Hello,

this adds a bio write queue congestion control
to the pktcdvd driver with fixed on/off marks.
It prevents that the driver consumes a unlimited
amount of write requests.

Needs this patch named:
[PATCH 1/2] 2.6.19-rc2-mm1 ll_rw_blk.c: export clear_queue_congested and set_queue_congested

I hope this code is ok now ;)
(Maybe the surrounding spin_locks can be removed,
but for atomic access to bio_write_size etc., they may
be a good thing...)

Signed-off-by: Thomas Maier <balagi@justmail.de>