This obviates the need for several file system implementations to remember the device on which they are mounted. Change-Id: Ida8325cf4bcf072e61761cfee34e3f7ed2d750b9
Change-Id: Id8377873455771c614371e115643cd906d05f12c
Change-Id: Ic716f336b7071063997cf5b4dae6d50e0b4631e9