If the loop partition isn't created as a device by the kernel, go
ahead and use kpartx to create the device.

Change-Id: I53290b7724d0cb45a1fc9225ec096025db8978dd
Remove a device mapping, then let the loop device get removed

Change-Id: Ie1eb621ff56688208421d0115547f127a3c7fd56
Call sync before unmounting keeps the mount from being busy.

Change-Id: I9d5a1f092fd8f3ae1c14de03dd516203baab4da3