[IBM DS8000] Fixed Detach for multi-attach volumes

During detach operation for Multi attach type volumes
the first detach from the host is successful.
In the second detach operation the volume remains in
detaching state.

Fixed the above issue by adding a check for multi-attach
volumes and get the host mapping info of a volume.
If the volume is attached to multiple hosts, then skip
the delete host operation and return.

Closes-bug: #1951046

Change-Id: I8f4586292d1310d6f7bd9fd22b98715f3414d23c

cinder/volume/drivers/ibm/ibm_storage/ds8k_helper.py

@@ -678,7 +678,8 @@ class DS8KCommonHelper(object):
         }
 
     @coordination.synchronized('ibm-ds8k-{connector[host]}')
-    def terminate_connection(self, vol_id, host_id, connector, map_info):
+    def terminate_connection(self, volume, vol_id, host_id, connector,
+                             map_info):
         host = self._get_host(connector)
         host_ports = map_info['host_ports']
         lun_ids = map_info['lun_ids']
@@ -690,6 +691,27 @@ class DS8KCommonHelper(object):
                   {"host": host_ports,
                    "defined": host_id,
                    "delete": delete_ports})
+        host_name = host.name
+        if (host.name[:7] == "OShost:"):
+            host_name = host.name[7:]
+        attachment_count = 0
+        if hasattr(volume, 'multiattach') and volume.multiattach:
+            try:
+                attachment_list = volume.volume_attachment
+                for attachment in attachment_list:
+                    if (attachment.attach_status == "attached" and
+                       attachment.attached_host == host_name):
+                        attachment_count += 1
+            except AttributeError:
+                pass
+        if attachment_count > 1:
+            LOG.info("Volume %(volume)s is attached to multiple "
+                     "instances on host %(host)s, hence "
+                     "skipping delete host.",
+                     {'volume': volume.name,
+                      'host': host.name})
+            return
+
         for lun_id in lun_ids:
             self._delete_mappings(host_id, lun_id)
         if not lun_ids:
@@ -1263,7 +1285,8 @@ class DS8KECKDHelper(DS8KCommonHelper):
             }
         }
 
-    def terminate_connection(self, vol_id, connector, force, **kwargs):
+    def terminate_connection(self, volume, vol_id, connector, force,
+                             **kwargs):
         return None
 
 

cinder/volume/drivers/ibm/ibm_storage/ds8k_proxy.py

@@ -1113,8 +1113,9 @@ class DS8KProxy(proxy.IBMStorageProxy):
             backend_helper = self._helper
         if isinstance(backend_helper, helper.DS8KECKDHelper):
             LOG.info('Detach the volume %s.', lun.ds_id)
-            return backend_helper.terminate_connection(lun.ds_id, connector,
-                                                       force, **kwargs)
+            return backend_helper.terminate_connection(volume, lun.ds_id,
+                                                       connector, force,
+                                                       **kwargs)
         else:
             vol_mapped, host_id, map_info = (
                 backend_helper.check_vol_mapped_to_host(connector, lun.ds_id))
@@ -1155,11 +1156,13 @@ class DS8KProxy(proxy.IBMStorageProxy):
                     else:
                         LOG.info('Detach the volume %s.', lun.replica_ds_id)
                         return backend_helper.terminate_connection(
-                            lun.replica_ds_id, host_id, connector, map_info)
+                            volume, lun.replica_ds_id, host_id, connector,
+                            map_info)
             elif host_id and vol_mapped:
                 LOG.info('Detaching volume %s.', lun.ds_id)
-                return backend_helper.terminate_connection(lun.ds_id, host_id,
-                                                           connector, map_info)
+                return backend_helper.terminate_connection(volume, lun.ds_id,
+                                                           host_id, connector,
+                                                           map_info)
 
     @proxy.logger
     def create_group(self, ctxt, group):

releasenotes/notes/bug-1951046-ds8k_fixed_detach_for_multi_attach_volumes-b86940efafa926f2.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    IBM DS8000 Driver `Bug #1951046
+    <https://bugs.launchpad.net/cinder/+bug/1951046>`_:
+    Fixed detach issue for multi-attach volumes. Detach
+    the volume without deleting the host until attachment
+    count is zero.