block, bfq: put reqs of waker and woken in dispatch list

block, bfq: put reqs of waker and woken in dispatch list

Consider a new I/O request that arrives for a bfq_queue bfqq. If, when
this happens, the only active bfq_queues are bfqq and either its waker
bfq_queue or one of its woken bfq_queues, then there is no point in
queueing this new I/O request in bfqq for service. In fact, the
in-service queue and bfqq agree on serving this new I/O request as
soon as possible. So this commit puts this new I/O request directly
into the dispatch list.

Tested-by: Jan Kara <[email protected]>
Acked-by: Jan Kara <[email protected]>
Signed-off-by: Paolo Valente <[email protected]>
Tested-by: Oleksandr Natalenko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>