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[OpenStack Infra <1524035@xxxxxxxxxxxxxxxxxx>]

Reviewed:  https://review.openstack.org/260685
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=215f403ad3b7705a28075217b97a0f6f6e658204
Submitter: Jenkins
Branch:    master

commit 215f403ad3b7705a28075217b97a0f6f6e658204
Author: Matt Riedemann <mriedem@xxxxxxxxxx>
Date:   Mon Dec 21 13:48:36 2015 -0800

    DriverBlockDevice must receive a BDM object, not a dict
    
    Commit 7a54543a81cbb8d20e6df29e7f4468a436dae212
    made it such that a BlockDeviceMapping object has to be
    constructed with a request context in order to call the
    remotable save() method on it.
    
    We must be already passing BDM objects when constructing
    DriverBlockDevices otherwise calling self._bdm_obj.save()
    would fail with an OrphanedObjectError.  So the only places
    that were still using bdm dicts were unit tests, and those
    worked because objects.BlockDeviceMapping.save() is being
    mocked out.
    
    This removes the false sense of ability to construct a
    DriverBlocKDevice without a BDM object and cleans up the
    unit tests to reflect that reality.
    
    Closes-Bug: #1524035
    
    Change-Id: Ie745fc4d36ceb3e0aae1b14d5d56b2b83bbb192c


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

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https://bugs.launchpad.net/bugs/1524035

Title:
  nova.virt.block_device.DriverBlockDevice cannot save to DB if bdm
  passed in was not already an object

Status in OpenStack Compute (nova):
  Fix Released

Bug description:
  This code doesn't work:

  https://github.com/openstack/nova/blob/master/nova/virt/block_device.py#L128-L131

  That will create a BlockDeviceMapping object to be wrapped in the
  DriverBlockDevice object (if a BDM object was not passed in).  The
  problem is on self._bdm_obj.save() will fail with something like this:

  Captured traceback:
  ~~~~~~~~~~~~~~~~~~~
      Traceback (most recent call last):
        File "nova/tests/unit/virt/test_block_device.py", line 909, in test_blank_attach_volume_cinder_cross_az_attach_false
          self.virt_driver)
        File "nova/virt/block_device.py", line 456, in attach
          self.save()
        File "nova/virt/block_device.py", line 363, in save
          super(DriverVolumeBlockDevice, self).save()
        File "nova/virt/block_device.py", line 176, in save
          self._bdm_obj.save()
        File "/home/mriedem/git/nova/.tox/py27/local/lib/python2.7/site-packages/oslo_versionedobjects/base.py", line 203, in wrapper
          objtype=self.obj_name())
      oslo_versionedobjects.exception.OrphanedObjectError: Cannot call save on orphaned BlockDeviceMapping object

  That's because the BDM object that was created doesn't have a context
  set on it.

  And we can't pass context to self._bdm_obj.save() because we removed
  that here: https://review.openstack.org/#/c/164268/

  We've apparently never had a problem with this in runtime because we
  must always be constructing the DriverBlockDevice with a real BDM
  object in the compute code, we just weren't doing it properly in the
  tests - and the tests mock out nova.objects.BlockDeviceMapping.save()
  so we never knew it was a problem.

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