block, bfq: make bfq_has_work() more accurate

mainline inclusion
from mainline-v5.19-rc1
commit ddc25c86
category: bugfix
bugzilla: 186769, https://gitee.com/openeuler/kernel/issues/I5FYJY


CVE: NA

--------------------------------

bfq_has_work() is using busy_queues currently, which is not accurate
because bfq_queue is busy doesn't represent that it has requests. Since
bfqd aready has a counter 'queued' to record how many requests are in
bfq, use it instead of busy_queues.

Noted that bfq_has_work() can be called with 'bfqd->lock' held, thus the
lock can't be held in bfq_has_work() to protect 'bfqd->queued'.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220513023507.2625717-3-yukuai3@huawei.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>