1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2009 Oracle. All rights reserved.
6 #include <linux/sched.h>
7 #include <linux/pagemap.h>
8 #include <linux/writeback.h>
9 #include <linux/blkdev.h>
10 #include <linux/rbtree.h>
11 #include <linux/slab.h>
14 #include "transaction.h"
17 #include "btrfs_inode.h"
18 #include "async-thread.h"
19 #include "free-space-cache.h"
20 #include "inode-map.h"
22 #include "print-tree.h"
23 #include "delalloc-space.h"
24 #include "block-group.h"
27 * backref_node, mapping_node and tree_block start with this
30 struct rb_node rb_node;
35 * present a tree block in the backref cache
38 struct rb_node rb_node;
42 /* objectid of tree block owner, can be not uptodate */
44 /* link to pending, changed or detached list */
45 struct list_head list;
46 /* list of upper level blocks reference this block */
47 struct list_head upper;
48 /* list of child blocks in the cache */
49 struct list_head lower;
50 /* NULL if this node is not tree root */
51 struct btrfs_root *root;
52 /* extent buffer got by COW the block */
53 struct extent_buffer *eb;
54 /* level of tree block */
56 /* is the block in non-reference counted tree */
57 unsigned int cowonly:1;
58 /* 1 if no child node in the cache */
59 unsigned int lowest:1;
60 /* is the extent buffer locked */
61 unsigned int locked:1;
62 /* has the block been processed */
63 unsigned int processed:1;
64 /* have backrefs of this block been checked */
65 unsigned int checked:1;
67 * 1 if corresponding block has been cowed but some upper
68 * level block pointers may not point to the new location
70 unsigned int pending:1;
72 * 1 if the backref node isn't connected to any other
75 unsigned int detached:1;
79 * present a block pointer in the backref cache
82 struct list_head list[2];
83 struct backref_node *node[2];
88 #define RELOCATION_RESERVED_NODES 256
90 struct backref_cache {
91 /* red black tree of all backref nodes in the cache */
92 struct rb_root rb_root;
93 /* for passing backref nodes to btrfs_reloc_cow_block */
94 struct backref_node *path[BTRFS_MAX_LEVEL];
96 * list of blocks that have been cowed but some block
97 * pointers in upper level blocks may not reflect the
100 struct list_head pending[BTRFS_MAX_LEVEL];
101 /* list of backref nodes with no child node */
102 struct list_head leaves;
103 /* list of blocks that have been cowed in current transaction */
104 struct list_head changed;
105 /* list of detached backref node. */
106 struct list_head detached;
115 * map address of tree root to tree
117 struct mapping_node {
118 struct rb_node rb_node;
123 struct mapping_tree {
124 struct rb_root rb_root;
129 * present a tree block to process
132 struct rb_node rb_node;
134 struct btrfs_key key;
135 unsigned int level:8;
136 unsigned int key_ready:1;
139 #define MAX_EXTENTS 128
141 struct file_extent_cluster {
144 u64 boundary[MAX_EXTENTS];
148 struct reloc_control {
149 /* block group to relocate */
150 struct btrfs_block_group *block_group;
152 struct btrfs_root *extent_root;
153 /* inode for moving data */
154 struct inode *data_inode;
156 struct btrfs_block_rsv *block_rsv;
158 struct backref_cache backref_cache;
160 struct file_extent_cluster cluster;
161 /* tree blocks have been processed */
162 struct extent_io_tree processed_blocks;
163 /* map start of tree root to corresponding reloc tree */
164 struct mapping_tree reloc_root_tree;
165 /* list of reloc trees */
166 struct list_head reloc_roots;
167 /* list of subvolume trees that get relocated */
168 struct list_head dirty_subvol_roots;
169 /* size of metadata reservation for merging reloc trees */
170 u64 merging_rsv_size;
171 /* size of relocated tree nodes */
173 /* reserved size for block group relocation*/
179 unsigned int stage:8;
180 unsigned int create_reloc_tree:1;
181 unsigned int merge_reloc_tree:1;
182 unsigned int found_file_extent:1;
185 /* stages of data relocation */
186 #define MOVE_DATA_EXTENTS 0
187 #define UPDATE_DATA_PTRS 1
189 static void remove_backref_node(struct backref_cache *cache,
190 struct backref_node *node);
191 static void __mark_block_processed(struct reloc_control *rc,
192 struct backref_node *node);
194 static void mapping_tree_init(struct mapping_tree *tree)
196 tree->rb_root = RB_ROOT;
197 spin_lock_init(&tree->lock);
200 static void backref_cache_init(struct backref_cache *cache)
203 cache->rb_root = RB_ROOT;
204 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
205 INIT_LIST_HEAD(&cache->pending[i]);
206 INIT_LIST_HEAD(&cache->changed);
207 INIT_LIST_HEAD(&cache->detached);
208 INIT_LIST_HEAD(&cache->leaves);
211 static void backref_cache_cleanup(struct backref_cache *cache)
213 struct backref_node *node;
216 while (!list_empty(&cache->detached)) {
217 node = list_entry(cache->detached.next,
218 struct backref_node, list);
219 remove_backref_node(cache, node);
222 while (!list_empty(&cache->leaves)) {
223 node = list_entry(cache->leaves.next,
224 struct backref_node, lower);
225 remove_backref_node(cache, node);
228 cache->last_trans = 0;
230 for (i = 0; i < BTRFS_MAX_LEVEL; i++)
231 ASSERT(list_empty(&cache->pending[i]));
232 ASSERT(list_empty(&cache->changed));
233 ASSERT(list_empty(&cache->detached));
234 ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
235 ASSERT(!cache->nr_nodes);
236 ASSERT(!cache->nr_edges);
239 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
241 struct backref_node *node;
243 node = kzalloc(sizeof(*node), GFP_NOFS);
245 INIT_LIST_HEAD(&node->list);
246 INIT_LIST_HEAD(&node->upper);
247 INIT_LIST_HEAD(&node->lower);
248 RB_CLEAR_NODE(&node->rb_node);
254 static void free_backref_node(struct backref_cache *cache,
255 struct backref_node *node)
263 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
265 struct backref_edge *edge;
267 edge = kzalloc(sizeof(*edge), GFP_NOFS);
273 static void free_backref_edge(struct backref_cache *cache,
274 struct backref_edge *edge)
282 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
283 struct rb_node *node)
285 struct rb_node **p = &root->rb_node;
286 struct rb_node *parent = NULL;
287 struct tree_entry *entry;
291 entry = rb_entry(parent, struct tree_entry, rb_node);
293 if (bytenr < entry->bytenr)
295 else if (bytenr > entry->bytenr)
301 rb_link_node(node, parent, p);
302 rb_insert_color(node, root);
306 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
308 struct rb_node *n = root->rb_node;
309 struct tree_entry *entry;
312 entry = rb_entry(n, struct tree_entry, rb_node);
314 if (bytenr < entry->bytenr)
316 else if (bytenr > entry->bytenr)
324 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
327 struct btrfs_fs_info *fs_info = NULL;
328 struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
331 fs_info = bnode->root->fs_info;
332 btrfs_panic(fs_info, errno,
333 "Inconsistency in backref cache found at offset %llu",
338 * walk up backref nodes until reach node presents tree root
340 static struct backref_node *walk_up_backref(struct backref_node *node,
341 struct backref_edge *edges[],
344 struct backref_edge *edge;
347 while (!list_empty(&node->upper)) {
348 edge = list_entry(node->upper.next,
349 struct backref_edge, list[LOWER]);
351 node = edge->node[UPPER];
353 BUG_ON(node->detached);
359 * walk down backref nodes to find start of next reference path
361 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
364 struct backref_edge *edge;
365 struct backref_node *lower;
369 edge = edges[idx - 1];
370 lower = edge->node[LOWER];
371 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
375 edge = list_entry(edge->list[LOWER].next,
376 struct backref_edge, list[LOWER]);
377 edges[idx - 1] = edge;
379 return edge->node[UPPER];
385 static void unlock_node_buffer(struct backref_node *node)
388 btrfs_tree_unlock(node->eb);
393 static void drop_node_buffer(struct backref_node *node)
396 unlock_node_buffer(node);
397 free_extent_buffer(node->eb);
402 static void drop_backref_node(struct backref_cache *tree,
403 struct backref_node *node)
405 BUG_ON(!list_empty(&node->upper));
407 drop_node_buffer(node);
408 list_del(&node->list);
409 list_del(&node->lower);
410 if (!RB_EMPTY_NODE(&node->rb_node))
411 rb_erase(&node->rb_node, &tree->rb_root);
412 free_backref_node(tree, node);
416 * remove a backref node from the backref cache
418 static void remove_backref_node(struct backref_cache *cache,
419 struct backref_node *node)
421 struct backref_node *upper;
422 struct backref_edge *edge;
427 BUG_ON(!node->lowest && !node->detached);
428 while (!list_empty(&node->upper)) {
429 edge = list_entry(node->upper.next, struct backref_edge,
431 upper = edge->node[UPPER];
432 list_del(&edge->list[LOWER]);
433 list_del(&edge->list[UPPER]);
434 free_backref_edge(cache, edge);
436 if (RB_EMPTY_NODE(&upper->rb_node)) {
437 BUG_ON(!list_empty(&node->upper));
438 drop_backref_node(cache, node);
444 * add the node to leaf node list if no other
445 * child block cached.
447 if (list_empty(&upper->lower)) {
448 list_add_tail(&upper->lower, &cache->leaves);
453 drop_backref_node(cache, node);
456 static void update_backref_node(struct backref_cache *cache,
457 struct backref_node *node, u64 bytenr)
459 struct rb_node *rb_node;
460 rb_erase(&node->rb_node, &cache->rb_root);
461 node->bytenr = bytenr;
462 rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
464 backref_tree_panic(rb_node, -EEXIST, bytenr);
468 * update backref cache after a transaction commit
470 static int update_backref_cache(struct btrfs_trans_handle *trans,
471 struct backref_cache *cache)
473 struct backref_node *node;
476 if (cache->last_trans == 0) {
477 cache->last_trans = trans->transid;
481 if (cache->last_trans == trans->transid)
485 * detached nodes are used to avoid unnecessary backref
486 * lookup. transaction commit changes the extent tree.
487 * so the detached nodes are no longer useful.
489 while (!list_empty(&cache->detached)) {
490 node = list_entry(cache->detached.next,
491 struct backref_node, list);
492 remove_backref_node(cache, node);
495 while (!list_empty(&cache->changed)) {
496 node = list_entry(cache->changed.next,
497 struct backref_node, list);
498 list_del_init(&node->list);
499 BUG_ON(node->pending);
500 update_backref_node(cache, node, node->new_bytenr);
504 * some nodes can be left in the pending list if there were
505 * errors during processing the pending nodes.
507 for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
508 list_for_each_entry(node, &cache->pending[level], list) {
509 BUG_ON(!node->pending);
510 if (node->bytenr == node->new_bytenr)
512 update_backref_node(cache, node, node->new_bytenr);
516 cache->last_trans = 0;
521 static int should_ignore_root(struct btrfs_root *root)
523 struct btrfs_root *reloc_root;
525 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
528 reloc_root = root->reloc_root;
532 if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
533 root->fs_info->running_transaction->transid - 1)
536 * if there is reloc tree and it was created in previous
537 * transaction backref lookup can find the reloc tree,
538 * so backref node for the fs tree root is useless for
544 * find reloc tree by address of tree root
546 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
549 struct rb_node *rb_node;
550 struct mapping_node *node;
551 struct btrfs_root *root = NULL;
553 spin_lock(&rc->reloc_root_tree.lock);
554 rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
556 node = rb_entry(rb_node, struct mapping_node, rb_node);
557 root = (struct btrfs_root *)node->data;
559 spin_unlock(&rc->reloc_root_tree.lock);
563 static int is_cowonly_root(u64 root_objectid)
565 if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
566 root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
567 root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
568 root_objectid == BTRFS_DEV_TREE_OBJECTID ||
569 root_objectid == BTRFS_TREE_LOG_OBJECTID ||
570 root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
571 root_objectid == BTRFS_UUID_TREE_OBJECTID ||
572 root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
573 root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
578 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
581 struct btrfs_key key;
583 key.objectid = root_objectid;
584 key.type = BTRFS_ROOT_ITEM_KEY;
585 if (is_cowonly_root(root_objectid))
588 key.offset = (u64)-1;
590 return btrfs_get_fs_root(fs_info, &key, false);
593 static noinline_for_stack
594 int find_inline_backref(struct extent_buffer *leaf, int slot,
595 unsigned long *ptr, unsigned long *end)
597 struct btrfs_key key;
598 struct btrfs_extent_item *ei;
599 struct btrfs_tree_block_info *bi;
602 btrfs_item_key_to_cpu(leaf, &key, slot);
604 item_size = btrfs_item_size_nr(leaf, slot);
605 if (item_size < sizeof(*ei)) {
606 btrfs_print_v0_err(leaf->fs_info);
607 btrfs_handle_fs_error(leaf->fs_info, -EINVAL, NULL);
610 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
611 WARN_ON(!(btrfs_extent_flags(leaf, ei) &
612 BTRFS_EXTENT_FLAG_TREE_BLOCK));
614 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
615 item_size <= sizeof(*ei) + sizeof(*bi)) {
616 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
619 if (key.type == BTRFS_METADATA_ITEM_KEY &&
620 item_size <= sizeof(*ei)) {
621 WARN_ON(item_size < sizeof(*ei));
625 if (key.type == BTRFS_EXTENT_ITEM_KEY) {
626 bi = (struct btrfs_tree_block_info *)(ei + 1);
627 *ptr = (unsigned long)(bi + 1);
629 *ptr = (unsigned long)(ei + 1);
631 *end = (unsigned long)ei + item_size;
636 * build backref tree for a given tree block. root of the backref tree
637 * corresponds the tree block, leaves of the backref tree correspond
638 * roots of b-trees that reference the tree block.
640 * the basic idea of this function is check backrefs of a given block
641 * to find upper level blocks that reference the block, and then check
642 * backrefs of these upper level blocks recursively. the recursion stop
643 * when tree root is reached or backrefs for the block is cached.
645 * NOTE: if we find backrefs for a block are cached, we know backrefs
646 * for all upper level blocks that directly/indirectly reference the
647 * block are also cached.
649 static noinline_for_stack
650 struct backref_node *build_backref_tree(struct reloc_control *rc,
651 struct btrfs_key *node_key,
652 int level, u64 bytenr)
654 struct backref_cache *cache = &rc->backref_cache;
655 struct btrfs_path *path1; /* For searching extent root */
656 struct btrfs_path *path2; /* For searching parent of TREE_BLOCK_REF */
657 struct extent_buffer *eb;
658 struct btrfs_root *root;
659 struct backref_node *cur;
660 struct backref_node *upper;
661 struct backref_node *lower;
662 struct backref_node *node = NULL;
663 struct backref_node *exist = NULL;
664 struct backref_edge *edge;
665 struct rb_node *rb_node;
666 struct btrfs_key key;
669 LIST_HEAD(list); /* Pending edge list, upper node needs to be checked */
674 bool need_check = true;
676 path1 = btrfs_alloc_path();
677 path2 = btrfs_alloc_path();
678 if (!path1 || !path2) {
682 path1->reada = READA_FORWARD;
683 path2->reada = READA_FORWARD;
685 node = alloc_backref_node(cache);
691 node->bytenr = bytenr;
698 key.objectid = cur->bytenr;
699 key.type = BTRFS_METADATA_ITEM_KEY;
700 key.offset = (u64)-1;
702 path1->search_commit_root = 1;
703 path1->skip_locking = 1;
704 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
711 ASSERT(path1->slots[0]);
715 WARN_ON(cur->checked);
716 if (!list_empty(&cur->upper)) {
718 * the backref was added previously when processing
719 * backref of type BTRFS_TREE_BLOCK_REF_KEY
721 ASSERT(list_is_singular(&cur->upper));
722 edge = list_entry(cur->upper.next, struct backref_edge,
724 ASSERT(list_empty(&edge->list[UPPER]));
725 exist = edge->node[UPPER];
727 * add the upper level block to pending list if we need
731 list_add_tail(&edge->list[UPPER], &list);
738 eb = path1->nodes[0];
741 if (path1->slots[0] >= btrfs_header_nritems(eb)) {
742 ret = btrfs_next_leaf(rc->extent_root, path1);
749 eb = path1->nodes[0];
752 btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
753 if (key.objectid != cur->bytenr) {
758 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
759 key.type == BTRFS_METADATA_ITEM_KEY) {
760 ret = find_inline_backref(eb, path1->slots[0],
768 /* update key for inline back ref */
769 struct btrfs_extent_inline_ref *iref;
771 iref = (struct btrfs_extent_inline_ref *)ptr;
772 type = btrfs_get_extent_inline_ref_type(eb, iref,
773 BTRFS_REF_TYPE_BLOCK);
774 if (type == BTRFS_REF_TYPE_INVALID) {
779 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
781 WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
782 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
786 * Parent node found and matches current inline ref, no need to
787 * rebuild this node for this inline ref.
790 ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
791 exist->owner == key.offset) ||
792 (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
793 exist->bytenr == key.offset))) {
798 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */
799 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
800 if (key.objectid == key.offset) {
802 * Only root blocks of reloc trees use backref
803 * pointing to itself.
805 root = find_reloc_root(rc, cur->bytenr);
811 edge = alloc_backref_edge(cache);
816 rb_node = tree_search(&cache->rb_root, key.offset);
818 upper = alloc_backref_node(cache);
820 free_backref_edge(cache, edge);
824 upper->bytenr = key.offset;
825 upper->level = cur->level + 1;
827 * backrefs for the upper level block isn't
828 * cached, add the block to pending list
830 list_add_tail(&edge->list[UPPER], &list);
832 upper = rb_entry(rb_node, struct backref_node,
834 ASSERT(upper->checked);
835 INIT_LIST_HEAD(&edge->list[UPPER]);
837 list_add_tail(&edge->list[LOWER], &cur->upper);
838 edge->node[LOWER] = cur;
839 edge->node[UPPER] = upper;
842 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
844 btrfs_print_v0_err(rc->extent_root->fs_info);
845 btrfs_handle_fs_error(rc->extent_root->fs_info, err,
848 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
853 * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset
854 * means the root objectid. We need to search the tree to get
857 root = read_fs_root(rc->extent_root->fs_info, key.offset);
863 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
866 if (btrfs_root_level(&root->root_item) == cur->level) {
868 ASSERT(btrfs_root_bytenr(&root->root_item) ==
870 if (should_ignore_root(root))
871 list_add(&cur->list, &useless);
877 level = cur->level + 1;
879 /* Search the tree to find parent blocks referring the block. */
880 path2->search_commit_root = 1;
881 path2->skip_locking = 1;
882 path2->lowest_level = level;
883 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
884 path2->lowest_level = 0;
889 if (ret > 0 && path2->slots[level] > 0)
890 path2->slots[level]--;
892 eb = path2->nodes[level];
893 if (btrfs_node_blockptr(eb, path2->slots[level]) !=
895 btrfs_err(root->fs_info,
896 "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
897 cur->bytenr, level - 1,
898 root->root_key.objectid,
899 node_key->objectid, node_key->type,
907 /* Add all nodes and edges in the path */
908 for (; level < BTRFS_MAX_LEVEL; level++) {
909 if (!path2->nodes[level]) {
910 ASSERT(btrfs_root_bytenr(&root->root_item) ==
912 if (should_ignore_root(root))
913 list_add(&lower->list, &useless);
919 edge = alloc_backref_edge(cache);
925 eb = path2->nodes[level];
926 rb_node = tree_search(&cache->rb_root, eb->start);
928 upper = alloc_backref_node(cache);
930 free_backref_edge(cache, edge);
934 upper->bytenr = eb->start;
935 upper->owner = btrfs_header_owner(eb);
936 upper->level = lower->level + 1;
937 if (!test_bit(BTRFS_ROOT_REF_COWS,
942 * if we know the block isn't shared
943 * we can void checking its backrefs.
945 if (btrfs_block_can_be_shared(root, eb))
951 * add the block to pending list if we
952 * need check its backrefs, we only do this once
953 * while walking up a tree as we will catch
954 * anything else later on.
956 if (!upper->checked && need_check) {
958 list_add_tail(&edge->list[UPPER],
963 INIT_LIST_HEAD(&edge->list[UPPER]);
966 upper = rb_entry(rb_node, struct backref_node,
968 ASSERT(upper->checked);
969 INIT_LIST_HEAD(&edge->list[UPPER]);
971 upper->owner = btrfs_header_owner(eb);
973 list_add_tail(&edge->list[LOWER], &lower->upper);
974 edge->node[LOWER] = lower;
975 edge->node[UPPER] = upper;
982 btrfs_release_path(path2);
985 ptr += btrfs_extent_inline_ref_size(key.type);
995 btrfs_release_path(path1);
1000 /* the pending list isn't empty, take the first block to process */
1001 if (!list_empty(&list)) {
1002 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1003 list_del_init(&edge->list[UPPER]);
1004 cur = edge->node[UPPER];
1009 * everything goes well, connect backref nodes and insert backref nodes
1012 ASSERT(node->checked);
1013 cowonly = node->cowonly;
1015 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1018 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1019 list_add_tail(&node->lower, &cache->leaves);
1022 list_for_each_entry(edge, &node->upper, list[LOWER])
1023 list_add_tail(&edge->list[UPPER], &list);
1025 while (!list_empty(&list)) {
1026 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1027 list_del_init(&edge->list[UPPER]);
1028 upper = edge->node[UPPER];
1029 if (upper->detached) {
1030 list_del(&edge->list[LOWER]);
1031 lower = edge->node[LOWER];
1032 free_backref_edge(cache, edge);
1033 if (list_empty(&lower->upper))
1034 list_add(&lower->list, &useless);
1038 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1039 if (upper->lowest) {
1040 list_del_init(&upper->lower);
1044 list_add_tail(&edge->list[UPPER], &upper->lower);
1048 if (!upper->checked) {
1050 * Still want to blow up for developers since this is a
1057 if (cowonly != upper->cowonly) {
1064 rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1067 backref_tree_panic(rb_node, -EEXIST,
1071 list_add_tail(&edge->list[UPPER], &upper->lower);
1073 list_for_each_entry(edge, &upper->upper, list[LOWER])
1074 list_add_tail(&edge->list[UPPER], &list);
1077 * process useless backref nodes. backref nodes for tree leaves
1078 * are deleted from the cache. backref nodes for upper level
1079 * tree blocks are left in the cache to avoid unnecessary backref
1082 while (!list_empty(&useless)) {
1083 upper = list_entry(useless.next, struct backref_node, list);
1084 list_del_init(&upper->list);
1085 ASSERT(list_empty(&upper->upper));
1088 if (upper->lowest) {
1089 list_del_init(&upper->lower);
1092 while (!list_empty(&upper->lower)) {
1093 edge = list_entry(upper->lower.next,
1094 struct backref_edge, list[UPPER]);
1095 list_del(&edge->list[UPPER]);
1096 list_del(&edge->list[LOWER]);
1097 lower = edge->node[LOWER];
1098 free_backref_edge(cache, edge);
1100 if (list_empty(&lower->upper))
1101 list_add(&lower->list, &useless);
1103 __mark_block_processed(rc, upper);
1104 if (upper->level > 0) {
1105 list_add(&upper->list, &cache->detached);
1106 upper->detached = 1;
1108 rb_erase(&upper->rb_node, &cache->rb_root);
1109 free_backref_node(cache, upper);
1113 btrfs_free_path(path1);
1114 btrfs_free_path(path2);
1116 while (!list_empty(&useless)) {
1117 lower = list_entry(useless.next,
1118 struct backref_node, list);
1119 list_del_init(&lower->list);
1121 while (!list_empty(&list)) {
1122 edge = list_first_entry(&list, struct backref_edge,
1124 list_del(&edge->list[UPPER]);
1125 list_del(&edge->list[LOWER]);
1126 lower = edge->node[LOWER];
1127 upper = edge->node[UPPER];
1128 free_backref_edge(cache, edge);
1131 * Lower is no longer linked to any upper backref nodes
1132 * and isn't in the cache, we can free it ourselves.
1134 if (list_empty(&lower->upper) &&
1135 RB_EMPTY_NODE(&lower->rb_node))
1136 list_add(&lower->list, &useless);
1138 if (!RB_EMPTY_NODE(&upper->rb_node))
1141 /* Add this guy's upper edges to the list to process */
1142 list_for_each_entry(edge, &upper->upper, list[LOWER])
1143 list_add_tail(&edge->list[UPPER], &list);
1144 if (list_empty(&upper->upper))
1145 list_add(&upper->list, &useless);
1148 while (!list_empty(&useless)) {
1149 lower = list_entry(useless.next,
1150 struct backref_node, list);
1151 list_del_init(&lower->list);
1154 free_backref_node(cache, lower);
1157 free_backref_node(cache, node);
1158 return ERR_PTR(err);
1160 ASSERT(!node || !node->detached);
1165 * helper to add backref node for the newly created snapshot.
1166 * the backref node is created by cloning backref node that
1167 * corresponds to root of source tree
1169 static int clone_backref_node(struct btrfs_trans_handle *trans,
1170 struct reloc_control *rc,
1171 struct btrfs_root *src,
1172 struct btrfs_root *dest)
1174 struct btrfs_root *reloc_root = src->reloc_root;
1175 struct backref_cache *cache = &rc->backref_cache;
1176 struct backref_node *node = NULL;
1177 struct backref_node *new_node;
1178 struct backref_edge *edge;
1179 struct backref_edge *new_edge;
1180 struct rb_node *rb_node;
1182 if (cache->last_trans > 0)
1183 update_backref_cache(trans, cache);
1185 rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1187 node = rb_entry(rb_node, struct backref_node, rb_node);
1191 BUG_ON(node->new_bytenr != reloc_root->node->start);
1195 rb_node = tree_search(&cache->rb_root,
1196 reloc_root->commit_root->start);
1198 node = rb_entry(rb_node, struct backref_node,
1200 BUG_ON(node->detached);
1207 new_node = alloc_backref_node(cache);
1211 new_node->bytenr = dest->node->start;
1212 new_node->level = node->level;
1213 new_node->lowest = node->lowest;
1214 new_node->checked = 1;
1215 new_node->root = dest;
1217 if (!node->lowest) {
1218 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1219 new_edge = alloc_backref_edge(cache);
1223 new_edge->node[UPPER] = new_node;
1224 new_edge->node[LOWER] = edge->node[LOWER];
1225 list_add_tail(&new_edge->list[UPPER],
1229 list_add_tail(&new_node->lower, &cache->leaves);
1232 rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1233 &new_node->rb_node);
1235 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1237 if (!new_node->lowest) {
1238 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1239 list_add_tail(&new_edge->list[LOWER],
1240 &new_edge->node[LOWER]->upper);
1245 while (!list_empty(&new_node->lower)) {
1246 new_edge = list_entry(new_node->lower.next,
1247 struct backref_edge, list[UPPER]);
1248 list_del(&new_edge->list[UPPER]);
1249 free_backref_edge(cache, new_edge);
1251 free_backref_node(cache, new_node);
1256 * helper to add 'address of tree root -> reloc tree' mapping
1258 static int __must_check __add_reloc_root(struct btrfs_root *root)
1260 struct btrfs_fs_info *fs_info = root->fs_info;
1261 struct rb_node *rb_node;
1262 struct mapping_node *node;
1263 struct reloc_control *rc = fs_info->reloc_ctl;
1265 node = kmalloc(sizeof(*node), GFP_NOFS);
1269 node->bytenr = root->node->start;
1272 spin_lock(&rc->reloc_root_tree.lock);
1273 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1274 node->bytenr, &node->rb_node);
1275 spin_unlock(&rc->reloc_root_tree.lock);
1277 btrfs_panic(fs_info, -EEXIST,
1278 "Duplicate root found for start=%llu while inserting into relocation tree",
1282 list_add_tail(&root->root_list, &rc->reloc_roots);
1287 * helper to delete the 'address of tree root -> reloc tree'
1290 static void __del_reloc_root(struct btrfs_root *root)
1292 struct btrfs_fs_info *fs_info = root->fs_info;
1293 struct rb_node *rb_node;
1294 struct mapping_node *node = NULL;
1295 struct reloc_control *rc = fs_info->reloc_ctl;
1297 if (rc && root->node) {
1298 spin_lock(&rc->reloc_root_tree.lock);
1299 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1302 node = rb_entry(rb_node, struct mapping_node, rb_node);
1303 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1305 spin_unlock(&rc->reloc_root_tree.lock);
1308 BUG_ON((struct btrfs_root *)node->data != root);
1311 spin_lock(&fs_info->trans_lock);
1312 list_del_init(&root->root_list);
1313 spin_unlock(&fs_info->trans_lock);
1318 * helper to update the 'address of tree root -> reloc tree'
1321 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1323 struct btrfs_fs_info *fs_info = root->fs_info;
1324 struct rb_node *rb_node;
1325 struct mapping_node *node = NULL;
1326 struct reloc_control *rc = fs_info->reloc_ctl;
1328 spin_lock(&rc->reloc_root_tree.lock);
1329 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1332 node = rb_entry(rb_node, struct mapping_node, rb_node);
1333 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1335 spin_unlock(&rc->reloc_root_tree.lock);
1339 BUG_ON((struct btrfs_root *)node->data != root);
1341 spin_lock(&rc->reloc_root_tree.lock);
1342 node->bytenr = new_bytenr;
1343 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1344 node->bytenr, &node->rb_node);
1345 spin_unlock(&rc->reloc_root_tree.lock);
1347 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1351 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1352 struct btrfs_root *root, u64 objectid)
1354 struct btrfs_fs_info *fs_info = root->fs_info;
1355 struct btrfs_root *reloc_root;
1356 struct extent_buffer *eb;
1357 struct btrfs_root_item *root_item;
1358 struct btrfs_key root_key;
1361 root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1364 root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1365 root_key.type = BTRFS_ROOT_ITEM_KEY;
1366 root_key.offset = objectid;
1368 if (root->root_key.objectid == objectid) {
1369 u64 commit_root_gen;
1371 /* called by btrfs_init_reloc_root */
1372 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1373 BTRFS_TREE_RELOC_OBJECTID);
1376 * Set the last_snapshot field to the generation of the commit
1377 * root - like this ctree.c:btrfs_block_can_be_shared() behaves
1378 * correctly (returns true) when the relocation root is created
1379 * either inside the critical section of a transaction commit
1380 * (through transaction.c:qgroup_account_snapshot()) and when
1381 * it's created before the transaction commit is started.
1383 commit_root_gen = btrfs_header_generation(root->commit_root);
1384 btrfs_set_root_last_snapshot(&root->root_item, commit_root_gen);
1387 * called by btrfs_reloc_post_snapshot_hook.
1388 * the source tree is a reloc tree, all tree blocks
1389 * modified after it was created have RELOC flag
1390 * set in their headers. so it's OK to not update
1391 * the 'last_snapshot'.
1393 ret = btrfs_copy_root(trans, root, root->node, &eb,
1394 BTRFS_TREE_RELOC_OBJECTID);
1398 memcpy(root_item, &root->root_item, sizeof(*root_item));
1399 btrfs_set_root_bytenr(root_item, eb->start);
1400 btrfs_set_root_level(root_item, btrfs_header_level(eb));
1401 btrfs_set_root_generation(root_item, trans->transid);
1403 if (root->root_key.objectid == objectid) {
1404 btrfs_set_root_refs(root_item, 0);
1405 memset(&root_item->drop_progress, 0,
1406 sizeof(struct btrfs_disk_key));
1407 root_item->drop_level = 0;
1410 btrfs_tree_unlock(eb);
1411 free_extent_buffer(eb);
1413 ret = btrfs_insert_root(trans, fs_info->tree_root,
1414 &root_key, root_item);
1418 reloc_root = btrfs_read_fs_root(fs_info->tree_root, &root_key);
1419 BUG_ON(IS_ERR(reloc_root));
1420 reloc_root->last_trans = trans->transid;
1425 * create reloc tree for a given fs tree. reloc tree is just a
1426 * snapshot of the fs tree with special root objectid.
1428 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1429 struct btrfs_root *root)
1431 struct btrfs_fs_info *fs_info = root->fs_info;
1432 struct btrfs_root *reloc_root;
1433 struct reloc_control *rc = fs_info->reloc_ctl;
1434 struct btrfs_block_rsv *rsv;
1439 * The subvolume has reloc tree but the swap is finished, no need to
1440 * create/update the dead reloc tree
1442 if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state))
1445 if (root->reloc_root) {
1446 reloc_root = root->reloc_root;
1447 reloc_root->last_trans = trans->transid;
1451 if (!rc || !rc->create_reloc_tree ||
1452 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1455 if (!trans->reloc_reserved) {
1456 rsv = trans->block_rsv;
1457 trans->block_rsv = rc->block_rsv;
1460 reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1462 trans->block_rsv = rsv;
1464 ret = __add_reloc_root(reloc_root);
1466 root->reloc_root = reloc_root;
1471 * update root item of reloc tree
1473 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1474 struct btrfs_root *root)
1476 struct btrfs_fs_info *fs_info = root->fs_info;
1477 struct btrfs_root *reloc_root;
1478 struct btrfs_root_item *root_item;
1481 if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state) ||
1485 reloc_root = root->reloc_root;
1486 root_item = &reloc_root->root_item;
1488 /* root->reloc_root will stay until current relocation finished */
1489 if (fs_info->reloc_ctl->merge_reloc_tree &&
1490 btrfs_root_refs(root_item) == 0) {
1491 set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
1492 __del_reloc_root(reloc_root);
1495 if (reloc_root->commit_root != reloc_root->node) {
1496 btrfs_set_root_node(root_item, reloc_root->node);
1497 free_extent_buffer(reloc_root->commit_root);
1498 reloc_root->commit_root = btrfs_root_node(reloc_root);
1501 ret = btrfs_update_root(trans, fs_info->tree_root,
1502 &reloc_root->root_key, root_item);
1510 * helper to find first cached inode with inode number >= objectid
1513 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1515 struct rb_node *node;
1516 struct rb_node *prev;
1517 struct btrfs_inode *entry;
1518 struct inode *inode;
1520 spin_lock(&root->inode_lock);
1522 node = root->inode_tree.rb_node;
1526 entry = rb_entry(node, struct btrfs_inode, rb_node);
1528 if (objectid < btrfs_ino(entry))
1529 node = node->rb_left;
1530 else if (objectid > btrfs_ino(entry))
1531 node = node->rb_right;
1537 entry = rb_entry(prev, struct btrfs_inode, rb_node);
1538 if (objectid <= btrfs_ino(entry)) {
1542 prev = rb_next(prev);
1546 entry = rb_entry(node, struct btrfs_inode, rb_node);
1547 inode = igrab(&entry->vfs_inode);
1549 spin_unlock(&root->inode_lock);
1553 objectid = btrfs_ino(entry) + 1;
1554 if (cond_resched_lock(&root->inode_lock))
1557 node = rb_next(node);
1559 spin_unlock(&root->inode_lock);
1563 static int in_block_group(u64 bytenr, struct btrfs_block_group *block_group)
1565 if (bytenr >= block_group->start &&
1566 bytenr < block_group->start + block_group->length)
1572 * get new location of data
1574 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1575 u64 bytenr, u64 num_bytes)
1577 struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1578 struct btrfs_path *path;
1579 struct btrfs_file_extent_item *fi;
1580 struct extent_buffer *leaf;
1583 path = btrfs_alloc_path();
1587 bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1588 ret = btrfs_lookup_file_extent(NULL, root, path,
1589 btrfs_ino(BTRFS_I(reloc_inode)), bytenr, 0);
1597 leaf = path->nodes[0];
1598 fi = btrfs_item_ptr(leaf, path->slots[0],
1599 struct btrfs_file_extent_item);
1601 BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1602 btrfs_file_extent_compression(leaf, fi) ||
1603 btrfs_file_extent_encryption(leaf, fi) ||
1604 btrfs_file_extent_other_encoding(leaf, fi));
1606 if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1611 *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1614 btrfs_free_path(path);
1619 * update file extent items in the tree leaf to point to
1620 * the new locations.
1622 static noinline_for_stack
1623 int replace_file_extents(struct btrfs_trans_handle *trans,
1624 struct reloc_control *rc,
1625 struct btrfs_root *root,
1626 struct extent_buffer *leaf)
1628 struct btrfs_fs_info *fs_info = root->fs_info;
1629 struct btrfs_key key;
1630 struct btrfs_file_extent_item *fi;
1631 struct inode *inode = NULL;
1643 if (rc->stage != UPDATE_DATA_PTRS)
1646 /* reloc trees always use full backref */
1647 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1648 parent = leaf->start;
1652 nritems = btrfs_header_nritems(leaf);
1653 for (i = 0; i < nritems; i++) {
1654 struct btrfs_ref ref = { 0 };
1657 btrfs_item_key_to_cpu(leaf, &key, i);
1658 if (key.type != BTRFS_EXTENT_DATA_KEY)
1660 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1661 if (btrfs_file_extent_type(leaf, fi) ==
1662 BTRFS_FILE_EXTENT_INLINE)
1664 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1665 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1668 if (!in_block_group(bytenr, rc->block_group))
1672 * if we are modifying block in fs tree, wait for readpage
1673 * to complete and drop the extent cache
1675 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1677 inode = find_next_inode(root, key.objectid);
1679 } else if (inode && btrfs_ino(BTRFS_I(inode)) < key.objectid) {
1680 btrfs_add_delayed_iput(inode);
1681 inode = find_next_inode(root, key.objectid);
1683 if (inode && btrfs_ino(BTRFS_I(inode)) == key.objectid) {
1685 btrfs_file_extent_num_bytes(leaf, fi);
1686 WARN_ON(!IS_ALIGNED(key.offset,
1687 fs_info->sectorsize));
1688 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
1690 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1695 btrfs_drop_extent_cache(BTRFS_I(inode),
1696 key.offset, end, 1);
1697 unlock_extent(&BTRFS_I(inode)->io_tree,
1702 ret = get_new_location(rc->data_inode, &new_bytenr,
1706 * Don't have to abort since we've not changed anything
1707 * in the file extent yet.
1712 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1715 key.offset -= btrfs_file_extent_offset(leaf, fi);
1716 btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, new_bytenr,
1718 ref.real_root = root->root_key.objectid;
1719 btrfs_init_data_ref(&ref, btrfs_header_owner(leaf),
1720 key.objectid, key.offset);
1721 ret = btrfs_inc_extent_ref(trans, &ref);
1723 btrfs_abort_transaction(trans, ret);
1727 btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, bytenr,
1729 ref.real_root = root->root_key.objectid;
1730 btrfs_init_data_ref(&ref, btrfs_header_owner(leaf),
1731 key.objectid, key.offset);
1732 ret = btrfs_free_extent(trans, &ref);
1734 btrfs_abort_transaction(trans, ret);
1739 btrfs_mark_buffer_dirty(leaf);
1741 btrfs_add_delayed_iput(inode);
1745 static noinline_for_stack
1746 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1747 struct btrfs_path *path, int level)
1749 struct btrfs_disk_key key1;
1750 struct btrfs_disk_key key2;
1751 btrfs_node_key(eb, &key1, slot);
1752 btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1753 return memcmp(&key1, &key2, sizeof(key1));
1757 * try to replace tree blocks in fs tree with the new blocks
1758 * in reloc tree. tree blocks haven't been modified since the
1759 * reloc tree was create can be replaced.
1761 * if a block was replaced, level of the block + 1 is returned.
1762 * if no block got replaced, 0 is returned. if there are other
1763 * errors, a negative error number is returned.
1765 static noinline_for_stack
1766 int replace_path(struct btrfs_trans_handle *trans, struct reloc_control *rc,
1767 struct btrfs_root *dest, struct btrfs_root *src,
1768 struct btrfs_path *path, struct btrfs_key *next_key,
1769 int lowest_level, int max_level)
1771 struct btrfs_fs_info *fs_info = dest->fs_info;
1772 struct extent_buffer *eb;
1773 struct extent_buffer *parent;
1774 struct btrfs_ref ref = { 0 };
1775 struct btrfs_key key;
1787 BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1788 BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1790 last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1792 slot = path->slots[lowest_level];
1793 btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1795 eb = btrfs_lock_root_node(dest);
1796 btrfs_set_lock_blocking_write(eb);
1797 level = btrfs_header_level(eb);
1799 if (level < lowest_level) {
1800 btrfs_tree_unlock(eb);
1801 free_extent_buffer(eb);
1806 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1809 btrfs_set_lock_blocking_write(eb);
1812 next_key->objectid = (u64)-1;
1813 next_key->type = (u8)-1;
1814 next_key->offset = (u64)-1;
1819 struct btrfs_key first_key;
1821 level = btrfs_header_level(parent);
1822 BUG_ON(level < lowest_level);
1824 ret = btrfs_bin_search(parent, &key, level, &slot);
1827 if (ret && slot > 0)
1830 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1831 btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1833 old_bytenr = btrfs_node_blockptr(parent, slot);
1834 blocksize = fs_info->nodesize;
1835 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1836 btrfs_node_key_to_cpu(parent, &first_key, slot);
1838 if (level <= max_level) {
1839 eb = path->nodes[level];
1840 new_bytenr = btrfs_node_blockptr(eb,
1841 path->slots[level]);
1842 new_ptr_gen = btrfs_node_ptr_generation(eb,
1843 path->slots[level]);
1849 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1854 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1855 memcmp_node_keys(parent, slot, path, level)) {
1856 if (level <= lowest_level) {
1861 eb = read_tree_block(fs_info, old_bytenr, old_ptr_gen,
1862 level - 1, &first_key);
1866 } else if (!extent_buffer_uptodate(eb)) {
1868 free_extent_buffer(eb);
1871 btrfs_tree_lock(eb);
1873 ret = btrfs_cow_block(trans, dest, eb, parent,
1877 btrfs_set_lock_blocking_write(eb);
1879 btrfs_tree_unlock(parent);
1880 free_extent_buffer(parent);
1887 btrfs_tree_unlock(parent);
1888 free_extent_buffer(parent);
1893 btrfs_node_key_to_cpu(path->nodes[level], &key,
1894 path->slots[level]);
1895 btrfs_release_path(path);
1897 path->lowest_level = level;
1898 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1899 path->lowest_level = 0;
1903 * Info qgroup to trace both subtrees.
1905 * We must trace both trees.
1906 * 1) Tree reloc subtree
1907 * If not traced, we will leak data numbers
1909 * If not traced, we will double count old data
1911 * We don't scan the subtree right now, but only record
1912 * the swapped tree blocks.
1913 * The real subtree rescan is delayed until we have new
1914 * CoW on the subtree root node before transaction commit.
1916 ret = btrfs_qgroup_add_swapped_blocks(trans, dest,
1917 rc->block_group, parent, slot,
1918 path->nodes[level], path->slots[level],
1923 * swap blocks in fs tree and reloc tree.
1925 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1926 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1927 btrfs_mark_buffer_dirty(parent);
1929 btrfs_set_node_blockptr(path->nodes[level],
1930 path->slots[level], old_bytenr);
1931 btrfs_set_node_ptr_generation(path->nodes[level],
1932 path->slots[level], old_ptr_gen);
1933 btrfs_mark_buffer_dirty(path->nodes[level]);
1935 btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, old_bytenr,
1936 blocksize, path->nodes[level]->start);
1937 ref.skip_qgroup = true;
1938 btrfs_init_tree_ref(&ref, level - 1, src->root_key.objectid);
1939 ret = btrfs_inc_extent_ref(trans, &ref);
1941 btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, new_bytenr,
1943 ref.skip_qgroup = true;
1944 btrfs_init_tree_ref(&ref, level - 1, dest->root_key.objectid);
1945 ret = btrfs_inc_extent_ref(trans, &ref);
1948 btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, new_bytenr,
1949 blocksize, path->nodes[level]->start);
1950 btrfs_init_tree_ref(&ref, level - 1, src->root_key.objectid);
1951 ref.skip_qgroup = true;
1952 ret = btrfs_free_extent(trans, &ref);
1955 btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, old_bytenr,
1957 btrfs_init_tree_ref(&ref, level - 1, dest->root_key.objectid);
1958 ref.skip_qgroup = true;
1959 ret = btrfs_free_extent(trans, &ref);
1962 btrfs_unlock_up_safe(path, 0);
1967 btrfs_tree_unlock(parent);
1968 free_extent_buffer(parent);
1973 * helper to find next relocated block in reloc tree
1975 static noinline_for_stack
1976 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1979 struct extent_buffer *eb;
1984 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1986 for (i = 0; i < *level; i++) {
1987 free_extent_buffer(path->nodes[i]);
1988 path->nodes[i] = NULL;
1991 for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1992 eb = path->nodes[i];
1993 nritems = btrfs_header_nritems(eb);
1994 while (path->slots[i] + 1 < nritems) {
1996 if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
2003 free_extent_buffer(path->nodes[i]);
2004 path->nodes[i] = NULL;
2010 * walk down reloc tree to find relocated block of lowest level
2012 static noinline_for_stack
2013 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
2016 struct btrfs_fs_info *fs_info = root->fs_info;
2017 struct extent_buffer *eb = NULL;
2024 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
2026 for (i = *level; i > 0; i--) {
2027 struct btrfs_key first_key;
2029 eb = path->nodes[i];
2030 nritems = btrfs_header_nritems(eb);
2031 while (path->slots[i] < nritems) {
2032 ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
2033 if (ptr_gen > last_snapshot)
2037 if (path->slots[i] >= nritems) {
2048 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2049 btrfs_node_key_to_cpu(eb, &first_key, path->slots[i]);
2050 eb = read_tree_block(fs_info, bytenr, ptr_gen, i - 1,
2054 } else if (!extent_buffer_uptodate(eb)) {
2055 free_extent_buffer(eb);
2058 BUG_ON(btrfs_header_level(eb) != i - 1);
2059 path->nodes[i - 1] = eb;
2060 path->slots[i - 1] = 0;
2066 * invalidate extent cache for file extents whose key in range of
2067 * [min_key, max_key)
2069 static int invalidate_extent_cache(struct btrfs_root *root,
2070 struct btrfs_key *min_key,
2071 struct btrfs_key *max_key)
2073 struct btrfs_fs_info *fs_info = root->fs_info;
2074 struct inode *inode = NULL;
2079 objectid = min_key->objectid;
2084 if (objectid > max_key->objectid)
2087 inode = find_next_inode(root, objectid);
2090 ino = btrfs_ino(BTRFS_I(inode));
2092 if (ino > max_key->objectid) {
2098 if (!S_ISREG(inode->i_mode))
2101 if (unlikely(min_key->objectid == ino)) {
2102 if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2104 if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2107 start = min_key->offset;
2108 WARN_ON(!IS_ALIGNED(start, fs_info->sectorsize));
2114 if (unlikely(max_key->objectid == ino)) {
2115 if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2117 if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2120 if (max_key->offset == 0)
2122 end = max_key->offset;
2123 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
2130 /* the lock_extent waits for readpage to complete */
2131 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2132 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 1);
2133 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2138 static int find_next_key(struct btrfs_path *path, int level,
2139 struct btrfs_key *key)
2142 while (level < BTRFS_MAX_LEVEL) {
2143 if (!path->nodes[level])
2145 if (path->slots[level] + 1 <
2146 btrfs_header_nritems(path->nodes[level])) {
2147 btrfs_node_key_to_cpu(path->nodes[level], key,
2148 path->slots[level] + 1);
2157 * Insert current subvolume into reloc_control::dirty_subvol_roots
2159 static void insert_dirty_subvol(struct btrfs_trans_handle *trans,
2160 struct reloc_control *rc,
2161 struct btrfs_root *root)
2163 struct btrfs_root *reloc_root = root->reloc_root;
2164 struct btrfs_root_item *reloc_root_item;
2166 /* @root must be a subvolume tree root with a valid reloc tree */
2167 ASSERT(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
2170 reloc_root_item = &reloc_root->root_item;
2171 memset(&reloc_root_item->drop_progress, 0,
2172 sizeof(reloc_root_item->drop_progress));
2173 reloc_root_item->drop_level = 0;
2174 btrfs_set_root_refs(reloc_root_item, 0);
2175 btrfs_update_reloc_root(trans, root);
2177 if (list_empty(&root->reloc_dirty_list)) {
2178 btrfs_grab_fs_root(root);
2179 list_add_tail(&root->reloc_dirty_list, &rc->dirty_subvol_roots);
2183 static int clean_dirty_subvols(struct reloc_control *rc)
2185 struct btrfs_root *root;
2186 struct btrfs_root *next;
2190 list_for_each_entry_safe(root, next, &rc->dirty_subvol_roots,
2192 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
2193 /* Merged subvolume, cleanup its reloc root */
2194 struct btrfs_root *reloc_root = root->reloc_root;
2196 list_del_init(&root->reloc_dirty_list);
2197 root->reloc_root = NULL;
2200 ret2 = btrfs_drop_snapshot(reloc_root, NULL, 0, 1);
2201 if (ret2 < 0 && !ret)
2204 clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
2205 btrfs_put_fs_root(root);
2207 /* Orphan reloc tree, just clean it up */
2208 ret2 = btrfs_drop_snapshot(root, NULL, 0, 1);
2209 if (ret2 < 0 && !ret)
2217 * merge the relocated tree blocks in reloc tree with corresponding
2220 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2221 struct btrfs_root *root)
2223 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2224 struct btrfs_key key;
2225 struct btrfs_key next_key;
2226 struct btrfs_trans_handle *trans = NULL;
2227 struct btrfs_root *reloc_root;
2228 struct btrfs_root_item *root_item;
2229 struct btrfs_path *path;
2230 struct extent_buffer *leaf;
2238 path = btrfs_alloc_path();
2241 path->reada = READA_FORWARD;
2243 reloc_root = root->reloc_root;
2244 root_item = &reloc_root->root_item;
2246 if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2247 level = btrfs_root_level(root_item);
2248 atomic_inc(&reloc_root->node->refs);
2249 path->nodes[level] = reloc_root->node;
2250 path->slots[level] = 0;
2252 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2254 level = root_item->drop_level;
2256 path->lowest_level = level;
2257 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2258 path->lowest_level = 0;
2260 btrfs_free_path(path);
2264 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2265 path->slots[level]);
2266 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2268 btrfs_unlock_up_safe(path, 0);
2271 min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2272 memset(&next_key, 0, sizeof(next_key));
2275 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2276 BTRFS_RESERVE_FLUSH_ALL);
2281 trans = btrfs_start_transaction(root, 0);
2282 if (IS_ERR(trans)) {
2283 err = PTR_ERR(trans);
2287 trans->block_rsv = rc->block_rsv;
2292 ret = walk_down_reloc_tree(reloc_root, path, &level);
2300 if (!find_next_key(path, level, &key) &&
2301 btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2304 ret = replace_path(trans, rc, root, reloc_root, path,
2305 &next_key, level, max_level);
2314 btrfs_node_key_to_cpu(path->nodes[level], &key,
2315 path->slots[level]);
2319 ret = walk_up_reloc_tree(reloc_root, path, &level);
2325 * save the merging progress in the drop_progress.
2326 * this is OK since root refs == 1 in this case.
2328 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2329 path->slots[level]);
2330 root_item->drop_level = level;
2332 btrfs_end_transaction_throttle(trans);
2335 btrfs_btree_balance_dirty(fs_info);
2337 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2338 invalidate_extent_cache(root, &key, &next_key);
2342 * handle the case only one block in the fs tree need to be
2343 * relocated and the block is tree root.
2345 leaf = btrfs_lock_root_node(root);
2346 ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2347 btrfs_tree_unlock(leaf);
2348 free_extent_buffer(leaf);
2352 btrfs_free_path(path);
2355 insert_dirty_subvol(trans, rc, root);
2358 btrfs_end_transaction_throttle(trans);
2360 btrfs_btree_balance_dirty(fs_info);
2362 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2363 invalidate_extent_cache(root, &key, &next_key);
2368 static noinline_for_stack
2369 int prepare_to_merge(struct reloc_control *rc, int err)
2371 struct btrfs_root *root = rc->extent_root;
2372 struct btrfs_fs_info *fs_info = root->fs_info;
2373 struct btrfs_root *reloc_root;
2374 struct btrfs_trans_handle *trans;
2375 LIST_HEAD(reloc_roots);
2379 mutex_lock(&fs_info->reloc_mutex);
2380 rc->merging_rsv_size += fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2381 rc->merging_rsv_size += rc->nodes_relocated * 2;
2382 mutex_unlock(&fs_info->reloc_mutex);
2386 num_bytes = rc->merging_rsv_size;
2387 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2388 BTRFS_RESERVE_FLUSH_ALL);
2393 trans = btrfs_join_transaction(rc->extent_root);
2394 if (IS_ERR(trans)) {
2396 btrfs_block_rsv_release(fs_info, rc->block_rsv,
2398 return PTR_ERR(trans);
2402 if (num_bytes != rc->merging_rsv_size) {
2403 btrfs_end_transaction(trans);
2404 btrfs_block_rsv_release(fs_info, rc->block_rsv,
2410 rc->merge_reloc_tree = 1;
2412 while (!list_empty(&rc->reloc_roots)) {
2413 reloc_root = list_entry(rc->reloc_roots.next,
2414 struct btrfs_root, root_list);
2415 list_del_init(&reloc_root->root_list);
2417 root = read_fs_root(fs_info, reloc_root->root_key.offset);
2418 BUG_ON(IS_ERR(root));
2419 BUG_ON(root->reloc_root != reloc_root);
2422 * set reference count to 1, so btrfs_recover_relocation
2423 * knows it should resumes merging
2426 btrfs_set_root_refs(&reloc_root->root_item, 1);
2427 btrfs_update_reloc_root(trans, root);
2429 list_add(&reloc_root->root_list, &reloc_roots);
2432 list_splice(&reloc_roots, &rc->reloc_roots);
2435 btrfs_commit_transaction(trans);
2437 btrfs_end_transaction(trans);
2441 static noinline_for_stack
2442 void free_reloc_roots(struct list_head *list)
2444 struct btrfs_root *reloc_root;
2446 while (!list_empty(list)) {
2447 reloc_root = list_entry(list->next, struct btrfs_root,
2449 __del_reloc_root(reloc_root);
2450 free_extent_buffer(reloc_root->node);
2451 free_extent_buffer(reloc_root->commit_root);
2452 reloc_root->node = NULL;
2453 reloc_root->commit_root = NULL;
2457 static noinline_for_stack
2458 void merge_reloc_roots(struct reloc_control *rc)
2460 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2461 struct btrfs_root *root;
2462 struct btrfs_root *reloc_root;
2463 LIST_HEAD(reloc_roots);
2467 root = rc->extent_root;
2470 * this serializes us with btrfs_record_root_in_transaction,
2471 * we have to make sure nobody is in the middle of
2472 * adding their roots to the list while we are
2475 mutex_lock(&fs_info->reloc_mutex);
2476 list_splice_init(&rc->reloc_roots, &reloc_roots);
2477 mutex_unlock(&fs_info->reloc_mutex);
2479 while (!list_empty(&reloc_roots)) {
2481 reloc_root = list_entry(reloc_roots.next,
2482 struct btrfs_root, root_list);
2484 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2485 root = read_fs_root(fs_info,
2486 reloc_root->root_key.offset);
2487 BUG_ON(IS_ERR(root));
2488 BUG_ON(root->reloc_root != reloc_root);
2490 ret = merge_reloc_root(rc, root);
2492 if (list_empty(&reloc_root->root_list))
2493 list_add_tail(&reloc_root->root_list,
2498 list_del_init(&reloc_root->root_list);
2499 /* Don't forget to queue this reloc root for cleanup */
2500 list_add_tail(&reloc_root->reloc_dirty_list,
2501 &rc->dirty_subvol_roots);
2511 btrfs_handle_fs_error(fs_info, ret, NULL);
2512 if (!list_empty(&reloc_roots))
2513 free_reloc_roots(&reloc_roots);
2515 /* new reloc root may be added */
2516 mutex_lock(&fs_info->reloc_mutex);
2517 list_splice_init(&rc->reloc_roots, &reloc_roots);
2518 mutex_unlock(&fs_info->reloc_mutex);
2519 if (!list_empty(&reloc_roots))
2520 free_reloc_roots(&reloc_roots);
2523 BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2526 static void free_block_list(struct rb_root *blocks)
2528 struct tree_block *block;
2529 struct rb_node *rb_node;
2530 while ((rb_node = rb_first(blocks))) {
2531 block = rb_entry(rb_node, struct tree_block, rb_node);
2532 rb_erase(rb_node, blocks);
2537 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2538 struct btrfs_root *reloc_root)
2540 struct btrfs_fs_info *fs_info = reloc_root->fs_info;
2541 struct btrfs_root *root;
2543 if (reloc_root->last_trans == trans->transid)
2546 root = read_fs_root(fs_info, reloc_root->root_key.offset);
2547 BUG_ON(IS_ERR(root));
2548 BUG_ON(root->reloc_root != reloc_root);
2550 return btrfs_record_root_in_trans(trans, root);
2553 static noinline_for_stack
2554 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2555 struct reloc_control *rc,
2556 struct backref_node *node,
2557 struct backref_edge *edges[])
2559 struct backref_node *next;
2560 struct btrfs_root *root;
2566 next = walk_up_backref(next, edges, &index);
2569 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2571 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2572 record_reloc_root_in_trans(trans, root);
2576 btrfs_record_root_in_trans(trans, root);
2577 root = root->reloc_root;
2579 if (next->new_bytenr != root->node->start) {
2580 BUG_ON(next->new_bytenr);
2581 BUG_ON(!list_empty(&next->list));
2582 next->new_bytenr = root->node->start;
2584 list_add_tail(&next->list,
2585 &rc->backref_cache.changed);
2586 __mark_block_processed(rc, next);
2592 next = walk_down_backref(edges, &index);
2593 if (!next || next->level <= node->level)
2600 /* setup backref node path for btrfs_reloc_cow_block */
2602 rc->backref_cache.path[next->level] = next;
2605 next = edges[index]->node[UPPER];
2611 * select a tree root for relocation. return NULL if the block
2612 * is reference counted. we should use do_relocation() in this
2613 * case. return a tree root pointer if the block isn't reference
2614 * counted. return -ENOENT if the block is root of reloc tree.
2616 static noinline_for_stack
2617 struct btrfs_root *select_one_root(struct backref_node *node)
2619 struct backref_node *next;
2620 struct btrfs_root *root;
2621 struct btrfs_root *fs_root = NULL;
2622 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2628 next = walk_up_backref(next, edges, &index);
2632 /* no other choice for non-references counted tree */
2633 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2636 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2642 next = walk_down_backref(edges, &index);
2643 if (!next || next->level <= node->level)
2648 return ERR_PTR(-ENOENT);
2652 static noinline_for_stack
2653 u64 calcu_metadata_size(struct reloc_control *rc,
2654 struct backref_node *node, int reserve)
2656 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2657 struct backref_node *next = node;
2658 struct backref_edge *edge;
2659 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2663 BUG_ON(reserve && node->processed);
2668 if (next->processed && (reserve || next != node))
2671 num_bytes += fs_info->nodesize;
2673 if (list_empty(&next->upper))
2676 edge = list_entry(next->upper.next,
2677 struct backref_edge, list[LOWER]);
2678 edges[index++] = edge;
2679 next = edge->node[UPPER];
2681 next = walk_down_backref(edges, &index);
2686 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2687 struct reloc_control *rc,
2688 struct backref_node *node)
2690 struct btrfs_root *root = rc->extent_root;
2691 struct btrfs_fs_info *fs_info = root->fs_info;
2696 num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2698 trans->block_rsv = rc->block_rsv;
2699 rc->reserved_bytes += num_bytes;
2702 * We are under a transaction here so we can only do limited flushing.
2703 * If we get an enospc just kick back -EAGAIN so we know to drop the
2704 * transaction and try to refill when we can flush all the things.
2706 ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2707 BTRFS_RESERVE_FLUSH_LIMIT);
2709 tmp = fs_info->nodesize * RELOCATION_RESERVED_NODES;
2710 while (tmp <= rc->reserved_bytes)
2713 * only one thread can access block_rsv at this point,
2714 * so we don't need hold lock to protect block_rsv.
2715 * we expand more reservation size here to allow enough
2716 * space for relocation and we will return earlier in
2719 rc->block_rsv->size = tmp + fs_info->nodesize *
2720 RELOCATION_RESERVED_NODES;
2728 * relocate a block tree, and then update pointers in upper level
2729 * blocks that reference the block to point to the new location.
2731 * if called by link_to_upper, the block has already been relocated.
2732 * in that case this function just updates pointers.
2734 static int do_relocation(struct btrfs_trans_handle *trans,
2735 struct reloc_control *rc,
2736 struct backref_node *node,
2737 struct btrfs_key *key,
2738 struct btrfs_path *path, int lowest)
2740 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2741 struct backref_node *upper;
2742 struct backref_edge *edge;
2743 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2744 struct btrfs_root *root;
2745 struct extent_buffer *eb;
2753 BUG_ON(lowest && node->eb);
2755 path->lowest_level = node->level + 1;
2756 rc->backref_cache.path[node->level] = node;
2757 list_for_each_entry(edge, &node->upper, list[LOWER]) {
2758 struct btrfs_key first_key;
2759 struct btrfs_ref ref = { 0 };
2763 upper = edge->node[UPPER];
2764 root = select_reloc_root(trans, rc, upper, edges);
2767 if (upper->eb && !upper->locked) {
2769 ret = btrfs_bin_search(upper->eb, key,
2770 upper->level, &slot);
2776 bytenr = btrfs_node_blockptr(upper->eb, slot);
2777 if (node->eb->start == bytenr)
2780 drop_node_buffer(upper);
2784 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2791 btrfs_release_path(path);
2796 upper->eb = path->nodes[upper->level];
2797 path->nodes[upper->level] = NULL;
2799 BUG_ON(upper->eb != path->nodes[upper->level]);
2803 path->locks[upper->level] = 0;
2805 slot = path->slots[upper->level];
2806 btrfs_release_path(path);
2808 ret = btrfs_bin_search(upper->eb, key, upper->level,
2817 bytenr = btrfs_node_blockptr(upper->eb, slot);
2819 if (bytenr != node->bytenr) {
2820 btrfs_err(root->fs_info,
2821 "lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu",
2822 bytenr, node->bytenr, slot,
2828 if (node->eb->start == bytenr)
2832 blocksize = root->fs_info->nodesize;
2833 generation = btrfs_node_ptr_generation(upper->eb, slot);
2834 btrfs_node_key_to_cpu(upper->eb, &first_key, slot);
2835 eb = read_tree_block(fs_info, bytenr, generation,
2836 upper->level - 1, &first_key);
2840 } else if (!extent_buffer_uptodate(eb)) {
2841 free_extent_buffer(eb);
2845 btrfs_tree_lock(eb);
2846 btrfs_set_lock_blocking_write(eb);
2849 ret = btrfs_cow_block(trans, root, eb, upper->eb,
2851 btrfs_tree_unlock(eb);
2852 free_extent_buffer(eb);
2857 BUG_ON(node->eb != eb);
2859 btrfs_set_node_blockptr(upper->eb, slot,
2861 btrfs_set_node_ptr_generation(upper->eb, slot,
2863 btrfs_mark_buffer_dirty(upper->eb);
2865 btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF,
2866 node->eb->start, blocksize,
2868 ref.real_root = root->root_key.objectid;
2869 btrfs_init_tree_ref(&ref, node->level,
2870 btrfs_header_owner(upper->eb));
2871 ret = btrfs_inc_extent_ref(trans, &ref);
2874 ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2878 if (!upper->pending)
2879 drop_node_buffer(upper);
2881 unlock_node_buffer(upper);
2886 if (!err && node->pending) {
2887 drop_node_buffer(node);
2888 list_move_tail(&node->list, &rc->backref_cache.changed);
2892 path->lowest_level = 0;
2893 BUG_ON(err == -ENOSPC);
2897 static int link_to_upper(struct btrfs_trans_handle *trans,
2898 struct reloc_control *rc,
2899 struct backref_node *node,
2900 struct btrfs_path *path)
2902 struct btrfs_key key;
2904 btrfs_node_key_to_cpu(node->eb, &key, 0);
2905 return do_relocation(trans, rc, node, &key, path, 0);
2908 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2909 struct reloc_control *rc,
2910 struct btrfs_path *path, int err)
2913 struct backref_cache *cache = &rc->backref_cache;
2914 struct backref_node *node;
2918 for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2919 while (!list_empty(&cache->pending[level])) {
2920 node = list_entry(cache->pending[level].next,
2921 struct backref_node, list);
2922 list_move_tail(&node->list, &list);
2923 BUG_ON(!node->pending);
2926 ret = link_to_upper(trans, rc, node, path);
2931 list_splice_init(&list, &cache->pending[level]);
2936 static void mark_block_processed(struct reloc_control *rc,
2937 u64 bytenr, u32 blocksize)
2939 set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2943 static void __mark_block_processed(struct reloc_control *rc,
2944 struct backref_node *node)
2947 if (node->level == 0 ||
2948 in_block_group(node->bytenr, rc->block_group)) {
2949 blocksize = rc->extent_root->fs_info->nodesize;
2950 mark_block_processed(rc, node->bytenr, blocksize);
2952 node->processed = 1;
2956 * mark a block and all blocks directly/indirectly reference the block
2959 static void update_processed_blocks(struct reloc_control *rc,
2960 struct backref_node *node)
2962 struct backref_node *next = node;
2963 struct backref_edge *edge;
2964 struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2970 if (next->processed)
2973 __mark_block_processed(rc, next);
2975 if (list_empty(&next->upper))
2978 edge = list_entry(next->upper.next,
2979 struct backref_edge, list[LOWER]);
2980 edges[index++] = edge;
2981 next = edge->node[UPPER];
2983 next = walk_down_backref(edges, &index);
2987 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2989 u32 blocksize = rc->extent_root->fs_info->nodesize;
2991 if (test_range_bit(&rc->processed_blocks, bytenr,
2992 bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2997 static int get_tree_block_key(struct btrfs_fs_info *fs_info,
2998 struct tree_block *block)
3000 struct extent_buffer *eb;
3002 BUG_ON(block->key_ready);
3003 eb = read_tree_block(fs_info, block->bytenr, block->key.offset,
3004 block->level, NULL);
3007 } else if (!extent_buffer_uptodate(eb)) {
3008 free_extent_buffer(eb);
3011 if (block->level == 0)
3012 btrfs_item_key_to_cpu(eb, &block->key, 0);
3014 btrfs_node_key_to_cpu(eb, &block->key, 0);
3015 free_extent_buffer(eb);
3016 block->key_ready = 1;
3021 * helper function to relocate a tree block
3023 static int relocate_tree_block(struct btrfs_trans_handle *trans,
3024 struct reloc_control *rc,
3025 struct backref_node *node,
3026 struct btrfs_key *key,
3027 struct btrfs_path *path)
3029 struct btrfs_root *root;
3035 BUG_ON(node->processed);
3036 root = select_one_root(node);
3037 if (root == ERR_PTR(-ENOENT)) {
3038 update_processed_blocks(rc, node);
3042 if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
3043 ret = reserve_metadata_space(trans, rc, node);
3049 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
3050 BUG_ON(node->new_bytenr);
3051 BUG_ON(!list_empty(&node->list));
3052 btrfs_record_root_in_trans(trans, root);
3053 root = root->reloc_root;
3054 node->new_bytenr = root->node->start;
3056 list_add_tail(&node->list, &rc->backref_cache.changed);
3058 path->lowest_level = node->level;
3059 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
3060 btrfs_release_path(path);
3065 update_processed_blocks(rc, node);
3067 ret = do_relocation(trans, rc, node, key, path, 1);
3070 if (ret || node->level == 0 || node->cowonly)
3071 remove_backref_node(&rc->backref_cache, node);
3076 * relocate a list of blocks
3078 static noinline_for_stack
3079 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
3080 struct reloc_control *rc, struct rb_root *blocks)
3082 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3083 struct backref_node *node;
3084 struct btrfs_path *path;
3085 struct tree_block *block;
3086 struct tree_block *next;
3090 path = btrfs_alloc_path();
3093 goto out_free_blocks;
3096 /* Kick in readahead for tree blocks with missing keys */
3097 rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3098 if (!block->key_ready)
3099 readahead_tree_block(fs_info, block->bytenr);
3102 /* Get first keys */
3103 rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3104 if (!block->key_ready) {
3105 err = get_tree_block_key(fs_info, block);
3111 /* Do tree relocation */
3112 rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3113 node = build_backref_tree(rc, &block->key,
3114 block->level, block->bytenr);
3116 err = PTR_ERR(node);
3120 ret = relocate_tree_block(trans, rc, node, &block->key,
3123 if (ret != -EAGAIN || &block->rb_node == rb_first(blocks))
3129 err = finish_pending_nodes(trans, rc, path, err);
3132 btrfs_free_path(path);
3134 free_block_list(blocks);
3138 static noinline_for_stack
3139 int prealloc_file_extent_cluster(struct inode *inode,
3140 struct file_extent_cluster *cluster)
3145 u64 offset = BTRFS_I(inode)->index_cnt;
3149 u64 prealloc_start = cluster->start - offset;
3150 u64 prealloc_end = cluster->end - offset;
3152 struct extent_changeset *data_reserved = NULL;
3154 BUG_ON(cluster->start != cluster->boundary[0]);
3157 ret = btrfs_check_data_free_space(inode, &data_reserved, prealloc_start,
3158 prealloc_end + 1 - prealloc_start);
3162 cur_offset = prealloc_start;
3163 while (nr < cluster->nr) {
3164 start = cluster->boundary[nr] - offset;
3165 if (nr + 1 < cluster->nr)
3166 end = cluster->boundary[nr + 1] - 1 - offset;
3168 end = cluster->end - offset;
3170 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3171 num_bytes = end + 1 - start;
3172 if (cur_offset < start)
3173 btrfs_free_reserved_data_space(inode, data_reserved,
3174 cur_offset, start - cur_offset);
3175 ret = btrfs_prealloc_file_range(inode, 0, start,
3176 num_bytes, num_bytes,
3177 end + 1, &alloc_hint);
3178 cur_offset = end + 1;
3179 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3184 if (cur_offset < prealloc_end)
3185 btrfs_free_reserved_data_space(inode, data_reserved,
3186 cur_offset, prealloc_end + 1 - cur_offset);
3188 inode_unlock(inode);
3189 extent_changeset_free(data_reserved);
3193 static noinline_for_stack
3194 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3197 struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3198 struct extent_map *em;
3201 em = alloc_extent_map();
3206 em->len = end + 1 - start;
3207 em->block_len = em->len;
3208 em->block_start = block_start;
3209 set_bit(EXTENT_FLAG_PINNED, &em->flags);
3211 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3213 write_lock(&em_tree->lock);
3214 ret = add_extent_mapping(em_tree, em, 0);
3215 write_unlock(&em_tree->lock);
3216 if (ret != -EEXIST) {
3217 free_extent_map(em);
3220 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
3222 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3226 static int relocate_file_extent_cluster(struct inode *inode,
3227 struct file_extent_cluster *cluster)
3229 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3232 u64 offset = BTRFS_I(inode)->index_cnt;
3233 unsigned long index;
3234 unsigned long last_index;
3236 struct file_ra_state *ra;
3237 gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3244 ra = kzalloc(sizeof(*ra), GFP_NOFS);
3248 ret = prealloc_file_extent_cluster(inode, cluster);
3252 file_ra_state_init(ra, inode->i_mapping);
3254 ret = setup_extent_mapping(inode, cluster->start - offset,
3255 cluster->end - offset, cluster->start);
3259 index = (cluster->start - offset) >> PAGE_SHIFT;
3260 last_index = (cluster->end - offset) >> PAGE_SHIFT;
3261 while (index <= last_index) {
3262 ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
3267 page = find_lock_page(inode->i_mapping, index);
3269 page_cache_sync_readahead(inode->i_mapping,
3271 last_index + 1 - index);
3272 page = find_or_create_page(inode->i_mapping, index,
3275 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3277 btrfs_delalloc_release_extents(BTRFS_I(inode),
3284 if (PageReadahead(page)) {
3285 page_cache_async_readahead(inode->i_mapping,
3286 ra, NULL, page, index,
3287 last_index + 1 - index);
3290 if (!PageUptodate(page)) {
3291 btrfs_readpage(NULL, page);
3293 if (!PageUptodate(page)) {
3296 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3298 btrfs_delalloc_release_extents(BTRFS_I(inode),
3305 page_start = page_offset(page);
3306 page_end = page_start + PAGE_SIZE - 1;
3308 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3310 set_page_extent_mapped(page);
3312 if (nr < cluster->nr &&
3313 page_start + offset == cluster->boundary[nr]) {
3314 set_extent_bits(&BTRFS_I(inode)->io_tree,
3315 page_start, page_end,
3320 ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
3325 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3327 btrfs_delalloc_release_extents(BTRFS_I(inode),
3330 clear_extent_bits(&BTRFS_I(inode)->io_tree,
3331 page_start, page_end,
3332 EXTENT_LOCKED | EXTENT_BOUNDARY);
3336 set_page_dirty(page);
3338 unlock_extent(&BTRFS_I(inode)->io_tree,
3339 page_start, page_end);
3344 btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
3345 balance_dirty_pages_ratelimited(inode->i_mapping);
3346 btrfs_throttle(fs_info);
3348 WARN_ON(nr != cluster->nr);
3354 static noinline_for_stack
3355 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3356 struct file_extent_cluster *cluster)
3360 if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3361 ret = relocate_file_extent_cluster(inode, cluster);
3368 cluster->start = extent_key->objectid;
3370 BUG_ON(cluster->nr >= MAX_EXTENTS);
3371 cluster->end = extent_key->objectid + extent_key->offset - 1;
3372 cluster->boundary[cluster->nr] = extent_key->objectid;
3375 if (cluster->nr >= MAX_EXTENTS) {
3376 ret = relocate_file_extent_cluster(inode, cluster);
3385 * helper to add a tree block to the list.
3386 * the major work is getting the generation and level of the block
3388 static int add_tree_block(struct reloc_control *rc,
3389 struct btrfs_key *extent_key,
3390 struct btrfs_path *path,
3391 struct rb_root *blocks)
3393 struct extent_buffer *eb;
3394 struct btrfs_extent_item *ei;
3395 struct btrfs_tree_block_info *bi;
3396 struct tree_block *block;
3397 struct rb_node *rb_node;
3402 eb = path->nodes[0];
3403 item_size = btrfs_item_size_nr(eb, path->slots[0]);
3405 if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3406 item_size >= sizeof(*ei) + sizeof(*bi)) {
3407 ei = btrfs_item_ptr(eb, path->slots[0],
3408 struct btrfs_extent_item);
3409 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3410 bi = (struct btrfs_tree_block_info *)(ei + 1);
3411 level = btrfs_tree_block_level(eb, bi);
3413 level = (int)extent_key->offset;
3415 generation = btrfs_extent_generation(eb, ei);
3416 } else if (unlikely(item_size == sizeof(struct btrfs_extent_item_v0))) {
3417 btrfs_print_v0_err(eb->fs_info);
3418 btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
3424 btrfs_release_path(path);
3426 BUG_ON(level == -1);
3428 block = kmalloc(sizeof(*block), GFP_NOFS);
3432 block->bytenr = extent_key->objectid;
3433 block->key.objectid = rc->extent_root->fs_info->nodesize;
3434 block->key.offset = generation;
3435 block->level = level;
3436 block->key_ready = 0;
3438 rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3440 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3446 * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3448 static int __add_tree_block(struct reloc_control *rc,
3449 u64 bytenr, u32 blocksize,
3450 struct rb_root *blocks)
3452 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3453 struct btrfs_path *path;
3454 struct btrfs_key key;
3456 bool skinny = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
3458 if (tree_block_processed(bytenr, rc))
3461 if (tree_search(blocks, bytenr))
3464 path = btrfs_alloc_path();
3468 key.objectid = bytenr;
3470 key.type = BTRFS_METADATA_ITEM_KEY;
3471 key.offset = (u64)-1;
3473 key.type = BTRFS_EXTENT_ITEM_KEY;
3474 key.offset = blocksize;
3477 path->search_commit_root = 1;
3478 path->skip_locking = 1;
3479 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3483 if (ret > 0 && skinny) {
3484 if (path->slots[0]) {
3486 btrfs_item_key_to_cpu(path->nodes[0], &key,
3488 if (key.objectid == bytenr &&
3489 (key.type == BTRFS_METADATA_ITEM_KEY ||
3490 (key.type == BTRFS_EXTENT_ITEM_KEY &&
3491 key.offset == blocksize)))
3497 btrfs_release_path(path);
3503 btrfs_print_leaf(path->nodes[0]);
3505 "tree block extent item (%llu) is not found in extent tree",
3512 ret = add_tree_block(rc, &key, path, blocks);
3514 btrfs_free_path(path);
3519 * helper to check if the block use full backrefs for pointers in it
3521 static int block_use_full_backref(struct reloc_control *rc,
3522 struct extent_buffer *eb)
3527 if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3528 btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3531 ret = btrfs_lookup_extent_info(NULL, rc->extent_root->fs_info,
3532 eb->start, btrfs_header_level(eb), 1,
3536 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3543 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3544 struct btrfs_block_group *block_group,
3545 struct inode *inode,
3548 struct btrfs_key key;
3549 struct btrfs_root *root = fs_info->tree_root;
3550 struct btrfs_trans_handle *trans;
3557 key.type = BTRFS_INODE_ITEM_KEY;
3560 inode = btrfs_iget(fs_info->sb, &key, root);
3565 ret = btrfs_check_trunc_cache_free_space(fs_info,
3566 &fs_info->global_block_rsv);
3570 trans = btrfs_join_transaction(root);
3571 if (IS_ERR(trans)) {
3572 ret = PTR_ERR(trans);
3576 ret = btrfs_truncate_free_space_cache(trans, block_group, inode);
3578 btrfs_end_transaction(trans);
3579 btrfs_btree_balance_dirty(fs_info);
3586 * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3587 * this function scans fs tree to find blocks reference the data extent
3589 static int find_data_references(struct reloc_control *rc,
3590 struct btrfs_key *extent_key,
3591 struct extent_buffer *leaf,
3592 struct btrfs_extent_data_ref *ref,
3593 struct rb_root *blocks)
3595 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3596 struct btrfs_path *path;
3597 struct tree_block *block;
3598 struct btrfs_root *root;
3599 struct btrfs_file_extent_item *fi;
3600 struct rb_node *rb_node;
3601 struct btrfs_key key;
3612 ref_root = btrfs_extent_data_ref_root(leaf, ref);
3613 ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3614 ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3615 ref_count = btrfs_extent_data_ref_count(leaf, ref);
3618 * This is an extent belonging to the free space cache, lets just delete
3619 * it and redo the search.
3621 if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3622 ret = delete_block_group_cache(fs_info, rc->block_group,
3623 NULL, ref_objectid);
3629 path = btrfs_alloc_path();
3632 path->reada = READA_FORWARD;
3634 root = read_fs_root(fs_info, ref_root);
3636 err = PTR_ERR(root);
3640 key.objectid = ref_objectid;
3641 key.type = BTRFS_EXTENT_DATA_KEY;
3642 if (ref_offset > ((u64)-1 << 32))
3645 key.offset = ref_offset;
3647 path->search_commit_root = 1;
3648 path->skip_locking = 1;
3649 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3655 leaf = path->nodes[0];
3656 nritems = btrfs_header_nritems(leaf);
3658 * the references in tree blocks that use full backrefs
3659 * are not counted in
3661 if (block_use_full_backref(rc, leaf))
3665 rb_node = tree_search(blocks, leaf->start);
3670 path->slots[0] = nritems;
3673 while (ref_count > 0) {
3674 while (path->slots[0] >= nritems) {
3675 ret = btrfs_next_leaf(root, path);
3680 if (WARN_ON(ret > 0))
3683 leaf = path->nodes[0];
3684 nritems = btrfs_header_nritems(leaf);
3687 if (block_use_full_backref(rc, leaf))
3691 rb_node = tree_search(blocks, leaf->start);
3696 path->slots[0] = nritems;
3700 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3701 if (WARN_ON(key.objectid != ref_objectid ||
3702 key.type != BTRFS_EXTENT_DATA_KEY))
3705 fi = btrfs_item_ptr(leaf, path->slots[0],
3706 struct btrfs_file_extent_item);
3708 if (btrfs_file_extent_type(leaf, fi) ==
3709 BTRFS_FILE_EXTENT_INLINE)
3712 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3713 extent_key->objectid)
3716 key.offset -= btrfs_file_extent_offset(leaf, fi);
3717 if (key.offset != ref_offset)
3725 if (!tree_block_processed(leaf->start, rc)) {
3726 block = kmalloc(sizeof(*block), GFP_NOFS);
3731 block->bytenr = leaf->start;
3732 btrfs_item_key_to_cpu(leaf, &block->key, 0);
3734 block->key_ready = 1;
3735 rb_node = tree_insert(blocks, block->bytenr,
3738 backref_tree_panic(rb_node, -EEXIST,
3744 path->slots[0] = nritems;
3750 btrfs_free_path(path);
3755 * helper to find all tree blocks that reference a given data extent
3757 static noinline_for_stack
3758 int add_data_references(struct reloc_control *rc,
3759 struct btrfs_key *extent_key,
3760 struct btrfs_path *path,
3761 struct rb_root *blocks)
3763 struct btrfs_key key;
3764 struct extent_buffer *eb;
3765 struct btrfs_extent_data_ref *dref;
3766 struct btrfs_extent_inline_ref *iref;
3769 u32 blocksize = rc->extent_root->fs_info->nodesize;
3773 eb = path->nodes[0];
3774 ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3775 end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3776 ptr += sizeof(struct btrfs_extent_item);
3779 iref = (struct btrfs_extent_inline_ref *)ptr;
3780 key.type = btrfs_get_extent_inline_ref_type(eb, iref,
3781 BTRFS_REF_TYPE_DATA);
3782 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3783 key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3784 ret = __add_tree_block(rc, key.offset, blocksize,
3786 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3787 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3788 ret = find_data_references(rc, extent_key,
3792 btrfs_err(rc->extent_root->fs_info,
3793 "extent %llu slot %d has an invalid inline ref type",
3794 eb->start, path->slots[0]);
3800 ptr += btrfs_extent_inline_ref_size(key.type);
3806 eb = path->nodes[0];
3807 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3808 ret = btrfs_next_leaf(rc->extent_root, path);
3815 eb = path->nodes[0];
3818 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3819 if (key.objectid != extent_key->objectid)
3822 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3823 ret = __add_tree_block(rc, key.offset, blocksize,
3825 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3826 dref = btrfs_item_ptr(eb, path->slots[0],
3827 struct btrfs_extent_data_ref);
3828 ret = find_data_references(rc, extent_key,
3830 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
3831 btrfs_print_v0_err(eb->fs_info);
3832 btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
3844 btrfs_release_path(path);
3846 free_block_list(blocks);
3851 * helper to find next unprocessed extent
3853 static noinline_for_stack
3854 int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,
3855 struct btrfs_key *extent_key)
3857 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3858 struct btrfs_key key;
3859 struct extent_buffer *leaf;
3860 u64 start, end, last;
3863 last = rc->block_group->start + rc->block_group->length;
3866 if (rc->search_start >= last) {
3871 key.objectid = rc->search_start;
3872 key.type = BTRFS_EXTENT_ITEM_KEY;
3875 path->search_commit_root = 1;
3876 path->skip_locking = 1;
3877 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3882 leaf = path->nodes[0];
3883 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3884 ret = btrfs_next_leaf(rc->extent_root, path);
3887 leaf = path->nodes[0];
3890 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3891 if (key.objectid >= last) {
3896 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3897 key.type != BTRFS_METADATA_ITEM_KEY) {
3902 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3903 key.objectid + key.offset <= rc->search_start) {
3908 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3909 key.objectid + fs_info->nodesize <=
3915 ret = find_first_extent_bit(&rc->processed_blocks,
3916 key.objectid, &start, &end,
3917 EXTENT_DIRTY, NULL);
3919 if (ret == 0 && start <= key.objectid) {
3920 btrfs_release_path(path);
3921 rc->search_start = end + 1;
3923 if (key.type == BTRFS_EXTENT_ITEM_KEY)
3924 rc->search_start = key.objectid + key.offset;
3926 rc->search_start = key.objectid +
3928 memcpy(extent_key, &key, sizeof(key));
3932 btrfs_release_path(path);
3936 static void set_reloc_control(struct reloc_control *rc)
3938 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3940 mutex_lock(&fs_info->reloc_mutex);
3941 fs_info->reloc_ctl = rc;
3942 mutex_unlock(&fs_info->reloc_mutex);
3945 static void unset_reloc_control(struct reloc_control *rc)
3947 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3949 mutex_lock(&fs_info->reloc_mutex);
3950 fs_info->reloc_ctl = NULL;
3951 mutex_unlock(&fs_info->reloc_mutex);
3954 static int check_extent_flags(u64 flags)
3956 if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3957 (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3959 if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3960 !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3962 if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3963 (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3968 static noinline_for_stack
3969 int prepare_to_relocate(struct reloc_control *rc)
3971 struct btrfs_trans_handle *trans;
3974 rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root->fs_info,
3975 BTRFS_BLOCK_RSV_TEMP);
3979 memset(&rc->cluster, 0, sizeof(rc->cluster));
3980 rc->search_start = rc->block_group->start;
3981 rc->extents_found = 0;
3982 rc->nodes_relocated = 0;
3983 rc->merging_rsv_size = 0;
3984 rc->reserved_bytes = 0;
3985 rc->block_rsv->size = rc->extent_root->fs_info->nodesize *
3986 RELOCATION_RESERVED_NODES;
3987 ret = btrfs_block_rsv_refill(rc->extent_root,
3988 rc->block_rsv, rc->block_rsv->size,
3989 BTRFS_RESERVE_FLUSH_ALL);
3993 rc->create_reloc_tree = 1;
3994 set_reloc_control(rc);
3996 trans = btrfs_join_transaction(rc->extent_root);
3997 if (IS_ERR(trans)) {
3998 unset_reloc_control(rc);
4000 * extent tree is not a ref_cow tree and has no reloc_root to
4001 * cleanup. And callers are responsible to free the above
4004 return PTR_ERR(trans);
4006 btrfs_commit_transaction(trans);
4010 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
4012 struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
4013 struct rb_root blocks = RB_ROOT;
4014 struct btrfs_key key;
4015 struct btrfs_trans_handle *trans = NULL;
4016 struct btrfs_path *path;
4017 struct btrfs_extent_item *ei;
4024 path = btrfs_alloc_path();
4027 path->reada = READA_FORWARD;
4029 ret = prepare_to_relocate(rc);
4036 rc->reserved_bytes = 0;
4037 ret = btrfs_block_rsv_refill(rc->extent_root,
4038 rc->block_rsv, rc->block_rsv->size,
4039 BTRFS_RESERVE_FLUSH_ALL);
4045 trans = btrfs_start_transaction(rc->extent_root, 0);
4046 if (IS_ERR(trans)) {
4047 err = PTR_ERR(trans);
4052 if (update_backref_cache(trans, &rc->backref_cache)) {
4053 btrfs_end_transaction(trans);
4058 ret = find_next_extent(rc, path, &key);
4064 rc->extents_found++;
4066 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
4067 struct btrfs_extent_item);
4068 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
4069 if (item_size >= sizeof(*ei)) {
4070 flags = btrfs_extent_flags(path->nodes[0], ei);
4071 ret = check_extent_flags(flags);
4073 } else if (unlikely(item_size == sizeof(struct btrfs_extent_item_v0))) {
4075 btrfs_print_v0_err(trans->fs_info);
4076 btrfs_abort_transaction(trans, err);
4082 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
4083 ret = add_tree_block(rc, &key, path, &blocks);
4084 } else if (rc->stage == UPDATE_DATA_PTRS &&
4085 (flags & BTRFS_EXTENT_FLAG_DATA)) {
4086 ret = add_data_references(rc, &key, path, &blocks);
4088 btrfs_release_path(path);
4096 if (!RB_EMPTY_ROOT(&blocks)) {
4097 ret = relocate_tree_blocks(trans, rc, &blocks);
4100 * if we fail to relocate tree blocks, force to update
4101 * backref cache when committing transaction.
4103 rc->backref_cache.last_trans = trans->transid - 1;
4105 if (ret != -EAGAIN) {
4109 rc->extents_found--;
4110 rc->search_start = key.objectid;
4114 btrfs_end_transaction_throttle(trans);
4115 btrfs_btree_balance_dirty(fs_info);
4118 if (rc->stage == MOVE_DATA_EXTENTS &&
4119 (flags & BTRFS_EXTENT_FLAG_DATA)) {
4120 rc->found_file_extent = 1;
4121 ret = relocate_data_extent(rc->data_inode,
4122 &key, &rc->cluster);
4129 if (trans && progress && err == -ENOSPC) {
4130 ret = btrfs_force_chunk_alloc(trans, rc->block_group->flags);
4138 btrfs_release_path(path);
4139 clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY);
4142 btrfs_end_transaction_throttle(trans);
4143 btrfs_btree_balance_dirty(fs_info);
4147 ret = relocate_file_extent_cluster(rc->data_inode,
4153 rc->create_reloc_tree = 0;
4154 set_reloc_control(rc);
4156 backref_cache_cleanup(&rc->backref_cache);
4157 btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
4159 err = prepare_to_merge(rc, err);
4161 merge_reloc_roots(rc);
4163 rc->merge_reloc_tree = 0;
4164 unset_reloc_control(rc);
4165 btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
4167 /* get rid of pinned extents */
4168 trans = btrfs_join_transaction(rc->extent_root);
4169 if (IS_ERR(trans)) {
4170 err = PTR_ERR(trans);
4173 btrfs_commit_transaction(trans);
4174 ret = clean_dirty_subvols(rc);
4175 if (ret < 0 && !err)
4178 btrfs_free_block_rsv(fs_info, rc->block_rsv);
4179 btrfs_free_path(path);
4183 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4184 struct btrfs_root *root, u64 objectid)
4186 struct btrfs_path *path;
4187 struct btrfs_inode_item *item;
4188 struct extent_buffer *leaf;
4191 path = btrfs_alloc_path();
4195 ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4199 leaf = path->nodes[0];
4200 item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4201 memzero_extent_buffer(leaf, (unsigned long)item, sizeof(*item));
4202 btrfs_set_inode_generation(leaf, item, 1);
4203 btrfs_set_inode_size(leaf, item, 0);
4204 btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4205 btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4206 BTRFS_INODE_PREALLOC);
4207 btrfs_mark_buffer_dirty(leaf);
4209 btrfs_free_path(path);
4214 * helper to create inode for data relocation.
4215 * the inode is in data relocation tree and its link count is 0
4217 static noinline_for_stack
4218 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4219 struct btrfs_block_group *group)
4221 struct inode *inode = NULL;
4222 struct btrfs_trans_handle *trans;
4223 struct btrfs_root *root;
4224 struct btrfs_key key;
4228 root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4230 return ERR_CAST(root);
4232 trans = btrfs_start_transaction(root, 6);
4234 return ERR_CAST(trans);
4236 err = btrfs_find_free_objectid(root, &objectid);
4240 err = __insert_orphan_inode(trans, root, objectid);
4243 key.objectid = objectid;
4244 key.type = BTRFS_INODE_ITEM_KEY;
4246 inode = btrfs_iget(fs_info->sb, &key, root);
4247 BUG_ON(IS_ERR(inode));
4248 BTRFS_I(inode)->index_cnt = group->start;
4250 err = btrfs_orphan_add(trans, BTRFS_I(inode));
4252 btrfs_end_transaction(trans);
4253 btrfs_btree_balance_dirty(fs_info);
4257 inode = ERR_PTR(err);
4262 static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4264 struct reloc_control *rc;
4266 rc = kzalloc(sizeof(*rc), GFP_NOFS);
4270 INIT_LIST_HEAD(&rc->reloc_roots);
4271 INIT_LIST_HEAD(&rc->dirty_subvol_roots);
4272 backref_cache_init(&rc->backref_cache);
4273 mapping_tree_init(&rc->reloc_root_tree);
4274 extent_io_tree_init(fs_info, &rc->processed_blocks,
4275 IO_TREE_RELOC_BLOCKS, NULL);
4280 * Print the block group being relocated
4282 static void describe_relocation(struct btrfs_fs_info *fs_info,
4283 struct btrfs_block_group *block_group)
4285 char buf[128] = {'\0'};
4287 btrfs_describe_block_groups(block_group->flags, buf, sizeof(buf));
4290 "relocating block group %llu flags %s",
4291 block_group->start, buf);
4295 * function to relocate all extents in a block group.
4297 int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
4299 struct btrfs_block_group *bg;
4300 struct btrfs_root *extent_root = fs_info->extent_root;
4301 struct reloc_control *rc;
4302 struct inode *inode;
4303 struct btrfs_path *path;
4308 bg = btrfs_lookup_block_group(fs_info, group_start);
4312 if (btrfs_pinned_by_swapfile(fs_info, bg)) {
4313 btrfs_put_block_group(bg);
4317 rc = alloc_reloc_control(fs_info);
4319 btrfs_put_block_group(bg);
4323 rc->extent_root = extent_root;
4324 rc->block_group = bg;
4326 ret = btrfs_inc_block_group_ro(rc->block_group, true);
4333 path = btrfs_alloc_path();
4339 inode = lookup_free_space_inode(rc->block_group, path);
4340 btrfs_free_path(path);
4343 ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
4345 ret = PTR_ERR(inode);
4347 if (ret && ret != -ENOENT) {
4352 rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4353 if (IS_ERR(rc->data_inode)) {
4354 err = PTR_ERR(rc->data_inode);
4355 rc->data_inode = NULL;
4359 describe_relocation(fs_info, rc->block_group);
4361 btrfs_wait_block_group_reservations(rc->block_group);
4362 btrfs_wait_nocow_writers(rc->block_group);
4363 btrfs_wait_ordered_roots(fs_info, U64_MAX,
4364 rc->block_group->start,
4365 rc->block_group->length);
4368 mutex_lock(&fs_info->cleaner_mutex);
4369 ret = relocate_block_group(rc);
4370 mutex_unlock(&fs_info->cleaner_mutex);
4375 * We may have gotten ENOSPC after we already dirtied some
4376 * extents. If writeout happens while we're relocating a
4377 * different block group we could end up hitting the
4378 * BUG_ON(rc->stage == UPDATE_DATA_PTRS) in
4379 * btrfs_reloc_cow_block. Make sure we write everything out
4380 * properly so we don't trip over this problem, and then break
4381 * out of the loop if we hit an error.
4383 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4384 ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4388 invalidate_mapping_pages(rc->data_inode->i_mapping,
4390 rc->stage = UPDATE_DATA_PTRS;
4396 if (rc->extents_found == 0)
4399 btrfs_info(fs_info, "found %llu extents", rc->extents_found);
4403 WARN_ON(rc->block_group->pinned > 0);
4404 WARN_ON(rc->block_group->reserved > 0);
4405 WARN_ON(rc->block_group->used > 0);
4408 btrfs_dec_block_group_ro(rc->block_group);
4409 iput(rc->data_inode);
4410 btrfs_put_block_group(rc->block_group);
4415 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4417 struct btrfs_fs_info *fs_info = root->fs_info;
4418 struct btrfs_trans_handle *trans;
4421 trans = btrfs_start_transaction(fs_info->tree_root, 0);
4423 return PTR_ERR(trans);
4425 memset(&root->root_item.drop_progress, 0,
4426 sizeof(root->root_item.drop_progress));
4427 root->root_item.drop_level = 0;
4428 btrfs_set_root_refs(&root->root_item, 0);
4429 ret = btrfs_update_root(trans, fs_info->tree_root,
4430 &root->root_key, &root->root_item);
4432 err = btrfs_end_transaction(trans);
4439 * recover relocation interrupted by system crash.
4441 * this function resumes merging reloc trees with corresponding fs trees.
4442 * this is important for keeping the sharing of tree blocks
4444 int btrfs_recover_relocation(struct btrfs_root *root)
4446 struct btrfs_fs_info *fs_info = root->fs_info;
4447 LIST_HEAD(reloc_roots);
4448 struct btrfs_key key;
4449 struct btrfs_root *fs_root;
4450 struct btrfs_root *reloc_root;
4451 struct btrfs_path *path;
4452 struct extent_buffer *leaf;
4453 struct reloc_control *rc = NULL;
4454 struct btrfs_trans_handle *trans;
4458 path = btrfs_alloc_path();
4461 path->reada = READA_BACK;
4463 key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4464 key.type = BTRFS_ROOT_ITEM_KEY;
4465 key.offset = (u64)-1;
4468 ret = btrfs_search_slot(NULL, fs_info->tree_root, &key,
4475 if (path->slots[0] == 0)
4479 leaf = path->nodes[0];
4480 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4481 btrfs_release_path(path);
4483 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4484 key.type != BTRFS_ROOT_ITEM_KEY)
4487 reloc_root = btrfs_read_fs_root(root, &key);
4488 if (IS_ERR(reloc_root)) {
4489 err = PTR_ERR(reloc_root);
4493 list_add(&reloc_root->root_list, &reloc_roots);
4495 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4496 fs_root = read_fs_root(fs_info,
4497 reloc_root->root_key.offset);
4498 if (IS_ERR(fs_root)) {
4499 ret = PTR_ERR(fs_root);
4500 if (ret != -ENOENT) {
4504 ret = mark_garbage_root(reloc_root);
4512 if (key.offset == 0)
4517 btrfs_release_path(path);
4519 if (list_empty(&reloc_roots))
4522 rc = alloc_reloc_control(fs_info);
4528 rc->extent_root = fs_info->extent_root;
4530 set_reloc_control(rc);
4532 trans = btrfs_join_transaction(rc->extent_root);
4533 if (IS_ERR(trans)) {
4534 unset_reloc_control(rc);
4535 err = PTR_ERR(trans);
4539 rc->merge_reloc_tree = 1;
4541 while (!list_empty(&reloc_roots)) {
4542 reloc_root = list_entry(reloc_roots.next,
4543 struct btrfs_root, root_list);
4544 list_del(&reloc_root->root_list);
4546 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4547 list_add_tail(&reloc_root->root_list,
4552 fs_root = read_fs_root(fs_info, reloc_root->root_key.offset);
4553 if (IS_ERR(fs_root)) {
4554 err = PTR_ERR(fs_root);
4558 err = __add_reloc_root(reloc_root);
4559 BUG_ON(err < 0); /* -ENOMEM or logic error */
4560 fs_root->reloc_root = reloc_root;
4563 err = btrfs_commit_transaction(trans);
4567 merge_reloc_roots(rc);
4569 unset_reloc_control(rc);
4571 trans = btrfs_join_transaction(rc->extent_root);
4572 if (IS_ERR(trans)) {
4573 err = PTR_ERR(trans);
4576 err = btrfs_commit_transaction(trans);
4578 ret = clean_dirty_subvols(rc);
4579 if (ret < 0 && !err)
4584 if (!list_empty(&reloc_roots))
4585 free_reloc_roots(&reloc_roots);
4587 btrfs_free_path(path);
4590 /* cleanup orphan inode in data relocation tree */
4591 fs_root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4592 if (IS_ERR(fs_root))
4593 err = PTR_ERR(fs_root);
4595 err = btrfs_orphan_cleanup(fs_root);
4601 * helper to add ordered checksum for data relocation.
4603 * cloning checksum properly handles the nodatasum extents.
4604 * it also saves CPU time to re-calculate the checksum.
4606 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4608 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4609 struct btrfs_ordered_sum *sums;
4610 struct btrfs_ordered_extent *ordered;
4616 ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4617 BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4619 disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4620 ret = btrfs_lookup_csums_range(fs_info->csum_root, disk_bytenr,
4621 disk_bytenr + len - 1, &list, 0);
4625 while (!list_empty(&list)) {
4626 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4627 list_del_init(&sums->list);
4630 * We need to offset the new_bytenr based on where the csum is.
4631 * We need to do this because we will read in entire prealloc
4632 * extents but we may have written to say the middle of the
4633 * prealloc extent, so we need to make sure the csum goes with
4634 * the right disk offset.
4636 * We can do this because the data reloc inode refers strictly
4637 * to the on disk bytes, so we don't have to worry about
4638 * disk_len vs real len like with real inodes since it's all
4641 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4642 sums->bytenr = new_bytenr;
4644 btrfs_add_ordered_sum(ordered, sums);
4647 btrfs_put_ordered_extent(ordered);
4651 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4652 struct btrfs_root *root, struct extent_buffer *buf,
4653 struct extent_buffer *cow)
4655 struct btrfs_fs_info *fs_info = root->fs_info;
4656 struct reloc_control *rc;
4657 struct backref_node *node;
4662 rc = fs_info->reloc_ctl;
4666 BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4667 root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4669 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4670 if (buf == root->node)
4671 __update_reloc_root(root, cow->start);
4674 level = btrfs_header_level(buf);
4675 if (btrfs_header_generation(buf) <=
4676 btrfs_root_last_snapshot(&root->root_item))
4679 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4680 rc->create_reloc_tree) {
4681 WARN_ON(!first_cow && level == 0);
4683 node = rc->backref_cache.path[level];
4684 BUG_ON(node->bytenr != buf->start &&
4685 node->new_bytenr != buf->start);
4687 drop_node_buffer(node);
4688 atomic_inc(&cow->refs);
4690 node->new_bytenr = cow->start;
4692 if (!node->pending) {
4693 list_move_tail(&node->list,
4694 &rc->backref_cache.pending[level]);
4699 __mark_block_processed(rc, node);
4701 if (first_cow && level > 0)
4702 rc->nodes_relocated += buf->len;
4705 if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4706 ret = replace_file_extents(trans, rc, root, cow);
4711 * called before creating snapshot. it calculates metadata reservation
4712 * required for relocating tree blocks in the snapshot
4714 void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
4715 u64 *bytes_to_reserve)
4717 struct btrfs_root *root = pending->root;
4718 struct reloc_control *rc = root->fs_info->reloc_ctl;
4720 if (!root->reloc_root || !rc)
4723 if (!rc->merge_reloc_tree)
4726 root = root->reloc_root;
4727 BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4729 * relocation is in the stage of merging trees. the space
4730 * used by merging a reloc tree is twice the size of
4731 * relocated tree nodes in the worst case. half for cowing
4732 * the reloc tree, half for cowing the fs tree. the space
4733 * used by cowing the reloc tree will be freed after the
4734 * tree is dropped. if we create snapshot, cowing the fs
4735 * tree may use more space than it frees. so we need
4736 * reserve extra space.
4738 *bytes_to_reserve += rc->nodes_relocated;
4742 * called after snapshot is created. migrate block reservation
4743 * and create reloc root for the newly created snapshot
4745 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4746 struct btrfs_pending_snapshot *pending)
4748 struct btrfs_root *root = pending->root;
4749 struct btrfs_root *reloc_root;
4750 struct btrfs_root *new_root;
4751 struct reloc_control *rc = root->fs_info->reloc_ctl;
4754 if (!root->reloc_root || !rc)
4757 rc = root->fs_info->reloc_ctl;
4758 rc->merging_rsv_size += rc->nodes_relocated;
4760 if (rc->merge_reloc_tree) {
4761 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4763 rc->nodes_relocated, true);
4768 new_root = pending->snap;
4769 reloc_root = create_reloc_root(trans, root->reloc_root,
4770 new_root->root_key.objectid);
4771 if (IS_ERR(reloc_root))
4772 return PTR_ERR(reloc_root);
4774 ret = __add_reloc_root(reloc_root);
4776 new_root->reloc_root = reloc_root;
4778 if (rc->create_reloc_tree)
4779 ret = clone_backref_node(trans, rc, root, reloc_root);