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btrfs: remove the changed list for backref cache

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Now that we're not updating the backref cache when we switch transids we
can remove the changed list.

We're going to keep the new_bytenr field because it serves as a good
sanity check for the backref cache and relocation, and can prevent us
from making extent tree corruption worse.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2024-10-03 11:43:04 -04:00 committed by David Sterba
parent 6a4730b325
commit b1d4d5d1d8
3 changed files with 8 additions and 18 deletions
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2
fs/btrfs/backref.c
View File

@ -3022,7 +3022,6 @@ void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
cache->rb_root = RB_ROOT;
for (i = 0; i < BTRFS_MAX_LEVEL; i++)
INIT_LIST_HEAD(&cache->pending[i]);
INIT_LIST_HEAD(&cache->changed);
INIT_LIST_HEAD(&cache->detached);
INIT_LIST_HEAD(&cache->leaves);
INIT_LIST_HEAD(&cache->pending_edge);
@ -3190,7 +3189,6 @@ void btrfs_backref_release_cache(struct btrfs_backref_cache *cache)
}
ASSERT(list_empty(&cache->pending_edge));
ASSERT(list_empty(&cache->useless_node));
ASSERT(list_empty(&cache->changed));
ASSERT(list_empty(&cache->detached));
ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
ASSERT(!cache->nr_nodes);

2
fs/btrfs/backref.h
View File

@ -393,8 +393,6 @@ struct btrfs_backref_cache {
struct list_head pending[BTRFS_MAX_LEVEL];
/* List of backref nodes with no child node */
struct list_head leaves;
/* List of blocks that have been COWed in current transaction */
struct list_head changed;
/* List of detached backref node. */
struct list_head detached;

22
fs/btrfs/relocation.c
View File

@ -2113,14 +2113,13 @@ struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
if (next->new_bytenr != root->node->start) {
/*
* We just created the reloc root, so we shouldn't have
* ->new_bytenr set and this shouldn't be in the changed
* list. If it is then we have multiple roots pointing
* at the same bytenr which indicates corruption, or
* we've made a mistake in the backref walking code.
* ->new_bytenr set yet. If it is then we have multiple
* roots pointing at the same bytenr which indicates
* corruption, or we've made a mistake in the backref
* walking code.
*/
ASSERT(next->new_bytenr == 0);
ASSERT(list_empty(&next->list));
if (next->new_bytenr || !list_empty(&next->list)) {
if (next->new_bytenr) {
btrfs_err(trans->fs_info,
"bytenr %llu possibly has multiple roots pointing at the same bytenr %llu",
node->bytenr, next->bytenr);
@ -2131,8 +2130,6 @@ struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
btrfs_put_root(next->root);
next->root = btrfs_grab_root(root);
ASSERT(next->root);
list_add_tail(&next->list,
&rc->backref_cache.changed);
mark_block_processed(rc, next);
break;
}
@ -2442,7 +2439,7 @@ static int do_relocation(struct btrfs_trans_handle *trans,
if (!ret && node->pending) {
btrfs_backref_drop_node_buffer(node);
list_move_tail(&node->list, &rc->backref_cache.changed);
list_del_init(&node->list);
node->pending = 0;
}
@ -2605,8 +2602,7 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
/*
* This block was the root block of a root, and this is
* the first time we're processing the block and thus it
* should not have had the ->new_bytenr modified and
* should have not been included on the changed list.
* should not have had the ->new_bytenr modified.
*
* However in the case of corruption we could have
* multiple refs pointing to the same block improperly,
@ -2616,8 +2612,7 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
* normal user in the case of corruption.
*/
ASSERT(node->new_bytenr == 0);
ASSERT(list_empty(&node->list));
if (node->new_bytenr || !list_empty(&node->list)) {
if (node->new_bytenr) {
btrfs_err(root->fs_info,
"bytenr %llu has improper references to it",
node->bytenr);
@ -2640,7 +2635,6 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
btrfs_put_root(node->root);
node->root = btrfs_grab_root(root);
ASSERT(node->root);
list_add_tail(&node->list, &rc->backref_cache.changed);
} else {
path->lowest_level = node->level;
if (root == root->fs_info->chunk_root)