new_code.go

	oldSize := oldPvc.Spec.Resources.Requests[api.ResourceStorage]
	newSize := pvc.Spec.Resources.Requests[api.ResourceStorage]

	if newSize.Cmp(oldSize) <= 0 {
		return nil
	}

	if oldPvc.Status.Phase != api.ClaimBound {
		return admission.NewForbidden(a, fmt.Errorf("Only bound persistent volume claims can be expanded"))
	}

	// Growing Persistent volumes is only allowed for PVCs for which their StorageClass
	// explicitly allows it
	if !pvcr.allowResize(pvc, oldPvc) {
		return admission.NewForbidden(a, fmt.Errorf("only dynamically provisioned pvc can be resized and "+
			"the storageclass that provisions the pvc must support resize"))
	}

	// volume plugin must support resize
	pv, err := pvcr.pvLister.Get(pvc.Spec.VolumeName)
	if err != nil {
		return admission.NewForbidden(a, fmt.Errorf("Error updating persistent volume claim because fetching associated persistent volume failed"))
	}

	if !pvcr.checkVolumePlugin(pv) {
		return admission.NewForbidden(a, fmt.Errorf("volume plugin does not support resize"))
	}
	return nil

old_code.go

	oldSize := oldPvc.Spec.Resources.Requests[api.ResourceStorage]
	newSize := pvc.Spec.Resources.Requests[api.ResourceStorage]

	if newSize.Cmp(oldSize) > 0 {
		if oldPvc.Status.Phase != api.ClaimBound {
			return admission.NewForbidden(a, fmt.Errorf("Only bound persistent volume claims can be expanded"))
		}

		// Growing Persistent volumes is only allowed for PVCs for which their StorageClass
		// explicitly allows it
		if !pvcr.allowResize(pvc, oldPvc) {
			return admission.NewForbidden(a, fmt.Errorf("only dynamically provisioned pvc can be resized and "+
				"the storageclass that provisions the pvc must support resize"))
		}

		// volume plugin must support resize
		pv, err := pvcr.pvLister.Get(pvc.Spec.VolumeName)
		if err != nil {
			return admission.NewForbidden(a, fmt.Errorf("Error updating persistent volume claim because fetching associated persistent volume failed"))
		}

		if !pvcr.checkVolumePlugin(pv) {
			return admission.NewForbidden(a, fmt.Errorf("volume plugin does not support resize"))
		}

	}

	return nil