IsReadOnly bool on builder

pkg/volume/rbd/rbd.go

@@ -216,6 +216,10 @@ type rbdCleaner struct {
 
 var _ volume.Cleaner = &rbdCleaner{}
 
+func (b *rbd) IsReadOnly() bool {
+	return b.ReadOnly
+}
+
 // Unmounts the bind mount, and detaches the disk only if the disk
 // resource was the last reference to that disk on the kubelet.
 func (c *rbdCleaner) TearDown() error {