Merge "Leverage the iSCSI mpath to get the WWN" into stable/train

os_brick/initiator/connectors/iscsi.py

@@ -737,7 +737,7 @@ class ISCSIConnector(base.BaseLinuxConnector, base_iscsi.BaseISCSIConnector):
                     data['failed_logins'])):
             # We have devices but we don't know the wwn yet
             if not wwn and found:
-                wwn = self._linuxscsi.get_sysfs_wwn(found)
+                wwn = self._linuxscsi.get_sysfs_wwn(found, mpath)
             if not mpath and found:
                 mpath = self._linuxscsi.find_sysfs_multipath_dm(found)
                 # We have the wwn but not a multipath
@@ -778,6 +778,8 @@ class ISCSIConnector(base.BaseLinuxConnector, base_iscsi.BaseISCSIConnector):
         if not mpath:
             LOG.warning('No dm was created, connection to volume is probably '
                         'bad and will perform poorly.')
+        elif not wwn:
+            wwn = self._linuxscsi.get_sysfs_wwn(found, mpath)
         return self._get_connect_result(connection_properties, wwn, found,
                                         mpath)
 

os_brick/initiator/linuxscsi.py

@@ -119,8 +119,20 @@ class LinuxSCSI(executor.Executor):
 
         return dev_info
 
-    def get_sysfs_wwn(self, device_names):
+    def get_sysfs_wwn(self, device_names, mpath=None):
         """Return the wwid from sysfs in any of devices in udev format."""
+        # If we have a multipath DM we know that it has found the WWN
+        if mpath:
+            # We have the WWN in /uuid even with friendly names, unline /name
+            try:
+                with open('/sys/block/%s/dm/uuid' % mpath) as f:
+                    # Contents are matph-WWN, so get the part we want
+                    wwid = f.read().strip()[6:]
+                    if wwid:  # Check should not be needed, but just in case
+                        return wwid
+            except Exception as exc:
+                LOG.warning('Failed to read the DM uuid: %s', exc)
+
         wwid = self.get_sysfs_wwid(device_names)
         glob_str = '/dev/disk/by-id/scsi-'
         wwn_paths = glob.glob(glob_str + '*')

os_brick/tests/initiator/connectors/test_iscsi.py

@@ -1206,6 +1206,8 @@ Setting up iSCSI targets: unused
         result = list(get_wwn_mock.call_args[0][0])
         result.sort()
         self.assertEqual(['sda', 'sdb', 'sdc', 'sdd'], result)
+        # Check we pass the mpath
+        self.assertIsNone(get_wwn_mock.call_args[0][1])
         add_wwid_mock.assert_called_once_with('wwn')
         self.assertNotEqual(0, add_path_mock.call_count)
         self.assertGreaterEqual(find_dm_mock.call_count, 2)
@@ -1238,10 +1240,13 @@ Setting up iSCSI targets: unused
                     'path': '/dev/dm-0'}
         self.assertEqual(expected, res)
 
-        self.assertGreaterEqual(get_wwn_mock.call_count, 2)
+        self.assertGreaterEqual(get_wwn_mock.call_count, 3)
         result = list(get_wwn_mock.call_args[0][0])
         result.sort()
         self.assertEqual(['sda', 'sdb', 'sdc', 'sdd'], result)
+        # Initially mpath we pass is None, but on last call is the mpath
+        mpath_values = [c[1][1] for c in get_wwn_mock._mock_mock_calls]
+        self.assertEqual([None, None, 'dm-0'], mpath_values[0:3])
         add_wwid_mock.assert_not_called()
         add_path_mock.assert_not_called()
         self.assertGreaterEqual(find_dm_mock.call_count, 2)

os_brick/tests/initiator/test_linuxscsi.py

@@ -848,6 +848,16 @@ loop0                                     0"""
         mock_exec.assert_called_once_with(
             'multipathd', 'show', 'status', run_as_root=True, root_helper=None)
 
+    @mock.patch('six.moves.builtins.open')
+    def test_get_sysfs_wwn_mpath(self, open_mock):
+        wwn = '3600d0230000000000e13955cc3757800'
+        cm_open = open_mock.return_value.__enter__.return_value
+        cm_open.read.return_value = 'mpath-' + wwn
+
+        res = self.linuxscsi.get_sysfs_wwn(mock.sentinel.device_names, 'dm-1')
+        open_mock.assert_called_once_with('/sys/block/dm-1/dm/uuid')
+        self.assertEqual(wwn, res)
+
     @mock.patch('glob.glob')
     @mock.patch.object(linuxscsi.LinuxSCSI, 'get_sysfs_wwid')
     def test_get_sysfs_wwn_single_designator(self, get_wwid_mock, glob_mock):
@@ -859,6 +869,20 @@ loop0                                     0"""
         glob_mock.assert_called_once_with('/dev/disk/by-id/scsi-*')
         get_wwid_mock.assert_called_once_with(mock.sentinel.device_names)
 
+    @mock.patch('six.moves.builtins.open', side_effect=Exception)
+    @mock.patch('glob.glob')
+    @mock.patch.object(linuxscsi.LinuxSCSI, 'get_sysfs_wwid')
+    def test_get_sysfs_wwn_mpath_exc(self, get_wwid_mock, glob_mock,
+                                     open_mock):
+        glob_mock.return_value = ['/dev/disk/by-id/scsi-wwid1',
+                                  '/dev/disk/by-id/scsi-wwid2']
+        get_wwid_mock.return_value = 'wwid1'
+        res = self.linuxscsi.get_sysfs_wwn(mock.sentinel.device_names, 'dm-1')
+        open_mock.assert_called_once_with('/sys/block/dm-1/dm/uuid')
+        self.assertEqual('wwid1', res)
+        glob_mock.assert_called_once_with('/dev/disk/by-id/scsi-*')
+        get_wwid_mock.assert_called_once_with(mock.sentinel.device_names)
+
     @mock.patch('os.listdir', return_value=['sda', 'sdd'])
     @mock.patch('os.path.realpath', side_effect=('/other/path',
                                                  '/dev/dm-5',