xtensa_pipe() for xtensa.
Signed-off-by: WANG Cong <amwang@redhat.com>
Reviewed-by: Johannes Weiner <jw@emlix.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>