[PATCH 7/9] bfq: Track whether bfq_group is still online

Jan Kara
2022-03-30T12:47:30Z

Track whether bfq_group is still online. We cannot rely on
blkcg_gq->online because that gets cleared only after all policies are
offlined and we need something that gets updated already under
bfqd->lock when we are cleaning up our bfq_group to be able to guarantee
that when we see online bfq_group, it will stay online while we are
holding bfqd->lock lock.

Signed-off-by: Jan Kara <jack@suse.cz>
---
block/bfq-cgroup.c | 3 ++-
block/bfq-iosched.h | 2 ++
2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 9352f3cc2377..879380c2bc7e 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -557,6 +557,7 @@ static void bfq_pd_init(struct blkg_policy_data *pd)
*/
bfqg->bfqd = bfqd;
bfqg->active_entities = 0;
+ bfqg->online = true;
bfqg->rq_pos_tree = RB_ROOT;
}

@@ -603,7 +604,6 @@ struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
struct bfq_entity *entity;

bfqg = bfq_lookup_bfqg(bfqd, blkcg);
-
if (unlikely(!bfqg))
return NULL;

@@ -979,6 +979,7 @@ 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 a56763045d19..4664e2f3e828 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -928,6 +928,8 @@ struct bfq_group {

/* reference counter (see comments in bfq_bic_update_cgroup) */
int ref;
+ /* Is bfq_group still online? */
+ bool online;

struct bfq_entity entity;
struct bfq_sched_data sched_data;
--
2.34.1