Fix cinder volume transfer

Change-Id: I9f843f04fb7a7613cb1b274a969bb71bda8e9564

rally-jobs/cinder.yaml

@@ -353,6 +353,37 @@
               users_per_tenant: 3
     {% endfor %}
 
+    -
+      title: CinderVolumes.create_and_accept_transfer tests
+      workloads:
+        -
+          scenario:
+            CinderVolumes.create_and_accept_transfer:
+              size: 1
+          runner:
+            constant:
+              times: 2
+              concurrency: 2
+          contexts:
+            users:
+              tenants: 2
+              users_per_tenant: 2
+        -
+          description: "Create volume from image and accept transfer."
+          scenario:
+            CinderVolumes.create_and_accept_transfer:
+              size: 1
+              image:
+                name: {{image_name}}
+          runner:
+            constant:
+              times: 2
+              concurrency: 2
+          contexts:
+            users:
+              tenants: 2
+              users_per_tenant: 2
+
     -
       title: CinderVolumes.create_and_extend_volume tests
       workloads:

rally_openstack/services/storage/cinder_common.py

@@ -475,10 +475,14 @@ class UnifiedCinderMixin(object):
 
     @staticmethod
     def _unify_transfer(transfer):
-        auth_key = transfer.auth_key if hasattr(transfer, "auth_key") else None
-        return block.VolumeTransfer(id=transfer.id, name=transfer.name,
+        return block.VolumeTransfer(
+            id=transfer.id,
+            name=transfer.name,
             volume_id=transfer.volume_id,
-                                    auth_key=auth_key)
+            # NOTE(andreykurilin): we need to access private field to avoid
+            #   calling extra GET request when the object is not not fully
+            #   loaded.
+            auth_key=transfer._info.get("auth_key"))
 
     @staticmethod
     def _unify_qos(qos):