Comment 6 for bug 1853495

Reviewed: https://review.opendev.org/696683
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=059dc01ae027f00ffffbaa9ee8a3c958031829ce
Submitter: Zuul
Branch: stable/train

commit 059dc01ae027f00ffffbaa9ee8a3c958031829ce
Author: Lee Yarwood <email address hidden>
Date: Fri Nov 15 09:57:27 2019 +0000

    block_device: Copy original volume_type when missing for snapshot based volumes

    Attempts to launch an instance from an encrypted volume snapshot would
    previously fail if a volume_type was not specified in the
    block_device_mapping of the boot request.

    To avoid such failures DriverVolSnapshotBlockDevice will now attempt to
    lookup and use the volume_type of the original volume that the snapshot
    is based on. This should allow the eventual volume creation request
    based on the snapshot to succeed in cases where a volume_type is
    required but not provided in the boot request.

    Conflicts:
            nova/virt/block_device.py

    NOTE(lyarwood): Due to I30a49c9e085cffc071d0ba332db67945e116bc80 not
    being present in stable/train.

    Closes-Bug: #1853495
    Change-Id: Ic749c49e227e41732dbe04acea303b303acd264a
    (cherry picked from commit 5679a0bf99c17ff336fa520c9cdfad5156c6c9d2)