xapi live migration rollback should clean up any volume attached during migration

[Sulochan Acharya]

When live migrating an instance with volume attached the volume gets attached to the destination during the process. If after that there is a failure, the volume is left attachd to the destination, and then gets attached to the source.

Source cleanup is explicit, however, we do not do any cleanup during rollback for xapi on live migration failure.

We need to simply forget the sr as a part of migration rollback.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/217105

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/217105
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ca342f2048993718718a7a7435ca88b9469c9220
Submitter: Jenkins
Branch: master

commit ca342f2048993718718a7a7435ca88b9469c9220
Author: Sulochan Acharya <email address hidden>
Date: Wed Aug 26 12:02:56 2015 +0000

    xapi: cleanup volume sr on live migration rollback

    On the destination we currently attach any volume
    that a live migrating instance might have, however,
    when an error occurs after the volume attach, the rollback
    does not clean it up, leaving the volume on destination.

    This patch simply ensures that sr_forget is called for
    any bdm that an instance might have.

    Also, fixes xapi test to not use None as dbm param
    for live migration rollback, since bdm cant be None
    here.

    Change-Id: I23c5bf4aa44c65e12f0403450b4c7c37dee648ce
    Closes-bug: #1488884