Very Computer

I have a linux driver for a Host Bus Adapter.  The maximum IO transfer size
that it receives from linux version 2.4.2-2 kernel is 32 kB.   The IO
transfer size seems to be controlled by variable "request_bufflen".  The
maximum value this variable can take is set perhaps somewhere in
/usr/src/linux-2.4.2/drivers/scsi.  I need to know where this variable is
set so I can change it to a higher value.  I don't think this is a file
system problem because this limit is there even when my program reads/writes
to a raw device.