It's invalid if the given mode is neither dir nor link, so warn on else
case.

Link: http://lkml.kernel.org/r/20160812024754.12352.8536.stgit@pluto.themaw.netSigned-off-by: NTomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: NIan Kent <raven@themaw.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>