d60df51959f7abd5f392b5f407ab85558672d10c
[sfrench/cifs-2.6.git] / fs / btrfs / relocation.c
1 /*
2  * Copyright (C) 2009 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/sched.h>
20 #include <linux/pagemap.h>
21 #include <linux/writeback.h>
22 #include <linux/blkdev.h>
23 #include <linux/rbtree.h>
24 #include <linux/slab.h>
25 #include "ctree.h"
26 #include "disk-io.h"
27 #include "transaction.h"
28 #include "volumes.h"
29 #include "locking.h"
30 #include "btrfs_inode.h"
31 #include "async-thread.h"
32 #include "free-space-cache.h"
33 #include "inode-map.h"
34 #include "qgroup.h"
35
36 /*
37  * backref_node, mapping_node and tree_block start with this
38  */
39 struct tree_entry {
40         struct rb_node rb_node;
41         u64 bytenr;
42 };
43
44 /*
45  * present a tree block in the backref cache
46  */
47 struct backref_node {
48         struct rb_node rb_node;
49         u64 bytenr;
50
51         u64 new_bytenr;
52         /* objectid of tree block owner, can be not uptodate */
53         u64 owner;
54         /* link to pending, changed or detached list */
55         struct list_head list;
56         /* list of upper level blocks reference this block */
57         struct list_head upper;
58         /* list of child blocks in the cache */
59         struct list_head lower;
60         /* NULL if this node is not tree root */
61         struct btrfs_root *root;
62         /* extent buffer got by COW the block */
63         struct extent_buffer *eb;
64         /* level of tree block */
65         unsigned int level:8;
66         /* is the block in non-reference counted tree */
67         unsigned int cowonly:1;
68         /* 1 if no child node in the cache */
69         unsigned int lowest:1;
70         /* is the extent buffer locked */
71         unsigned int locked:1;
72         /* has the block been processed */
73         unsigned int processed:1;
74         /* have backrefs of this block been checked */
75         unsigned int checked:1;
76         /*
77          * 1 if corresponding block has been cowed but some upper
78          * level block pointers may not point to the new location
79          */
80         unsigned int pending:1;
81         /*
82          * 1 if the backref node isn't connected to any other
83          * backref node.
84          */
85         unsigned int detached:1;
86 };
87
88 /*
89  * present a block pointer in the backref cache
90  */
91 struct backref_edge {
92         struct list_head list[2];
93         struct backref_node *node[2];
94 };
95
96 #define LOWER   0
97 #define UPPER   1
98 #define RELOCATION_RESERVED_NODES       256
99
100 struct backref_cache {
101         /* red black tree of all backref nodes in the cache */
102         struct rb_root rb_root;
103         /* for passing backref nodes to btrfs_reloc_cow_block */
104         struct backref_node *path[BTRFS_MAX_LEVEL];
105         /*
106          * list of blocks that have been cowed but some block
107          * pointers in upper level blocks may not reflect the
108          * new location
109          */
110         struct list_head pending[BTRFS_MAX_LEVEL];
111         /* list of backref nodes with no child node */
112         struct list_head leaves;
113         /* list of blocks that have been cowed in current transaction */
114         struct list_head changed;
115         /* list of detached backref node. */
116         struct list_head detached;
117
118         u64 last_trans;
119
120         int nr_nodes;
121         int nr_edges;
122 };
123
124 /*
125  * map address of tree root to tree
126  */
127 struct mapping_node {
128         struct rb_node rb_node;
129         u64 bytenr;
130         void *data;
131 };
132
133 struct mapping_tree {
134         struct rb_root rb_root;
135         spinlock_t lock;
136 };
137
138 /*
139  * present a tree block to process
140  */
141 struct tree_block {
142         struct rb_node rb_node;
143         u64 bytenr;
144         struct btrfs_key key;
145         unsigned int level:8;
146         unsigned int key_ready:1;
147 };
148
149 #define MAX_EXTENTS 128
150
151 struct file_extent_cluster {
152         u64 start;
153         u64 end;
154         u64 boundary[MAX_EXTENTS];
155         unsigned int nr;
156 };
157
158 struct reloc_control {
159         /* block group to relocate */
160         struct btrfs_block_group_cache *block_group;
161         /* extent tree */
162         struct btrfs_root *extent_root;
163         /* inode for moving data */
164         struct inode *data_inode;
165
166         struct btrfs_block_rsv *block_rsv;
167
168         struct backref_cache backref_cache;
169
170         struct file_extent_cluster cluster;
171         /* tree blocks have been processed */
172         struct extent_io_tree processed_blocks;
173         /* map start of tree root to corresponding reloc tree */
174         struct mapping_tree reloc_root_tree;
175         /* list of reloc trees */
176         struct list_head reloc_roots;
177         /* size of metadata reservation for merging reloc trees */
178         u64 merging_rsv_size;
179         /* size of relocated tree nodes */
180         u64 nodes_relocated;
181         /* reserved size for block group relocation*/
182         u64 reserved_bytes;
183
184         u64 search_start;
185         u64 extents_found;
186
187         unsigned int stage:8;
188         unsigned int create_reloc_tree:1;
189         unsigned int merge_reloc_tree:1;
190         unsigned int found_file_extent:1;
191 };
192
193 /* stages of data relocation */
194 #define MOVE_DATA_EXTENTS       0
195 #define UPDATE_DATA_PTRS        1
196
197 static void remove_backref_node(struct backref_cache *cache,
198                                 struct backref_node *node);
199 static void __mark_block_processed(struct reloc_control *rc,
200                                    struct backref_node *node);
201
202 static void mapping_tree_init(struct mapping_tree *tree)
203 {
204         tree->rb_root = RB_ROOT;
205         spin_lock_init(&tree->lock);
206 }
207
208 static void backref_cache_init(struct backref_cache *cache)
209 {
210         int i;
211         cache->rb_root = RB_ROOT;
212         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
213                 INIT_LIST_HEAD(&cache->pending[i]);
214         INIT_LIST_HEAD(&cache->changed);
215         INIT_LIST_HEAD(&cache->detached);
216         INIT_LIST_HEAD(&cache->leaves);
217 }
218
219 static void backref_cache_cleanup(struct backref_cache *cache)
220 {
221         struct backref_node *node;
222         int i;
223
224         while (!list_empty(&cache->detached)) {
225                 node = list_entry(cache->detached.next,
226                                   struct backref_node, list);
227                 remove_backref_node(cache, node);
228         }
229
230         while (!list_empty(&cache->leaves)) {
231                 node = list_entry(cache->leaves.next,
232                                   struct backref_node, lower);
233                 remove_backref_node(cache, node);
234         }
235
236         cache->last_trans = 0;
237
238         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
239                 ASSERT(list_empty(&cache->pending[i]));
240         ASSERT(list_empty(&cache->changed));
241         ASSERT(list_empty(&cache->detached));
242         ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
243         ASSERT(!cache->nr_nodes);
244         ASSERT(!cache->nr_edges);
245 }
246
247 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
248 {
249         struct backref_node *node;
250
251         node = kzalloc(sizeof(*node), GFP_NOFS);
252         if (node) {
253                 INIT_LIST_HEAD(&node->list);
254                 INIT_LIST_HEAD(&node->upper);
255                 INIT_LIST_HEAD(&node->lower);
256                 RB_CLEAR_NODE(&node->rb_node);
257                 cache->nr_nodes++;
258         }
259         return node;
260 }
261
262 static void free_backref_node(struct backref_cache *cache,
263                               struct backref_node *node)
264 {
265         if (node) {
266                 cache->nr_nodes--;
267                 kfree(node);
268         }
269 }
270
271 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
272 {
273         struct backref_edge *edge;
274
275         edge = kzalloc(sizeof(*edge), GFP_NOFS);
276         if (edge)
277                 cache->nr_edges++;
278         return edge;
279 }
280
281 static void free_backref_edge(struct backref_cache *cache,
282                               struct backref_edge *edge)
283 {
284         if (edge) {
285                 cache->nr_edges--;
286                 kfree(edge);
287         }
288 }
289
290 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
291                                    struct rb_node *node)
292 {
293         struct rb_node **p = &root->rb_node;
294         struct rb_node *parent = NULL;
295         struct tree_entry *entry;
296
297         while (*p) {
298                 parent = *p;
299                 entry = rb_entry(parent, struct tree_entry, rb_node);
300
301                 if (bytenr < entry->bytenr)
302                         p = &(*p)->rb_left;
303                 else if (bytenr > entry->bytenr)
304                         p = &(*p)->rb_right;
305                 else
306                         return parent;
307         }
308
309         rb_link_node(node, parent, p);
310         rb_insert_color(node, root);
311         return NULL;
312 }
313
314 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
315 {
316         struct rb_node *n = root->rb_node;
317         struct tree_entry *entry;
318
319         while (n) {
320                 entry = rb_entry(n, struct tree_entry, rb_node);
321
322                 if (bytenr < entry->bytenr)
323                         n = n->rb_left;
324                 else if (bytenr > entry->bytenr)
325                         n = n->rb_right;
326                 else
327                         return n;
328         }
329         return NULL;
330 }
331
332 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
333 {
334
335         struct btrfs_fs_info *fs_info = NULL;
336         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
337                                               rb_node);
338         if (bnode->root)
339                 fs_info = bnode->root->fs_info;
340         btrfs_panic(fs_info, errno,
341                     "Inconsistency in backref cache found at offset %llu",
342                     bytenr);
343 }
344
345 /*
346  * walk up backref nodes until reach node presents tree root
347  */
348 static struct backref_node *walk_up_backref(struct backref_node *node,
349                                             struct backref_edge *edges[],
350                                             int *index)
351 {
352         struct backref_edge *edge;
353         int idx = *index;
354
355         while (!list_empty(&node->upper)) {
356                 edge = list_entry(node->upper.next,
357                                   struct backref_edge, list[LOWER]);
358                 edges[idx++] = edge;
359                 node = edge->node[UPPER];
360         }
361         BUG_ON(node->detached);
362         *index = idx;
363         return node;
364 }
365
366 /*
367  * walk down backref nodes to find start of next reference path
368  */
369 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
370                                               int *index)
371 {
372         struct backref_edge *edge;
373         struct backref_node *lower;
374         int idx = *index;
375
376         while (idx > 0) {
377                 edge = edges[idx - 1];
378                 lower = edge->node[LOWER];
379                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
380                         idx--;
381                         continue;
382                 }
383                 edge = list_entry(edge->list[LOWER].next,
384                                   struct backref_edge, list[LOWER]);
385                 edges[idx - 1] = edge;
386                 *index = idx;
387                 return edge->node[UPPER];
388         }
389         *index = 0;
390         return NULL;
391 }
392
393 static void unlock_node_buffer(struct backref_node *node)
394 {
395         if (node->locked) {
396                 btrfs_tree_unlock(node->eb);
397                 node->locked = 0;
398         }
399 }
400
401 static void drop_node_buffer(struct backref_node *node)
402 {
403         if (node->eb) {
404                 unlock_node_buffer(node);
405                 free_extent_buffer(node->eb);
406                 node->eb = NULL;
407         }
408 }
409
410 static void drop_backref_node(struct backref_cache *tree,
411                               struct backref_node *node)
412 {
413         BUG_ON(!list_empty(&node->upper));
414
415         drop_node_buffer(node);
416         list_del(&node->list);
417         list_del(&node->lower);
418         if (!RB_EMPTY_NODE(&node->rb_node))
419                 rb_erase(&node->rb_node, &tree->rb_root);
420         free_backref_node(tree, node);
421 }
422
423 /*
424  * remove a backref node from the backref cache
425  */
426 static void remove_backref_node(struct backref_cache *cache,
427                                 struct backref_node *node)
428 {
429         struct backref_node *upper;
430         struct backref_edge *edge;
431
432         if (!node)
433                 return;
434
435         BUG_ON(!node->lowest && !node->detached);
436         while (!list_empty(&node->upper)) {
437                 edge = list_entry(node->upper.next, struct backref_edge,
438                                   list[LOWER]);
439                 upper = edge->node[UPPER];
440                 list_del(&edge->list[LOWER]);
441                 list_del(&edge->list[UPPER]);
442                 free_backref_edge(cache, edge);
443
444                 if (RB_EMPTY_NODE(&upper->rb_node)) {
445                         BUG_ON(!list_empty(&node->upper));
446                         drop_backref_node(cache, node);
447                         node = upper;
448                         node->lowest = 1;
449                         continue;
450                 }
451                 /*
452                  * add the node to leaf node list if no other
453                  * child block cached.
454                  */
455                 if (list_empty(&upper->lower)) {
456                         list_add_tail(&upper->lower, &cache->leaves);
457                         upper->lowest = 1;
458                 }
459         }
460
461         drop_backref_node(cache, node);
462 }
463
464 static void update_backref_node(struct backref_cache *cache,
465                                 struct backref_node *node, u64 bytenr)
466 {
467         struct rb_node *rb_node;
468         rb_erase(&node->rb_node, &cache->rb_root);
469         node->bytenr = bytenr;
470         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
471         if (rb_node)
472                 backref_tree_panic(rb_node, -EEXIST, bytenr);
473 }
474
475 /*
476  * update backref cache after a transaction commit
477  */
478 static int update_backref_cache(struct btrfs_trans_handle *trans,
479                                 struct backref_cache *cache)
480 {
481         struct backref_node *node;
482         int level = 0;
483
484         if (cache->last_trans == 0) {
485                 cache->last_trans = trans->transid;
486                 return 0;
487         }
488
489         if (cache->last_trans == trans->transid)
490                 return 0;
491
492         /*
493          * detached nodes are used to avoid unnecessary backref
494          * lookup. transaction commit changes the extent tree.
495          * so the detached nodes are no longer useful.
496          */
497         while (!list_empty(&cache->detached)) {
498                 node = list_entry(cache->detached.next,
499                                   struct backref_node, list);
500                 remove_backref_node(cache, node);
501         }
502
503         while (!list_empty(&cache->changed)) {
504                 node = list_entry(cache->changed.next,
505                                   struct backref_node, list);
506                 list_del_init(&node->list);
507                 BUG_ON(node->pending);
508                 update_backref_node(cache, node, node->new_bytenr);
509         }
510
511         /*
512          * some nodes can be left in the pending list if there were
513          * errors during processing the pending nodes.
514          */
515         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
516                 list_for_each_entry(node, &cache->pending[level], list) {
517                         BUG_ON(!node->pending);
518                         if (node->bytenr == node->new_bytenr)
519                                 continue;
520                         update_backref_node(cache, node, node->new_bytenr);
521                 }
522         }
523
524         cache->last_trans = 0;
525         return 1;
526 }
527
528
529 static int should_ignore_root(struct btrfs_root *root)
530 {
531         struct btrfs_root *reloc_root;
532
533         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
534                 return 0;
535
536         reloc_root = root->reloc_root;
537         if (!reloc_root)
538                 return 0;
539
540         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
541             root->fs_info->running_transaction->transid - 1)
542                 return 0;
543         /*
544          * if there is reloc tree and it was created in previous
545          * transaction backref lookup can find the reloc tree,
546          * so backref node for the fs tree root is useless for
547          * relocation.
548          */
549         return 1;
550 }
551 /*
552  * find reloc tree by address of tree root
553  */
554 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
555                                           u64 bytenr)
556 {
557         struct rb_node *rb_node;
558         struct mapping_node *node;
559         struct btrfs_root *root = NULL;
560
561         spin_lock(&rc->reloc_root_tree.lock);
562         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
563         if (rb_node) {
564                 node = rb_entry(rb_node, struct mapping_node, rb_node);
565                 root = (struct btrfs_root *)node->data;
566         }
567         spin_unlock(&rc->reloc_root_tree.lock);
568         return root;
569 }
570
571 static int is_cowonly_root(u64 root_objectid)
572 {
573         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
574             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
575             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
576             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
577             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
578             root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
579             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
580             root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
581             root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
582                 return 1;
583         return 0;
584 }
585
586 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
587                                         u64 root_objectid)
588 {
589         struct btrfs_key key;
590
591         key.objectid = root_objectid;
592         key.type = BTRFS_ROOT_ITEM_KEY;
593         if (is_cowonly_root(root_objectid))
594                 key.offset = 0;
595         else
596                 key.offset = (u64)-1;
597
598         return btrfs_get_fs_root(fs_info, &key, false);
599 }
600
601 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
602 static noinline_for_stack
603 struct btrfs_root *find_tree_root(struct reloc_control *rc,
604                                   struct extent_buffer *leaf,
605                                   struct btrfs_extent_ref_v0 *ref0)
606 {
607         struct btrfs_root *root;
608         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
609         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
610
611         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
612
613         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
614         BUG_ON(IS_ERR(root));
615
616         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
617             generation != btrfs_root_generation(&root->root_item))
618                 return NULL;
619
620         return root;
621 }
622 #endif
623
624 static noinline_for_stack
625 int find_inline_backref(struct extent_buffer *leaf, int slot,
626                         unsigned long *ptr, unsigned long *end)
627 {
628         struct btrfs_key key;
629         struct btrfs_extent_item *ei;
630         struct btrfs_tree_block_info *bi;
631         u32 item_size;
632
633         btrfs_item_key_to_cpu(leaf, &key, slot);
634
635         item_size = btrfs_item_size_nr(leaf, slot);
636 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
637         if (item_size < sizeof(*ei)) {
638                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
639                 return 1;
640         }
641 #endif
642         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
643         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
644                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
645
646         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
647             item_size <= sizeof(*ei) + sizeof(*bi)) {
648                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
649                 return 1;
650         }
651         if (key.type == BTRFS_METADATA_ITEM_KEY &&
652             item_size <= sizeof(*ei)) {
653                 WARN_ON(item_size < sizeof(*ei));
654                 return 1;
655         }
656
657         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
658                 bi = (struct btrfs_tree_block_info *)(ei + 1);
659                 *ptr = (unsigned long)(bi + 1);
660         } else {
661                 *ptr = (unsigned long)(ei + 1);
662         }
663         *end = (unsigned long)ei + item_size;
664         return 0;
665 }
666
667 /*
668  * build backref tree for a given tree block. root of the backref tree
669  * corresponds the tree block, leaves of the backref tree correspond
670  * roots of b-trees that reference the tree block.
671  *
672  * the basic idea of this function is check backrefs of a given block
673  * to find upper level blocks that reference the block, and then check
674  * backrefs of these upper level blocks recursively. the recursion stop
675  * when tree root is reached or backrefs for the block is cached.
676  *
677  * NOTE: if we find backrefs for a block are cached, we know backrefs
678  * for all upper level blocks that directly/indirectly reference the
679  * block are also cached.
680  */
681 static noinline_for_stack
682 struct backref_node *build_backref_tree(struct reloc_control *rc,
683                                         struct btrfs_key *node_key,
684                                         int level, u64 bytenr)
685 {
686         struct backref_cache *cache = &rc->backref_cache;
687         struct btrfs_path *path1;
688         struct btrfs_path *path2;
689         struct extent_buffer *eb;
690         struct btrfs_root *root;
691         struct backref_node *cur;
692         struct backref_node *upper;
693         struct backref_node *lower;
694         struct backref_node *node = NULL;
695         struct backref_node *exist = NULL;
696         struct backref_edge *edge;
697         struct rb_node *rb_node;
698         struct btrfs_key key;
699         unsigned long end;
700         unsigned long ptr;
701         LIST_HEAD(list);
702         LIST_HEAD(useless);
703         int cowonly;
704         int ret;
705         int err = 0;
706         bool need_check = true;
707
708         path1 = btrfs_alloc_path();
709         path2 = btrfs_alloc_path();
710         if (!path1 || !path2) {
711                 err = -ENOMEM;
712                 goto out;
713         }
714         path1->reada = READA_FORWARD;
715         path2->reada = READA_FORWARD;
716
717         node = alloc_backref_node(cache);
718         if (!node) {
719                 err = -ENOMEM;
720                 goto out;
721         }
722
723         node->bytenr = bytenr;
724         node->level = level;
725         node->lowest = 1;
726         cur = node;
727 again:
728         end = 0;
729         ptr = 0;
730         key.objectid = cur->bytenr;
731         key.type = BTRFS_METADATA_ITEM_KEY;
732         key.offset = (u64)-1;
733
734         path1->search_commit_root = 1;
735         path1->skip_locking = 1;
736         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
737                                 0, 0);
738         if (ret < 0) {
739                 err = ret;
740                 goto out;
741         }
742         ASSERT(ret);
743         ASSERT(path1->slots[0]);
744
745         path1->slots[0]--;
746
747         WARN_ON(cur->checked);
748         if (!list_empty(&cur->upper)) {
749                 /*
750                  * the backref was added previously when processing
751                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
752                  */
753                 ASSERT(list_is_singular(&cur->upper));
754                 edge = list_entry(cur->upper.next, struct backref_edge,
755                                   list[LOWER]);
756                 ASSERT(list_empty(&edge->list[UPPER]));
757                 exist = edge->node[UPPER];
758                 /*
759                  * add the upper level block to pending list if we need
760                  * check its backrefs
761                  */
762                 if (!exist->checked)
763                         list_add_tail(&edge->list[UPPER], &list);
764         } else {
765                 exist = NULL;
766         }
767
768         while (1) {
769                 cond_resched();
770                 eb = path1->nodes[0];
771
772                 if (ptr >= end) {
773                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
774                                 ret = btrfs_next_leaf(rc->extent_root, path1);
775                                 if (ret < 0) {
776                                         err = ret;
777                                         goto out;
778                                 }
779                                 if (ret > 0)
780                                         break;
781                                 eb = path1->nodes[0];
782                         }
783
784                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
785                         if (key.objectid != cur->bytenr) {
786                                 WARN_ON(exist);
787                                 break;
788                         }
789
790                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
791                             key.type == BTRFS_METADATA_ITEM_KEY) {
792                                 ret = find_inline_backref(eb, path1->slots[0],
793                                                           &ptr, &end);
794                                 if (ret)
795                                         goto next;
796                         }
797                 }
798
799                 if (ptr < end) {
800                         /* update key for inline back ref */
801                         struct btrfs_extent_inline_ref *iref;
802                         iref = (struct btrfs_extent_inline_ref *)ptr;
803                         key.type = btrfs_extent_inline_ref_type(eb, iref);
804                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
805                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
806                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
807                 }
808
809                 if (exist &&
810                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
811                       exist->owner == key.offset) ||
812                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
813                       exist->bytenr == key.offset))) {
814                         exist = NULL;
815                         goto next;
816                 }
817
818 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
819                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
820                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
821                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
822                                 struct btrfs_extent_ref_v0 *ref0;
823                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
824                                                 struct btrfs_extent_ref_v0);
825                                 if (key.objectid == key.offset) {
826                                         root = find_tree_root(rc, eb, ref0);
827                                         if (root && !should_ignore_root(root))
828                                                 cur->root = root;
829                                         else
830                                                 list_add(&cur->list, &useless);
831                                         break;
832                                 }
833                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
834                                                                       ref0)))
835                                         cur->cowonly = 1;
836                         }
837 #else
838                 ASSERT(key.type != BTRFS_EXTENT_REF_V0_KEY);
839                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
840 #endif
841                         if (key.objectid == key.offset) {
842                                 /*
843                                  * only root blocks of reloc trees use
844                                  * backref of this type.
845                                  */
846                                 root = find_reloc_root(rc, cur->bytenr);
847                                 ASSERT(root);
848                                 cur->root = root;
849                                 break;
850                         }
851
852                         edge = alloc_backref_edge(cache);
853                         if (!edge) {
854                                 err = -ENOMEM;
855                                 goto out;
856                         }
857                         rb_node = tree_search(&cache->rb_root, key.offset);
858                         if (!rb_node) {
859                                 upper = alloc_backref_node(cache);
860                                 if (!upper) {
861                                         free_backref_edge(cache, edge);
862                                         err = -ENOMEM;
863                                         goto out;
864                                 }
865                                 upper->bytenr = key.offset;
866                                 upper->level = cur->level + 1;
867                                 /*
868                                  *  backrefs for the upper level block isn't
869                                  *  cached, add the block to pending list
870                                  */
871                                 list_add_tail(&edge->list[UPPER], &list);
872                         } else {
873                                 upper = rb_entry(rb_node, struct backref_node,
874                                                  rb_node);
875                                 ASSERT(upper->checked);
876                                 INIT_LIST_HEAD(&edge->list[UPPER]);
877                         }
878                         list_add_tail(&edge->list[LOWER], &cur->upper);
879                         edge->node[LOWER] = cur;
880                         edge->node[UPPER] = upper;
881
882                         goto next;
883                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
884                         goto next;
885                 }
886
887                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
888                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
889                 if (IS_ERR(root)) {
890                         err = PTR_ERR(root);
891                         goto out;
892                 }
893
894                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
895                         cur->cowonly = 1;
896
897                 if (btrfs_root_level(&root->root_item) == cur->level) {
898                         /* tree root */
899                         ASSERT(btrfs_root_bytenr(&root->root_item) ==
900                                cur->bytenr);
901                         if (should_ignore_root(root))
902                                 list_add(&cur->list, &useless);
903                         else
904                                 cur->root = root;
905                         break;
906                 }
907
908                 level = cur->level + 1;
909
910                 /*
911                  * searching the tree to find upper level blocks
912                  * reference the block.
913                  */
914                 path2->search_commit_root = 1;
915                 path2->skip_locking = 1;
916                 path2->lowest_level = level;
917                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
918                 path2->lowest_level = 0;
919                 if (ret < 0) {
920                         err = ret;
921                         goto out;
922                 }
923                 if (ret > 0 && path2->slots[level] > 0)
924                         path2->slots[level]--;
925
926                 eb = path2->nodes[level];
927                 if (btrfs_node_blockptr(eb, path2->slots[level]) !=
928                     cur->bytenr) {
929                         btrfs_err(root->fs_info,
930         "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
931                                   cur->bytenr, level - 1, root->objectid,
932                                   node_key->objectid, node_key->type,
933                                   node_key->offset);
934                         err = -ENOENT;
935                         goto out;
936                 }
937                 lower = cur;
938                 need_check = true;
939                 for (; level < BTRFS_MAX_LEVEL; level++) {
940                         if (!path2->nodes[level]) {
941                                 ASSERT(btrfs_root_bytenr(&root->root_item) ==
942                                        lower->bytenr);
943                                 if (should_ignore_root(root))
944                                         list_add(&lower->list, &useless);
945                                 else
946                                         lower->root = root;
947                                 break;
948                         }
949
950                         edge = alloc_backref_edge(cache);
951                         if (!edge) {
952                                 err = -ENOMEM;
953                                 goto out;
954                         }
955
956                         eb = path2->nodes[level];
957                         rb_node = tree_search(&cache->rb_root, eb->start);
958                         if (!rb_node) {
959                                 upper = alloc_backref_node(cache);
960                                 if (!upper) {
961                                         free_backref_edge(cache, edge);
962                                         err = -ENOMEM;
963                                         goto out;
964                                 }
965                                 upper->bytenr = eb->start;
966                                 upper->owner = btrfs_header_owner(eb);
967                                 upper->level = lower->level + 1;
968                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
969                                               &root->state))
970                                         upper->cowonly = 1;
971
972                                 /*
973                                  * if we know the block isn't shared
974                                  * we can void checking its backrefs.
975                                  */
976                                 if (btrfs_block_can_be_shared(root, eb))
977                                         upper->checked = 0;
978                                 else
979                                         upper->checked = 1;
980
981                                 /*
982                                  * add the block to pending list if we
983                                  * need check its backrefs, we only do this once
984                                  * while walking up a tree as we will catch
985                                  * anything else later on.
986                                  */
987                                 if (!upper->checked && need_check) {
988                                         need_check = false;
989                                         list_add_tail(&edge->list[UPPER],
990                                                       &list);
991                                 } else {
992                                         if (upper->checked)
993                                                 need_check = true;
994                                         INIT_LIST_HEAD(&edge->list[UPPER]);
995                                 }
996                         } else {
997                                 upper = rb_entry(rb_node, struct backref_node,
998                                                  rb_node);
999                                 ASSERT(upper->checked);
1000                                 INIT_LIST_HEAD(&edge->list[UPPER]);
1001                                 if (!upper->owner)
1002                                         upper->owner = btrfs_header_owner(eb);
1003                         }
1004                         list_add_tail(&edge->list[LOWER], &lower->upper);
1005                         edge->node[LOWER] = lower;
1006                         edge->node[UPPER] = upper;
1007
1008                         if (rb_node)
1009                                 break;
1010                         lower = upper;
1011                         upper = NULL;
1012                 }
1013                 btrfs_release_path(path2);
1014 next:
1015                 if (ptr < end) {
1016                         ptr += btrfs_extent_inline_ref_size(key.type);
1017                         if (ptr >= end) {
1018                                 WARN_ON(ptr > end);
1019                                 ptr = 0;
1020                                 end = 0;
1021                         }
1022                 }
1023                 if (ptr >= end)
1024                         path1->slots[0]++;
1025         }
1026         btrfs_release_path(path1);
1027
1028         cur->checked = 1;
1029         WARN_ON(exist);
1030
1031         /* the pending list isn't empty, take the first block to process */
1032         if (!list_empty(&list)) {
1033                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1034                 list_del_init(&edge->list[UPPER]);
1035                 cur = edge->node[UPPER];
1036                 goto again;
1037         }
1038
1039         /*
1040          * everything goes well, connect backref nodes and insert backref nodes
1041          * into the cache.
1042          */
1043         ASSERT(node->checked);
1044         cowonly = node->cowonly;
1045         if (!cowonly) {
1046                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1047                                       &node->rb_node);
1048                 if (rb_node)
1049                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1050                 list_add_tail(&node->lower, &cache->leaves);
1051         }
1052
1053         list_for_each_entry(edge, &node->upper, list[LOWER])
1054                 list_add_tail(&edge->list[UPPER], &list);
1055
1056         while (!list_empty(&list)) {
1057                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1058                 list_del_init(&edge->list[UPPER]);
1059                 upper = edge->node[UPPER];
1060                 if (upper->detached) {
1061                         list_del(&edge->list[LOWER]);
1062                         lower = edge->node[LOWER];
1063                         free_backref_edge(cache, edge);
1064                         if (list_empty(&lower->upper))
1065                                 list_add(&lower->list, &useless);
1066                         continue;
1067                 }
1068
1069                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1070                         if (upper->lowest) {
1071                                 list_del_init(&upper->lower);
1072                                 upper->lowest = 0;
1073                         }
1074
1075                         list_add_tail(&edge->list[UPPER], &upper->lower);
1076                         continue;
1077                 }
1078
1079                 if (!upper->checked) {
1080                         /*
1081                          * Still want to blow up for developers since this is a
1082                          * logic bug.
1083                          */
1084                         ASSERT(0);
1085                         err = -EINVAL;
1086                         goto out;
1087                 }
1088                 if (cowonly != upper->cowonly) {
1089                         ASSERT(0);
1090                         err = -EINVAL;
1091                         goto out;
1092                 }
1093
1094                 if (!cowonly) {
1095                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1096                                               &upper->rb_node);
1097                         if (rb_node)
1098                                 backref_tree_panic(rb_node, -EEXIST,
1099                                                    upper->bytenr);
1100                 }
1101
1102                 list_add_tail(&edge->list[UPPER], &upper->lower);
1103
1104                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1105                         list_add_tail(&edge->list[UPPER], &list);
1106         }
1107         /*
1108          * process useless backref nodes. backref nodes for tree leaves
1109          * are deleted from the cache. backref nodes for upper level
1110          * tree blocks are left in the cache to avoid unnecessary backref
1111          * lookup.
1112          */
1113         while (!list_empty(&useless)) {
1114                 upper = list_entry(useless.next, struct backref_node, list);
1115                 list_del_init(&upper->list);
1116                 ASSERT(list_empty(&upper->upper));
1117                 if (upper == node)
1118                         node = NULL;
1119                 if (upper->lowest) {
1120                         list_del_init(&upper->lower);
1121                         upper->lowest = 0;
1122                 }
1123                 while (!list_empty(&upper->lower)) {
1124                         edge = list_entry(upper->lower.next,
1125                                           struct backref_edge, list[UPPER]);
1126                         list_del(&edge->list[UPPER]);
1127                         list_del(&edge->list[LOWER]);
1128                         lower = edge->node[LOWER];
1129                         free_backref_edge(cache, edge);
1130
1131                         if (list_empty(&lower->upper))
1132                                 list_add(&lower->list, &useless);
1133                 }
1134                 __mark_block_processed(rc, upper);
1135                 if (upper->level > 0) {
1136                         list_add(&upper->list, &cache->detached);
1137                         upper->detached = 1;
1138                 } else {
1139                         rb_erase(&upper->rb_node, &cache->rb_root);
1140                         free_backref_node(cache, upper);
1141                 }
1142         }
1143 out:
1144         btrfs_free_path(path1);
1145         btrfs_free_path(path2);
1146         if (err) {
1147                 while (!list_empty(&useless)) {
1148                         lower = list_entry(useless.next,
1149                                            struct backref_node, list);
1150                         list_del_init(&lower->list);
1151                 }
1152                 while (!list_empty(&list)) {
1153                         edge = list_first_entry(&list, struct backref_edge,
1154                                                 list[UPPER]);
1155                         list_del(&edge->list[UPPER]);
1156                         list_del(&edge->list[LOWER]);
1157                         lower = edge->node[LOWER];
1158                         upper = edge->node[UPPER];
1159                         free_backref_edge(cache, edge);
1160
1161                         /*
1162                          * Lower is no longer linked to any upper backref nodes
1163                          * and isn't in the cache, we can free it ourselves.
1164                          */
1165                         if (list_empty(&lower->upper) &&
1166                             RB_EMPTY_NODE(&lower->rb_node))
1167                                 list_add(&lower->list, &useless);
1168
1169                         if (!RB_EMPTY_NODE(&upper->rb_node))
1170                                 continue;
1171
1172                         /* Add this guy's upper edges to the list to process */
1173                         list_for_each_entry(edge, &upper->upper, list[LOWER])
1174                                 list_add_tail(&edge->list[UPPER], &list);
1175                         if (list_empty(&upper->upper))
1176                                 list_add(&upper->list, &useless);
1177                 }
1178
1179                 while (!list_empty(&useless)) {
1180                         lower = list_entry(useless.next,
1181                                            struct backref_node, list);
1182                         list_del_init(&lower->list);
1183                         if (lower == node)
1184                                 node = NULL;
1185                         free_backref_node(cache, lower);
1186                 }
1187
1188                 free_backref_node(cache, node);
1189                 return ERR_PTR(err);
1190         }
1191         ASSERT(!node || !node->detached);
1192         return node;
1193 }
1194
1195 /*
1196  * helper to add backref node for the newly created snapshot.
1197  * the backref node is created by cloning backref node that
1198  * corresponds to root of source tree
1199  */
1200 static int clone_backref_node(struct btrfs_trans_handle *trans,
1201                               struct reloc_control *rc,
1202                               struct btrfs_root *src,
1203                               struct btrfs_root *dest)
1204 {
1205         struct btrfs_root *reloc_root = src->reloc_root;
1206         struct backref_cache *cache = &rc->backref_cache;
1207         struct backref_node *node = NULL;
1208         struct backref_node *new_node;
1209         struct backref_edge *edge;
1210         struct backref_edge *new_edge;
1211         struct rb_node *rb_node;
1212
1213         if (cache->last_trans > 0)
1214                 update_backref_cache(trans, cache);
1215
1216         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1217         if (rb_node) {
1218                 node = rb_entry(rb_node, struct backref_node, rb_node);
1219                 if (node->detached)
1220                         node = NULL;
1221                 else
1222                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1223         }
1224
1225         if (!node) {
1226                 rb_node = tree_search(&cache->rb_root,
1227                                       reloc_root->commit_root->start);
1228                 if (rb_node) {
1229                         node = rb_entry(rb_node, struct backref_node,
1230                                         rb_node);
1231                         BUG_ON(node->detached);
1232                 }
1233         }
1234
1235         if (!node)
1236                 return 0;
1237
1238         new_node = alloc_backref_node(cache);
1239         if (!new_node)
1240                 return -ENOMEM;
1241
1242         new_node->bytenr = dest->node->start;
1243         new_node->level = node->level;
1244         new_node->lowest = node->lowest;
1245         new_node->checked = 1;
1246         new_node->root = dest;
1247
1248         if (!node->lowest) {
1249                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1250                         new_edge = alloc_backref_edge(cache);
1251                         if (!new_edge)
1252                                 goto fail;
1253
1254                         new_edge->node[UPPER] = new_node;
1255                         new_edge->node[LOWER] = edge->node[LOWER];
1256                         list_add_tail(&new_edge->list[UPPER],
1257                                       &new_node->lower);
1258                 }
1259         } else {
1260                 list_add_tail(&new_node->lower, &cache->leaves);
1261         }
1262
1263         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1264                               &new_node->rb_node);
1265         if (rb_node)
1266                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1267
1268         if (!new_node->lowest) {
1269                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1270                         list_add_tail(&new_edge->list[LOWER],
1271                                       &new_edge->node[LOWER]->upper);
1272                 }
1273         }
1274         return 0;
1275 fail:
1276         while (!list_empty(&new_node->lower)) {
1277                 new_edge = list_entry(new_node->lower.next,
1278                                       struct backref_edge, list[UPPER]);
1279                 list_del(&new_edge->list[UPPER]);
1280                 free_backref_edge(cache, new_edge);
1281         }
1282         free_backref_node(cache, new_node);
1283         return -ENOMEM;
1284 }
1285
1286 /*
1287  * helper to add 'address of tree root -> reloc tree' mapping
1288  */
1289 static int __must_check __add_reloc_root(struct btrfs_root *root)
1290 {
1291         struct btrfs_fs_info *fs_info = root->fs_info;
1292         struct rb_node *rb_node;
1293         struct mapping_node *node;
1294         struct reloc_control *rc = fs_info->reloc_ctl;
1295
1296         node = kmalloc(sizeof(*node), GFP_NOFS);
1297         if (!node)
1298                 return -ENOMEM;
1299
1300         node->bytenr = root->node->start;
1301         node->data = root;
1302
1303         spin_lock(&rc->reloc_root_tree.lock);
1304         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1305                               node->bytenr, &node->rb_node);
1306         spin_unlock(&rc->reloc_root_tree.lock);
1307         if (rb_node) {
1308                 btrfs_panic(fs_info, -EEXIST,
1309                             "Duplicate root found for start=%llu while inserting into relocation tree",
1310                             node->bytenr);
1311                 kfree(node);
1312                 return -EEXIST;
1313         }
1314
1315         list_add_tail(&root->root_list, &rc->reloc_roots);
1316         return 0;
1317 }
1318
1319 /*
1320  * helper to delete the 'address of tree root -> reloc tree'
1321  * mapping
1322  */
1323 static void __del_reloc_root(struct btrfs_root *root)
1324 {
1325         struct btrfs_fs_info *fs_info = root->fs_info;
1326         struct rb_node *rb_node;
1327         struct mapping_node *node = NULL;
1328         struct reloc_control *rc = fs_info->reloc_ctl;
1329
1330         spin_lock(&rc->reloc_root_tree.lock);
1331         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1332                               root->node->start);
1333         if (rb_node) {
1334                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1335                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1336         }
1337         spin_unlock(&rc->reloc_root_tree.lock);
1338
1339         if (!node)
1340                 return;
1341         BUG_ON((struct btrfs_root *)node->data != root);
1342
1343         spin_lock(&fs_info->trans_lock);
1344         list_del_init(&root->root_list);
1345         spin_unlock(&fs_info->trans_lock);
1346         kfree(node);
1347 }
1348
1349 /*
1350  * helper to update the 'address of tree root -> reloc tree'
1351  * mapping
1352  */
1353 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1354 {
1355         struct btrfs_fs_info *fs_info = root->fs_info;
1356         struct rb_node *rb_node;
1357         struct mapping_node *node = NULL;
1358         struct reloc_control *rc = fs_info->reloc_ctl;
1359
1360         spin_lock(&rc->reloc_root_tree.lock);
1361         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1362                               root->node->start);
1363         if (rb_node) {
1364                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1365                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1366         }
1367         spin_unlock(&rc->reloc_root_tree.lock);
1368
1369         if (!node)
1370                 return 0;
1371         BUG_ON((struct btrfs_root *)node->data != root);
1372
1373         spin_lock(&rc->reloc_root_tree.lock);
1374         node->bytenr = new_bytenr;
1375         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1376                               node->bytenr, &node->rb_node);
1377         spin_unlock(&rc->reloc_root_tree.lock);
1378         if (rb_node)
1379                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1380         return 0;
1381 }
1382
1383 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1384                                         struct btrfs_root *root, u64 objectid)
1385 {
1386         struct btrfs_fs_info *fs_info = root->fs_info;
1387         struct btrfs_root *reloc_root;
1388         struct extent_buffer *eb;
1389         struct btrfs_root_item *root_item;
1390         struct btrfs_key root_key;
1391         int ret;
1392
1393         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1394         BUG_ON(!root_item);
1395
1396         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1397         root_key.type = BTRFS_ROOT_ITEM_KEY;
1398         root_key.offset = objectid;
1399
1400         if (root->root_key.objectid == objectid) {
1401                 u64 commit_root_gen;
1402
1403                 /* called by btrfs_init_reloc_root */
1404                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1405                                       BTRFS_TREE_RELOC_OBJECTID);
1406                 BUG_ON(ret);
1407                 /*
1408                  * Set the last_snapshot field to the generation of the commit
1409                  * root - like this ctree.c:btrfs_block_can_be_shared() behaves
1410                  * correctly (returns true) when the relocation root is created
1411                  * either inside the critical section of a transaction commit
1412                  * (through transaction.c:qgroup_account_snapshot()) and when
1413                  * it's created before the transaction commit is started.
1414                  */
1415                 commit_root_gen = btrfs_header_generation(root->commit_root);
1416                 btrfs_set_root_last_snapshot(&root->root_item, commit_root_gen);
1417         } else {
1418                 /*
1419                  * called by btrfs_reloc_post_snapshot_hook.
1420                  * the source tree is a reloc tree, all tree blocks
1421                  * modified after it was created have RELOC flag
1422                  * set in their headers. so it's OK to not update
1423                  * the 'last_snapshot'.
1424                  */
1425                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1426                                       BTRFS_TREE_RELOC_OBJECTID);
1427                 BUG_ON(ret);
1428         }
1429
1430         memcpy(root_item, &root->root_item, sizeof(*root_item));
1431         btrfs_set_root_bytenr(root_item, eb->start);
1432         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1433         btrfs_set_root_generation(root_item, trans->transid);
1434
1435         if (root->root_key.objectid == objectid) {
1436                 btrfs_set_root_refs(root_item, 0);
1437                 memset(&root_item->drop_progress, 0,
1438                        sizeof(struct btrfs_disk_key));
1439                 root_item->drop_level = 0;
1440         }
1441
1442         btrfs_tree_unlock(eb);
1443         free_extent_buffer(eb);
1444
1445         ret = btrfs_insert_root(trans, fs_info->tree_root,
1446                                 &root_key, root_item);
1447         BUG_ON(ret);
1448         kfree(root_item);
1449
1450         reloc_root = btrfs_read_fs_root(fs_info->tree_root, &root_key);
1451         BUG_ON(IS_ERR(reloc_root));
1452         reloc_root->last_trans = trans->transid;
1453         return reloc_root;
1454 }
1455
1456 /*
1457  * create reloc tree for a given fs tree. reloc tree is just a
1458  * snapshot of the fs tree with special root objectid.
1459  */
1460 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1461                           struct btrfs_root *root)
1462 {
1463         struct btrfs_fs_info *fs_info = root->fs_info;
1464         struct btrfs_root *reloc_root;
1465         struct reloc_control *rc = fs_info->reloc_ctl;
1466         struct btrfs_block_rsv *rsv;
1467         int clear_rsv = 0;
1468         int ret;
1469
1470         if (root->reloc_root) {
1471                 reloc_root = root->reloc_root;
1472                 reloc_root->last_trans = trans->transid;
1473                 return 0;
1474         }
1475
1476         if (!rc || !rc->create_reloc_tree ||
1477             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1478                 return 0;
1479
1480         if (!trans->reloc_reserved) {
1481                 rsv = trans->block_rsv;
1482                 trans->block_rsv = rc->block_rsv;
1483                 clear_rsv = 1;
1484         }
1485         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1486         if (clear_rsv)
1487                 trans->block_rsv = rsv;
1488
1489         ret = __add_reloc_root(reloc_root);
1490         BUG_ON(ret < 0);
1491         root->reloc_root = reloc_root;
1492         return 0;
1493 }
1494
1495 /*
1496  * update root item of reloc tree
1497  */
1498 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1499                             struct btrfs_root *root)
1500 {
1501         struct btrfs_fs_info *fs_info = root->fs_info;
1502         struct btrfs_root *reloc_root;
1503         struct btrfs_root_item *root_item;
1504         int ret;
1505
1506         if (!root->reloc_root)
1507                 goto out;
1508
1509         reloc_root = root->reloc_root;
1510         root_item = &reloc_root->root_item;
1511
1512         if (fs_info->reloc_ctl->merge_reloc_tree &&
1513             btrfs_root_refs(root_item) == 0) {
1514                 root->reloc_root = NULL;
1515                 __del_reloc_root(reloc_root);
1516         }
1517
1518         if (reloc_root->commit_root != reloc_root->node) {
1519                 btrfs_set_root_node(root_item, reloc_root->node);
1520                 free_extent_buffer(reloc_root->commit_root);
1521                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1522         }
1523
1524         ret = btrfs_update_root(trans, fs_info->tree_root,
1525                                 &reloc_root->root_key, root_item);
1526         BUG_ON(ret);
1527
1528 out:
1529         return 0;
1530 }
1531
1532 /*
1533  * helper to find first cached inode with inode number >= objectid
1534  * in a subvolume
1535  */
1536 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1537 {
1538         struct rb_node *node;
1539         struct rb_node *prev;
1540         struct btrfs_inode *entry;
1541         struct inode *inode;
1542
1543         spin_lock(&root->inode_lock);
1544 again:
1545         node = root->inode_tree.rb_node;
1546         prev = NULL;
1547         while (node) {
1548                 prev = node;
1549                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1550
1551                 if (objectid < btrfs_ino(entry))
1552                         node = node->rb_left;
1553                 else if (objectid > btrfs_ino(entry))
1554                         node = node->rb_right;
1555                 else
1556                         break;
1557         }
1558         if (!node) {
1559                 while (prev) {
1560                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1561                         if (objectid <= btrfs_ino(entry)) {
1562                                 node = prev;
1563                                 break;
1564                         }
1565                         prev = rb_next(prev);
1566                 }
1567         }
1568         while (node) {
1569                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1570                 inode = igrab(&entry->vfs_inode);
1571                 if (inode) {
1572                         spin_unlock(&root->inode_lock);
1573                         return inode;
1574                 }
1575
1576                 objectid = btrfs_ino(entry) + 1;
1577                 if (cond_resched_lock(&root->inode_lock))
1578                         goto again;
1579
1580                 node = rb_next(node);
1581         }
1582         spin_unlock(&root->inode_lock);
1583         return NULL;
1584 }
1585
1586 static int in_block_group(u64 bytenr,
1587                           struct btrfs_block_group_cache *block_group)
1588 {
1589         if (bytenr >= block_group->key.objectid &&
1590             bytenr < block_group->key.objectid + block_group->key.offset)
1591                 return 1;
1592         return 0;
1593 }
1594
1595 /*
1596  * get new location of data
1597  */
1598 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1599                             u64 bytenr, u64 num_bytes)
1600 {
1601         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1602         struct btrfs_path *path;
1603         struct btrfs_file_extent_item *fi;
1604         struct extent_buffer *leaf;
1605         int ret;
1606
1607         path = btrfs_alloc_path();
1608         if (!path)
1609                 return -ENOMEM;
1610
1611         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1612         ret = btrfs_lookup_file_extent(NULL, root, path,
1613                         btrfs_ino(BTRFS_I(reloc_inode)), bytenr, 0);
1614         if (ret < 0)
1615                 goto out;
1616         if (ret > 0) {
1617                 ret = -ENOENT;
1618                 goto out;
1619         }
1620
1621         leaf = path->nodes[0];
1622         fi = btrfs_item_ptr(leaf, path->slots[0],
1623                             struct btrfs_file_extent_item);
1624
1625         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1626                btrfs_file_extent_compression(leaf, fi) ||
1627                btrfs_file_extent_encryption(leaf, fi) ||
1628                btrfs_file_extent_other_encoding(leaf, fi));
1629
1630         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1631                 ret = -EINVAL;
1632                 goto out;
1633         }
1634
1635         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1636         ret = 0;
1637 out:
1638         btrfs_free_path(path);
1639         return ret;
1640 }
1641
1642 /*
1643  * update file extent items in the tree leaf to point to
1644  * the new locations.
1645  */
1646 static noinline_for_stack
1647 int replace_file_extents(struct btrfs_trans_handle *trans,
1648                          struct reloc_control *rc,
1649                          struct btrfs_root *root,
1650                          struct extent_buffer *leaf)
1651 {
1652         struct btrfs_fs_info *fs_info = root->fs_info;
1653         struct btrfs_key key;
1654         struct btrfs_file_extent_item *fi;
1655         struct inode *inode = NULL;
1656         u64 parent;
1657         u64 bytenr;
1658         u64 new_bytenr = 0;
1659         u64 num_bytes;
1660         u64 end;
1661         u32 nritems;
1662         u32 i;
1663         int ret = 0;
1664         int first = 1;
1665         int dirty = 0;
1666
1667         if (rc->stage != UPDATE_DATA_PTRS)
1668                 return 0;
1669
1670         /* reloc trees always use full backref */
1671         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1672                 parent = leaf->start;
1673         else
1674                 parent = 0;
1675
1676         nritems = btrfs_header_nritems(leaf);
1677         for (i = 0; i < nritems; i++) {
1678                 cond_resched();
1679                 btrfs_item_key_to_cpu(leaf, &key, i);
1680                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1681                         continue;
1682                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1683                 if (btrfs_file_extent_type(leaf, fi) ==
1684                     BTRFS_FILE_EXTENT_INLINE)
1685                         continue;
1686                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1687                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1688                 if (bytenr == 0)
1689                         continue;
1690                 if (!in_block_group(bytenr, rc->block_group))
1691                         continue;
1692
1693                 /*
1694                  * if we are modifying block in fs tree, wait for readpage
1695                  * to complete and drop the extent cache
1696                  */
1697                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1698                         if (first) {
1699                                 inode = find_next_inode(root, key.objectid);
1700                                 first = 0;
1701                         } else if (inode && btrfs_ino(BTRFS_I(inode)) < key.objectid) {
1702                                 btrfs_add_delayed_iput(inode);
1703                                 inode = find_next_inode(root, key.objectid);
1704                         }
1705                         if (inode && btrfs_ino(BTRFS_I(inode)) == key.objectid) {
1706                                 end = key.offset +
1707                                       btrfs_file_extent_num_bytes(leaf, fi);
1708                                 WARN_ON(!IS_ALIGNED(key.offset,
1709                                                     fs_info->sectorsize));
1710                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
1711                                 end--;
1712                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1713                                                       key.offset, end);
1714                                 if (!ret)
1715                                         continue;
1716
1717                                 btrfs_drop_extent_cache(BTRFS_I(inode),
1718                                                 key.offset,     end, 1);
1719                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1720                                               key.offset, end);
1721                         }
1722                 }
1723
1724                 ret = get_new_location(rc->data_inode, &new_bytenr,
1725                                        bytenr, num_bytes);
1726                 if (ret) {
1727                         /*
1728                          * Don't have to abort since we've not changed anything
1729                          * in the file extent yet.
1730                          */
1731                         break;
1732                 }
1733
1734                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1735                 dirty = 1;
1736
1737                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1738                 ret = btrfs_inc_extent_ref(trans, fs_info, new_bytenr,
1739                                            num_bytes, parent,
1740                                            btrfs_header_owner(leaf),
1741                                            key.objectid, key.offset);
1742                 if (ret) {
1743                         btrfs_abort_transaction(trans, ret);
1744                         break;
1745                 }
1746
1747                 ret = btrfs_free_extent(trans, fs_info, bytenr, num_bytes,
1748                                         parent, btrfs_header_owner(leaf),
1749                                         key.objectid, key.offset);
1750                 if (ret) {
1751                         btrfs_abort_transaction(trans, ret);
1752                         break;
1753                 }
1754         }
1755         if (dirty)
1756                 btrfs_mark_buffer_dirty(leaf);
1757         if (inode)
1758                 btrfs_add_delayed_iput(inode);
1759         return ret;
1760 }
1761
1762 static noinline_for_stack
1763 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1764                      struct btrfs_path *path, int level)
1765 {
1766         struct btrfs_disk_key key1;
1767         struct btrfs_disk_key key2;
1768         btrfs_node_key(eb, &key1, slot);
1769         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1770         return memcmp(&key1, &key2, sizeof(key1));
1771 }
1772
1773 /*
1774  * try to replace tree blocks in fs tree with the new blocks
1775  * in reloc tree. tree blocks haven't been modified since the
1776  * reloc tree was create can be replaced.
1777  *
1778  * if a block was replaced, level of the block + 1 is returned.
1779  * if no block got replaced, 0 is returned. if there are other
1780  * errors, a negative error number is returned.
1781  */
1782 static noinline_for_stack
1783 int replace_path(struct btrfs_trans_handle *trans,
1784                  struct btrfs_root *dest, struct btrfs_root *src,
1785                  struct btrfs_path *path, struct btrfs_key *next_key,
1786                  int lowest_level, int max_level)
1787 {
1788         struct btrfs_fs_info *fs_info = dest->fs_info;
1789         struct extent_buffer *eb;
1790         struct extent_buffer *parent;
1791         struct btrfs_key key;
1792         u64 old_bytenr;
1793         u64 new_bytenr;
1794         u64 old_ptr_gen;
1795         u64 new_ptr_gen;
1796         u64 last_snapshot;
1797         u32 blocksize;
1798         int cow = 0;
1799         int level;
1800         int ret;
1801         int slot;
1802
1803         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1804         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1805
1806         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1807 again:
1808         slot = path->slots[lowest_level];
1809         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1810
1811         eb = btrfs_lock_root_node(dest);
1812         btrfs_set_lock_blocking(eb);
1813         level = btrfs_header_level(eb);
1814
1815         if (level < lowest_level) {
1816                 btrfs_tree_unlock(eb);
1817                 free_extent_buffer(eb);
1818                 return 0;
1819         }
1820
1821         if (cow) {
1822                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1823                 BUG_ON(ret);
1824         }
1825         btrfs_set_lock_blocking(eb);
1826
1827         if (next_key) {
1828                 next_key->objectid = (u64)-1;
1829                 next_key->type = (u8)-1;
1830                 next_key->offset = (u64)-1;
1831         }
1832
1833         parent = eb;
1834         while (1) {
1835                 level = btrfs_header_level(parent);
1836                 BUG_ON(level < lowest_level);
1837
1838                 ret = btrfs_bin_search(parent, &key, level, &slot);
1839                 if (ret && slot > 0)
1840                         slot--;
1841
1842                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1843                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1844
1845                 old_bytenr = btrfs_node_blockptr(parent, slot);
1846                 blocksize = fs_info->nodesize;
1847                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1848
1849                 if (level <= max_level) {
1850                         eb = path->nodes[level];
1851                         new_bytenr = btrfs_node_blockptr(eb,
1852                                                         path->slots[level]);
1853                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1854                                                         path->slots[level]);
1855                 } else {
1856                         new_bytenr = 0;
1857                         new_ptr_gen = 0;
1858                 }
1859
1860                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1861                         ret = level;
1862                         break;
1863                 }
1864
1865                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1866                     memcmp_node_keys(parent, slot, path, level)) {
1867                         if (level <= lowest_level) {
1868                                 ret = 0;
1869                                 break;
1870                         }
1871
1872                         eb = read_tree_block(fs_info, old_bytenr, old_ptr_gen);
1873                         if (IS_ERR(eb)) {
1874                                 ret = PTR_ERR(eb);
1875                                 break;
1876                         } else if (!extent_buffer_uptodate(eb)) {
1877                                 ret = -EIO;
1878                                 free_extent_buffer(eb);
1879                                 break;
1880                         }
1881                         btrfs_tree_lock(eb);
1882                         if (cow) {
1883                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1884                                                       slot, &eb);
1885                                 BUG_ON(ret);
1886                         }
1887                         btrfs_set_lock_blocking(eb);
1888
1889                         btrfs_tree_unlock(parent);
1890                         free_extent_buffer(parent);
1891
1892                         parent = eb;
1893                         continue;
1894                 }
1895
1896                 if (!cow) {
1897                         btrfs_tree_unlock(parent);
1898                         free_extent_buffer(parent);
1899                         cow = 1;
1900                         goto again;
1901                 }
1902
1903                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1904                                       path->slots[level]);
1905                 btrfs_release_path(path);
1906
1907                 path->lowest_level = level;
1908                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1909                 path->lowest_level = 0;
1910                 BUG_ON(ret);
1911
1912                 /*
1913                  * Info qgroup to trace both subtrees.
1914                  *
1915                  * We must trace both trees.
1916                  * 1) Tree reloc subtree
1917                  *    If not traced, we will leak data numbers
1918                  * 2) Fs subtree
1919                  *    If not traced, we will double count old data
1920                  *    and tree block numbers, if current trans doesn't free
1921                  *    data reloc tree inode.
1922                  */
1923                 ret = btrfs_qgroup_trace_subtree(trans, src, parent,
1924                                 btrfs_header_generation(parent),
1925                                 btrfs_header_level(parent));
1926                 if (ret < 0)
1927                         break;
1928                 ret = btrfs_qgroup_trace_subtree(trans, dest,
1929                                 path->nodes[level],
1930                                 btrfs_header_generation(path->nodes[level]),
1931                                 btrfs_header_level(path->nodes[level]));
1932                 if (ret < 0)
1933                         break;
1934
1935                 /*
1936                  * swap blocks in fs tree and reloc tree.
1937                  */
1938                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1939                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1940                 btrfs_mark_buffer_dirty(parent);
1941
1942                 btrfs_set_node_blockptr(path->nodes[level],
1943                                         path->slots[level], old_bytenr);
1944                 btrfs_set_node_ptr_generation(path->nodes[level],
1945                                               path->slots[level], old_ptr_gen);
1946                 btrfs_mark_buffer_dirty(path->nodes[level]);
1947
1948                 ret = btrfs_inc_extent_ref(trans, fs_info, old_bytenr,
1949                                         blocksize, path->nodes[level]->start,
1950                                         src->root_key.objectid, level - 1, 0);
1951                 BUG_ON(ret);
1952                 ret = btrfs_inc_extent_ref(trans, fs_info, new_bytenr,
1953                                         blocksize, 0, dest->root_key.objectid,
1954                                         level - 1, 0);
1955                 BUG_ON(ret);
1956
1957                 ret = btrfs_free_extent(trans, fs_info, new_bytenr, blocksize,
1958                                         path->nodes[level]->start,
1959                                         src->root_key.objectid, level - 1, 0);
1960                 BUG_ON(ret);
1961
1962                 ret = btrfs_free_extent(trans, fs_info, old_bytenr, blocksize,
1963                                         0, dest->root_key.objectid, level - 1,
1964                                         0);
1965                 BUG_ON(ret);
1966
1967                 btrfs_unlock_up_safe(path, 0);
1968
1969                 ret = level;
1970                 break;
1971         }
1972         btrfs_tree_unlock(parent);
1973         free_extent_buffer(parent);
1974         return ret;
1975 }
1976
1977 /*
1978  * helper to find next relocated block in reloc tree
1979  */
1980 static noinline_for_stack
1981 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1982                        int *level)
1983 {
1984         struct extent_buffer *eb;
1985         int i;
1986         u64 last_snapshot;
1987         u32 nritems;
1988
1989         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1990
1991         for (i = 0; i < *level; i++) {
1992                 free_extent_buffer(path->nodes[i]);
1993                 path->nodes[i] = NULL;
1994         }
1995
1996         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1997                 eb = path->nodes[i];
1998                 nritems = btrfs_header_nritems(eb);
1999                 while (path->slots[i] + 1 < nritems) {
2000                         path->slots[i]++;
2001                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
2002                             last_snapshot)
2003                                 continue;
2004
2005                         *level = i;
2006                         return 0;
2007                 }
2008                 free_extent_buffer(path->nodes[i]);
2009                 path->nodes[i] = NULL;
2010         }
2011         return 1;
2012 }
2013
2014 /*
2015  * walk down reloc tree to find relocated block of lowest level
2016  */
2017 static noinline_for_stack
2018 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
2019                          int *level)
2020 {
2021         struct btrfs_fs_info *fs_info = root->fs_info;
2022         struct extent_buffer *eb = NULL;
2023         int i;
2024         u64 bytenr;
2025         u64 ptr_gen = 0;
2026         u64 last_snapshot;
2027         u32 nritems;
2028
2029         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
2030
2031         for (i = *level; i > 0; i--) {
2032                 eb = path->nodes[i];
2033                 nritems = btrfs_header_nritems(eb);
2034                 while (path->slots[i] < nritems) {
2035                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
2036                         if (ptr_gen > last_snapshot)
2037                                 break;
2038                         path->slots[i]++;
2039                 }
2040                 if (path->slots[i] >= nritems) {
2041                         if (i == *level)
2042                                 break;
2043                         *level = i + 1;
2044                         return 0;
2045                 }
2046                 if (i == 1) {
2047                         *level = i;
2048                         return 0;
2049                 }
2050
2051                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2052                 eb = read_tree_block(fs_info, bytenr, ptr_gen);
2053                 if (IS_ERR(eb)) {
2054                         return PTR_ERR(eb);
2055                 } else if (!extent_buffer_uptodate(eb)) {
2056                         free_extent_buffer(eb);
2057                         return -EIO;
2058                 }
2059                 BUG_ON(btrfs_header_level(eb) != i - 1);
2060                 path->nodes[i - 1] = eb;
2061                 path->slots[i - 1] = 0;
2062         }
2063         return 1;
2064 }
2065
2066 /*
2067  * invalidate extent cache for file extents whose key in range of
2068  * [min_key, max_key)
2069  */
2070 static int invalidate_extent_cache(struct btrfs_root *root,
2071                                    struct btrfs_key *min_key,
2072                                    struct btrfs_key *max_key)
2073 {
2074         struct btrfs_fs_info *fs_info = root->fs_info;
2075         struct inode *inode = NULL;
2076         u64 objectid;
2077         u64 start, end;
2078         u64 ino;
2079
2080         objectid = min_key->objectid;
2081         while (1) {
2082                 cond_resched();
2083                 iput(inode);
2084
2085                 if (objectid > max_key->objectid)
2086                         break;
2087
2088                 inode = find_next_inode(root, objectid);
2089                 if (!inode)
2090                         break;
2091                 ino = btrfs_ino(BTRFS_I(inode));
2092
2093                 if (ino > max_key->objectid) {
2094                         iput(inode);
2095                         break;
2096                 }
2097
2098                 objectid = ino + 1;
2099                 if (!S_ISREG(inode->i_mode))
2100                         continue;
2101
2102                 if (unlikely(min_key->objectid == ino)) {
2103                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2104                                 continue;
2105                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2106                                 start = 0;
2107                         else {
2108                                 start = min_key->offset;
2109                                 WARN_ON(!IS_ALIGNED(start, fs_info->sectorsize));
2110                         }
2111                 } else {
2112                         start = 0;
2113                 }
2114
2115                 if (unlikely(max_key->objectid == ino)) {
2116                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2117                                 continue;
2118                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2119                                 end = (u64)-1;
2120                         } else {
2121                                 if (max_key->offset == 0)
2122                                         continue;
2123                                 end = max_key->offset;
2124                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
2125                                 end--;
2126                         }
2127                 } else {
2128                         end = (u64)-1;
2129                 }
2130
2131                 /* the lock_extent waits for readpage to complete */
2132                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2133                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 1);
2134                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2135         }
2136         return 0;
2137 }
2138
2139 static int find_next_key(struct btrfs_path *path, int level,
2140                          struct btrfs_key *key)
2141
2142 {
2143         while (level < BTRFS_MAX_LEVEL) {
2144                 if (!path->nodes[level])
2145                         break;
2146                 if (path->slots[level] + 1 <
2147                     btrfs_header_nritems(path->nodes[level])) {
2148                         btrfs_node_key_to_cpu(path->nodes[level], key,
2149                                               path->slots[level] + 1);
2150                         return 0;
2151                 }
2152                 level++;
2153         }
2154         return 1;
2155 }
2156
2157 /*
2158  * merge the relocated tree blocks in reloc tree with corresponding
2159  * fs tree.
2160  */
2161 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2162                                                struct btrfs_root *root)
2163 {
2164         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2165         LIST_HEAD(inode_list);
2166         struct btrfs_key key;
2167         struct btrfs_key next_key;
2168         struct btrfs_trans_handle *trans = NULL;
2169         struct btrfs_root *reloc_root;
2170         struct btrfs_root_item *root_item;
2171         struct btrfs_path *path;
2172         struct extent_buffer *leaf;
2173         int level;
2174         int max_level;
2175         int replaced = 0;
2176         int ret;
2177         int err = 0;
2178         u32 min_reserved;
2179
2180         path = btrfs_alloc_path();
2181         if (!path)
2182                 return -ENOMEM;
2183         path->reada = READA_FORWARD;
2184
2185         reloc_root = root->reloc_root;
2186         root_item = &reloc_root->root_item;
2187
2188         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2189                 level = btrfs_root_level(root_item);
2190                 extent_buffer_get(reloc_root->node);
2191                 path->nodes[level] = reloc_root->node;
2192                 path->slots[level] = 0;
2193         } else {
2194                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2195
2196                 level = root_item->drop_level;
2197                 BUG_ON(level == 0);
2198                 path->lowest_level = level;
2199                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2200                 path->lowest_level = 0;
2201                 if (ret < 0) {
2202                         btrfs_free_path(path);
2203                         return ret;
2204                 }
2205
2206                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2207                                       path->slots[level]);
2208                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2209
2210                 btrfs_unlock_up_safe(path, 0);
2211         }
2212
2213         min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2214         memset(&next_key, 0, sizeof(next_key));
2215
2216         while (1) {
2217                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2218                                              BTRFS_RESERVE_FLUSH_ALL);
2219                 if (ret) {
2220                         err = ret;
2221                         goto out;
2222                 }
2223                 trans = btrfs_start_transaction(root, 0);
2224                 if (IS_ERR(trans)) {
2225                         err = PTR_ERR(trans);
2226                         trans = NULL;
2227                         goto out;
2228                 }
2229                 trans->block_rsv = rc->block_rsv;
2230
2231                 replaced = 0;
2232                 max_level = level;
2233
2234                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2235                 if (ret < 0) {
2236                         err = ret;
2237                         goto out;
2238                 }
2239                 if (ret > 0)
2240                         break;
2241
2242                 if (!find_next_key(path, level, &key) &&
2243                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2244                         ret = 0;
2245                 } else {
2246                         ret = replace_path(trans, root, reloc_root, path,
2247                                            &next_key, level, max_level);
2248                 }
2249                 if (ret < 0) {
2250                         err = ret;
2251                         goto out;
2252                 }
2253
2254                 if (ret > 0) {
2255                         level = ret;
2256                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2257                                               path->slots[level]);
2258                         replaced = 1;
2259                 }
2260
2261                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2262                 if (ret > 0)
2263                         break;
2264
2265                 BUG_ON(level == 0);
2266                 /*
2267                  * save the merging progress in the drop_progress.
2268                  * this is OK since root refs == 1 in this case.
2269                  */
2270                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2271                                path->slots[level]);
2272                 root_item->drop_level = level;
2273
2274                 btrfs_end_transaction_throttle(trans);
2275                 trans = NULL;
2276
2277                 btrfs_btree_balance_dirty(fs_info);
2278
2279                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2280                         invalidate_extent_cache(root, &key, &next_key);
2281         }
2282
2283         /*
2284          * handle the case only one block in the fs tree need to be
2285          * relocated and the block is tree root.
2286          */
2287         leaf = btrfs_lock_root_node(root);
2288         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2289         btrfs_tree_unlock(leaf);
2290         free_extent_buffer(leaf);
2291         if (ret < 0)
2292                 err = ret;
2293 out:
2294         btrfs_free_path(path);
2295
2296         if (err == 0) {
2297                 memset(&root_item->drop_progress, 0,
2298                        sizeof(root_item->drop_progress));
2299                 root_item->drop_level = 0;
2300                 btrfs_set_root_refs(root_item, 0);
2301                 btrfs_update_reloc_root(trans, root);
2302         }
2303
2304         if (trans)
2305                 btrfs_end_transaction_throttle(trans);
2306
2307         btrfs_btree_balance_dirty(fs_info);
2308
2309         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2310                 invalidate_extent_cache(root, &key, &next_key);
2311
2312         return err;
2313 }
2314
2315 static noinline_for_stack
2316 int prepare_to_merge(struct reloc_control *rc, int err)
2317 {
2318         struct btrfs_root *root = rc->extent_root;
2319         struct btrfs_fs_info *fs_info = root->fs_info;
2320         struct btrfs_root *reloc_root;
2321         struct btrfs_trans_handle *trans;
2322         LIST_HEAD(reloc_roots);
2323         u64 num_bytes = 0;
2324         int ret;
2325
2326         mutex_lock(&fs_info->reloc_mutex);
2327         rc->merging_rsv_size += fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2328         rc->merging_rsv_size += rc->nodes_relocated * 2;
2329         mutex_unlock(&fs_info->reloc_mutex);
2330
2331 again:
2332         if (!err) {
2333                 num_bytes = rc->merging_rsv_size;
2334                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2335                                           BTRFS_RESERVE_FLUSH_ALL);
2336                 if (ret)
2337                         err = ret;
2338         }
2339
2340         trans = btrfs_join_transaction(rc->extent_root);
2341         if (IS_ERR(trans)) {
2342                 if (!err)
2343                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2344                                                 num_bytes);
2345                 return PTR_ERR(trans);
2346         }
2347
2348         if (!err) {
2349                 if (num_bytes != rc->merging_rsv_size) {
2350                         btrfs_end_transaction(trans);
2351                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2352                                                 num_bytes);
2353                         goto again;
2354                 }
2355         }
2356
2357         rc->merge_reloc_tree = 1;
2358
2359         while (!list_empty(&rc->reloc_roots)) {
2360                 reloc_root = list_entry(rc->reloc_roots.next,
2361                                         struct btrfs_root, root_list);
2362                 list_del_init(&reloc_root->root_list);
2363
2364                 root = read_fs_root(fs_info, reloc_root->root_key.offset);
2365                 BUG_ON(IS_ERR(root));
2366                 BUG_ON(root->reloc_root != reloc_root);
2367
2368                 /*
2369                  * set reference count to 1, so btrfs_recover_relocation
2370                  * knows it should resumes merging
2371                  */
2372                 if (!err)
2373                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2374                 btrfs_update_reloc_root(trans, root);
2375
2376                 list_add(&reloc_root->root_list, &reloc_roots);
2377         }
2378
2379         list_splice(&reloc_roots, &rc->reloc_roots);
2380
2381         if (!err)
2382                 btrfs_commit_transaction(trans);
2383         else
2384                 btrfs_end_transaction(trans);
2385         return err;
2386 }
2387
2388 static noinline_for_stack
2389 void free_reloc_roots(struct list_head *list)
2390 {
2391         struct btrfs_root *reloc_root;
2392
2393         while (!list_empty(list)) {
2394                 reloc_root = list_entry(list->next, struct btrfs_root,
2395                                         root_list);
2396                 free_extent_buffer(reloc_root->node);
2397                 free_extent_buffer(reloc_root->commit_root);
2398                 reloc_root->node = NULL;
2399                 reloc_root->commit_root = NULL;
2400                 __del_reloc_root(reloc_root);
2401         }
2402 }
2403
2404 static noinline_for_stack
2405 void merge_reloc_roots(struct reloc_control *rc)
2406 {
2407         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2408         struct btrfs_root *root;
2409         struct btrfs_root *reloc_root;
2410         LIST_HEAD(reloc_roots);
2411         int found = 0;
2412         int ret = 0;
2413 again:
2414         root = rc->extent_root;
2415
2416         /*
2417          * this serializes us with btrfs_record_root_in_transaction,
2418          * we have to make sure nobody is in the middle of
2419          * adding their roots to the list while we are
2420          * doing this splice
2421          */
2422         mutex_lock(&fs_info->reloc_mutex);
2423         list_splice_init(&rc->reloc_roots, &reloc_roots);
2424         mutex_unlock(&fs_info->reloc_mutex);
2425
2426         while (!list_empty(&reloc_roots)) {
2427                 found = 1;
2428                 reloc_root = list_entry(reloc_roots.next,
2429                                         struct btrfs_root, root_list);
2430
2431                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2432                         root = read_fs_root(fs_info,
2433                                             reloc_root->root_key.offset);
2434                         BUG_ON(IS_ERR(root));
2435                         BUG_ON(root->reloc_root != reloc_root);
2436
2437                         ret = merge_reloc_root(rc, root);
2438                         if (ret) {
2439                                 if (list_empty(&reloc_root->root_list))
2440                                         list_add_tail(&reloc_root->root_list,
2441                                                       &reloc_roots);
2442                                 goto out;
2443                         }
2444                 } else {
2445                         list_del_init(&reloc_root->root_list);
2446                 }
2447
2448                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2449                 if (ret < 0) {
2450                         if (list_empty(&reloc_root->root_list))
2451                                 list_add_tail(&reloc_root->root_list,
2452                                               &reloc_roots);
2453                         goto out;
2454                 }
2455         }
2456
2457         if (found) {
2458                 found = 0;
2459                 goto again;
2460         }
2461 out:
2462         if (ret) {
2463                 btrfs_handle_fs_error(fs_info, ret, NULL);
2464                 if (!list_empty(&reloc_roots))
2465                         free_reloc_roots(&reloc_roots);
2466
2467                 /* new reloc root may be added */
2468                 mutex_lock(&fs_info->reloc_mutex);
2469                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2470                 mutex_unlock(&fs_info->reloc_mutex);
2471                 if (!list_empty(&reloc_roots))
2472                         free_reloc_roots(&reloc_roots);
2473         }
2474
2475         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2476 }
2477
2478 static void free_block_list(struct rb_root *blocks)
2479 {
2480         struct tree_block *block;
2481         struct rb_node *rb_node;
2482         while ((rb_node = rb_first(blocks))) {
2483                 block = rb_entry(rb_node, struct tree_block, rb_node);
2484                 rb_erase(rb_node, blocks);
2485                 kfree(block);
2486         }
2487 }
2488
2489 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2490                                       struct btrfs_root *reloc_root)
2491 {
2492         struct btrfs_fs_info *fs_info = reloc_root->fs_info;
2493         struct btrfs_root *root;
2494
2495         if (reloc_root->last_trans == trans->transid)
2496                 return 0;
2497
2498         root = read_fs_root(fs_info, reloc_root->root_key.offset);
2499         BUG_ON(IS_ERR(root));
2500         BUG_ON(root->reloc_root != reloc_root);
2501
2502         return btrfs_record_root_in_trans(trans, root);
2503 }
2504
2505 static noinline_for_stack
2506 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2507                                      struct reloc_control *rc,
2508                                      struct backref_node *node,
2509                                      struct backref_edge *edges[])
2510 {
2511         struct backref_node *next;
2512         struct btrfs_root *root;
2513         int index = 0;
2514
2515         next = node;
2516         while (1) {
2517                 cond_resched();
2518                 next = walk_up_backref(next, edges, &index);
2519                 root = next->root;
2520                 BUG_ON(!root);
2521                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2522
2523                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2524                         record_reloc_root_in_trans(trans, root);
2525                         break;
2526                 }
2527
2528                 btrfs_record_root_in_trans(trans, root);
2529                 root = root->reloc_root;
2530
2531                 if (next->new_bytenr != root->node->start) {
2532                         BUG_ON(next->new_bytenr);
2533                         BUG_ON(!list_empty(&next->list));
2534                         next->new_bytenr = root->node->start;
2535                         next->root = root;
2536                         list_add_tail(&next->list,
2537                                       &rc->backref_cache.changed);
2538                         __mark_block_processed(rc, next);
2539                         break;
2540                 }
2541
2542                 WARN_ON(1);
2543                 root = NULL;
2544                 next = walk_down_backref(edges, &index);
2545                 if (!next || next->level <= node->level)
2546                         break;
2547         }
2548         if (!root)
2549                 return NULL;
2550
2551         next = node;
2552         /* setup backref node path for btrfs_reloc_cow_block */
2553         while (1) {
2554                 rc->backref_cache.path[next->level] = next;
2555                 if (--index < 0)
2556                         break;
2557                 next = edges[index]->node[UPPER];
2558         }
2559         return root;
2560 }
2561
2562 /*
2563  * select a tree root for relocation. return NULL if the block
2564  * is reference counted. we should use do_relocation() in this
2565  * case. return a tree root pointer if the block isn't reference
2566  * counted. return -ENOENT if the block is root of reloc tree.
2567  */
2568 static noinline_for_stack
2569 struct btrfs_root *select_one_root(struct backref_node *node)
2570 {
2571         struct backref_node *next;
2572         struct btrfs_root *root;
2573         struct btrfs_root *fs_root = NULL;
2574         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2575         int index = 0;
2576
2577         next = node;
2578         while (1) {
2579                 cond_resched();
2580                 next = walk_up_backref(next, edges, &index);
2581                 root = next->root;
2582                 BUG_ON(!root);
2583
2584                 /* no other choice for non-references counted tree */
2585                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2586                         return root;
2587
2588                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2589                         fs_root = root;
2590
2591                 if (next != node)
2592                         return NULL;
2593
2594                 next = walk_down_backref(edges, &index);
2595                 if (!next || next->level <= node->level)
2596                         break;
2597         }
2598
2599         if (!fs_root)
2600                 return ERR_PTR(-ENOENT);
2601         return fs_root;
2602 }
2603
2604 static noinline_for_stack
2605 u64 calcu_metadata_size(struct reloc_control *rc,
2606                         struct backref_node *node, int reserve)
2607 {
2608         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2609         struct backref_node *next = node;
2610         struct backref_edge *edge;
2611         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2612         u64 num_bytes = 0;
2613         int index = 0;
2614
2615         BUG_ON(reserve && node->processed);
2616
2617         while (next) {
2618                 cond_resched();
2619                 while (1) {
2620                         if (next->processed && (reserve || next != node))
2621                                 break;
2622
2623                         num_bytes += fs_info->nodesize;
2624
2625                         if (list_empty(&next->upper))
2626                                 break;
2627
2628                         edge = list_entry(next->upper.next,
2629                                           struct backref_edge, list[LOWER]);
2630                         edges[index++] = edge;
2631                         next = edge->node[UPPER];
2632                 }
2633                 next = walk_down_backref(edges, &index);
2634         }
2635         return num_bytes;
2636 }
2637
2638 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2639                                   struct reloc_control *rc,
2640                                   struct backref_node *node)
2641 {
2642         struct btrfs_root *root = rc->extent_root;
2643         struct btrfs_fs_info *fs_info = root->fs_info;
2644         u64 num_bytes;
2645         int ret;
2646         u64 tmp;
2647
2648         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2649
2650         trans->block_rsv = rc->block_rsv;
2651         rc->reserved_bytes += num_bytes;
2652
2653         /*
2654          * We are under a transaction here so we can only do limited flushing.
2655          * If we get an enospc just kick back -EAGAIN so we know to drop the
2656          * transaction and try to refill when we can flush all the things.
2657          */
2658         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2659                                 BTRFS_RESERVE_FLUSH_LIMIT);
2660         if (ret) {
2661                 tmp = fs_info->nodesize * RELOCATION_RESERVED_NODES;
2662                 while (tmp <= rc->reserved_bytes)
2663                         tmp <<= 1;
2664                 /*
2665                  * only one thread can access block_rsv at this point,
2666                  * so we don't need hold lock to protect block_rsv.
2667                  * we expand more reservation size here to allow enough
2668                  * space for relocation and we will return eailer in
2669                  * enospc case.
2670                  */
2671                 rc->block_rsv->size = tmp + fs_info->nodesize *
2672                                       RELOCATION_RESERVED_NODES;
2673                 return -EAGAIN;
2674         }
2675
2676         return 0;
2677 }
2678
2679 /*
2680  * relocate a block tree, and then update pointers in upper level
2681  * blocks that reference the block to point to the new location.
2682  *
2683  * if called by link_to_upper, the block has already been relocated.
2684  * in that case this function just updates pointers.
2685  */
2686 static int do_relocation(struct btrfs_trans_handle *trans,
2687                          struct reloc_control *rc,
2688                          struct backref_node *node,
2689                          struct btrfs_key *key,
2690                          struct btrfs_path *path, int lowest)
2691 {
2692         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2693         struct backref_node *upper;
2694         struct backref_edge *edge;
2695         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2696         struct btrfs_root *root;
2697         struct extent_buffer *eb;
2698         u32 blocksize;
2699         u64 bytenr;
2700         u64 generation;
2701         int slot;
2702         int ret;
2703         int err = 0;
2704
2705         BUG_ON(lowest && node->eb);
2706
2707         path->lowest_level = node->level + 1;
2708         rc->backref_cache.path[node->level] = node;
2709         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2710                 cond_resched();
2711
2712                 upper = edge->node[UPPER];
2713                 root = select_reloc_root(trans, rc, upper, edges);
2714                 BUG_ON(!root);
2715
2716                 if (upper->eb && !upper->locked) {
2717                         if (!lowest) {
2718                                 ret = btrfs_bin_search(upper->eb, key,
2719                                                        upper->level, &slot);
2720                                 BUG_ON(ret);
2721                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2722                                 if (node->eb->start == bytenr)
2723                                         goto next;
2724                         }
2725                         drop_node_buffer(upper);
2726                 }
2727
2728                 if (!upper->eb) {
2729                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2730                         if (ret) {
2731                                 if (ret < 0)
2732                                         err = ret;
2733                                 else
2734                                         err = -ENOENT;
2735
2736                                 btrfs_release_path(path);
2737                                 break;
2738                         }
2739
2740                         if (!upper->eb) {
2741                                 upper->eb = path->nodes[upper->level];
2742                                 path->nodes[upper->level] = NULL;
2743                         } else {
2744                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2745                         }
2746
2747                         upper->locked = 1;
2748                         path->locks[upper->level] = 0;
2749
2750                         slot = path->slots[upper->level];
2751                         btrfs_release_path(path);
2752                 } else {
2753                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2754                                                &slot);
2755                         BUG_ON(ret);
2756                 }
2757
2758                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2759                 if (lowest) {
2760                         if (bytenr != node->bytenr) {
2761                                 btrfs_err(root->fs_info,
2762                 "lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu",
2763                                           bytenr, node->bytenr, slot,
2764                                           upper->eb->start);
2765                                 err = -EIO;
2766                                 goto next;
2767                         }
2768                 } else {
2769                         if (node->eb->start == bytenr)
2770                                 goto next;
2771                 }
2772
2773                 blocksize = root->fs_info->nodesize;
2774                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2775                 eb = read_tree_block(fs_info, bytenr, generation);
2776                 if (IS_ERR(eb)) {
2777                         err = PTR_ERR(eb);
2778                         goto next;
2779                 } else if (!extent_buffer_uptodate(eb)) {
2780                         free_extent_buffer(eb);
2781                         err = -EIO;
2782                         goto next;
2783                 }
2784                 btrfs_tree_lock(eb);
2785                 btrfs_set_lock_blocking(eb);
2786
2787                 if (!node->eb) {
2788                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2789                                               slot, &eb);
2790                         btrfs_tree_unlock(eb);
2791                         free_extent_buffer(eb);
2792                         if (ret < 0) {
2793                                 err = ret;
2794                                 goto next;
2795                         }
2796                         BUG_ON(node->eb != eb);
2797                 } else {
2798                         btrfs_set_node_blockptr(upper->eb, slot,
2799                                                 node->eb->start);
2800                         btrfs_set_node_ptr_generation(upper->eb, slot,
2801                                                       trans->transid);
2802                         btrfs_mark_buffer_dirty(upper->eb);
2803
2804                         ret = btrfs_inc_extent_ref(trans, root->fs_info,
2805                                                 node->eb->start, blocksize,
2806                                                 upper->eb->start,
2807                                                 btrfs_header_owner(upper->eb),
2808                                                 node->level, 0);
2809                         BUG_ON(ret);
2810
2811                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2812                         BUG_ON(ret);
2813                 }
2814 next:
2815                 if (!upper->pending)
2816                         drop_node_buffer(upper);
2817                 else
2818                         unlock_node_buffer(upper);
2819                 if (err)
2820                         break;
2821         }
2822
2823         if (!err && node->pending) {
2824                 drop_node_buffer(node);
2825                 list_move_tail(&node->list, &rc->backref_cache.changed);
2826                 node->pending = 0;
2827         }
2828
2829         path->lowest_level = 0;
2830         BUG_ON(err == -ENOSPC);
2831         return err;
2832 }
2833
2834 static int link_to_upper(struct btrfs_trans_handle *trans,
2835                          struct reloc_control *rc,
2836                          struct backref_node *node,
2837                          struct btrfs_path *path)
2838 {
2839         struct btrfs_key key;
2840
2841         btrfs_node_key_to_cpu(node->eb, &key, 0);
2842         return do_relocation(trans, rc, node, &key, path, 0);
2843 }
2844
2845 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2846                                 struct reloc_control *rc,
2847                                 struct btrfs_path *path, int err)
2848 {
2849         LIST_HEAD(list);
2850         struct backref_cache *cache = &rc->backref_cache;
2851         struct backref_node *node;
2852         int level;
2853         int ret;
2854
2855         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2856                 while (!list_empty(&cache->pending[level])) {
2857                         node = list_entry(cache->pending[level].next,
2858                                           struct backref_node, list);
2859                         list_move_tail(&node->list, &list);
2860                         BUG_ON(!node->pending);
2861
2862                         if (!err) {
2863                                 ret = link_to_upper(trans, rc, node, path);
2864                                 if (ret < 0)
2865                                         err = ret;
2866                         }
2867                 }
2868                 list_splice_init(&list, &cache->pending[level]);
2869         }
2870         return err;
2871 }
2872
2873 static void mark_block_processed(struct reloc_control *rc,
2874                                  u64 bytenr, u32 blocksize)
2875 {
2876         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2877                         EXTENT_DIRTY);
2878 }
2879
2880 static void __mark_block_processed(struct reloc_control *rc,
2881                                    struct backref_node *node)
2882 {
2883         u32 blocksize;
2884         if (node->level == 0 ||
2885             in_block_group(node->bytenr, rc->block_group)) {
2886                 blocksize = rc->extent_root->fs_info->nodesize;
2887                 mark_block_processed(rc, node->bytenr, blocksize);
2888         }
2889         node->processed = 1;
2890 }
2891
2892 /*
2893  * mark a block and all blocks directly/indirectly reference the block
2894  * as processed.
2895  */
2896 static void update_processed_blocks(struct reloc_control *rc,
2897                                     struct backref_node *node)
2898 {
2899         struct backref_node *next = node;
2900         struct backref_edge *edge;
2901         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2902         int index = 0;
2903
2904         while (next) {
2905                 cond_resched();
2906                 while (1) {
2907                         if (next->processed)
2908                                 break;
2909
2910                         __mark_block_processed(rc, next);
2911
2912                         if (list_empty(&next->upper))
2913                                 break;
2914
2915                         edge = list_entry(next->upper.next,
2916                                           struct backref_edge, list[LOWER]);
2917                         edges[index++] = edge;
2918                         next = edge->node[UPPER];
2919                 }
2920                 next = walk_down_backref(edges, &index);
2921         }
2922 }
2923
2924 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2925 {
2926         u32 blocksize = rc->extent_root->fs_info->nodesize;
2927
2928         if (test_range_bit(&rc->processed_blocks, bytenr,
2929                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2930                 return 1;
2931         return 0;
2932 }
2933
2934 static int get_tree_block_key(struct btrfs_fs_info *fs_info,
2935                               struct tree_block *block)
2936 {
2937         struct extent_buffer *eb;
2938
2939         BUG_ON(block->key_ready);
2940         eb = read_tree_block(fs_info, block->bytenr, block->key.offset);
2941         if (IS_ERR(eb)) {
2942                 return PTR_ERR(eb);
2943         } else if (!extent_buffer_uptodate(eb)) {
2944                 free_extent_buffer(eb);
2945                 return -EIO;
2946         }
2947         WARN_ON(btrfs_header_level(eb) != block->level);
2948         if (block->level == 0)
2949                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2950         else
2951                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2952         free_extent_buffer(eb);
2953         block->key_ready = 1;
2954         return 0;
2955 }
2956
2957 /*
2958  * helper function to relocate a tree block
2959  */
2960 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2961                                 struct reloc_control *rc,
2962                                 struct backref_node *node,
2963                                 struct btrfs_key *key,
2964                                 struct btrfs_path *path)
2965 {
2966         struct btrfs_root *root;
2967         int ret = 0;
2968
2969         if (!node)
2970                 return 0;
2971
2972         BUG_ON(node->processed);
2973         root = select_one_root(node);
2974         if (root == ERR_PTR(-ENOENT)) {
2975                 update_processed_blocks(rc, node);
2976                 goto out;
2977         }
2978
2979         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2980                 ret = reserve_metadata_space(trans, rc, node);
2981                 if (ret)
2982                         goto out;
2983         }
2984
2985         if (root) {
2986                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2987                         BUG_ON(node->new_bytenr);
2988                         BUG_ON(!list_empty(&node->list));
2989                         btrfs_record_root_in_trans(trans, root);
2990                         root = root->reloc_root;
2991                         node->new_bytenr = root->node->start;
2992                         node->root = root;
2993                         list_add_tail(&node->list, &rc->backref_cache.changed);
2994                 } else {
2995                         path->lowest_level = node->level;
2996                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2997                         btrfs_release_path(path);
2998                         if (ret > 0)
2999                                 ret = 0;
3000                 }
3001                 if (!ret)
3002                         update_processed_blocks(rc, node);
3003         } else {
3004                 ret = do_relocation(trans, rc, node, key, path, 1);
3005         }
3006 out:
3007         if (ret || node->level == 0 || node->cowonly)
3008                 remove_backref_node(&rc->backref_cache, node);
3009         return ret;
3010 }
3011
3012 /*
3013  * relocate a list of blocks
3014  */
3015 static noinline_for_stack
3016 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
3017                          struct reloc_control *rc, struct rb_root *blocks)
3018 {
3019         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3020         struct backref_node *node;
3021         struct btrfs_path *path;
3022         struct tree_block *block;
3023         struct rb_node *rb_node;
3024         int ret;
3025         int err = 0;
3026
3027         path = btrfs_alloc_path();
3028         if (!path) {
3029                 err = -ENOMEM;
3030                 goto out_free_blocks;
3031         }
3032
3033         rb_node = rb_first(blocks);
3034         while (rb_node) {
3035                 block = rb_entry(rb_node, struct tree_block, rb_node);
3036                 if (!block->key_ready)
3037                         readahead_tree_block(fs_info, block->bytenr);
3038                 rb_node = rb_next(rb_node);
3039         }
3040
3041         rb_node = rb_first(blocks);
3042         while (rb_node) {
3043                 block = rb_entry(rb_node, struct tree_block, rb_node);
3044                 if (!block->key_ready) {
3045                         err = get_tree_block_key(fs_info, block);
3046                         if (err)
3047                                 goto out_free_path;
3048                 }
3049                 rb_node = rb_next(rb_node);
3050         }
3051
3052         rb_node = rb_first(blocks);
3053         while (rb_node) {
3054                 block = rb_entry(rb_node, struct tree_block, rb_node);
3055
3056                 node = build_backref_tree(rc, &block->key,
3057                                           block->level, block->bytenr);
3058                 if (IS_ERR(node)) {
3059                         err = PTR_ERR(node);
3060                         goto out;
3061                 }
3062
3063                 ret = relocate_tree_block(trans, rc, node, &block->key,
3064                                           path);
3065                 if (ret < 0) {
3066                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
3067                                 err = ret;
3068                         goto out;
3069                 }
3070                 rb_node = rb_next(rb_node);
3071         }
3072 out:
3073         err = finish_pending_nodes(trans, rc, path, err);
3074
3075 out_free_path:
3076         btrfs_free_path(path);
3077 out_free_blocks:
3078         free_block_list(blocks);
3079         return err;
3080 }
3081
3082 static noinline_for_stack
3083 int prealloc_file_extent_cluster(struct inode *inode,
3084                                  struct file_extent_cluster *cluster)
3085 {
3086         u64 alloc_hint = 0;
3087         u64 start;
3088         u64 end;
3089         u64 offset = BTRFS_I(inode)->index_cnt;
3090         u64 num_bytes;
3091         int nr = 0;
3092         int ret = 0;
3093         u64 prealloc_start = cluster->start - offset;
3094         u64 prealloc_end = cluster->end - offset;
3095         u64 cur_offset;
3096
3097         BUG_ON(cluster->start != cluster->boundary[0]);