cinder backup api don't support the backup of in-use volume if cinder backupend is nfs and cinder backup backupend is nfs too

[mylq]

cinder backup api don't support the backup of in-use volume if cinder backupend is nfs and cinder backup backupend is nfs too.
Here is the code in https://github.com/openstack/cinder/blob/master/cinder/backup/api.py line 202-231:
    def create(self, context, name, description, volume_id,
               container, incremental=False, availability_zone=None,
               force=False, snapshot_id=None):
        """Make the RPC call to create a volume backup."""
        check_policy(context, 'create')
        volume = self.volume_api.get(context, volume_id)
        snapshot = None
        if snapshot_id:
            snapshot = self.volume_api.get_snapshot(context, snapshot_id)

            if volume_id != snapshot.volume_id:
                msg = (_('Volume %(vol1)s does not match with '
                         'snapshot.volume_id %(vol2)s.')
                       % {'vol1': volume_id,
                          'vol2': snapshot.volume_id})
                raise exception.InvalidVolume(reason=msg)
        if volume['status'] not in ["available", "in-use"]:
            msg = (_('Volume to be backed up must be available '
                     'or in-use, but the current status is "%s".')
                   % volume['status'])
            raise exception.InvalidVolume(reason=msg)
        elif volume['status'] in ["in-use"] and not snapshot_id and not force:
            msg = _('Backing up an in-use volume must use '
                    'the force flag.')
            raise exception.InvalidVolume(reason=msg)
        elif snapshot_id and snapshot['status'] not in ["available"]:
            msg = (_('Snapshot to be backed up must be available, '
                     'but the current status is "%s".')
                   % snapshot['status'])
            raise exception.InvalidSnapshot(reason=msg)

Infact,if the cinder volume backupend is nfs not lvm,it would be wrong if you backup a in-use volume to a nfs backup backupend.

[Sean McGinnis (sean-mcginnis)]

Unassigning due to no activity for > 6 months.