[PATCH 5.18 733/879] bfq: Track whether bfq_group is still online

Greg Kroah-Hartman
2022-06-08T01:41:31Z

From: Jan Kara <jack@suse.cz>

commit 09f871868080c33992cd6a9b72a5ca49582578fa upstream.

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.

CC: stable@vger.kernel.org
Tested-by: "yukuai (C)" <yukuai3@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220401102752.8599-7-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
block/bfq-cgroup.c | 3 ++-
block/bfq-iosched.h | 2 ++
2 files changed, 4 insertions(+), 1 deletion(-)

--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -557,6 +557,7 @@ static void bfq_pd_init(struct blkg_poli
*/
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(str
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_p

put_async_queues:
bfq_put_async_queues(bfqd, bfqg);
+ bfqg->online = false;

spin_unlock_irqrestore(&bfqd->lock, flags);
/*
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -929,6 +929,8 @@ 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;