* Support for multi-volume btrfs filesystems
* Support for other mkfs.btrfs options, if any are useful.
* Support for btrfs snapshots / using existing btrfs?
* Check if errors=remount-ro makes sense to use.
* mountoptions is missing a few options that may be worth supporting,
  including degraded, and all optionds that require a parameter.
* mountoptions contains nobarrier, which is an unsafe option. Remove? Warn?
* parted support needed for filesystem detection #567176
* Resizing?
* Allow forcing use of btrfs for /boot (would probably work with eg, lilo)