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.go

@@ -148,3 +148,20 @@ func CalculateTimeoutForVolume(minimumTimeout, timeoutIncrement int, pv *api.Per
 func RoundUpSize(volumeSizeBytes int64, allocationUnitBytes int64) int64 {
 	return (volumeSizeBytes + allocationUnitBytes - 1) / allocationUnitBytes
 }
+
+// GenerateVolumeName returns a PV name with clusterName prefix.
+// The function should be used to generate a name of GCE PD or Cinder volume.
+// It basically adds "<clusterName>-dynamic-" before the PV name,
+// making sure the resulting string fits given length and cuts "dynamic"
+// if not.
+func GenerateVolumeName(clusterName, pvName string, maxLength int) string {
+	prefix := clusterName + "-dynamic"
+	pvLen := len(pvName)
+
+	// cut the "<clusterName>-dynamic" to fit full pvName into maxLength
+	// +1 for the '-' dash
+	if pvLen+1+len(prefix) > maxLength {
+		prefix = prefix[:maxLength-pvLen-1]
+	}
+	return prefix + "-" + pvName
+}