From f996674c36fe1a109853d88113e27b44a7a5cf45 Mon Sep 17 00:00:00 2001
From: melanie witt <melwittt@gmail.com>
Date: Wed, 10 Aug 2022 23:22:47 +0000
Subject: [PATCH] Fix exception catch when volume mount fails

When we call nova.privsep.fs.mount(), we are catching
ProcessExecutionError() (an instance of a class) and that is not allowed
in python3.

This changes the except statement to catch ProcessExecutionError
(class) instead.

Closes-Bug: #1984736

Change-Id: I24a269f9809063f864a4f0443d6724dfa8703d9d
---
 .../unit/virt/libvirt/volume/test_mount.py    | 26 +++++++++++++++++++
 nova/virt/libvirt/volume/mount.py             |  2 +-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/nova/tests/unit/virt/libvirt/volume/test_mount.py b/nova/tests/unit/virt/libvirt/volume/test_mount.py
index 8ecb117f05..a27505052f 100644
--- a/nova/tests/unit/virt/libvirt/volume/test_mount.py
+++ b/nova/tests/unit/virt/libvirt/volume/test_mount.py
@@ -580,6 +580,32 @@ class HostMountStateTestCase(test.NoDBTestCase):
 
         mock_log.assert_called()
 
+    @mock.patch.object(mount.LOG, 'exception')
+    def test_mount_failure(self, mock_log_exc):
+        m = self._get_clean_hostmountstate()
+        err = processutils.ProcessExecutionError
+        self.mock_mount.side_effect = err
+
+        # Mount vol_a
+        self.assertRaises(err, self._sentinel_mount, m, mock.sentinel.vol_a)
+
+        # Verify the mountpoint got removed after the failure
+        self.assertEqual({}, m.mountpoints)
+
+        # Now try a scenario where the mount failed because the volume was
+        # already mounted
+        self.mock_ismount.side_effect = [False, True]
+
+        # Mount vol_a
+        self._sentinel_mount(m, mock.sentinel.vol_a)
+
+        # Verify the mountpoint is present despite the error
+        self.assertEqual(1, len(m.mountpoints))
+        self.assertIn(mock.sentinel.mountpoint, m.mountpoints)
+
+        # Verify we logged an exception
+        mock_log_exc.assert_called()
+
 
 class MountManagerTestCase(test.NoDBTestCase):
     class FakeHostMountState(object):
diff --git a/nova/virt/libvirt/volume/mount.py b/nova/virt/libvirt/volume/mount.py
index d85ac8aa48..01338497b6 100644
--- a/nova/virt/libvirt/volume/mount.py
+++ b/nova/virt/libvirt/volume/mount.py
@@ -306,7 +306,7 @@ class _HostMountState(object):
 
                 try:
                     nova.privsep.fs.mount(fstype, export, mountpoint, options)
-                except processutils.ProcessExecutionError():
+                except processutils.ProcessExecutionError:
                     # Check to see if mountpoint is mounted despite the error
                     # eg it was already mounted
                     if os.path.ismount(mountpoint):