Description of problem:

After the release of "Newton", we have reinstalled the Centos 7 servers with it and it seems there is a bug on creating snapshots which was not present on the previous version.

We are using a NFS and everything works except the snapshot creation of an instance.

The snapshot is created in the dashboard UI but it has 0 bytes.



Cinder versions :

openstack-cinder-9.0.0-1.el7.noarch
python-cinder-9.0.0-1.el7.noarch
puppet-cinder-9.4.1-1.el7.noarch
python2-cinderclient-1.9.0-1.el7.noarch



Errors in the logs :

As you can see, everything works until a snapshot creation is issues :

2016-10-24 12:58:45.614 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 12:59:45.610 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 13:00:45.610 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 13:01:45.605 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 13:02:45.606 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 13:03:45.604 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 13:04:45.607 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 13:05:45.603 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 13:06:45.605 864 INFO os_brick.remotefs.remotefs [req-89cc603d-924e-4792-b4d0-7bf2e414d64f - - - - -] Already mounted: /var/lib/cinder/mnt/cbeb33711a066b92c69af055294191cb
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server [req-c3b6d825-8f16-4d89-8c42-61e93c8163d1 bb753d3055be44e7a94a8cf3ace3dde4 e0546923a5544605bed01036f20dff37 - default default] Exception during message handling
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server Traceback (most recent call last):
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/server.py", line 133, in _process_incoming
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server     res = self.dispatcher.dispatch(message)
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 150, in dispatch
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server     return self._do_dispatch(endpoint, method, ctxt, args)
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 121, in _do_dispatch
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server     result = func(ctxt, **new_args)
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/cinder/volume/manager.py", line 4376, in create_snapshot
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server     snapshot)
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/cinder/volume/manager.py", line 850, in create_snapshot
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server     snapshot.save()
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server     self.force_reraise()
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server     six.reraise(self.type_, self.value, self.tb)
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/cinder/volume/manager.py", line 842, in create_snapshot
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server     model_update = self.driver.create_snapshot(snapshot)
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server AttributeError: 'NfsDriver' object has no attribute 'create_snapshot'
2016-10-24 13:07:20.047 864 ERROR oslo_messaging.rpc.server 



How reproducible:

Openstack newton with NFS as a storage.

Steps to Reproduce:
1. Create an instance
2. Issue a create snapshot
3. Snapshot created with 0 bytes

Actual results:

No snapshot and log errors ( posted above )

Expected results:

Obtain a usable snapshot

Additional info:

Please let me know if more info is needed.

Thank you guys for all the great work you have done with the project.