diff --git a/[refs] b/[refs]
index 50c204b1a1f6..ac41a067eb04 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3ad19b8fb07497f975aa6aba187198ce11191dd2
+refs/heads/master: bd86055fc938493259a15dc00ee77435b4d2e83f
diff --git a/trunk/drivers/s390/block/scm_blk_cluster.c b/trunk/drivers/s390/block/scm_blk_cluster.c
index f4bb61b0cea1..c0d102e3a48b 100644
--- a/trunk/drivers/s390/block/scm_blk_cluster.c
+++ b/trunk/drivers/s390/block/scm_blk_cluster.c
@@ -223,6 +223,8 @@ void scm_cluster_request_irq(struct scm_request *scmrq)
 
 bool scm_cluster_size_valid(void)
 {
-	return write_cluster_size == 0 || write_cluster_size == 32 ||
-		write_cluster_size == 64 || write_cluster_size == 128;
+	if (write_cluster_size == 1 || write_cluster_size > 128)
+		return false;
+
+	return !(write_cluster_size & (write_cluster_size - 1));
 }