luks / encrypted volume can not be closed

[Phillip Susi]

If you install ubuntu with the default full disk encryption option, it creates a partition as a luks container holding an lvm physical volume, which holds two logical volumes: one for root and one for swap. If you boot the livecd, it shows an encrypted disk icon on the unity launcher. Clicking this icon prompts for the luks password and then opens it, and the lvm inside is automatically mounted. The encrypted physical volume vanishes from the unity launcher and the contained root partition is auto mounted. Unmounting this partition still leaves the luks volume unlocked so you can remount it without having to supply the encryption password.

Using the gnome disks utility to unlock the luks volume causes it to show up as if it is a sub-partition of the luks partition, and trying to click the lock icon to close the luks volume results in a giant error dialog because it is in use by the lvm volumes. It should be smart enough to deactivate the vg contained in the luks volume so it can then deactivate the luks volume.