Make sure that make_create_in_sticky() never sees uninitialized value of dir_mode

make sure nd->dir_mode is always initialized after success exit from
link_path_walk(); in case of empty path it did not happen.
Reported-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
Tested-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -2114,8 +2114,10 @@ static int link_path_walk(const char *name, struct nameidata *nd)
 		return PTR_ERR(name);
 	while (*name=='/')
 		name++;
-	if (!*name)
+	if (!*name) {
+		nd->dir_mode = 0; // short-circuit the 'hardening' idiocy
 		return 0;
+	}
 
 	/* At this point we know we have a real path component. */
 	for(;;) {