Add PV.Name into names of generated GCE/AWS/OSP volumes.

Volume names have now format <cluster-name>-dynamic-<pv-name>.

pv-name is guaranteed to be unique in Kubernetes cluster, adding
<cluster-name> ensures we don't conflict with any running cluster
in the cloud project (kube-controller-manager --cluster-name=XXX).

'kubernetes' is the default cluster name.

pkg/volume/util_test.go

@@ -128,3 +128,28 @@ func TestCalculateTimeoutForVolume(t *testing.T) {
 		t.Errorf("Expected 4500 for timeout but got %v", timeout)
 	}
 }
+
+func TestGenerateVolumeName(t *testing.T) {
+
+	// Normal operation, no truncate
+	v1 := GenerateVolumeName("kubernetes", "pv-cinder-abcde", 255)
+	if v1 != "kubernetes-dynamic-pv-cinder-abcde" {
+		t.Errorf("Expected kubernetes-dynamic-pv-cinder-abcde, got %s", v1)
+	}
+
+	// Truncate trailing "6789-dynamic"
+	prefix := strings.Repeat("0123456789", 9) // 90 characters prefix + 8 chars. of "-dynamic"
+	v2 := GenerateVolumeName(prefix, "pv-cinder-abcde", 100)
+	expect := prefix[:84] + "-pv-cinder-abcde"
+	if v2 != expect {
+		t.Errorf("Expected %s, got %s", expect, v2)
+	}
+
+	// Truncate really long cluster name
+	prefix = strings.Repeat("0123456789", 1000) // 10000 characters prefix
+	v3 := GenerateVolumeName(prefix, "pv-cinder-abcde", 100)
+	if v3 != expect {
+		t.Errorf("Expected %s, got %s", expect, v3)
+	}
+
+}