Comment 8 for bug 1937084

Reviewed: https://review.opendev.org/c/openstack/nova/+/812127
Committed: https://opendev.org/openstack/nova/commit/067cd93424ea1e62c77744986a5479d1b99b0ffe
Submitter: "Zuul (22348)"
Branch: master

commit 067cd93424ea1e62c77744986a5479d1b99b0ffe
Author: Lee Yarwood <email address hidden>
Date: Fri Oct 1 12:21:57 2021 +0100

    block_device: Ignore VolumeAttachmentNotFound during detach

    Bug #1937084 details a race condition within Cinder where requests to
    delete an attachment and later delete the underlying volume can race
    leading to the initial request returning a 404 if the volume delete
    completes first.

    This change attempts to handle this within Nova during a detach as we
    ultimately don't care that the volume and/or volume attachment are no
    longer available within Cinder. This allows Nova to complete its' own
    cleanup of the BlockDeviceMapping record resulting in the volume no
    longer appearing attached in Nova's APIs.

    Closes-Bug: #1937084

    Change-Id: I191552652d8ff5206abad7558c99bce27979dc84