blk-iocost: track whether iocg is still online

hulk inclusion
category: bugfix
bugzilla: 188107, https://gitee.com/openeuler/kernel/issues/I665S2
CVE: NA

--------------------------------

blkcg_gq->online can't be used in iocost because it get cleared only after
all policies are offlined. This patch add a new field 'online' in iocg.
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Signed-off-by: NLi Nan <linan122@huawei.com>

block/blk-iocost.c

@@ -486,6 +486,7 @@ struct ioc_gq {
 	u32				inuse;
 
 	u32				last_inuse;
+	bool				online;
 	s64				saved_margin;
 
 	sector_t			cursor;		/* to detect randio */
@@ -2932,6 +2933,7 @@ static void ioc_pd_init(struct blkg_policy_data *pd)
 	ioc_now(ioc, &now);
 
 	iocg->ioc = ioc;
+	iocg->online = true;
 	atomic64_set(&iocg->vtime, now.vnow);
 	atomic64_set(&iocg->done_vtime, now.vnow);
 	atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));
@@ -2966,6 +2968,8 @@ static void ioc_pd_offline(struct blkg_policy_data *pd)
 	if (ioc) {
 		spin_lock_irqsave(&ioc->lock, flags);
 
+		iocg->online = false;
+
 		if (!list_empty(&iocg->active_list)) {
 			struct ioc_now now;