On Wed 01-02-23 20:06:09, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> After commit dfd6200a0954 ("blk-cgroup: support to track if policy is
> online"), there is no need to do this again in bfq.
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
So I agree this is nice to do but it isn't so simple. BFQ relies on the
fact that 'online' is cleared under bfqd->lock so we cannot associate bio
in bfq_bio_bfqg() with a bfqg that has already its bfq_pd_offline()
function run.
Maybe if you set 'online' to false before calling ->pd_offline() things
would work fine for BFQ.
Honza
> ---
> block/bfq-cgroup.c | 4 +---
> block/bfq-iosched.h | 2 --
> 2 files changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
> index b42956ab5550..a35136dae713 100644
> --- a/block/bfq-cgroup.c
> +++ b/block/bfq-cgroup.c
> @@ -551,7 +551,6 @@ static void bfq_pd_init(struct blkg_policy_data *pd)
> bfqg->bfqd = bfqd;
> bfqg->active_entities = 0;
> bfqg->num_queues_with_pending_reqs = 0;
> - bfqg->online = true;
> bfqg->rq_pos_tree = RB_ROOT;
> }
>
> @@ -614,7 +613,7 @@ struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio)
> continue;
> }
> bfqg = blkg_to_bfqg(blkg);
> - if (bfqg->online) {
> + if (bfqg->pd.online) {
> bio_associate_blkg_from_css(bio, &blkg->blkcg->css);
> return bfqg;
> }
> @@ -985,7 +984,6 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
>
> put_async_queues:
> bfq_put_async_queues(bfqd, bfqg);
> - bfqg->online = false;
>
> spin_unlock_irqrestore(&bfqd->lock, flags);
> /*
> diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
> index 75cc6a324267..69aaee52285a 100644
> --- a/block/bfq-iosched.h
> +++ b/block/bfq-iosched.h
> @@ -1009,8 +1009,6 @@ struct bfq_group {
>
> /* reference counter (see comments in bfq_bic_update_cgroup) */
> refcount_t ref;
> - /* Is bfq_group still online? */
> - bool online;
>
> struct bfq_entity entity;
> struct bfq_sched_data sched_data;
> --
> 2.31.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
