How to avoid data copies in a driver ?

["Francis Moreau" <francis.moro@gmail.com>]

Hello,

I'd like to optimize my driver, which receives data through a fifo and gives
them to a user space application. In turns this application moves this data
into a file.

To avoid several useless copies, I'd like the application to pass to the driver
a  file descriptor (?) to  the driver and then the driver can directly move the
received data to that file.

Could anybody give me some example of such scheme ?

Thanks,
-- 
Francis