Add attribute 'name' to class RBDVolume.

If we create backup for volume  in-use, volume
driver will clone a temporary volume, and create
a snapshot based on the temporary volume, then
create backup for the snapshot. So, the src_name
passed to method _rbd_diff_transfer should be the
name of the temporary volume instead of the original
volume's name. In order to get this name, we need
add self.name to class os_brick.initiator.linuxrbd.
RBDVolume, that's because ceph provides rbd.so to
cinder, but we can't get volume name from rbd.Image
directly.

Co-Authored-By: Ivan Kolodyazhny <e0ne@e0ne.info>
Change-Id: Ic2732e985b75ae710da3814c2d5b2253ced74534
Closes-Bug: #1663504

os_brick/initiator/linuxrbd.py

@@ -110,6 +110,11 @@ class RBDVolume(object):
             client.disconnect()
             raise
 
+        # Ceph provides rbd.so to cinder, but we can't
+        # get volume name from rbd.Image, so, we record
+        # name here, so other modules can easily get
+        # volume name.
+        self.name = name
         self.client = client
 
     def close(self):

os_brick/tests/initiator/test_linuxrbd.py

@@ -156,3 +156,10 @@ class RBDVolumeIOWrapperTestCase(base.TestCase):
             linuxrbd.RBDImageMetadata(rbd_volume, 'pool', 'user', None))
         rbd_handle.close()
         self.assertEqual(1, rbd_disconnect.call_count)
+
+
+class RBDVolumeTestCase(base.TestCase):
+    def test_name_attribute(self):
+        mock_client = mock.Mock()
+        rbd_volume = linuxrbd.RBDVolume(mock_client, 'volume')
+        self.assertEqual('volume', rbd_volume.name)