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[OpenStack Infra <1552303@xxxxxxxxxxxxxxxxxx>]

Reviewed:  https://review.openstack.org/287363
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=4378b4fa43aa966aee8ddee77d5220e9c4476b5a
Submitter: Jenkins
Branch:    master

commit 4378b4fa43aa966aee8ddee77d5220e9c4476b5a
Author: Pawel Koniszewski <pawel.koniszewski@xxxxxxxxx>
Date:   Fri Mar 11 16:32:21 2016 +0100

    Use migrate_data.block_migration instead of block_migration
    
    Since nova can calculate block_migration we might end up with
    a case where block_migration is None while migrate_data.block_migration
    is True.
    
    Both drivers that support block live migration, Libvirt and Xenapi,
    use migrate_data.block_migration already, so we should switch to use
    it everywhere, instead of in drivers only.
    
    Change-Id: Iaa8aea3cb58ed0864a6a38d4a163649f52e32c5c
    Closes-Bug: #1552303


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

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https://bugs.launchpad.net/bugs/1552303

Title:
  Block live migrations are broken when nova calculates live migration
  type by itself

Status in OpenStack Compute (nova):
  Fix Released

Bug description:
  All block live migrations are broken when I want nova to calculate
  live migration type by specifying {'block_migration': 'auto'} in
  request body. This happens because block_migration and
  migrate_data.block_migration flags do not have the same value.

  In conductor live migrate task we call checks on destination and
  source that builds up migrate_data in driver and sends them back to
  conductor:

  https://github.com/openstack/nova/blob/master/nova/conductor/tasks/live_migrate.py#L156

  Here we calculate block migration, this is fine:

  https://github.com/openstack/nova/blob/master/nova/virt/libvirt/driver.py#L5554

  Then it goes back to conductor and we call compute manager sending
  both flags - block_migration and migrate_data.block_migration - but we
  never change value of block_migration to match
  migrate_data.block_migration:

  https://github.com/openstack/nova/blob/master/nova/conductor/tasks/live_migrate.py#L68

  Because down in compute manager (and in drivers) we use both flags
  that have different values (here block_migration=None,
  migrate_data.block_migration=True), e.g. at this point
  block_migration=None:

  https://github.com/openstack/nova/blob/master/nova/compute/manager.py#L5196

  We break all block live migrations with:

  Traceback (most recent call last):
    File "/usr/local/lib/python2.7/dist-packages/eventlet/hubs/hub.py", line 457, in fire_timers
      timer()
    File "/usr/local/lib/python2.7/dist-packages/eventlet/hubs/timer.py", line 58, in __call__
      cb(*args, **kw)
    File "/usr/local/lib/python2.7/dist-packages/eventlet/event.py", line 168, in _do_send
      waiter.switch(result)
    File "/usr/local/lib/python2.7/dist-packages/eventlet/greenthread.py", line 214, in main
      result = function(*args, **kwargs)
    File "/opt/stack/nova/nova/utils.py", line 1160, in context_wrapper
      return func(*args, **kwargs)
    File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 6095, in _live_migration_operation
      instance=instance)
    File "/usr/local/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
      self.force_reraise()
    File "/usr/local/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
      six.reraise(self.type_, self.value, self.tb)
    File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 6063, in _live_migration_operation
      CONF.libvirt.live_migration_bandwidth)
    File "/usr/local/lib/python2.7/dist-packages/eventlet/tpool.py", line 186, in doit
      result = proxy_call(self._autowrap, f, *args, **kwargs)
    File "/usr/local/lib/python2.7/dist-packages/eventlet/tpool.py", line 144, in proxy_call
      rv = execute(f, *args, **kwargs)
    File "/usr/local/lib/python2.7/dist-packages/eventlet/tpool.py", line 125, in execute
      six.reraise(c, e, tb)
    File "/usr/local/lib/python2.7/dist-packages/eventlet/tpool.py", line 83, in tworker
      rv = meth(*args, **kwargs)
    File "/usr/local/lib/python2.7/dist-packages/libvirt.py", line 1825, in migrateToURI2
      if ret == -1: raise libvirtError ('virDomainMigrateToURI2() failed', dom=self)
  libvirtError: Cannot access storage file '/opt/stack/data/nova/instances/572ad149-b7c5-4b77-85b5-34c1d2d37fcf/disk' (as uid:110, gid:116): No such file or directory

  Fast workaround is making sure at compute manager level that
  block_migration == migrate_data.block_migration, but really we should
  cleanup all this mess and send only one flag, because it is error-
  prone and hard to maintain.

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