btrfs: relocation: Remove is_cowonly_root()

This function is only used in read_fs_root(), which is just a wrapper of
btrfs_get_fs_root().

For all the mentioned essential roots except log root tree,
btrfs_get_fs_root() has its own quick path to grab them from fs_info
directly, thus no need for key.offset modification.

For subvolume trees, btrfs_get_fs_root() with key.offset == -1 is
completely fine.

For log trees and log root tree, it's impossible to hit them, as for
relocation all backrefs are fetched from commit root, which never
records log tree blocks.

Log tree blocks either get freed in regular transaction commit, or
replayed at mount time. At runtime we should never hit an backref for
log tree in extent tree.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2020-02-12 15:43:31 +08:00 committed by David Sterba
parent fe119a6eeb
commit e19221180d
1 changed files with 1 additions and 19 deletions

View File

@ -640,21 +640,6 @@ static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
return btrfs_grab_root(root);
}
static int is_cowonly_root(u64 root_objectid)
{
if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
root_objectid == BTRFS_DEV_TREE_OBJECTID ||
root_objectid == BTRFS_TREE_LOG_OBJECTID ||
root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
root_objectid == BTRFS_UUID_TREE_OBJECTID ||
root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
return 1;
return 0;
}
static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
u64 root_objectid)
{
@ -662,10 +647,7 @@ static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
key.objectid = root_objectid;
key.type = BTRFS_ROOT_ITEM_KEY;
if (is_cowonly_root(root_objectid))
key.offset = 0;
else
key.offset = (u64)-1;
key.offset = (u64)-1;
return btrfs_get_fs_root(fs_info, &key, false);
}