Fix

mount-notify_test.c: In function ‘fanotify_rmdir’:
mount-notify_test.c:467:17: 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 an error is reported.

Fixes: e1c24b52adb22 ("selftests: add tests for mount notification")
Cc: Miklos Szeredi <mszeredi@redhat.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.c     | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c
index e4b7c2b457ee..5c929275e689 100644
--- a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c
+++ b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c
@@ -464,7 +464,8 @@ TEST_F(fanotify, rmdir)
 	ASSERT_GE(ret, 0);
 
 	if (ret == 0) {
-		chdir("/");
+		if (chdir("/"))
+			perror("chdir()");
 		unshare(CLONE_NEWNS);
 		mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL);
 		umount2("/a", MNT_DETACH);
-- 
2.45.2