sch_sfb: keep backlog updated with qlen

Fixes: 2ccccf5fb43f ("net_sched: update hierarchical backlog too")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_sfb.c

@@ -400,6 +400,7 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 enqueue:
 	ret = qdisc_enqueue(skb, child, to_free);
 	if (likely(ret == NET_XMIT_SUCCESS)) {
+		qdisc_qstats_backlog_inc(sch, skb);
 		sch->q.qlen++;
 		increment_qlen(skb, q);
 	} else if (net_xmit_drop_count(ret)) {
@@ -428,6 +429,7 @@ static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
 
 	if (skb) {
 		qdisc_bstats_update(sch, skb);
+		qdisc_qstats_backlog_dec(sch, skb);
 		sch->q.qlen--;
 		decrement_qlen(skb, q);
 	}
@@ -450,6 +452,7 @@ static void sfb_reset(struct Qdisc *sch)
 	struct sfb_sched_data *q = qdisc_priv(sch);
 
 	qdisc_reset(q->qdisc);
+	sch->qstats.backlog = 0;
 	sch->q.qlen = 0;
 	q->slot = 0;
 	q->double_buffering = false;