Call driver for attach/detach_volume.

The volume driver may want to know which guest is going to be
attached to a volume. The manager now calls down into the driver
on attach_volume and detach_volume.

Fixes bug 1038109.

Change-Id: I084c2d09a1871fa158312f9ba479abb474da1d28

cinder/volume/driver.py

@@ -234,6 +234,14 @@ def terminate_connection(self, volume, connector):
         """Disallow connection from connector"""
         raise NotImplementedError()
 
+    def attach_volume(self, context, volume_id, instance_uuid, mountpoint):
+        """ Callback for volume attached to instance."""
+        pass
+
+    def detach_volume(self, context, volume_id):
+        """ Callback for volume detached."""
+        pass
+
     def get_volume_stats(self, refresh=False):
         """Return the current state of the volume service. If 'refresh' is
            True, run the update first."""

cinder/volume/manager.py

@@ -257,6 +257,17 @@ def attach_volume(self, context, volume_id, instance_uuid, mountpoint):
         if not utils.is_uuid_like(instance_uuid):
             raise exception.InvalidUUID(instance_uuid)
 
+        try:
+            self.driver.attach_volume(context,
+                                      volume_id,
+                                      instance_uuid,
+                                      mountpoint)
+        except Exception:
+            with excutils.save_and_reraise_exception():
+                self.db.volume_update(context,
+                                      volume_id,
+                                      {'status': 'error_attaching'})
+
         self.db.volume_attached(context.elevated(),
                                 volume_id,
                                 instance_uuid,
@@ -266,6 +277,14 @@ def detach_volume(self, context, volume_id):
         """Updates db to show volume is detached"""
         # TODO(vish): refactor this into a more general "unreserve"
         # TODO(sleepsonthefloor): Is this 'elevated' appropriate?
+        try:
+            self.driver.detach_volume(context, volume_id)
+        except Exception:
+            with excutils.save_and_reraise_exception():
+                self.db.volume_update(context,
+                                      volume_id,
+                                      {'status': 'error_detaching'})
+
         self.db.volume_detached(context.elevated(), volume_id)
 
     def _copy_image_to_volume(self, context, volume, image_id):