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platform-drivers: x86: Convert pmic to new irq_chip functions
[zen-stable.git] / fs / btrfs / relocation.c
blob045c9c2b2d7ef7399f00370e4137d9da0b370836
1 /*
2 * Copyright (C) 2009 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/sched.h>
20 #include <linux/pagemap.h>
21 #include <linux/writeback.h>
22 #include <linux/blkdev.h>
23 #include <linux/rbtree.h>
24 #include <linux/slab.h>
25 #include "ctree.h"
26 #include "disk-io.h"
27 #include "transaction.h"
28 #include "volumes.h"
29 #include "locking.h"
30 #include "btrfs_inode.h"
31 #include "async-thread.h"
32 #include "free-space-cache.h"
33
34 /*
35 * backref_node, mapping_node and tree_block start with this
36 */
37 struct tree_entry {
38 struct rb_node rb_node;
39 u64 bytenr;
40 };
41
42 /*
43 * present a tree block in the backref cache
44 */
45 struct backref_node {
46 struct rb_node rb_node;
47 u64 bytenr;
48
49 u64 new_bytenr;
50 /* objectid of tree block owner, can be not uptodate */
51 u64 owner;
52 /* link to pending, changed or detached list */
53 struct list_head list;
54 /* list of upper level blocks reference this block */
55 struct list_head upper;
56 /* list of child blocks in the cache */
57 struct list_head lower;
58 /* NULL if this node is not tree root */
59 struct btrfs_root *root;
60 /* extent buffer got by COW the block */
61 struct extent_buffer *eb;
62 /* level of tree block */
63 unsigned int level:8;
64 /* is the block in non-reference counted tree */
65 unsigned int cowonly:1;
66 /* 1 if no child node in the cache */
67 unsigned int lowest:1;
68 /* is the extent buffer locked */
69 unsigned int locked:1;
70 /* has the block been processed */
71 unsigned int processed:1;
72 /* have backrefs of this block been checked */
73 unsigned int checked:1;
74 /*
75 * 1 if corresponding block has been cowed but some upper
76 * level block pointers may not point to the new location
77 */
78 unsigned int pending:1;
79 /*
80 * 1 if the backref node isn't connected to any other
81 * backref node.
82 */
83 unsigned int detached:1;
84 };
85
86 /*
87 * present a block pointer in the backref cache
88 */
89 struct backref_edge {
90 struct list_head list[2];
91 struct backref_node *node[2];
92 };
93
94 #define LOWER 0
95 #define UPPER 1
96
97 struct backref_cache {
98 /* red black tree of all backref nodes in the cache */
99 struct rb_root rb_root;
100 /* for passing backref nodes to btrfs_reloc_cow_block */
101 struct backref_node *path[BTRFS_MAX_LEVEL];
102 /*
103 * list of blocks that have been cowed but some block
104 * pointers in upper level blocks may not reflect the
105 * new location
106 */
107 struct list_head pending[BTRFS_MAX_LEVEL];
108 /* list of backref nodes with no child node */
109 struct list_head leaves;
110 /* list of blocks that have been cowed in current transaction */
111 struct list_head changed;
112 /* list of detached backref node. */
113 struct list_head detached;
114
115 u64 last_trans;
116
117 int nr_nodes;
118 int nr_edges;
119 };
120
121 /*
122 * map address of tree root to tree
123 */
124 struct mapping_node {
125 struct rb_node rb_node;
126 u64 bytenr;
127 void *data;
128 };
129
130 struct mapping_tree {
131 struct rb_root rb_root;
132 spinlock_t lock;
133 };
134
135 /*
136 * present a tree block to process
137 */
138 struct tree_block {
139 struct rb_node rb_node;
140 u64 bytenr;
141 struct btrfs_key key;
142 unsigned int level:8;
143 unsigned int key_ready:1;
144 };
145
146 #define MAX_EXTENTS 128
147
148 struct file_extent_cluster {
149 u64 start;
150 u64 end;
151 u64 boundary[MAX_EXTENTS];
152 unsigned int nr;
153 };
154
155 struct reloc_control {
156 /* block group to relocate */
157 struct btrfs_block_group_cache *block_group;
158 /* extent tree */
159 struct btrfs_root *extent_root;
160 /* inode for moving data */
161 struct inode *data_inode;
162
163 struct btrfs_block_rsv *block_rsv;
164
165 struct backref_cache backref_cache;
166
167 struct file_extent_cluster cluster;
168 /* tree blocks have been processed */
169 struct extent_io_tree processed_blocks;
170 /* map start of tree root to corresponding reloc tree */
171 struct mapping_tree reloc_root_tree;
172 /* list of reloc trees */
173 struct list_head reloc_roots;
174 /* size of metadata reservation for merging reloc trees */
175 u64 merging_rsv_size;
176 /* size of relocated tree nodes */
177 u64 nodes_relocated;
178
179 u64 search_start;
180 u64 extents_found;
181
182 unsigned int stage:8;
183 unsigned int create_reloc_tree:1;
184 unsigned int merge_reloc_tree:1;
185 unsigned int found_file_extent:1;
186 unsigned int commit_transaction:1;
187 };
188
189 /* stages of data relocation */
190 #define MOVE_DATA_EXTENTS 0
191 #define UPDATE_DATA_PTRS 1
192
193 static void remove_backref_node(struct backref_cache *cache,
194 struct backref_node *node);
195 static void __mark_block_processed(struct reloc_control *rc,
196 struct backref_node *node);
197
198 static void mapping_tree_init(struct mapping_tree *tree)
199 {
200 tree->rb_root = RB_ROOT;
201 spin_lock_init(&tree->lock);
202 }
203
204 static void backref_cache_init(struct backref_cache *cache)
205 {
206 int i;
207 cache->rb_root = RB_ROOT;
208 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
209 INIT_LIST_HEAD(&cache->pending[i]);
210 INIT_LIST_HEAD(&cache->changed);
211 INIT_LIST_HEAD(&cache->detached);
212 INIT_LIST_HEAD(&cache->leaves);
213 }
214
215 static void backref_cache_cleanup(struct backref_cache *cache)
216 {
217 struct backref_node *node;
218 int i;
219
220 while (!list_empty(&cache->detached)) {
221 node = list_entry(cache->detached.next,
222 struct backref_node, list);
223 remove_backref_node(cache, node);
224 }
225
226 while (!list_empty(&cache->leaves)) {
227 node = list_entry(cache->leaves.next,
228 struct backref_node, lower);
229 remove_backref_node(cache, node);
230 }
231
232 cache->last_trans = 0;
233
234 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
235 BUG_ON(!list_empty(&cache->pending[i]));
236 BUG_ON(!list_empty(&cache->changed));
237 BUG_ON(!list_empty(&cache->detached));
238 BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
239 BUG_ON(cache->nr_nodes);
240 BUG_ON(cache->nr_edges);
241 }
242
243 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
244 {
245 struct backref_node *node;
246
247 node = kzalloc(sizeof(*node), GFP_NOFS);
248 if (node) {
249 INIT_LIST_HEAD(&node->list);
250 INIT_LIST_HEAD(&node->upper);
251 INIT_LIST_HEAD(&node->lower);
252 RB_CLEAR_NODE(&node->rb_node);
253 cache->nr_nodes++;
254 }
255 return node;
256 }
257
258 static void free_backref_node(struct backref_cache *cache,
259 struct backref_node *node)
260 {
261 if (node) {
262 cache->nr_nodes--;
263 kfree(node);
264 }
265 }
266
267 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
268 {
269 struct backref_edge *edge;
270
271 edge = kzalloc(sizeof(*edge), GFP_NOFS);
272 if (edge)
273 cache->nr_edges++;
274 return edge;
275 }
276
277 static void free_backref_edge(struct backref_cache *cache,
278 struct backref_edge *edge)
279 {
280 if (edge) {
281 cache->nr_edges--;
282 kfree(edge);
283 }
284 }
285
286 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
287 struct rb_node *node)
288 {
289 struct rb_node **p = &root->rb_node;
290 struct rb_node *parent = NULL;
291 struct tree_entry *entry;
292
293 while (*p) {
294 parent = *p;
295 entry = rb_entry(parent, struct tree_entry, rb_node);
296
297 if (bytenr < entry->bytenr)
298 p = &(*p)->rb_left;
299 else if (bytenr > entry->bytenr)
300 p = &(*p)->rb_right;
301 else
302 return parent;
303 }
304
305 rb_link_node(node, parent, p);
306 rb_insert_color(node, root);
307 return NULL;
308 }
309
310 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
311 {
312 struct rb_node *n = root->rb_node;
313 struct tree_entry *entry;
314
315 while (n) {
316 entry = rb_entry(n, struct tree_entry, rb_node);
317
318 if (bytenr < entry->bytenr)
319 n = n->rb_left;
320 else if (bytenr > entry->bytenr)
321 n = n->rb_right;
322 else
323 return n;
324 }
325 return NULL;
326 }
327
328 /*
329 * walk up backref nodes until reach node presents tree root
330 */
331 static struct backref_node *walk_up_backref(struct backref_node *node,
332 struct backref_edge *edges[],
333 int *index)
334 {
335 struct backref_edge *edge;
336 int idx = *index;
337
338 while (!list_empty(&node->upper)) {
339 edge = list_entry(node->upper.next,
340 struct backref_edge, list[LOWER]);
341 edges[idx++] = edge;
342 node = edge->node[UPPER];
343 }
344 BUG_ON(node->detached);
345 *index = idx;
346 return node;
347 }
348
349 /*
350 * walk down backref nodes to find start of next reference path
351 */
352 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
353 int *index)
354 {
355 struct backref_edge *edge;
356 struct backref_node *lower;
357 int idx = *index;
358
359 while (idx > 0) {
360 edge = edges[idx - 1];
361 lower = edge->node[LOWER];
362 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
363 idx--;
364 continue;
365 }
366 edge = list_entry(edge->list[LOWER].next,
367 struct backref_edge, list[LOWER]);
368 edges[idx - 1] = edge;
369 *index = idx;
370 return edge->node[UPPER];
371 }
372 *index = 0;
373 return NULL;
374 }
375
376 static void unlock_node_buffer(struct backref_node *node)
377 {
378 if (node->locked) {
379 btrfs_tree_unlock(node->eb);
380 node->locked = 0;
381 }
382 }
383
384 static void drop_node_buffer(struct backref_node *node)
385 {
386 if (node->eb) {
387 unlock_node_buffer(node);
388 free_extent_buffer(node->eb);
389 node->eb = NULL;
390 }
391 }
392
393 static void drop_backref_node(struct backref_cache *tree,
394 struct backref_node *node)
395 {
396 BUG_ON(!list_empty(&node->upper));
397
398 drop_node_buffer(node);
399 list_del(&node->list);
400 list_del(&node->lower);
401 if (!RB_EMPTY_NODE(&node->rb_node))
402 rb_erase(&node->rb_node, &tree->rb_root);
403 free_backref_node(tree, node);
404 }
405
406 /*
407 * remove a backref node from the backref cache
408 */
409 static void remove_backref_node(struct backref_cache *cache,
410 struct backref_node *node)
411 {
412 struct backref_node *upper;
413 struct backref_edge *edge;
414
415 if (!node)
416 return;
417
418 BUG_ON(!node->lowest && !node->detached);
419 while (!list_empty(&node->upper)) {
420 edge = list_entry(node->upper.next, struct backref_edge,
421 list[LOWER]);
422 upper = edge->node[UPPER];
423 list_del(&edge->list[LOWER]);
424 list_del(&edge->list[UPPER]);
425 free_backref_edge(cache, edge);
426
427 if (RB_EMPTY_NODE(&upper->rb_node)) {
428 BUG_ON(!list_empty(&node->upper));
429 drop_backref_node(cache, node);
430 node = upper;
431 node->lowest = 1;
432 continue;
433 }
434 /*
435 * add the node to leaf node list if no other
436 * child block cached.
437 */
438 if (list_empty(&upper->lower)) {
439 list_add_tail(&upper->lower, &cache->leaves);
440 upper->lowest = 1;
441 }
442 }
443
444 drop_backref_node(cache, node);
445 }
446
447 static void update_backref_node(struct backref_cache *cache,
448 struct backref_node *node, u64 bytenr)
449 {
450 struct rb_node *rb_node;
451 rb_erase(&node->rb_node, &cache->rb_root);
452 node->bytenr = bytenr;
453 rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
454 BUG_ON(rb_node);
455 }
456
457 /*
458 * update backref cache after a transaction commit
459 */
460 static int update_backref_cache(struct btrfs_trans_handle *trans,
461 struct backref_cache *cache)
462 {
463 struct backref_node *node;
464 int level = 0;
465
466 if (cache->last_trans == 0) {
467 cache->last_trans = trans->transid;
468 return 0;
469 }
470
471 if (cache->last_trans == trans->transid)
472 return 0;
473
474 /*
475 * detached nodes are used to avoid unnecessary backref
476 * lookup. transaction commit changes the extent tree.
477 * so the detached nodes are no longer useful.
478 */
479 while (!list_empty(&cache->detached)) {
480 node = list_entry(cache->detached.next,
481 struct backref_node, list);
482 remove_backref_node(cache, node);
483 }
484
485 while (!list_empty(&cache->changed)) {
486 node = list_entry(cache->changed.next,
487 struct backref_node, list);
488 list_del_init(&node->list);
489 BUG_ON(node->pending);
490 update_backref_node(cache, node, node->new_bytenr);
491 }
492
493 /*
494 * some nodes can be left in the pending list if there were
495 * errors during processing the pending nodes.
496 */
497 for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
498 list_for_each_entry(node, &cache->pending[level], list) {
499 BUG_ON(!node->pending);
500 if (node->bytenr == node->new_bytenr)
501 continue;
502 update_backref_node(cache, node, node->new_bytenr);
503 }
504 }
505
506 cache->last_trans = 0;
507 return 1;
508 }
509
510 static int should_ignore_root(struct btrfs_root *root)
511 {
512 struct btrfs_root *reloc_root;
513
514 if (!root->ref_cows)
515 return 0;
516
517 reloc_root = root->reloc_root;
518 if (!reloc_root)
519 return 0;
520
521 if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
522 root->fs_info->running_transaction->transid - 1)
523 return 0;
524 /*
525 * if there is reloc tree and it was created in previous
526 * transaction backref lookup can find the reloc tree,
527 * so backref node for the fs tree root is useless for
528 * relocation.
529 */
530 return 1;
531 }
532
533 /*
534 * find reloc tree by address of tree root
535 */
536 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
537 u64 bytenr)
538 {
539 struct rb_node *rb_node;
540 struct mapping_node *node;
541 struct btrfs_root *root = NULL;
542
543 spin_lock(&rc->reloc_root_tree.lock);
544 rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
545 if (rb_node) {
546 node = rb_entry(rb_node, struct mapping_node, rb_node);
547 root = (struct btrfs_root *)node->data;
548 }
549 spin_unlock(&rc->reloc_root_tree.lock);
550 return root;
551 }
552
553 static int is_cowonly_root(u64 root_objectid)
554 {
555 if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
556 root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
557 root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
558 root_objectid == BTRFS_DEV_TREE_OBJECTID ||
559 root_objectid == BTRFS_TREE_LOG_OBJECTID ||
560 root_objectid == BTRFS_CSUM_TREE_OBJECTID)
561 return 1;
562 return 0;
563 }
564
565 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
566 u64 root_objectid)
567 {
568 struct btrfs_key key;
569
570 key.objectid = root_objectid;
571 key.type = BTRFS_ROOT_ITEM_KEY;
572 if (is_cowonly_root(root_objectid))
573 key.offset = 0;
574 else
575 key.offset = (u64)-1;
576
577 return btrfs_read_fs_root_no_name(fs_info, &key);
578 }
579
580 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
581 static noinline_for_stack
582 struct btrfs_root *find_tree_root(struct reloc_control *rc,
583 struct extent_buffer *leaf,
584 struct btrfs_extent_ref_v0 *ref0)
585 {
586 struct btrfs_root *root;
587 u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
588 u64 generation = btrfs_ref_generation_v0(leaf, ref0);
589
590 BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
591
592 root = read_fs_root(rc->extent_root->fs_info, root_objectid);
593 BUG_ON(IS_ERR(root));
594
595 if (root->ref_cows &&
596 generation != btrfs_root_generation(&root->root_item))
597 return NULL;
598
599 return root;
600 }
601 #endif
602
603 static noinline_for_stack
604 int find_inline_backref(struct extent_buffer *leaf, int slot,
605 unsigned long *ptr, unsigned long *end)
606 {
607 struct btrfs_extent_item *ei;
608 struct btrfs_tree_block_info *bi;
609 u32 item_size;
610
611 item_size = btrfs_item_size_nr(leaf, slot);
612 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
613 if (item_size < sizeof(*ei)) {
614 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
615 return 1;
616 }
617 #endif
618 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
619 WARN_ON(!(btrfs_extent_flags(leaf, ei) &
620 BTRFS_EXTENT_FLAG_TREE_BLOCK));
621
622 if (item_size <= sizeof(*ei) + sizeof(*bi)) {
623 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
624 return 1;
625 }
626
627 bi = (struct btrfs_tree_block_info *)(ei + 1);
628 *ptr = (unsigned long)(bi + 1);
629 *end = (unsigned long)ei + item_size;
630 return 0;
631 }
632
633 /*
634 * build backref tree for a given tree block. root of the backref tree
635 * corresponds the tree block, leaves of the backref tree correspond
636 * roots of b-trees that reference the tree block.
637 *
638 * the basic idea of this function is check backrefs of a given block
639 * to find upper level blocks that refernece the block, and then check
640 * bakcrefs of these upper level blocks recursively. the recursion stop
641 * when tree root is reached or backrefs for the block is cached.
642 *
643 * NOTE: if we find backrefs for a block are cached, we know backrefs
644 * for all upper level blocks that directly/indirectly reference the
645 * block are also cached.
646 */
647 static noinline_for_stack
648 struct backref_node *build_backref_tree(struct reloc_control *rc,
649 struct btrfs_key *node_key,
650 int level, u64 bytenr)
651 {
652 struct backref_cache *cache = &rc->backref_cache;
653 struct btrfs_path *path1;
654 struct btrfs_path *path2;
655 struct extent_buffer *eb;
656 struct btrfs_root *root;
657 struct backref_node *cur;
658 struct backref_node *upper;
659 struct backref_node *lower;
660 struct backref_node *node = NULL;
661 struct backref_node *exist = NULL;
662 struct backref_edge *edge;
663 struct rb_node *rb_node;
664 struct btrfs_key key;
665 unsigned long end;
666 unsigned long ptr;
667 LIST_HEAD(list);
668 LIST_HEAD(useless);
669 int cowonly;
670 int ret;
671 int err = 0;
672
673 path1 = btrfs_alloc_path();
674 path2 = btrfs_alloc_path();
675 if (!path1 || !path2) {
676 err = -ENOMEM;
677 goto out;
678 }
679
680 node = alloc_backref_node(cache);
681 if (!node) {
682 err = -ENOMEM;
683 goto out;
684 }
685
686 node->bytenr = bytenr;
687 node->level = level;
688 node->lowest = 1;
689 cur = node;
690 again:
691 end = 0;
692 ptr = 0;
693 key.objectid = cur->bytenr;
694 key.type = BTRFS_EXTENT_ITEM_KEY;
695 key.offset = (u64)-1;
696
697 path1->search_commit_root = 1;
698 path1->skip_locking = 1;
699 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
700 0, 0);
701 if (ret < 0) {
702 err = ret;
703 goto out;
704 }
705 BUG_ON(!ret || !path1->slots[0]);
706
707 path1->slots[0]--;
708
709 WARN_ON(cur->checked);
710 if (!list_empty(&cur->upper)) {
711 /*
712 * the backref was added previously when processsing
713 * backref of type BTRFS_TREE_BLOCK_REF_KEY
714 */
715 BUG_ON(!list_is_singular(&cur->upper));
716 edge = list_entry(cur->upper.next, struct backref_edge,
717 list[LOWER]);
718 BUG_ON(!list_empty(&edge->list[UPPER]));
719 exist = edge->node[UPPER];
720 /*
721 * add the upper level block to pending list if we need
722 * check its backrefs
723 */
724 if (!exist->checked)
725 list_add_tail(&edge->list[UPPER], &list);
726 } else {
727 exist = NULL;
728 }
729
730 while (1) {
731 cond_resched();
732 eb = path1->nodes[0];
733
734 if (ptr >= end) {
735 if (path1->slots[0] >= btrfs_header_nritems(eb)) {
736 ret = btrfs_next_leaf(rc->extent_root, path1);
737 if (ret < 0) {
738 err = ret;
739 goto out;
740 }
741 if (ret > 0)
742 break;
743 eb = path1->nodes[0];
744 }
745
746 btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
747 if (key.objectid != cur->bytenr) {
748 WARN_ON(exist);
749 break;
750 }
751
752 if (key.type == BTRFS_EXTENT_ITEM_KEY) {
753 ret = find_inline_backref(eb, path1->slots[0],
754 &ptr, &end);
755 if (ret)
756 goto next;
757 }
758 }
759
760 if (ptr < end) {
761 /* update key for inline back ref */
762 struct btrfs_extent_inline_ref *iref;
763 iref = (struct btrfs_extent_inline_ref *)ptr;
764 key.type = btrfs_extent_inline_ref_type(eb, iref);
765 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
766 WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
767 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
768 }
769
770 if (exist &&
771 ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
772 exist->owner == key.offset) ||
773 (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
774 exist->bytenr == key.offset))) {
775 exist = NULL;
776 goto next;
777 }
778
779 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
780 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
781 key.type == BTRFS_EXTENT_REF_V0_KEY) {
782 if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
783 struct btrfs_extent_ref_v0 *ref0;
784 ref0 = btrfs_item_ptr(eb, path1->slots[0],
785 struct btrfs_extent_ref_v0);
786 if (key.objectid == key.offset) {
787 root = find_tree_root(rc, eb, ref0);
788 if (root && !should_ignore_root(root))
789 cur->root = root;
790 else
791 list_add(&cur->list, &useless);
792 break;
793 }
794 if (is_cowonly_root(btrfs_ref_root_v0(eb,
795 ref0)))
796 cur->cowonly = 1;
797 }
798 #else
799 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
800 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
801 #endif
802 if (key.objectid == key.offset) {
803 /*
804 * only root blocks of reloc trees use
805 * backref of this type.
806 */
807 root = find_reloc_root(rc, cur->bytenr);
808 BUG_ON(!root);
809 cur->root = root;
810 break;
811 }
812
813 edge = alloc_backref_edge(cache);
814 if (!edge) {
815 err = -ENOMEM;
816 goto out;
817 }
818 rb_node = tree_search(&cache->rb_root, key.offset);
819 if (!rb_node) {
820 upper = alloc_backref_node(cache);
821 if (!upper) {
822 free_backref_edge(cache, edge);
823 err = -ENOMEM;
824 goto out;
825 }
826 upper->bytenr = key.offset;
827 upper->level = cur->level + 1;
828 /*
829 * backrefs for the upper level block isn't
830 * cached, add the block to pending list
831 */
832 list_add_tail(&edge->list[UPPER], &list);
833 } else {
834 upper = rb_entry(rb_node, struct backref_node,
835 rb_node);
836 BUG_ON(!upper->checked);
837 INIT_LIST_HEAD(&edge->list[UPPER]);
838 }
839 list_add_tail(&edge->list[LOWER], &cur->upper);
840 edge->node[LOWER] = cur;
841 edge->node[UPPER] = upper;
842
843 goto next;
844 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
845 goto next;
846 }
847
848 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
849 root = read_fs_root(rc->extent_root->fs_info, key.offset);
850 if (IS_ERR(root)) {
851 err = PTR_ERR(root);
852 goto out;
853 }
854
855 if (!root->ref_cows)
856 cur->cowonly = 1;
857
858 if (btrfs_root_level(&root->root_item) == cur->level) {
859 /* tree root */
860 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
861 cur->bytenr);
862 if (should_ignore_root(root))
863 list_add(&cur->list, &useless);
864 else
865 cur->root = root;
866 break;
867 }
868
869 level = cur->level + 1;
870
871 /*
872 * searching the tree to find upper level blocks
873 * reference the block.
874 */
875 path2->search_commit_root = 1;
876 path2->skip_locking = 1;
877 path2->lowest_level = level;
878 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
879 path2->lowest_level = 0;
880 if (ret < 0) {
881 err = ret;
882 goto out;
883 }
884 if (ret > 0 && path2->slots[level] > 0)
885 path2->slots[level]--;
886
887 eb = path2->nodes[level];
888 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
889 cur->bytenr);
890
891 lower = cur;
892 for (; level < BTRFS_MAX_LEVEL; level++) {
893 if (!path2->nodes[level]) {
894 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
895 lower->bytenr);
896 if (should_ignore_root(root))
897 list_add(&lower->list, &useless);
898 else
899 lower->root = root;
900 break;
901 }
902
903 edge = alloc_backref_edge(cache);
904 if (!edge) {
905 err = -ENOMEM;
906 goto out;
907 }
908
909 eb = path2->nodes[level];
910 rb_node = tree_search(&cache->rb_root, eb->start);
911 if (!rb_node) {
912 upper = alloc_backref_node(cache);
913 if (!upper) {
914 free_backref_edge(cache, edge);
915 err = -ENOMEM;
916 goto out;
917 }
918 upper->bytenr = eb->start;
919 upper->owner = btrfs_header_owner(eb);
920 upper->level = lower->level + 1;
921 if (!root->ref_cows)
922 upper->cowonly = 1;
923
924 /*
925 * if we know the block isn't shared
926 * we can void checking its backrefs.
927 */
928 if (btrfs_block_can_be_shared(root, eb))
929 upper->checked = 0;
930 else
931 upper->checked = 1;
932
933 /*
934 * add the block to pending list if we
935 * need check its backrefs. only block
936 * at 'cur->level + 1' is added to the
937 * tail of pending list. this guarantees
938 * we check backrefs from lower level
939 * blocks to upper level blocks.
940 */
941 if (!upper->checked &&
942 level == cur->level + 1) {
943 list_add_tail(&edge->list[UPPER],
944 &list);
945 } else
946 INIT_LIST_HEAD(&edge->list[UPPER]);
947 } else {
948 upper = rb_entry(rb_node, struct backref_node,
949 rb_node);
950 BUG_ON(!upper->checked);
951 INIT_LIST_HEAD(&edge->list[UPPER]);
952 if (!upper->owner)
953 upper->owner = btrfs_header_owner(eb);
954 }
955 list_add_tail(&edge->list[LOWER], &lower->upper);
956 edge->node[LOWER] = lower;
957 edge->node[UPPER] = upper;
958
959 if (rb_node)
960 break;
961 lower = upper;
962 upper = NULL;
963 }
964 btrfs_release_path(root, path2);
965 next:
966 if (ptr < end) {
967 ptr += btrfs_extent_inline_ref_size(key.type);
968 if (ptr >= end) {
969 WARN_ON(ptr > end);
970 ptr = 0;
971 end = 0;
972 }
973 }
974 if (ptr >= end)
975 path1->slots[0]++;
976 }
977 btrfs_release_path(rc->extent_root, path1);
978
979 cur->checked = 1;
980 WARN_ON(exist);
981
982 /* the pending list isn't empty, take the first block to process */
983 if (!list_empty(&list)) {
984 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
985 list_del_init(&edge->list[UPPER]);
986 cur = edge->node[UPPER];
987 goto again;
988 }
989
990 /*
991 * everything goes well, connect backref nodes and insert backref nodes
992 * into the cache.
993 */
994 BUG_ON(!node->checked);
995 cowonly = node->cowonly;
996 if (!cowonly) {
997 rb_node = tree_insert(&cache->rb_root, node->bytenr,
998 &node->rb_node);
999 BUG_ON(rb_node);
1000 list_add_tail(&node->lower, &cache->leaves);
1001 }
1002
1003 list_for_each_entry(edge, &node->upper, list[LOWER])
1004 list_add_tail(&edge->list[UPPER], &list);
1005
1006 while (!list_empty(&list)) {
1007 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1008 list_del_init(&edge->list[UPPER]);
1009 upper = edge->node[UPPER];
1010 if (upper->detached) {
1011 list_del(&edge->list[LOWER]);
1012 lower = edge->node[LOWER];
1013 free_backref_edge(cache, edge);
1014 if (list_empty(&lower->upper))
1015 list_add(&lower->list, &useless);
1016 continue;
1017 }
1018
1019 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1020 if (upper->lowest) {
1021 list_del_init(&upper->lower);
1022 upper->lowest = 0;
1023 }
1024
1025 list_add_tail(&edge->list[UPPER], &upper->lower);
1026 continue;
1027 }
1028
1029 BUG_ON(!upper->checked);
1030 BUG_ON(cowonly != upper->cowonly);
1031 if (!cowonly) {
1032 rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1033 &upper->rb_node);
1034 BUG_ON(rb_node);
1035 }
1036
1037 list_add_tail(&edge->list[UPPER], &upper->lower);
1038
1039 list_for_each_entry(edge, &upper->upper, list[LOWER])
1040 list_add_tail(&edge->list[UPPER], &list);
1041 }
1042 /*
1043 * process useless backref nodes. backref nodes for tree leaves
1044 * are deleted from the cache. backref nodes for upper level
1045 * tree blocks are left in the cache to avoid unnecessary backref
1046 * lookup.
1047 */
1048 while (!list_empty(&useless)) {
1049 upper = list_entry(useless.next, struct backref_node, list);
1050 list_del_init(&upper->list);
1051 BUG_ON(!list_empty(&upper->upper));
1052 if (upper == node)
1053 node = NULL;
1054 if (upper->lowest) {
1055 list_del_init(&upper->lower);
1056 upper->lowest = 0;
1057 }
1058 while (!list_empty(&upper->lower)) {
1059 edge = list_entry(upper->lower.next,
1060 struct backref_edge, list[UPPER]);
1061 list_del(&edge->list[UPPER]);
1062 list_del(&edge->list[LOWER]);
1063 lower = edge->node[LOWER];
1064 free_backref_edge(cache, edge);
1065
1066 if (list_empty(&lower->upper))
1067 list_add(&lower->list, &useless);
1068 }
1069 __mark_block_processed(rc, upper);
1070 if (upper->level > 0) {
1071 list_add(&upper->list, &cache->detached);
1072 upper->detached = 1;
1073 } else {
1074 rb_erase(&upper->rb_node, &cache->rb_root);
1075 free_backref_node(cache, upper);
1076 }
1077 }
1078 out:
1079 btrfs_free_path(path1);
1080 btrfs_free_path(path2);
1081 if (err) {
1082 while (!list_empty(&useless)) {
1083 lower = list_entry(useless.next,
1084 struct backref_node, upper);
1085 list_del_init(&lower->upper);
1086 }
1087 upper = node;
1088 INIT_LIST_HEAD(&list);
1089 while (upper) {
1090 if (RB_EMPTY_NODE(&upper->rb_node)) {
1091 list_splice_tail(&upper->upper, &list);
1092 free_backref_node(cache, upper);
1093 }
1094
1095 if (list_empty(&list))
1096 break;
1097
1098 edge = list_entry(list.next, struct backref_edge,
1099 list[LOWER]);
1100 list_del(&edge->list[LOWER]);
1101 upper = edge->node[UPPER];
1102 free_backref_edge(cache, edge);
1103 }
1104 return ERR_PTR(err);
1105 }
1106 BUG_ON(node && node->detached);
1107 return node;
1108 }
1109
1110 /*
1111 * helper to add backref node for the newly created snapshot.
1112 * the backref node is created by cloning backref node that
1113 * corresponds to root of source tree
1114 */
1115 static int clone_backref_node(struct btrfs_trans_handle *trans,
1116 struct reloc_control *rc,
1117 struct btrfs_root *src,
1118 struct btrfs_root *dest)
1119 {
1120 struct btrfs_root *reloc_root = src->reloc_root;
1121 struct backref_cache *cache = &rc->backref_cache;
1122 struct backref_node *node = NULL;
1123 struct backref_node *new_node;
1124 struct backref_edge *edge;
1125 struct backref_edge *new_edge;
1126 struct rb_node *rb_node;
1127
1128 if (cache->last_trans > 0)
1129 update_backref_cache(trans, cache);
1130
1131 rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1132 if (rb_node) {
1133 node = rb_entry(rb_node, struct backref_node, rb_node);
1134 if (node->detached)
1135 node = NULL;
1136 else
1137 BUG_ON(node->new_bytenr != reloc_root->node->start);
1138 }
1139
1140 if (!node) {
1141 rb_node = tree_search(&cache->rb_root,
1142 reloc_root->commit_root->start);
1143 if (rb_node) {
1144 node = rb_entry(rb_node, struct backref_node,
1145 rb_node);
1146 BUG_ON(node->detached);
1147 }
1148 }
1149
1150 if (!node)
1151 return 0;
1152
1153 new_node = alloc_backref_node(cache);
1154 if (!new_node)
1155 return -ENOMEM;
1156
1157 new_node->bytenr = dest->node->start;
1158 new_node->level = node->level;
1159 new_node->lowest = node->lowest;
1160 new_node->root = dest;
1161
1162 if (!node->lowest) {
1163 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1164 new_edge = alloc_backref_edge(cache);
1165 if (!new_edge)
1166 goto fail;
1167
1168 new_edge->node[UPPER] = new_node;
1169 new_edge->node[LOWER] = edge->node[LOWER];
1170 list_add_tail(&new_edge->list[UPPER],
1171 &new_node->lower);
1172 }
1173 }
1174
1175 rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1176 &new_node->rb_node);
1177 BUG_ON(rb_node);
1178
1179 if (!new_node->lowest) {
1180 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1181 list_add_tail(&new_edge->list[LOWER],
1182 &new_edge->node[LOWER]->upper);
1183 }
1184 }
1185 return 0;
1186 fail:
1187 while (!list_empty(&new_node->lower)) {
1188 new_edge = list_entry(new_node->lower.next,
1189 struct backref_edge, list[UPPER]);
1190 list_del(&new_edge->list[UPPER]);
1191 free_backref_edge(cache, new_edge);
1192 }
1193 free_backref_node(cache, new_node);
1194 return -ENOMEM;
1195 }
1196
1197 /*
1198 * helper to add 'address of tree root -> reloc tree' mapping
1199 */
1200 static int __add_reloc_root(struct btrfs_root *root)
1201 {
1202 struct rb_node *rb_node;
1203 struct mapping_node *node;
1204 struct reloc_control *rc = root->fs_info->reloc_ctl;
1205
1206 node = kmalloc(sizeof(*node), GFP_NOFS);
1207 BUG_ON(!node);
1208
1209 node->bytenr = root->node->start;
1210 node->data = root;
1211
1212 spin_lock(&rc->reloc_root_tree.lock);
1213 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1214 node->bytenr, &node->rb_node);
1215 spin_unlock(&rc->reloc_root_tree.lock);
1216 BUG_ON(rb_node);
1217
1218 list_add_tail(&root->root_list, &rc->reloc_roots);
1219 return 0;
1220 }
1221
1222 /*
1223 * helper to update/delete the 'address of tree root -> reloc tree'
1224 * mapping
1225 */
1226 static int __update_reloc_root(struct btrfs_root *root, int del)
1227 {
1228 struct rb_node *rb_node;
1229 struct mapping_node *node = NULL;
1230 struct reloc_control *rc = root->fs_info->reloc_ctl;
1231
1232 spin_lock(&rc->reloc_root_tree.lock);
1233 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1234 root->commit_root->start);
1235 if (rb_node) {
1236 node = rb_entry(rb_node, struct mapping_node, rb_node);
1237 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1238 }
1239 spin_unlock(&rc->reloc_root_tree.lock);
1240
1241 BUG_ON((struct btrfs_root *)node->data != root);
1242
1243 if (!del) {
1244 spin_lock(&rc->reloc_root_tree.lock);
1245 node->bytenr = root->node->start;
1246 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1247 node->bytenr, &node->rb_node);
1248 spin_unlock(&rc->reloc_root_tree.lock);
1249 BUG_ON(rb_node);
1250 } else {
1251 list_del_init(&root->root_list);
1252 kfree(node);
1253 }
1254 return 0;
1255 }
1256
1257 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1258 struct btrfs_root *root, u64 objectid)
1259 {
1260 struct btrfs_root *reloc_root;
1261 struct extent_buffer *eb;
1262 struct btrfs_root_item *root_item;
1263 struct btrfs_key root_key;
1264 int ret;
1265
1266 root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1267 BUG_ON(!root_item);
1268
1269 root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1270 root_key.type = BTRFS_ROOT_ITEM_KEY;
1271 root_key.offset = objectid;
1272
1273 if (root->root_key.objectid == objectid) {
1274 /* called by btrfs_init_reloc_root */
1275 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1276 BTRFS_TREE_RELOC_OBJECTID);
1277 BUG_ON(ret);
1278
1279 btrfs_set_root_last_snapshot(&root->root_item,
1280 trans->transid - 1);
1281 } else {
1282 /*
1283 * called by btrfs_reloc_post_snapshot_hook.
1284 * the source tree is a reloc tree, all tree blocks
1285 * modified after it was created have RELOC flag
1286 * set in their headers. so it's OK to not update
1287 * the 'last_snapshot'.
1288 */
1289 ret = btrfs_copy_root(trans, root, root->node, &eb,
1290 BTRFS_TREE_RELOC_OBJECTID);
1291 BUG_ON(ret);
1292 }
1293
1294 memcpy(root_item, &root->root_item, sizeof(*root_item));
1295 btrfs_set_root_bytenr(root_item, eb->start);
1296 btrfs_set_root_level(root_item, btrfs_header_level(eb));
1297 btrfs_set_root_generation(root_item, trans->transid);
1298
1299 if (root->root_key.objectid == objectid) {
1300 btrfs_set_root_refs(root_item, 0);
1301 memset(&root_item->drop_progress, 0,
1302 sizeof(struct btrfs_disk_key));
1303 root_item->drop_level = 0;
1304 }
1305
1306 btrfs_tree_unlock(eb);
1307 free_extent_buffer(eb);
1308
1309 ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1310 &root_key, root_item);
1311 BUG_ON(ret);
1312 kfree(root_item);
1313
1314 reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
1315 &root_key);
1316 BUG_ON(IS_ERR(reloc_root));
1317 reloc_root->last_trans = trans->transid;
1318 return reloc_root;
1319 }
1320
1321 /*
1322 * create reloc tree for a given fs tree. reloc tree is just a
1323 * snapshot of the fs tree with special root objectid.
1324 */
1325 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1326 struct btrfs_root *root)
1327 {
1328 struct btrfs_root *reloc_root;
1329 struct reloc_control *rc = root->fs_info->reloc_ctl;
1330 int clear_rsv = 0;
1331
1332 if (root->reloc_root) {
1333 reloc_root = root->reloc_root;
1334 reloc_root->last_trans = trans->transid;
1335 return 0;
1336 }
1337
1338 if (!rc || !rc->create_reloc_tree ||
1339 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1340 return 0;
1341
1342 if (!trans->block_rsv) {
1343 trans->block_rsv = rc->block_rsv;
1344 clear_rsv = 1;
1345 }
1346 reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1347 if (clear_rsv)
1348 trans->block_rsv = NULL;
1349
1350 __add_reloc_root(reloc_root);
1351 root->reloc_root = reloc_root;
1352 return 0;
1353 }
1354
1355 /*
1356 * update root item of reloc tree
1357 */
1358 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1359 struct btrfs_root *root)
1360 {
1361 struct btrfs_root *reloc_root;
1362 struct btrfs_root_item *root_item;
1363 int del = 0;
1364 int ret;
1365
1366 if (!root->reloc_root)
1367 return 0;
1368
1369 reloc_root = root->reloc_root;
1370 root_item = &reloc_root->root_item;
1371
1372 if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1373 btrfs_root_refs(root_item) == 0) {
1374 root->reloc_root = NULL;
1375 del = 1;
1376 }
1377
1378 __update_reloc_root(reloc_root, del);
1379
1380 if (reloc_root->commit_root != reloc_root->node) {
1381 btrfs_set_root_node(root_item, reloc_root->node);
1382 free_extent_buffer(reloc_root->commit_root);
1383 reloc_root->commit_root = btrfs_root_node(reloc_root);
1384 }
1385
1386 ret = btrfs_update_root(trans, root->fs_info->tree_root,
1387 &reloc_root->root_key, root_item);
1388 BUG_ON(ret);
1389 return 0;
1390 }
1391
1392 /*
1393 * helper to find first cached inode with inode number >= objectid
1394 * in a subvolume
1395 */
1396 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1397 {
1398 struct rb_node *node;
1399 struct rb_node *prev;
1400 struct btrfs_inode *entry;
1401 struct inode *inode;
1402
1403 spin_lock(&root->inode_lock);
1404 again:
1405 node = root->inode_tree.rb_node;
1406 prev = NULL;
1407 while (node) {
1408 prev = node;
1409 entry = rb_entry(node, struct btrfs_inode, rb_node);
1410
1411 if (objectid < entry->vfs_inode.i_ino)
1412 node = node->rb_left;
1413 else if (objectid > entry->vfs_inode.i_ino)
1414 node = node->rb_right;
1415 else
1416 break;
1417 }
1418 if (!node) {
1419 while (prev) {
1420 entry = rb_entry(prev, struct btrfs_inode, rb_node);
1421 if (objectid <= entry->vfs_inode.i_ino) {
1422 node = prev;
1423 break;
1424 }
1425 prev = rb_next(prev);
1426 }
1427 }
1428 while (node) {
1429 entry = rb_entry(node, struct btrfs_inode, rb_node);
1430 inode = igrab(&entry->vfs_inode);
1431 if (inode) {
1432 spin_unlock(&root->inode_lock);
1433 return inode;
1434 }
1435
1436 objectid = entry->vfs_inode.i_ino + 1;
1437 if (cond_resched_lock(&root->inode_lock))
1438 goto again;
1439
1440 node = rb_next(node);
1441 }
1442 spin_unlock(&root->inode_lock);
1443 return NULL;
1444 }
1445
1446 static int in_block_group(u64 bytenr,
1447 struct btrfs_block_group_cache *block_group)
1448 {
1449 if (bytenr >= block_group->key.objectid &&
1450 bytenr < block_group->key.objectid + block_group->key.offset)
1451 return 1;
1452 return 0;
1453 }
1454
1455 /*
1456 * get new location of data
1457 */
1458 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1459 u64 bytenr, u64 num_bytes)
1460 {
1461 struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1462 struct btrfs_path *path;
1463 struct btrfs_file_extent_item *fi;
1464 struct extent_buffer *leaf;
1465 int ret;
1466
1467 path = btrfs_alloc_path();
1468 if (!path)
1469 return -ENOMEM;
1470
1471 bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1472 ret = btrfs_lookup_file_extent(NULL, root, path, reloc_inode->i_ino,
1473 bytenr, 0);
1474 if (ret < 0)
1475 goto out;
1476 if (ret > 0) {
1477 ret = -ENOENT;
1478 goto out;
1479 }
1480
1481 leaf = path->nodes[0];
1482 fi = btrfs_item_ptr(leaf, path->slots[0],
1483 struct btrfs_file_extent_item);
1484
1485 BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1486 btrfs_file_extent_compression(leaf, fi) ||
1487 btrfs_file_extent_encryption(leaf, fi) ||
1488 btrfs_file_extent_other_encoding(leaf, fi));
1489
1490 if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1491 ret = 1;
1492 goto out;
1493 }
1494
1495 *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1496 ret = 0;
1497 out:
1498 btrfs_free_path(path);
1499 return ret;
1500 }
1501
1502 /*
1503 * update file extent items in the tree leaf to point to
1504 * the new locations.
1505 */
1506 static noinline_for_stack
1507 int replace_file_extents(struct btrfs_trans_handle *trans,
1508 struct reloc_control *rc,
1509 struct btrfs_root *root,
1510 struct extent_buffer *leaf)
1511 {
1512 struct btrfs_key key;
1513 struct btrfs_file_extent_item *fi;
1514 struct inode *inode = NULL;
1515 u64 parent;
1516 u64 bytenr;
1517 u64 new_bytenr = 0;
1518 u64 num_bytes;
1519 u64 end;
1520 u32 nritems;
1521 u32 i;
1522 int ret;
1523 int first = 1;
1524 int dirty = 0;
1525
1526 if (rc->stage != UPDATE_DATA_PTRS)
1527 return 0;
1528
1529 /* reloc trees always use full backref */
1530 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1531 parent = leaf->start;
1532 else
1533 parent = 0;
1534
1535 nritems = btrfs_header_nritems(leaf);
1536 for (i = 0; i < nritems; i++) {
1537 cond_resched();
1538 btrfs_item_key_to_cpu(leaf, &key, i);
1539 if (key.type != BTRFS_EXTENT_DATA_KEY)
1540 continue;
1541 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1542 if (btrfs_file_extent_type(leaf, fi) ==
1543 BTRFS_FILE_EXTENT_INLINE)
1544 continue;
1545 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1546 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1547 if (bytenr == 0)
1548 continue;
1549 if (!in_block_group(bytenr, rc->block_group))
1550 continue;
1551
1552 /*
1553 * if we are modifying block in fs tree, wait for readpage
1554 * to complete and drop the extent cache
1555 */
1556 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1557 if (first) {
1558 inode = find_next_inode(root, key.objectid);
1559 first = 0;
1560 } else if (inode && inode->i_ino < key.objectid) {
1561 btrfs_add_delayed_iput(inode);
1562 inode = find_next_inode(root, key.objectid);
1563 }
1564 if (inode && inode->i_ino == key.objectid) {
1565 end = key.offset +
1566 btrfs_file_extent_num_bytes(leaf, fi);
1567 WARN_ON(!IS_ALIGNED(key.offset,
1568 root->sectorsize));
1569 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1570 end--;
1571 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1572 key.offset, end,
1573 GFP_NOFS);
1574 if (!ret)
1575 continue;
1576
1577 btrfs_drop_extent_cache(inode, key.offset, end,
1578 1);
1579 unlock_extent(&BTRFS_I(inode)->io_tree,
1580 key.offset, end, GFP_NOFS);
1581 }
1582 }
1583
1584 ret = get_new_location(rc->data_inode, &new_bytenr,
1585 bytenr, num_bytes);
1586 if (ret > 0) {
1587 WARN_ON(1);
1588 continue;
1589 }
1590 BUG_ON(ret < 0);
1591
1592 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1593 dirty = 1;
1594
1595 key.offset -= btrfs_file_extent_offset(leaf, fi);
1596 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1597 num_bytes, parent,
1598 btrfs_header_owner(leaf),
1599 key.objectid, key.offset);
1600 BUG_ON(ret);
1601
1602 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1603 parent, btrfs_header_owner(leaf),
1604 key.objectid, key.offset);
1605 BUG_ON(ret);
1606 }
1607 if (dirty)
1608 btrfs_mark_buffer_dirty(leaf);
1609 if (inode)
1610 btrfs_add_delayed_iput(inode);
1611 return 0;
1612 }
1613
1614 static noinline_for_stack
1615 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1616 struct btrfs_path *path, int level)
1617 {
1618 struct btrfs_disk_key key1;
1619 struct btrfs_disk_key key2;
1620 btrfs_node_key(eb, &key1, slot);
1621 btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1622 return memcmp(&key1, &key2, sizeof(key1));
1623 }
1624
1625 /*
1626 * try to replace tree blocks in fs tree with the new blocks
1627 * in reloc tree. tree blocks haven't been modified since the
1628 * reloc tree was create can be replaced.
1629 *
1630 * if a block was replaced, level of the block + 1 is returned.
1631 * if no block got replaced, 0 is returned. if there are other
1632 * errors, a negative error number is returned.
1633 */
1634 static noinline_for_stack
1635 int replace_path(struct btrfs_trans_handle *trans,
1636 struct btrfs_root *dest, struct btrfs_root *src,
1637 struct btrfs_path *path, struct btrfs_key *next_key,
1638 int lowest_level, int max_level)
1639 {
1640 struct extent_buffer *eb;
1641 struct extent_buffer *parent;
1642 struct btrfs_key key;
1643 u64 old_bytenr;
1644 u64 new_bytenr;
1645 u64 old_ptr_gen;
1646 u64 new_ptr_gen;
1647 u64 last_snapshot;
1648 u32 blocksize;
1649 int cow = 0;
1650 int level;
1651 int ret;
1652 int slot;
1653
1654 BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1655 BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1656
1657 last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1658 again:
1659 slot = path->slots[lowest_level];
1660 btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1661
1662 eb = btrfs_lock_root_node(dest);
1663 btrfs_set_lock_blocking(eb);
1664 level = btrfs_header_level(eb);
1665
1666 if (level < lowest_level) {
1667 btrfs_tree_unlock(eb);
1668 free_extent_buffer(eb);
1669 return 0;
1670 }
1671
1672 if (cow) {
1673 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1674 BUG_ON(ret);
1675 }
1676 btrfs_set_lock_blocking(eb);
1677
1678 if (next_key) {
1679 next_key->objectid = (u64)-1;
1680 next_key->type = (u8)-1;
1681 next_key->offset = (u64)-1;
1682 }
1683
1684 parent = eb;
1685 while (1) {
1686 level = btrfs_header_level(parent);
1687 BUG_ON(level < lowest_level);
1688
1689 ret = btrfs_bin_search(parent, &key, level, &slot);
1690 if (ret && slot > 0)
1691 slot--;
1692
1693 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1694 btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1695
1696 old_bytenr = btrfs_node_blockptr(parent, slot);
1697 blocksize = btrfs_level_size(dest, level - 1);
1698 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1699
1700 if (level <= max_level) {
1701 eb = path->nodes[level];
1702 new_bytenr = btrfs_node_blockptr(eb,
1703 path->slots[level]);
1704 new_ptr_gen = btrfs_node_ptr_generation(eb,
1705 path->slots[level]);
1706 } else {
1707 new_bytenr = 0;
1708 new_ptr_gen = 0;
1709 }
1710
1711 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1712 WARN_ON(1);
1713 ret = level;
1714 break;
1715 }
1716
1717 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1718 memcmp_node_keys(parent, slot, path, level)) {
1719 if (level <= lowest_level) {
1720 ret = 0;
1721 break;
1722 }
1723
1724 eb = read_tree_block(dest, old_bytenr, blocksize,
1725 old_ptr_gen);
1726 btrfs_tree_lock(eb);
1727 if (cow) {
1728 ret = btrfs_cow_block(trans, dest, eb, parent,
1729 slot, &eb);
1730 BUG_ON(ret);
1731 }
1732 btrfs_set_lock_blocking(eb);
1733
1734 btrfs_tree_unlock(parent);
1735 free_extent_buffer(parent);
1736
1737 parent = eb;
1738 continue;
1739 }
1740
1741 if (!cow) {
1742 btrfs_tree_unlock(parent);
1743 free_extent_buffer(parent);
1744 cow = 1;
1745 goto again;
1746 }
1747
1748 btrfs_node_key_to_cpu(path->nodes[level], &key,
1749 path->slots[level]);
1750 btrfs_release_path(src, path);
1751
1752 path->lowest_level = level;
1753 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1754 path->lowest_level = 0;
1755 BUG_ON(ret);
1756
1757 /*
1758 * swap blocks in fs tree and reloc tree.
1759 */
1760 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1761 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1762 btrfs_mark_buffer_dirty(parent);
1763
1764 btrfs_set_node_blockptr(path->nodes[level],
1765 path->slots[level], old_bytenr);
1766 btrfs_set_node_ptr_generation(path->nodes[level],
1767 path->slots[level], old_ptr_gen);
1768 btrfs_mark_buffer_dirty(path->nodes[level]);
1769
1770 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1771 path->nodes[level]->start,
1772 src->root_key.objectid, level - 1, 0);
1773 BUG_ON(ret);
1774 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1775 0, dest->root_key.objectid, level - 1,
1776 0);
1777 BUG_ON(ret);
1778
1779 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1780 path->nodes[level]->start,
1781 src->root_key.objectid, level - 1, 0);
1782 BUG_ON(ret);
1783
1784 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1785 0, dest->root_key.objectid, level - 1,
1786 0);
1787 BUG_ON(ret);
1788
1789 btrfs_unlock_up_safe(path, 0);
1790
1791 ret = level;
1792 break;
1793 }
1794 btrfs_tree_unlock(parent);
1795 free_extent_buffer(parent);
1796 return ret;
1797 }
1798
1799 /*
1800 * helper to find next relocated block in reloc tree
1801 */
1802 static noinline_for_stack
1803 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1804 int *level)
1805 {
1806 struct extent_buffer *eb;
1807 int i;
1808 u64 last_snapshot;
1809 u32 nritems;
1810
1811 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1812
1813 for (i = 0; i < *level; i++) {
1814 free_extent_buffer(path->nodes[i]);
1815 path->nodes[i] = NULL;
1816 }
1817
1818 for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1819 eb = path->nodes[i];
1820 nritems = btrfs_header_nritems(eb);
1821 while (path->slots[i] + 1 < nritems) {
1822 path->slots[i]++;
1823 if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1824 last_snapshot)
1825 continue;
1826
1827 *level = i;
1828 return 0;
1829 }
1830 free_extent_buffer(path->nodes[i]);
1831 path->nodes[i] = NULL;
1832 }
1833 return 1;
1834 }
1835
1836 /*
1837 * walk down reloc tree to find relocated block of lowest level
1838 */
1839 static noinline_for_stack
1840 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1841 int *level)
1842 {
1843 struct extent_buffer *eb = NULL;
1844 int i;
1845 u64 bytenr;
1846 u64 ptr_gen = 0;
1847 u64 last_snapshot;
1848 u32 blocksize;
1849 u32 nritems;
1850
1851 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1852
1853 for (i = *level; i > 0; i--) {
1854 eb = path->nodes[i];
1855 nritems = btrfs_header_nritems(eb);
1856 while (path->slots[i] < nritems) {
1857 ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1858 if (ptr_gen > last_snapshot)
1859 break;
1860 path->slots[i]++;
1861 }
1862 if (path->slots[i] >= nritems) {
1863 if (i == *level)
1864 break;
1865 *level = i + 1;
1866 return 0;
1867 }
1868 if (i == 1) {
1869 *level = i;
1870 return 0;
1871 }
1872
1873 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1874 blocksize = btrfs_level_size(root, i - 1);
1875 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1876 BUG_ON(btrfs_header_level(eb) != i - 1);
1877 path->nodes[i - 1] = eb;
1878 path->slots[i - 1] = 0;
1879 }
1880 return 1;
1881 }
1882
1883 /*
1884 * invalidate extent cache for file extents whose key in range of
1885 * [min_key, max_key)
1886 */
1887 static int invalidate_extent_cache(struct btrfs_root *root,
1888 struct btrfs_key *min_key,
1889 struct btrfs_key *max_key)
1890 {
1891 struct inode *inode = NULL;
1892 u64 objectid;
1893 u64 start, end;
1894
1895 objectid = min_key->objectid;
1896 while (1) {
1897 cond_resched();
1898 iput(inode);
1899
1900 if (objectid > max_key->objectid)
1901 break;
1902
1903 inode = find_next_inode(root, objectid);
1904 if (!inode)
1905 break;
1906
1907 if (inode->i_ino > max_key->objectid) {
1908 iput(inode);
1909 break;
1910 }
1911
1912 objectid = inode->i_ino + 1;
1913 if (!S_ISREG(inode->i_mode))
1914 continue;
1915
1916 if (unlikely(min_key->objectid == inode->i_ino)) {
1917 if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1918 continue;
1919 if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1920 start = 0;
1921 else {
1922 start = min_key->offset;
1923 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1924 }
1925 } else {
1926 start = 0;
1927 }
1928
1929 if (unlikely(max_key->objectid == inode->i_ino)) {
1930 if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1931 continue;
1932 if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1933 end = (u64)-1;
1934 } else {
1935 if (max_key->offset == 0)
1936 continue;
1937 end = max_key->offset;
1938 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1939 end--;
1940 }
1941 } else {
1942 end = (u64)-1;
1943 }
1944
1945 /* the lock_extent waits for readpage to complete */
1946 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1947 btrfs_drop_extent_cache(inode, start, end, 1);
1948 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1949 }
1950 return 0;
1951 }
1952
1953 static int find_next_key(struct btrfs_path *path, int level,
1954 struct btrfs_key *key)
1955
1956 {
1957 while (level < BTRFS_MAX_LEVEL) {
1958 if (!path->nodes[level])
1959 break;
1960 if (path->slots[level] + 1 <
1961 btrfs_header_nritems(path->nodes[level])) {
1962 btrfs_node_key_to_cpu(path->nodes[level], key,
1963 path->slots[level] + 1);
1964 return 0;
1965 }
1966 level++;
1967 }
1968 return 1;
1969 }
1970
1971 /*
1972 * merge the relocated tree blocks in reloc tree with corresponding
1973 * fs tree.
1974 */
1975 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
1976 struct btrfs_root *root)
1977 {
1978 LIST_HEAD(inode_list);
1979 struct btrfs_key key;
1980 struct btrfs_key next_key;
1981 struct btrfs_trans_handle *trans;
1982 struct btrfs_root *reloc_root;
1983 struct btrfs_root_item *root_item;
1984 struct btrfs_path *path;
1985 struct extent_buffer *leaf;
1986 unsigned long nr;
1987 int level;
1988 int max_level;
1989 int replaced = 0;
1990 int ret;
1991 int err = 0;
1992 u32 min_reserved;
1993
1994 path = btrfs_alloc_path();
1995 if (!path)
1996 return -ENOMEM;
1997
1998 reloc_root = root->reloc_root;
1999 root_item = &reloc_root->root_item;
2000
2001 if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2002 level = btrfs_root_level(root_item);
2003 extent_buffer_get(reloc_root->node);
2004 path->nodes[level] = reloc_root->node;
2005 path->slots[level] = 0;
2006 } else {
2007 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2008
2009 level = root_item->drop_level;
2010 BUG_ON(level == 0);
2011 path->lowest_level = level;
2012 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2013 path->lowest_level = 0;
2014 if (ret < 0) {
2015 btrfs_free_path(path);
2016 return ret;
2017 }
2018
2019 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2020 path->slots[level]);
2021 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2022
2023 btrfs_unlock_up_safe(path, 0);
2024 }
2025
2026 min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2027 memset(&next_key, 0, sizeof(next_key));
2028
2029 while (1) {
2030 trans = btrfs_start_transaction(root, 0);
2031 trans->block_rsv = rc->block_rsv;
2032
2033 ret = btrfs_block_rsv_check(trans, root, rc->block_rsv,
2034 min_reserved, 0);
2035 if (ret) {
2036 BUG_ON(ret != -EAGAIN);
2037 ret = btrfs_commit_transaction(trans, root);
2038 BUG_ON(ret);
2039 continue;
2040 }
2041
2042 replaced = 0;
2043 max_level = level;
2044
2045 ret = walk_down_reloc_tree(reloc_root, path, &level);
2046 if (ret < 0) {
2047 err = ret;
2048 goto out;
2049 }
2050 if (ret > 0)
2051 break;
2052
2053 if (!find_next_key(path, level, &key) &&
2054 btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2055 ret = 0;
2056 } else {
2057 ret = replace_path(trans, root, reloc_root, path,
2058 &next_key, level, max_level);
2059 }
2060 if (ret < 0) {
2061 err = ret;
2062 goto out;
2063 }
2064
2065 if (ret > 0) {
2066 level = ret;
2067 btrfs_node_key_to_cpu(path->nodes[level], &key,
2068 path->slots[level]);
2069 replaced = 1;
2070 }
2071
2072 ret = walk_up_reloc_tree(reloc_root, path, &level);
2073 if (ret > 0)
2074 break;
2075
2076 BUG_ON(level == 0);
2077 /*
2078 * save the merging progress in the drop_progress.
2079 * this is OK since root refs == 1 in this case.
2080 */
2081 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2082 path->slots[level]);
2083 root_item->drop_level = level;
2084
2085 nr = trans->blocks_used;
2086 btrfs_end_transaction_throttle(trans, root);
2087
2088 btrfs_btree_balance_dirty(root, nr);
2089
2090 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2091 invalidate_extent_cache(root, &key, &next_key);
2092 }
2093
2094 /*
2095 * handle the case only one block in the fs tree need to be
2096 * relocated and the block is tree root.
2097 */
2098 leaf = btrfs_lock_root_node(root);
2099 ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2100 btrfs_tree_unlock(leaf);
2101 free_extent_buffer(leaf);
2102 if (ret < 0)
2103 err = ret;
2104 out:
2105 btrfs_free_path(path);
2106
2107 if (err == 0) {
2108 memset(&root_item->drop_progress, 0,
2109 sizeof(root_item->drop_progress));
2110 root_item->drop_level = 0;
2111 btrfs_set_root_refs(root_item, 0);
2112 btrfs_update_reloc_root(trans, root);
2113 }
2114
2115 nr = trans->blocks_used;
2116 btrfs_end_transaction_throttle(trans, root);
2117
2118 btrfs_btree_balance_dirty(root, nr);
2119
2120 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2121 invalidate_extent_cache(root, &key, &next_key);
2122
2123 return err;
2124 }
2125
2126 static noinline_for_stack
2127 int prepare_to_merge(struct reloc_control *rc, int err)
2128 {
2129 struct btrfs_root *root = rc->extent_root;
2130 struct btrfs_root *reloc_root;
2131 struct btrfs_trans_handle *trans;
2132 LIST_HEAD(reloc_roots);
2133 u64 num_bytes = 0;
2134 int ret;
2135
2136 mutex_lock(&root->fs_info->trans_mutex);
2137 rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2138 rc->merging_rsv_size += rc->nodes_relocated * 2;
2139 mutex_unlock(&root->fs_info->trans_mutex);
2140 again:
2141 if (!err) {
2142 num_bytes = rc->merging_rsv_size;
2143 ret = btrfs_block_rsv_add(NULL, root, rc->block_rsv,
2144 num_bytes);
2145 if (ret)
2146 err = ret;
2147 }
2148
2149 trans = btrfs_join_transaction(rc->extent_root, 1);
2150
2151 if (!err) {
2152 if (num_bytes != rc->merging_rsv_size) {
2153 btrfs_end_transaction(trans, rc->extent_root);
2154 btrfs_block_rsv_release(rc->extent_root,
2155 rc->block_rsv, num_bytes);
2156 goto again;
2157 }
2158 }
2159
2160 rc->merge_reloc_tree = 1;
2161
2162 while (!list_empty(&rc->reloc_roots)) {
2163 reloc_root = list_entry(rc->reloc_roots.next,
2164 struct btrfs_root, root_list);
2165 list_del_init(&reloc_root->root_list);
2166
2167 root = read_fs_root(reloc_root->fs_info,
2168 reloc_root->root_key.offset);
2169 BUG_ON(IS_ERR(root));
2170 BUG_ON(root->reloc_root != reloc_root);
2171
2172 /*
2173 * set reference count to 1, so btrfs_recover_relocation
2174 * knows it should resumes merging
2175 */
2176 if (!err)
2177 btrfs_set_root_refs(&reloc_root->root_item, 1);
2178 btrfs_update_reloc_root(trans, root);
2179
2180 list_add(&reloc_root->root_list, &reloc_roots);
2181 }
2182
2183 list_splice(&reloc_roots, &rc->reloc_roots);
2184
2185 if (!err)
2186 btrfs_commit_transaction(trans, rc->extent_root);
2187 else
2188 btrfs_end_transaction(trans, rc->extent_root);
2189 return err;
2190 }
2191
2192 static noinline_for_stack
2193 int merge_reloc_roots(struct reloc_control *rc)
2194 {
2195 struct btrfs_root *root;
2196 struct btrfs_root *reloc_root;
2197 LIST_HEAD(reloc_roots);
2198 int found = 0;
2199 int ret;
2200 again:
2201 root = rc->extent_root;
2202 mutex_lock(&root->fs_info->trans_mutex);
2203 list_splice_init(&rc->reloc_roots, &reloc_roots);
2204 mutex_unlock(&root->fs_info->trans_mutex);
2205
2206 while (!list_empty(&reloc_roots)) {
2207 found = 1;
2208 reloc_root = list_entry(reloc_roots.next,
2209 struct btrfs_root, root_list);
2210
2211 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2212 root = read_fs_root(reloc_root->fs_info,
2213 reloc_root->root_key.offset);
2214 BUG_ON(IS_ERR(root));
2215 BUG_ON(root->reloc_root != reloc_root);
2216
2217 ret = merge_reloc_root(rc, root);
2218 BUG_ON(ret);
2219 } else {
2220 list_del_init(&reloc_root->root_list);
2221 }
2222 btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
2223 }
2224
2225 if (found) {
2226 found = 0;
2227 goto again;
2228 }
2229 BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2230 return 0;
2231 }
2232
2233 static void free_block_list(struct rb_root *blocks)
2234 {
2235 struct tree_block *block;
2236 struct rb_node *rb_node;
2237 while ((rb_node = rb_first(blocks))) {
2238 block = rb_entry(rb_node, struct tree_block, rb_node);
2239 rb_erase(rb_node, blocks);
2240 kfree(block);
2241 }
2242 }
2243
2244 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2245 struct btrfs_root *reloc_root)
2246 {
2247 struct btrfs_root *root;
2248
2249 if (reloc_root->last_trans == trans->transid)
2250 return 0;
2251
2252 root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2253 BUG_ON(IS_ERR(root));
2254 BUG_ON(root->reloc_root != reloc_root);
2255
2256 return btrfs_record_root_in_trans(trans, root);
2257 }
2258
2259 static noinline_for_stack
2260 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2261 struct reloc_control *rc,
2262 struct backref_node *node,
2263 struct backref_edge *edges[], int *nr)
2264 {
2265 struct backref_node *next;
2266 struct btrfs_root *root;
2267 int index = 0;
2268
2269 next = node;
2270 while (1) {
2271 cond_resched();
2272 next = walk_up_backref(next, edges, &index);
2273 root = next->root;
2274 BUG_ON(!root);
2275 BUG_ON(!root->ref_cows);
2276
2277 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2278 record_reloc_root_in_trans(trans, root);
2279 break;
2280 }
2281
2282 btrfs_record_root_in_trans(trans, root);
2283 root = root->reloc_root;
2284
2285 if (next->new_bytenr != root->node->start) {
2286 BUG_ON(next->new_bytenr);
2287 BUG_ON(!list_empty(&next->list));
2288 next->new_bytenr = root->node->start;
2289 next->root = root;
2290 list_add_tail(&next->list,
2291 &rc->backref_cache.changed);
2292 __mark_block_processed(rc, next);
2293 break;
2294 }
2295
2296 WARN_ON(1);
2297 root = NULL;
2298 next = walk_down_backref(edges, &index);
2299 if (!next || next->level <= node->level)
2300 break;
2301 }
2302 if (!root)
2303 return NULL;
2304
2305 *nr = index;
2306 next = node;
2307 /* setup backref node path for btrfs_reloc_cow_block */
2308 while (1) {
2309 rc->backref_cache.path[next->level] = next;
2310 if (--index < 0)
2311 break;
2312 next = edges[index]->node[UPPER];
2313 }
2314 return root;
2315 }
2316
2317 /*
2318 * select a tree root for relocation. return NULL if the block
2319 * is reference counted. we should use do_relocation() in this
2320 * case. return a tree root pointer if the block isn't reference
2321 * counted. return -ENOENT if the block is root of reloc tree.
2322 */
2323 static noinline_for_stack
2324 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2325 struct backref_node *node)
2326 {
2327 struct backref_node *next;
2328 struct btrfs_root *root;
2329 struct btrfs_root *fs_root = NULL;
2330 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2331 int index = 0;
2332
2333 next = node;
2334 while (1) {
2335 cond_resched();
2336 next = walk_up_backref(next, edges, &index);
2337 root = next->root;
2338 BUG_ON(!root);
2339
2340 /* no other choice for non-refernce counted tree */
2341 if (!root->ref_cows)
2342 return root;
2343
2344 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2345 fs_root = root;
2346
2347 if (next != node)
2348 return NULL;
2349
2350 next = walk_down_backref(edges, &index);
2351 if (!next || next->level <= node->level)
2352 break;
2353 }
2354
2355 if (!fs_root)
2356 return ERR_PTR(-ENOENT);
2357 return fs_root;
2358 }
2359
2360 static noinline_for_stack
2361 u64 calcu_metadata_size(struct reloc_control *rc,
2362 struct backref_node *node, int reserve)
2363 {
2364 struct backref_node *next = node;
2365 struct backref_edge *edge;
2366 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2367 u64 num_bytes = 0;
2368 int index = 0;
2369
2370 BUG_ON(reserve && node->processed);
2371
2372 while (next) {
2373 cond_resched();
2374 while (1) {
2375 if (next->processed && (reserve || next != node))
2376 break;
2377
2378 num_bytes += btrfs_level_size(rc->extent_root,
2379 next->level);
2380
2381 if (list_empty(&next->upper))
2382 break;
2383
2384 edge = list_entry(next->upper.next,
2385 struct backref_edge, list[LOWER]);
2386 edges[index++] = edge;
2387 next = edge->node[UPPER];
2388 }
2389 next = walk_down_backref(edges, &index);
2390 }
2391 return num_bytes;
2392 }
2393
2394 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2395 struct reloc_control *rc,
2396 struct backref_node *node)
2397 {
2398 struct btrfs_root *root = rc->extent_root;
2399 u64 num_bytes;
2400 int ret;
2401
2402 num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2403
2404 trans->block_rsv = rc->block_rsv;
2405 ret = btrfs_block_rsv_add(trans, root, rc->block_rsv, num_bytes);
2406 if (ret) {
2407 if (ret == -EAGAIN)
2408 rc->commit_transaction = 1;
2409 return ret;
2410 }
2411
2412 return 0;
2413 }
2414
2415 static void release_metadata_space(struct reloc_control *rc,
2416 struct backref_node *node)
2417 {
2418 u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2419 btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2420 }
2421
2422 /*
2423 * relocate a block tree, and then update pointers in upper level
2424 * blocks that reference the block to point to the new location.
2425 *
2426 * if called by link_to_upper, the block has already been relocated.
2427 * in that case this function just updates pointers.
2428 */
2429 static int do_relocation(struct btrfs_trans_handle *trans,
2430 struct reloc_control *rc,
2431 struct backref_node *node,
2432 struct btrfs_key *key,
2433 struct btrfs_path *path, int lowest)
2434 {
2435 struct backref_node *upper;
2436 struct backref_edge *edge;
2437 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2438 struct btrfs_root *root;
2439 struct extent_buffer *eb;
2440 u32 blocksize;
2441 u64 bytenr;
2442 u64 generation;
2443 int nr;
2444 int slot;
2445 int ret;
2446 int err = 0;
2447
2448 BUG_ON(lowest && node->eb);
2449
2450 path->lowest_level = node->level + 1;
2451 rc->backref_cache.path[node->level] = node;
2452 list_for_each_entry(edge, &node->upper, list[LOWER]) {
2453 cond_resched();
2454
2455 upper = edge->node[UPPER];
2456 root = select_reloc_root(trans, rc, upper, edges, &nr);
2457 BUG_ON(!root);
2458
2459 if (upper->eb && !upper->locked) {
2460 if (!lowest) {
2461 ret = btrfs_bin_search(upper->eb, key,
2462 upper->level, &slot);
2463 BUG_ON(ret);
2464 bytenr = btrfs_node_blockptr(upper->eb, slot);
2465 if (node->eb->start == bytenr)
2466 goto next;
2467 }
2468 drop_node_buffer(upper);
2469 }
2470
2471 if (!upper->eb) {
2472 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2473 if (ret < 0) {
2474 err = ret;
2475 break;
2476 }
2477 BUG_ON(ret > 0);
2478
2479 if (!upper->eb) {
2480 upper->eb = path->nodes[upper->level];
2481 path->nodes[upper->level] = NULL;
2482 } else {
2483 BUG_ON(upper->eb != path->nodes[upper->level]);
2484 }
2485
2486 upper->locked = 1;
2487 path->locks[upper->level] = 0;
2488
2489 slot = path->slots[upper->level];
2490 btrfs_release_path(NULL, path);
2491 } else {
2492 ret = btrfs_bin_search(upper->eb, key, upper->level,
2493 &slot);
2494 BUG_ON(ret);
2495 }
2496
2497 bytenr = btrfs_node_blockptr(upper->eb, slot);
2498 if (lowest) {
2499 BUG_ON(bytenr != node->bytenr);
2500 } else {
2501 if (node->eb->start == bytenr)
2502 goto next;
2503 }
2504
2505 blocksize = btrfs_level_size(root, node->level);
2506 generation = btrfs_node_ptr_generation(upper->eb, slot);
2507 eb = read_tree_block(root, bytenr, blocksize, generation);
2508 btrfs_tree_lock(eb);
2509 btrfs_set_lock_blocking(eb);
2510
2511 if (!node->eb) {
2512 ret = btrfs_cow_block(trans, root, eb, upper->eb,
2513 slot, &eb);
2514 btrfs_tree_unlock(eb);
2515 free_extent_buffer(eb);
2516 if (ret < 0) {
2517 err = ret;
2518 goto next;
2519 }
2520 BUG_ON(node->eb != eb);
2521 } else {
2522 btrfs_set_node_blockptr(upper->eb, slot,
2523 node->eb->start);
2524 btrfs_set_node_ptr_generation(upper->eb, slot,
2525 trans->transid);
2526 btrfs_mark_buffer_dirty(upper->eb);
2527
2528 ret = btrfs_inc_extent_ref(trans, root,
2529 node->eb->start, blocksize,
2530 upper->eb->start,
2531 btrfs_header_owner(upper->eb),
2532 node->level, 0);
2533 BUG_ON(ret);
2534
2535 ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2536 BUG_ON(ret);
2537 }
2538 next:
2539 if (!upper->pending)
2540 drop_node_buffer(upper);
2541 else
2542 unlock_node_buffer(upper);
2543 if (err)
2544 break;
2545 }
2546
2547 if (!err && node->pending) {
2548 drop_node_buffer(node);
2549 list_move_tail(&node->list, &rc->backref_cache.changed);
2550 node->pending = 0;
2551 }
2552
2553 path->lowest_level = 0;
2554 BUG_ON(err == -ENOSPC);
2555 return err;
2556 }
2557
2558 static int link_to_upper(struct btrfs_trans_handle *trans,
2559 struct reloc_control *rc,
2560 struct backref_node *node,
2561 struct btrfs_path *path)
2562 {
2563 struct btrfs_key key;
2564
2565 btrfs_node_key_to_cpu(node->eb, &key, 0);
2566 return do_relocation(trans, rc, node, &key, path, 0);
2567 }
2568
2569 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2570 struct reloc_control *rc,
2571 struct btrfs_path *path, int err)
2572 {
2573 LIST_HEAD(list);
2574 struct backref_cache *cache = &rc->backref_cache;
2575 struct backref_node *node;
2576 int level;
2577 int ret;
2578
2579 for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2580 while (!list_empty(&cache->pending[level])) {
2581 node = list_entry(cache->pending[level].next,
2582 struct backref_node, list);
2583 list_move_tail(&node->list, &list);
2584 BUG_ON(!node->pending);
2585
2586 if (!err) {
2587 ret = link_to_upper(trans, rc, node, path);
2588 if (ret < 0)
2589 err = ret;
2590 }
2591 }
2592 list_splice_init(&list, &cache->pending[level]);
2593 }
2594 return err;
2595 }
2596
2597 static void mark_block_processed(struct reloc_control *rc,
2598 u64 bytenr, u32 blocksize)
2599 {
2600 set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2601 EXTENT_DIRTY, GFP_NOFS);
2602 }
2603
2604 static void __mark_block_processed(struct reloc_control *rc,
2605 struct backref_node *node)
2606 {
2607 u32 blocksize;
2608 if (node->level == 0 ||
2609 in_block_group(node->bytenr, rc->block_group)) {
2610 blocksize = btrfs_level_size(rc->extent_root, node->level);
2611 mark_block_processed(rc, node->bytenr, blocksize);
2612 }
2613 node->processed = 1;
2614 }
2615
2616 /*
2617 * mark a block and all blocks directly/indirectly reference the block
2618 * as processed.
2619 */
2620 static void update_processed_blocks(struct reloc_control *rc,
2621 struct backref_node *node)
2622 {
2623 struct backref_node *next = node;
2624 struct backref_edge *edge;
2625 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2626 int index = 0;
2627
2628 while (next) {
2629 cond_resched();
2630 while (1) {
2631 if (next->processed)
2632 break;
2633
2634 __mark_block_processed(rc, next);
2635
2636 if (list_empty(&next->upper))
2637 break;
2638
2639 edge = list_entry(next->upper.next,
2640 struct backref_edge, list[LOWER]);
2641 edges[index++] = edge;
2642 next = edge->node[UPPER];
2643 }
2644 next = walk_down_backref(edges, &index);
2645 }
2646 }
2647
2648 static int tree_block_processed(u64 bytenr, u32 blocksize,
2649 struct reloc_control *rc)
2650 {
2651 if (test_range_bit(&rc->processed_blocks, bytenr,
2652 bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2653 return 1;
2654 return 0;
2655 }
2656
2657 static int get_tree_block_key(struct reloc_control *rc,
2658 struct tree_block *block)
2659 {
2660 struct extent_buffer *eb;
2661
2662 BUG_ON(block->key_ready);
2663 eb = read_tree_block(rc->extent_root, block->bytenr,
2664 block->key.objectid, block->key.offset);
2665 WARN_ON(btrfs_header_level(eb) != block->level);
2666 if (block->level == 0)
2667 btrfs_item_key_to_cpu(eb, &block->key, 0);
2668 else
2669 btrfs_node_key_to_cpu(eb, &block->key, 0);
2670 free_extent_buffer(eb);
2671 block->key_ready = 1;
2672 return 0;
2673 }
2674
2675 static int reada_tree_block(struct reloc_control *rc,
2676 struct tree_block *block)
2677 {
2678 BUG_ON(block->key_ready);
2679 readahead_tree_block(rc->extent_root, block->bytenr,
2680 block->key.objectid, block->key.offset);
2681 return 0;
2682 }
2683
2684 /*
2685 * helper function to relocate a tree block
2686 */
2687 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2688 struct reloc_control *rc,
2689 struct backref_node *node,
2690 struct btrfs_key *key,
2691 struct btrfs_path *path)
2692 {
2693 struct btrfs_root *root;
2694 int release = 0;
2695 int ret = 0;
2696
2697 if (!node)
2698 return 0;
2699
2700 BUG_ON(node->processed);
2701 root = select_one_root(trans, node);
2702 if (root == ERR_PTR(-ENOENT)) {
2703 update_processed_blocks(rc, node);
2704 goto out;
2705 }
2706
2707 if (!root || root->ref_cows) {
2708 ret = reserve_metadata_space(trans, rc, node);
2709 if (ret)
2710 goto out;
2711 release = 1;
2712 }
2713
2714 if (root) {
2715 if (root->ref_cows) {
2716 BUG_ON(node->new_bytenr);
2717 BUG_ON(!list_empty(&node->list));
2718 btrfs_record_root_in_trans(trans, root);
2719 root = root->reloc_root;
2720 node->new_bytenr = root->node->start;
2721 node->root = root;
2722 list_add_tail(&node->list, &rc->backref_cache.changed);
2723 } else {
2724 path->lowest_level = node->level;
2725 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2726 btrfs_release_path(root, path);
2727 if (ret > 0)
2728 ret = 0;
2729 }
2730 if (!ret)
2731 update_processed_blocks(rc, node);
2732 } else {
2733 ret = do_relocation(trans, rc, node, key, path, 1);
2734 }
2735 out:
2736 if (ret || node->level == 0 || node->cowonly) {
2737 if (release)
2738 release_metadata_space(rc, node);
2739 remove_backref_node(&rc->backref_cache, node);
2740 }
2741 return ret;
2742 }
2743
2744 /*
2745 * relocate a list of blocks
2746 */
2747 static noinline_for_stack
2748 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2749 struct reloc_control *rc, struct rb_root *blocks)
2750 {
2751 struct backref_node *node;
2752 struct btrfs_path *path;
2753 struct tree_block *block;
2754 struct rb_node *rb_node;
2755 int ret;
2756 int err = 0;
2757
2758 path = btrfs_alloc_path();
2759 if (!path)
2760 return -ENOMEM;
2761
2762 rb_node = rb_first(blocks);
2763 while (rb_node) {
2764 block = rb_entry(rb_node, struct tree_block, rb_node);
2765 if (!block->key_ready)
2766 reada_tree_block(rc, block);
2767 rb_node = rb_next(rb_node);
2768 }
2769
2770 rb_node = rb_first(blocks);
2771 while (rb_node) {
2772 block = rb_entry(rb_node, struct tree_block, rb_node);
2773 if (!block->key_ready)
2774 get_tree_block_key(rc, block);
2775 rb_node = rb_next(rb_node);
2776 }
2777
2778 rb_node = rb_first(blocks);
2779 while (rb_node) {
2780 block = rb_entry(rb_node, struct tree_block, rb_node);
2781
2782 node = build_backref_tree(rc, &block->key,
2783 block->level, block->bytenr);
2784 if (IS_ERR(node)) {
2785 err = PTR_ERR(node);
2786 goto out;
2787 }
2788
2789 ret = relocate_tree_block(trans, rc, node, &block->key,
2790 path);
2791 if (ret < 0) {
2792 if (ret != -EAGAIN || rb_node == rb_first(blocks))
2793 err = ret;
2794 goto out;
2795 }
2796 rb_node = rb_next(rb_node);
2797 }
2798 out:
2799 free_block_list(blocks);
2800 err = finish_pending_nodes(trans, rc, path, err);
2801
2802 btrfs_free_path(path);
2803 return err;
2804 }
2805
2806 static noinline_for_stack
2807 int prealloc_file_extent_cluster(struct inode *inode,
2808 struct file_extent_cluster *cluster)
2809 {
2810 u64 alloc_hint = 0;
2811 u64 start;
2812 u64 end;
2813 u64 offset = BTRFS_I(inode)->index_cnt;
2814 u64 num_bytes;
2815 int nr = 0;
2816 int ret = 0;
2817
2818 BUG_ON(cluster->start != cluster->boundary[0]);
2819 mutex_lock(&inode->i_mutex);
2820
2821 ret = btrfs_check_data_free_space(inode, cluster->end +
2822 1 - cluster->start);
2823 if (ret)
2824 goto out;
2825
2826 while (nr < cluster->nr) {
2827 start = cluster->boundary[nr] - offset;
2828 if (nr + 1 < cluster->nr)
2829 end = cluster->boundary[nr + 1] - 1 - offset;
2830 else
2831 end = cluster->end - offset;
2832
2833 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2834 num_bytes = end + 1 - start;
2835 ret = btrfs_prealloc_file_range(inode, 0, start,
2836 num_bytes, num_bytes,
2837 end + 1, &alloc_hint);
2838 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2839 if (ret)
2840 break;
2841 nr++;
2842 }
2843 btrfs_free_reserved_data_space(inode, cluster->end +
2844 1 - cluster->start);
2845 out:
2846 mutex_unlock(&inode->i_mutex);
2847 return ret;
2848 }
2849
2850 static noinline_for_stack
2851 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
2852 u64 block_start)
2853 {
2854 struct btrfs_root *root = BTRFS_I(inode)->root;
2855 struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2856 struct extent_map *em;
2857 int ret = 0;
2858
2859 em = alloc_extent_map(GFP_NOFS);
2860 if (!em)
2861 return -ENOMEM;
2862
2863 em->start = start;
2864 em->len = end + 1 - start;
2865 em->block_len = em->len;
2866 em->block_start = block_start;
2867 em->bdev = root->fs_info->fs_devices->latest_bdev;
2868 set_bit(EXTENT_FLAG_PINNED, &em->flags);
2869
2870 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2871 while (1) {
2872 write_lock(&em_tree->lock);
2873 ret = add_extent_mapping(em_tree, em);
2874 write_unlock(&em_tree->lock);
2875 if (ret != -EEXIST) {
2876 free_extent_map(em);
2877 break;
2878 }
2879 btrfs_drop_extent_cache(inode, start, end, 0);
2880 }
2881 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2882 return ret;
2883 }
2884
2885 static int relocate_file_extent_cluster(struct inode *inode,
2886 struct file_extent_cluster *cluster)
2887 {
2888 u64 page_start;
2889 u64 page_end;
2890 u64 offset = BTRFS_I(inode)->index_cnt;
2891 unsigned long index;
2892 unsigned long last_index;
2893 struct page *page;
2894 struct file_ra_state *ra;
2895 int nr = 0;
2896 int ret = 0;
2897
2898 if (!cluster->nr)
2899 return 0;
2900
2901 ra = kzalloc(sizeof(*ra), GFP_NOFS);
2902 if (!ra)
2903 return -ENOMEM;
2904
2905 ret = prealloc_file_extent_cluster(inode, cluster);
2906 if (ret)
2907 goto out;
2908
2909 file_ra_state_init(ra, inode->i_mapping);
2910
2911 ret = setup_extent_mapping(inode, cluster->start - offset,
2912 cluster->end - offset, cluster->start);
2913 if (ret)
2914 goto out;
2915
2916 index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
2917 last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
2918 while (index <= last_index) {
2919 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
2920 if (ret)
2921 goto out;
2922
2923 page = find_lock_page(inode->i_mapping, index);
2924 if (!page) {
2925 page_cache_sync_readahead(inode->i_mapping,
2926 ra, NULL, index,
2927 last_index + 1 - index);
2928 page = grab_cache_page(inode->i_mapping, index);
2929 if (!page) {
2930 btrfs_delalloc_release_metadata(inode,
2931 PAGE_CACHE_SIZE);
2932 ret = -ENOMEM;
2933 goto out;
2934 }
2935 }
2936
2937 if (PageReadahead(page)) {
2938 page_cache_async_readahead(inode->i_mapping,
2939 ra, NULL, page, index,
2940 last_index + 1 - index);
2941 }
2942
2943 if (!PageUptodate(page)) {
2944 btrfs_readpage(NULL, page);
2945 lock_page(page);
2946 if (!PageUptodate(page)) {
2947 unlock_page(page);
2948 page_cache_release(page);
2949 btrfs_delalloc_release_metadata(inode,
2950 PAGE_CACHE_SIZE);
2951 ret = -EIO;
2952 goto out;
2953 }
2954 }
2955
2956 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2957 page_end = page_start + PAGE_CACHE_SIZE - 1;
2958
2959 lock_extent(&BTRFS_I(inode)->io_tree,
2960 page_start, page_end, GFP_NOFS);
2961
2962 set_page_extent_mapped(page);
2963
2964 if (nr < cluster->nr &&
2965 page_start + offset == cluster->boundary[nr]) {
2966 set_extent_bits(&BTRFS_I(inode)->io_tree,
2967 page_start, page_end,
2968 EXTENT_BOUNDARY, GFP_NOFS);
2969 nr++;
2970 }
2971
2972 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
2973 set_page_dirty(page);
2974
2975 unlock_extent(&BTRFS_I(inode)->io_tree,
2976 page_start, page_end, GFP_NOFS);
2977 unlock_page(page);
2978 page_cache_release(page);
2979
2980 index++;
2981 balance_dirty_pages_ratelimited(inode->i_mapping);
2982 btrfs_throttle(BTRFS_I(inode)->root);
2983 }
2984 WARN_ON(nr != cluster->nr);
2985 out:
2986 kfree(ra);
2987 return ret;
2988 }
2989
2990 static noinline_for_stack
2991 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
2992 struct file_extent_cluster *cluster)
2993 {
2994 int ret;
2995
2996 if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
2997 ret = relocate_file_extent_cluster(inode, cluster);
2998 if (ret)
2999 return ret;
3000 cluster->nr = 0;
3001 }
3002
3003 if (!cluster->nr)
3004 cluster->start = extent_key->objectid;
3005 else
3006 BUG_ON(cluster->nr >= MAX_EXTENTS);
3007 cluster->end = extent_key->objectid + extent_key->offset - 1;
3008 cluster->boundary[cluster->nr] = extent_key->objectid;
3009 cluster->nr++;
3010
3011 if (cluster->nr >= MAX_EXTENTS) {
3012 ret = relocate_file_extent_cluster(inode, cluster);
3013 if (ret)
3014 return ret;
3015 cluster->nr = 0;
3016 }
3017 return 0;
3018 }
3019
3020 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3021 static int get_ref_objectid_v0(struct reloc_control *rc,
3022 struct btrfs_path *path,
3023 struct btrfs_key *extent_key,
3024 u64 *ref_objectid, int *path_change)
3025 {
3026 struct btrfs_key key;
3027 struct extent_buffer *leaf;
3028 struct btrfs_extent_ref_v0 *ref0;
3029 int ret;
3030 int slot;
3031
3032 leaf = path->nodes[0];
3033 slot = path->slots[0];
3034 while (1) {
3035 if (slot >= btrfs_header_nritems(leaf)) {
3036 ret = btrfs_next_leaf(rc->extent_root, path);
3037 if (ret < 0)
3038 return ret;
3039 BUG_ON(ret > 0);
3040 leaf = path->nodes[0];
3041 slot = path->slots[0];
3042 if (path_change)
3043 *path_change = 1;
3044 }
3045 btrfs_item_key_to_cpu(leaf, &key, slot);
3046 if (key.objectid != extent_key->objectid)
3047 return -ENOENT;
3048
3049 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3050 slot++;
3051 continue;
3052 }
3053 ref0 = btrfs_item_ptr(leaf, slot,
3054 struct btrfs_extent_ref_v0);
3055 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3056 break;
3057 }
3058 return 0;
3059 }
3060 #endif
3061
3062 /*
3063 * helper to add a tree block to the list.
3064 * the major work is getting the generation and level of the block
3065 */
3066 static int add_tree_block(struct reloc_control *rc,
3067 struct btrfs_key *extent_key,
3068 struct btrfs_path *path,
3069 struct rb_root *blocks)
3070 {
3071 struct extent_buffer *eb;
3072 struct btrfs_extent_item *ei;
3073 struct btrfs_tree_block_info *bi;
3074 struct tree_block *block;
3075 struct rb_node *rb_node;
3076 u32 item_size;
3077 int level = -1;
3078 int generation;
3079
3080 eb = path->nodes[0];
3081 item_size = btrfs_item_size_nr(eb, path->slots[0]);
3082
3083 if (item_size >= sizeof(*ei) + sizeof(*bi)) {
3084 ei = btrfs_item_ptr(eb, path->slots[0],
3085 struct btrfs_extent_item);
3086 bi = (struct btrfs_tree_block_info *)(ei + 1);
3087 generation = btrfs_extent_generation(eb, ei);
3088 level = btrfs_tree_block_level(eb, bi);
3089 } else {
3090 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3091 u64 ref_owner;
3092 int ret;
3093
3094 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3095 ret = get_ref_objectid_v0(rc, path, extent_key,
3096 &ref_owner, NULL);
3097 if (ret < 0)
3098 return ret;
3099 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3100 level = (int)ref_owner;
3101 /* FIXME: get real generation */
3102 generation = 0;
3103 #else
3104 BUG();
3105 #endif
3106 }
3107
3108 btrfs_release_path(rc->extent_root, path);
3109
3110 BUG_ON(level == -1);
3111
3112 block = kmalloc(sizeof(*block), GFP_NOFS);
3113 if (!block)
3114 return -ENOMEM;
3115
3116 block->bytenr = extent_key->objectid;
3117 block->key.objectid = extent_key->offset;
3118 block->key.offset = generation;
3119 block->level = level;
3120 block->key_ready = 0;
3121
3122 rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3123 BUG_ON(rb_node);
3124
3125 return 0;
3126 }
3127
3128 /*
3129 * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3130 */
3131 static int __add_tree_block(struct reloc_control *rc,
3132 u64 bytenr, u32 blocksize,
3133 struct rb_root *blocks)
3134 {
3135 struct btrfs_path *path;
3136 struct btrfs_key key;
3137 int ret;
3138
3139 if (tree_block_processed(bytenr, blocksize, rc))
3140 return 0;
3141
3142 if (tree_search(blocks, bytenr))
3143 return 0;
3144
3145 path = btrfs_alloc_path();
3146 if (!path)
3147 return -ENOMEM;
3148
3149 key.objectid = bytenr;
3150 key.type = BTRFS_EXTENT_ITEM_KEY;
3151 key.offset = blocksize;
3152
3153 path->search_commit_root = 1;
3154 path->skip_locking = 1;
3155 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3156 if (ret < 0)
3157 goto out;
3158 BUG_ON(ret);
3159
3160 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3161 ret = add_tree_block(rc, &key, path, blocks);
3162 out:
3163 btrfs_free_path(path);
3164 return ret;
3165 }
3166
3167 /*
3168 * helper to check if the block use full backrefs for pointers in it
3169 */
3170 static int block_use_full_backref(struct reloc_control *rc,
3171 struct extent_buffer *eb)
3172 {
3173 u64 flags;
3174 int ret;
3175
3176 if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3177 btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3178 return 1;
3179
3180 ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3181 eb->start, eb->len, NULL, &flags);
3182 BUG_ON(ret);
3183
3184 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3185 ret = 1;
3186 else
3187 ret = 0;
3188 return ret;
3189 }
3190
3191 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3192 struct inode *inode, u64 ino)
3193 {
3194 struct btrfs_key key;
3195 struct btrfs_path *path;
3196 struct btrfs_root *root = fs_info->tree_root;
3197 struct btrfs_trans_handle *trans;
3198 unsigned long nr;
3199 int ret = 0;
3200
3201 if (inode)
3202 goto truncate;
3203
3204 key.objectid = ino;
3205 key.type = BTRFS_INODE_ITEM_KEY;
3206 key.offset = 0;
3207
3208 inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3209 if (!inode || IS_ERR(inode) || is_bad_inode(inode)) {
3210 if (inode && !IS_ERR(inode))
3211 iput(inode);
3212 return -ENOENT;
3213 }
3214
3215 truncate:
3216 path = btrfs_alloc_path();
3217 if (!path) {
3218 ret = -ENOMEM;
3219 goto out;
3220 }
3221
3222 trans = btrfs_join_transaction(root, 0);
3223 if (IS_ERR(trans)) {
3224 btrfs_free_path(path);
3225 goto out;
3226 }
3227
3228 ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
3229
3230 btrfs_free_path(path);
3231 nr = trans->blocks_used;
3232 btrfs_end_transaction(trans, root);
3233 btrfs_btree_balance_dirty(root, nr);
3234 out:
3235 iput(inode);
3236 return ret;
3237 }
3238
3239 /*
3240 * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3241 * this function scans fs tree to find blocks reference the data extent
3242 */
3243 static int find_data_references(struct reloc_control *rc,
3244 struct btrfs_key *extent_key,
3245 struct extent_buffer *leaf,
3246 struct btrfs_extent_data_ref *ref,
3247 struct rb_root *blocks)
3248 {
3249 struct btrfs_path *path;
3250 struct tree_block *block;
3251 struct btrfs_root *root;
3252 struct btrfs_file_extent_item *fi;
3253 struct rb_node *rb_node;
3254 struct btrfs_key key;
3255 u64 ref_root;
3256 u64 ref_objectid;
3257 u64 ref_offset;
3258 u32 ref_count;
3259 u32 nritems;
3260 int err = 0;
3261 int added = 0;
3262 int counted;
3263 int ret;
3264
3265 ref_root = btrfs_extent_data_ref_root(leaf, ref);
3266 ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3267 ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3268 ref_count = btrfs_extent_data_ref_count(leaf, ref);
3269
3270 /*
3271 * This is an extent belonging to the free space cache, lets just delete
3272 * it and redo the search.
3273 */
3274 if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3275 ret = delete_block_group_cache(rc->extent_root->fs_info,
3276 NULL, ref_objectid);
3277 if (ret != -ENOENT)
3278 return ret;
3279 ret = 0;
3280 }
3281
3282 path = btrfs_alloc_path();
3283 if (!path)
3284 return -ENOMEM;
3285
3286 root = read_fs_root(rc->extent_root->fs_info, ref_root);
3287 if (IS_ERR(root)) {
3288 err = PTR_ERR(root);
3289 goto out;
3290 }
3291
3292 key.objectid = ref_objectid;
3293 key.offset = ref_offset;
3294 key.type = BTRFS_EXTENT_DATA_KEY;
3295
3296 path->search_commit_root = 1;
3297 path->skip_locking = 1;
3298 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3299 if (ret < 0) {
3300 err = ret;
3301 goto out;
3302 }
3303
3304 leaf = path->nodes[0];
3305 nritems = btrfs_header_nritems(leaf);
3306 /*
3307 * the references in tree blocks that use full backrefs
3308 * are not counted in
3309 */
3310 if (block_use_full_backref(rc, leaf))
3311 counted = 0;
3312 else
3313 counted = 1;
3314 rb_node = tree_search(blocks, leaf->start);
3315 if (rb_node) {
3316 if (counted)
3317 added = 1;
3318 else
3319 path->slots[0] = nritems;
3320 }
3321
3322 while (ref_count > 0) {
3323 while (path->slots[0] >= nritems) {
3324 ret = btrfs_next_leaf(root, path);
3325 if (ret < 0) {
3326 err = ret;
3327 goto out;
3328 }
3329 if (ret > 0) {
3330 WARN_ON(1);
3331 goto out;
3332 }
3333
3334 leaf = path->nodes[0];
3335 nritems = btrfs_header_nritems(leaf);
3336 added = 0;
3337
3338 if (block_use_full_backref(rc, leaf))
3339 counted = 0;
3340 else
3341 counted = 1;
3342 rb_node = tree_search(blocks, leaf->start);
3343 if (rb_node) {
3344 if (counted)
3345 added = 1;
3346 else
3347 path->slots[0] = nritems;
3348 }
3349 }
3350
3351 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3352 if (key.objectid != ref_objectid ||
3353 key.type != BTRFS_EXTENT_DATA_KEY) {
3354 WARN_ON(1);
3355 break;
3356 }
3357
3358 fi = btrfs_item_ptr(leaf, path->slots[0],
3359 struct btrfs_file_extent_item);
3360
3361 if (btrfs_file_extent_type(leaf, fi) ==
3362 BTRFS_FILE_EXTENT_INLINE)
3363 goto next;
3364
3365 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3366 extent_key->objectid)
3367 goto next;
3368
3369 key.offset -= btrfs_file_extent_offset(leaf, fi);
3370 if (key.offset != ref_offset)
3371 goto next;
3372
3373 if (counted)
3374 ref_count--;
3375 if (added)
3376 goto next;
3377
3378 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3379 block = kmalloc(sizeof(*block), GFP_NOFS);
3380 if (!block) {
3381 err = -ENOMEM;
3382 break;
3383 }
3384 block->bytenr = leaf->start;
3385 btrfs_item_key_to_cpu(leaf, &block->key, 0);
3386 block->level = 0;
3387 block->key_ready = 1;
3388 rb_node = tree_insert(blocks, block->bytenr,
3389 &block->rb_node);
3390 BUG_ON(rb_node);
3391 }
3392 if (counted)
3393 added = 1;
3394 else
3395 path->slots[0] = nritems;
3396 next:
3397 path->slots[0]++;
3398
3399 }
3400 out:
3401 btrfs_free_path(path);
3402 return err;
3403 }
3404
3405 /*
3406 * hepler to find all tree blocks that reference a given data extent
3407 */
3408 static noinline_for_stack
3409 int add_data_references(struct reloc_control *rc,
3410 struct btrfs_key *extent_key,
3411 struct btrfs_path *path,
3412 struct rb_root *blocks)
3413 {
3414 struct btrfs_key key;
3415 struct extent_buffer *eb;
3416 struct btrfs_extent_data_ref *dref;
3417 struct btrfs_extent_inline_ref *iref;
3418 unsigned long ptr;
3419 unsigned long end;
3420 u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3421 int ret;
3422 int err = 0;
3423
3424 eb = path->nodes[0];
3425 ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3426 end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3427 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3428 if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3429 ptr = end;
3430 else
3431 #endif
3432 ptr += sizeof(struct btrfs_extent_item);
3433
3434 while (ptr < end) {
3435 iref = (struct btrfs_extent_inline_ref *)ptr;
3436 key.type = btrfs_extent_inline_ref_type(eb, iref);
3437 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3438 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3439 ret = __add_tree_block(rc, key.offset, blocksize,
3440 blocks);
3441 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3442 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3443 ret = find_data_references(rc, extent_key,
3444 eb, dref, blocks);
3445 } else {
3446 BUG();
3447 }
3448 ptr += btrfs_extent_inline_ref_size(key.type);
3449 }
3450 WARN_ON(ptr > end);
3451
3452 while (1) {
3453 cond_resched();
3454 eb = path->nodes[0];
3455 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3456 ret = btrfs_next_leaf(rc->extent_root, path);
3457 if (ret < 0) {
3458 err = ret;
3459 break;
3460 }
3461 if (ret > 0)
3462 break;
3463 eb = path->nodes[0];
3464 }
3465
3466 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3467 if (key.objectid != extent_key->objectid)
3468 break;
3469
3470 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3471 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3472 key.type == BTRFS_EXTENT_REF_V0_KEY) {
3473 #else
3474 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3475 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3476 #endif
3477 ret = __add_tree_block(rc, key.offset, blocksize,
3478 blocks);
3479 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3480 dref = btrfs_item_ptr(eb, path->slots[0],
3481 struct btrfs_extent_data_ref);
3482 ret = find_data_references(rc, extent_key,
3483 eb, dref, blocks);
3484 } else {
3485 ret = 0;
3486 }
3487 if (ret) {
3488 err = ret;
3489 break;
3490 }
3491 path->slots[0]++;
3492 }
3493 btrfs_release_path(rc->extent_root, path);
3494 if (err)
3495 free_block_list(blocks);
3496 return err;
3497 }
3498
3499 /*
3500 * hepler to find next unprocessed extent
3501 */
3502 static noinline_for_stack
3503 int find_next_extent(struct btrfs_trans_handle *trans,
3504 struct reloc_control *rc, struct btrfs_path *path,
3505 struct btrfs_key *extent_key)
3506 {
3507 struct btrfs_key key;
3508 struct extent_buffer *leaf;
3509 u64 start, end, last;
3510 int ret;
3511
3512 last = rc->block_group->key.objectid + rc->block_group->key.offset;
3513 while (1) {
3514 cond_resched();
3515 if (rc->search_start >= last) {
3516 ret = 1;
3517 break;
3518 }
3519
3520 key.objectid = rc->search_start;
3521 key.type = BTRFS_EXTENT_ITEM_KEY;
3522 key.offset = 0;
3523
3524 path->search_commit_root = 1;
3525 path->skip_locking = 1;
3526 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3527 0, 0);
3528 if (ret < 0)
3529 break;
3530 next:
3531 leaf = path->nodes[0];
3532 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3533 ret = btrfs_next_leaf(rc->extent_root, path);
3534 if (ret != 0)
3535 break;
3536 leaf = path->nodes[0];
3537 }
3538
3539 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3540 if (key.objectid >= last) {
3541 ret = 1;
3542 break;
3543 }
3544
3545 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3546 key.objectid + key.offset <= rc->search_start) {
3547 path->slots[0]++;
3548 goto next;
3549 }
3550
3551 ret = find_first_extent_bit(&rc->processed_blocks,
3552 key.objectid, &start, &end,
3553 EXTENT_DIRTY);
3554
3555 if (ret == 0 && start <= key.objectid) {
3556 btrfs_release_path(rc->extent_root, path);
3557 rc->search_start = end + 1;
3558 } else {
3559 rc->search_start = key.objectid + key.offset;
3560 memcpy(extent_key, &key, sizeof(key));
3561 return 0;
3562 }
3563 }
3564 btrfs_release_path(rc->extent_root, path);
3565 return ret;
3566 }
3567
3568 static void set_reloc_control(struct reloc_control *rc)
3569 {
3570 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3571 mutex_lock(&fs_info->trans_mutex);
3572 fs_info->reloc_ctl = rc;
3573 mutex_unlock(&fs_info->trans_mutex);
3574 }
3575
3576 static void unset_reloc_control(struct reloc_control *rc)
3577 {
3578 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3579 mutex_lock(&fs_info->trans_mutex);
3580 fs_info->reloc_ctl = NULL;
3581 mutex_unlock(&fs_info->trans_mutex);
3582 }
3583
3584 static int check_extent_flags(u64 flags)
3585 {
3586 if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3587 (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3588 return 1;
3589 if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3590 !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3591 return 1;
3592 if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3593 (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3594 return 1;
3595 return 0;
3596 }
3597
3598 static noinline_for_stack
3599 int prepare_to_relocate(struct reloc_control *rc)
3600 {
3601 struct btrfs_trans_handle *trans;
3602 int ret;
3603
3604 rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root);
3605 if (!rc->block_rsv)
3606 return -ENOMEM;
3607
3608 /*
3609 * reserve some space for creating reloc trees.
3610 * btrfs_init_reloc_root will use them when there
3611 * is no reservation in transaction handle.
3612 */
3613 ret = btrfs_block_rsv_add(NULL, rc->extent_root, rc->block_rsv,
3614 rc->extent_root->nodesize * 256);
3615 if (ret)
3616 return ret;
3617
3618 rc->block_rsv->refill_used = 1;
3619 btrfs_add_durable_block_rsv(rc->extent_root->fs_info, rc->block_rsv);
3620
3621 memset(&rc->cluster, 0, sizeof(rc->cluster));
3622 rc->search_start = rc->block_group->key.objectid;
3623 rc->extents_found = 0;
3624 rc->nodes_relocated = 0;
3625 rc->merging_rsv_size = 0;
3626
3627 rc->create_reloc_tree = 1;
3628 set_reloc_control(rc);
3629
3630 trans = btrfs_join_transaction(rc->extent_root, 1);
3631 btrfs_commit_transaction(trans, rc->extent_root);
3632 return 0;
3633 }
3634
3635 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3636 {
3637 struct rb_root blocks = RB_ROOT;
3638 struct btrfs_key key;
3639 struct btrfs_trans_handle *trans = NULL;
3640 struct btrfs_path *path;
3641 struct btrfs_extent_item *ei;
3642 unsigned long nr;
3643 u64 flags;
3644 u32 item_size;
3645 int ret;
3646 int err = 0;
3647
3648 path = btrfs_alloc_path();
3649 if (!path)
3650 return -ENOMEM;
3651
3652 ret = prepare_to_relocate(rc);
3653 if (ret) {
3654 err = ret;
3655 goto out_free;
3656 }
3657
3658 while (1) {
3659 trans = btrfs_start_transaction(rc->extent_root, 0);
3660
3661 if (update_backref_cache(trans, &rc->backref_cache)) {
3662 btrfs_end_transaction(trans, rc->extent_root);
3663 continue;
3664 }
3665
3666 ret = find_next_extent(trans, rc, path, &key);
3667 if (ret < 0)
3668 err = ret;
3669 if (ret != 0)
3670 break;
3671
3672 rc->extents_found++;
3673
3674 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3675 struct btrfs_extent_item);
3676 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3677 if (item_size >= sizeof(*ei)) {
3678 flags = btrfs_extent_flags(path->nodes[0], ei);
3679 ret = check_extent_flags(flags);
3680 BUG_ON(ret);
3681
3682 } else {
3683 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3684 u64 ref_owner;
3685 int path_change = 0;
3686
3687 BUG_ON(item_size !=
3688 sizeof(struct btrfs_extent_item_v0));
3689 ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3690 &path_change);
3691 if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3692 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3693 else
3694 flags = BTRFS_EXTENT_FLAG_DATA;
3695
3696 if (path_change) {
3697 btrfs_release_path(rc->extent_root, path);
3698
3699 path->search_commit_root = 1;
3700 path->skip_locking = 1;
3701 ret = btrfs_search_slot(NULL, rc->extent_root,
3702 &key, path, 0, 0);
3703 if (ret < 0) {
3704 err = ret;
3705 break;
3706 }
3707 BUG_ON(ret > 0);
3708 }
3709 #else
3710 BUG();
3711 #endif
3712 }
3713
3714 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3715 ret = add_tree_block(rc, &key, path, &blocks);
3716 } else if (rc->stage == UPDATE_DATA_PTRS &&
3717 (flags & BTRFS_EXTENT_FLAG_DATA)) {
3718 ret = add_data_references(rc, &key, path, &blocks);
3719 } else {
3720 btrfs_release_path(rc->extent_root, path);
3721 ret = 0;
3722 }
3723 if (ret < 0) {
3724 err = ret;
3725 break;
3726 }
3727
3728 if (!RB_EMPTY_ROOT(&blocks)) {
3729 ret = relocate_tree_blocks(trans, rc, &blocks);
3730 if (ret < 0) {
3731 if (ret != -EAGAIN) {
3732 err = ret;
3733 break;
3734 }
3735 rc->extents_found--;
3736 rc->search_start = key.objectid;
3737 }
3738 }
3739
3740 ret = btrfs_block_rsv_check(trans, rc->extent_root,
3741 rc->block_rsv, 0, 5);
3742 if (ret < 0) {
3743 if (ret != -EAGAIN) {
3744 err = ret;
3745 WARN_ON(1);
3746 break;
3747 }
3748 rc->commit_transaction = 1;
3749 }
3750
3751 if (rc->commit_transaction) {
3752 rc->commit_transaction = 0;
3753 ret = btrfs_commit_transaction(trans, rc->extent_root);
3754 BUG_ON(ret);
3755 } else {
3756 nr = trans->blocks_used;
3757 btrfs_end_transaction_throttle(trans, rc->extent_root);
3758 btrfs_btree_balance_dirty(rc->extent_root, nr);
3759 }
3760 trans = NULL;
3761
3762 if (rc->stage == MOVE_DATA_EXTENTS &&
3763 (flags & BTRFS_EXTENT_FLAG_DATA)) {
3764 rc->found_file_extent = 1;
3765 ret = relocate_data_extent(rc->data_inode,
3766 &key, &rc->cluster);
3767 if (ret < 0) {
3768 err = ret;
3769 break;
3770 }
3771 }
3772 }
3773
3774 btrfs_release_path(rc->extent_root, path);
3775 clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3776 GFP_NOFS);
3777
3778 if (trans) {
3779 nr = trans->blocks_used;
3780 btrfs_end_transaction_throttle(trans, rc->extent_root);
3781 btrfs_btree_balance_dirty(rc->extent_root, nr);
3782 }
3783
3784 if (!err) {
3785 ret = relocate_file_extent_cluster(rc->data_inode,
3786 &rc->cluster);
3787 if (ret < 0)
3788 err = ret;
3789 }
3790
3791 rc->create_reloc_tree = 0;
3792 set_reloc_control(rc);
3793
3794 backref_cache_cleanup(&rc->backref_cache);
3795 btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3796
3797 err = prepare_to_merge(rc, err);
3798
3799 merge_reloc_roots(rc);
3800
3801 rc->merge_reloc_tree = 0;
3802 unset_reloc_control(rc);
3803 btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3804
3805 /* get rid of pinned extents */
3806 trans = btrfs_join_transaction(rc->extent_root, 1);
3807 btrfs_commit_transaction(trans, rc->extent_root);
3808 out_free:
3809 btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
3810 btrfs_free_path(path);
3811 return err;
3812 }
3813
3814 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3815 struct btrfs_root *root, u64 objectid)
3816 {
3817 struct btrfs_path *path;
3818 struct btrfs_inode_item *item;
3819 struct extent_buffer *leaf;
3820 int ret;
3821
3822 path = btrfs_alloc_path();
3823 if (!path)
3824 return -ENOMEM;
3825
3826 ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3827 if (ret)
3828 goto out;
3829
3830 leaf = path->nodes[0];
3831 item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3832 memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3833 btrfs_set_inode_generation(leaf, item, 1);
3834 btrfs_set_inode_size(leaf, item, 0);
3835 btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3836 btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
3837 BTRFS_INODE_PREALLOC);
3838 btrfs_mark_buffer_dirty(leaf);
3839 btrfs_release_path(root, path);
3840 out:
3841 btrfs_free_path(path);
3842 return ret;
3843 }
3844
3845 /*
3846 * helper to create inode for data relocation.
3847 * the inode is in data relocation tree and its link count is 0
3848 */
3849 static noinline_for_stack
3850 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3851 struct btrfs_block_group_cache *group)
3852 {
3853 struct inode *inode = NULL;
3854 struct btrfs_trans_handle *trans;
3855 struct btrfs_root *root;
3856 struct btrfs_key key;
3857 unsigned long nr;
3858 u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3859 int err = 0;
3860
3861 root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3862 if (IS_ERR(root))
3863 return ERR_CAST(root);
3864
3865 trans = btrfs_start_transaction(root, 6);
3866 if (IS_ERR(trans))
3867 return ERR_CAST(trans);
3868
3869 err = btrfs_find_free_objectid(trans, root, objectid, &objectid);
3870 if (err)
3871 goto out;
3872
3873 err = __insert_orphan_inode(trans, root, objectid);
3874 BUG_ON(err);
3875
3876 key.objectid = objectid;
3877 key.type = BTRFS_INODE_ITEM_KEY;
3878 key.offset = 0;
3879 inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
3880 BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3881 BTRFS_I(inode)->index_cnt = group->key.objectid;
3882
3883 err = btrfs_orphan_add(trans, inode);
3884 out:
3885 nr = trans->blocks_used;
3886 btrfs_end_transaction(trans, root);
3887 btrfs_btree_balance_dirty(root, nr);
3888 if (err) {
3889 if (inode)
3890 iput(inode);
3891 inode = ERR_PTR(err);
3892 }
3893 return inode;
3894 }
3895
3896 static struct reloc_control *alloc_reloc_control(void)
3897 {
3898 struct reloc_control *rc;
3899
3900 rc = kzalloc(sizeof(*rc), GFP_NOFS);
3901 if (!rc)
3902 return NULL;
3903
3904 INIT_LIST_HEAD(&rc->reloc_roots);
3905 backref_cache_init(&rc->backref_cache);
3906 mapping_tree_init(&rc->reloc_root_tree);
3907 extent_io_tree_init(&rc->processed_blocks, NULL, GFP_NOFS);
3908 return rc;
3909 }
3910
3911 /*
3912 * function to relocate all extents in a block group.
3913 */
3914 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
3915 {
3916 struct btrfs_fs_info *fs_info = extent_root->fs_info;
3917 struct reloc_control *rc;
3918 struct inode *inode;
3919 struct btrfs_path *path;
3920 int ret;
3921 int rw = 0;
3922 int err = 0;
3923
3924 rc = alloc_reloc_control();
3925 if (!rc)
3926 return -ENOMEM;
3927
3928 rc->extent_root = extent_root;
3929
3930 rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
3931 BUG_ON(!rc->block_group);
3932
3933 if (!rc->block_group->ro) {
3934 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
3935 if (ret) {
3936 err = ret;
3937 goto out;
3938 }
3939 rw = 1;
3940 }
3941
3942 path = btrfs_alloc_path();
3943 if (!path) {
3944 err = -ENOMEM;
3945 goto out;
3946 }
3947
3948 inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
3949 path);
3950 btrfs_free_path(path);
3951
3952 if (!IS_ERR(inode))
3953 ret = delete_block_group_cache(fs_info, inode, 0);
3954 else
3955 ret = PTR_ERR(inode);
3956
3957 if (ret && ret != -ENOENT) {
3958 err = ret;
3959 goto out;
3960 }
3961
3962 rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
3963 if (IS_ERR(rc->data_inode)) {
3964 err = PTR_ERR(rc->data_inode);
3965 rc->data_inode = NULL;
3966 goto out;
3967 }
3968
3969 printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
3970 (unsigned long long)rc->block_group->key.objectid,
3971 (unsigned long long)rc->block_group->flags);
3972
3973 btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
3974 btrfs_wait_ordered_extents(fs_info->tree_root, 0, 0);
3975
3976 while (1) {
3977 mutex_lock(&fs_info->cleaner_mutex);
3978
3979 btrfs_clean_old_snapshots(fs_info->tree_root);
3980 ret = relocate_block_group(rc);
3981
3982 mutex_unlock(&fs_info->cleaner_mutex);
3983 if (ret < 0) {
3984 err = ret;
3985 goto out;
3986 }
3987
3988 if (rc->extents_found == 0)
3989 break;
3990
3991 printk(KERN_INFO "btrfs: found %llu extents\n",
3992 (unsigned long long)rc->extents_found);
3993
3994 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
3995 btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
3996 invalidate_mapping_pages(rc->data_inode->i_mapping,
3997 0, -1);
3998 rc->stage = UPDATE_DATA_PTRS;
3999 }
4000 }
4001
4002 filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4003 rc->block_group->key.objectid,
4004 rc->block_group->key.objectid +
4005 rc->block_group->key.offset - 1);
4006
4007 WARN_ON(rc->block_group->pinned > 0);
4008 WARN_ON(rc->block_group->reserved > 0);
4009 WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4010 out:
4011 if (err && rw)
4012 btrfs_set_block_group_rw(extent_root, rc->block_group);
4013 iput(rc->data_inode);
4014 btrfs_put_block_group(rc->block_group);
4015 kfree(rc);
4016 return err;
4017 }
4018
4019 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4020 {
4021 struct btrfs_trans_handle *trans;
4022 int ret;
4023
4024 trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4025
4026 memset(&root->root_item.drop_progress, 0,
4027 sizeof(root->root_item.drop_progress));
4028 root->root_item.drop_level = 0;
4029 btrfs_set_root_refs(&root->root_item, 0);
4030 ret = btrfs_update_root(trans, root->fs_info->tree_root,
4031 &root->root_key, &root->root_item);
4032 BUG_ON(ret);
4033
4034 ret = btrfs_end_transaction(trans, root->fs_info->tree_root);
4035 BUG_ON(ret);
4036 return 0;
4037 }
4038
4039 /*
4040 * recover relocation interrupted by system crash.
4041 *
4042 * this function resumes merging reloc trees with corresponding fs trees.
4043 * this is important for keeping the sharing of tree blocks
4044 */
4045 int btrfs_recover_relocation(struct btrfs_root *root)
4046 {
4047 LIST_HEAD(reloc_roots);
4048 struct btrfs_key key;
4049 struct btrfs_root *fs_root;
4050 struct btrfs_root *reloc_root;
4051 struct btrfs_path *path;
4052 struct extent_buffer *leaf;
4053 struct reloc_control *rc = NULL;
4054 struct btrfs_trans_handle *trans;
4055 int ret;
4056 int err = 0;
4057
4058 path = btrfs_alloc_path();
4059 if (!path)
4060 return -ENOMEM;
4061
4062 key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4063 key.type = BTRFS_ROOT_ITEM_KEY;
4064 key.offset = (u64)-1;
4065
4066 while (1) {
4067 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4068 path, 0, 0);
4069 if (ret < 0) {
4070 err = ret;
4071 goto out;
4072 }
4073 if (ret > 0) {
4074 if (path->slots[0] == 0)
4075 break;
4076 path->slots[0]--;
4077 }
4078 leaf = path->nodes[0];
4079 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4080 btrfs_release_path(root->fs_info->tree_root, path);
4081
4082 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4083 key.type != BTRFS_ROOT_ITEM_KEY)
4084 break;
4085
4086 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
4087 if (IS_ERR(reloc_root)) {
4088 err = PTR_ERR(reloc_root);
4089 goto out;
4090 }
4091
4092 list_add(&reloc_root->root_list, &reloc_roots);
4093
4094 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4095 fs_root = read_fs_root(root->fs_info,
4096 reloc_root->root_key.offset);
4097 if (IS_ERR(fs_root)) {
4098 ret = PTR_ERR(fs_root);
4099 if (ret != -ENOENT) {
4100 err = ret;
4101 goto out;
4102 }
4103 mark_garbage_root(reloc_root);
4104 }
4105 }
4106
4107 if (key.offset == 0)
4108 break;
4109
4110 key.offset--;
4111 }
4112 btrfs_release_path(root->fs_info->tree_root, path);
4113
4114 if (list_empty(&reloc_roots))
4115 goto out;
4116
4117 rc = alloc_reloc_control();
4118 if (!rc) {
4119 err = -ENOMEM;
4120 goto out;
4121 }
4122
4123 rc->extent_root = root->fs_info->extent_root;
4124
4125 set_reloc_control(rc);
4126
4127 trans = btrfs_join_transaction(rc->extent_root, 1);
4128
4129 rc->merge_reloc_tree = 1;
4130
4131 while (!list_empty(&reloc_roots)) {
4132 reloc_root = list_entry(reloc_roots.next,
4133 struct btrfs_root, root_list);
4134 list_del(&reloc_root->root_list);
4135
4136 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4137 list_add_tail(&reloc_root->root_list,
4138 &rc->reloc_roots);
4139 continue;
4140 }
4141
4142 fs_root = read_fs_root(root->fs_info,
4143 reloc_root->root_key.offset);
4144 BUG_ON(IS_ERR(fs_root));
4145
4146 __add_reloc_root(reloc_root);
4147 fs_root->reloc_root = reloc_root;
4148 }
4149
4150 btrfs_commit_transaction(trans, rc->extent_root);
4151
4152 merge_reloc_roots(rc);
4153
4154 unset_reloc_control(rc);
4155
4156 trans = btrfs_join_transaction(rc->extent_root, 1);
4157 btrfs_commit_transaction(trans, rc->extent_root);
4158 out:
4159 kfree(rc);
4160 while (!list_empty(&reloc_roots)) {
4161 reloc_root = list_entry(reloc_roots.next,
4162 struct btrfs_root, root_list);
4163 list_del(&reloc_root->root_list);
4164 free_extent_buffer(reloc_root->node);
4165 free_extent_buffer(reloc_root->commit_root);
4166 kfree(reloc_root);
4167 }
4168 btrfs_free_path(path);
4169
4170 if (err == 0) {
4171 /* cleanup orphan inode in data relocation tree */
4172 fs_root = read_fs_root(root->fs_info,
4173 BTRFS_DATA_RELOC_TREE_OBJECTID);
4174 if (IS_ERR(fs_root))
4175 err = PTR_ERR(fs_root);
4176 else
4177 btrfs_orphan_cleanup(fs_root);
4178 }
4179 return err;
4180 }
4181
4182 /*
4183 * helper to add ordered checksum for data relocation.
4184 *
4185 * cloning checksum properly handles the nodatasum extents.
4186 * it also saves CPU time to re-calculate the checksum.
4187 */
4188 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4189 {
4190 struct btrfs_ordered_sum *sums;
4191 struct btrfs_sector_sum *sector_sum;
4192 struct btrfs_ordered_extent *ordered;
4193 struct btrfs_root *root = BTRFS_I(inode)->root;
4194 size_t offset;
4195 int ret;
4196 u64 disk_bytenr;
4197 LIST_HEAD(list);
4198
4199 ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4200 BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4201
4202 disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4203 ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4204 disk_bytenr + len - 1, &list);
4205
4206 while (!list_empty(&list)) {
4207 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4208 list_del_init(&sums->list);
4209
4210 sector_sum = sums->sums;
4211 sums->bytenr = ordered->start;
4212
4213 offset = 0;
4214 while (offset < sums->len) {
4215 sector_sum->bytenr += ordered->start - disk_bytenr;
4216 sector_sum++;
4217 offset += root->sectorsize;
4218 }
4219
4220 btrfs_add_ordered_sum(inode, ordered, sums);
4221 }
4222 btrfs_put_ordered_extent(ordered);
4223 return ret;
4224 }
4225
4226 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4227 struct btrfs_root *root, struct extent_buffer *buf,
4228 struct extent_buffer *cow)
4229 {
4230 struct reloc_control *rc;
4231 struct backref_node *node;
4232 int first_cow = 0;
4233 int level;
4234 int ret;
4235
4236 rc = root->fs_info->reloc_ctl;
4237 if (!rc)
4238 return;
4239
4240 BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4241 root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4242
4243 level = btrfs_header_level(buf);
4244 if (btrfs_header_generation(buf) <=
4245 btrfs_root_last_snapshot(&root->root_item))
4246 first_cow = 1;
4247
4248 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4249 rc->create_reloc_tree) {
4250 WARN_ON(!first_cow && level == 0);
4251
4252 node = rc->backref_cache.path[level];
4253 BUG_ON(node->bytenr != buf->start &&
4254 node->new_bytenr != buf->start);
4255
4256 drop_node_buffer(node);
4257 extent_buffer_get(cow);
4258 node->eb = cow;
4259 node->new_bytenr = cow->start;
4260
4261 if (!node->pending) {
4262 list_move_tail(&node->list,
4263 &rc->backref_cache.pending[level]);
4264 node->pending = 1;
4265 }
4266
4267 if (first_cow)
4268 __mark_block_processed(rc, node);
4269
4270 if (first_cow && level > 0)
4271 rc->nodes_relocated += buf->len;
4272 }
4273
4274 if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4275 ret = replace_file_extents(trans, rc, root, cow);
4276 BUG_ON(ret);
4277 }
4278 }
4279
4280 /*
4281 * called before creating snapshot. it calculates metadata reservation
4282 * requried for relocating tree blocks in the snapshot
4283 */
4284 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4285 struct btrfs_pending_snapshot *pending,
4286 u64 *bytes_to_reserve)
4287 {
4288 struct btrfs_root *root;
4289 struct reloc_control *rc;
4290
4291 root = pending->root;
4292 if (!root->reloc_root)
4293 return;
4294
4295 rc = root->fs_info->reloc_ctl;
4296 if (!rc->merge_reloc_tree)
4297 return;
4298
4299 root = root->reloc_root;
4300 BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4301 /*
4302 * relocation is in the stage of merging trees. the space
4303 * used by merging a reloc tree is twice the size of
4304 * relocated tree nodes in the worst case. half for cowing
4305 * the reloc tree, half for cowing the fs tree. the space
4306 * used by cowing the reloc tree will be freed after the
4307 * tree is dropped. if we create snapshot, cowing the fs
4308 * tree may use more space than it frees. so we need
4309 * reserve extra space.
4310 */
4311 *bytes_to_reserve += rc->nodes_relocated;
4312 }
4313
4314 /*
4315 * called after snapshot is created. migrate block reservation
4316 * and create reloc root for the newly created snapshot
4317 */
4318 void btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4319 struct btrfs_pending_snapshot *pending)
4320 {
4321 struct btrfs_root *root = pending->root;
4322 struct btrfs_root *reloc_root;
4323 struct btrfs_root *new_root;
4324 struct reloc_control *rc;
4325 int ret;
4326
4327 if (!root->reloc_root)
4328 return;
4329
4330 rc = root->fs_info->reloc_ctl;
4331 rc->merging_rsv_size += rc->nodes_relocated;
4332
4333 if (rc->merge_reloc_tree) {
4334 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4335 rc->block_rsv,
4336 rc->nodes_relocated);
4337 BUG_ON(ret);
4338 }
4339
4340 new_root = pending->snap;
4341 reloc_root = create_reloc_root(trans, root->reloc_root,
4342 new_root->root_key.objectid);
4343
4344 __add_reloc_root(reloc_root);
4345 new_root->reloc_root = reloc_root;
4346
4347 if (rc->create_reloc_tree) {
4348 ret = clone_backref_node(trans, rc, root, reloc_root);
4349 BUG_ON(ret);
4350 }
4351 }