btrfs: get fs_info from block group in lookup_free_space_inode
[sfrench/cifs-2.6.git] / fs / btrfs / relocation.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2009 Oracle.  All rights reserved.
4  */
5
6 #include <linux/sched.h>
7 #include <linux/pagemap.h>
8 #include <linux/writeback.h>
9 #include <linux/blkdev.h>
10 #include <linux/rbtree.h>
11 #include <linux/slab.h>
12 #include "ctree.h"
13 #include "disk-io.h"
14 #include "transaction.h"
15 #include "volumes.h"
16 #include "locking.h"
17 #include "btrfs_inode.h"
18 #include "async-thread.h"
19 #include "free-space-cache.h"
20 #include "inode-map.h"
21 #include "qgroup.h"
22 #include "print-tree.h"
23
24 /*
25  * backref_node, mapping_node and tree_block start with this
26  */
27 struct tree_entry {
28         struct rb_node rb_node;
29         u64 bytenr;
30 };
31
32 /*
33  * present a tree block in the backref cache
34  */
35 struct backref_node {
36         struct rb_node rb_node;
37         u64 bytenr;
38
39         u64 new_bytenr;
40         /* objectid of tree block owner, can be not uptodate */
41         u64 owner;
42         /* link to pending, changed or detached list */
43         struct list_head list;
44         /* list of upper level blocks reference this block */
45         struct list_head upper;
46         /* list of child blocks in the cache */
47         struct list_head lower;
48         /* NULL if this node is not tree root */
49         struct btrfs_root *root;
50         /* extent buffer got by COW the block */
51         struct extent_buffer *eb;
52         /* level of tree block */
53         unsigned int level:8;
54         /* is the block in non-reference counted tree */
55         unsigned int cowonly:1;
56         /* 1 if no child node in the cache */
57         unsigned int lowest:1;
58         /* is the extent buffer locked */
59         unsigned int locked:1;
60         /* has the block been processed */
61         unsigned int processed:1;
62         /* have backrefs of this block been checked */
63         unsigned int checked:1;
64         /*
65          * 1 if corresponding block has been cowed but some upper
66          * level block pointers may not point to the new location
67          */
68         unsigned int pending:1;
69         /*
70          * 1 if the backref node isn't connected to any other
71          * backref node.
72          */
73         unsigned int detached:1;
74 };
75
76 /*
77  * present a block pointer in the backref cache
78  */
79 struct backref_edge {
80         struct list_head list[2];
81         struct backref_node *node[2];
82 };
83
84 #define LOWER   0
85 #define UPPER   1
86 #define RELOCATION_RESERVED_NODES       256
87
88 struct backref_cache {
89         /* red black tree of all backref nodes in the cache */
90         struct rb_root rb_root;
91         /* for passing backref nodes to btrfs_reloc_cow_block */
92         struct backref_node *path[BTRFS_MAX_LEVEL];
93         /*
94          * list of blocks that have been cowed but some block
95          * pointers in upper level blocks may not reflect the
96          * new location
97          */
98         struct list_head pending[BTRFS_MAX_LEVEL];
99         /* list of backref nodes with no child node */
100         struct list_head leaves;
101         /* list of blocks that have been cowed in current transaction */
102         struct list_head changed;
103         /* list of detached backref node. */
104         struct list_head detached;
105
106         u64 last_trans;
107
108         int nr_nodes;
109         int nr_edges;
110 };
111
112 /*
113  * map address of tree root to tree
114  */
115 struct mapping_node {
116         struct rb_node rb_node;
117         u64 bytenr;
118         void *data;
119 };
120
121 struct mapping_tree {
122         struct rb_root rb_root;
123         spinlock_t lock;
124 };
125
126 /*
127  * present a tree block to process
128  */
129 struct tree_block {
130         struct rb_node rb_node;
131         u64 bytenr;
132         struct btrfs_key key;
133         unsigned int level:8;
134         unsigned int key_ready:1;
135 };
136
137 #define MAX_EXTENTS 128
138
139 struct file_extent_cluster {
140         u64 start;
141         u64 end;
142         u64 boundary[MAX_EXTENTS];
143         unsigned int nr;
144 };
145
146 struct reloc_control {
147         /* block group to relocate */
148         struct btrfs_block_group_cache *block_group;
149         /* extent tree */
150         struct btrfs_root *extent_root;
151         /* inode for moving data */
152         struct inode *data_inode;
153
154         struct btrfs_block_rsv *block_rsv;
155
156         struct backref_cache backref_cache;
157
158         struct file_extent_cluster cluster;
159         /* tree blocks have been processed */
160         struct extent_io_tree processed_blocks;
161         /* map start of tree root to corresponding reloc tree */
162         struct mapping_tree reloc_root_tree;
163         /* list of reloc trees */
164         struct list_head reloc_roots;
165         /* list of subvolume trees that get relocated */
166         struct list_head dirty_subvol_roots;
167         /* size of metadata reservation for merging reloc trees */
168         u64 merging_rsv_size;
169         /* size of relocated tree nodes */
170         u64 nodes_relocated;
171         /* reserved size for block group relocation*/
172         u64 reserved_bytes;
173
174         u64 search_start;
175         u64 extents_found;
176
177         unsigned int stage:8;
178         unsigned int create_reloc_tree:1;
179         unsigned int merge_reloc_tree:1;
180         unsigned int found_file_extent:1;
181 };
182
183 /* stages of data relocation */
184 #define MOVE_DATA_EXTENTS       0
185 #define UPDATE_DATA_PTRS        1
186
187 static void remove_backref_node(struct backref_cache *cache,
188                                 struct backref_node *node);
189 static void __mark_block_processed(struct reloc_control *rc,
190                                    struct backref_node *node);
191
192 static void mapping_tree_init(struct mapping_tree *tree)
193 {
194         tree->rb_root = RB_ROOT;
195         spin_lock_init(&tree->lock);
196 }
197
198 static void backref_cache_init(struct backref_cache *cache)
199 {
200         int i;
201         cache->rb_root = RB_ROOT;
202         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
203                 INIT_LIST_HEAD(&cache->pending[i]);
204         INIT_LIST_HEAD(&cache->changed);
205         INIT_LIST_HEAD(&cache->detached);
206         INIT_LIST_HEAD(&cache->leaves);
207 }
208
209 static void backref_cache_cleanup(struct backref_cache *cache)
210 {
211         struct backref_node *node;
212         int i;
213
214         while (!list_empty(&cache->detached)) {
215                 node = list_entry(cache->detached.next,
216                                   struct backref_node, list);
217                 remove_backref_node(cache, node);
218         }
219
220         while (!list_empty(&cache->leaves)) {
221                 node = list_entry(cache->leaves.next,
222                                   struct backref_node, lower);
223                 remove_backref_node(cache, node);
224         }
225
226         cache->last_trans = 0;
227
228         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
229                 ASSERT(list_empty(&cache->pending[i]));
230         ASSERT(list_empty(&cache->changed));
231         ASSERT(list_empty(&cache->detached));
232         ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
233         ASSERT(!cache->nr_nodes);
234         ASSERT(!cache->nr_edges);
235 }
236
237 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
238 {
239         struct backref_node *node;
240
241         node = kzalloc(sizeof(*node), GFP_NOFS);
242         if (node) {
243                 INIT_LIST_HEAD(&node->list);
244                 INIT_LIST_HEAD(&node->upper);
245                 INIT_LIST_HEAD(&node->lower);
246                 RB_CLEAR_NODE(&node->rb_node);
247                 cache->nr_nodes++;
248         }
249         return node;
250 }
251
252 static void free_backref_node(struct backref_cache *cache,
253                               struct backref_node *node)
254 {
255         if (node) {
256                 cache->nr_nodes--;
257                 kfree(node);
258         }
259 }
260
261 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
262 {
263         struct backref_edge *edge;
264
265         edge = kzalloc(sizeof(*edge), GFP_NOFS);
266         if (edge)
267                 cache->nr_edges++;
268         return edge;
269 }
270
271 static void free_backref_edge(struct backref_cache *cache,
272                               struct backref_edge *edge)
273 {
274         if (edge) {
275                 cache->nr_edges--;
276                 kfree(edge);
277         }
278 }
279
280 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
281                                    struct rb_node *node)
282 {
283         struct rb_node **p = &root->rb_node;
284         struct rb_node *parent = NULL;
285         struct tree_entry *entry;
286
287         while (*p) {
288                 parent = *p;
289                 entry = rb_entry(parent, struct tree_entry, rb_node);
290
291                 if (bytenr < entry->bytenr)
292                         p = &(*p)->rb_left;
293                 else if (bytenr > entry->bytenr)
294                         p = &(*p)->rb_right;
295                 else
296                         return parent;
297         }
298
299         rb_link_node(node, parent, p);
300         rb_insert_color(node, root);
301         return NULL;
302 }
303
304 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
305 {
306         struct rb_node *n = root->rb_node;
307         struct tree_entry *entry;
308
309         while (n) {
310                 entry = rb_entry(n, struct tree_entry, rb_node);
311
312                 if (bytenr < entry->bytenr)
313                         n = n->rb_left;
314                 else if (bytenr > entry->bytenr)
315                         n = n->rb_right;
316                 else
317                         return n;
318         }
319         return NULL;
320 }
321
322 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
323 {
324
325         struct btrfs_fs_info *fs_info = NULL;
326         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
327                                               rb_node);
328         if (bnode->root)
329                 fs_info = bnode->root->fs_info;
330         btrfs_panic(fs_info, errno,
331                     "Inconsistency in backref cache found at offset %llu",
332                     bytenr);
333 }
334
335 /*
336  * walk up backref nodes until reach node presents tree root
337  */
338 static struct backref_node *walk_up_backref(struct backref_node *node,
339                                             struct backref_edge *edges[],
340                                             int *index)
341 {
342         struct backref_edge *edge;
343         int idx = *index;
344
345         while (!list_empty(&node->upper)) {
346                 edge = list_entry(node->upper.next,
347                                   struct backref_edge, list[LOWER]);
348                 edges[idx++] = edge;
349                 node = edge->node[UPPER];
350         }
351         BUG_ON(node->detached);
352         *index = idx;
353         return node;
354 }
355
356 /*
357  * walk down backref nodes to find start of next reference path
358  */
359 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
360                                               int *index)
361 {
362         struct backref_edge *edge;
363         struct backref_node *lower;
364         int idx = *index;
365
366         while (idx > 0) {
367                 edge = edges[idx - 1];
368                 lower = edge->node[LOWER];
369                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
370                         idx--;
371                         continue;
372                 }
373                 edge = list_entry(edge->list[LOWER].next,
374                                   struct backref_edge, list[LOWER]);
375                 edges[idx - 1] = edge;
376                 *index = idx;
377                 return edge->node[UPPER];
378         }
379         *index = 0;
380         return NULL;
381 }
382
383 static void unlock_node_buffer(struct backref_node *node)
384 {
385         if (node->locked) {
386                 btrfs_tree_unlock(node->eb);
387                 node->locked = 0;
388         }
389 }
390
391 static void drop_node_buffer(struct backref_node *node)
392 {
393         if (node->eb) {
394                 unlock_node_buffer(node);
395                 free_extent_buffer(node->eb);
396                 node->eb = NULL;
397         }
398 }
399
400 static void drop_backref_node(struct backref_cache *tree,
401                               struct backref_node *node)
402 {
403         BUG_ON(!list_empty(&node->upper));
404
405         drop_node_buffer(node);
406         list_del(&node->list);
407         list_del(&node->lower);
408         if (!RB_EMPTY_NODE(&node->rb_node))
409                 rb_erase(&node->rb_node, &tree->rb_root);
410         free_backref_node(tree, node);
411 }
412
413 /*
414  * remove a backref node from the backref cache
415  */
416 static void remove_backref_node(struct backref_cache *cache,
417                                 struct backref_node *node)
418 {
419         struct backref_node *upper;
420         struct backref_edge *edge;
421
422         if (!node)
423                 return;
424
425         BUG_ON(!node->lowest && !node->detached);
426         while (!list_empty(&node->upper)) {
427                 edge = list_entry(node->upper.next, struct backref_edge,
428                                   list[LOWER]);
429                 upper = edge->node[UPPER];
430                 list_del(&edge->list[LOWER]);
431                 list_del(&edge->list[UPPER]);
432                 free_backref_edge(cache, edge);
433
434                 if (RB_EMPTY_NODE(&upper->rb_node)) {
435                         BUG_ON(!list_empty(&node->upper));
436                         drop_backref_node(cache, node);
437                         node = upper;
438                         node->lowest = 1;
439                         continue;
440                 }
441                 /*
442                  * add the node to leaf node list if no other
443                  * child block cached.
444                  */
445                 if (list_empty(&upper->lower)) {
446                         list_add_tail(&upper->lower, &cache->leaves);
447                         upper->lowest = 1;
448                 }
449         }
450
451         drop_backref_node(cache, node);
452 }
453
454 static void update_backref_node(struct backref_cache *cache,
455                                 struct backref_node *node, u64 bytenr)
456 {
457         struct rb_node *rb_node;
458         rb_erase(&node->rb_node, &cache->rb_root);
459         node->bytenr = bytenr;
460         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
461         if (rb_node)
462                 backref_tree_panic(rb_node, -EEXIST, bytenr);
463 }
464
465 /*
466  * update backref cache after a transaction commit
467  */
468 static int update_backref_cache(struct btrfs_trans_handle *trans,
469                                 struct backref_cache *cache)
470 {
471         struct backref_node *node;
472         int level = 0;
473
474         if (cache->last_trans == 0) {
475                 cache->last_trans = trans->transid;
476                 return 0;
477         }
478
479         if (cache->last_trans == trans->transid)
480                 return 0;
481
482         /*
483          * detached nodes are used to avoid unnecessary backref
484          * lookup. transaction commit changes the extent tree.
485          * so the detached nodes are no longer useful.
486          */
487         while (!list_empty(&cache->detached)) {
488                 node = list_entry(cache->detached.next,
489                                   struct backref_node, list);
490                 remove_backref_node(cache, node);
491         }
492
493         while (!list_empty(&cache->changed)) {
494                 node = list_entry(cache->changed.next,
495                                   struct backref_node, list);
496                 list_del_init(&node->list);
497                 BUG_ON(node->pending);
498                 update_backref_node(cache, node, node->new_bytenr);
499         }
500
501         /*
502          * some nodes can be left in the pending list if there were
503          * errors during processing the pending nodes.
504          */
505         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
506                 list_for_each_entry(node, &cache->pending[level], list) {
507                         BUG_ON(!node->pending);
508                         if (node->bytenr == node->new_bytenr)
509                                 continue;
510                         update_backref_node(cache, node, node->new_bytenr);
511                 }
512         }
513
514         cache->last_trans = 0;
515         return 1;
516 }
517
518
519 static int should_ignore_root(struct btrfs_root *root)
520 {
521         struct btrfs_root *reloc_root;
522
523         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
524                 return 0;
525
526         reloc_root = root->reloc_root;
527         if (!reloc_root)
528                 return 0;
529
530         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
531             root->fs_info->running_transaction->transid - 1)
532                 return 0;
533         /*
534          * if there is reloc tree and it was created in previous
535          * transaction backref lookup can find the reloc tree,
536          * so backref node for the fs tree root is useless for
537          * relocation.
538          */
539         return 1;
540 }
541 /*
542  * find reloc tree by address of tree root
543  */
544 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
545                                           u64 bytenr)
546 {
547         struct rb_node *rb_node;
548         struct mapping_node *node;
549         struct btrfs_root *root = NULL;
550
551         spin_lock(&rc->reloc_root_tree.lock);
552         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
553         if (rb_node) {
554                 node = rb_entry(rb_node, struct mapping_node, rb_node);
555                 root = (struct btrfs_root *)node->data;
556         }
557         spin_unlock(&rc->reloc_root_tree.lock);
558         return root;
559 }
560
561 static int is_cowonly_root(u64 root_objectid)
562 {
563         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
564             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
565             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
566             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
567             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
568             root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
569             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
570             root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
571             root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
572                 return 1;
573         return 0;
574 }
575
576 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
577                                         u64 root_objectid)
578 {
579         struct btrfs_key key;
580
581         key.objectid = root_objectid;
582         key.type = BTRFS_ROOT_ITEM_KEY;
583         if (is_cowonly_root(root_objectid))
584                 key.offset = 0;
585         else
586                 key.offset = (u64)-1;
587
588         return btrfs_get_fs_root(fs_info, &key, false);
589 }
590
591 static noinline_for_stack
592 int find_inline_backref(struct extent_buffer *leaf, int slot,
593                         unsigned long *ptr, unsigned long *end)
594 {
595         struct btrfs_key key;
596         struct btrfs_extent_item *ei;
597         struct btrfs_tree_block_info *bi;
598         u32 item_size;
599
600         btrfs_item_key_to_cpu(leaf, &key, slot);
601
602         item_size = btrfs_item_size_nr(leaf, slot);
603         if (item_size < sizeof(*ei)) {
604                 btrfs_print_v0_err(leaf->fs_info);
605                 btrfs_handle_fs_error(leaf->fs_info, -EINVAL, NULL);
606                 return 1;
607         }
608         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
609         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
610                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
611
612         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
613             item_size <= sizeof(*ei) + sizeof(*bi)) {
614                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
615                 return 1;
616         }
617         if (key.type == BTRFS_METADATA_ITEM_KEY &&
618             item_size <= sizeof(*ei)) {
619                 WARN_ON(item_size < sizeof(*ei));
620                 return 1;
621         }
622
623         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
624                 bi = (struct btrfs_tree_block_info *)(ei + 1);
625                 *ptr = (unsigned long)(bi + 1);
626         } else {
627                 *ptr = (unsigned long)(ei + 1);
628         }
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 reference the block, and then check
640  * backrefs 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; /* For searching extent root */
654         struct btrfs_path *path2; /* For searching parent of TREE_BLOCK_REF */
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); /* Pending edge list, upper node needs to be checked */
668         LIST_HEAD(useless);
669         int cowonly;
670         int ret;
671         int err = 0;
672         bool need_check = true;
673
674         path1 = btrfs_alloc_path();
675         path2 = btrfs_alloc_path();
676         if (!path1 || !path2) {
677                 err = -ENOMEM;
678                 goto out;
679         }
680         path1->reada = READA_FORWARD;
681         path2->reada = READA_FORWARD;
682
683         node = alloc_backref_node(cache);
684         if (!node) {
685                 err = -ENOMEM;
686                 goto out;
687         }
688
689         node->bytenr = bytenr;
690         node->level = level;
691         node->lowest = 1;
692         cur = node;
693 again:
694         end = 0;
695         ptr = 0;
696         key.objectid = cur->bytenr;
697         key.type = BTRFS_METADATA_ITEM_KEY;
698         key.offset = (u64)-1;
699
700         path1->search_commit_root = 1;
701         path1->skip_locking = 1;
702         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
703                                 0, 0);
704         if (ret < 0) {
705                 err = ret;
706                 goto out;
707         }
708         ASSERT(ret);
709         ASSERT(path1->slots[0]);
710
711         path1->slots[0]--;
712
713         WARN_ON(cur->checked);
714         if (!list_empty(&cur->upper)) {
715                 /*
716                  * the backref was added previously when processing
717                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
718                  */
719                 ASSERT(list_is_singular(&cur->upper));
720                 edge = list_entry(cur->upper.next, struct backref_edge,
721                                   list[LOWER]);
722                 ASSERT(list_empty(&edge->list[UPPER]));
723                 exist = edge->node[UPPER];
724                 /*
725                  * add the upper level block to pending list if we need
726                  * check its backrefs
727                  */
728                 if (!exist->checked)
729                         list_add_tail(&edge->list[UPPER], &list);
730         } else {
731                 exist = NULL;
732         }
733
734         while (1) {
735                 cond_resched();
736                 eb = path1->nodes[0];
737
738                 if (ptr >= end) {
739                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
740                                 ret = btrfs_next_leaf(rc->extent_root, path1);
741                                 if (ret < 0) {
742                                         err = ret;
743                                         goto out;
744                                 }
745                                 if (ret > 0)
746                                         break;
747                                 eb = path1->nodes[0];
748                         }
749
750                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
751                         if (key.objectid != cur->bytenr) {
752                                 WARN_ON(exist);
753                                 break;
754                         }
755
756                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
757                             key.type == BTRFS_METADATA_ITEM_KEY) {
758                                 ret = find_inline_backref(eb, path1->slots[0],
759                                                           &ptr, &end);
760                                 if (ret)
761                                         goto next;
762                         }
763                 }
764
765                 if (ptr < end) {
766                         /* update key for inline back ref */
767                         struct btrfs_extent_inline_ref *iref;
768                         int type;
769                         iref = (struct btrfs_extent_inline_ref *)ptr;
770                         type = btrfs_get_extent_inline_ref_type(eb, iref,
771                                                         BTRFS_REF_TYPE_BLOCK);
772                         if (type == BTRFS_REF_TYPE_INVALID) {
773                                 err = -EUCLEAN;
774                                 goto out;
775                         }
776                         key.type = type;
777                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
778
779                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
780                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
781                 }
782
783                 /*
784                  * Parent node found and matches current inline ref, no need to
785                  * rebuild this node for this inline ref.
786                  */
787                 if (exist &&
788                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
789                       exist->owner == key.offset) ||
790                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
791                       exist->bytenr == key.offset))) {
792                         exist = NULL;
793                         goto next;
794                 }
795
796                 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */
797                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
798                         if (key.objectid == key.offset) {
799                                 /*
800                                  * Only root blocks of reloc trees use backref
801                                  * pointing to itself.
802                                  */
803                                 root = find_reloc_root(rc, cur->bytenr);
804                                 ASSERT(root);
805                                 cur->root = root;
806                                 break;
807                         }
808
809                         edge = alloc_backref_edge(cache);
810                         if (!edge) {
811                                 err = -ENOMEM;
812                                 goto out;
813                         }
814                         rb_node = tree_search(&cache->rb_root, key.offset);
815                         if (!rb_node) {
816                                 upper = alloc_backref_node(cache);
817                                 if (!upper) {
818                                         free_backref_edge(cache, edge);
819                                         err = -ENOMEM;
820                                         goto out;
821                                 }
822                                 upper->bytenr = key.offset;
823                                 upper->level = cur->level + 1;
824                                 /*
825                                  *  backrefs for the upper level block isn't
826                                  *  cached, add the block to pending list
827                                  */
828                                 list_add_tail(&edge->list[UPPER], &list);
829                         } else {
830                                 upper = rb_entry(rb_node, struct backref_node,
831                                                  rb_node);
832                                 ASSERT(upper->checked);
833                                 INIT_LIST_HEAD(&edge->list[UPPER]);
834                         }
835                         list_add_tail(&edge->list[LOWER], &cur->upper);
836                         edge->node[LOWER] = cur;
837                         edge->node[UPPER] = upper;
838
839                         goto next;
840                 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
841                         err = -EINVAL;
842                         btrfs_print_v0_err(rc->extent_root->fs_info);
843                         btrfs_handle_fs_error(rc->extent_root->fs_info, err,
844                                               NULL);
845                         goto out;
846                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
847                         goto next;
848                 }
849
850                 /*
851                  * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset
852                  * means the root objectid. We need to search the tree to get
853                  * its parent bytenr.
854                  */
855                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
856                 if (IS_ERR(root)) {
857                         err = PTR_ERR(root);
858                         goto out;
859                 }
860
861                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
862                         cur->cowonly = 1;
863
864                 if (btrfs_root_level(&root->root_item) == cur->level) {
865                         /* tree root */
866                         ASSERT(btrfs_root_bytenr(&root->root_item) ==
867                                cur->bytenr);
868                         if (should_ignore_root(root))
869                                 list_add(&cur->list, &useless);
870                         else
871                                 cur->root = root;
872                         break;
873                 }
874
875                 level = cur->level + 1;
876
877                 /* Search the tree to find parent blocks referring the block. */
878                 path2->search_commit_root = 1;
879                 path2->skip_locking = 1;
880                 path2->lowest_level = level;
881                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
882                 path2->lowest_level = 0;
883                 if (ret < 0) {
884                         err = ret;
885                         goto out;
886                 }
887                 if (ret > 0 && path2->slots[level] > 0)
888                         path2->slots[level]--;
889
890                 eb = path2->nodes[level];
891                 if (btrfs_node_blockptr(eb, path2->slots[level]) !=
892                     cur->bytenr) {
893                         btrfs_err(root->fs_info,
894         "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
895                                   cur->bytenr, level - 1,
896                                   root->root_key.objectid,
897                                   node_key->objectid, node_key->type,
898                                   node_key->offset);
899                         err = -ENOENT;
900                         goto out;
901                 }
902                 lower = cur;
903                 need_check = true;
904
905                 /* Add all nodes and edges in the path */
906                 for (; level < BTRFS_MAX_LEVEL; level++) {
907                         if (!path2->nodes[level]) {
908                                 ASSERT(btrfs_root_bytenr(&root->root_item) ==
909                                        lower->bytenr);
910                                 if (should_ignore_root(root))
911                                         list_add(&lower->list, &useless);
912                                 else
913                                         lower->root = root;
914                                 break;
915                         }
916
917                         edge = alloc_backref_edge(cache);
918                         if (!edge) {
919                                 err = -ENOMEM;
920                                 goto out;
921                         }
922
923                         eb = path2->nodes[level];
924                         rb_node = tree_search(&cache->rb_root, eb->start);
925                         if (!rb_node) {
926                                 upper = alloc_backref_node(cache);
927                                 if (!upper) {
928                                         free_backref_edge(cache, edge);
929                                         err = -ENOMEM;
930                                         goto out;
931                                 }
932                                 upper->bytenr = eb->start;
933                                 upper->owner = btrfs_header_owner(eb);
934                                 upper->level = lower->level + 1;
935                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
936                                               &root->state))
937                                         upper->cowonly = 1;
938
939                                 /*
940                                  * if we know the block isn't shared
941                                  * we can void checking its backrefs.
942                                  */
943                                 if (btrfs_block_can_be_shared(root, eb))
944                                         upper->checked = 0;
945                                 else
946                                         upper->checked = 1;
947
948                                 /*
949                                  * add the block to pending list if we
950                                  * need check its backrefs, we only do this once
951                                  * while walking up a tree as we will catch
952                                  * anything else later on.
953                                  */
954                                 if (!upper->checked && need_check) {
955                                         need_check = false;
956                                         list_add_tail(&edge->list[UPPER],
957                                                       &list);
958                                 } else {
959                                         if (upper->checked)
960                                                 need_check = true;
961                                         INIT_LIST_HEAD(&edge->list[UPPER]);
962                                 }
963                         } else {
964                                 upper = rb_entry(rb_node, struct backref_node,
965                                                  rb_node);
966                                 ASSERT(upper->checked);
967                                 INIT_LIST_HEAD(&edge->list[UPPER]);
968                                 if (!upper->owner)
969                                         upper->owner = btrfs_header_owner(eb);
970                         }
971                         list_add_tail(&edge->list[LOWER], &lower->upper);
972                         edge->node[LOWER] = lower;
973                         edge->node[UPPER] = upper;
974
975                         if (rb_node)
976                                 break;
977                         lower = upper;
978                         upper = NULL;
979                 }
980                 btrfs_release_path(path2);
981 next:
982                 if (ptr < end) {
983                         ptr += btrfs_extent_inline_ref_size(key.type);
984                         if (ptr >= end) {
985                                 WARN_ON(ptr > end);
986                                 ptr = 0;
987                                 end = 0;
988                         }
989                 }
990                 if (ptr >= end)
991                         path1->slots[0]++;
992         }
993         btrfs_release_path(path1);
994
995         cur->checked = 1;
996         WARN_ON(exist);
997
998         /* the pending list isn't empty, take the first block to process */
999         if (!list_empty(&list)) {
1000                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1001                 list_del_init(&edge->list[UPPER]);
1002                 cur = edge->node[UPPER];
1003                 goto again;
1004         }
1005
1006         /*
1007          * everything goes well, connect backref nodes and insert backref nodes
1008          * into the cache.
1009          */
1010         ASSERT(node->checked);
1011         cowonly = node->cowonly;
1012         if (!cowonly) {
1013                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1014                                       &node->rb_node);
1015                 if (rb_node)
1016                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1017                 list_add_tail(&node->lower, &cache->leaves);
1018         }
1019
1020         list_for_each_entry(edge, &node->upper, list[LOWER])
1021                 list_add_tail(&edge->list[UPPER], &list);
1022
1023         while (!list_empty(&list)) {
1024                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1025                 list_del_init(&edge->list[UPPER]);
1026                 upper = edge->node[UPPER];
1027                 if (upper->detached) {
1028                         list_del(&edge->list[LOWER]);
1029                         lower = edge->node[LOWER];
1030                         free_backref_edge(cache, edge);
1031                         if (list_empty(&lower->upper))
1032                                 list_add(&lower->list, &useless);
1033                         continue;
1034                 }
1035
1036                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1037                         if (upper->lowest) {
1038                                 list_del_init(&upper->lower);
1039                                 upper->lowest = 0;
1040                         }
1041
1042                         list_add_tail(&edge->list[UPPER], &upper->lower);
1043                         continue;
1044                 }
1045
1046                 if (!upper->checked) {
1047                         /*
1048                          * Still want to blow up for developers since this is a
1049                          * logic bug.
1050                          */
1051                         ASSERT(0);
1052                         err = -EINVAL;
1053                         goto out;
1054                 }
1055                 if (cowonly != upper->cowonly) {
1056                         ASSERT(0);
1057                         err = -EINVAL;
1058                         goto out;
1059                 }
1060
1061                 if (!cowonly) {
1062                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1063                                               &upper->rb_node);
1064                         if (rb_node)
1065                                 backref_tree_panic(rb_node, -EEXIST,
1066                                                    upper->bytenr);
1067                 }
1068
1069                 list_add_tail(&edge->list[UPPER], &upper->lower);
1070
1071                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1072                         list_add_tail(&edge->list[UPPER], &list);
1073         }
1074         /*
1075          * process useless backref nodes. backref nodes for tree leaves
1076          * are deleted from the cache. backref nodes for upper level
1077          * tree blocks are left in the cache to avoid unnecessary backref
1078          * lookup.
1079          */
1080         while (!list_empty(&useless)) {
1081                 upper = list_entry(useless.next, struct backref_node, list);
1082                 list_del_init(&upper->list);
1083                 ASSERT(list_empty(&upper->upper));
1084                 if (upper == node)
1085                         node = NULL;
1086                 if (upper->lowest) {
1087                         list_del_init(&upper->lower);
1088                         upper->lowest = 0;
1089                 }
1090                 while (!list_empty(&upper->lower)) {
1091                         edge = list_entry(upper->lower.next,
1092                                           struct backref_edge, list[UPPER]);
1093                         list_del(&edge->list[UPPER]);
1094                         list_del(&edge->list[LOWER]);
1095                         lower = edge->node[LOWER];
1096                         free_backref_edge(cache, edge);
1097
1098                         if (list_empty(&lower->upper))
1099                                 list_add(&lower->list, &useless);
1100                 }
1101                 __mark_block_processed(rc, upper);
1102                 if (upper->level > 0) {
1103                         list_add(&upper->list, &cache->detached);
1104                         upper->detached = 1;
1105                 } else {
1106                         rb_erase(&upper->rb_node, &cache->rb_root);
1107                         free_backref_node(cache, upper);
1108                 }
1109         }
1110 out:
1111         btrfs_free_path(path1);
1112         btrfs_free_path(path2);
1113         if (err) {
1114                 while (!list_empty(&useless)) {
1115                         lower = list_entry(useless.next,
1116                                            struct backref_node, list);
1117                         list_del_init(&lower->list);
1118                 }
1119                 while (!list_empty(&list)) {
1120                         edge = list_first_entry(&list, struct backref_edge,
1121                                                 list[UPPER]);
1122                         list_del(&edge->list[UPPER]);
1123                         list_del(&edge->list[LOWER]);
1124                         lower = edge->node[LOWER];
1125                         upper = edge->node[UPPER];
1126                         free_backref_edge(cache, edge);
1127
1128                         /*
1129                          * Lower is no longer linked to any upper backref nodes
1130                          * and isn't in the cache, we can free it ourselves.
1131                          */
1132                         if (list_empty(&lower->upper) &&
1133                             RB_EMPTY_NODE(&lower->rb_node))
1134                                 list_add(&lower->list, &useless);
1135
1136                         if (!RB_EMPTY_NODE(&upper->rb_node))
1137                                 continue;
1138
1139                         /* Add this guy's upper edges to the list to process */
1140                         list_for_each_entry(edge, &upper->upper, list[LOWER])
1141                                 list_add_tail(&edge->list[UPPER], &list);
1142                         if (list_empty(&upper->upper))
1143                                 list_add(&upper->list, &useless);
1144                 }
1145
1146                 while (!list_empty(&useless)) {
1147                         lower = list_entry(useless.next,
1148                                            struct backref_node, list);
1149                         list_del_init(&lower->list);
1150                         if (lower == node)
1151                                 node = NULL;
1152                         free_backref_node(cache, lower);
1153                 }
1154
1155                 free_backref_node(cache, node);
1156                 return ERR_PTR(err);
1157         }
1158         ASSERT(!node || !node->detached);
1159         return node;
1160 }
1161
1162 /*
1163  * helper to add backref node for the newly created snapshot.
1164  * the backref node is created by cloning backref node that
1165  * corresponds to root of source tree
1166  */
1167 static int clone_backref_node(struct btrfs_trans_handle *trans,
1168                               struct reloc_control *rc,
1169                               struct btrfs_root *src,
1170                               struct btrfs_root *dest)
1171 {
1172         struct btrfs_root *reloc_root = src->reloc_root;
1173         struct backref_cache *cache = &rc->backref_cache;
1174         struct backref_node *node = NULL;
1175         struct backref_node *new_node;
1176         struct backref_edge *edge;
1177         struct backref_edge *new_edge;
1178         struct rb_node *rb_node;
1179
1180         if (cache->last_trans > 0)
1181                 update_backref_cache(trans, cache);
1182
1183         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1184         if (rb_node) {
1185                 node = rb_entry(rb_node, struct backref_node, rb_node);
1186                 if (node->detached)
1187                         node = NULL;
1188                 else
1189                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1190         }
1191
1192         if (!node) {
1193                 rb_node = tree_search(&cache->rb_root,
1194                                       reloc_root->commit_root->start);
1195                 if (rb_node) {
1196                         node = rb_entry(rb_node, struct backref_node,
1197                                         rb_node);
1198                         BUG_ON(node->detached);
1199                 }
1200         }
1201
1202         if (!node)
1203                 return 0;
1204
1205         new_node = alloc_backref_node(cache);
1206         if (!new_node)
1207                 return -ENOMEM;
1208
1209         new_node->bytenr = dest->node->start;
1210         new_node->level = node->level;
1211         new_node->lowest = node->lowest;
1212         new_node->checked = 1;
1213         new_node->root = dest;
1214
1215         if (!node->lowest) {
1216                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1217                         new_edge = alloc_backref_edge(cache);
1218                         if (!new_edge)
1219                                 goto fail;
1220
1221                         new_edge->node[UPPER] = new_node;
1222                         new_edge->node[LOWER] = edge->node[LOWER];
1223                         list_add_tail(&new_edge->list[UPPER],
1224                                       &new_node->lower);
1225                 }
1226         } else {
1227                 list_add_tail(&new_node->lower, &cache->leaves);
1228         }
1229
1230         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1231                               &new_node->rb_node);
1232         if (rb_node)
1233                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1234
1235         if (!new_node->lowest) {
1236                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1237                         list_add_tail(&new_edge->list[LOWER],
1238                                       &new_edge->node[LOWER]->upper);
1239                 }
1240         }
1241         return 0;
1242 fail:
1243         while (!list_empty(&new_node->lower)) {
1244                 new_edge = list_entry(new_node->lower.next,
1245                                       struct backref_edge, list[UPPER]);
1246                 list_del(&new_edge->list[UPPER]);
1247                 free_backref_edge(cache, new_edge);
1248         }
1249         free_backref_node(cache, new_node);
1250         return -ENOMEM;
1251 }
1252
1253 /*
1254  * helper to add 'address of tree root -> reloc tree' mapping
1255  */
1256 static int __must_check __add_reloc_root(struct btrfs_root *root)
1257 {
1258         struct btrfs_fs_info *fs_info = root->fs_info;
1259         struct rb_node *rb_node;
1260         struct mapping_node *node;
1261         struct reloc_control *rc = fs_info->reloc_ctl;
1262
1263         node = kmalloc(sizeof(*node), GFP_NOFS);
1264         if (!node)
1265                 return -ENOMEM;
1266
1267         node->bytenr = root->node->start;
1268         node->data = root;
1269
1270         spin_lock(&rc->reloc_root_tree.lock);
1271         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1272                               node->bytenr, &node->rb_node);
1273         spin_unlock(&rc->reloc_root_tree.lock);
1274         if (rb_node) {
1275                 btrfs_panic(fs_info, -EEXIST,
1276                             "Duplicate root found for start=%llu while inserting into relocation tree",
1277                             node->bytenr);
1278         }
1279
1280         list_add_tail(&root->root_list, &rc->reloc_roots);
1281         return 0;
1282 }
1283
1284 /*
1285  * helper to delete the 'address of tree root -> reloc tree'
1286  * mapping
1287  */
1288 static void __del_reloc_root(struct btrfs_root *root)
1289 {
1290         struct btrfs_fs_info *fs_info = root->fs_info;
1291         struct rb_node *rb_node;
1292         struct mapping_node *node = NULL;
1293         struct reloc_control *rc = fs_info->reloc_ctl;
1294
1295         if (rc && root->node) {
1296                 spin_lock(&rc->reloc_root_tree.lock);
1297                 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1298                                       root->node->start);
1299                 if (rb_node) {
1300                         node = rb_entry(rb_node, struct mapping_node, rb_node);
1301                         rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1302                 }
1303                 spin_unlock(&rc->reloc_root_tree.lock);
1304                 if (!node)
1305                         return;
1306                 BUG_ON((struct btrfs_root *)node->data != root);
1307         }
1308
1309         spin_lock(&fs_info->trans_lock);
1310         list_del_init(&root->root_list);
1311         spin_unlock(&fs_info->trans_lock);
1312         kfree(node);
1313 }
1314
1315 /*
1316  * helper to update the 'address of tree root -> reloc tree'
1317  * mapping
1318  */
1319 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1320 {
1321         struct btrfs_fs_info *fs_info = root->fs_info;
1322         struct rb_node *rb_node;
1323         struct mapping_node *node = NULL;
1324         struct reloc_control *rc = fs_info->reloc_ctl;
1325
1326         spin_lock(&rc->reloc_root_tree.lock);
1327         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1328                               root->node->start);
1329         if (rb_node) {
1330                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1331                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1332         }
1333         spin_unlock(&rc->reloc_root_tree.lock);
1334
1335         if (!node)
1336                 return 0;
1337         BUG_ON((struct btrfs_root *)node->data != root);
1338
1339         spin_lock(&rc->reloc_root_tree.lock);
1340         node->bytenr = new_bytenr;
1341         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1342                               node->bytenr, &node->rb_node);
1343         spin_unlock(&rc->reloc_root_tree.lock);
1344         if (rb_node)
1345                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1346         return 0;
1347 }
1348
1349 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1350                                         struct btrfs_root *root, u64 objectid)
1351 {
1352         struct btrfs_fs_info *fs_info = root->fs_info;
1353         struct btrfs_root *reloc_root;
1354         struct extent_buffer *eb;
1355         struct btrfs_root_item *root_item;
1356         struct btrfs_key root_key;
1357         int ret;
1358
1359         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1360         BUG_ON(!root_item);
1361
1362         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1363         root_key.type = BTRFS_ROOT_ITEM_KEY;
1364         root_key.offset = objectid;
1365
1366         if (root->root_key.objectid == objectid) {
1367                 u64 commit_root_gen;
1368
1369                 /* called by btrfs_init_reloc_root */
1370                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1371                                       BTRFS_TREE_RELOC_OBJECTID);
1372                 BUG_ON(ret);
1373                 /*
1374                  * Set the last_snapshot field to the generation of the commit
1375                  * root - like this ctree.c:btrfs_block_can_be_shared() behaves
1376                  * correctly (returns true) when the relocation root is created
1377                  * either inside the critical section of a transaction commit
1378                  * (through transaction.c:qgroup_account_snapshot()) and when
1379                  * it's created before the transaction commit is started.
1380                  */
1381                 commit_root_gen = btrfs_header_generation(root->commit_root);
1382                 btrfs_set_root_last_snapshot(&root->root_item, commit_root_gen);
1383         } else {
1384                 /*
1385                  * called by btrfs_reloc_post_snapshot_hook.
1386                  * the source tree is a reloc tree, all tree blocks
1387                  * modified after it was created have RELOC flag
1388                  * set in their headers. so it's OK to not update
1389                  * the 'last_snapshot'.
1390                  */
1391                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1392                                       BTRFS_TREE_RELOC_OBJECTID);
1393                 BUG_ON(ret);
1394         }
1395
1396         memcpy(root_item, &root->root_item, sizeof(*root_item));
1397         btrfs_set_root_bytenr(root_item, eb->start);
1398         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1399         btrfs_set_root_generation(root_item, trans->transid);
1400
1401         if (root->root_key.objectid == objectid) {
1402                 btrfs_set_root_refs(root_item, 0);
1403                 memset(&root_item->drop_progress, 0,
1404                        sizeof(struct btrfs_disk_key));
1405                 root_item->drop_level = 0;
1406         }
1407
1408         btrfs_tree_unlock(eb);
1409         free_extent_buffer(eb);
1410
1411         ret = btrfs_insert_root(trans, fs_info->tree_root,
1412                                 &root_key, root_item);
1413         BUG_ON(ret);
1414         kfree(root_item);
1415
1416         reloc_root = btrfs_read_fs_root(fs_info->tree_root, &root_key);
1417         BUG_ON(IS_ERR(reloc_root));
1418         reloc_root->last_trans = trans->transid;
1419         return reloc_root;
1420 }
1421
1422 /*
1423  * create reloc tree for a given fs tree. reloc tree is just a
1424  * snapshot of the fs tree with special root objectid.
1425  */
1426 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1427                           struct btrfs_root *root)
1428 {
1429         struct btrfs_fs_info *fs_info = root->fs_info;
1430         struct btrfs_root *reloc_root;
1431         struct reloc_control *rc = fs_info->reloc_ctl;
1432         struct btrfs_block_rsv *rsv;
1433         int clear_rsv = 0;
1434         int ret;
1435
1436         if (root->reloc_root) {
1437                 reloc_root = root->reloc_root;
1438                 reloc_root->last_trans = trans->transid;
1439                 return 0;
1440         }
1441
1442         if (!rc || !rc->create_reloc_tree ||
1443             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1444                 return 0;
1445
1446         if (!trans->reloc_reserved) {
1447                 rsv = trans->block_rsv;
1448                 trans->block_rsv = rc->block_rsv;
1449                 clear_rsv = 1;
1450         }
1451         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1452         if (clear_rsv)
1453                 trans->block_rsv = rsv;
1454
1455         ret = __add_reloc_root(reloc_root);
1456         BUG_ON(ret < 0);
1457         root->reloc_root = reloc_root;
1458         return 0;
1459 }
1460
1461 /*
1462  * update root item of reloc tree
1463  */
1464 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1465                             struct btrfs_root *root)
1466 {
1467         struct btrfs_fs_info *fs_info = root->fs_info;
1468         struct btrfs_root *reloc_root;
1469         struct btrfs_root_item *root_item;
1470         int ret;
1471
1472         if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state) ||
1473             !root->reloc_root)
1474                 goto out;
1475
1476         reloc_root = root->reloc_root;
1477         root_item = &reloc_root->root_item;
1478
1479         /* root->reloc_root will stay until current relocation finished */
1480         if (fs_info->reloc_ctl->merge_reloc_tree &&
1481             btrfs_root_refs(root_item) == 0) {
1482                 set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
1483                 __del_reloc_root(reloc_root);
1484         }
1485
1486         if (reloc_root->commit_root != reloc_root->node) {
1487                 btrfs_set_root_node(root_item, reloc_root->node);
1488                 free_extent_buffer(reloc_root->commit_root);
1489                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1490         }
1491
1492         ret = btrfs_update_root(trans, fs_info->tree_root,
1493                                 &reloc_root->root_key, root_item);
1494         BUG_ON(ret);
1495
1496 out:
1497         return 0;
1498 }
1499
1500 /*
1501  * helper to find first cached inode with inode number >= objectid
1502  * in a subvolume
1503  */
1504 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1505 {
1506         struct rb_node *node;
1507         struct rb_node *prev;
1508         struct btrfs_inode *entry;
1509         struct inode *inode;
1510
1511         spin_lock(&root->inode_lock);
1512 again:
1513         node = root->inode_tree.rb_node;
1514         prev = NULL;
1515         while (node) {
1516                 prev = node;
1517                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1518
1519                 if (objectid < btrfs_ino(entry))
1520                         node = node->rb_left;
1521                 else if (objectid > btrfs_ino(entry))
1522                         node = node->rb_right;
1523                 else
1524                         break;
1525         }
1526         if (!node) {
1527                 while (prev) {
1528                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1529                         if (objectid <= btrfs_ino(entry)) {
1530                                 node = prev;
1531                                 break;
1532                         }
1533                         prev = rb_next(prev);
1534                 }
1535         }
1536         while (node) {
1537                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1538                 inode = igrab(&entry->vfs_inode);
1539                 if (inode) {
1540                         spin_unlock(&root->inode_lock);
1541                         return inode;
1542                 }
1543
1544                 objectid = btrfs_ino(entry) + 1;
1545                 if (cond_resched_lock(&root->inode_lock))
1546                         goto again;
1547
1548                 node = rb_next(node);
1549         }
1550         spin_unlock(&root->inode_lock);
1551         return NULL;
1552 }
1553
1554 static int in_block_group(u64 bytenr,
1555                           struct btrfs_block_group_cache *block_group)
1556 {
1557         if (bytenr >= block_group->key.objectid &&
1558             bytenr < block_group->key.objectid + block_group->key.offset)
1559                 return 1;
1560         return 0;
1561 }
1562
1563 /*
1564  * get new location of data
1565  */
1566 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1567                             u64 bytenr, u64 num_bytes)
1568 {
1569         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1570         struct btrfs_path *path;
1571         struct btrfs_file_extent_item *fi;
1572         struct extent_buffer *leaf;
1573         int ret;
1574
1575         path = btrfs_alloc_path();
1576         if (!path)
1577                 return -ENOMEM;
1578
1579         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1580         ret = btrfs_lookup_file_extent(NULL, root, path,
1581                         btrfs_ino(BTRFS_I(reloc_inode)), bytenr, 0);
1582         if (ret < 0)
1583                 goto out;
1584         if (ret > 0) {
1585                 ret = -ENOENT;
1586                 goto out;
1587         }
1588
1589         leaf = path->nodes[0];
1590         fi = btrfs_item_ptr(leaf, path->slots[0],
1591                             struct btrfs_file_extent_item);
1592
1593         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1594                btrfs_file_extent_compression(leaf, fi) ||
1595                btrfs_file_extent_encryption(leaf, fi) ||
1596                btrfs_file_extent_other_encoding(leaf, fi));
1597
1598         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1599                 ret = -EINVAL;
1600                 goto out;
1601         }
1602
1603         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1604         ret = 0;
1605 out:
1606         btrfs_free_path(path);
1607         return ret;
1608 }
1609
1610 /*
1611  * update file extent items in the tree leaf to point to
1612  * the new locations.
1613  */
1614 static noinline_for_stack
1615 int replace_file_extents(struct btrfs_trans_handle *trans,
1616                          struct reloc_control *rc,
1617                          struct btrfs_root *root,
1618                          struct extent_buffer *leaf)
1619 {
1620         struct btrfs_fs_info *fs_info = root->fs_info;
1621         struct btrfs_key key;
1622         struct btrfs_file_extent_item *fi;
1623         struct inode *inode = NULL;
1624         u64 parent;
1625         u64 bytenr;
1626         u64 new_bytenr = 0;
1627         u64 num_bytes;
1628         u64 end;
1629         u32 nritems;
1630         u32 i;
1631         int ret = 0;
1632         int first = 1;
1633         int dirty = 0;
1634
1635         if (rc->stage != UPDATE_DATA_PTRS)
1636                 return 0;
1637
1638         /* reloc trees always use full backref */
1639         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1640                 parent = leaf->start;
1641         else
1642                 parent = 0;
1643
1644         nritems = btrfs_header_nritems(leaf);
1645         for (i = 0; i < nritems; i++) {
1646                 cond_resched();
1647                 btrfs_item_key_to_cpu(leaf, &key, i);
1648                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1649                         continue;
1650                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1651                 if (btrfs_file_extent_type(leaf, fi) ==
1652                     BTRFS_FILE_EXTENT_INLINE)
1653                         continue;
1654                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1655                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1656                 if (bytenr == 0)
1657                         continue;
1658                 if (!in_block_group(bytenr, rc->block_group))
1659                         continue;
1660
1661                 /*
1662                  * if we are modifying block in fs tree, wait for readpage
1663                  * to complete and drop the extent cache
1664                  */
1665                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1666                         if (first) {
1667                                 inode = find_next_inode(root, key.objectid);
1668                                 first = 0;
1669                         } else if (inode && btrfs_ino(BTRFS_I(inode)) < key.objectid) {
1670                                 btrfs_add_delayed_iput(inode);
1671                                 inode = find_next_inode(root, key.objectid);
1672                         }
1673                         if (inode && btrfs_ino(BTRFS_I(inode)) == key.objectid) {
1674                                 end = key.offset +
1675                                       btrfs_file_extent_num_bytes(leaf, fi);
1676                                 WARN_ON(!IS_ALIGNED(key.offset,
1677                                                     fs_info->sectorsize));
1678                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
1679                                 end--;
1680                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1681                                                       key.offset, end);
1682                                 if (!ret)
1683                                         continue;
1684
1685                                 btrfs_drop_extent_cache(BTRFS_I(inode),
1686                                                 key.offset,     end, 1);
1687                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1688                                               key.offset, end);
1689                         }
1690                 }
1691
1692                 ret = get_new_location(rc->data_inode, &new_bytenr,
1693                                        bytenr, num_bytes);
1694                 if (ret) {
1695                         /*
1696                          * Don't have to abort since we've not changed anything
1697                          * in the file extent yet.
1698                          */
1699                         break;
1700                 }
1701
1702                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1703                 dirty = 1;
1704
1705                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1706                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1707                                            num_bytes, parent,
1708                                            btrfs_header_owner(leaf),
1709                                            key.objectid, key.offset);
1710                 if (ret) {
1711                         btrfs_abort_transaction(trans, ret);
1712                         break;
1713                 }
1714
1715                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1716                                         parent, btrfs_header_owner(leaf),
1717                                         key.objectid, key.offset);
1718                 if (ret) {
1719                         btrfs_abort_transaction(trans, ret);
1720                         break;
1721                 }
1722         }
1723         if (dirty)
1724                 btrfs_mark_buffer_dirty(leaf);
1725         if (inode)
1726                 btrfs_add_delayed_iput(inode);
1727         return ret;
1728 }
1729
1730 static noinline_for_stack
1731 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1732                      struct btrfs_path *path, int level)
1733 {
1734         struct btrfs_disk_key key1;
1735         struct btrfs_disk_key key2;
1736         btrfs_node_key(eb, &key1, slot);
1737         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1738         return memcmp(&key1, &key2, sizeof(key1));
1739 }
1740
1741 /*
1742  * try to replace tree blocks in fs tree with the new blocks
1743  * in reloc tree. tree blocks haven't been modified since the
1744  * reloc tree was create can be replaced.
1745  *
1746  * if a block was replaced, level of the block + 1 is returned.
1747  * if no block got replaced, 0 is returned. if there are other
1748  * errors, a negative error number is returned.
1749  */
1750 static noinline_for_stack
1751 int replace_path(struct btrfs_trans_handle *trans, struct reloc_control *rc,
1752                  struct btrfs_root *dest, struct btrfs_root *src,
1753                  struct btrfs_path *path, struct btrfs_key *next_key,
1754                  int lowest_level, int max_level)
1755 {
1756         struct btrfs_fs_info *fs_info = dest->fs_info;
1757         struct extent_buffer *eb;
1758         struct extent_buffer *parent;
1759         struct btrfs_key key;
1760         u64 old_bytenr;
1761         u64 new_bytenr;
1762         u64 old_ptr_gen;
1763         u64 new_ptr_gen;
1764         u64 last_snapshot;
1765         u32 blocksize;
1766         int cow = 0;
1767         int level;
1768         int ret;
1769         int slot;
1770
1771         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1772         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1773
1774         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1775 again:
1776         slot = path->slots[lowest_level];
1777         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1778
1779         eb = btrfs_lock_root_node(dest);
1780         btrfs_set_lock_blocking_write(eb);
1781         level = btrfs_header_level(eb);
1782
1783         if (level < lowest_level) {
1784                 btrfs_tree_unlock(eb);
1785                 free_extent_buffer(eb);
1786                 return 0;
1787         }
1788
1789         if (cow) {
1790                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1791                 BUG_ON(ret);
1792         }
1793         btrfs_set_lock_blocking_write(eb);
1794
1795         if (next_key) {
1796                 next_key->objectid = (u64)-1;
1797                 next_key->type = (u8)-1;
1798                 next_key->offset = (u64)-1;
1799         }
1800
1801         parent = eb;
1802         while (1) {
1803                 struct btrfs_key first_key;
1804
1805                 level = btrfs_header_level(parent);
1806                 BUG_ON(level < lowest_level);
1807
1808                 ret = btrfs_bin_search(parent, &key, level, &slot);
1809                 if (ret < 0)
1810                         break;
1811                 if (ret && slot > 0)
1812                         slot--;
1813
1814                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1815                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1816
1817                 old_bytenr = btrfs_node_blockptr(parent, slot);
1818                 blocksize = fs_info->nodesize;
1819                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1820                 btrfs_node_key_to_cpu(parent, &first_key, slot);
1821
1822                 if (level <= max_level) {
1823                         eb = path->nodes[level];
1824                         new_bytenr = btrfs_node_blockptr(eb,
1825                                                         path->slots[level]);
1826                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1827                                                         path->slots[level]);
1828                 } else {
1829                         new_bytenr = 0;
1830                         new_ptr_gen = 0;
1831                 }
1832
1833                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1834                         ret = level;
1835                         break;
1836                 }
1837
1838                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1839                     memcmp_node_keys(parent, slot, path, level)) {
1840                         if (level <= lowest_level) {
1841                                 ret = 0;
1842                                 break;
1843                         }
1844
1845                         eb = read_tree_block(fs_info, old_bytenr, old_ptr_gen,
1846                                              level - 1, &first_key);
1847                         if (IS_ERR(eb)) {
1848                                 ret = PTR_ERR(eb);
1849                                 break;
1850                         } else if (!extent_buffer_uptodate(eb)) {
1851                                 ret = -EIO;
1852                                 free_extent_buffer(eb);
1853                                 break;
1854                         }
1855                         btrfs_tree_lock(eb);
1856                         if (cow) {
1857                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1858                                                       slot, &eb);
1859                                 BUG_ON(ret);
1860                         }
1861                         btrfs_set_lock_blocking_write(eb);
1862
1863                         btrfs_tree_unlock(parent);
1864                         free_extent_buffer(parent);
1865
1866                         parent = eb;
1867                         continue;
1868                 }
1869
1870                 if (!cow) {
1871                         btrfs_tree_unlock(parent);
1872                         free_extent_buffer(parent);
1873                         cow = 1;
1874                         goto again;
1875                 }
1876
1877                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1878                                       path->slots[level]);
1879                 btrfs_release_path(path);
1880
1881                 path->lowest_level = level;
1882                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1883                 path->lowest_level = 0;
1884                 BUG_ON(ret);
1885
1886                 /*
1887                  * Info qgroup to trace both subtrees.
1888                  *
1889                  * We must trace both trees.
1890                  * 1) Tree reloc subtree
1891                  *    If not traced, we will leak data numbers
1892                  * 2) Fs subtree
1893                  *    If not traced, we will double count old data
1894                  *
1895                  * We don't scan the subtree right now, but only record
1896                  * the swapped tree blocks.
1897                  * The real subtree rescan is delayed until we have new
1898                  * CoW on the subtree root node before transaction commit.
1899                  */
1900                 ret = btrfs_qgroup_add_swapped_blocks(trans, dest,
1901                                 rc->block_group, parent, slot,
1902                                 path->nodes[level], path->slots[level],
1903                                 last_snapshot);
1904                 if (ret < 0)
1905                         break;
1906                 /*
1907                  * swap blocks in fs tree and reloc tree.
1908                  */
1909                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1910                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1911                 btrfs_mark_buffer_dirty(parent);
1912
1913                 btrfs_set_node_blockptr(path->nodes[level],
1914                                         path->slots[level], old_bytenr);
1915                 btrfs_set_node_ptr_generation(path->nodes[level],
1916                                               path->slots[level], old_ptr_gen);
1917                 btrfs_mark_buffer_dirty(path->nodes[level]);
1918
1919                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr,
1920                                         blocksize, path->nodes[level]->start,
1921                                         src->root_key.objectid, level - 1, 0);
1922                 BUG_ON(ret);
1923                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr,
1924                                         blocksize, 0, dest->root_key.objectid,
1925                                         level - 1, 0);
1926                 BUG_ON(ret);
1927
1928                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1929                                         path->nodes[level]->start,
1930                                         src->root_key.objectid, level - 1, 0);
1931                 BUG_ON(ret);
1932
1933                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1934                                         0, dest->root_key.objectid, level - 1,
1935                                         0);
1936                 BUG_ON(ret);
1937
1938                 btrfs_unlock_up_safe(path, 0);
1939
1940                 ret = level;
1941                 break;
1942         }
1943         btrfs_tree_unlock(parent);
1944         free_extent_buffer(parent);
1945         return ret;
1946 }
1947
1948 /*
1949  * helper to find next relocated block in reloc tree
1950  */
1951 static noinline_for_stack
1952 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1953                        int *level)
1954 {
1955         struct extent_buffer *eb;
1956         int i;
1957         u64 last_snapshot;
1958         u32 nritems;
1959
1960         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1961
1962         for (i = 0; i < *level; i++) {
1963                 free_extent_buffer(path->nodes[i]);
1964                 path->nodes[i] = NULL;
1965         }
1966
1967         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1968                 eb = path->nodes[i];
1969                 nritems = btrfs_header_nritems(eb);
1970                 while (path->slots[i] + 1 < nritems) {
1971                         path->slots[i]++;
1972                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1973                             last_snapshot)
1974                                 continue;
1975
1976                         *level = i;
1977                         return 0;
1978                 }
1979                 free_extent_buffer(path->nodes[i]);
1980                 path->nodes[i] = NULL;
1981         }
1982         return 1;
1983 }
1984
1985 /*
1986  * walk down reloc tree to find relocated block of lowest level
1987  */
1988 static noinline_for_stack
1989 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1990                          int *level)
1991 {
1992         struct btrfs_fs_info *fs_info = root->fs_info;
1993         struct extent_buffer *eb = NULL;
1994         int i;
1995         u64 bytenr;
1996         u64 ptr_gen = 0;
1997         u64 last_snapshot;
1998         u32 nritems;
1999
2000         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
2001
2002         for (i = *level; i > 0; i--) {
2003                 struct btrfs_key first_key;
2004
2005                 eb = path->nodes[i];
2006                 nritems = btrfs_header_nritems(eb);
2007                 while (path->slots[i] < nritems) {
2008                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
2009                         if (ptr_gen > last_snapshot)
2010                                 break;
2011                         path->slots[i]++;
2012                 }
2013                 if (path->slots[i] >= nritems) {
2014                         if (i == *level)
2015                                 break;
2016                         *level = i + 1;
2017                         return 0;
2018                 }
2019                 if (i == 1) {
2020                         *level = i;
2021                         return 0;
2022                 }
2023
2024                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2025                 btrfs_node_key_to_cpu(eb, &first_key, path->slots[i]);
2026                 eb = read_tree_block(fs_info, bytenr, ptr_gen, i - 1,
2027                                      &first_key);
2028                 if (IS_ERR(eb)) {
2029                         return PTR_ERR(eb);
2030                 } else if (!extent_buffer_uptodate(eb)) {
2031                         free_extent_buffer(eb);
2032                         return -EIO;
2033                 }
2034                 BUG_ON(btrfs_header_level(eb) != i - 1);
2035                 path->nodes[i - 1] = eb;
2036                 path->slots[i - 1] = 0;
2037         }
2038         return 1;
2039 }
2040
2041 /*
2042  * invalidate extent cache for file extents whose key in range of
2043  * [min_key, max_key)
2044  */
2045 static int invalidate_extent_cache(struct btrfs_root *root,
2046                                    struct btrfs_key *min_key,
2047                                    struct btrfs_key *max_key)
2048 {
2049         struct btrfs_fs_info *fs_info = root->fs_info;
2050         struct inode *inode = NULL;
2051         u64 objectid;
2052         u64 start, end;
2053         u64 ino;
2054
2055         objectid = min_key->objectid;
2056         while (1) {
2057                 cond_resched();
2058                 iput(inode);
2059
2060                 if (objectid > max_key->objectid)
2061                         break;
2062
2063                 inode = find_next_inode(root, objectid);
2064                 if (!inode)
2065                         break;
2066                 ino = btrfs_ino(BTRFS_I(inode));
2067
2068                 if (ino > max_key->objectid) {
2069                         iput(inode);
2070                         break;
2071                 }
2072
2073                 objectid = ino + 1;
2074                 if (!S_ISREG(inode->i_mode))
2075                         continue;
2076
2077                 if (unlikely(min_key->objectid == ino)) {
2078                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2079                                 continue;
2080                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2081                                 start = 0;
2082                         else {
2083                                 start = min_key->offset;
2084                                 WARN_ON(!IS_ALIGNED(start, fs_info->sectorsize));
2085                         }
2086                 } else {
2087                         start = 0;
2088                 }
2089
2090                 if (unlikely(max_key->objectid == ino)) {
2091                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2092                                 continue;
2093                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2094                                 end = (u64)-1;
2095                         } else {
2096                                 if (max_key->offset == 0)
2097                                         continue;
2098                                 end = max_key->offset;
2099                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
2100                                 end--;
2101                         }
2102                 } else {
2103                         end = (u64)-1;
2104                 }
2105
2106                 /* the lock_extent waits for readpage to complete */
2107                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2108                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 1);
2109                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2110         }
2111         return 0;
2112 }
2113
2114 static int find_next_key(struct btrfs_path *path, int level,
2115                          struct btrfs_key *key)
2116
2117 {
2118         while (level < BTRFS_MAX_LEVEL) {
2119                 if (!path->nodes[level])
2120                         break;
2121                 if (path->slots[level] + 1 <
2122                     btrfs_header_nritems(path->nodes[level])) {
2123                         btrfs_node_key_to_cpu(path->nodes[level], key,
2124                                               path->slots[level] + 1);
2125                         return 0;
2126                 }
2127                 level++;
2128         }
2129         return 1;
2130 }
2131
2132 /*
2133  * Insert current subvolume into reloc_control::dirty_subvol_roots
2134  */
2135 static void insert_dirty_subvol(struct btrfs_trans_handle *trans,
2136                                 struct reloc_control *rc,
2137                                 struct btrfs_root *root)
2138 {
2139         struct btrfs_root *reloc_root = root->reloc_root;
2140         struct btrfs_root_item *reloc_root_item;
2141
2142         /* @root must be a subvolume tree root with a valid reloc tree */
2143         ASSERT(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
2144         ASSERT(reloc_root);
2145
2146         reloc_root_item = &reloc_root->root_item;
2147         memset(&reloc_root_item->drop_progress, 0,
2148                 sizeof(reloc_root_item->drop_progress));
2149         reloc_root_item->drop_level = 0;
2150         btrfs_set_root_refs(reloc_root_item, 0);
2151         btrfs_update_reloc_root(trans, root);
2152
2153         if (list_empty(&root->reloc_dirty_list)) {
2154                 btrfs_grab_fs_root(root);
2155                 list_add_tail(&root->reloc_dirty_list, &rc->dirty_subvol_roots);
2156         }
2157 }
2158
2159 static int clean_dirty_subvols(struct reloc_control *rc)
2160 {
2161         struct btrfs_root *root;
2162         struct btrfs_root *next;
2163         int ret = 0;
2164
2165         list_for_each_entry_safe(root, next, &rc->dirty_subvol_roots,
2166                                  reloc_dirty_list) {
2167                 struct btrfs_root *reloc_root = root->reloc_root;
2168
2169                 clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
2170                 list_del_init(&root->reloc_dirty_list);
2171                 root->reloc_root = NULL;
2172                 if (reloc_root) {
2173                         int ret2;
2174
2175                         ret2 = btrfs_drop_snapshot(reloc_root, NULL, 0, 1);
2176                         if (ret2 < 0 && !ret)
2177                                 ret = ret2;
2178                 }
2179                 btrfs_put_fs_root(root);
2180         }
2181         return ret;
2182 }
2183
2184 /*
2185  * merge the relocated tree blocks in reloc tree with corresponding
2186  * fs tree.
2187  */
2188 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2189                                                struct btrfs_root *root)
2190 {
2191         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2192         struct btrfs_key key;
2193         struct btrfs_key next_key;
2194         struct btrfs_trans_handle *trans = NULL;
2195         struct btrfs_root *reloc_root;
2196         struct btrfs_root_item *root_item;
2197         struct btrfs_path *path;
2198         struct extent_buffer *leaf;
2199         int level;
2200         int max_level;
2201         int replaced = 0;
2202         int ret;
2203         int err = 0;
2204         u32 min_reserved;
2205
2206         path = btrfs_alloc_path();
2207         if (!path)
2208                 return -ENOMEM;
2209         path->reada = READA_FORWARD;
2210
2211         reloc_root = root->reloc_root;
2212         root_item = &reloc_root->root_item;
2213
2214         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2215                 level = btrfs_root_level(root_item);
2216                 extent_buffer_get(reloc_root->node);
2217                 path->nodes[level] = reloc_root->node;
2218                 path->slots[level] = 0;
2219         } else {
2220                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2221
2222                 level = root_item->drop_level;
2223                 BUG_ON(level == 0);
2224                 path->lowest_level = level;
2225                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2226                 path->lowest_level = 0;
2227                 if (ret < 0) {
2228                         btrfs_free_path(path);
2229                         return ret;
2230                 }
2231
2232                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2233                                       path->slots[level]);
2234                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2235
2236                 btrfs_unlock_up_safe(path, 0);
2237         }
2238
2239         min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2240         memset(&next_key, 0, sizeof(next_key));
2241
2242         while (1) {
2243                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2244                                              BTRFS_RESERVE_FLUSH_ALL);
2245                 if (ret) {
2246                         err = ret;
2247                         goto out;
2248                 }
2249                 trans = btrfs_start_transaction(root, 0);
2250                 if (IS_ERR(trans)) {
2251                         err = PTR_ERR(trans);
2252                         trans = NULL;
2253                         goto out;
2254                 }
2255                 trans->block_rsv = rc->block_rsv;
2256
2257                 replaced = 0;
2258                 max_level = level;
2259
2260                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2261                 if (ret < 0) {
2262                         err = ret;
2263                         goto out;
2264                 }
2265                 if (ret > 0)
2266                         break;
2267
2268                 if (!find_next_key(path, level, &key) &&
2269                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2270                         ret = 0;
2271                 } else {
2272                         ret = replace_path(trans, rc, root, reloc_root, path,
2273                                            &next_key, level, max_level);
2274                 }
2275                 if (ret < 0) {
2276                         err = ret;
2277                         goto out;
2278                 }
2279
2280                 if (ret > 0) {
2281                         level = ret;
2282                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2283                                               path->slots[level]);
2284                         replaced = 1;
2285                 }
2286
2287                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2288                 if (ret > 0)
2289                         break;
2290
2291                 BUG_ON(level == 0);
2292                 /*
2293                  * save the merging progress in the drop_progress.
2294                  * this is OK since root refs == 1 in this case.
2295                  */
2296                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2297                                path->slots[level]);
2298                 root_item->drop_level = level;
2299
2300                 btrfs_end_transaction_throttle(trans);
2301                 trans = NULL;
2302
2303                 btrfs_btree_balance_dirty(fs_info);
2304
2305                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2306                         invalidate_extent_cache(root, &key, &next_key);
2307         }
2308
2309         /*
2310          * handle the case only one block in the fs tree need to be
2311          * relocated and the block is tree root.
2312          */
2313         leaf = btrfs_lock_root_node(root);
2314         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2315         btrfs_tree_unlock(leaf);
2316         free_extent_buffer(leaf);
2317         if (ret < 0)
2318                 err = ret;
2319 out:
2320         btrfs_free_path(path);
2321
2322         if (err == 0)
2323                 insert_dirty_subvol(trans, rc, root);
2324
2325         if (trans)
2326                 btrfs_end_transaction_throttle(trans);
2327
2328         btrfs_btree_balance_dirty(fs_info);
2329
2330         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2331                 invalidate_extent_cache(root, &key, &next_key);
2332
2333         return err;
2334 }
2335
2336 static noinline_for_stack
2337 int prepare_to_merge(struct reloc_control *rc, int err)
2338 {
2339         struct btrfs_root *root = rc->extent_root;
2340         struct btrfs_fs_info *fs_info = root->fs_info;
2341         struct btrfs_root *reloc_root;
2342         struct btrfs_trans_handle *trans;
2343         LIST_HEAD(reloc_roots);
2344         u64 num_bytes = 0;
2345         int ret;
2346
2347         mutex_lock(&fs_info->reloc_mutex);
2348         rc->merging_rsv_size += fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2349         rc->merging_rsv_size += rc->nodes_relocated * 2;
2350         mutex_unlock(&fs_info->reloc_mutex);
2351
2352 again:
2353         if (!err) {
2354                 num_bytes = rc->merging_rsv_size;
2355                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2356                                           BTRFS_RESERVE_FLUSH_ALL);
2357                 if (ret)
2358                         err = ret;
2359         }
2360
2361         trans = btrfs_join_transaction(rc->extent_root);
2362         if (IS_ERR(trans)) {
2363                 if (!err)
2364                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2365                                                 num_bytes);
2366                 return PTR_ERR(trans);
2367         }
2368
2369         if (!err) {
2370                 if (num_bytes != rc->merging_rsv_size) {
2371                         btrfs_end_transaction(trans);
2372                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2373                                                 num_bytes);
2374                         goto again;
2375                 }
2376         }
2377
2378         rc->merge_reloc_tree = 1;
2379
2380         while (!list_empty(&rc->reloc_roots)) {
2381                 reloc_root = list_entry(rc->reloc_roots.next,
2382                                         struct btrfs_root, root_list);
2383                 list_del_init(&reloc_root->root_list);
2384
2385                 root = read_fs_root(fs_info, reloc_root->root_key.offset);
2386                 BUG_ON(IS_ERR(root));
2387                 BUG_ON(root->reloc_root != reloc_root);
2388
2389                 /*
2390                  * set reference count to 1, so btrfs_recover_relocation
2391                  * knows it should resumes merging
2392                  */
2393                 if (!err)
2394                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2395                 btrfs_update_reloc_root(trans, root);
2396
2397                 list_add(&reloc_root->root_list, &reloc_roots);
2398         }
2399
2400         list_splice(&reloc_roots, &rc->reloc_roots);
2401
2402         if (!err)
2403                 btrfs_commit_transaction(trans);
2404         else
2405                 btrfs_end_transaction(trans);
2406         return err;
2407 }
2408
2409 static noinline_for_stack
2410 void free_reloc_roots(struct list_head *list)
2411 {
2412         struct btrfs_root *reloc_root;
2413
2414         while (!list_empty(list)) {
2415                 reloc_root = list_entry(list->next, struct btrfs_root,
2416                                         root_list);
2417                 __del_reloc_root(reloc_root);
2418                 free_extent_buffer(reloc_root->node);
2419                 free_extent_buffer(reloc_root->commit_root);
2420                 reloc_root->node = NULL;
2421                 reloc_root->commit_root = NULL;
2422         }
2423 }
2424
2425 static noinline_for_stack
2426 void merge_reloc_roots(struct reloc_control *rc)
2427 {
2428         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2429         struct btrfs_root *root;
2430         struct btrfs_root *reloc_root;
2431         LIST_HEAD(reloc_roots);
2432         int found = 0;
2433         int ret = 0;
2434 again:
2435         root = rc->extent_root;
2436
2437         /*
2438          * this serializes us with btrfs_record_root_in_transaction,
2439          * we have to make sure nobody is in the middle of
2440          * adding their roots to the list while we are
2441          * doing this splice
2442          */
2443         mutex_lock(&fs_info->reloc_mutex);
2444         list_splice_init(&rc->reloc_roots, &reloc_roots);
2445         mutex_unlock(&fs_info->reloc_mutex);
2446
2447         while (!list_empty(&reloc_roots)) {
2448                 found = 1;
2449                 reloc_root = list_entry(reloc_roots.next,
2450                                         struct btrfs_root, root_list);
2451
2452                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2453                         root = read_fs_root(fs_info,
2454                                             reloc_root->root_key.offset);
2455                         BUG_ON(IS_ERR(root));
2456                         BUG_ON(root->reloc_root != reloc_root);
2457
2458                         ret = merge_reloc_root(rc, root);
2459                         if (ret) {
2460                                 if (list_empty(&reloc_root->root_list))
2461                                         list_add_tail(&reloc_root->root_list,
2462                                                       &reloc_roots);
2463                                 goto out;
2464                         }
2465                 } else {
2466                         list_del_init(&reloc_root->root_list);
2467                 }
2468         }
2469
2470         if (found) {
2471                 found = 0;
2472                 goto again;
2473         }
2474 out:
2475         if (ret) {
2476                 btrfs_handle_fs_error(fs_info, ret, NULL);
2477                 if (!list_empty(&reloc_roots))
2478                         free_reloc_roots(&reloc_roots);
2479
2480                 /* new reloc root may be added */
2481                 mutex_lock(&fs_info->reloc_mutex);
2482                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2483                 mutex_unlock(&fs_info->reloc_mutex);
2484                 if (!list_empty(&reloc_roots))
2485                         free_reloc_roots(&reloc_roots);
2486         }
2487
2488         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2489 }
2490
2491 static void free_block_list(struct rb_root *blocks)
2492 {
2493         struct tree_block *block;
2494         struct rb_node *rb_node;
2495         while ((rb_node = rb_first(blocks))) {
2496                 block = rb_entry(rb_node, struct tree_block, rb_node);
2497                 rb_erase(rb_node, blocks);
2498                 kfree(block);
2499         }
2500 }
2501
2502 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2503                                       struct btrfs_root *reloc_root)
2504 {
2505         struct btrfs_fs_info *fs_info = reloc_root->fs_info;
2506         struct btrfs_root *root;
2507
2508         if (reloc_root->last_trans == trans->transid)
2509                 return 0;
2510
2511         root = read_fs_root(fs_info, reloc_root->root_key.offset);
2512         BUG_ON(IS_ERR(root));
2513         BUG_ON(root->reloc_root != reloc_root);
2514
2515         return btrfs_record_root_in_trans(trans, root);
2516 }
2517
2518 static noinline_for_stack
2519 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2520                                      struct reloc_control *rc,
2521                                      struct backref_node *node,
2522                                      struct backref_edge *edges[])
2523 {
2524         struct backref_node *next;
2525         struct btrfs_root *root;
2526         int index = 0;
2527
2528         next = node;
2529         while (1) {
2530                 cond_resched();
2531                 next = walk_up_backref(next, edges, &index);
2532                 root = next->root;
2533                 BUG_ON(!root);
2534                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2535
2536                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2537                         record_reloc_root_in_trans(trans, root);
2538                         break;
2539                 }
2540
2541                 btrfs_record_root_in_trans(trans, root);
2542                 root = root->reloc_root;
2543
2544                 if (next->new_bytenr != root->node->start) {
2545                         BUG_ON(next->new_bytenr);
2546                         BUG_ON(!list_empty(&next->list));
2547                         next->new_bytenr = root->node->start;
2548                         next->root = root;
2549                         list_add_tail(&next->list,
2550                                       &rc->backref_cache.changed);
2551                         __mark_block_processed(rc, next);
2552                         break;
2553                 }
2554
2555                 WARN_ON(1);
2556                 root = NULL;
2557                 next = walk_down_backref(edges, &index);
2558                 if (!next || next->level <= node->level)
2559                         break;
2560         }
2561         if (!root)
2562                 return NULL;
2563
2564         next = node;
2565         /* setup backref node path for btrfs_reloc_cow_block */
2566         while (1) {
2567                 rc->backref_cache.path[next->level] = next;
2568                 if (--index < 0)
2569                         break;
2570                 next = edges[index]->node[UPPER];
2571         }
2572         return root;
2573 }
2574
2575 /*
2576  * select a tree root for relocation. return NULL if the block
2577  * is reference counted. we should use do_relocation() in this
2578  * case. return a tree root pointer if the block isn't reference
2579  * counted. return -ENOENT if the block is root of reloc tree.
2580  */
2581 static noinline_for_stack
2582 struct btrfs_root *select_one_root(struct backref_node *node)
2583 {
2584         struct backref_node *next;
2585         struct btrfs_root *root;
2586         struct btrfs_root *fs_root = NULL;
2587         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2588         int index = 0;
2589
2590         next = node;
2591         while (1) {
2592                 cond_resched();
2593                 next = walk_up_backref(next, edges, &index);
2594                 root = next->root;
2595                 BUG_ON(!root);
2596
2597                 /* no other choice for non-references counted tree */
2598                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2599                         return root;
2600
2601                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2602                         fs_root = root;
2603
2604                 if (next != node)
2605                         return NULL;
2606
2607                 next = walk_down_backref(edges, &index);
2608                 if (!next || next->level <= node->level)
2609                         break;
2610         }
2611
2612         if (!fs_root)
2613                 return ERR_PTR(-ENOENT);
2614         return fs_root;
2615 }
2616
2617 static noinline_for_stack
2618 u64 calcu_metadata_size(struct reloc_control *rc,
2619                         struct backref_node *node, int reserve)
2620 {
2621         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2622         struct backref_node *next = node;
2623         struct backref_edge *edge;
2624         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2625         u64 num_bytes = 0;
2626         int index = 0;
2627
2628         BUG_ON(reserve && node->processed);
2629
2630         while (next) {
2631                 cond_resched();
2632                 while (1) {
2633                         if (next->processed && (reserve || next != node))
2634                                 break;
2635
2636                         num_bytes += fs_info->nodesize;
2637
2638                         if (list_empty(&next->upper))
2639                                 break;
2640
2641                         edge = list_entry(next->upper.next,
2642                                           struct backref_edge, list[LOWER]);
2643                         edges[index++] = edge;
2644                         next = edge->node[UPPER];
2645                 }
2646                 next = walk_down_backref(edges, &index);
2647         }
2648         return num_bytes;
2649 }
2650
2651 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2652                                   struct reloc_control *rc,
2653                                   struct backref_node *node)
2654 {
2655         struct btrfs_root *root = rc->extent_root;
2656         struct btrfs_fs_info *fs_info = root->fs_info;
2657         u64 num_bytes;
2658         int ret;
2659         u64 tmp;
2660
2661         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2662
2663         trans->block_rsv = rc->block_rsv;
2664         rc->reserved_bytes += num_bytes;
2665
2666         /*
2667          * We are under a transaction here so we can only do limited flushing.
2668          * If we get an enospc just kick back -EAGAIN so we know to drop the
2669          * transaction and try to refill when we can flush all the things.
2670          */
2671         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2672                                 BTRFS_RESERVE_FLUSH_LIMIT);
2673         if (ret) {
2674                 tmp = fs_info->nodesize * RELOCATION_RESERVED_NODES;
2675                 while (tmp <= rc->reserved_bytes)
2676                         tmp <<= 1;
2677                 /*
2678                  * only one thread can access block_rsv at this point,
2679                  * so we don't need hold lock to protect block_rsv.
2680                  * we expand more reservation size here to allow enough
2681                  * space for relocation and we will return earlier in
2682                  * enospc case.
2683                  */
2684                 rc->block_rsv->size = tmp + fs_info->nodesize *
2685                                       RELOCATION_RESERVED_NODES;
2686                 return -EAGAIN;
2687         }
2688
2689         return 0;
2690 }
2691
2692 /*
2693  * relocate a block tree, and then update pointers in upper level
2694  * blocks that reference the block to point to the new location.
2695  *
2696  * if called by link_to_upper, the block has already been relocated.
2697  * in that case this function just updates pointers.
2698  */
2699 static int do_relocation(struct btrfs_trans_handle *trans,
2700                          struct reloc_control *rc,
2701                          struct backref_node *node,
2702                          struct btrfs_key *key,
2703                          struct btrfs_path *path, int lowest)
2704 {
2705         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2706         struct backref_node *upper;
2707         struct backref_edge *edge;
2708         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2709         struct btrfs_root *root;
2710         struct extent_buffer *eb;
2711         u32 blocksize;
2712         u64 bytenr;
2713         u64 generation;
2714         int slot;
2715         int ret;
2716         int err = 0;
2717
2718         BUG_ON(lowest && node->eb);
2719
2720         path->lowest_level = node->level + 1;
2721         rc->backref_cache.path[node->level] = node;
2722         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2723                 struct btrfs_key first_key;
2724
2725                 cond_resched();
2726
2727                 upper = edge->node[UPPER];
2728                 root = select_reloc_root(trans, rc, upper, edges);
2729                 BUG_ON(!root);
2730
2731                 if (upper->eb && !upper->locked) {
2732                         if (!lowest) {
2733                                 ret = btrfs_bin_search(upper->eb, key,
2734                                                        upper->level, &slot);
2735                                 if (ret < 0) {
2736                                         err = ret;
2737                                         goto next;
2738                                 }
2739                                 BUG_ON(ret);
2740                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2741                                 if (node->eb->start == bytenr)
2742                                         goto next;
2743                         }
2744                         drop_node_buffer(upper);
2745                 }
2746
2747                 if (!upper->eb) {
2748                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2749                         if (ret) {
2750                                 if (ret < 0)
2751                                         err = ret;
2752                                 else
2753                                         err = -ENOENT;
2754
2755                                 btrfs_release_path(path);
2756                                 break;
2757                         }
2758
2759                         if (!upper->eb) {
2760                                 upper->eb = path->nodes[upper->level];
2761                                 path->nodes[upper->level] = NULL;
2762                         } else {
2763                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2764                         }
2765
2766                         upper->locked = 1;
2767                         path->locks[upper->level] = 0;
2768
2769                         slot = path->slots[upper->level];
2770                         btrfs_release_path(path);
2771                 } else {
2772                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2773                                                &slot);
2774                         if (ret < 0) {
2775                                 err = ret;
2776                                 goto next;
2777                         }
2778                         BUG_ON(ret);
2779                 }
2780
2781                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2782                 if (lowest) {
2783                         if (bytenr != node->bytenr) {
2784                                 btrfs_err(root->fs_info,
2785                 "lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu",
2786                                           bytenr, node->bytenr, slot,
2787                                           upper->eb->start);
2788                                 err = -EIO;
2789                                 goto next;
2790                         }
2791                 } else {
2792                         if (node->eb->start == bytenr)
2793                                 goto next;
2794                 }
2795
2796                 blocksize = root->fs_info->nodesize;
2797                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2798                 btrfs_node_key_to_cpu(upper->eb, &first_key, slot);
2799                 eb = read_tree_block(fs_info, bytenr, generation,
2800                                      upper->level - 1, &first_key);
2801                 if (IS_ERR(eb)) {
2802                         err = PTR_ERR(eb);
2803                         goto next;
2804                 } else if (!extent_buffer_uptodate(eb)) {
2805                         free_extent_buffer(eb);
2806                         err = -EIO;
2807                         goto next;
2808                 }
2809                 btrfs_tree_lock(eb);
2810                 btrfs_set_lock_blocking_write(eb);
2811
2812                 if (!node->eb) {
2813                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2814                                               slot, &eb);
2815                         btrfs_tree_unlock(eb);
2816                         free_extent_buffer(eb);
2817                         if (ret < 0) {
2818                                 err = ret;
2819                                 goto next;
2820                         }
2821                         BUG_ON(node->eb != eb);
2822                 } else {
2823                         btrfs_set_node_blockptr(upper->eb, slot,
2824                                                 node->eb->start);
2825                         btrfs_set_node_ptr_generation(upper->eb, slot,
2826                                                       trans->transid);
2827                         btrfs_mark_buffer_dirty(upper->eb);
2828
2829                         ret = btrfs_inc_extent_ref(trans, root,
2830                                                 node->eb->start, blocksize,
2831                                                 upper->eb->start,
2832                                                 btrfs_header_owner(upper->eb),
2833                                                 node->level, 0);
2834                         BUG_ON(ret);
2835
2836                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2837                         BUG_ON(ret);
2838                 }
2839 next:
2840                 if (!upper->pending)
2841                         drop_node_buffer(upper);
2842                 else
2843                         unlock_node_buffer(upper);
2844                 if (err)
2845                         break;
2846         }
2847
2848         if (!err && node->pending) {
2849                 drop_node_buffer(node);
2850                 list_move_tail(&node->list, &rc->backref_cache.changed);
2851                 node->pending = 0;
2852         }
2853
2854         path->lowest_level = 0;
2855         BUG_ON(err == -ENOSPC);
2856         return err;
2857 }
2858
2859 static int link_to_upper(struct btrfs_trans_handle *trans,
2860                          struct reloc_control *rc,
2861                          struct backref_node *node,
2862                          struct btrfs_path *path)
2863 {
2864         struct btrfs_key key;
2865
2866         btrfs_node_key_to_cpu(node->eb, &key, 0);
2867         return do_relocation(trans, rc, node, &key, path, 0);
2868 }
2869
2870 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2871                                 struct reloc_control *rc,
2872                                 struct btrfs_path *path, int err)
2873 {
2874         LIST_HEAD(list);
2875         struct backref_cache *cache = &rc->backref_cache;
2876         struct backref_node *node;
2877         int level;
2878         int ret;
2879
2880         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2881                 while (!list_empty(&cache->pending[level])) {
2882                         node = list_entry(cache->pending[level].next,
2883                                           struct backref_node, list);
2884                         list_move_tail(&node->list, &list);
2885                         BUG_ON(!node->pending);
2886
2887                         if (!err) {
2888                                 ret = link_to_upper(trans, rc, node, path);
2889                                 if (ret < 0)
2890                                         err = ret;
2891                         }
2892                 }
2893                 list_splice_init(&list, &cache->pending[level]);
2894         }
2895         return err;
2896 }
2897
2898 static void mark_block_processed(struct reloc_control *rc,
2899                                  u64 bytenr, u32 blocksize)
2900 {
2901         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2902                         EXTENT_DIRTY);
2903 }
2904
2905 static void __mark_block_processed(struct reloc_control *rc,
2906                                    struct backref_node *node)
2907 {
2908         u32 blocksize;
2909         if (node->level == 0 ||
2910             in_block_group(node->bytenr, rc->block_group)) {
2911                 blocksize = rc->extent_root->fs_info->nodesize;
2912                 mark_block_processed(rc, node->bytenr, blocksize);
2913         }
2914         node->processed = 1;
2915 }
2916
2917 /*
2918  * mark a block and all blocks directly/indirectly reference the block
2919  * as processed.
2920  */
2921 static void update_processed_blocks(struct reloc_control *rc,
2922                                     struct backref_node *node)
2923 {
2924         struct backref_node *next = node;
2925         struct backref_edge *edge;
2926         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2927         int index = 0;
2928
2929         while (next) {
2930                 cond_resched();
2931                 while (1) {
2932                         if (next->processed)
2933                                 break;
2934
2935                         __mark_block_processed(rc, next);
2936
2937                         if (list_empty(&next->upper))
2938                                 break;
2939
2940                         edge = list_entry(next->upper.next,
2941                                           struct backref_edge, list[LOWER]);
2942                         edges[index++] = edge;
2943                         next = edge->node[UPPER];
2944                 }
2945                 next = walk_down_backref(edges, &index);
2946         }
2947 }
2948
2949 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2950 {
2951         u32 blocksize = rc->extent_root->fs_info->nodesize;
2952
2953         if (test_range_bit(&rc->processed_blocks, bytenr,
2954                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2955                 return 1;
2956         return 0;
2957 }
2958
2959 static int get_tree_block_key(struct btrfs_fs_info *fs_info,
2960                               struct tree_block *block)
2961 {
2962         struct extent_buffer *eb;
2963
2964         BUG_ON(block->key_ready);
2965         eb = read_tree_block(fs_info, block->bytenr, block->key.offset,
2966                              block->level, NULL);
2967         if (IS_ERR(eb)) {
2968                 return PTR_ERR(eb);
2969         } else if (!extent_buffer_uptodate(eb)) {
2970                 free_extent_buffer(eb);
2971                 return -EIO;
2972         }
2973         if (block->level == 0)
2974                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2975         else
2976                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2977         free_extent_buffer(eb);
2978         block->key_ready = 1;
2979         return 0;
2980 }
2981
2982 /*
2983  * helper function to relocate a tree block
2984  */
2985 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2986                                 struct reloc_control *rc,
2987                                 struct backref_node *node,
2988                                 struct btrfs_key *key,
2989                                 struct btrfs_path *path)
2990 {
2991         struct btrfs_root *root;
2992         int ret = 0;
2993
2994         if (!node)
2995                 return 0;
2996
2997         BUG_ON(node->processed);
2998         root = select_one_root(node);
2999         if (root == ERR_PTR(-ENOENT)) {
3000                 update_processed_blocks(rc, node);
3001                 goto out;
3002         }
3003
3004         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
3005                 ret = reserve_metadata_space(trans, rc, node);
3006                 if (ret)
3007                         goto out;
3008         }
3009
3010         if (root) {
3011                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
3012                         BUG_ON(node->new_bytenr);
3013                         BUG_ON(!list_empty(&node->list));
3014                         btrfs_record_root_in_trans(trans, root);
3015                         root = root->reloc_root;
3016                         node->new_bytenr = root->node->start;
3017                         node->root = root;
3018                         list_add_tail(&node->list, &rc->backref_cache.changed);
3019                 } else {
3020                         path->lowest_level = node->level;
3021                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
3022                         btrfs_release_path(path);
3023                         if (ret > 0)
3024                                 ret = 0;
3025                 }
3026                 if (!ret)
3027                         update_processed_blocks(rc, node);
3028         } else {
3029                 ret = do_relocation(trans, rc, node, key, path, 1);
3030         }
3031 out:
3032         if (ret || node->level == 0 || node->cowonly)
3033                 remove_backref_node(&rc->backref_cache, node);
3034         return ret;
3035 }
3036
3037 /*
3038  * relocate a list of blocks
3039  */
3040 static noinline_for_stack
3041 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
3042                          struct reloc_control *rc, struct rb_root *blocks)
3043 {
3044         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3045         struct backref_node *node;
3046         struct btrfs_path *path;
3047         struct tree_block *block;
3048         struct tree_block *next;
3049         int ret;
3050         int err = 0;
3051
3052         path = btrfs_alloc_path();
3053         if (!path) {
3054                 err = -ENOMEM;
3055                 goto out_free_blocks;
3056         }
3057
3058         /* Kick in readahead for tree blocks with missing keys */
3059         rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3060                 if (!block->key_ready)
3061                         readahead_tree_block(fs_info, block->bytenr);
3062         }
3063
3064         /* Get first keys */
3065         rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3066                 if (!block->key_ready) {
3067                         err = get_tree_block_key(fs_info, block);
3068                         if (err)
3069                                 goto out_free_path;
3070                 }
3071         }
3072
3073         /* Do tree relocation */
3074         rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3075                 node = build_backref_tree(rc, &block->key,
3076                                           block->level, block->bytenr);
3077                 if (IS_ERR(node)) {
3078                         err = PTR_ERR(node);
3079                         goto out;
3080                 }
3081
3082                 ret = relocate_tree_block(trans, rc, node, &block->key,
3083                                           path);
3084                 if (ret < 0) {
3085                         if (ret != -EAGAIN || &block->rb_node == rb_first(blocks))
3086                                 err = ret;