Re: [PATCH v2 12/13] selftests/fs/mount-notify-ns: Fix build warning

Fix

mount-notify_test_ns.c: In function ‘fanotify_rmdir’:
mount-notify_test_ns.c:494:17: warning:
        ignoring return value of ‘chdir’ declared with attribute ‘warn_unused_result’

by checking the return value of chdir() and displaying an error message
if it returns an error.

Fixes: 781091f3f5945 ("selftests/fs/mount-notify: add a test variant running inside userns")
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: Update subject and description to reflect that the patch fixes a build
    warning.
    Use perror() to display an error message if chdir() returns an error.

 .../selftests/filesystems/mount-notify/mount-notify_test_ns.c  | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c
index 9f57ca46e3af..90bec6faf64e 100644
--- a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c
+++ b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c

@@ -491,7 +491,8 @@ TEST_F(fanotify, rmdir)
        ASSERT_GE(ret, 0);

        if (ret == 0) {
-               chdir("/");
+               if (chdir("/"))
+                       perror("chdir()");