On Wed, Feb 12, 2020 at 03:43:31PM +0800, Qu Wenruo wrote: > 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. > > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> Added to misc-next, thanks.
