Ignore empty NPIV fabrics on disconnect

A spawn may roll back all operations within the flow, even if the
execute has not yet run against them.  This means that a disconnect
volume may occur before a connect volume if something in the flow failed
before the volume actions.

Currently, the vSCSI flow is prepared for this.  However, the NPIV path
would fail.

This change set resolves the disconnect to tolerate empty fabrics on a
disconnect.  It will detect if a fabric has not yet been connected and
log accordingly on the disconnect.

Change-Id: I78c51fa3677d78d28f1efd66a29394a24538e145
Closes-Bug: 1493940

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

@@ -199,6 +199,22 @@ class TestNPIVAdapter(test.TestCase):
         self.assertEqual(2, mock_remove_maps.call_count)
         self.assertEqual(1, self.ft_fx.patchers['update'].mock.call_count)
 
+    @mock.patch('pypowervm.tasks.vfc_mapper.remove_maps')
+    @mock.patch('nova_powervm.virt.powervm.volume.npiv.NPIVVolumeAdapter.'
+                '_get_fabric_meta')
+    def test_disconnect_volume_no_fabric_meta(self, mock_get_fabric_meta,
+                                              mock_remove_maps):
+        # Mock Data.  The fabric_names is set to A by setUp.
+        # Force a None return
+        self.vol_drv.instance.task_state = 'deleting'
+        mock_get_fabric_meta.return_value = []
+
+        # Invoke
+        self.vol_drv.disconnect_volume()
+
+        # No mappings should have been removed
+        self.assertFalse(mock_remove_maps.called)
+
     @mock.patch('nova_powervm.virt.powervm.volume.npiv.NPIVVolumeAdapter.'
                 '_remove_maps_for_fabric')
     def test_disconnect_volume_no_op(self, mock_remove_maps):

nova_powervm/virt/powervm/volume/npiv.py

@@ -19,7 +19,7 @@ from oslo_log import log as logging
 from taskflow import task
 
 from nova.compute import task_states
-from nova.i18n import _LI
+from nova.i18n import _LI, _LW
 from pypowervm.tasks import vfc_mapper as pvm_vfcm
 from pypowervm.wrappers import virtual_io_server as pvm_vios
 
@@ -380,6 +380,10 @@ class NPIVVolumeAdapter(v_driver.FibreChannelVolumeAdapter):
         :param fabric: The fabric to remove the mappings from.
         """
         npiv_port_maps = self._get_fabric_meta(fabric)
+        if not npiv_port_maps:
+            # If no mappings exist, exit out of the method.
+            return
+
         vios_wraps = self.stg_ftsk.feed
 
         for npiv_port_map in npiv_port_maps:
@@ -474,7 +478,13 @@ class NPIVVolumeAdapter(v_driver.FibreChannelVolumeAdapter):
         """
         meta_key = self._sys_meta_fabric_key(fabric)
         if self.instance.system_metadata.get(meta_key) is None:
-            return None
+            # If no mappings exist, log a warning.
+            LOG.warn(_LW("No NPIV mappings exist for instance %(inst)s on "
+                         "fabric %(fabric)s.  May not have connected to "
+                         "the fabric yet or fabric configuration was recently "
+                         "modified."),
+                     {'inst': self.instance.name, 'fabric': fabric})
+            return []
 
         meta_value = self.instance.system_metadata[meta_key]
         wwpns = meta_value.split(",")