yahoo-eng-team team mailing list archive

[Matt Riedemann <mriedem@xxxxxxxxxx>]

Public bug reported:

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.

** Affects: nova
     Importance: Medium
     Assignee: Matt Riedemann (mriedem)
         Status: Triaged

** Changed in: nova
       Status: New => Triaged

** Changed in: nova
   Importance: Undecided => Medium

** Changed in: nova
     Assignee: (unassigned) => Matt Riedemann (mriedem)

-- 
You received this bug notification because you are a member of Yahoo!
Engineering Team, which is subscribed to OpenStack Compute (nova).
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):
  Triaged

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.

To manage notifications about this bug go to:
https://bugs.launchpad.net/nova/+bug/1524035/+subscriptions