Here's a much better version.  The real bug was of course that the
get_user/put_user for data_direction were transposed.

This patch also fixes the translation of "quiet" and "timeout" to be
safer and clearer (instead of memcpying them as two ints and knowing
that "quiet" is first and assuming that "compat_int_t" is always the
same as the native "int", the code now handles them explicitly).

We should use "access_ok()" and __get_user/__put_user to generate better
code for this, but it's not performance-critical, so we don't care.
Some other day, perhaps.