qemu-img convert should be skipped when migrating.

[Hiroyuki Eguchi]

Currently, qemu image is always converted when resizing and migrating.

Image conversion is done for migrate complete qcow2 image.

But, It is unnecessary to merge the backing file in case of a shared storage environment.
It's needed in case of a non shared storage environment. but _create_image() in finish_migration() tries to download backing file.

So We can skip qemu-img conversion in both cases.

I have modified so that nova-compute just copy the file instead of conversion.

The qemu-img convert is IO heavy process, so I'd like to skip, if possible.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/138979

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/139001

[OpenStack Infra (hudson-openstack)]

Change abandoned by Hiroyuki Eguchi (<email address hidden>) on branch: master
Review: https://review.openstack.org/139001
Reason: duplicate ticket

[Hiroyuki Eguchi (h-eguchi)]

Cloud you please review this ?

Review: https://review.openstack.org/138979

[Davanum Srinivas (DIMS) (dims-v)]

Fix proposed in https://review.openstack.org/138979 is in progress

[OpenStack Infra (hudson-openstack)]

Change abandoned by Joe Gordon (<email address hidden>) on branch: master
Review: https://review.openstack.org/138979
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Hiroyuki Eguchi (h-eguchi)]

I have addded the new review ticket.

Review : https://review.openstack.org/194516/

[OpenStack Infra (hudson-openstack)]

Change abandoned by Hiroyuki Eguchi (<email address hidden>) on branch: master
Review: https://review.openstack.org/194516
Reason: Duplicate of https://review.openstack.org/#/c/138979/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/138979
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=1319c89555b7671f8e7df5cf85d5d4df1dbaba5e
Submitter: Jenkins
Branch: master

commit 1319c89555b7671f8e7df5cf85d5d4df1dbaba5e
Author: Hiroyuki Eguchi <email address hidden>
Date: Wed Aug 5 15:46:17 2015 +0900

    libvirt: qemu-img convert should be skipped when migrating

    Image conversion is done to migrate the complete qcow2 image.
    But, it is unnecessary to merge the backing file.
    I have modified so that nova-compute just copy
    the file instead of conversion.
    It is possible to move the file in case of
    a shared storage environment, but nova resize-revert
    fails in that case.

    Closes-Bug: #1399098
    Change-Id: Ic05b48761f09a4711a11bacfc64cbcf39b352e84