rb_root *blocks)
2242 {
2243         struct tree_block *block;
2244         struct rb_node *rb_node;
2245         while ((rb_node = rb_first(blocks))) {
2246                 block = rb_entry(rb_node, struct tree_block, rb_node);
2247                 rb_erase(rb_node, blocks);
2248                 kfree(block);
2249         }
2250 }
2251
2252 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2253                                       struct btrfs_root *reloc_root)
2254 {
2255         struct btrfs_root *root;
2256
2257         if (reloc_root->last_trans == trans->transid)
2258                 return 0;
2259
2260         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2261         BUG_ON(IS_ERR(root));
2262         BUG_ON(root->reloc_root != reloc_root);
2263
2264         return btrfs_record_root_in_trans(trans, root);
2265 }
2266
2267 static noinline_for_stack
2268 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2269                                      struct reloc_control *rc,
2270                                      struct backref_node *node,
2271                                      struct backref_edge *edges[], int *nr)
2272 {
2273         struct backref_node *next;
2274         struct btrfs_root *root;
2275         int index = 0;
2276
2277         next = node;
2278         while (1) {
2279                 cond_resched();
2280                 next = walk_up_backref(next, edges, &index);
2281                 root = next->root;
2282                 BUG_ON(!root);
2283                 BUG_ON(!root->ref_cows);
2284
2285                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2286                         record_reloc_root_in_trans(trans, root);
2287                         break;
2288                 }
2289
2290                 btrfs_record_root_in_trans(trans, root);
2291                 root = root->reloc_root;
2292
2293                 if (next->new_bytenr != root->node->start) {
2294                         BUG_ON(next->new_bytenr);
2295                         BUG_ON(!list_empty(&next->list));
2296                         next->new_bytenr = root->node->start;
2297                         next->root = root;
2298                         list_add_tail(&next->list,
2299                                       &rc->backref_cache.changed);
2300                         __mark_block_processed(rc, next);
2301                         break;
2302                 }
2303
2304                 WARN_ON(1);
2305                 root = NULL;
2306                 next = walk_down_backref(edges, &index);
2307                 if (!next || next->level <= node->level)
2308                         break;
2309         }
2310         if (!root)
2311                 return NULL;
2312
2313         *nr = index;
2314         next = node;
2315         /* setup backref node path for btrfs_reloc_cow_block */
2316         while (1) {
2317                 rc->backref_cache.path[next->level] = next;
2318                 if (--index < 0)
2319                         break;
2320                 next = edges[index]->node[UPPER];
2321         }
2322         return root;
2323 }
2324
2325 /*
2326  * select a tree root for relocation. return NULL if the block
2327  * is reference counted. we should use do_relocation() in this
2328  * case. return a tree root pointer if the block isn't reference
2329  * counted. return -ENOENT if the block is root of reloc tree.
2330  */
2331 static noinline_for_stack
2332 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2333                                    struct backref_node *node)
2334 {
2335         struct backref_node *next;
2336         struct btrfs_root *root;
2337         struct btrfs_root *fs_root = NULL;
2338         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2339         int index = 0;
2340
2341         next = node;
2342         while (1) {
2343                 cond_resched();
2344                 next = walk_up_backref(next, edges, &index);
2345                 root = next->root;
2346                 BUG_ON(!root);
2347
2348                 /* no other choice for non-refernce counted tree */
2349                 if (!root->ref_cows)
2350                         return root;
2351
2352                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2353                         fs_root = root;
2354
2355                 if (next != node)
2356                         return NULL;
2357
2358                 next = walk_down_backref(edges, &index);
2359                 if (!next || next->level <= node->level)
2360                         break;
2361         }
2362
2363         if (!fs_root)
2364                 return ERR_PTR(-ENOENT);
2365         return fs_root;
2366 }
2367
2368 static noinline_for_stack
2369 u64 calcu_metadata_size(struct reloc_control *rc,
2370                         struct backref_node *node, int reserve)
2371 {
2372         struct backref_node *next = node;
2373         struct backref_edge *edge;
2374         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2375         u64 num_bytes = 0;
2376         int index = 0;
2377
2378         BUG_ON(reserve && node->processed);
2379
2380         while (next) {
2381                 cond_resched();
2382                 while (1) {
2383                         if (next->processed && (reserve || next != node))
2384                                 break;
2385
2386                         num_bytes += btrfs_level_size(rc->extent_root,
2387                                                       next->level);
2388
2389                         if (list_empty(&next->upper))
2390                                 break;
2391
2392                         edge = list_entry(next->upper.next,
2393                                           struct backref_edge, list[LOWER]);
2394                         edges[index++] = edge;
2395                         next = edge->node[UPPER];
2396                 }
2397                 next = walk_down_backref(edges, &index);
2398         }
2399         return num_bytes;
2400 }
2401
2402 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2403                                   struct reloc_control *rc,
2404                                   struct backref_node *node)
2405 {
2406         struct btrfs_root *root = rc->extent_root;
2407         u64 num_bytes;
2408         int ret;
2409
2410         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2411
2412         trans->block_rsv = rc->block_rsv;
2413         ret = btrfs_block_rsv_add(trans, root, rc->block_rsv, num_bytes);
2414         if (ret) {
2415                 if (ret == -EAGAIN)
2416                         rc->commit_transaction = 1;
2417                 return ret;
2418         }
2419
2420         return 0;
2421 }
2422
2423 static void release_metadata_space(struct reloc_control *rc,
2424                                    struct backref_node *node)
2425 {
2426         u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2427         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2428 }
2429
2430 /*
2431  * relocate a block tree, and then update pointers in upper level
2432  * blocks that reference the block to point to the new location.
2433  *
2434  * if called by link_to_upper, the block has already been relocated.
2435  * in that case this function just updates pointers.
2436  */
2437 static int do_relocation(struct btrfs_trans_handle *trans,
2438                          struct reloc_control *rc,
2439                          struct backref_node *node,
2440                          struct btrfs_key *key,
2441                          struct btrfs_path *path, int lowest)
2442 {
2443         struct backref_node *upper;
2444         struct backref_edge *edge;
2445         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2446         struct btrfs_root *root;
2447         struct extent_buffer *eb;
2448         u32 blocksize;
2449         u64 bytenr;
2450         u64 generation;
2451         int nr;
2452         int slot;
2453         int ret;
2454         int err = 0;
2455
2456         BUG_ON(lowest && node->eb);
2457
2458         path->lowest_level = node->level + 1;
2459         rc->backref_cache.path[node->level] = node;
2460         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2461                 cond_resched();
2462
2463                 upper = edge->node[UPPER];
2464                 root = select_reloc_root(trans, rc, upper, edges, &nr);
2465                 BUG_ON(!root);
2466
2467                 if (upper->eb && !upper->locked) {
2468                         if (!lowest) {
2469                                 ret = btrfs_bin_search(upper->eb, key,
2470                                                        upper->level, &slot);
2471                                 BUG_ON(ret);
2472                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2473                                 if (node->eb->start == bytenr)
2474                                         goto next;
2475                         }
2476                         drop_node_buffer(upper);
2477                 }
2478
2479                 if (!upper->eb) {
2480                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2481                         if (ret < 0) {
2482                                 err = ret;
2483                                 break;
2484                         }
2485                         BUG_ON(ret > 0);
2486
2487                         if (!upper->eb) {
2488                                 upper->eb = path->nodes[upper->level];
2489                                 path->nodes[upper->level] = NULL;
2490                         } else {
2491                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2492                         }
2493
2494                         upper->locked = 1;
2495                         path->locks[upper->level] = 0;
2496
2497                         slot = path->slots[upper->level];
2498                         btrfs_release_path(NULL, path);
2499                 } else {
2500                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2501                                                &slot);
2502                         BUG_ON(ret);
2503                 }
2504
2505                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2506                 if (lowest) {
2507                         BUG_ON(bytenr != node->bytenr);
2508                 } else {
2509                         if (node->eb->start == bytenr)
2510                                 goto next;
2511                 }
2512
2513                 blocksize = btrfs_level_size(root, node->level);
2514                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2515                 eb = read_tree_block(root, bytenr, blocksize, generation);
2516                 btrfs_tree_lock(eb);
2517                 btrfs_set_lock_blocking(eb);
2518
2519                 if (!node->eb) {
2520                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2521                                               slot, &eb);
2522                         btrfs_tree_unlock(eb);
2523                         free_extent_buffer(eb);
2524                         if (ret < 0) {
2525                                 err = ret;
2526                                 goto next;
2527                         }
2528                         BUG_ON(node->eb != eb);
2529                 } else {
2530                         btrfs_set_node_blockptr(upper->eb, slot,
2531                                                 node->eb->start);
2532                         btrfs_set_node_ptr_generation(upper->eb, slot,
2533                                                       trans->transid);
2534                         btrfs_mark_buffer_dirty(upper->eb);
2535
2536                         ret = btrfs_inc_extent_ref(trans, root,
2537                                                 node->eb->start, blocksize,
2538                                                 upper->eb->start,
2539                                                 btrfs_header_owner(upper->eb),
2540                                                 node->level, 0);
2541                         BUG_ON(ret);
2542
2543                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2544                         BUG_ON(ret);
2545                 }
2546 next:
2547                 if (!upper->pending)
2548                         drop_node_buffer(upper);
2549                 else
2550                         unlock_node_buffer(upper);
2551                 if (err)
2552                         break;
2553         }
2554
2555         if (!err && node->pending) {
2556                 drop_node_buffer(node);
2557                 list_move_tail(&node->list, &rc->backref_cache.changed);
2558                 node->pending = 0;
2559         }
2560
2561         path->lowest_level = 0;
2562         BUG_ON(err == -ENOSPC);
2563         return err;
2564 }
2565
2566 static int link_to_upper(struct btrfs_trans_handle *trans,
2567                          struct reloc_control *rc,
2568                          struct backref_node *node,
2569                          struct btrfs_path *path)
2570 {
2571         struct btrfs_key key;
2572
2573         btrfs_node_key_to_cpu(node->eb, &key, 0);
2574         return do_relocation(trans, rc, node, &key, path, 0);
2575 }
2576
2577 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2578                                 struct reloc_control *rc,
2579                                 struct btrfs_path *path, int err)
2580 {
2581         LIST_HEAD(list);
2582         struct backref_cache *cache = &rc->backref_cache;
2583         struct backref_node *node;
2584         int level;
2585         int ret;
2586
2587         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2588                 while (!list_empty(&cache->pending[level])) {
2589                         node = list_entry(cache->pending[level].next,
2590                                           struct backref_node, list);
2591                         list_move_tail(&node->list, &list);
2592                         BUG_ON(!node->pending);
2593
2594                         if (!err) {
2595                                 ret = link_to_upper(trans, rc, node, path);
2596                                 if (ret < 0)
2597                                         err = ret;
2598                         }
2599                 }
2600                 list_splice_init(&list, &cache->pending[level]);
2601         }
2602         return err;
2603 }
2604
2605 static void mark_block_processed(struct reloc_control *rc,
2606                                  u64 bytenr, u32 blocksize)
2607 {
2608         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2609                         EXTENT_DIRTY, GFP_NOFS);
2610 }
2611
2612 static void __mark_block_processed(struct reloc_control *rc,
2613                                    struct backref_node *node)
2614 {
2615         u32 blocksize;
2616         if (node->level == 0 ||
2617             in_block_group(node->bytenr, rc->block_group)) {
2618                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2619                 mark_block_processed(rc, node->bytenr, blocksize);
2620         }
2621         node->processed = 1;
2622 }
2623
2624 /*
2625  * mark a block and all blocks directly/indirectly reference the block
2626  * as processed.
2627  */
2628 static void update_processed_blocks(struct reloc_control *rc,
2629                                     struct backref_node *node)
2630 {
2631         struct backref_node *next = node;
2632         struct backref_edge *edge;
2633         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2634         int index = 0;
2635
2636         while (next) {
2637                 cond_resched();
2638                 while (1) {
2639                         if (next->processed)
2640                                 break;
2641
2642                         __mark_block_processed(rc, next);
2643
2644                         if (list_empty(&next->upper))
2645                                 break;
2646
2647                         edge = list_entry(next->upper.next,
2648                                           struct backref_edge, list[LOWER]);
2649                         edges[index++] = edge;
2650                         next = edge->node[UPPER];
2651                 }
2652                 next = walk_down_backref(edges, &index);
2653         }
2654 }
2655
2656 static int tree_block_processed(u64 bytenr, u32 blocksize,
2657                                 struct reloc_control *rc)
2658 {
2659         if (test_range_bit(&rc->processed_blocks, bytenr,
2660                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2661                 return 1;
2662         return 0;
2663 }
2664
2665 static int get_tree_block_key(struct reloc_control *rc,
2666                               struct tree_block *block)
2667 {
2668         struct extent_buffer *eb;
2669
2670         BUG_ON(block->key_ready);
2671         eb = read_tree_block(rc->extent_root, block->bytenr,
2672                              block->key.objectid, block->key.offset);
2673         WARN_ON(btrfs_header_level(eb) != block->level);
2674         if (block->level == 0)
2675                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2676         else
2677                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2678         free_extent_buffer(eb);
2679         block->key_ready = 1;
2680         return 0;
2681 }
2682
2683 static int reada_tree_block(struct reloc_control *rc,
2684                             struct tree_block *block)
2685 {
2686         BUG_ON(block->key_ready);
2687         readahead_tree_block(rc->extent_root, block->bytenr,
2688                              block->key.objectid, block->key.offset);
2689         return 0;
2690 }
2691
2692 /*
2693  * helper function to relocate a tree block
2694  */
2695 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2696                                 struct reloc_control *rc,
2697                                 struct backref_node *node,
2698                                 struct btrfs_key *key,
2699                                 struct btrfs_path *path)
2700 {
2701         struct btrfs_root *root;
2702         int release = 0;
2703         int ret = 0;
2704
2705         if (!node)
2706                 return 0;
2707
2708         BUG_ON(node->processed);
2709         root = select_one_root(trans, node);
2710         if (root == ERR_PTR(-ENOENT)) {
2711                 update_processed_blocks(rc, node);
2712                 goto out;
2713         }
2714
2715         if (!root || root->ref_cows) {
2716                 ret = reserve_metadata_space(trans, rc, node);
2717                 if (ret)
2718                         goto out;
2719                 release = 1;
2720         }
2721
2722         if (root) {
2723                 if (root->ref_cows) {
2724                         BUG_ON(node->new_bytenr);
2725                         BUG_ON(!list_empty(&node->list));
2726                         btrfs_record_root_in_trans(trans, root);
2727                         root = root->reloc_root;
2728                         node->new_bytenr = root->node->start;
2729                         node->root = root;
2730                         list_add_tail(&node->list, &rc->backref_cache.changed);
2731                 } else {
2732                         path->lowest_level = node->level;
2733                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2734                         btrfs_release_path(root, path);
2735                         if (ret > 0)
2736                                 ret = 0;
2737                 }
2738                 if (!ret)
2739                         update_processed_blocks(rc, node);
2740         } else {
2741                 ret = do_relocation(trans, rc, node, key, path, 1);
2742         }
2743 out:
2744         if (ret || node->level == 0 || node->cowonly) {
2745                 if (release)
2746                         release_metadata_space(rc, node);
2747                 remove_backref_node(&rc->backref_cache, node);
2748         }
2749         return ret;
2750 }
2751
2752 /*
2753  * relocate a list of blocks
2754  */
2755 static noinline_for_stack
2756 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2757                          struct reloc_control *rc, struct rb_root *blocks)
2758 {
2759         struct backref_node *node;
2760         struct btrfs_path *path;
2761         struct tree_block *block;
2762         struct rb_node *rb_node;
2763         int ret;
2764         int err = 0;
2765
2766         path = btrfs_alloc_path();
2767         if (!path)
2768                 return -ENOMEM;
2769
2770         rb_node = rb_first(blocks);
2771         while (rb_node) {
2772                 block = rb_entry(rb_node, struct tree_block, rb_node);
2773                 if (!block->key_ready)
2774                         reada_tree_block(rc, block);
2775                 rb_node = rb_next(rb_node);
2776         }
2777
2778         rb_node = rb_first(blocks);
2779         while (rb_node) {
2780                 block = rb_entry(rb_node, struct tree_block, rb_node);
2781                 if (!block->key_ready)
2782                         get_tree_block_key(rc, block);
2783                 rb_node = rb_next(rb_node);
2784         }
2785
2786         rb_node = rb_first(blocks);
2787         while (rb_node) {
2788                 block = rb_entry(rb_node, struct tree_block, rb_node);
2789
2790                 node = build_backref_tree(rc, &block->key,
2791                                           block->level, block->bytenr);
2792                 if (IS_ERR(node)) {
2793                         err = PTR_ERR(node);
2794                         goto out;
2795                 }
2796
2797                 ret = relocate_tree_block(trans, rc, node, &block->key,
2798                                           path);
2799                 if (ret < 0) {
2800                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
2801                                 err = ret;
2802                         goto out;
2803                 }
2804                 rb_node = rb_next(rb_node);
2805         }
2806 out:
2807         free_block_list(blocks);
2808         err = finish_pending_nodes(trans, rc, path, err);
2809
2810         btrfs_free_path(path);
2811         return err;
2812 }
2813
2814 static noinline_for_stack
2815 int prealloc_file_extent_cluster(struct inode *inode,
2816                                  struct file_extent_cluster *cluster)
2817 {
2818         u64 alloc_hint = 0;
2819         u64 start;
2820         u64 end;
2821         u64 offset = BTRFS_I(inode)->index_cnt;
2822         u64 num_bytes;
2823         int nr = 0;
2824         int ret = 0;
2825
2826         BUG_ON(cluster->start != cluster->boundary[0]);
2827         mutex_lock(&inode->i_mutex);
2828
2829         ret = btrfs_check_data_free_space(inode, cluster->end +
2830                                           1 - cluster->start);
2831         if (ret)
2832                 goto out;
2833
2834         while (nr < cluster->nr) {
2835                 start = cluster->boundary[nr] - offset;
2836                 if (nr + 1 < cluster->nr)
2837                         end = cluster->boundary[nr + 1] - 1 - offset;
2838                 else
2839                         end = cluster->end - offset;
2840
2841                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2842                 num_bytes = end + 1 - start;
2843                 ret = btrfs_prealloc_file_range(inode, 0, start,
2844                                                 num_bytes, num_bytes,
2845                                                 end + 1, &alloc_hint);
2846                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2847                 if (ret)
2848                         break;
2849                 nr++;
2850         }
2851         btrfs_free_reserved_data_space(inode, cluster->end +
2852                                        1 - cluster->start);
2853 out:
2854         mutex_unlock(&inode->i_mutex);
2855         return ret;
2856 }
2857
2858 static noinline_for_stack
2859 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
2860                          u64 block_start)
2861 {
2862         struct btrfs_root *root = BTRFS_I(inode)->root;
2863         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2864         struct extent_map *em;
2865         int ret = 0;
2866
2867         em = alloc_extent_map(GFP_NOFS);
2868         if (!em)
2869                 return -ENOMEM;
2870
2871         em->start = start;
2872         em->len = end + 1 - start;
2873         em->block_len = em->len;
2874         em->block_start = block_start;
2875         em->bdev = root->fs_info->fs_devices->latest_bdev;
2876         set_bit(EXTENT_FLAG_PINNED, &em->flags);
2877
2878         lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2879         while (1) {
2880                 write_lock(&em_tree->lock);
2881                 ret = add_extent_mapping(em_tree, em);
2882                 write_unlock(&em_tree->lock);
2883                 if (ret != -EEXIST) {
2884                         free_extent_map(em);
2885                         break;
2886                 }
2887                 btrfs_drop_extent_cache(inode, start, end, 0);
2888         }
2889         unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2890         return ret;
2891 }
2892
2893 static int relocate_file_extent_cluster(struct inode *inode,
2894                                         struct file_extent_cluster *cluster)
2895 {
2896         u64 page_start;
2897         u64 page_end;
2898         u64 offset = BTRFS_I(inode)->index_cnt;
2899         unsigned long index;
2900         unsigned long last_index;
2901         struct page *page;
2902         struct file_ra_state *ra;
2903         int nr = 0;
2904         int ret = 0;
2905
2906         if (!cluster->nr)
2907                 return 0;
2908
2909         ra = kzalloc(sizeof(*ra), GFP_NOFS);
2910         if (!ra)
2911                 return -ENOMEM;
2912
2913         ret = prealloc_file_extent_cluster(inode, cluster);
2914         if (ret)
2915                 goto out;
2916
2917         file_ra_state_init(ra, inode->i_mapping);
2918
2919         ret = setup_extent_mapping(inode, cluster->start - offset,
2920                                    cluster->end - offset, cluster->start);
2921         if (ret)
2922                 goto out;
2923
2924         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
2925         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
2926         while (index <= last_index) {
2927                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
2928                 if (ret)
2929                         goto out;
2930
2931                 page = find_lock_page(inode->i_mapping, index);
2932                 if (!page) {
2933                         page_cache_sync_readahead(inode->i_mapping,
2934                                                   ra, NULL, index,
2935                                                   last_index + 1 - index);
2936                         page = grab_cache_page(inode->i_mapping, index);
2937                         if (!page) {
2938                                 btrfs_delalloc_release_metadata(inode,
2939                                                         PAGE_CACHE_SIZE);
2940                                 ret = -ENOMEM;
2941                                 goto out;
2942                         }
2943                 }
2944
2945                 if (PageReadahead(page)) {
2946                         page_cache_async_readahead(inode->i_mapping,
2947                                                    ra, NULL, page, index,
2948                                                    last_index + 1 - index);
2949                 }
2950
2951                 if (!PageUptodate(page)) {
2952                         btrfs_readpage(NULL, page);
2953                         lock_page(page);
2954                         if (!PageUptodate(page)) {
2955                                 unlock_page(page);
2956                                 page_cache_release(page);
2957                                 btrfs_delalloc_release_metadata(inode,
2958                                                         PAGE_CACHE_SIZE);
2959                                 ret = -EIO;
2960                                 goto out;
2961                         }
2962                 }
2963
2964                 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2965                 page_end = page_start + PAGE_CACHE_SIZE - 1;
2966
2967                 lock_extent(&BTRFS_I(inode)->io_tree,
2968                             page_start, page_end, GFP_NOFS);
2969
2970                 set_page_extent_mapped(page);
2971
2972                 if (nr < cluster->nr &&
2973                     page_start + offset == cluster->boundary[nr]) {
2974                         set_extent_bits(&BTRFS_I(inode)->io_tree,
2975                                         page_start, page_end,
2976                                         EXTENT_BOUNDARY, GFP_NOFS);
2977                         nr++;
2978                 }
2979
2980                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
2981                 set_page_dirty(page);
2982
2983                 unlock_extent(&BTRFS_I(inode)->io_tree,
2984                               page_start, page_end, GFP_NOFS);
2985                 unlock_page(page);
2986                 page_cache_release(page);
2987
2988                 index++;
2989                 balance_dirty_pages_ratelimited(inode->i_mapping);
2990                 btrfs_throttle(BTRFS_I(inode)->root);
2991         }
2992         WARN_ON(nr != cluster->nr);
2993 out:
2994         kfree(ra);
2995         return ret;
2996 }
2997
2998 static noinline_for_stack
2999 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3000                          struct file_extent_cluster *cluster)
3001 {
3002         int ret;
3003
3004         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3005                 ret = relocate_file_extent_cluster(inode, cluster);
3006                 if (ret)
3007                         return ret;
3008                 cluster->nr = 0;
3009         }
3010
3011         if (!cluster->nr)
3012                 cluster->start = extent_key->objectid;
3013         else
3014                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3015         cluster->end = extent_key->objectid + extent_key->offset - 1;
3016         cluster->boundary[cluster->nr] = extent_key->objectid;
3017         cluster->nr++;
3018
3019         if (cluster->nr >= MAX_EXTENTS) {
3020                 ret = relocate_file_extent_cluster(inode, cluster);
3021                 if (ret)
3022                         return ret;
3023                 cluster->nr = 0;
3024         }
3025         return 0;
3026 }
3027
3028 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3029 static int get_ref_objectid_v0(struct reloc_control *rc,
3030                                struct btrfs_path *path,
3031                                struct btrfs_key *extent_key,
3032                                u64 *ref_objectid, int *path_change)
3033 {
3034         struct btrfs_key key;
3035         struct extent_buffer *leaf;
3036         struct btrfs_extent_ref_v0 *ref0;
3037         int ret;
3038         int slot;
3039
3040         leaf = path->nodes[0];
3041         slot = path->slots[0];
3042         while (1) {
3043                 if (slot >= btrfs_header_nritems(leaf)) {
3044                         ret = btrfs_next_leaf(rc->extent_root, path);
3045                         if (ret < 0)
3046                                 return ret;
3047                         BUG_ON(ret > 0);
3048                         leaf = path->nodes[0];
3049                         slot = path->slots[0];
3050                         if (path_change)
3051                                 *path_change = 1;
3052                 }
3053                 btrfs_item_key_to_cpu(leaf, &key, slot);
3054                 if (key.objectid != extent_key->objectid)
3055                         return -ENOENT;
3056
3057                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3058                         slot++;
3059                         continue;
3060                 }
3061                 ref0 = btrfs_item_ptr(leaf, slot,
3062                                 struct btrfs_extent_ref_v0);
3063                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3064                 break;
3065         }
3066         return 0;
3067 }
3068 #endif
3069
3070 /*
3071  * helper to add a tree block to the list.
3072  * the major work is getting the generation and level of the block
3073  */
3074 static int add_tree_block(struct reloc_control *rc,
3075                           struct btrfs_key *extent_key,
3076                           struct btrfs_path *path,
3077                           struct rb_root *blocks)
3078 {
3079         struct extent_buffer *eb;
3080         struct btrfs_extent_item *ei;
3081         struct btrfs_tree_block_info *bi;
3082         struct tree_block *block;
3083         struct rb_node *rb_node;
3084         u32 item_size;
3085         int level = -1;
3086         int generation;
3087
3088         eb =  path->nodes[0];
3089         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3090
3091         if (item_size >= sizeof(*ei) + sizeof(*bi)) {
3092                 ei = btrfs_item_ptr(eb, path->slots[0],
3093                                 struct btrfs_extent_item);
3094                 bi = (struct btrfs_tree_block_info *)(ei + 1);
3095                 generation = btrfs_extent_generation(eb, ei);
3096                 level = btrfs_tree_block_level(eb, bi);
3097         } else {
3098 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3099                 u64 ref_owner;
3100                 int ret;
3101
3102                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3103                 ret = get_ref_objectid_v0(rc, path, extent_key,
3104                                           &ref_owner, NULL);
3105                 if (ret < 0)
3106                         return ret;
3107                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3108                 level = (int)ref_owner;
3109                 /* FIXME: get real generation */
3110                 generation = 0;
3111 #else
3112                 BUG();
3113 #endif
3114         }
3115
3116         btrfs_release_path(rc->extent_root, path);
3117
3118         BUG_ON(level == -1);
3119
3120         block = kmalloc(sizeof(*block), GFP_NOFS);
3121         if (!block)
3122                 return -ENOMEM;
3123
3124         block->bytenr = extent_key->objectid;
3125         block->key.objectid = extent_key->offset;
3126         block->key.offset = generation;
3127         block->level = level;
3128         block->key_ready = 0;
3129
3130         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3131         BUG_ON(rb_node);
3132
3133         return 0;
3134 }
3135
3136 /*
3137  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3138  */
3139 static int __add_tree_block(struct reloc_control *rc,
3140                             u64 bytenr, u32 blocksize,
3141                             struct rb_root *blocks)
3142 {
3143         struct btrfs_path *path;
3144         struct btrfs_key key;
3145         int ret;
3146
3147         if (tree_block_processed(bytenr, blocksize, rc))
3148                 return 0;
3149
3150         if (tree_search(blocks, bytenr))
3151                 return 0;
3152
3153         path = btrfs_alloc_path();
3154         if (!path)
3155                 return -ENOMEM;
3156
3157         key.objectid = bytenr;
3158         key.type = BTRFS_EXTENT_ITEM_KEY;
3159         key.offset = blocksize;
3160
3161         path->search_commit_root = 1;
3162         path->skip_locking = 1;
3163         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3164         if (ret < 0)
3165                 goto out;
3166         BUG_ON(ret);
3167
3168         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3169         ret = add_tree_block(rc, &key, path, blocks);
3170 out:
3171         btrfs_free_path(path);
3172         return ret;
3173 }
3174
3175 /*
3176  * helper to check if the block use full backrefs for pointers in it
3177  */
3178 static int block_use_full_backref(struct reloc_control *rc,
3179                                   struct extent_buffer *eb)
3180 {
3181         u64 flags;
3182         int ret;
3183
3184         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3185             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3186                 return 1;
3187
3188         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3189                                        eb->start, eb->len, NULL, &flags);
3190         BUG_ON(ret);
3191
3192         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3193                 ret = 1;
3194         else
3195                 ret = 0;
3196         return ret;
3197 }
3198
3199 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3200                                     struct inode *inode, u64 ino)
3201 {
3202         struct btrfs_key key;
3203         struct btrfs_path *path;
3204         struct btrfs_root *root = fs_info->tree_root;
3205         struct btrfs_trans_handle *trans;
3206         unsigned long nr;
3207         int ret = 0;
3208
3209         if (inode)
3210                 goto truncate;
3211
3212         key.objectid = ino;
3213         key.type = BTRFS_INODE_ITEM_KEY;
3214         key.offset = 0;
3215
3216         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3217         if (!inode || IS_ERR(inode) || is_bad_inode(inode)) {
3218                 if (inode && !IS_ERR(inode))
3219                         iput(inode);
3220                 return -ENOENT;
3221         }
3222
3223 truncate:
3224         path = btrfs_alloc_path();
3225         if (!path) {
3226                 ret = -ENOMEM;
3227                 goto out;
3228         }
3229
3230         trans = btrfs_join_transaction(root, 0);
3231         if (IS_ERR(trans)) {
3232                 btrfs_free_path(path);
3233                 ret = PTR_ERR(trans);
3234                 goto out;
3235         }
3236
3237         ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
3238
3239         btrfs_free_path(path);
3240         nr = trans->blocks_used;
3241         btrfs_end_transaction(trans, root);
3242         btrfs_btree_balance_dirty(root, nr);
3243 out:
3244         iput(inode);
3245         return ret;
3246 }
3247
3248 /*
3249  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3250  * this function scans fs tree to find blocks reference the data extent
3251  */
3252 static int find_data_references(struct reloc_control *rc,
3253                                 struct btrfs_key *extent_key,
3254                                 struct extent_buffer *leaf,
3255                                 struct btrfs_extent_data_ref *ref,
3256                                 struct rb_root *blocks)
3257 {
3258         struct btrfs_path *path;
3259         struct tree_block *block;
3260         struct btrfs_root *root;
3261         struct btrfs_file_extent_item *fi;
3262         struct rb_node *rb_node;
3263         struct btrfs_key key;
3264         u64 ref_root;
3265         u64 ref_objectid;
3266         u64 ref_offset;
3267         u32 ref_count;
3268         u32 nritems;
3269         int err = 0;
3270         int added = 0;
3271         int counted;
3272         int ret;
3273
3274         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3275         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3276         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3277         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3278
3279         /*
3280          * This is an extent belonging to the free space cache, lets just delete
3281          * it and redo the search.
3282          */
3283         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3284                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3285                                                NULL, ref_objectid);
3286                 if (ret != -ENOENT)
3287                         return ret;
3288                 ret = 0;
3289         }
3290
3291         path = btrfs_alloc_path();
3292         if (!path)
3293                 return -ENOMEM;
3294
3295         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3296         if (IS_ERR(root)) {
3297                 err = PTR_ERR(root);
3298                 goto out;
3299         }
3300
3301         key.objectid = ref_objectid;
3302         key.offset = ref_offset;
3303         key.type = BTRFS_EXTENT_DATA_KEY;
3304
3305         path->search_commit_root = 1;
3306         path->skip_locking = 1;
3307         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3308         if (ret < 0) {
3309                 err = ret;
3310                 goto out;
3311         }
3312
3313         leaf = path->nodes[0];
3314         nritems = btrfs_header_nritems(leaf);
3315         /*
3316          * the references in tree blocks that use full backrefs
3317          * are not counted in
3318          */
3319         if (block_use_full_backref(rc, leaf))
3320                 counted = 0;
3321         else
3322                 counted = 1;
3323         rb_node = tree_search(blocks, leaf->start);
3324         if (rb_node) {
3325                 if (counted)
3326                         added = 1;
3327                 else
3328                         path->slots[0] = nritems;
3329         }
3330
3331         while (ref_count > 0) {
3332                 while (path->slots[0] >= nritems) {
3333                         ret = btrfs_next_leaf(root, path);
3334                         if (ret < 0) {
3335                                 err = ret;
3336                                 goto out;
3337                         }
3338                         if (ret > 0) {
3339                                 WARN_ON(1);
3340                                 goto out;
3341                         }
3342
3343                         leaf = path->nodes[0];
3344                         nritems = btrfs_header_nritems(leaf);
3345                         added = 0;
3346
3347                         if (block_use_full_backref(rc, leaf))
3348                                 counted = 0;
3349                         else
3350                                 counted = 1;
3351                         rb_node = tree_search(blocks, leaf->start);
3352                         if (rb_node) {
3353                                 if (counted)
3354                                         added = 1;
3355                                 else
3356                                         path->slots[0] = nritems;
3357                         }
3358                 }
3359
3360                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3361                 if (key.objectid != ref_objectid ||
3362                     key.type != BTRFS_EXTENT_DATA_KEY) {
3363                         WARN_ON(1);
3364                         break;
3365                 }
3366
3367                 fi = btrfs_item_ptr(leaf, path->slots[0],
3368                                     struct btrfs_file_extent_item);
3369
3370                 if (btrfs_file_extent_type(leaf, fi) ==
3371                     BTRFS_FILE_EXTENT_INLINE)
3372                         goto next;
3373
3374                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3375                     extent_key->objectid)
3376                         goto next;
3377
3378                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3379                 if (key.offset != ref_offset)
3380                         goto next;
3381
3382                 if (counted)
3383                         ref_count--;
3384                 if (added)
3385                         goto next;
3386
3387                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3388                         block = kmalloc(sizeof(*block), GFP_NOFS);
3389                         if (!block) {
3390                                 err = -ENOMEM;
3391                                 break;
3392                         }
3393                         block->bytenr = leaf->start;
3394                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3395                         block->level = 0;
3396                         block->key_ready = 1;
3397                         rb_node = tree_insert(blocks, block->bytenr,
3398                                               &block->rb_node);
3399                         BUG_ON(rb_node);
3400                 }
3401                 if (counted)
3402                         added = 1;
3403                 else
3404                         path->slots[0] = nritems;
3405 next:
3406                 path->slots[0]++;
3407
3408         }
3409 out:
3410         btrfs_free_path(path);
3411         return err;
3412 }
3413
3414 /*
3415  * hepler to find all tree blocks that reference a given data extent
3416  */
3417 static noinline_for_stack
3418 int add_data_references(struct reloc_control *rc,
3419                         struct btrfs_key *extent_key,
3420                         struct btrfs_path *path,
3421                         struct rb_root *blocks)
3422 {
3423         struct btrfs_key key;
3424         struct extent_buffer *eb;
3425         struct btrfs_extent_data_ref *dref;
3426         struct btrfs_extent_inline_ref *iref;
3427         unsigned long ptr;
3428         unsigned long end;
3429         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3430         int ret;
3431         int err = 0;
3432
3433         eb = path->nodes[0];
3434         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3435         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3436 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3437         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3438                 ptr = end;
3439         else
3440 #endif
3441                 ptr += sizeof(struct btrfs_extent_item);
3442
3443         while (ptr < end) {
3444                 iref = (struct btrfs_extent_inline_ref *)ptr;
3445                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3446                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3447                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3448                         ret = __add_tree_block(rc, key.offset, blocksize,
3449                                                blocks);
3450                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3451                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3452                         ret = find_data_references(rc, extent_key,
3453                                                    eb, dref, blocks);
3454                 } else {
3455                         BUG();
3456                 }
3457                 ptr += btrfs_extent_inline_ref_size(key.type);
3458         }
3459         WARN_ON(ptr > end);
3460
3461         while (1) {
3462                 cond_resched();
3463                 eb = path->nodes[0];
3464                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3465                         ret = btrfs_next_leaf(rc->extent_root, path);
3466                         if (ret < 0) {
3467                                 err = ret;
3468                                 break;
3469                         }
3470                         if (ret > 0)
3471                                 break;
3472                         eb = path->nodes[0];
3473                 }
3474
3475                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3476                 if (key.objectid != extent_key->objectid)
3477                         break;
3478
3479 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3480                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3481                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3482 #else
3483                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3484                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3485 #endif
3486                         ret = __add_tree_block(rc, key.offset, blocksize,
3487                                                blocks);
3488                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3489                         dref = btrfs_item_ptr(eb, path->slots[0],
3490                                               struct btrfs_extent_data_ref);
3491                         ret = find_data_references(rc, extent_key,
3492                                                    eb, dref, blocks);
3493                 } else {
3494                         ret = 0;
3495                 }
3496                 if (ret) {
3497                         err = ret;
3498                         break;
3499                 }
3500                 path->slots[0]++;
3501         }
3502         btrfs_release_path(rc->extent_root, path);
3503         if (err)
3504                 free_block_list(blocks);
3505         return err;
3506 }
3507
3508 /*
3509  * hepler to find next unprocessed extent
3510  */
3511 static noinline_for_stack
3512 int find_next_extent(struct btrfs_trans_handle *trans,
3513                      struct reloc_control *rc, struct btrfs_path *path,
3514                      struct btrfs_key *extent_key)
3515 {
3516         struct btrfs_key key;
3517         struct extent_buffer *leaf;
3518         u64 start, end, last;
3519         int ret;
3520
3521         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3522         while (1) {
3523                 cond_resched();
3524                 if (rc->search_start >= last) {
3525                         ret = 1;
3526                         break;
3527                 }
3528
3529                 key.objectid = rc->search_start;
3530                 key.type = BTRFS_EXTENT_ITEM_KEY;
3531                 key.offset = 0;
3532
3533                 path->search_commit_root = 1;
3534                 path->skip_locking = 1;
3535                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3536                                         0, 0);
3537                 if (ret < 0)
3538                         break;
3539 next:
3540                 leaf = path->nodes[0];
3541                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3542                         ret = btrfs_next_leaf(rc->extent_root, path);
3543                         if (ret != 0)
3544                                 break;
3545                         leaf = path->nodes[0];
3546                 }
3547
3548                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3549                 if (key.objectid >= last) {
3550                         ret = 1;
3551                         break;
3552                 }
3553
3554                 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3555                     key.objectid + key.offset <= rc->search_start) {
3556                         path->slots[0]++;
3557                         goto next;
3558                 }
3559
3560                 ret = find_first_extent_bit(&rc->processed_blocks,
3561                                             key.objectid, &start, &end,
3562                                             EXTENT_DIRTY);
3563
3564                 if (ret == 0 && start <= key.objectid) {
3565                         btrfs_release_path(rc->extent_root, path);
3566                         rc->search_start = end + 1;
3567                 } else {
3568                         rc->search_start = key.objectid + key.offset;
3569                         memcpy(extent_key, &key, sizeof(key));
3570                         return 0;
3571                 }
3572         }
3573         btrfs_release_path(rc->extent_root, path);
3574         return ret;
3575 }
3576
3577 static void set_reloc_control(struct reloc_control *rc)
3578 {
3579         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3580         mutex_lock(&fs_info->trans_mutex);
3581         fs_info->reloc_ctl = rc;
3582         mutex_unlock(&fs_info->trans_mutex);
3583 }
3584
3585 static void unset_reloc_control(struct reloc_control *rc)
3586 {
3587         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3588         mutex_lock(&fs_info->trans_mutex);
3589         fs_info->reloc_ctl = NULL;
3590         mutex_unlock(&fs_info->trans_mutex);
3591 }
3592
3593 static int check_extent_flags(u64 flags)
3594 {
3595         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3596             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3597                 return 1;
3598         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3599             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3600                 return 1;
3601         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3602             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3603                 return 1;
3604         return 0;
3605 }
3606
3607 static noinline_for_stack
3608 int prepare_to_relocate(struct reloc_control *rc)
3609 {
3610         struct btrfs_trans_handle *trans;
3611         int ret;
3612
3613         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root);
3614         if (!rc->block_rsv)
3615                 return -ENOMEM;
3616
3617         /*
3618          * reserve some space for creating reloc trees.
3619          * btrfs_init_reloc_root will use them when there
3620          * is no reservation in transaction handle.
3621          */
3622         ret = btrfs_block_rsv_add(NULL, rc->extent_root, rc->block_rsv,
3623                                   rc->extent_root->nodesize * 256);
3624         if (ret)
3625                 return ret;
3626
3627         rc->block_rsv->refill_used = 1;
3628         btrfs_add_durable_block_rsv(rc->extent_root->fs_info, rc->block_rsv);
3629
3630         memset(&rc->cluster, 0, sizeof(rc->cluster));
3631         rc->search_start = rc->block_group->key.objectid;
3632         rc->extents_found = 0;
3633         rc->nodes_relocated = 0;
3634         rc->merging_rsv_size = 0;
3635
3636         rc->create_reloc_tree = 1;
3637         set_reloc_control(rc);
3638
3639         trans = btrfs_join_transaction(rc->extent_root, 1);
3640         BUG_ON(IS_ERR(trans));
3641         btrfs_commit_transaction(trans, rc->extent_root);
3642         return 0;
3643 }
3644
3645 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3646 {
3647         struct rb_root blocks = RB_ROOT;
3648         struct btrfs_key key;
3649         struct btrfs_trans_handle *trans = NULL;
3650         struct btrfs_path *path;
3651         struct btrfs_extent_item *ei;
3652         unsigned long nr;
3653         u64 flags;
3654         u32 item_size;
3655         int ret;
3656         int err = 0;
3657
3658         path = btrfs_alloc_path();
3659         if (!path)
3660                 return -ENOMEM;
3661
3662         ret = prepare_to_relocate(rc);
3663         if (ret) {
3664                 err = ret;
3665                 goto out_free;
3666         }
3667
3668         while (1) {
3669                 trans = btrfs_start_transaction(rc->extent_root, 0);
3670                 BUG_ON(IS_ERR(trans));
3671
3672                 if (update_backref_cache(trans, &rc->backref_cache)) {
3673                         btrfs_end_transaction(trans, rc->extent_root);
3674                         continue;
3675                 }
3676
3677                 ret = find_next_extent(trans, rc, path, &key);
3678                 if (ret < 0)
3679                         err = ret;
3680                 if (ret != 0)
3681                         break;
3682
3683                 rc->extents_found++;
3684
3685                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3686                                     struct btrfs_extent_item);
3687                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3688                 if (item_size >= sizeof(*ei)) {
3689                         flags = btrfs_extent_flags(path->nodes[0], ei);
3690                         ret = check_extent_flags(flags);
3691                         BUG_ON(ret);
3692
3693                 } else {
3694 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3695                         u64 ref_owner;
3696                         int path_change = 0;
3697
3698                         BUG_ON(item_size !=
3699                                sizeof(struct btrfs_extent_item_v0));
3700                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3701                                                   &path_change);
3702                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3703                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3704                         else
3705                                 flags = BTRFS_EXTENT_FLAG_DATA;
3706
3707                         if (path_change) {
3708                                 btrfs_release_path(rc->extent_root, path);
3709
3710                                 path->search_commit_root = 1;
3711                                 path->skip_locking = 1;
3712                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3713                                                         &key, path, 0, 0);
3714                                 if (ret < 0) {
3715                                         err = ret;
3716                                         break;
3717                                 }
3718                                 BUG_ON(ret > 0);
3719                         }
3720 #else
3721                         BUG();
3722 #endif
3723                 }
3724
3725                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3726                         ret = add_tree_block(rc, &key, path, &blocks);
3727                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3728                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
3729                         ret = add_data_references(rc, &key, path, &blocks);
3730                 } else {
3731                         btrfs_release_path(rc->extent_root, path);
3732                         ret = 0;
3733                 }
3734                 if (ret < 0) {
3735                         err = ret;
3736                         break;
3737                 }
3738
3739                 if (!RB_EMPTY_ROOT(&blocks)) {
3740                         ret = relocate_tree_blocks(trans, rc, &blocks);
3741                         if (ret < 0) {
3742                                 if (ret != -EAGAIN) {
3743                                         err = ret;
3744                                         break;
3745                                 }
3746                                 rc->extents_found--;
3747                                 rc->search_start = key.objectid;
3748                         }
3749                 }
3750
3751                 ret = btrfs_block_rsv_check(trans, rc->extent_root,
3752                                             rc->block_rsv, 0, 5);
3753                 if (ret < 0) {
3754                         if (ret != -EAGAIN) {
3755                                 err = ret;
3756                                 WARN_ON(1);
3757                                 break;
3758                         }
3759                         rc->commit_transaction = 1;
3760                 }
3761
3762                 if (rc->commit_transaction) {
3763                         rc->commit_transaction = 0;
3764                         ret = btrfs_commit_transaction(trans, rc->extent_root);
3765                         BUG_ON(ret);
3766                 } else {
3767                         nr = trans->blocks_used;
3768                         btrfs_end_transaction_throttle(trans, rc->extent_root);
3769                         btrfs_btree_balance_dirty(rc->extent_root, nr);
3770                 }
3771                 trans = NULL;
3772
3773                 if (rc->stage == MOVE_DATA_EXTENTS &&
3774                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
3775                         rc->found_file_extent = 1;
3776                         ret = relocate_data_extent(rc->data_inode,
3777                                                    &key, &rc->cluster);
3778                         if (ret < 0) {
3779                                 err = ret;
3780                                 break;
3781                         }
3782                 }
3783         }
3784
3785         btrfs_release_path(rc->extent_root, path);
3786         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3787                           GFP_NOFS);
3788
3789         if (trans) {
3790                 nr = trans->blocks_used;
3791                 btrfs_end_transaction_throttle(trans, rc->extent_root);
3792                 btrfs_btree_balance_dirty(rc->extent_root, nr);
3793         }
3794
3795         if (!err) {
3796                 ret = relocate_file_extent_cluster(rc->data_inode,
3797                                                    &rc->cluster);
3798                 if (ret < 0)
3799                         err = ret;
3800         }
3801
3802         rc->create_reloc_tree = 0;
3803         set_reloc_control(rc);
3804
3805         backref_cache_cleanup(&rc->backref_cache);
3806         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3807
3808         err = prepare_to_merge(rc, err);
3809
3810         merge_reloc_roots(rc);
3811
3812         rc->merge_reloc_tree = 0;
3813         unset_reloc_control(rc);
3814         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3815
3816         /* get rid of pinned extents */
3817         trans = btrfs_join_transaction(rc->extent_root, 1);
3818         if (IS_ERR(trans))
3819                 err = PTR_ERR(trans);
3820         else
3821                 btrfs_commit_transaction(trans, rc->extent_root);
3822 out_free:
3823         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
3824         btrfs_free_path(path);
3825         return err;
3826 }
3827
3828 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3829                                  struct btrfs_root *root, u64 objectid)
3830 {
3831         struct btrfs_path *path;
3832         struct btrfs_inode_item *item;
3833         struct extent_buffer *leaf;
3834         int ret;
3835
3836         path = btrfs_alloc_path();
3837         if (!path)
3838                 return -ENOMEM;
3839
3840         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3841         if (ret)
3842                 goto out;
3843
3844         leaf = path->nodes[0];
3845         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3846         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3847         btrfs_set_inode_generation(leaf, item, 1);
3848         btrfs_set_inode_size(leaf, item, 0);
3849         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3850         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
3851                                           BTRFS_INODE_PREALLOC);
3852         btrfs_mark_buffer_dirty(leaf);
3853         btrfs_release_path(root, path);
3854 out:
3855         btrfs_free_path(path);
3856         return ret;
3857 }
3858
3859 /*
3860  * helper to create inode for data relocation.
3861  * the inode is in data relocation tree and its link count is 0
3862  */
3863 static noinline_for_stack
3864 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3865                                  struct btrfs_block_group_cache *group)
3866 {
3867         struct inode *inode = NULL;
3868         struct btrfs_trans_handle *trans;
3869         struct btrfs_root *root;
3870         struct btrfs_key key;
3871         unsigned long nr;
3872         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3873         int err = 0;
3874
3875         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3876         if (IS_ERR(root))
3877                 return ERR_CAST(root);
3878
3879         trans = btrfs_start_transaction(root, 6);
3880         if (IS_ERR(trans))
3881                 return ERR_CAST(trans);
3882
3883         err = btrfs_find_free_objectid(trans, root, objectid, &objectid);
3884         if (err)
3885                 goto out;
3886
3887         err = __insert_orphan_inode(trans, root, objectid);
3888         BUG_ON(err);
3889
3890         key.objectid = objectid;
3891         key.type = BTRFS_INODE_ITEM_KEY;
3892         key.offset = 0;
3893         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
3894         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3895         BTRFS_I(inode)->index_cnt = group->key.objectid;
3896
3897         err = btrfs_orphan_add(trans, inode);
3898 out:
3899         nr = trans->blocks_used;
3900         btrfs_end_transaction(trans, root);
3901         btrfs_btree_balance_dirty(root, nr);
3902         if (err) {
3903                 if (inode)
3904                         iput(inode);
3905                 inode = ERR_PTR(err);
3906         }
3907         return inode;
3908 }
3909
3910 static struct reloc_control *alloc_reloc_control(void)
3911 {
3912         struct reloc_control *rc;
3913
3914         rc = kzalloc(sizeof(*rc), GFP_NOFS);
3915         if (!rc)
3916                 return NULL;
3917
3918         INIT_LIST_HEAD(&rc->reloc_roots);
3919         backref_cache_init(&rc->backref_cache);
3920         mapping_tree_init(&rc->reloc_root_tree);
3921         extent_io_tree_init(&rc->processed_blocks, NULL, GFP_NOFS);
3922         return rc;
3923 }
3924
3925 /*
3926  * function to relocate all extents in a block group.
3927  */
3928 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
3929 {
3930         struct btrfs_fs_info *fs_info = extent_root->fs_info;
3931         struct reloc_control *rc;
3932         struct inode *inode;
3933         struct btrfs_path *path;
3934         int ret;
3935         int rw = 0;
3936         int err = 0;
3937
3938         rc = alloc_reloc_control();
3939         if (!rc)
3940                 return -ENOMEM;
3941
3942         rc->extent_root = extent_root;
3943
3944         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
3945         BUG_ON(!rc->block_group);
3946
3947         if (!rc->block_group->ro) {
3948                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
3949                 if (ret) {
3950                         err = ret;
3951                         goto out;
3952                 }
3953                 rw = 1;
3954         }
3955
3956         path = btrfs_alloc_path();
3957         if (!path) {
3958                 err = -ENOMEM;
3959                 goto out;
3960         }
3961
3962         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
3963                                         path);
3964         btrfs_free_path(path);
3965
3966         if (!IS_ERR(inode))
3967                 ret = delete_block_group_cache(fs_info, inode, 0);
3968         else
3969                 ret = PTR_ERR(inode);
3970
3971         if (ret && ret != -ENOENT) {
3972                 err = ret;
3973                 goto out;
3974         }
3975
3976         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
3977         if (IS_ERR(rc->data_inode)) {
3978                 err = PTR_ERR(rc->data_inode);
3979                 rc->data_inode = NULL;
3980                 goto out;
3981         }
3982
3983         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
3984                (unsigned long long)rc->block_group->key.objectid,
3985                (unsigned long long)rc->block_group->flags);
3986
3987         btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
3988         btrfs_wait_ordered_extents(fs_info->tree_root, 0, 0);
3989
3990         while (1) {
3991                 mutex_lock(&fs_info->cleaner_mutex);
3992
3993                 btrfs_clean_old_snapshots(fs_info->tree_root);
3994                 ret = relocate_block_group(rc);
3995
3996                 mutex_unlock(&fs_info->cleaner_mutex);
3997                 if (ret < 0) {
3998                         err = ret;
3999                         goto out;
4000                 }
4001
4002                 if (rc->extents_found == 0)
4003                         break;
4004
4005                 printk(KERN_INFO "btrfs: found %llu extents\n",
4006                         (unsigned long long)rc->extents_found);
4007
4008                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4009                         btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
4010                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4011                                                  0, -1);
4012                         rc->stage = UPDATE_DATA_PTRS;
4013                 }
4014         }
4015
4016         filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4017                                      rc->block_group->key.objectid,
4018                                      rc->block_group->key.objectid +
4019                                      rc->block_group->key.offset - 1);
4020
4021         WARN_ON(rc->block_group->pinned > 0);
4022         WARN_ON(rc->block_group->reserved > 0);
4023         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4024 out:
4025         if (err && rw)
4026                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4027         iput(rc->data_inode);
4028         btrfs_put_block_group(rc->block_group);
4029         kfree(rc);
4030         return err;
4031 }
4032
4033 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4034 {
4035         struct btrfs_trans_handle *trans;
4036         int ret;
4037
4038         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4039         BUG_ON(IS_ERR(trans));
4040
4041         memset(&root->root_item.drop_progress, 0,
4042                 sizeof(root->root_item.drop_progress));
4043         root->root_item.drop_level = 0;
4044         btrfs_set_root_refs(&root->root_item, 0);
4045         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4046                                 &root->root_key, &root->root_item);
4047         BUG_ON(ret);
4048
4049         ret = btrfs_end_transaction(trans, root->fs_info->tree_root);
4050         BUG_ON(ret);
4051         return 0;
4052 }
4053
4054 /*
4055  * recover relocation interrupted by system crash.
4056  *
4057  * this function resumes merging reloc trees with corresponding fs trees.
4058  * this is important for keeping the sharing of tree blocks
4059  */
4060 int btrfs_recover_relocation(struct btrfs_root *root)
4061 {
4062         LIST_HEAD(reloc_roots);
4063         struct btrfs_key key;
4064         struct btrfs_root *fs_root;
4065         struct btrfs_root *reloc_root;
4066         struct btrfs_path *path;
4067         struct extent_buffer *leaf;
4068         struct reloc_control *rc = NULL;
4069         struct btrfs_trans_handle *trans;
4070         int ret;
4071         int err = 0;
4072
4073         path = btrfs_alloc_path();
4074         if (!path)
4075                 return -ENOMEM;
4076
4077         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4078         key.type = BTRFS_ROOT_ITEM_KEY;
4079         key.offset = (u64)-1;
4080
4081         while (1) {
4082                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4083                                         path, 0, 0);
4084                 if (ret < 0) {
4085                         err = ret;
4086                         goto out;
4087                 }
4088                 if (ret > 0) {
4089                         if (path->slots[0] == 0)
4090                                 break;
4091                         path->slots[0]--;
4092                 }
4093                 leaf = path->nodes[0];
4094                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4095                 btrfs_release_path(root->fs_info->tree_root, path);
4096
4097                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4098                     key.type != BTRFS_ROOT_ITEM_KEY)
4099                         break;
4100
4101                 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
4102                 if (IS_ERR(reloc_root)) {
4103                         err = PTR_ERR(reloc_root);
4104                         goto out;
4105                 }
4106
4107                 list_add(&reloc_root->root_list, &reloc_roots);
4108
4109                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4110                         fs_root = read_fs_root(root->fs_info,
4111                                                reloc_root->root_key.offset);
4112                         if (IS_ERR(fs_root)) {
4113                                 ret = PTR_ERR(fs_root);
4114                                 if (ret != -ENOENT) {
4115                                         err = ret;
4116                                         goto out;
4117                                 }
4118                                 mark_garbage_root(reloc_root);
4119                         }
4120                 }
4121
4122                 if (key.offset == 0)
4123                         break;
4124
4125                 key.offset--;
4126         }
4127         btrfs_release_path(root->fs_info->tree_root, path);
4128
4129         if (list_empty(&reloc_roots))
4130                 goto out;
4131
4132         rc = alloc_reloc_control();
4133         if (!rc) {
4134                 err = -ENOMEM;
4135                 goto out;
4136         }
4137
4138         rc->extent_root = root->fs_info->extent_root;
4139
4140         set_reloc_control(rc);
4141
4142         trans = btrfs_join_transaction(rc->extent_root, 1);
4143         if (IS_ERR(trans)) {
4144                 unset_reloc_control(rc);
4145                 err = PTR_ERR(trans);
4146                 goto out_free;
4147         }
4148
4149         rc->merge_reloc_tree = 1;
4150
4151         while (!list_empty(&reloc_roots)) {
4152                 reloc_root = list_entry(reloc_roots.next,
4153                                         struct btrfs_root, root_list);
4154                 list_del(&reloc_root->root_list);
4155
4156                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4157                         list_add_tail(&reloc_root->root_list,
4158                                       &rc->reloc_roots);
4159                         continue;
4160                 }
4161
4162                 fs_root = read_fs_root(root->fs_info,
4163                                        reloc_root->root_key.offset);
4164                 BUG_ON(IS_ERR(fs_root));
4165
4166                 __add_reloc_root(reloc_root);
4167                 fs_root->reloc_root = reloc_root;
4168         }
4169
4170         btrfs_commit_transaction(trans, rc->extent_root);
4171
4172         merge_reloc_roots(rc);
4173
4174         unset_reloc_control(rc);
4175
4176         trans = btrfs_join_transaction(rc->extent_root, 1);
4177         if (IS_ERR(trans))
4178                 err = PTR_ERR(trans);
4179         else
4180                 btrfs_commit_transaction(trans, rc->extent_root);
4181 out_free:
4182         kfree(rc);
4183 out:
4184         while (!list_empty(&reloc_roots)) {
4185                 reloc_root = list_entry(reloc_roots.next,
4186                                         struct btrfs_root, root_list);
4187                 list_del(&reloc_root->root_list);
4188                 free_extent_buffer(reloc_root->node);
4189                 free_extent_buffer(reloc_root->commit_root);
4190                 kfree(reloc_root);
4191         }
4192         btrfs_free_path(path);
4193
4194         if (err == 0) {
4195                 /* cleanup orphan inode in data relocation tree */
4196                 fs_root = read_fs_root(root->fs_info,
4197                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4198                 if (IS_ERR(fs_root))
4199                         err = PTR_ERR(fs_root);
4200                 else
4201                         btrfs_orphan_cleanup(fs_root);
4202         }
4203         return err;
4204 }
4205
4206 /*
4207  * helper to add ordered checksum for data relocation.
4208  *
4209  * cloning checksum properly handles the nodatasum extents.
4210  * it also saves CPU time to re-calculate the checksum.
4211  */
4212 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4213 {
4214         struct btrfs_ordered_sum *sums;
4215         struct btrfs_sector_sum *sector_sum;
4216         struct btrfs_ordered_extent *ordered;
4217         struct btrfs_root *root = BTRFS_I(inode)->root;
4218         size_t offset;
4219         int ret;
4220         u64 disk_bytenr;
4221         LIST_HEAD(list);
4222
4223         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4224         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4225
4226         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4227         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4228                                        disk_bytenr + len - 1, &list);
4229
4230         while (!list_empty(&list)) {
4231                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4232                 list_del_init(&sums->list);
4233
4234                 sector_sum = sums->sums;
4235                 sums->bytenr = ordered->start;
4236
4237                 offset = 0;
4238                 while (offset < sums->len) {
4239                         sector_sum->bytenr += ordered->start - disk_bytenr;
4240                         sector_sum++;
4241                         offset += root->sectorsize;
4242                 }
4243
4244                 btrfs_add_ordered_sum(inode, ordered, sums);
4245         }
4246         btrfs_put_ordered_extent(ordered);
4247         return ret;
4248 }
4249
4250 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4251                            struct btrfs_root *root, struct extent_buffer *buf,
4252                            struct extent_buffer *cow)
4253 {
4254         struct reloc_control *rc;
4255         struct backref_node *node;
4256         int first_cow = 0;
4257         int level;
4258         int ret;
4259
4260         rc = root->fs_info->reloc_ctl;
4261         if (!rc)
4262                 return;
4263
4264         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4265                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4266
4267         level = btrfs_header_level(buf);
4268         if (btrfs_header_generation(buf) <=
4269             btrfs_root_last_snapshot(&root->root_item))
4270                 first_cow = 1;
4271
4272         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4273             rc->create_reloc_tree) {
4274                 WARN_ON(!first_cow && level == 0);
4275
4276                 node = rc->backref_cache.path[level];
4277                 BUG_ON(node->bytenr != buf->start &&
4278                        node->new_bytenr != buf->start);
4279
4280                 drop_node_buffer(node);
4281                 extent_buffer_get(cow);
4282                 node->eb = cow;
4283                 node->new_bytenr = cow->start;
4284
4285                 if (!node->pending) {
4286                         list_move_tail(&node->list,
4287                                        &rc->backref_cache.pending[level]);
4288                         node->pending = 1;
4289                 }
4290
4291                 if (first_cow)
4292                         __mark_block_processed(rc, node);
4293
4294                 if (first_cow && level > 0)
4295                         rc->nodes_relocated += buf->len;
4296         }
4297
4298         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4299                 ret = replace_file_extents(trans, rc, root, cow);
4300                 BUG_ON(ret);
4301         }
4302 }
4303
4304 /*
4305  * called before creating snapshot. it calculates metadata reservation
4306  * requried for relocating tree blocks in the snapshot
4307  */
4308 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4309                               struct btrfs_pending_snapshot *pending,
4310                               u64 *bytes_to_reserve)
4311 {
4312         struct btrfs_root *root;
4313         struct reloc_control *rc;
4314
4315         root = pending->root;
4316         if (!root->reloc_root)
4317                 return;
4318
4319         rc = root->fs_info->reloc_ctl;
4320         if (!rc->merge_reloc_tree)
4321                 return;
4322
4323         root = root->reloc_root;
4324         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4325         /*
4326          * relocation is in the stage of merging trees. the space
4327          * used by merging a reloc tree is twice the size of
4328          * relocated tree nodes in the worst case. half for cowing
4329          * the reloc tree, half for cowing the fs tree. the space
4330          * used by cowing the reloc tree will be freed after the
4331          * tree is dropped. if we create snapshot, cowing the fs
4332          * tree may use more space than it frees. so we need
4333          * reserve extra space.
4334          */
4335         *bytes_to_reserve += rc->nodes_relocated;
4336 }
4337
4338 /*
4339  * called after snapshot is created. migrate block reservation
4340  * and create reloc root for the newly created snapshot
4341  */
4342 void btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4343                                struct btrfs_pending_snapshot *pending)
4344 {
4345         struct btrfs_root *root = pending->root;
4346         struct btrfs_root *reloc_root;
4347         struct btrfs_root *new_root;
4348         struct reloc_control *rc;
4349         int ret;
4350
4351         if (!root->reloc_root)
4352                 return;
4353
4354         rc = root->fs_info->reloc_ctl;
4355         rc->merging_rsv_size += rc->nodes_relocated;
4356
4357         if (rc->merge_reloc_tree) {
4358                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4359                                               rc->block_rsv,
4360                                               rc->nodes_relocated);
4361                 BUG_ON(ret);
4362         }
4363
4364         new_root = pending->snap;
4365         reloc_root = create_reloc_root(trans, root->reloc_root,
4366                                        new_root->root_key.objectid);
4367
4368         __add_reloc_root(reloc_root);
4369         new_root->reloc_root = reloc_root;
4370
4371         if (rc->create_reloc_tree) {
4372                 ret = clone_backref_node(trans, rc, root, reloc_root);
4373                 BUG_ON(ret);
4374         }
4375 }