[PATCH] Improve CD/DVD packet driver write performance

This patch improves write performance for the CD/DVD packet writing driver.
 The logic for switching between reading and writing has been changed so
that streaming writes are no longer interrupted by read requests.

Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>