This new algorithm adds support for wiping volumes using TRIM.

It does not overwrite all the data in a volume, but it tells the
backing storage pool/driver that all bytes in a volume can be
discarded.

It depends on the backing storage pool how this is handled.

A SCSI backend might send UNMAP commands to remove all data present
on a LUN.

A Ceph backend might use rbd_discard() to instruct the Ceph cluster
that all data on that RBD volume can be discarded.
Signed-off-by: NWido den Hollander <wido@widodh.nl>