btrfs: relocation: Remove is_cowonly_root() (e1922118) · Commits · 戴 / test

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>

fs/btrfs/relocation.c

+1 −19

Original line number	Diff line number	Diff line
		@@ -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)
		{
		@@ -662,9 +647,6 @@ 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;

		return btrfs_get_fs_root(fs_info, &key, false);

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