RBD: Fix error on disconnect

On the RBD driver, when doing a disconnect call inside a container, when
the "rbd_common" package is installed on the host, we can get a "No such
file or directory" error if the udev rule from the host removes the
symlink before we do.

This error is caused by the rm command returning 1 for different type of
errors, so we'll now use -f to ensure we don't fail if the file is
missing, which is what we intended before when passing the
check_exit_code parameter to the execute call.

Trivial-Fix
Closes-Bug: #1885293
Change-Id: Id1655614a8a60fba8ed225c6cea53ae1ed4b694a

cinderlib/nos_brick.py

@@ -253,8 +253,7 @@ def unlink_root(*links, **kwargs):
     else:
         with exc.context(catch_exception, error_msg, links):
             # Ignore file doesn't exist errors
-            putils.execute('rm', *links, run_as_root=True,
-                           check_exit_code=(0, errno.ENOENT),
+            putils.execute('rm', '-f', *links, run_as_root=True,
                            root_helper=ROOT_HELPER)
 
     if not no_errors and raise_at_end and exc:

cinderlib/tests/unit/test_nos_brick.py

@@ -476,3 +476,22 @@ class TestRBDConnector(base.BaseTest):
         exec_mock.assert_called_once_with(
             'dd', 'if=/tmp/path', 'of=/dev/null', 'bs=4096', 'count=1',
             root_helper=self.connector._root_helper, run_as_root=True)
+
+    @mock.patch.object(nos_brick.os, 'unlink')
+    @mock.patch.object(nos_brick.os, 'getuid', return_value=0)
+    def test_unlink_root_being_root(self, mock_getuid, mock_unlink):
+        mock_unlink.side_effect = [None, OSError(errno.ENOENT, '')]
+        nos_brick.unlink_root(mock.sentinel.file1, mock.sentinel.file2)
+        mock_getuid.assert_called_once()
+        mock_unlink.assert_has_calls([mock.call(mock.sentinel.file1),
+                                      mock.call(mock.sentinel.file2)])
+
+    @mock.patch.object(nos_brick.putils, 'execute')
+    @mock.patch.object(nos_brick.os, 'getuid', return_value=1000)
+    def test_unlink_root_non_root(self, mock_getuid, mock_exec):
+        nos_brick.unlink_root(mock.sentinel.file1, mock.sentinel.file2)
+        mock_getuid.assert_called_once()
+        mock_exec.assert_called_once_with('rm', '-f', mock.sentinel.file1,
+                                          mock.sentinel.file2,
+                                          run_as_root=True,
+                                          root_helper=nos_brick.ROOT_HELPER)

releasenotes/notes/rbd-missing-file-or-directory-c835abac22f6b32e.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fix issue where disconnecting an RBD volume inside a container when the
+    host had the ceph-common package installed could lead to failure due to a
+    "No such file or directory" error.
+    (Bug #1885293).