LVM clear_volume should raise exc. if volume_clear opt is invalid

[Eric Harney]

Currently if a user configures volume_clear='non_existent_volume_clearer' in cinder.conf, the LVM driver will silently delete a volume and not wipe it.

Instead, the delete operation should fail, leaving the volume in the 'error_deleting' state. This prevents a user from believing their volumes are being wiped when they are not due to misconfiguration.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/46572

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/46572
Committed: http://github.com/openstack/cinder/commit/863ae9f484089aa5d9e576255b39288da82c1100
Submitter: Jenkins
Branch: master

commit 863ae9f484089aa5d9e576255b39288da82c1100
Author: Eric Harney <email address hidden>
Date: Fri Sep 13 16:56:44 2013 -0400

    LVM volume_clear: error on unexpected inputs

    Currently if a user configures
    volume_clear='non_existent_volume_clearer' in cinder.conf,
    the LVM driver will silently delete a volume and not wipe it.

    Instead, the delete operation should fail, leaving the volume
    in the 'error_deleting' state.

    Also fail if the volume reference does not contain either a
    'size' or 'volume_size' field.

    Closes-Bug: #1225194
    Change-Id: I78fec32d7d5aeaa8e2deeac43066ca5e2e26d9ca