[PATCH 5.17 633/772] bfq: Track whether bfq_group is still online

[Greg Kroah-Hartman]

From: Jan Kara <jack@xxxxxxx>

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@xxxxxxxxxxxxxxx
Tested-by: "yukuai (C)" <yukuai3@xxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/20220401102752.8599-7-jack@xxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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;
 
@@ -971,6 +971,7 @@ 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
@@ -930,6 +930,8 @@ 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;