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Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad...
[zen-stable.git] / fs / btrfs / relocation.c
blobdff29d5e151a3b80d516be44cc1ebdf0d00adad6
1 /*
2 * Copyright (C) 2009 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/sched.h>
20 #include <linux/pagemap.h>
21 #include <linux/writeback.h>
22 #include <linux/blkdev.h>
23 #include <linux/rbtree.h>
24 #include <linux/slab.h>
25 #include "ctree.h"
26 #include "disk-io.h"
27 #include "transaction.h"
28 #include "volumes.h"
29 #include "locking.h"
30 #include "btrfs_inode.h"
31 #include "async-thread.h"
32 #include "free-space-cache.h"
33 #include "inode-map.h"
34
35 /*
36 * backref_node, mapping_node and tree_block start with this
37 */
38 struct tree_entry {
39 struct rb_node rb_node;
40 u64 bytenr;
41 };
42
43 /*
44 * present a tree block in the backref cache
45 */
46 struct backref_node {
47 struct rb_node rb_node;
48 u64 bytenr;
49
50 u64 new_bytenr;
51 /* objectid of tree block owner, can be not uptodate */
52 u64 owner;
53 /* link to pending, changed or detached list */
54 struct list_head list;
55 /* list of upper level blocks reference this block */
56 struct list_head upper;
57 /* list of child blocks in the cache */
58 struct list_head lower;
59 /* NULL if this node is not tree root */
60 struct btrfs_root *root;
61 /* extent buffer got by COW the block */
62 struct extent_buffer *eb;
63 /* level of tree block */
64 unsigned int level:8;
65 /* is the block in non-reference counted tree */
66 unsigned int cowonly:1;
67 /* 1 if no child node in the cache */
68 unsigned int lowest:1;
69 /* is the extent buffer locked */
70 unsigned int locked:1;
71 /* has the block been processed */
72 unsigned int processed:1;
73 /* have backrefs of this block been checked */
74 unsigned int checked:1;
75 /*
76 * 1 if corresponding block has been cowed but some upper
77 * level block pointers may not point to the new location
78 */
79 unsigned int pending:1;
80 /*
81 * 1 if the backref node isn't connected to any other
82 * backref node.
83 */
84 unsigned int detached:1;
85 };
86
87 /*
88 * present a block pointer in the backref cache
89 */
90 struct backref_edge {
91 struct list_head list[2];
92 struct backref_node *node[2];
93 };
94
95 #define LOWER 0
96 #define UPPER 1
97
98 struct backref_cache {
99 /* red black tree of all backref nodes in the cache */
100 struct rb_root rb_root;
101 /* for passing backref nodes to btrfs_reloc_cow_block */
102 struct backref_node *path[BTRFS_MAX_LEVEL];
103 /*
104 * list of blocks that have been cowed but some block
105 * pointers in upper level blocks may not reflect the
106 * new location
107 */
108 struct list_head pending[BTRFS_MAX_LEVEL];
109 /* list of backref nodes with no child node */
110 struct list_head leaves;
111 /* list of blocks that have been cowed in current transaction */
112 struct list_head changed;
113 /* list of detached backref node. */
114 struct list_head detached;
115
116 u64 last_trans;
117
118 int nr_nodes;
119 int nr_edges;
120 };
121
122 /*
123 * map address of tree root to tree
124 */
125 struct mapping_node {
126 struct rb_node rb_node;
127 u64 bytenr;
128 void *data;
129 };
130
131 struct mapping_tree {
132 struct rb_root rb_root;
133 spinlock_t lock;
134 };
135
136 /*
137 * present a tree block to process
138 */
139 struct tree_block {
140 struct rb_node rb_node;
141 u64 bytenr;
142 struct btrfs_key key;
143 unsigned int level:8;
144 unsigned int key_ready:1;
145 };
146
147 #define MAX_EXTENTS 128
148
149 struct file_extent_cluster {
150 u64 start;
151 u64 end;
152 u64 boundary[MAX_EXTENTS];
153 unsigned int nr;
154 };
155
156 struct reloc_control {
157 /* block group to relocate */
158 struct btrfs_block_group_cache *block_group;
159 /* extent tree */
160 struct btrfs_root *extent_root;
161 /* inode for moving data */
162 struct inode *data_inode;
163
164 struct btrfs_block_rsv *block_rsv;
165
166 struct backref_cache backref_cache;
167
168 struct file_extent_cluster cluster;
169 /* tree blocks have been processed */
170 struct extent_io_tree processed_blocks;
171 /* map start of tree root to corresponding reloc tree */
172 struct mapping_tree reloc_root_tree;
173 /* list of reloc trees */
174 struct list_head reloc_roots;
175 /* size of metadata reservation for merging reloc trees */
176 u64 merging_rsv_size;
177 /* size of relocated tree nodes */
178 u64 nodes_relocated;
179
180 u64 search_start;
181 u64 extents_found;
182
183 unsigned int stage:8;
184 unsigned int create_reloc_tree:1;
185 unsigned int merge_reloc_tree:1;
186 unsigned int found_file_extent:1;
187 unsigned int commit_transaction:1;
188 };
189
190 /* stages of data relocation */
191 #define MOVE_DATA_EXTENTS 0
192 #define UPDATE_DATA_PTRS 1
193
194 static void remove_backref_node(struct backref_cache *cache,
195 struct backref_node *node);
196 static void __mark_block_processed(struct reloc_control *rc,
197 struct backref_node *node);
198
199 static void mapping_tree_init(struct mapping_tree *tree)
200 {
201 tree->rb_root = RB_ROOT;
202 spin_lock_init(&tree->lock);
203 }
204
205 static void backref_cache_init(struct backref_cache *cache)
206 {
207 int i;
208 cache->rb_root = RB_ROOT;
209 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
210 INIT_LIST_HEAD(&cache->pending[i]);
211 INIT_LIST_HEAD(&cache->changed);
212 INIT_LIST_HEAD(&cache->detached);
213 INIT_LIST_HEAD(&cache->leaves);
214 }
215
216 static void backref_cache_cleanup(struct backref_cache *cache)
217 {
218 struct backref_node *node;
219 int i;
220
221 while (!list_empty(&cache->detached)) {
222 node = list_entry(cache->detached.next,
223 struct backref_node, list);
224 remove_backref_node(cache, node);
225 }
226
227 while (!list_empty(&cache->leaves)) {
228 node = list_entry(cache->leaves.next,
229 struct backref_node, lower);
230 remove_backref_node(cache, node);
231 }
232
233 cache->last_trans = 0;
234
235 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
236 BUG_ON(!list_empty(&cache->pending[i]));
237 BUG_ON(!list_empty(&cache->changed));
238 BUG_ON(!list_empty(&cache->detached));
239 BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
240 BUG_ON(cache->nr_nodes);
241 BUG_ON(cache->nr_edges);
242 }
243
244 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
245 {
246 struct backref_node *node;
247
248 node = kzalloc(sizeof(*node), GFP_NOFS);
249 if (node) {
250 INIT_LIST_HEAD(&node->list);
251 INIT_LIST_HEAD(&node->upper);
252 INIT_LIST_HEAD(&node->lower);
253 RB_CLEAR_NODE(&node->rb_node);
254 cache->nr_nodes++;
255 }
256 return node;
257 }
258
259 static void free_backref_node(struct backref_cache *cache,
260 struct backref_node *node)
261 {
262 if (node) {
263 cache->nr_nodes--;
264 kfree(node);
265 }
266 }
267
268 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
269 {
270 struct backref_edge *edge;
271
272 edge = kzalloc(sizeof(*edge), GFP_NOFS);
273 if (edge)
274 cache->nr_edges++;
275 return edge;
276 }
277
278 static void free_backref_edge(struct backref_cache *cache,
279 struct backref_edge *edge)
280 {
281 if (edge) {
282 cache->nr_edges--;
283 kfree(edge);
284 }
285 }
286
287 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
288 struct rb_node *node)
289 {
290 struct rb_node **p = &root->rb_node;
291 struct rb_node *parent = NULL;
292 struct tree_entry *entry;
293
294 while (*p) {
295 parent = *p;
296 entry = rb_entry(parent, struct tree_entry, rb_node);
297
298 if (bytenr < entry->bytenr)
299 p = &(*p)->rb_left;
300 else if (bytenr > entry->bytenr)
301 p = &(*p)->rb_right;
302 else
303 return parent;
304 }
305
306 rb_link_node(node, parent, p);
307 rb_insert_color(node, root);
308 return NULL;
309 }
310
311 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
312 {
313 struct rb_node *n = root->rb_node;
314 struct tree_entry *entry;
315
316 while (n) {
317 entry = rb_entry(n, struct tree_entry, rb_node);
318
319 if (bytenr < entry->bytenr)
320 n = n->rb_left;
321 else if (bytenr > entry->bytenr)
322 n = n->rb_right;
323 else
324 return n;
325 }
326 return NULL;
327 }
328
329 /*
330 * walk up backref nodes until reach node presents tree root
331 */
332 static struct backref_node *walk_up_backref(struct backref_node *node,
333 struct backref_edge *edges[],
334 int *index)
335 {
336 struct backref_edge *edge;
337 int idx = *index;
338
339 while (!list_empty(&node->upper)) {
340 edge = list_entry(node->upper.next,
341 struct backref_edge, list[LOWER]);
342 edges[idx++] = edge;
343 node = edge->node[UPPER];
344 }
345 BUG_ON(node->detached);
346 *index = idx;
347 return node;
348 }
349
350 /*
351 * walk down backref nodes to find start of next reference path
352 */
353 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
354 int *index)
355 {
356 struct backref_edge *edge;
357 struct backref_node *lower;
358 int idx = *index;
359
360 while (idx > 0) {
361 edge = edges[idx - 1];
362 lower = edge->node[LOWER];
363 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
364 idx--;
365 continue;
366 }
367 edge = list_entry(edge->list[LOWER].next,
368 struct backref_edge, list[LOWER]);
369 edges[idx - 1] = edge;
370 *index = idx;
371 return edge->node[UPPER];
372 }
373 *index = 0;
374 return NULL;
375 }
376
377 static void unlock_node_buffer(struct backref_node *node)
378 {
379 if (node->locked) {
380 btrfs_tree_unlock(node->eb);
381 node->locked = 0;
382 }
383 }
384
385 static void drop_node_buffer(struct backref_node *node)
386 {
387 if (node->eb) {
388 unlock_node_buffer(node);
389 free_extent_buffer(node->eb);
390 node->eb = NULL;
391 }
392 }
393
394 static void drop_backref_node(struct backref_cache *tree,
395 struct backref_node *node)
396 {
397 BUG_ON(!list_empty(&node->upper));
398
399 drop_node_buffer(node);
400 list_del(&node->list);
401 list_del(&node->lower);
402 if (!RB_EMPTY_NODE(&node->rb_node))
403 rb_erase(&node->rb_node, &tree->rb_root);
404 free_backref_node(tree, node);
405 }
406
407 /*
408 * remove a backref node from the backref cache
409 */
410 static void remove_backref_node(struct backref_cache *cache,
411 struct backref_node *node)
412 {
413 struct backref_node *upper;
414 struct backref_edge *edge;
415
416 if (!node)
417 return;
418
419 BUG_ON(!node->lowest && !node->detached);
420 while (!list_empty(&node->upper)) {
421 edge = list_entry(node->upper.next, struct backref_edge,
422 list[LOWER]);
423 upper = edge->node[UPPER];
424 list_del(&edge->list[LOWER]);
425 list_del(&edge->list[UPPER]);
426 free_backref_edge(cache, edge);
427
428 if (RB_EMPTY_NODE(&upper->rb_node)) {
429 BUG_ON(!list_empty(&node->upper));
430 drop_backref_node(cache, node);
431 node = upper;
432 node->lowest = 1;
433 continue;
434 }
435 /*
436 * add the node to leaf node list if no other
437 * child block cached.
438 */
439 if (list_empty(&upper->lower)) {
440 list_add_tail(&upper->lower, &cache->leaves);
441 upper->lowest = 1;
442 }
443 }
444
445 drop_backref_node(cache, node);
446 }
447
448 static void update_backref_node(struct backref_cache *cache,
449 struct backref_node *node, u64 bytenr)
450 {
451 struct rb_node *rb_node;
452 rb_erase(&node->rb_node, &cache->rb_root);
453 node->bytenr = bytenr;
454 rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
455 BUG_ON(rb_node);
456 }
457
458 /*
459 * update backref cache after a transaction commit
460 */
461 static int update_backref_cache(struct btrfs_trans_handle *trans,
462 struct backref_cache *cache)
463 {
464 struct backref_node *node;
465 int level = 0;
466
467 if (cache->last_trans == 0) {
468 cache->last_trans = trans->transid;
469 return 0;
470 }
471
472 if (cache->last_trans == trans->transid)
473 return 0;
474
475 /*
476 * detached nodes are used to avoid unnecessary backref
477 * lookup. transaction commit changes the extent tree.
478 * so the detached nodes are no longer useful.
479 */
480 while (!list_empty(&cache->detached)) {
481 node = list_entry(cache->detached.next,
482 struct backref_node, list);
483 remove_backref_node(cache, node);
484 }
485
486 while (!list_empty(&cache->changed)) {
487 node = list_entry(cache->changed.next,
488 struct backref_node, list);
489 list_del_init(&node->list);
490 BUG_ON(node->pending);
491 update_backref_node(cache, node, node->new_bytenr);
492 }
493
494 /*
495 * some nodes can be left in the pending list if there were
496 * errors during processing the pending nodes.
497 */
498 for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
499 list_for_each_entry(node, &cache->pending[level], list) {
500 BUG_ON(!node->pending);
501 if (node->bytenr == node->new_bytenr)
502 continue;
503 update_backref_node(cache, node, node->new_bytenr);
504 }
505 }
506
507 cache->last_trans = 0;
508 return 1;
509 }
510
511
512 static int should_ignore_root(struct btrfs_root *root)
513 {
514 struct btrfs_root *reloc_root;
515
516 if (!root->ref_cows)
517 return 0;
518
519 reloc_root = root->reloc_root;
520 if (!reloc_root)
521 return 0;
522
523 if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
524 root->fs_info->running_transaction->transid - 1)
525 return 0;
526 /*
527 * if there is reloc tree and it was created in previous
528 * transaction backref lookup can find the reloc tree,
529 * so backref node for the fs tree root is useless for
530 * relocation.
531 */
532 return 1;
533 }
534 /*
535 * find reloc tree by address of tree root
536 */
537 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
538 u64 bytenr)
539 {
540 struct rb_node *rb_node;
541 struct mapping_node *node;
542 struct btrfs_root *root = NULL;
543
544 spin_lock(&rc->reloc_root_tree.lock);
545 rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
546 if (rb_node) {
547 node = rb_entry(rb_node, struct mapping_node, rb_node);
548 root = (struct btrfs_root *)node->data;
549 }
550 spin_unlock(&rc->reloc_root_tree.lock);
551 return root;
552 }
553
554 static int is_cowonly_root(u64 root_objectid)
555 {
556 if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
557 root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
558 root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
559 root_objectid == BTRFS_DEV_TREE_OBJECTID ||
560 root_objectid == BTRFS_TREE_LOG_OBJECTID ||
561 root_objectid == BTRFS_CSUM_TREE_OBJECTID)
562 return 1;
563 return 0;
564 }
565
566 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
567 u64 root_objectid)
568 {
569 struct btrfs_key key;
570
571 key.objectid = root_objectid;
572 key.type = BTRFS_ROOT_ITEM_KEY;
573 if (is_cowonly_root(root_objectid))
574 key.offset = 0;
575 else
576 key.offset = (u64)-1;
577
578 return btrfs_read_fs_root_no_name(fs_info, &key);
579 }
580
581 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
582 static noinline_for_stack
583 struct btrfs_root *find_tree_root(struct reloc_control *rc,
584 struct extent_buffer *leaf,
585 struct btrfs_extent_ref_v0 *ref0)
586 {
587 struct btrfs_root *root;
588 u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
589 u64 generation = btrfs_ref_generation_v0(leaf, ref0);
590
591 BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
592
593 root = read_fs_root(rc->extent_root->fs_info, root_objectid);
594 BUG_ON(IS_ERR(root));
595
596 if (root->ref_cows &&
597 generation != btrfs_root_generation(&root->root_item))
598 return NULL;
599
600 return root;
601 }
602 #endif
603
604 static noinline_for_stack
605 int find_inline_backref(struct extent_buffer *leaf, int slot,
606 unsigned long *ptr, unsigned long *end)
607 {
608 struct btrfs_extent_item *ei;
609 struct btrfs_tree_block_info *bi;
610 u32 item_size;
611
612 item_size = btrfs_item_size_nr(leaf, slot);
613 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
614 if (item_size < sizeof(*ei)) {
615 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
616 return 1;
617 }
618 #endif
619 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
620 WARN_ON(!(btrfs_extent_flags(leaf, ei) &
621 BTRFS_EXTENT_FLAG_TREE_BLOCK));
622
623 if (item_size <= sizeof(*ei) + sizeof(*bi)) {
624 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
625 return 1;
626 }
627
628 bi = (struct btrfs_tree_block_info *)(ei + 1);
629 *ptr = (unsigned long)(bi + 1);
630 *end = (unsigned long)ei + item_size;
631 return 0;
632 }
633
634 /*
635 * build backref tree for a given tree block. root of the backref tree
636 * corresponds the tree block, leaves of the backref tree correspond
637 * roots of b-trees that reference the tree block.
638 *
639 * the basic idea of this function is check backrefs of a given block
640 * to find upper level blocks that refernece the block, and then check
641 * bakcrefs of these upper level blocks recursively. the recursion stop
642 * when tree root is reached or backrefs for the block is cached.
643 *
644 * NOTE: if we find backrefs for a block are cached, we know backrefs
645 * for all upper level blocks that directly/indirectly reference the
646 * block are also cached.
647 */
648 static noinline_for_stack
649 struct backref_node *build_backref_tree(struct reloc_control *rc,
650 struct btrfs_key *node_key,
651 int level, u64 bytenr)
652 {
653 struct backref_cache *cache = &rc->backref_cache;
654 struct btrfs_path *path1;
655 struct btrfs_path *path2;
656 struct extent_buffer *eb;
657 struct btrfs_root *root;
658 struct backref_node *cur;
659 struct backref_node *upper;
660 struct backref_node *lower;
661 struct backref_node *node = NULL;
662 struct backref_node *exist = NULL;
663 struct backref_edge *edge;
664 struct rb_node *rb_node;
665 struct btrfs_key key;
666 unsigned long end;
667 unsigned long ptr;
668 LIST_HEAD(list);
669 LIST_HEAD(useless);
670 int cowonly;
671 int ret;
672 int err = 0;
673
674 path1 = btrfs_alloc_path();
675 path2 = btrfs_alloc_path();
676 if (!path1 || !path2) {
677 err = -ENOMEM;
678 goto out;
679 }
680 path1->reada = 1;
681 path2->reada = 2;
682
683 node = alloc_backref_node(cache);
684 if (!node) {
685 err = -ENOMEM;
686 goto out;
687 }
688
689 node->bytenr = bytenr;
690 node->level = level;
691 node->lowest = 1;
692 cur = node;
693 again:
694 end = 0;
695 ptr = 0;
696 key.objectid = cur->bytenr;
697 key.type = BTRFS_EXTENT_ITEM_KEY;
698 key.offset = (u64)-1;
699
700 path1->search_commit_root = 1;
701 path1->skip_locking = 1;
702 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
703 0, 0);
704 if (ret < 0) {
705 err = ret;
706 goto out;
707 }
708 BUG_ON(!ret || !path1->slots[0]);
709
710 path1->slots[0]--;
711
712 WARN_ON(cur->checked);
713 if (!list_empty(&cur->upper)) {
714 /*
715 * the backref was added previously when processing
716 * backref of type BTRFS_TREE_BLOCK_REF_KEY
717 */
718 BUG_ON(!list_is_singular(&cur->upper));
719 edge = list_entry(cur->upper.next, struct backref_edge,
720 list[LOWER]);
721 BUG_ON(!list_empty(&edge->list[UPPER]));
722 exist = edge->node[UPPER];
723 /*
724 * add the upper level block to pending list if we need
725 * check its backrefs
726 */
727 if (!exist->checked)
728 list_add_tail(&edge->list[UPPER], &list);
729 } else {
730 exist = NULL;
731 }
732
733 while (1) {
734 cond_resched();
735 eb = path1->nodes[0];
736
737 if (ptr >= end) {
738 if (path1->slots[0] >= btrfs_header_nritems(eb)) {
739 ret = btrfs_next_leaf(rc->extent_root, path1);
740 if (ret < 0) {
741 err = ret;
742 goto out;
743 }
744 if (ret > 0)
745 break;
746 eb = path1->nodes[0];
747 }
748
749 btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
750 if (key.objectid != cur->bytenr) {
751 WARN_ON(exist);
752 break;
753 }
754
755 if (key.type == BTRFS_EXTENT_ITEM_KEY) {
756 ret = find_inline_backref(eb, path1->slots[0],
757 &ptr, &end);
758 if (ret)
759 goto next;
760 }
761 }
762
763 if (ptr < end) {
764 /* update key for inline back ref */
765 struct btrfs_extent_inline_ref *iref;
766 iref = (struct btrfs_extent_inline_ref *)ptr;
767 key.type = btrfs_extent_inline_ref_type(eb, iref);
768 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
769 WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
770 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
771 }
772
773 if (exist &&
774 ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
775 exist->owner == key.offset) ||
776 (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
777 exist->bytenr == key.offset))) {
778 exist = NULL;
779 goto next;
780 }
781
782 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
783 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
784 key.type == BTRFS_EXTENT_REF_V0_KEY) {
785 if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
786 struct btrfs_extent_ref_v0 *ref0;
787 ref0 = btrfs_item_ptr(eb, path1->slots[0],
788 struct btrfs_extent_ref_v0);
789 if (key.objectid == key.offset) {
790 root = find_tree_root(rc, eb, ref0);
791 if (root && !should_ignore_root(root))
792 cur->root = root;
793 else
794 list_add(&cur->list, &useless);
795 break;
796 }
797 if (is_cowonly_root(btrfs_ref_root_v0(eb,
798 ref0)))
799 cur->cowonly = 1;
800 }
801 #else
802 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
803 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
804 #endif
805 if (key.objectid == key.offset) {
806 /*
807 * only root blocks of reloc trees use
808 * backref of this type.
809 */
810 root = find_reloc_root(rc, cur->bytenr);
811 BUG_ON(!root);
812 cur->root = root;
813 break;
814 }
815
816 edge = alloc_backref_edge(cache);
817 if (!edge) {
818 err = -ENOMEM;
819 goto out;
820 }
821 rb_node = tree_search(&cache->rb_root, key.offset);
822 if (!rb_node) {
823 upper = alloc_backref_node(cache);
824 if (!upper) {
825 free_backref_edge(cache, edge);
826 err = -ENOMEM;
827 goto out;
828 }
829 upper->bytenr = key.offset;
830 upper->level = cur->level + 1;
831 /*
832 * backrefs for the upper level block isn't
833 * cached, add the block to pending list
834 */
835 list_add_tail(&edge->list[UPPER], &list);
836 } else {
837 upper = rb_entry(rb_node, struct backref_node,
838 rb_node);
839 BUG_ON(!upper->checked);
840 INIT_LIST_HEAD(&edge->list[UPPER]);
841 }
842 list_add_tail(&edge->list[LOWER], &cur->upper);
843 edge->node[LOWER] = cur;
844 edge->node[UPPER] = upper;
845
846 goto next;
847 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
848 goto next;
849 }
850
851 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
852 root = read_fs_root(rc->extent_root->fs_info, key.offset);
853 if (IS_ERR(root)) {
854 err = PTR_ERR(root);
855 goto out;
856 }
857
858 if (!root->ref_cows)
859 cur->cowonly = 1;
860
861 if (btrfs_root_level(&root->root_item) == cur->level) {
862 /* tree root */
863 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
864 cur->bytenr);
865 if (should_ignore_root(root))
866 list_add(&cur->list, &useless);
867 else
868 cur->root = root;
869 break;
870 }
871
872 level = cur->level + 1;
873
874 /*
875 * searching the tree to find upper level blocks
876 * reference the block.
877 */
878 path2->search_commit_root = 1;
879 path2->skip_locking = 1;
880 path2->lowest_level = level;
881 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
882 path2->lowest_level = 0;
883 if (ret < 0) {
884 err = ret;
885 goto out;
886 }
887 if (ret > 0 && path2->slots[level] > 0)
888 path2->slots[level]--;
889
890 eb = path2->nodes[level];
891 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
892 cur->bytenr);
893
894 lower = cur;
895 for (; level < BTRFS_MAX_LEVEL; level++) {
896 if (!path2->nodes[level]) {
897 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
898 lower->bytenr);
899 if (should_ignore_root(root))
900 list_add(&lower->list, &useless);
901 else
902 lower->root = root;
903 break;
904 }
905
906 edge = alloc_backref_edge(cache);
907 if (!edge) {
908 err = -ENOMEM;
909 goto out;
910 }
911
912 eb = path2->nodes[level];
913 rb_node = tree_search(&cache->rb_root, eb->start);
914 if (!rb_node) {
915 upper = alloc_backref_node(cache);
916 if (!upper) {
917 free_backref_edge(cache, edge);
918 err = -ENOMEM;
919 goto out;
920 }
921 upper->bytenr = eb->start;
922 upper->owner = btrfs_header_owner(eb);
923 upper->level = lower->level + 1;
924 if (!root->ref_cows)
925 upper->cowonly = 1;
926
927 /*
928 * if we know the block isn't shared
929 * we can void checking its backrefs.
930 */
931 if (btrfs_block_can_be_shared(root, eb))
932 upper->checked = 0;
933 else
934 upper->checked = 1;
935
936 /*
937 * add the block to pending list if we
938 * need check its backrefs. only block
939 * at 'cur->level + 1' is added to the
940 * tail of pending list. this guarantees
941 * we check backrefs from lower level
942 * blocks to upper level blocks.
943 */
944 if (!upper->checked &&
945 level == cur->level + 1) {
946 list_add_tail(&edge->list[UPPER],
947 &list);
948 } else
949 INIT_LIST_HEAD(&edge->list[UPPER]);
950 } else {
951 upper = rb_entry(rb_node, struct backref_node,
952 rb_node);
953 BUG_ON(!upper->checked);
954 INIT_LIST_HEAD(&edge->list[UPPER]);
955 if (!upper->owner)
956 upper->owner = btrfs_header_owner(eb);
957 }
958 list_add_tail(&edge->list[LOWER], &lower->upper);
959 edge->node[LOWER] = lower;
960 edge->node[UPPER] = upper;
961
962 if (rb_node)
963 break;
964 lower = upper;
965 upper = NULL;
966 }
967 btrfs_release_path(path2);
968 next:
969 if (ptr < end) {
970 ptr += btrfs_extent_inline_ref_size(key.type);
971 if (ptr >= end) {
972 WARN_ON(ptr > end);
973 ptr = 0;
974 end = 0;
975 }
976 }
977 if (ptr >= end)
978 path1->slots[0]++;
979 }
980 btrfs_release_path(path1);
981
982 cur->checked = 1;
983 WARN_ON(exist);
984
985 /* the pending list isn't empty, take the first block to process */
986 if (!list_empty(&list)) {
987 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
988 list_del_init(&edge->list[UPPER]);
989 cur = edge->node[UPPER];
990 goto again;
991 }
992
993 /*
994 * everything goes well, connect backref nodes and insert backref nodes
995 * into the cache.
996 */
997 BUG_ON(!node->checked);
998 cowonly = node->cowonly;
999 if (!cowonly) {
1000 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1001 &node->rb_node);
1002 BUG_ON(rb_node);
1003 list_add_tail(&node->lower, &cache->leaves);
1004 }
1005
1006 list_for_each_entry(edge, &node->upper, list[LOWER])
1007 list_add_tail(&edge->list[UPPER], &list);
1008
1009 while (!list_empty(&list)) {
1010 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1011 list_del_init(&edge->list[UPPER]);
1012 upper = edge->node[UPPER];
1013 if (upper->detached) {
1014 list_del(&edge->list[LOWER]);
1015 lower = edge->node[LOWER];
1016 free_backref_edge(cache, edge);
1017 if (list_empty(&lower->upper))
1018 list_add(&lower->list, &useless);
1019 continue;
1020 }
1021
1022 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1023 if (upper->lowest) {
1024 list_del_init(&upper->lower);
1025 upper->lowest = 0;
1026 }
1027
1028 list_add_tail(&edge->list[UPPER], &upper->lower);
1029 continue;
1030 }
1031
1032 BUG_ON(!upper->checked);
1033 BUG_ON(cowonly != upper->cowonly);
1034 if (!cowonly) {
1035 rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1036 &upper->rb_node);
1037 BUG_ON(rb_node);
1038 }
1039
1040 list_add_tail(&edge->list[UPPER], &upper->lower);
1041
1042 list_for_each_entry(edge, &upper->upper, list[LOWER])
1043 list_add_tail(&edge->list[UPPER], &list);
1044 }
1045 /*
1046 * process useless backref nodes. backref nodes for tree leaves
1047 * are deleted from the cache. backref nodes for upper level
1048 * tree blocks are left in the cache to avoid unnecessary backref
1049 * lookup.
1050 */
1051 while (!list_empty(&useless)) {
1052 upper = list_entry(useless.next, struct backref_node, list);
1053 list_del_init(&upper->list);
1054 BUG_ON(!list_empty(&upper->upper));
1055 if (upper == node)
1056 node = NULL;
1057 if (upper->lowest) {
1058 list_del_init(&upper->lower);
1059 upper->lowest = 0;
1060 }
1061 while (!list_empty(&upper->lower)) {
1062 edge = list_entry(upper->lower.next,
1063 struct backref_edge, list[UPPER]);
1064 list_del(&edge->list[UPPER]);
1065 list_del(&edge->list[LOWER]);
1066 lower = edge->node[LOWER];
1067 free_backref_edge(cache, edge);
1068
1069 if (list_empty(&lower->upper))
1070 list_add(&lower->list, &useless);
1071 }
1072 __mark_block_processed(rc, upper);
1073 if (upper->level > 0) {
1074 list_add(&upper->list, &cache->detached);
1075 upper->detached = 1;
1076 } else {
1077 rb_erase(&upper->rb_node, &cache->rb_root);
1078 free_backref_node(cache, upper);
1079 }
1080 }
1081 out:
1082 btrfs_free_path(path1);
1083 btrfs_free_path(path2);
1084 if (err) {
1085 while (!list_empty(&useless)) {
1086 lower = list_entry(useless.next,
1087 struct backref_node, upper);
1088 list_del_init(&lower->upper);
1089 }
1090 upper = node;
1091 INIT_LIST_HEAD(&list);
1092 while (upper) {
1093 if (RB_EMPTY_NODE(&upper->rb_node)) {
1094 list_splice_tail(&upper->upper, &list);
1095 free_backref_node(cache, upper);
1096 }
1097
1098 if (list_empty(&list))
1099 break;
1100
1101 edge = list_entry(list.next, struct backref_edge,
1102 list[LOWER]);
1103 list_del(&edge->list[LOWER]);
1104 upper = edge->node[UPPER];
1105 free_backref_edge(cache, edge);
1106 }
1107 return ERR_PTR(err);
1108 }
1109 BUG_ON(node && node->detached);
1110 return node;
1111 }
1112
1113 /*
1114 * helper to add backref node for the newly created snapshot.
1115 * the backref node is created by cloning backref node that
1116 * corresponds to root of source tree
1117 */
1118 static int clone_backref_node(struct btrfs_trans_handle *trans,
1119 struct reloc_control *rc,
1120 struct btrfs_root *src,
1121 struct btrfs_root *dest)
1122 {
1123 struct btrfs_root *reloc_root = src->reloc_root;
1124 struct backref_cache *cache = &rc->backref_cache;
1125 struct backref_node *node = NULL;
1126 struct backref_node *new_node;
1127 struct backref_edge *edge;
1128 struct backref_edge *new_edge;
1129 struct rb_node *rb_node;
1130
1131 if (cache->last_trans > 0)
1132 update_backref_cache(trans, cache);
1133
1134 rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1135 if (rb_node) {
1136 node = rb_entry(rb_node, struct backref_node, rb_node);
1137 if (node->detached)
1138 node = NULL;
1139 else
1140 BUG_ON(node->new_bytenr != reloc_root->node->start);
1141 }
1142
1143 if (!node) {
1144 rb_node = tree_search(&cache->rb_root,
1145 reloc_root->commit_root->start);
1146 if (rb_node) {
1147 node = rb_entry(rb_node, struct backref_node,
1148 rb_node);
1149 BUG_ON(node->detached);
1150 }
1151 }
1152
1153 if (!node)
1154 return 0;
1155
1156 new_node = alloc_backref_node(cache);
1157 if (!new_node)
1158 return -ENOMEM;
1159
1160 new_node->bytenr = dest->node->start;
1161 new_node->level = node->level;
1162 new_node->lowest = node->lowest;
1163 new_node->checked = 1;
1164 new_node->root = dest;
1165
1166 if (!node->lowest) {
1167 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1168 new_edge = alloc_backref_edge(cache);
1169 if (!new_edge)
1170 goto fail;
1171
1172 new_edge->node[UPPER] = new_node;
1173 new_edge->node[LOWER] = edge->node[LOWER];
1174 list_add_tail(&new_edge->list[UPPER],
1175 &new_node->lower);
1176 }
1177 } else {
1178 list_add_tail(&new_node->lower, &cache->leaves);
1179 }
1180
1181 rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1182 &new_node->rb_node);
1183 BUG_ON(rb_node);
1184
1185 if (!new_node->lowest) {
1186 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1187 list_add_tail(&new_edge->list[LOWER],
1188 &new_edge->node[LOWER]->upper);
1189 }
1190 }
1191 return 0;
1192 fail:
1193 while (!list_empty(&new_node->lower)) {
1194 new_edge = list_entry(new_node->lower.next,
1195 struct backref_edge, list[UPPER]);
1196 list_del(&new_edge->list[UPPER]);
1197 free_backref_edge(cache, new_edge);
1198 }
1199 free_backref_node(cache, new_node);
1200 return -ENOMEM;
1201 }
1202
1203 /*
1204 * helper to add 'address of tree root -> reloc tree' mapping
1205 */
1206 static int __add_reloc_root(struct btrfs_root *root)
1207 {
1208 struct rb_node *rb_node;
1209 struct mapping_node *node;
1210 struct reloc_control *rc = root->fs_info->reloc_ctl;
1211
1212 node = kmalloc(sizeof(*node), GFP_NOFS);
1213 BUG_ON(!node);
1214
1215 node->bytenr = root->node->start;
1216 node->data = root;
1217
1218 spin_lock(&rc->reloc_root_tree.lock);
1219 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1220 node->bytenr, &node->rb_node);
1221 spin_unlock(&rc->reloc_root_tree.lock);
1222 BUG_ON(rb_node);
1223
1224 list_add_tail(&root->root_list, &rc->reloc_roots);
1225 return 0;
1226 }
1227
1228 /*
1229 * helper to update/delete the 'address of tree root -> reloc tree'
1230 * mapping
1231 */
1232 static int __update_reloc_root(struct btrfs_root *root, int del)
1233 {
1234 struct rb_node *rb_node;
1235 struct mapping_node *node = NULL;
1236 struct reloc_control *rc = root->fs_info->reloc_ctl;
1237
1238 spin_lock(&rc->reloc_root_tree.lock);
1239 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1240 root->commit_root->start);
1241 if (rb_node) {
1242 node = rb_entry(rb_node, struct mapping_node, rb_node);
1243 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1244 }
1245 spin_unlock(&rc->reloc_root_tree.lock);
1246
1247 BUG_ON((struct btrfs_root *)node->data != root);
1248
1249 if (!del) {
1250 spin_lock(&rc->reloc_root_tree.lock);
1251 node->bytenr = root->node->start;
1252 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1253 node->bytenr, &node->rb_node);
1254 spin_unlock(&rc->reloc_root_tree.lock);
1255 BUG_ON(rb_node);
1256 } else {
1257 list_del_init(&root->root_list);
1258 kfree(node);
1259 }
1260 return 0;
1261 }
1262
1263 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1264 struct btrfs_root *root, u64 objectid)
1265 {
1266 struct btrfs_root *reloc_root;
1267 struct extent_buffer *eb;
1268 struct btrfs_root_item *root_item;
1269 struct btrfs_key root_key;
1270 int ret;
1271
1272 root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1273 BUG_ON(!root_item);
1274
1275 root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1276 root_key.type = BTRFS_ROOT_ITEM_KEY;
1277 root_key.offset = objectid;
1278
1279 if (root->root_key.objectid == objectid) {
1280 /* called by btrfs_init_reloc_root */
1281 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1282 BTRFS_TREE_RELOC_OBJECTID);
1283 BUG_ON(ret);
1284
1285 btrfs_set_root_last_snapshot(&root->root_item,
1286 trans->transid - 1);
1287 } else {
1288 /*
1289 * called by btrfs_reloc_post_snapshot_hook.
1290 * the source tree is a reloc tree, all tree blocks
1291 * modified after it was created have RELOC flag
1292 * set in their headers. so it's OK to not update
1293 * the 'last_snapshot'.
1294 */
1295 ret = btrfs_copy_root(trans, root, root->node, &eb,
1296 BTRFS_TREE_RELOC_OBJECTID);
1297 BUG_ON(ret);
1298 }
1299
1300 memcpy(root_item, &root->root_item, sizeof(*root_item));
1301 btrfs_set_root_bytenr(root_item, eb->start);
1302 btrfs_set_root_level(root_item, btrfs_header_level(eb));
1303 btrfs_set_root_generation(root_item, trans->transid);
1304
1305 if (root->root_key.objectid == objectid) {
1306 btrfs_set_root_refs(root_item, 0);
1307 memset(&root_item->drop_progress, 0,
1308 sizeof(struct btrfs_disk_key));
1309 root_item->drop_level = 0;
1310 }
1311
1312 btrfs_tree_unlock(eb);
1313 free_extent_buffer(eb);
1314
1315 ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1316 &root_key, root_item);
1317 BUG_ON(ret);
1318 kfree(root_item);
1319
1320 reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
1321 &root_key);
1322 BUG_ON(IS_ERR(reloc_root));
1323 reloc_root->last_trans = trans->transid;
1324 return reloc_root;
1325 }
1326
1327 /*
1328 * create reloc tree for a given fs tree. reloc tree is just a
1329 * snapshot of the fs tree with special root objectid.
1330 */
1331 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1332 struct btrfs_root *root)
1333 {
1334 struct btrfs_root *reloc_root;
1335 struct reloc_control *rc = root->fs_info->reloc_ctl;
1336 int clear_rsv = 0;
1337
1338 if (root->reloc_root) {
1339 reloc_root = root->reloc_root;
1340 reloc_root->last_trans = trans->transid;
1341 return 0;
1342 }
1343
1344 if (!rc || !rc->create_reloc_tree ||
1345 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1346 return 0;
1347
1348 if (!trans->block_rsv) {
1349 trans->block_rsv = rc->block_rsv;
1350 clear_rsv = 1;
1351 }
1352 reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1353 if (clear_rsv)
1354 trans->block_rsv = NULL;
1355
1356 __add_reloc_root(reloc_root);
1357 root->reloc_root = reloc_root;
1358 return 0;
1359 }
1360
1361 /*
1362 * update root item of reloc tree
1363 */
1364 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1365 struct btrfs_root *root)
1366 {
1367 struct btrfs_root *reloc_root;
1368 struct btrfs_root_item *root_item;
1369 int del = 0;
1370 int ret;
1371
1372 if (!root->reloc_root)
1373 goto out;
1374
1375 reloc_root = root->reloc_root;
1376 root_item = &reloc_root->root_item;
1377
1378 if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1379 btrfs_root_refs(root_item) == 0) {
1380 root->reloc_root = NULL;
1381 del = 1;
1382 }
1383
1384 __update_reloc_root(reloc_root, del);
1385
1386 if (reloc_root->commit_root != reloc_root->node) {
1387 btrfs_set_root_node(root_item, reloc_root->node);
1388 free_extent_buffer(reloc_root->commit_root);
1389 reloc_root->commit_root = btrfs_root_node(reloc_root);
1390 }
1391
1392 ret = btrfs_update_root(trans, root->fs_info->tree_root,
1393 &reloc_root->root_key, root_item);
1394 BUG_ON(ret);
1395
1396 out:
1397 return 0;
1398 }
1399
1400 /*
1401 * helper to find first cached inode with inode number >= objectid
1402 * in a subvolume
1403 */
1404 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1405 {
1406 struct rb_node *node;
1407 struct rb_node *prev;
1408 struct btrfs_inode *entry;
1409 struct inode *inode;
1410
1411 spin_lock(&root->inode_lock);
1412 again:
1413 node = root->inode_tree.rb_node;
1414 prev = NULL;
1415 while (node) {
1416 prev = node;
1417 entry = rb_entry(node, struct btrfs_inode, rb_node);
1418
1419 if (objectid < btrfs_ino(&entry->vfs_inode))
1420 node = node->rb_left;
1421 else if (objectid > btrfs_ino(&entry->vfs_inode))
1422 node = node->rb_right;
1423 else
1424 break;
1425 }
1426 if (!node) {
1427 while (prev) {
1428 entry = rb_entry(prev, struct btrfs_inode, rb_node);
1429 if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1430 node = prev;
1431 break;
1432 }
1433 prev = rb_next(prev);
1434 }
1435 }
1436 while (node) {
1437 entry = rb_entry(node, struct btrfs_inode, rb_node);
1438 inode = igrab(&entry->vfs_inode);
1439 if (inode) {
1440 spin_unlock(&root->inode_lock);
1441 return inode;
1442 }
1443
1444 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1445 if (cond_resched_lock(&root->inode_lock))
1446 goto again;
1447
1448 node = rb_next(node);
1449 }
1450 spin_unlock(&root->inode_lock);
1451 return NULL;
1452 }
1453
1454 static int in_block_group(u64 bytenr,
1455 struct btrfs_block_group_cache *block_group)
1456 {
1457 if (bytenr >= block_group->key.objectid &&
1458 bytenr < block_group->key.objectid + block_group->key.offset)
1459 return 1;
1460 return 0;
1461 }
1462
1463 /*
1464 * get new location of data
1465 */
1466 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1467 u64 bytenr, u64 num_bytes)
1468 {
1469 struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1470 struct btrfs_path *path;
1471 struct btrfs_file_extent_item *fi;
1472 struct extent_buffer *leaf;
1473 int ret;
1474
1475 path = btrfs_alloc_path();
1476 if (!path)
1477 return -ENOMEM;
1478
1479 bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1480 ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1481 bytenr, 0);
1482 if (ret < 0)
1483 goto out;
1484 if (ret > 0) {
1485 ret = -ENOENT;
1486 goto out;
1487 }
1488
1489 leaf = path->nodes[0];
1490 fi = btrfs_item_ptr(leaf, path->slots[0],
1491 struct btrfs_file_extent_item);
1492
1493 BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1494 btrfs_file_extent_compression(leaf, fi) ||
1495 btrfs_file_extent_encryption(leaf, fi) ||
1496 btrfs_file_extent_other_encoding(leaf, fi));
1497
1498 if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1499 ret = 1;
1500 goto out;
1501 }
1502
1503 *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1504 ret = 0;
1505 out:
1506 btrfs_free_path(path);
1507 return ret;
1508 }
1509
1510 /*
1511 * update file extent items in the tree leaf to point to
1512 * the new locations.
1513 */
1514 static noinline_for_stack
1515 int replace_file_extents(struct btrfs_trans_handle *trans,
1516 struct reloc_control *rc,
1517 struct btrfs_root *root,
1518 struct extent_buffer *leaf)
1519 {
1520 struct btrfs_key key;
1521 struct btrfs_file_extent_item *fi;
1522 struct inode *inode = NULL;
1523 u64 parent;
1524 u64 bytenr;
1525 u64 new_bytenr = 0;
1526 u64 num_bytes;
1527 u64 end;
1528 u32 nritems;
1529 u32 i;
1530 int ret;
1531 int first = 1;
1532 int dirty = 0;
1533
1534 if (rc->stage != UPDATE_DATA_PTRS)
1535 return 0;
1536
1537 /* reloc trees always use full backref */
1538 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1539 parent = leaf->start;
1540 else
1541 parent = 0;
1542
1543 nritems = btrfs_header_nritems(leaf);
1544 for (i = 0; i < nritems; i++) {
1545 cond_resched();
1546 btrfs_item_key_to_cpu(leaf, &key, i);
1547 if (key.type != BTRFS_EXTENT_DATA_KEY)
1548 continue;
1549 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1550 if (btrfs_file_extent_type(leaf, fi) ==
1551 BTRFS_FILE_EXTENT_INLINE)
1552 continue;
1553 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1554 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1555 if (bytenr == 0)
1556 continue;
1557 if (!in_block_group(bytenr, rc->block_group))
1558 continue;
1559
1560 /*
1561 * if we are modifying block in fs tree, wait for readpage
1562 * to complete and drop the extent cache
1563 */
1564 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1565 if (first) {
1566 inode = find_next_inode(root, key.objectid);
1567 first = 0;
1568 } else if (inode && btrfs_ino(inode) < key.objectid) {
1569 btrfs_add_delayed_iput(inode);
1570 inode = find_next_inode(root, key.objectid);
1571 }
1572 if (inode && btrfs_ino(inode) == key.objectid) {
1573 end = key.offset +
1574 btrfs_file_extent_num_bytes(leaf, fi);
1575 WARN_ON(!IS_ALIGNED(key.offset,
1576 root->sectorsize));
1577 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1578 end--;
1579 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1580 key.offset, end,
1581 GFP_NOFS);
1582 if (!ret)
1583 continue;
1584
1585 btrfs_drop_extent_cache(inode, key.offset, end,
1586 1);
1587 unlock_extent(&BTRFS_I(inode)->io_tree,
1588 key.offset, end, GFP_NOFS);
1589 }
1590 }
1591
1592 ret = get_new_location(rc->data_inode, &new_bytenr,
1593 bytenr, num_bytes);
1594 if (ret > 0) {
1595 WARN_ON(1);
1596 continue;
1597 }
1598 BUG_ON(ret < 0);
1599
1600 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1601 dirty = 1;
1602
1603 key.offset -= btrfs_file_extent_offset(leaf, fi);
1604 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1605 num_bytes, parent,
1606 btrfs_header_owner(leaf),
1607 key.objectid, key.offset);
1608 BUG_ON(ret);
1609
1610 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1611 parent, btrfs_header_owner(leaf),
1612 key.objectid, key.offset);
1613 BUG_ON(ret);
1614 }
1615 if (dirty)
1616 btrfs_mark_buffer_dirty(leaf);
1617 if (inode)
1618 btrfs_add_delayed_iput(inode);
1619 return 0;
1620 }
1621
1622 static noinline_for_stack
1623 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1624 struct btrfs_path *path, int level)
1625 {
1626 struct btrfs_disk_key key1;
1627 struct btrfs_disk_key key2;
1628 btrfs_node_key(eb, &key1, slot);
1629 btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1630 return memcmp(&key1, &key2, sizeof(key1));
1631 }
1632
1633 /*
1634 * try to replace tree blocks in fs tree with the new blocks
1635 * in reloc tree. tree blocks haven't been modified since the
1636 * reloc tree was create can be replaced.
1637 *
1638 * if a block was replaced, level of the block + 1 is returned.
1639 * if no block got replaced, 0 is returned. if there are other
1640 * errors, a negative error number is returned.
1641 */
1642 static noinline_for_stack
1643 int replace_path(struct btrfs_trans_handle *trans,
1644 struct btrfs_root *dest, struct btrfs_root *src,
1645 struct btrfs_path *path, struct btrfs_key *next_key,
1646 int lowest_level, int max_level)
1647 {
1648 struct extent_buffer *eb;
1649 struct extent_buffer *parent;
1650 struct btrfs_key key;
1651 u64 old_bytenr;
1652 u64 new_bytenr;
1653 u64 old_ptr_gen;
1654 u64 new_ptr_gen;
1655 u64 last_snapshot;
1656 u32 blocksize;
1657 int cow = 0;
1658 int level;
1659 int ret;
1660 int slot;
1661
1662 BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1663 BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1664
1665 last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1666 again:
1667 slot = path->slots[lowest_level];
1668 btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1669
1670 eb = btrfs_lock_root_node(dest);
1671 btrfs_set_lock_blocking(eb);
1672 level = btrfs_header_level(eb);
1673
1674 if (level < lowest_level) {
1675 btrfs_tree_unlock(eb);
1676 free_extent_buffer(eb);
1677 return 0;
1678 }
1679
1680 if (cow) {
1681 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1682 BUG_ON(ret);
1683 }
1684 btrfs_set_lock_blocking(eb);
1685
1686 if (next_key) {
1687 next_key->objectid = (u64)-1;
1688 next_key->type = (u8)-1;
1689 next_key->offset = (u64)-1;
1690 }
1691
1692 parent = eb;
1693 while (1) {
1694 level = btrfs_header_level(parent);
1695 BUG_ON(level < lowest_level);
1696
1697 ret = btrfs_bin_search(parent, &key, level, &slot);
1698 if (ret && slot > 0)
1699 slot--;
1700
1701 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1702 btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1703
1704 old_bytenr = btrfs_node_blockptr(parent, slot);
1705 blocksize = btrfs_level_size(dest, level - 1);
1706 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1707
1708 if (level <= max_level) {
1709 eb = path->nodes[level];
1710 new_bytenr = btrfs_node_blockptr(eb,
1711 path->slots[level]);
1712 new_ptr_gen = btrfs_node_ptr_generation(eb,
1713 path->slots[level]);
1714 } else {
1715 new_bytenr = 0;
1716 new_ptr_gen = 0;
1717 }
1718
1719 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1720 WARN_ON(1);
1721 ret = level;
1722 break;
1723 }
1724
1725 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1726 memcmp_node_keys(parent, slot, path, level)) {
1727 if (level <= lowest_level) {
1728 ret = 0;
1729 break;
1730 }
1731
1732 eb = read_tree_block(dest, old_bytenr, blocksize,
1733 old_ptr_gen);
1734 BUG_ON(!eb);
1735 btrfs_tree_lock(eb);
1736 if (cow) {
1737 ret = btrfs_cow_block(trans, dest, eb, parent,
1738 slot, &eb);
1739 BUG_ON(ret);
1740 }
1741 btrfs_set_lock_blocking(eb);
1742
1743 btrfs_tree_unlock(parent);
1744 free_extent_buffer(parent);
1745
1746 parent = eb;
1747 continue;
1748 }
1749
1750 if (!cow) {
1751 btrfs_tree_unlock(parent);
1752 free_extent_buffer(parent);
1753 cow = 1;
1754 goto again;
1755 }
1756
1757 btrfs_node_key_to_cpu(path->nodes[level], &key,
1758 path->slots[level]);
1759 btrfs_release_path(path);
1760
1761 path->lowest_level = level;
1762 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1763 path->lowest_level = 0;
1764 BUG_ON(ret);
1765
1766 /*
1767 * swap blocks in fs tree and reloc tree.
1768 */
1769 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1770 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1771 btrfs_mark_buffer_dirty(parent);
1772
1773 btrfs_set_node_blockptr(path->nodes[level],
1774 path->slots[level], old_bytenr);
1775 btrfs_set_node_ptr_generation(path->nodes[level],
1776 path->slots[level], old_ptr_gen);
1777 btrfs_mark_buffer_dirty(path->nodes[level]);
1778
1779 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1780 path->nodes[level]->start,
1781 src->root_key.objectid, level - 1, 0);
1782 BUG_ON(ret);
1783 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1784 0, dest->root_key.objectid, level - 1,
1785 0);
1786 BUG_ON(ret);
1787
1788 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1789 path->nodes[level]->start,
1790 src->root_key.objectid, level - 1, 0);
1791 BUG_ON(ret);
1792
1793 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1794 0, dest->root_key.objectid, level - 1,
1795 0);
1796 BUG_ON(ret);
1797
1798 btrfs_unlock_up_safe(path, 0);
1799
1800 ret = level;
1801 break;
1802 }
1803 btrfs_tree_unlock(parent);
1804 free_extent_buffer(parent);
1805 return ret;
1806 }
1807
1808 /*
1809 * helper to find next relocated block in reloc tree
1810 */
1811 static noinline_for_stack
1812 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1813 int *level)
1814 {
1815 struct extent_buffer *eb;
1816 int i;
1817 u64 last_snapshot;
1818 u32 nritems;
1819
1820 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1821
1822 for (i = 0; i < *level; i++) {
1823 free_extent_buffer(path->nodes[i]);
1824 path->nodes[i] = NULL;
1825 }
1826
1827 for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1828 eb = path->nodes[i];
1829 nritems = btrfs_header_nritems(eb);
1830 while (path->slots[i] + 1 < nritems) {
1831 path->slots[i]++;
1832 if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1833 last_snapshot)
1834 continue;
1835
1836 *level = i;
1837 return 0;
1838 }
1839 free_extent_buffer(path->nodes[i]);
1840 path->nodes[i] = NULL;
1841 }
1842 return 1;
1843 }
1844
1845 /*
1846 * walk down reloc tree to find relocated block of lowest level
1847 */
1848 static noinline_for_stack
1849 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1850 int *level)
1851 {
1852 struct extent_buffer *eb = NULL;
1853 int i;
1854 u64 bytenr;
1855 u64 ptr_gen = 0;
1856 u64 last_snapshot;
1857 u32 blocksize;
1858 u32 nritems;
1859
1860 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1861
1862 for (i = *level; i > 0; i--) {
1863 eb = path->nodes[i];
1864 nritems = btrfs_header_nritems(eb);
1865 while (path->slots[i] < nritems) {
1866 ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1867 if (ptr_gen > last_snapshot)
1868 break;
1869 path->slots[i]++;
1870 }
1871 if (path->slots[i] >= nritems) {
1872 if (i == *level)
1873 break;
1874 *level = i + 1;
1875 return 0;
1876 }
1877 if (i == 1) {
1878 *level = i;
1879 return 0;
1880 }
1881
1882 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1883 blocksize = btrfs_level_size(root, i - 1);
1884 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1885 BUG_ON(btrfs_header_level(eb) != i - 1);
1886 path->nodes[i - 1] = eb;
1887 path->slots[i - 1] = 0;
1888 }
1889 return 1;
1890 }
1891
1892 /*
1893 * invalidate extent cache for file extents whose key in range of
1894 * [min_key, max_key)
1895 */
1896 static int invalidate_extent_cache(struct btrfs_root *root,
1897 struct btrfs_key *min_key,
1898 struct btrfs_key *max_key)
1899 {
1900 struct inode *inode = NULL;
1901 u64 objectid;
1902 u64 start, end;
1903 u64 ino;
1904
1905 objectid = min_key->objectid;
1906 while (1) {
1907 cond_resched();
1908 iput(inode);
1909
1910 if (objectid > max_key->objectid)
1911 break;
1912
1913 inode = find_next_inode(root, objectid);
1914 if (!inode)
1915 break;
1916 ino = btrfs_ino(inode);
1917
1918 if (ino > max_key->objectid) {
1919 iput(inode);
1920 break;
1921 }
1922
1923 objectid = ino + 1;
1924 if (!S_ISREG(inode->i_mode))
1925 continue;
1926
1927 if (unlikely(min_key->objectid == ino)) {
1928 if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1929 continue;
1930 if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1931 start = 0;
1932 else {
1933 start = min_key->offset;
1934 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1935 }
1936 } else {
1937 start = 0;
1938 }
1939
1940 if (unlikely(max_key->objectid == ino)) {
1941 if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1942 continue;
1943 if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1944 end = (u64)-1;
1945 } else {
1946 if (max_key->offset == 0)
1947 continue;
1948 end = max_key->offset;
1949 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1950 end--;
1951 }
1952 } else {
1953 end = (u64)-1;
1954 }
1955
1956 /* the lock_extent waits for readpage to complete */
1957 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1958 btrfs_drop_extent_cache(inode, start, end, 1);
1959 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1960 }
1961 return 0;
1962 }
1963
1964 static int find_next_key(struct btrfs_path *path, int level,
1965 struct btrfs_key *key)
1966
1967 {
1968 while (level < BTRFS_MAX_LEVEL) {
1969 if (!path->nodes[level])
1970 break;
1971 if (path->slots[level] + 1 <
1972 btrfs_header_nritems(path->nodes[level])) {
1973 btrfs_node_key_to_cpu(path->nodes[level], key,
1974 path->slots[level] + 1);
1975 return 0;
1976 }
1977 level++;
1978 }
1979 return 1;
1980 }
1981
1982 /*
1983 * merge the relocated tree blocks in reloc tree with corresponding
1984 * fs tree.
1985 */
1986 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
1987 struct btrfs_root *root)
1988 {
1989 LIST_HEAD(inode_list);
1990 struct btrfs_key key;
1991 struct btrfs_key next_key;
1992 struct btrfs_trans_handle *trans;
1993 struct btrfs_root *reloc_root;
1994 struct btrfs_root_item *root_item;
1995 struct btrfs_path *path;
1996 struct extent_buffer *leaf;
1997 unsigned long nr;
1998 int level;
1999 int max_level;
2000 int replaced = 0;
2001 int ret;
2002 int err = 0;
2003 u32 min_reserved;
2004
2005 path = btrfs_alloc_path();
2006 if (!path)
2007 return -ENOMEM;
2008 path->reada = 1;
2009
2010 reloc_root = root->reloc_root;
2011 root_item = &reloc_root->root_item;
2012
2013 if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2014 level = btrfs_root_level(root_item);
2015 extent_buffer_get(reloc_root->node);
2016 path->nodes[level] = reloc_root->node;
2017 path->slots[level] = 0;
2018 } else {
2019 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2020
2021 level = root_item->drop_level;
2022 BUG_ON(level == 0);
2023 path->lowest_level = level;
2024 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2025 path->lowest_level = 0;
2026 if (ret < 0) {
2027 btrfs_free_path(path);
2028 return ret;
2029 }
2030
2031 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2032 path->slots[level]);
2033 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2034
2035 btrfs_unlock_up_safe(path, 0);
2036 }
2037
2038 min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2039 memset(&next_key, 0, sizeof(next_key));
2040
2041 while (1) {
2042 trans = btrfs_start_transaction(root, 0);
2043 BUG_ON(IS_ERR(trans));
2044 trans->block_rsv = rc->block_rsv;
2045
2046 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved);
2047 if (ret) {
2048 BUG_ON(ret != -EAGAIN);
2049 ret = btrfs_commit_transaction(trans, root);
2050 BUG_ON(ret);
2051 continue;
2052 }
2053
2054 replaced = 0;
2055 max_level = level;
2056
2057 ret = walk_down_reloc_tree(reloc_root, path, &level);
2058 if (ret < 0) {
2059 err = ret;
2060 goto out;
2061 }
2062 if (ret > 0)
2063 break;
2064
2065 if (!find_next_key(path, level, &key) &&
2066 btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2067 ret = 0;
2068 } else {
2069 ret = replace_path(trans, root, reloc_root, path,
2070 &next_key, level, max_level);
2071 }
2072 if (ret < 0) {
2073 err = ret;
2074 goto out;
2075 }
2076
2077 if (ret > 0) {
2078 level = ret;
2079 btrfs_node_key_to_cpu(path->nodes[level], &key,
2080 path->slots[level]);
2081 replaced = 1;
2082 }
2083
2084 ret = walk_up_reloc_tree(reloc_root, path, &level);
2085 if (ret > 0)
2086 break;
2087
2088 BUG_ON(level == 0);
2089 /*
2090 * save the merging progress in the drop_progress.
2091 * this is OK since root refs == 1 in this case.
2092 */
2093 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2094 path->slots[level]);
2095 root_item->drop_level = level;
2096
2097 nr = trans->blocks_used;
2098 btrfs_end_transaction_throttle(trans, root);
2099
2100 btrfs_btree_balance_dirty(root, nr);
2101
2102 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2103 invalidate_extent_cache(root, &key, &next_key);
2104 }
2105
2106 /*
2107 * handle the case only one block in the fs tree need to be
2108 * relocated and the block is tree root.
2109 */
2110 leaf = btrfs_lock_root_node(root);
2111 ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2112 btrfs_tree_unlock(leaf);
2113 free_extent_buffer(leaf);
2114 if (ret < 0)
2115 err = ret;
2116 out:
2117 btrfs_free_path(path);
2118
2119 if (err == 0) {
2120 memset(&root_item->drop_progress, 0,
2121 sizeof(root_item->drop_progress));
2122 root_item->drop_level = 0;
2123 btrfs_set_root_refs(root_item, 0);
2124 btrfs_update_reloc_root(trans, root);
2125 }
2126
2127 nr = trans->blocks_used;
2128 btrfs_end_transaction_throttle(trans, root);
2129
2130 btrfs_btree_balance_dirty(root, nr);
2131
2132 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2133 invalidate_extent_cache(root, &key, &next_key);
2134
2135 return err;
2136 }
2137
2138 static noinline_for_stack
2139 int prepare_to_merge(struct reloc_control *rc, int err)
2140 {
2141 struct btrfs_root *root = rc->extent_root;
2142 struct btrfs_root *reloc_root;
2143 struct btrfs_trans_handle *trans;
2144 LIST_HEAD(reloc_roots);
2145 u64 num_bytes = 0;
2146 int ret;
2147
2148 mutex_lock(&root->fs_info->reloc_mutex);
2149 rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2150 rc->merging_rsv_size += rc->nodes_relocated * 2;
2151 mutex_unlock(&root->fs_info->reloc_mutex);
2152
2153 again:
2154 if (!err) {
2155 num_bytes = rc->merging_rsv_size;
2156 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes);
2157 if (ret)
2158 err = ret;
2159 }
2160
2161 trans = btrfs_join_transaction(rc->extent_root);
2162 if (IS_ERR(trans)) {
2163 if (!err)
2164 btrfs_block_rsv_release(rc->extent_root,
2165 rc->block_rsv, num_bytes);
2166 return PTR_ERR(trans);
2167 }
2168
2169 if (!err) {
2170 if (num_bytes != rc->merging_rsv_size) {
2171 btrfs_end_transaction(trans, rc->extent_root);
2172 btrfs_block_rsv_release(rc->extent_root,
2173 rc->block_rsv, num_bytes);
2174 goto again;
2175 }
2176 }
2177
2178 rc->merge_reloc_tree = 1;
2179
2180 while (!list_empty(&rc->reloc_roots)) {
2181 reloc_root = list_entry(rc->reloc_roots.next,
2182 struct btrfs_root, root_list);
2183 list_del_init(&reloc_root->root_list);
2184
2185 root = read_fs_root(reloc_root->fs_info,
2186 reloc_root->root_key.offset);
2187 BUG_ON(IS_ERR(root));
2188 BUG_ON(root->reloc_root != reloc_root);
2189
2190 /*
2191 * set reference count to 1, so btrfs_recover_relocation
2192 * knows it should resumes merging
2193 */
2194 if (!err)
2195 btrfs_set_root_refs(&reloc_root->root_item, 1);
2196 btrfs_update_reloc_root(trans, root);
2197
2198 list_add(&reloc_root->root_list, &reloc_roots);
2199 }
2200
2201 list_splice(&reloc_roots, &rc->reloc_roots);
2202
2203 if (!err)
2204 btrfs_commit_transaction(trans, rc->extent_root);
2205 else
2206 btrfs_end_transaction(trans, rc->extent_root);
2207 return err;
2208 }
2209
2210 static noinline_for_stack
2211 int merge_reloc_roots(struct reloc_control *rc)
2212 {
2213 struct btrfs_root *root;
2214 struct btrfs_root *reloc_root;
2215 LIST_HEAD(reloc_roots);
2216 int found = 0;
2217 int ret;
2218 again:
2219 root = rc->extent_root;
2220
2221 /*
2222 * this serializes us with btrfs_record_root_in_transaction,
2223 * we have to make sure nobody is in the middle of
2224 * adding their roots to the list while we are
2225 * doing this splice
2226 */
2227 mutex_lock(&root->fs_info->reloc_mutex);
2228 list_splice_init(&rc->reloc_roots, &reloc_roots);
2229 mutex_unlock(&root->fs_info->reloc_mutex);
2230
2231 while (!list_empty(&reloc_roots)) {
2232 found = 1;
2233 reloc_root = list_entry(reloc_roots.next,
2234 struct btrfs_root, root_list);
2235
2236 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2237 root = read_fs_root(reloc_root->fs_info,
2238 reloc_root->root_key.offset);
2239 BUG_ON(IS_ERR(root));
2240 BUG_ON(root->reloc_root != reloc_root);
2241
2242 ret = merge_reloc_root(rc, root);
2243 BUG_ON(ret);
2244 } else {
2245 list_del_init(&reloc_root->root_list);
2246 }
2247 btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
2248 }
2249
2250 if (found) {
2251 found = 0;
2252 goto again;
2253 }
2254 BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2255 return 0;
2256 }
2257
2258 static void free_block_list(struct rb_root *blocks)
2259 {
2260 struct tree_block *block;
2261 struct rb_node *rb_node;
2262 while ((rb_node = rb_first(blocks))) {
2263 block = rb_entry(rb_node, struct tree_block, rb_node);
2264 rb_erase(rb_node, blocks);
2265 kfree(block);
2266 }
2267 }
2268
2269 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2270 struct btrfs_root *reloc_root)
2271 {
2272 struct btrfs_root *root;
2273
2274 if (reloc_root->last_trans == trans->transid)
2275 return 0;
2276
2277 root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2278 BUG_ON(IS_ERR(root));
2279 BUG_ON(root->reloc_root != reloc_root);
2280
2281 return btrfs_record_root_in_trans(trans, root);
2282 }
2283
2284 static noinline_for_stack
2285 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2286 struct reloc_control *rc,
2287 struct backref_node *node,
2288 struct backref_edge *edges[], int *nr)
2289 {
2290 struct backref_node *next;
2291 struct btrfs_root *root;
2292 int index = 0;
2293
2294 next = node;
2295 while (1) {
2296 cond_resched();
2297 next = walk_up_backref(next, edges, &index);
2298 root = next->root;
2299 BUG_ON(!root);
2300 BUG_ON(!root->ref_cows);
2301
2302 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2303 record_reloc_root_in_trans(trans, root);
2304 break;
2305 }
2306
2307 btrfs_record_root_in_trans(trans, root);
2308 root = root->reloc_root;
2309
2310 if (next->new_bytenr != root->node->start) {
2311 BUG_ON(next->new_bytenr);
2312 BUG_ON(!list_empty(&next->list));
2313 next->new_bytenr = root->node->start;
2314 next->root = root;
2315 list_add_tail(&next->list,
2316 &rc->backref_cache.changed);
2317 __mark_block_processed(rc, next);
2318 break;
2319 }
2320
2321 WARN_ON(1);
2322 root = NULL;
2323 next = walk_down_backref(edges, &index);
2324 if (!next || next->level <= node->level)
2325 break;
2326 }
2327 if (!root)
2328 return NULL;
2329
2330 *nr = index;
2331 next = node;
2332 /* setup backref node path for btrfs_reloc_cow_block */
2333 while (1) {
2334 rc->backref_cache.path[next->level] = next;
2335 if (--index < 0)
2336 break;
2337 next = edges[index]->node[UPPER];
2338 }
2339 return root;
2340 }
2341
2342 /*
2343 * select a tree root for relocation. return NULL if the block
2344 * is reference counted. we should use do_relocation() in this
2345 * case. return a tree root pointer if the block isn't reference
2346 * counted. return -ENOENT if the block is root of reloc tree.
2347 */
2348 static noinline_for_stack
2349 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2350 struct backref_node *node)
2351 {
2352 struct backref_node *next;
2353 struct btrfs_root *root;
2354 struct btrfs_root *fs_root = NULL;
2355 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2356 int index = 0;
2357
2358 next = node;
2359 while (1) {
2360 cond_resched();
2361 next = walk_up_backref(next, edges, &index);
2362 root = next->root;
2363 BUG_ON(!root);
2364
2365 /* no other choice for non-references counted tree */
2366 if (!root->ref_cows)
2367 return root;
2368
2369 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2370 fs_root = root;
2371
2372 if (next != node)
2373 return NULL;
2374
2375 next = walk_down_backref(edges, &index);
2376 if (!next || next->level <= node->level)
2377 break;
2378 }
2379
2380 if (!fs_root)
2381 return ERR_PTR(-ENOENT);
2382 return fs_root;
2383 }
2384
2385 static noinline_for_stack
2386 u64 calcu_metadata_size(struct reloc_control *rc,
2387 struct backref_node *node, int reserve)
2388 {
2389 struct backref_node *next = node;
2390 struct backref_edge *edge;
2391 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2392 u64 num_bytes = 0;
2393 int index = 0;
2394
2395 BUG_ON(reserve && node->processed);
2396
2397 while (next) {
2398 cond_resched();
2399 while (1) {
2400 if (next->processed && (reserve || next != node))
2401 break;
2402
2403 num_bytes += btrfs_level_size(rc->extent_root,
2404 next->level);
2405
2406 if (list_empty(&next->upper))
2407 break;
2408
2409 edge = list_entry(next->upper.next,
2410 struct backref_edge, list[LOWER]);
2411 edges[index++] = edge;
2412 next = edge->node[UPPER];
2413 }
2414 next = walk_down_backref(edges, &index);
2415 }
2416 return num_bytes;
2417 }
2418
2419 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2420 struct reloc_control *rc,
2421 struct backref_node *node)
2422 {
2423 struct btrfs_root *root = rc->extent_root;
2424 u64 num_bytes;
2425 int ret;
2426
2427 num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2428
2429 trans->block_rsv = rc->block_rsv;
2430 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes);
2431 if (ret) {
2432 if (ret == -EAGAIN)
2433 rc->commit_transaction = 1;
2434 return ret;
2435 }
2436
2437 return 0;
2438 }
2439
2440 static void release_metadata_space(struct reloc_control *rc,
2441 struct backref_node *node)
2442 {
2443 u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2444 btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2445 }
2446
2447 /*
2448 * relocate a block tree, and then update pointers in upper level
2449 * blocks that reference the block to point to the new location.
2450 *
2451 * if called by link_to_upper, the block has already been relocated.
2452 * in that case this function just updates pointers.
2453 */
2454 static int do_relocation(struct btrfs_trans_handle *trans,
2455 struct reloc_control *rc,
2456 struct backref_node *node,
2457 struct btrfs_key *key,
2458 struct btrfs_path *path, int lowest)
2459 {
2460 struct backref_node *upper;
2461 struct backref_edge *edge;
2462 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2463 struct btrfs_root *root;
2464 struct extent_buffer *eb;
2465 u32 blocksize;
2466 u64 bytenr;
2467 u64 generation;
2468 int nr;
2469 int slot;
2470 int ret;
2471 int err = 0;
2472
2473 BUG_ON(lowest && node->eb);
2474
2475 path->lowest_level = node->level + 1;
2476 rc->backref_cache.path[node->level] = node;
2477 list_for_each_entry(edge, &node->upper, list[LOWER]) {
2478 cond_resched();
2479
2480 upper = edge->node[UPPER];
2481 root = select_reloc_root(trans, rc, upper, edges, &nr);
2482 BUG_ON(!root);
2483
2484 if (upper->eb && !upper->locked) {
2485 if (!lowest) {
2486 ret = btrfs_bin_search(upper->eb, key,
2487 upper->level, &slot);
2488 BUG_ON(ret);
2489 bytenr = btrfs_node_blockptr(upper->eb, slot);
2490 if (node->eb->start == bytenr)
2491 goto next;
2492 }
2493 drop_node_buffer(upper);
2494 }
2495
2496 if (!upper->eb) {
2497 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2498 if (ret < 0) {
2499 err = ret;
2500 break;
2501 }
2502 BUG_ON(ret > 0);
2503
2504 if (!upper->eb) {
2505 upper->eb = path->nodes[upper->level];
2506 path->nodes[upper->level] = NULL;
2507 } else {
2508 BUG_ON(upper->eb != path->nodes[upper->level]);
2509 }
2510
2511 upper->locked = 1;
2512 path->locks[upper->level] = 0;
2513
2514 slot = path->slots[upper->level];
2515 btrfs_release_path(path);
2516 } else {
2517 ret = btrfs_bin_search(upper->eb, key, upper->level,
2518 &slot);
2519 BUG_ON(ret);
2520 }
2521
2522 bytenr = btrfs_node_blockptr(upper->eb, slot);
2523 if (lowest) {
2524 BUG_ON(bytenr != node->bytenr);
2525 } else {
2526 if (node->eb->start == bytenr)
2527 goto next;
2528 }
2529
2530 blocksize = btrfs_level_size(root, node->level);
2531 generation = btrfs_node_ptr_generation(upper->eb, slot);
2532 eb = read_tree_block(root, bytenr, blocksize, generation);
2533 if (!eb) {
2534 err = -EIO;
2535 goto next;
2536 }
2537 btrfs_tree_lock(eb);
2538 btrfs_set_lock_blocking(eb);
2539
2540 if (!node->eb) {
2541 ret = btrfs_cow_block(trans, root, eb, upper->eb,
2542 slot, &eb);
2543 btrfs_tree_unlock(eb);
2544 free_extent_buffer(eb);
2545 if (ret < 0) {
2546 err = ret;
2547 goto next;
2548 }
2549 BUG_ON(node->eb != eb);
2550 } else {
2551 btrfs_set_node_blockptr(upper->eb, slot,
2552 node->eb->start);
2553 btrfs_set_node_ptr_generation(upper->eb, slot,
2554 trans->transid);
2555 btrfs_mark_buffer_dirty(upper->eb);
2556
2557 ret = btrfs_inc_extent_ref(trans, root,
2558 node->eb->start, blocksize,
2559 upper->eb->start,
2560 btrfs_header_owner(upper->eb),
2561 node->level, 0);
2562 BUG_ON(ret);
2563
2564 ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2565 BUG_ON(ret);
2566 }
2567 next:
2568 if (!upper->pending)
2569 drop_node_buffer(upper);
2570 else
2571 unlock_node_buffer(upper);
2572 if (err)
2573 break;
2574 }
2575
2576 if (!err && node->pending) {
2577 drop_node_buffer(node);
2578 list_move_tail(&node->list, &rc->backref_cache.changed);
2579 node->pending = 0;
2580 }
2581
2582 path->lowest_level = 0;
2583 BUG_ON(err == -ENOSPC);
2584 return err;
2585 }
2586
2587 static int link_to_upper(struct btrfs_trans_handle *trans,
2588 struct reloc_control *rc,
2589 struct backref_node *node,
2590 struct btrfs_path *path)
2591 {
2592 struct btrfs_key key;
2593
2594 btrfs_node_key_to_cpu(node->eb, &key, 0);
2595 return do_relocation(trans, rc, node, &key, path, 0);
2596 }
2597
2598 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2599 struct reloc_control *rc,
2600 struct btrfs_path *path, int err)
2601 {
2602 LIST_HEAD(list);
2603 struct backref_cache *cache = &rc->backref_cache;
2604 struct backref_node *node;
2605 int level;
2606 int ret;
2607
2608 for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2609 while (!list_empty(&cache->pending[level])) {
2610 node = list_entry(cache->pending[level].next,
2611 struct backref_node, list);
2612 list_move_tail(&node->list, &list);
2613 BUG_ON(!node->pending);
2614
2615 if (!err) {
2616 ret = link_to_upper(trans, rc, node, path);
2617 if (ret < 0)
2618 err = ret;
2619 }
2620 }
2621 list_splice_init(&list, &cache->pending[level]);
2622 }
2623 return err;
2624 }
2625
2626 static void mark_block_processed(struct reloc_control *rc,
2627 u64 bytenr, u32 blocksize)
2628 {
2629 set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2630 EXTENT_DIRTY, GFP_NOFS);
2631 }
2632
2633 static void __mark_block_processed(struct reloc_control *rc,
2634 struct backref_node *node)
2635 {
2636 u32 blocksize;
2637 if (node->level == 0 ||
2638 in_block_group(node->bytenr, rc->block_group)) {
2639 blocksize = btrfs_level_size(rc->extent_root, node->level);
2640 mark_block_processed(rc, node->bytenr, blocksize);
2641 }
2642 node->processed = 1;
2643 }
2644
2645 /*
2646 * mark a block and all blocks directly/indirectly reference the block
2647 * as processed.
2648 */
2649 static void update_processed_blocks(struct reloc_control *rc,
2650 struct backref_node *node)
2651 {
2652 struct backref_node *next = node;
2653 struct backref_edge *edge;
2654 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2655 int index = 0;
2656
2657 while (next) {
2658 cond_resched();
2659 while (1) {
2660 if (next->processed)
2661 break;
2662
2663 __mark_block_processed(rc, next);
2664
2665 if (list_empty(&next->upper))
2666 break;
2667
2668 edge = list_entry(next->upper.next,
2669 struct backref_edge, list[LOWER]);
2670 edges[index++] = edge;
2671 next = edge->node[UPPER];
2672 }
2673 next = walk_down_backref(edges, &index);
2674 }
2675 }
2676
2677 static int tree_block_processed(u64 bytenr, u32 blocksize,
2678 struct reloc_control *rc)
2679 {
2680 if (test_range_bit(&rc->processed_blocks, bytenr,
2681 bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2682 return 1;
2683 return 0;
2684 }
2685
2686 static int get_tree_block_key(struct reloc_control *rc,
2687 struct tree_block *block)
2688 {
2689 struct extent_buffer *eb;
2690
2691 BUG_ON(block->key_ready);
2692 eb = read_tree_block(rc->extent_root, block->bytenr,
2693 block->key.objectid, block->key.offset);
2694 BUG_ON(!eb);
2695 WARN_ON(btrfs_header_level(eb) != block->level);
2696 if (block->level == 0)
2697 btrfs_item_key_to_cpu(eb, &block->key, 0);
2698 else
2699 btrfs_node_key_to_cpu(eb, &block->key, 0);
2700 free_extent_buffer(eb);
2701 block->key_ready = 1;
2702 return 0;
2703 }
2704
2705 static int reada_tree_block(struct reloc_control *rc,
2706 struct tree_block *block)
2707 {
2708 BUG_ON(block->key_ready);
2709 readahead_tree_block(rc->extent_root, block->bytenr,
2710 block->key.objectid, block->key.offset);
2711 return 0;
2712 }
2713
2714 /*
2715 * helper function to relocate a tree block
2716 */
2717 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2718 struct reloc_control *rc,
2719 struct backref_node *node,
2720 struct btrfs_key *key,
2721 struct btrfs_path *path)
2722 {
2723 struct btrfs_root *root;
2724 int release = 0;
2725 int ret = 0;
2726
2727 if (!node)
2728 return 0;
2729
2730 BUG_ON(node->processed);
2731 root = select_one_root(trans, node);
2732 if (root == ERR_PTR(-ENOENT)) {
2733 update_processed_blocks(rc, node);
2734 goto out;
2735 }
2736
2737 if (!root || root->ref_cows) {
2738 ret = reserve_metadata_space(trans, rc, node);
2739 if (ret)
2740 goto out;
2741 release = 1;
2742 }
2743
2744 if (root) {
2745 if (root->ref_cows) {
2746 BUG_ON(node->new_bytenr);
2747 BUG_ON(!list_empty(&node->list));
2748 btrfs_record_root_in_trans(trans, root);
2749 root = root->reloc_root;
2750 node->new_bytenr = root->node->start;
2751 node->root = root;
2752 list_add_tail(&node->list, &rc->backref_cache.changed);
2753 } else {
2754 path->lowest_level = node->level;
2755 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2756 btrfs_release_path(path);
2757 if (ret > 0)
2758 ret = 0;
2759 }
2760 if (!ret)
2761 update_processed_blocks(rc, node);
2762 } else {
2763 ret = do_relocation(trans, rc, node, key, path, 1);
2764 }
2765 out:
2766 if (ret || node->level == 0 || node->cowonly) {
2767 if (release)
2768 release_metadata_space(rc, node);
2769 remove_backref_node(&rc->backref_cache, node);
2770 }
2771 return ret;
2772 }
2773
2774 /*
2775 * relocate a list of blocks
2776 */
2777 static noinline_for_stack
2778 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2779 struct reloc_control *rc, struct rb_root *blocks)
2780 {
2781 struct backref_node *node;
2782 struct btrfs_path *path;
2783 struct tree_block *block;
2784 struct rb_node *rb_node;
2785 int ret;
2786 int err = 0;
2787
2788 path = btrfs_alloc_path();
2789 if (!path)
2790 return -ENOMEM;
2791
2792 rb_node = rb_first(blocks);
2793 while (rb_node) {
2794 block = rb_entry(rb_node, struct tree_block, rb_node);
2795 if (!block->key_ready)
2796 reada_tree_block(rc, block);
2797 rb_node = rb_next(rb_node);
2798 }
2799
2800 rb_node = rb_first(blocks);
2801 while (rb_node) {
2802 block = rb_entry(rb_node, struct tree_block, rb_node);
2803 if (!block->key_ready)
2804 get_tree_block_key(rc, block);
2805 rb_node = rb_next(rb_node);
2806 }
2807
2808 rb_node = rb_first(blocks);
2809 while (rb_node) {
2810 block = rb_entry(rb_node, struct tree_block, rb_node);
2811
2812 node = build_backref_tree(rc, &block->key,
2813 block->level, block->bytenr);
2814 if (IS_ERR(node)) {
2815 err = PTR_ERR(node);
2816 goto out;
2817 }
2818
2819 ret = relocate_tree_block(trans, rc, node, &block->key,
2820 path);
2821 if (ret < 0) {
2822 if (ret != -EAGAIN || rb_node == rb_first(blocks))
2823 err = ret;
2824 goto out;
2825 }
2826 rb_node = rb_next(rb_node);
2827 }
2828 out:
2829 free_block_list(blocks);
2830 err = finish_pending_nodes(trans, rc, path, err);
2831
2832 btrfs_free_path(path);
2833 return err;
2834 }
2835
2836 static noinline_for_stack
2837 int prealloc_file_extent_cluster(struct inode *inode,
2838 struct file_extent_cluster *cluster)
2839 {
2840 u64 alloc_hint = 0;
2841 u64 start;
2842 u64 end;
2843 u64 offset = BTRFS_I(inode)->index_cnt;
2844 u64 num_bytes;
2845 int nr = 0;
2846 int ret = 0;
2847
2848 BUG_ON(cluster->start != cluster->boundary[0]);
2849 mutex_lock(&inode->i_mutex);
2850
2851 ret = btrfs_check_data_free_space(inode, cluster->end +
2852 1 - cluster->start);
2853 if (ret)
2854 goto out;
2855
2856 while (nr < cluster->nr) {
2857 start = cluster->boundary[nr] - offset;
2858 if (nr + 1 < cluster->nr)
2859 end = cluster->boundary[nr + 1] - 1 - offset;
2860 else
2861 end = cluster->end - offset;
2862
2863 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2864 num_bytes = end + 1 - start;
2865 ret = btrfs_prealloc_file_range(inode, 0, start,
2866 num_bytes, num_bytes,
2867 end + 1, &alloc_hint);
2868 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2869 if (ret)
2870 break;
2871 nr++;
2872 }
2873 btrfs_free_reserved_data_space(inode, cluster->end +
2874 1 - cluster->start);
2875 out:
2876 mutex_unlock(&inode->i_mutex);
2877 return ret;
2878 }
2879
2880 static noinline_for_stack
2881 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
2882 u64 block_start)
2883 {
2884 struct btrfs_root *root = BTRFS_I(inode)->root;
2885 struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2886 struct extent_map *em;
2887 int ret = 0;
2888
2889 em = alloc_extent_map();
2890 if (!em)
2891 return -ENOMEM;
2892
2893 em->start = start;
2894 em->len = end + 1 - start;
2895 em->block_len = em->len;
2896 em->block_start = block_start;
2897 em->bdev = root->fs_info->fs_devices->latest_bdev;
2898 set_bit(EXTENT_FLAG_PINNED, &em->flags);
2899
2900 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2901 while (1) {
2902 write_lock(&em_tree->lock);
2903 ret = add_extent_mapping(em_tree, em);
2904 write_unlock(&em_tree->lock);
2905 if (ret != -EEXIST) {
2906 free_extent_map(em);
2907 break;
2908 }
2909 btrfs_drop_extent_cache(inode, start, end, 0);
2910 }
2911 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2912 return ret;
2913 }
2914
2915 static int relocate_file_extent_cluster(struct inode *inode,
2916 struct file_extent_cluster *cluster)
2917 {
2918 u64 page_start;
2919 u64 page_end;
2920 u64 offset = BTRFS_I(inode)->index_cnt;
2921 unsigned long index;
2922 unsigned long last_index;
2923 struct page *page;
2924 struct file_ra_state *ra;
2925 gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
2926 int nr = 0;
2927 int ret = 0;
2928
2929 if (!cluster->nr)
2930 return 0;
2931
2932 ra = kzalloc(sizeof(*ra), GFP_NOFS);
2933 if (!ra)
2934 return -ENOMEM;
2935
2936 ret = prealloc_file_extent_cluster(inode, cluster);
2937 if (ret)
2938 goto out;
2939
2940 file_ra_state_init(ra, inode->i_mapping);
2941
2942 ret = setup_extent_mapping(inode, cluster->start - offset,
2943 cluster->end - offset, cluster->start);
2944 if (ret)
2945 goto out;
2946
2947 index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
2948 last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
2949 while (index <= last_index) {
2950 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
2951 if (ret)
2952 goto out;
2953
2954 page = find_lock_page(inode->i_mapping, index);
2955 if (!page) {
2956 page_cache_sync_readahead(inode->i_mapping,
2957 ra, NULL, index,
2958 last_index + 1 - index);
2959 page = find_or_create_page(inode->i_mapping, index,
2960 mask);
2961 if (!page) {
2962 btrfs_delalloc_release_metadata(inode,
2963 PAGE_CACHE_SIZE);
2964 ret = -ENOMEM;
2965 goto out;
2966 }
2967 }
2968
2969 if (PageReadahead(page)) {
2970 page_cache_async_readahead(inode->i_mapping,
2971 ra, NULL, page, index,
2972 last_index + 1 - index);
2973 }
2974
2975 if (!PageUptodate(page)) {
2976 btrfs_readpage(NULL, page);
2977 lock_page(page);
2978 if (!PageUptodate(page)) {
2979 unlock_page(page);
2980 page_cache_release(page);
2981 btrfs_delalloc_release_metadata(inode,
2982 PAGE_CACHE_SIZE);
2983 ret = -EIO;
2984 goto out;
2985 }
2986 }
2987
2988 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2989 page_end = page_start + PAGE_CACHE_SIZE - 1;
2990
2991 lock_extent(&BTRFS_I(inode)->io_tree,
2992 page_start, page_end, GFP_NOFS);
2993
2994 set_page_extent_mapped(page);
2995
2996 if (nr < cluster->nr &&
2997 page_start + offset == cluster->boundary[nr]) {
2998 set_extent_bits(&BTRFS_I(inode)->io_tree,
2999 page_start, page_end,
3000 EXTENT_BOUNDARY, GFP_NOFS);
3001 nr++;
3002 }
3003
3004 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3005 set_page_dirty(page);
3006
3007 unlock_extent(&BTRFS_I(inode)->io_tree,
3008 page_start, page_end, GFP_NOFS);
3009 unlock_page(page);
3010 page_cache_release(page);
3011
3012 index++;
3013 balance_dirty_pages_ratelimited(inode->i_mapping);
3014 btrfs_throttle(BTRFS_I(inode)->root);
3015 }
3016 WARN_ON(nr != cluster->nr);
3017 out:
3018 kfree(ra);
3019 return ret;
3020 }
3021
3022 static noinline_for_stack
3023 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3024 struct file_extent_cluster *cluster)
3025 {
3026 int ret;
3027
3028 if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3029 ret = relocate_file_extent_cluster(inode, cluster);
3030 if (ret)
3031 return ret;
3032 cluster->nr = 0;
3033 }
3034
3035 if (!cluster->nr)
3036 cluster->start = extent_key->objectid;
3037 else
3038 BUG_ON(cluster->nr >= MAX_EXTENTS);
3039 cluster->end = extent_key->objectid + extent_key->offset - 1;
3040 cluster->boundary[cluster->nr] = extent_key->objectid;
3041 cluster->nr++;
3042
3043 if (cluster->nr >= MAX_EXTENTS) {
3044 ret = relocate_file_extent_cluster(inode, cluster);
3045 if (ret)
3046 return ret;
3047 cluster->nr = 0;
3048 }
3049 return 0;
3050 }
3051
3052 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3053 static int get_ref_objectid_v0(struct reloc_control *rc,
3054 struct btrfs_path *path,
3055 struct btrfs_key *extent_key,
3056 u64 *ref_objectid, int *path_change)
3057 {
3058 struct btrfs_key key;
3059 struct extent_buffer *leaf;
3060 struct btrfs_extent_ref_v0 *ref0;
3061 int ret;
3062 int slot;
3063
3064 leaf = path->nodes[0];
3065 slot = path->slots[0];
3066 while (1) {
3067 if (slot >= btrfs_header_nritems(leaf)) {
3068 ret = btrfs_next_leaf(rc->extent_root, path);
3069 if (ret < 0)
3070 return ret;
3071 BUG_ON(ret > 0);
3072 leaf = path->nodes[0];
3073 slot = path->slots[0];
3074 if (path_change)
3075 *path_change = 1;
3076 }
3077 btrfs_item_key_to_cpu(leaf, &key, slot);
3078 if (key.objectid != extent_key->objectid)
3079 return -ENOENT;
3080
3081 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3082 slot++;
3083 continue;
3084 }
3085 ref0 = btrfs_item_ptr(leaf, slot,
3086 struct btrfs_extent_ref_v0);
3087 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3088 break;
3089 }
3090 return 0;
3091 }
3092 #endif
3093
3094 /*
3095 * helper to add a tree block to the list.
3096 * the major work is getting the generation and level of the block
3097 */
3098 static int add_tree_block(struct reloc_control *rc,
3099 struct btrfs_key *extent_key,
3100 struct btrfs_path *path,
3101 struct rb_root *blocks)
3102 {
3103 struct extent_buffer *eb;
3104 struct btrfs_extent_item *ei;
3105 struct btrfs_tree_block_info *bi;
3106 struct tree_block *block;
3107 struct rb_node *rb_node;
3108 u32 item_size;
3109 int level = -1;
3110 int generation;
3111
3112 eb = path->nodes[0];
3113 item_size = btrfs_item_size_nr(eb, path->slots[0]);
3114
3115 if (item_size >= sizeof(*ei) + sizeof(*bi)) {
3116 ei = btrfs_item_ptr(eb, path->slots[0],
3117 struct btrfs_extent_item);
3118 bi = (struct btrfs_tree_block_info *)(ei + 1);
3119 generation = btrfs_extent_generation(eb, ei);
3120 level = btrfs_tree_block_level(eb, bi);
3121 } else {
3122 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3123 u64 ref_owner;
3124 int ret;
3125
3126 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3127 ret = get_ref_objectid_v0(rc, path, extent_key,
3128 &ref_owner, NULL);
3129 if (ret < 0)
3130 return ret;
3131 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3132 level = (int)ref_owner;
3133 /* FIXME: get real generation */
3134 generation = 0;
3135 #else
3136 BUG();
3137 #endif
3138 }
3139
3140 btrfs_release_path(path);
3141
3142 BUG_ON(level == -1);
3143
3144 block = kmalloc(sizeof(*block), GFP_NOFS);
3145 if (!block)
3146 return -ENOMEM;
3147
3148 block->bytenr = extent_key->objectid;
3149 block->key.objectid = extent_key->offset;
3150 block->key.offset = generation;
3151 block->level = level;
3152 block->key_ready = 0;
3153
3154 rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3155 BUG_ON(rb_node);
3156
3157 return 0;
3158 }
3159
3160 /*
3161 * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3162 */
3163 static int __add_tree_block(struct reloc_control *rc,
3164 u64 bytenr, u32 blocksize,
3165 struct rb_root *blocks)
3166 {
3167 struct btrfs_path *path;
3168 struct btrfs_key key;
3169 int ret;
3170
3171 if (tree_block_processed(bytenr, blocksize, rc))
3172 return 0;
3173
3174 if (tree_search(blocks, bytenr))
3175 return 0;
3176
3177 path = btrfs_alloc_path();
3178 if (!path)
3179 return -ENOMEM;
3180
3181 key.objectid = bytenr;
3182 key.type = BTRFS_EXTENT_ITEM_KEY;
3183 key.offset = blocksize;
3184
3185 path->search_commit_root = 1;
3186 path->skip_locking = 1;
3187 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3188 if (ret < 0)
3189 goto out;
3190 BUG_ON(ret);
3191
3192 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3193 ret = add_tree_block(rc, &key, path, blocks);
3194 out:
3195 btrfs_free_path(path);
3196 return ret;
3197 }
3198
3199 /*
3200 * helper to check if the block use full backrefs for pointers in it
3201 */
3202 static int block_use_full_backref(struct reloc_control *rc,
3203 struct extent_buffer *eb)
3204 {
3205 u64 flags;
3206 int ret;
3207
3208 if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3209 btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3210 return 1;
3211
3212 ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3213 eb->start, eb->len, NULL, &flags);
3214 BUG_ON(ret);
3215
3216 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3217 ret = 1;
3218 else
3219 ret = 0;
3220 return ret;
3221 }
3222
3223 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3224 struct inode *inode, u64 ino)
3225 {
3226 struct btrfs_key key;
3227 struct btrfs_path *path;
3228 struct btrfs_root *root = fs_info->tree_root;
3229 struct btrfs_trans_handle *trans;
3230 unsigned long nr;
3231 int ret = 0;
3232
3233 if (inode)
3234 goto truncate;
3235
3236 key.objectid = ino;
3237 key.type = BTRFS_INODE_ITEM_KEY;
3238 key.offset = 0;
3239
3240 inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3241 if (IS_ERR_OR_NULL(inode) || is_bad_inode(inode)) {
3242 if (inode && !IS_ERR(inode))
3243 iput(inode);
3244 return -ENOENT;
3245 }
3246
3247 truncate:
3248 path = btrfs_alloc_path();
3249 if (!path) {
3250 ret = -ENOMEM;
3251 goto out;
3252 }
3253
3254 trans = btrfs_join_transaction(root);
3255 if (IS_ERR(trans)) {
3256 btrfs_free_path(path);
3257 ret = PTR_ERR(trans);
3258 goto out;
3259 }
3260
3261 ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
3262
3263 btrfs_free_path(path);
3264 nr = trans->blocks_used;
3265 btrfs_end_transaction(trans, root);
3266 btrfs_btree_balance_dirty(root, nr);
3267 out:
3268 iput(inode);
3269 return ret;
3270 }
3271
3272 /*
3273 * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3274 * this function scans fs tree to find blocks reference the data extent
3275 */
3276 static int find_data_references(struct reloc_control *rc,
3277 struct btrfs_key *extent_key,
3278 struct extent_buffer *leaf,
3279 struct btrfs_extent_data_ref *ref,
3280 struct rb_root *blocks)
3281 {
3282 struct btrfs_path *path;
3283 struct tree_block *block;
3284 struct btrfs_root *root;
3285 struct btrfs_file_extent_item *fi;
3286 struct rb_node *rb_node;
3287 struct btrfs_key key;
3288 u64 ref_root;
3289 u64 ref_objectid;
3290 u64 ref_offset;
3291 u32 ref_count;
3292 u32 nritems;
3293 int err = 0;
3294 int added = 0;
3295 int counted;
3296 int ret;
3297
3298 ref_root = btrfs_extent_data_ref_root(leaf, ref);
3299 ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3300 ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3301 ref_count = btrfs_extent_data_ref_count(leaf, ref);
3302
3303 /*
3304 * This is an extent belonging to the free space cache, lets just delete
3305 * it and redo the search.
3306 */
3307 if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3308 ret = delete_block_group_cache(rc->extent_root->fs_info,
3309 NULL, ref_objectid);
3310 if (ret != -ENOENT)
3311 return ret;
3312 ret = 0;
3313 }
3314
3315 path = btrfs_alloc_path();
3316 if (!path)
3317 return -ENOMEM;
3318 path->reada = 1;
3319
3320 root = read_fs_root(rc->extent_root->fs_info, ref_root);
3321 if (IS_ERR(root)) {
3322 err = PTR_ERR(root);
3323 goto out;
3324 }
3325
3326 key.objectid = ref_objectid;
3327 key.type = BTRFS_EXTENT_DATA_KEY;
3328 if (ref_offset > ((u64)-1 << 32))
3329 key.offset = 0;
3330 else
3331 key.offset = ref_offset;
3332
3333 path->search_commit_root = 1;
3334 path->skip_locking = 1;
3335 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3336 if (ret < 0) {
3337 err = ret;
3338 goto out;
3339 }
3340
3341 leaf = path->nodes[0];
3342 nritems = btrfs_header_nritems(leaf);
3343 /*
3344 * the references in tree blocks that use full backrefs
3345 * are not counted in
3346 */
3347 if (block_use_full_backref(rc, leaf))
3348 counted = 0;
3349 else
3350 counted = 1;
3351 rb_node = tree_search(blocks, leaf->start);
3352 if (rb_node) {
3353 if (counted)
3354 added = 1;
3355 else
3356 path->slots[0] = nritems;
3357 }
3358
3359 while (ref_count > 0) {
3360 while (path->slots[0] >= nritems) {
3361 ret = btrfs_next_leaf(root, path);
3362 if (ret < 0) {
3363 err = ret;
3364 goto out;
3365 }
3366 if (ret > 0) {
3367 WARN_ON(1);
3368 goto out;
3369 }
3370
3371 leaf = path->nodes[0];
3372 nritems = btrfs_header_nritems(leaf);
3373 added = 0;
3374
3375 if (block_use_full_backref(rc, leaf))
3376 counted = 0;
3377 else
3378 counted = 1;
3379 rb_node = tree_search(blocks, leaf->start);
3380 if (rb_node) {
3381 if (counted)
3382 added = 1;
3383 else
3384 path->slots[0] = nritems;
3385 }
3386 }
3387
3388 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3389 if (key.objectid != ref_objectid ||
3390 key.type != BTRFS_EXTENT_DATA_KEY) {
3391 WARN_ON(1);
3392 break;
3393 }
3394
3395 fi = btrfs_item_ptr(leaf, path->slots[0],
3396 struct btrfs_file_extent_item);
3397
3398 if (btrfs_file_extent_type(leaf, fi) ==
3399 BTRFS_FILE_EXTENT_INLINE)
3400 goto next;
3401
3402 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3403 extent_key->objectid)
3404 goto next;
3405
3406 key.offset -= btrfs_file_extent_offset(leaf, fi);
3407 if (key.offset != ref_offset)
3408 goto next;
3409
3410 if (counted)
3411 ref_count--;
3412 if (added)
3413 goto next;
3414
3415 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3416 block = kmalloc(sizeof(*block), GFP_NOFS);
3417 if (!block) {
3418 err = -ENOMEM;
3419 break;
3420 }
3421 block->bytenr = leaf->start;
3422 btrfs_item_key_to_cpu(leaf, &block->key, 0);
3423 block->level = 0;
3424 block->key_ready = 1;
3425 rb_node = tree_insert(blocks, block->bytenr,
3426 &block->rb_node);
3427 BUG_ON(rb_node);
3428 }
3429 if (counted)
3430 added = 1;
3431 else
3432 path->slots[0] = nritems;
3433 next:
3434 path->slots[0]++;
3435
3436 }
3437 out:
3438 btrfs_free_path(path);
3439 return err;
3440 }
3441
3442 /*
3443 * hepler to find all tree blocks that reference a given data extent
3444 */
3445 static noinline_for_stack
3446 int add_data_references(struct reloc_control *rc,
3447 struct btrfs_key *extent_key,
3448 struct btrfs_path *path,
3449 struct rb_root *blocks)
3450 {
3451 struct btrfs_key key;
3452 struct extent_buffer *eb;
3453 struct btrfs_extent_data_ref *dref;
3454 struct btrfs_extent_inline_ref *iref;
3455 unsigned long ptr;
3456 unsigned long end;
3457 u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3458 int ret;
3459 int err = 0;
3460
3461 eb = path->nodes[0];
3462 ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3463 end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3464 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3465 if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3466 ptr = end;
3467 else
3468 #endif
3469 ptr += sizeof(struct btrfs_extent_item);
3470
3471 while (ptr < end) {
3472 iref = (struct btrfs_extent_inline_ref *)ptr;
3473 key.type = btrfs_extent_inline_ref_type(eb, iref);
3474 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3475 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3476 ret = __add_tree_block(rc, key.offset, blocksize,
3477 blocks);
3478 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3479 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3480 ret = find_data_references(rc, extent_key,
3481 eb, dref, blocks);
3482 } else {
3483 BUG();
3484 }
3485 ptr += btrfs_extent_inline_ref_size(key.type);
3486 }
3487 WARN_ON(ptr > end);
3488
3489 while (1) {
3490 cond_resched();
3491 eb = path->nodes[0];
3492 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3493 ret = btrfs_next_leaf(rc->extent_root, path);
3494 if (ret < 0) {
3495 err = ret;
3496 break;
3497 }
3498 if (ret > 0)
3499 break;
3500 eb = path->nodes[0];
3501 }
3502
3503 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3504 if (key.objectid != extent_key->objectid)
3505 break;
3506
3507 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3508 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3509 key.type == BTRFS_EXTENT_REF_V0_KEY) {
3510 #else
3511 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3512 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3513 #endif
3514 ret = __add_tree_block(rc, key.offset, blocksize,
3515 blocks);
3516 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3517 dref = btrfs_item_ptr(eb, path->slots[0],
3518 struct btrfs_extent_data_ref);
3519 ret = find_data_references(rc, extent_key,
3520 eb, dref, blocks);
3521 } else {
3522 ret = 0;
3523 }
3524 if (ret) {
3525 err = ret;
3526 break;
3527 }
3528 path->slots[0]++;
3529 }
3530 btrfs_release_path(path);
3531 if (err)
3532 free_block_list(blocks);
3533 return err;
3534 }
3535
3536 /*
3537 * hepler to find next unprocessed extent
3538 */
3539 static noinline_for_stack
3540 int find_next_extent(struct btrfs_trans_handle *trans,
3541 struct reloc_control *rc, struct btrfs_path *path,
3542 struct btrfs_key *extent_key)
3543 {
3544 struct btrfs_key key;
3545 struct extent_buffer *leaf;
3546 u64 start, end, last;
3547 int ret;
3548
3549 last = rc->block_group->key.objectid + rc->block_group->key.offset;
3550 while (1) {
3551 cond_resched();
3552 if (rc->search_start >= last) {
3553 ret = 1;
3554 break;
3555 }
3556
3557 key.objectid = rc->search_start;
3558 key.type = BTRFS_EXTENT_ITEM_KEY;
3559 key.offset = 0;
3560
3561 path->search_commit_root = 1;
3562 path->skip_locking = 1;
3563 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3564 0, 0);
3565 if (ret < 0)
3566 break;
3567 next:
3568 leaf = path->nodes[0];
3569 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3570 ret = btrfs_next_leaf(rc->extent_root, path);
3571 if (ret != 0)
3572 break;
3573 leaf = path->nodes[0];
3574 }
3575
3576 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3577 if (key.objectid >= last) {
3578 ret = 1;
3579 break;
3580 }
3581
3582 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3583 key.objectid + key.offset <= rc->search_start) {
3584 path->slots[0]++;
3585 goto next;
3586 }
3587
3588 ret = find_first_extent_bit(&rc->processed_blocks,
3589 key.objectid, &start, &end,
3590 EXTENT_DIRTY);
3591
3592 if (ret == 0 && start <= key.objectid) {
3593 btrfs_release_path(path);
3594 rc->search_start = end + 1;
3595 } else {
3596 rc->search_start = key.objectid + key.offset;
3597 memcpy(extent_key, &key, sizeof(key));
3598 return 0;
3599 }
3600 }
3601 btrfs_release_path(path);
3602 return ret;
3603 }
3604
3605 static void set_reloc_control(struct reloc_control *rc)
3606 {
3607 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3608
3609 mutex_lock(&fs_info->reloc_mutex);
3610 fs_info->reloc_ctl = rc;
3611 mutex_unlock(&fs_info->reloc_mutex);
3612 }
3613
3614 static void unset_reloc_control(struct reloc_control *rc)
3615 {
3616 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3617
3618 mutex_lock(&fs_info->reloc_mutex);
3619 fs_info->reloc_ctl = NULL;
3620 mutex_unlock(&fs_info->reloc_mutex);
3621 }
3622
3623 static int check_extent_flags(u64 flags)
3624 {
3625 if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3626 (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3627 return 1;
3628 if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3629 !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3630 return 1;
3631 if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3632 (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3633 return 1;
3634 return 0;
3635 }
3636
3637 static noinline_for_stack
3638 int prepare_to_relocate(struct reloc_control *rc)
3639 {
3640 struct btrfs_trans_handle *trans;
3641 int ret;
3642
3643 rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root);
3644 if (!rc->block_rsv)
3645 return -ENOMEM;
3646
3647 /*
3648 * reserve some space for creating reloc trees.
3649 * btrfs_init_reloc_root will use them when there
3650 * is no reservation in transaction handle.
3651 */
3652 ret = btrfs_block_rsv_add(rc->extent_root, rc->block_rsv,
3653 rc->extent_root->nodesize * 256);
3654 if (ret)
3655 return ret;
3656
3657 memset(&rc->cluster, 0, sizeof(rc->cluster));
3658 rc->search_start = rc->block_group->key.objectid;
3659 rc->extents_found = 0;
3660 rc->nodes_relocated = 0;
3661 rc->merging_rsv_size = 0;
3662
3663 rc->create_reloc_tree = 1;
3664 set_reloc_control(rc);
3665
3666 trans = btrfs_join_transaction(rc->extent_root);
3667 BUG_ON(IS_ERR(trans));
3668 btrfs_commit_transaction(trans, rc->extent_root);
3669 return 0;
3670 }
3671
3672 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3673 {
3674 struct rb_root blocks = RB_ROOT;
3675 struct btrfs_key key;
3676 struct btrfs_trans_handle *trans = NULL;
3677 struct btrfs_path *path;
3678 struct btrfs_extent_item *ei;
3679 unsigned long nr;
3680 u64 flags;
3681 u32 item_size;
3682 int ret;
3683 int err = 0;
3684 int progress = 0;
3685
3686 path = btrfs_alloc_path();
3687 if (!path)
3688 return -ENOMEM;
3689 path->reada = 1;
3690
3691 ret = prepare_to_relocate(rc);
3692 if (ret) {
3693 err = ret;
3694 goto out_free;
3695 }
3696
3697 while (1) {
3698 progress++;
3699 trans = btrfs_start_transaction(rc->extent_root, 0);
3700 BUG_ON(IS_ERR(trans));
3701 restart:
3702 if (update_backref_cache(trans, &rc->backref_cache)) {
3703 btrfs_end_transaction(trans, rc->extent_root);
3704 continue;
3705 }
3706
3707 ret = find_next_extent(trans, rc, path, &key);
3708 if (ret < 0)
3709 err = ret;
3710 if (ret != 0)
3711 break;
3712
3713 rc->extents_found++;
3714
3715 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3716 struct btrfs_extent_item);
3717 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3718 if (item_size >= sizeof(*ei)) {
3719 flags = btrfs_extent_flags(path->nodes[0], ei);
3720 ret = check_extent_flags(flags);
3721 BUG_ON(ret);
3722
3723 } else {
3724 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3725 u64 ref_owner;
3726 int path_change = 0;
3727
3728 BUG_ON(item_size !=
3729 sizeof(struct btrfs_extent_item_v0));
3730 ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3731 &path_change);
3732 if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3733 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3734 else
3735 flags = BTRFS_EXTENT_FLAG_DATA;
3736
3737 if (path_change) {
3738 btrfs_release_path(path);
3739
3740 path->search_commit_root = 1;
3741 path->skip_locking = 1;
3742 ret = btrfs_search_slot(NULL, rc->extent_root,
3743 &key, path, 0, 0);
3744 if (ret < 0) {
3745 err = ret;
3746 break;
3747 }
3748 BUG_ON(ret > 0);
3749 }
3750 #else
3751 BUG();
3752 #endif
3753 }
3754
3755 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3756 ret = add_tree_block(rc, &key, path, &blocks);
3757 } else if (rc->stage == UPDATE_DATA_PTRS &&
3758 (flags & BTRFS_EXTENT_FLAG_DATA)) {
3759 ret = add_data_references(rc, &key, path, &blocks);
3760 } else {
3761 btrfs_release_path(path);
3762 ret = 0;
3763 }
3764 if (ret < 0) {
3765 err = ret;
3766 break;
3767 }
3768
3769 if (!RB_EMPTY_ROOT(&blocks)) {
3770 ret = relocate_tree_blocks(trans, rc, &blocks);
3771 if (ret < 0) {
3772 if (ret != -EAGAIN) {
3773 err = ret;
3774 break;
3775 }
3776 rc->extents_found--;
3777 rc->search_start = key.objectid;
3778 }
3779 }
3780
3781 ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 5);
3782 if (ret < 0) {
3783 if (ret != -EAGAIN) {
3784 err = ret;
3785 WARN_ON(1);
3786 break;
3787 }
3788 rc->commit_transaction = 1;
3789 }
3790
3791 if (rc->commit_transaction) {
3792 rc->commit_transaction = 0;
3793 ret = btrfs_commit_transaction(trans, rc->extent_root);
3794 BUG_ON(ret);
3795 } else {
3796 nr = trans->blocks_used;
3797 btrfs_end_transaction_throttle(trans, rc->extent_root);
3798 btrfs_btree_balance_dirty(rc->extent_root, nr);
3799 }
3800 trans = NULL;
3801
3802 if (rc->stage == MOVE_DATA_EXTENTS &&
3803 (flags & BTRFS_EXTENT_FLAG_DATA)) {
3804 rc->found_file_extent = 1;
3805 ret = relocate_data_extent(rc->data_inode,
3806 &key, &rc->cluster);
3807 if (ret < 0) {
3808 err = ret;
3809 break;
3810 }
3811 }
3812 }
3813 if (trans && progress && err == -ENOSPC) {
3814 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
3815 rc->block_group->flags);
3816 if (ret == 0) {
3817 err = 0;
3818 progress = 0;
3819 goto restart;
3820 }
3821 }
3822
3823 btrfs_release_path(path);
3824 clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3825 GFP_NOFS);
3826
3827 if (trans) {
3828 nr = trans->blocks_used;
3829 btrfs_end_transaction_throttle(trans, rc->extent_root);
3830 btrfs_btree_balance_dirty(rc->extent_root, nr);
3831 }
3832
3833 if (!err) {
3834 ret = relocate_file_extent_cluster(rc->data_inode,
3835 &rc->cluster);
3836 if (ret < 0)
3837 err = ret;
3838 }
3839
3840 rc->create_reloc_tree = 0;
3841 set_reloc_control(rc);
3842
3843 backref_cache_cleanup(&rc->backref_cache);
3844 btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3845
3846 err = prepare_to_merge(rc, err);
3847
3848 merge_reloc_roots(rc);
3849
3850 rc->merge_reloc_tree = 0;
3851 unset_reloc_control(rc);
3852 btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3853
3854 /* get rid of pinned extents */
3855 trans = btrfs_join_transaction(rc->extent_root);
3856 if (IS_ERR(trans))
3857 err = PTR_ERR(trans);
3858 else
3859 btrfs_commit_transaction(trans, rc->extent_root);
3860 out_free:
3861 btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
3862 btrfs_free_path(path);
3863 return err;
3864 }
3865
3866 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3867 struct btrfs_root *root, u64 objectid)
3868 {
3869 struct btrfs_path *path;
3870 struct btrfs_inode_item *item;
3871 struct extent_buffer *leaf;
3872 int ret;
3873
3874 path = btrfs_alloc_path();
3875 if (!path)
3876 return -ENOMEM;
3877
3878 ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3879 if (ret)
3880 goto out;
3881
3882 leaf = path->nodes[0];
3883 item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3884 memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3885 btrfs_set_inode_generation(leaf, item, 1);
3886 btrfs_set_inode_size(leaf, item, 0);
3887 btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3888 btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
3889 BTRFS_INODE_PREALLOC);
3890 btrfs_mark_buffer_dirty(leaf);
3891 btrfs_release_path(path);
3892 out:
3893 btrfs_free_path(path);
3894 return ret;
3895 }
3896
3897 /*
3898 * helper to create inode for data relocation.
3899 * the inode is in data relocation tree and its link count is 0
3900 */
3901 static noinline_for_stack
3902 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3903 struct btrfs_block_group_cache *group)
3904 {
3905 struct inode *inode = NULL;
3906 struct btrfs_trans_handle *trans;
3907 struct btrfs_root *root;
3908 struct btrfs_key key;
3909 unsigned long nr;
3910 u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3911 int err = 0;
3912
3913 root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3914 if (IS_ERR(root))
3915 return ERR_CAST(root);
3916
3917 trans = btrfs_start_transaction(root, 6);
3918 if (IS_ERR(trans))
3919 return ERR_CAST(trans);
3920
3921 err = btrfs_find_free_objectid(root, &objectid);
3922 if (err)
3923 goto out;
3924
3925 err = __insert_orphan_inode(trans, root, objectid);
3926 BUG_ON(err);
3927
3928 key.objectid = objectid;
3929 key.type = BTRFS_INODE_ITEM_KEY;
3930 key.offset = 0;
3931 inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
3932 BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3933 BTRFS_I(inode)->index_cnt = group->key.objectid;
3934
3935 err = btrfs_orphan_add(trans, inode);
3936 out:
3937 nr = trans->blocks_used;
3938 btrfs_end_transaction(trans, root);
3939 btrfs_btree_balance_dirty(root, nr);
3940 if (err) {
3941 if (inode)
3942 iput(inode);
3943 inode = ERR_PTR(err);
3944 }
3945 return inode;
3946 }
3947
3948 static struct reloc_control *alloc_reloc_control(void)
3949 {
3950 struct reloc_control *rc;
3951
3952 rc = kzalloc(sizeof(*rc), GFP_NOFS);
3953 if (!rc)
3954 return NULL;
3955
3956 INIT_LIST_HEAD(&rc->reloc_roots);
3957 backref_cache_init(&rc->backref_cache);
3958 mapping_tree_init(&rc->reloc_root_tree);
3959 extent_io_tree_init(&rc->processed_blocks, NULL);
3960 return rc;
3961 }
3962
3963 /*
3964 * function to relocate all extents in a block group.
3965 */
3966 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
3967 {
3968 struct btrfs_fs_info *fs_info = extent_root->fs_info;
3969 struct reloc_control *rc;
3970 struct inode *inode;
3971 struct btrfs_path *path;
3972 int ret;
3973 int rw = 0;
3974 int err = 0;
3975
3976 rc = alloc_reloc_control();
3977 if (!rc)
3978 return -ENOMEM;
3979
3980 rc->extent_root = extent_root;
3981
3982 rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
3983 BUG_ON(!rc->block_group);
3984
3985 if (!rc->block_group->ro) {
3986 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
3987 if (ret) {
3988 err = ret;
3989 goto out;
3990 }
3991 rw = 1;
3992 }
3993
3994 path = btrfs_alloc_path();
3995 if (!path) {
3996 err = -ENOMEM;
3997 goto out;
3998 }
3999
4000 inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4001 path);
4002 btrfs_free_path(path);
4003
4004 if (!IS_ERR(inode))
4005 ret = delete_block_group_cache(fs_info, inode, 0);
4006 else
4007 ret = PTR_ERR(inode);
4008
4009 if (ret && ret != -ENOENT) {
4010 err = ret;
4011 goto out;
4012 }
4013
4014 rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4015 if (IS_ERR(rc->data_inode)) {
4016 err = PTR_ERR(rc->data_inode);
4017 rc->data_inode = NULL;
4018 goto out;
4019 }
4020
4021 printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
4022 (unsigned long long)rc->block_group->key.objectid,
4023 (unsigned long long)rc->block_group->flags);
4024
4025 btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
4026 btrfs_wait_ordered_extents(fs_info->tree_root, 0, 0);
4027
4028 while (1) {
4029 mutex_lock(&fs_info->cleaner_mutex);
4030
4031 btrfs_clean_old_snapshots(fs_info->tree_root);
4032 ret = relocate_block_group(rc);
4033
4034 mutex_unlock(&fs_info->cleaner_mutex);
4035 if (ret < 0) {
4036 err = ret;
4037 goto out;
4038 }
4039
4040 if (rc->extents_found == 0)
4041 break;
4042
4043 printk(KERN_INFO "btrfs: found %llu extents\n",
4044 (unsigned long long)rc->extents_found);
4045
4046 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4047 btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
4048 invalidate_mapping_pages(rc->data_inode->i_mapping,
4049 0, -1);
4050 rc->stage = UPDATE_DATA_PTRS;
4051 }
4052 }
4053
4054 filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4055 rc->block_group->key.objectid,
4056 rc->block_group->key.objectid +
4057 rc->block_group->key.offset - 1);
4058
4059 WARN_ON(rc->block_group->pinned > 0);
4060 WARN_ON(rc->block_group->reserved > 0);
4061 WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4062 out:
4063 if (err && rw)
4064 btrfs_set_block_group_rw(extent_root, rc->block_group);
4065 iput(rc->data_inode);
4066 btrfs_put_block_group(rc->block_group);
4067 kfree(rc);
4068 return err;
4069 }
4070
4071 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4072 {
4073 struct btrfs_trans_handle *trans;
4074 int ret;
4075
4076 trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4077 BUG_ON(IS_ERR(trans));
4078
4079 memset(&root->root_item.drop_progress, 0,
4080 sizeof(root->root_item.drop_progress));
4081 root->root_item.drop_level = 0;
4082 btrfs_set_root_refs(&root->root_item, 0);
4083 ret = btrfs_update_root(trans, root->fs_info->tree_root,
4084 &root->root_key, &root->root_item);
4085 BUG_ON(ret);
4086
4087 ret = btrfs_end_transaction(trans, root->fs_info->tree_root);
4088 BUG_ON(ret);
4089 return 0;
4090 }
4091
4092 /*
4093 * recover relocation interrupted by system crash.
4094 *
4095 * this function resumes merging reloc trees with corresponding fs trees.
4096 * this is important for keeping the sharing of tree blocks
4097 */
4098 int btrfs_recover_relocation(struct btrfs_root *root)
4099 {
4100 LIST_HEAD(reloc_roots);
4101 struct btrfs_key key;
4102 struct btrfs_root *fs_root;
4103 struct btrfs_root *reloc_root;
4104 struct btrfs_path *path;
4105 struct extent_buffer *leaf;
4106 struct reloc_control *rc = NULL;
4107 struct btrfs_trans_handle *trans;
4108 int ret;
4109 int err = 0;
4110
4111 path = btrfs_alloc_path();
4112 if (!path)
4113 return -ENOMEM;
4114 path->reada = -1;
4115
4116 key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4117 key.type = BTRFS_ROOT_ITEM_KEY;
4118 key.offset = (u64)-1;
4119
4120 while (1) {
4121 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4122 path, 0, 0);
4123 if (ret < 0) {
4124 err = ret;
4125 goto out;
4126 }
4127 if (ret > 0) {
4128 if (path->slots[0] == 0)
4129 break;
4130 path->slots[0]--;
4131 }
4132 leaf = path->nodes[0];
4133 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4134 btrfs_release_path(path);
4135
4136 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4137 key.type != BTRFS_ROOT_ITEM_KEY)
4138 break;
4139
4140 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
4141 if (IS_ERR(reloc_root)) {
4142 err = PTR_ERR(reloc_root);
4143 goto out;
4144 }
4145
4146 list_add(&reloc_root->root_list, &reloc_roots);
4147
4148 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4149 fs_root = read_fs_root(root->fs_info,
4150 reloc_root->root_key.offset);
4151 if (IS_ERR(fs_root)) {
4152 ret = PTR_ERR(fs_root);
4153 if (ret != -ENOENT) {
4154 err = ret;
4155 goto out;
4156 }
4157 mark_garbage_root(reloc_root);
4158 }
4159 }
4160
4161 if (key.offset == 0)
4162 break;
4163
4164 key.offset--;
4165 }
4166 btrfs_release_path(path);
4167
4168 if (list_empty(&reloc_roots))
4169 goto out;
4170
4171 rc = alloc_reloc_control();
4172 if (!rc) {
4173 err = -ENOMEM;
4174 goto out;
4175 }
4176
4177 rc->extent_root = root->fs_info->extent_root;
4178
4179 set_reloc_control(rc);
4180
4181 trans = btrfs_join_transaction(rc->extent_root);
4182 if (IS_ERR(trans)) {
4183 unset_reloc_control(rc);
4184 err = PTR_ERR(trans);
4185 goto out_free;
4186 }
4187
4188 rc->merge_reloc_tree = 1;
4189
4190 while (!list_empty(&reloc_roots)) {
4191 reloc_root = list_entry(reloc_roots.next,
4192 struct btrfs_root, root_list);
4193 list_del(&reloc_root->root_list);
4194
4195 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4196 list_add_tail(&reloc_root->root_list,
4197 &rc->reloc_roots);
4198 continue;
4199 }
4200
4201 fs_root = read_fs_root(root->fs_info,
4202 reloc_root->root_key.offset);
4203 BUG_ON(IS_ERR(fs_root));
4204
4205 __add_reloc_root(reloc_root);
4206 fs_root->reloc_root = reloc_root;
4207 }
4208
4209 btrfs_commit_transaction(trans, rc->extent_root);
4210
4211 merge_reloc_roots(rc);
4212
4213 unset_reloc_control(rc);
4214
4215 trans = btrfs_join_transaction(rc->extent_root);
4216 if (IS_ERR(trans))
4217 err = PTR_ERR(trans);
4218 else
4219 btrfs_commit_transaction(trans, rc->extent_root);
4220 out_free:
4221 kfree(rc);
4222 out:
4223 while (!list_empty(&reloc_roots)) {
4224 reloc_root = list_entry(reloc_roots.next,
4225 struct btrfs_root, root_list);
4226 list_del(&reloc_root->root_list);
4227 free_extent_buffer(reloc_root->node);
4228 free_extent_buffer(reloc_root->commit_root);
4229 kfree(reloc_root);
4230 }
4231 btrfs_free_path(path);
4232
4233 if (err == 0) {
4234 /* cleanup orphan inode in data relocation tree */
4235 fs_root = read_fs_root(root->fs_info,
4236 BTRFS_DATA_RELOC_TREE_OBJECTID);
4237 if (IS_ERR(fs_root))
4238 err = PTR_ERR(fs_root);
4239 else
4240 err = btrfs_orphan_cleanup(fs_root);
4241 }
4242 return err;
4243 }
4244
4245 /*
4246 * helper to add ordered checksum for data relocation.
4247 *
4248 * cloning checksum properly handles the nodatasum extents.
4249 * it also saves CPU time to re-calculate the checksum.
4250 */
4251 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4252 {
4253 struct btrfs_ordered_sum *sums;
4254 struct btrfs_sector_sum *sector_sum;
4255 struct btrfs_ordered_extent *ordered;
4256 struct btrfs_root *root = BTRFS_I(inode)->root;
4257 size_t offset;
4258 int ret;
4259 u64 disk_bytenr;
4260 LIST_HEAD(list);
4261
4262 ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4263 BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4264
4265 disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4266 ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4267 disk_bytenr + len - 1, &list, 0);
4268
4269 while (!list_empty(&list)) {
4270 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4271 list_del_init(&sums->list);
4272
4273 sector_sum = sums->sums;
4274 sums->bytenr = ordered->start;
4275
4276 offset = 0;
4277 while (offset < sums->len) {
4278 sector_sum->bytenr += ordered->start - disk_bytenr;
4279 sector_sum++;
4280 offset += root->sectorsize;
4281 }
4282
4283 btrfs_add_ordered_sum(inode, ordered, sums);
4284 }
4285 btrfs_put_ordered_extent(ordered);
4286 return ret;
4287 }
4288
4289 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4290 struct btrfs_root *root, struct extent_buffer *buf,
4291 struct extent_buffer *cow)
4292 {
4293 struct reloc_control *rc;
4294 struct backref_node *node;
4295 int first_cow = 0;
4296 int level;
4297 int ret;
4298
4299 rc = root->fs_info->reloc_ctl;
4300 if (!rc)
4301 return;
4302
4303 BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4304 root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4305
4306 level = btrfs_header_level(buf);
4307 if (btrfs_header_generation(buf) <=
4308 btrfs_root_last_snapshot(&root->root_item))
4309 first_cow = 1;
4310
4311 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4312 rc->create_reloc_tree) {
4313 WARN_ON(!first_cow && level == 0);
4314
4315 node = rc->backref_cache.path[level];
4316 BUG_ON(node->bytenr != buf->start &&
4317 node->new_bytenr != buf->start);
4318
4319 drop_node_buffer(node);
4320 extent_buffer_get(cow);
4321 node->eb = cow;
4322 node->new_bytenr = cow->start;
4323
4324 if (!node->pending) {
4325 list_move_tail(&node->list,
4326 &rc->backref_cache.pending[level]);
4327 node->pending = 1;
4328 }
4329
4330 if (first_cow)
4331 __mark_block_processed(rc, node);
4332
4333 if (first_cow && level > 0)
4334 rc->nodes_relocated += buf->len;
4335 }
4336
4337 if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4338 ret = replace_file_extents(trans, rc, root, cow);
4339 BUG_ON(ret);
4340 }
4341 }
4342
4343 /*
4344 * called before creating snapshot. it calculates metadata reservation
4345 * requried for relocating tree blocks in the snapshot
4346 */
4347 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4348 struct btrfs_pending_snapshot *pending,
4349 u64 *bytes_to_reserve)
4350 {
4351 struct btrfs_root *root;
4352 struct reloc_control *rc;
4353
4354 root = pending->root;
4355 if (!root->reloc_root)
4356 return;
4357
4358 rc = root->fs_info->reloc_ctl;
4359 if (!rc->merge_reloc_tree)
4360 return;
4361
4362 root = root->reloc_root;
4363 BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4364 /*
4365 * relocation is in the stage of merging trees. the space
4366 * used by merging a reloc tree is twice the size of
4367 * relocated tree nodes in the worst case. half for cowing
4368 * the reloc tree, half for cowing the fs tree. the space
4369 * used by cowing the reloc tree will be freed after the
4370 * tree is dropped. if we create snapshot, cowing the fs
4371 * tree may use more space than it frees. so we need
4372 * reserve extra space.
4373 */
4374 *bytes_to_reserve += rc->nodes_relocated;
4375 }
4376
4377 /*
4378 * called after snapshot is created. migrate block reservation
4379 * and create reloc root for the newly created snapshot
4380 */
4381 void btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4382 struct btrfs_pending_snapshot *pending)
4383 {
4384 struct btrfs_root *root = pending->root;
4385 struct btrfs_root *reloc_root;
4386 struct btrfs_root *new_root;
4387 struct reloc_control *rc;
4388 int ret;
4389
4390 if (!root->reloc_root)
4391 return;
4392
4393 rc = root->fs_info->reloc_ctl;
4394 rc->merging_rsv_size += rc->nodes_relocated;
4395
4396 if (rc->merge_reloc_tree) {
4397 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4398 rc->block_rsv,
4399 rc->nodes_relocated);
4400 BUG_ON(ret);
4401 }
4402
4403 new_root = pending->snap;
4404 reloc_root = create_reloc_root(trans, root->reloc_root,
4405 new_root->root_key.objectid);
4406
4407 __add_reloc_root(reloc_root);
4408 new_root->reloc_root = reloc_root;
4409
4410 if (rc->create_reloc_tree) {
4411 ret = clone_backref_node(trans, rc, root, reloc_root);
4412 BUG_ON(ret);
4413 }
4414 }