Add the ability to extend npiv volumes

The compute host does not need to do anything for the client to
see the extended size.

Depends-on: I0f6f80df6ad0d87dcccc560509c4e31992e4c0ec
Change-Id: I94aa12d422fe6c38a3ab8f7e37489738c956fb6f

doc/source/support-matrix.ini

@@ -105,7 +105,8 @@ notes=The extend volume operation provides a means to extend
   Therefore this operation is not considered to be mandatory to support.
 cli=cinder extend <volume> <new_size>
 driver-impl-powervm=partial
-driver-notes-powervm=Extend volume only supported for fileio and iSCSI volumes.
+driver-notes-powervm=Extend volume only supported for NPIV, FileIO, and iSCSI
+  volumes.
 
 [operation.maintenance-mode]
 title=Set the host in a maintenance mode

nova_powervm/tests/virt/powervm/volume/test_npiv.py

@@ -194,6 +194,10 @@ class TestNPIVAdapter(test_vol.TestVolumeAdapter):
         self.vol_drv.instance.system_metadata = {meta_st_key: fabric_state,
                                                  meta_fb_key: meta_fb_map}
 
+    def test_extend_volume(self):
+        # Ensure the method is implemented
+        self.vol_drv.extend_volume()
+
     @mock.patch('pypowervm.tasks.vfc_mapper.remove_maps')
     @mock.patch('pypowervm.tasks.vfc_mapper.find_vios_for_vfc_wwpns')
     def test_disconnect_volume(self, mock_find_vios, mock_remove_maps):

nova_powervm/virt/powervm/volume/npiv.py

@@ -77,6 +77,11 @@ class NPIVVolumeAdapter(v_driver.FibreChannelVolumeAdapter):
         for fabric in self._fabric_names():
             self._add_maps_for_fabric(fabric, slot_mgr)
 
+    def extend_volume(self):
+        # The compute node does not need to take any additional steps for the
+        # client to see the extended volume.
+        pass
+
     def _disconnect_volume(self, slot_mgr):
         """Disconnect the volume.