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[OpenStack Infra <1803961@xxxxxxxxxxxxxxxxxx>]

Reviewed:  https://review.opendev.org/637224
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=53c3cfa7a02d684ce27800e22e00a816af44c510
Submitter: Zuul
Branch:    master

commit 53c3cfa7a02d684ce27800e22e00a816af44c510
Author: Lee Yarwood <lyarwood@xxxxxxxxxx>
Date:   Fri Feb 15 16:26:23 2019 +0000

    Use migration_status during volume migrating and retyping
    
    When swapping volumes Nova has to identify if the swap itself is related
    to an underlying migration or retype of the volume by Cinder.  Nova
    would previously use the status of the volume to determine if the volume
    was retyping or migrating.
    
    However in the migration case where a volume is moved directly between
    hosts the volume is never given a status  of migrating by Cinder leading
    to Nova never calling the os-migrate_volume_completion cinder API to
    complete the migration.
    
    This change switches Nova to use the migration_status of the volume to
    ensure that this API is called for both retypes and migrations.
    
    Depends-On: https://review.openstack.org/#/c/639331/
    Change-Id: I1bdf3431bda2da98380e0dcaa9f952e6768ca3af
    Closes-bug: #1803961


** Changed in: nova
       Status: In Progress => Fix Released

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https://bugs.launchpad.net/bugs/1803961

Title:
  Nova doesn't call migrate_volume_completion after cinder volume
  migration

Status in OpenStack Compute (nova):
  Fix Released

Bug description:
  Originally reported in Red Hat Bugzilla:
  https://bugzilla.redhat.com/show_bug.cgi?id=1648931

  Create a cinder volume, attach it to a nova instance, and migrate the
  volume to a different storage host:

  $ cinder create 1 --volume-type foo --name myvol
  $ nova volume-attach myinstance myvol
  $ cinder migrate myvol c-vol2

  Everything seems to work correctly, but if we look at myinstance we
  see that it's now connected to a new volume, and the original volume
  is still present on the original storage host.

  This is because nova didn't call cinder's migrate_volume_completion.
  migrate_volume_completion would have deleted the original volume, and
  changed the volume id of the new volume to be the same as the
  original. The result would be that myinstance would appear to be
  connected to the same volume as before.

  Note that there are 2 ways (that I'm aware of) to intiate a cinder
  volume migration: retype and migrate. AFAICT retype is *not* affected.
  In fact, I updated the relevant tempest test to try to trip it up and
  it didn't fail. However, an exlicit migrate *is* affected. They are
  different top-level entry points in cinder, and set different state,
  which is what triggers the Nova bug.

  This appears to be a regression which was introduced by
  https://review.openstack.org/#/c/456971/ :

          # Yes this is a tightly-coupled state check of what's going on inside
          # cinder, but we need this while we still support old (v1/v2) and
          # new style attachments (v3.44). Once we drop support for old style
          # attachments we could think about cleaning up the cinder-initiated
          # swap volume API flows.
          is_cinder_migration = (
              True if old_volume['status'] in ('retyping',
                                               'migrating') else False)

  There's a bug here because AFAICT cinder never sets status to
  'migrating' during any operation: it sets migration_status to
  'migrating' during both retype and migrate. During retype it sets
  status to 'retyping', but not during an explicit migrate.

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