yahoo-eng-team team mailing list archive

[Nikola Đipanov <ndipanov@xxxxxxxxxx>]

Public bug reported:

THis came up when analyzing https://bugs.launchpad.net/nova/+bug/1371677
and there is a lot information on there. The bug in short is that
_get_instance_disk_info will rely on db information to filter out the
volumes from the list of discs it gets from libvirt XML, but due to the
async nature of unplug - this can still contain a volume that does not
exist in the DB and will not be filtered out, so the code will assume
it's an lvm image and do a blockdev on it which can block for a very
long time.

The solution is to NOT use libvirt XML in this particular case (but
anywhere in Nova really) to find out information about running
instances.

** Affects: nova
     Importance: High
         Status: New


** Tags: libvirt

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https://bugs.launchpad.net/bugs/1375868

Title:
  libvirt: race between hot unplug and XMLDesc in
  _get_instance_disk_info

Status in OpenStack Compute (Nova):
  New

Bug description:
  THis came up when analyzing
  https://bugs.launchpad.net/nova/+bug/1371677 and there is a lot
  information on there. The bug in short is that _get_instance_disk_info
  will rely on db information to filter out the volumes from the list of
  discs it gets from libvirt XML, but due to the async nature of unplug
  - this can still contain a volume that does not exist in the DB and
  will not be filtered out, so the code will assume it's an lvm image
  and do a blockdev on it which can block for a very long time.

  The solution is to NOT use libvirt XML in this particular case (but
  anywhere in Nova really) to find out information about running
  instances.

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