blk-ioc: don't hold queue_lock for ioc_lookup_icq()

Currently issue io can grab queue_lock three times from bfq_bio_merge(),
bfq_limit_depth() and bfq_prepare_request(), the queue_lock is not
necessary if icq is already created because both queue and ioc can't be
freed before io issuing is done, hence remove the unnecessary queue_lock
and use rcu to protect radix tree lookup.

Noted this is also a prep patch to support request batch dispatching[1].

[1] https://lore.kernel.org/all/[email protected]/

Signed-off-by: Yu Kuai <[email protected]>
Reviewed-by: Damien Le Moal <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions