Comment 4 for bug 1060893

And about the btrfs subvolume handling. Currently you must have @ as root volume. And that also means you will only be able to have on ubuntu/debian based system installed on btrfs.

See:
https://help.ubuntu.com/community/btrfs#The_btrfs-tools_command_.27.27set-default.27.27_will_break_Ubuntu.27s_layout