bfq: Extract bfq_group_set_weight from bfq_io_set_weight_legacy

This function will be useful when we update weight from the soon-coming
per-device interface.
Signed-off-by: Fam Zheng <zhengfeiran@bytedance.com>
Reviewed-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bfq-cgroup.c

@@ -919,34 +919,16 @@ static int bfq_io_show_weight(struct seq_file *sf, void *v)
 	return 0;
 }
 
-static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
-				    struct cftype *cftype,
-				    u64 val)
+static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight)
 {
-	struct blkcg *blkcg = css_to_blkcg(css);
-	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
-	struct blkcg_gq *blkg;
-	int ret = -ERANGE;
-
-	if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
-		return ret;
-
-	ret = 0;
-	spin_lock_irq(&blkcg->lock);
-	bfqgd->weight = (unsigned short)val;
-	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
-		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
-
-		if (!bfqg)
-			continue;
 	/*
 	 * Setting the prio_changed flag of the entity
 	 * to 1 with new_weight == weight would re-set
 	 * the value of the weight to its ioprio mapping.
 	 * Set the flag only if necessary.
 	 */
-		if ((unsigned short)val != bfqg->entity.new_weight) {
-			bfqg->entity.new_weight = (unsigned short)val;
+	if ((unsigned short)weight != bfqg->entity.new_weight) {
+		bfqg->entity.new_weight = (unsigned short)weight;
 		/*
 		 * Make sure that the above new value has been
 		 * stored in bfqg->entity.new_weight before
@@ -965,6 +947,28 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
 		smp_wmb();
 		bfqg->entity.prio_changed = 1;
 	}
+}
+
+static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
+				    struct cftype *cftype,
+				    u64 val)
+{
+	struct blkcg *blkcg = css_to_blkcg(css);
+	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
+	struct blkcg_gq *blkg;
+	int ret = -ERANGE;
+
+	if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
+		return ret;
+
+	ret = 0;
+	spin_lock_irq(&blkcg->lock);
+	bfqgd->weight = (unsigned short)val;
+	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
+		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
+
+		if (bfqg)
+			bfq_group_set_weight(bfqg, val);
 	}
 	spin_unlock_irq(&blkcg->lock);