[PATCH] blk_execute_rq_nowait-speedup

Both elv_add_request() and generic_unplug_device() grab the queue lock
and disable interrupts, do that locally and use the __ variants.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jens Axboe <axboe@suse.de>