blk-mq: add blk_mq_delay_queue

Add a blk-mq equivalent to blk_delay_queue so that the scsi layer can ask
to be kicked again after a delay.

Signed-off-by: Christoph Hellwig <[email protected]>

Modified by me to kill the unnecessary preempt disable/enable
in the delayed workqueue handler.

Signed-off-by: Jens Axboe <[email protected]>
3 files changed