blk-cgroup: factor out blkcg_free_all_cpd()

To reduce some duplicated code, factor out blkcg_free_all_cpd(). No
functional change.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220629070917.3113016-3-yanaijie@huawei.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

@@ -1533,6 +1533,18 @@ void blkcg_deactivate_policy(struct request_queue *q,
 }
 EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
 
+static void blkcg_free_all_cpd(struct blkcg_policy *pol)
+{
+	struct blkcg *blkcg;
+
+	list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
+		if (blkcg->cpd[pol->plid]) {
+			pol->cpd_free_fn(blkcg->cpd[pol->plid]);
+			blkcg->cpd[pol->plid] = NULL;
+		}
+	}
+}
+
 /**
  * blkcg_policy_register - register a blkcg policy
  * @pol: blkcg policy to register
@@ -1597,14 +1609,9 @@ int blkcg_policy_register(struct blkcg_policy *pol)
 	return 0;
 
 err_free_cpds:
-	if (pol->cpd_free_fn) {
-		list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
-			if (blkcg->cpd[pol->plid]) {
-				pol->cpd_free_fn(blkcg->cpd[pol->plid]);
-				blkcg->cpd[pol->plid] = NULL;
-			}
-		}
-	}
+	if (pol->cpd_free_fn)
+		blkcg_free_all_cpd(pol);
+
 	blkcg_policy[pol->plid] = NULL;
 err_unlock:
 	mutex_unlock(&blkcg_pol_mutex);
@@ -1621,8 +1628,6 @@ EXPORT_SYMBOL_GPL(blkcg_policy_register);
  */
 void blkcg_policy_unregister(struct blkcg_policy *pol)
 {
-	struct blkcg *blkcg;
-
 	mutex_lock(&blkcg_pol_register_mutex);
 
 	if (WARN_ON(blkcg_policy[pol->plid] != pol))
@@ -1637,14 +1642,9 @@ void blkcg_policy_unregister(struct blkcg_policy *pol)
 	/* remove cpds and unregister */
 	mutex_lock(&blkcg_pol_mutex);
 
-	if (pol->cpd_free_fn) {
-		list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
-			if (blkcg->cpd[pol->plid]) {
-				pol->cpd_free_fn(blkcg->cpd[pol->plid]);
-				blkcg->cpd[pol->plid] = NULL;
-			}
-		}
-	}
+	if (pol->cpd_free_fn)
+		blkcg_free_all_cpd(pol);
+
 	blkcg_policy[pol->plid] = NULL;
 
 	mutex_unlock(&blkcg_pol_mutex);