[PATCH] cfq-iosched: use last service point as the fairness criteria

Right now we use slice_start, which gives async queues an unfair
advantage. Chance that to service_last, and base the resorter
on that.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --cc block/cfq-iosched.c
Simple merge