XenAPI: Workaround for 6.5 iSCSI bug

XenServer 6.5 doesn't handle iSCSI connections correctly, due to a bug
introduced when changing the backend support.
This has been fixed upstream for the next version of XenServer, but
fix in Nova as well to ensure users of 6.5 can use Cinder-provided
volumes

Change-Id: I74e690228690d42e247f948e8be8e82ba1bf4c5b
Closes-bug: 1502929
(cherry picked from commit 46c55399c0)
Depends-On: Iefa5b16a3fa1789ed583426ea47ebb22e6cb571e

nova/tests/unit/virt/xenapi/test_volume_utils.py

@@ -241,6 +241,38 @@ class FindVBDTestCase(stubs.XenAPITestBaseNoDB):
         session.VBD.get_userdevice.assert_called_once_with("a")
 
 
+class IntroduceSRTestCase(stubs.XenAPITestBaseNoDB):
+    @mock.patch.object(volume_utils, '_create_pbd')
+    def test_backend_kind(self, create_pbd):
+        session = mock.Mock()
+        session.product_version = (6, 5, 0)
+        session.call_xenapi.return_value = 'sr_ref'
+        params = {'sr_type': 'iscsi'}
+        sr_uuid = 'sr_uuid'
+        label = 'label'
+        expected_params = {'backend-kind': 'vbd'}
+
+        volume_utils.introduce_sr(session, sr_uuid, label, params)
+        session.call_xenapi.assert_any_call('SR.introduce', sr_uuid,
+                                            label, '', 'iscsi',
+                                            '', False, expected_params)
+
+    @mock.patch.object(volume_utils, '_create_pbd')
+    def test_backend_kind_upstream_fix(self, create_pbd):
+        session = mock.Mock()
+        session.product_version = (7, 0, 0)
+        session.call_xenapi.return_value = 'sr_ref'
+        params = {'sr_type': 'iscsi'}
+        sr_uuid = 'sr_uuid'
+        label = 'label'
+        expected_params = {}
+
+        volume_utils.introduce_sr(session, sr_uuid, label, params)
+        session.call_xenapi.assert_any_call('SR.introduce', sr_uuid,
+                                            label, '', 'iscsi',
+                                            '', False, expected_params)
+
+
 class BootedFromVolumeTestCase(stubs.XenAPITestBaseNoDB):
     def test_booted_from_volume(self):
         session = mock.Mock()

nova/virt/xenapi/volume_utils.py

@@ -27,6 +27,7 @@ from eventlet import greenthread
 from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_utils import strutils
+from oslo_utils import versionutils
 
 from nova import exception
 from nova.i18n import _, _LE, _LW
@@ -132,6 +133,9 @@ def introduce_sr(session, sr_uuid, label, params):
 
     sr_type, sr_desc = _handle_sr_params(params)
 
+    if _requires_backend_kind(session.product_version) and sr_type == 'iscsi':
+        params['backend-kind'] = 'vbd'
+
     sr_ref = session.call_xenapi('SR.introduce', sr_uuid, label, sr_desc,
             sr_type, '', False, params)
 
@@ -145,6 +149,12 @@ def introduce_sr(session, sr_uuid, label, params):
     return sr_ref
 
 
+def _requires_backend_kind(version):
+    # Fix for Bug #1502929
+    version_as_string = '.'.join(str(v) for v in version)
+    return (versionutils.is_compatible('6.5', version_as_string))
+
+
 def _handle_sr_params(params):
     if 'id' in params:
         del params['id']