pre_live_migration is missing some disk information in case of block migration

[Thomas Herve]

The pre_live_migration API is called with a disk retrieved by a call to driver.get_instance_disk_info when doing a block migration. Unfortunately block device information is not passed, so Nova is calling LibvirtDriver._create_images_and_backing with partial disk_info.

As a result, for example when migrating a volume with a NFS volume attached, a useless file is created in the instance directory.

[Florent Flament (florentflament)]

Hi Thomas, well I think the bug impact is much worse. After migration, the VM uses a local copy of the "shared" volume. This is very bad, since any data written on the volume will be discarded once the VM has been destroyed.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/125574

[Florent Flament (florentflament)]

My mistake. Once the VM has been migrated, it still uses the "shared" volume. The useless file created is not used. Still, this is bug.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: stable/icehouse
Review: https://review.openstack.org/126223

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/125574
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=8489e4a2d100fa34f49a044f1973a163a4bfb8e5
Submitter: Jenkins
Branch: master

commit 8489e4a2d100fa34f49a044f1973a163a4bfb8e5
Author: Thomas Herve <email address hidden>
Date: Thu Oct 2 09:25:50 2014 +0200

    Pass block device info in pre_live_migration

    In case of block migration, this adds block device information to the
    disk information handled by pre_live_migration, so that at least in the
    case of libvirt no spurious files are created corresponding to volumes.

    Co-Authored-By: <email address hidden>
    Change-Id: I373001e0ef0e4fe4ab900d399756f27101cfe5c8
    Closes-Bug: 1376586

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean Dague (<email address hidden>) on branch: stable/icehouse
Review: https://review.openstack.org/126223
Reason: This review is > 4 weeks without comment and currently blocked by a core reviewer with a -2. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and contacting the reviewer with the -2 on this review to ensure you address their concerns.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/189213

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/189213
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=79b2b9427d5e016894b58d3e208c5f445195ab2f
Submitter: Jenkins
Branch: stable/juno

commit 79b2b9427d5e016894b58d3e208c5f445195ab2f
Author: Thomas Herve <email address hidden>
Date: Thu Oct 2 09:25:50 2014 +0200

    Pass block device info in pre_live_migration

    In case of block migration, this adds block device information to the
    disk information handled by pre_live_migration, so that at least in the
    case of libvirt no spurious files are created corresponding to volumes.

    (cherry picked from commit 8489e4a2d100fa34f49a044f1973a163a4bfb8e5)

    Co-Authored-By: <email address hidden>
    Change-Id: I373001e0ef0e4fe4ab900d399756f27101cfe5c8
    Closes-Bug: 1376586