util: add function to get the kernel version

Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/cephfs/volumemounter.go

@@ -29,7 +29,6 @@ import (
 
 	"github.com/ceph/ceph-csi/internal/util"
 
-	"golang.org/x/sys/unix"
 	"k8s.io/klog"
 )
 
@@ -151,12 +150,10 @@ func loadAvailableMounters(conf *util.Config) error {
 		klog.Errorf("failed to run mount.ceph %v", err)
 	} else {
 		// fetch the current running kernel info
-		utsname := unix.Utsname{}
-		err = unix.Uname(&utsname)
-		if err != nil {
-			return err
+		release, kvErr := util.KernelVersion()
+		if kvErr != nil {
+			return kvErr
 		}
-		release := string(utsname.Release[:64])
 
 		if conf.ForceKernelCephFS || kernelSupportsQuota(release) {
 			klog.V(1).Infof("loaded mounter: %s", volumeMounterKernel)

internal/util/util.go

@@ -25,6 +25,7 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 	"k8s.io/apimachinery/pkg/util/validation"
@@ -139,6 +140,17 @@ func ValidateDriverName(driverName string) error {
 	return err
 }
 
+// KernelVersion returns the version of the running Unix (like) system from the
+// 'utsname' structs 'release' component.
+func KernelVersion() (string, error) {
+	utsname := unix.Utsname{}
+	err := unix.Uname(&utsname)
+	if err != nil {
+		return "", err
+	}
+	return string(utsname.Release[:]), nil
+}
+
 // GenerateVolID generates a volume ID based on passed in parameters and version, to be returned
 // to the CO system
 func GenerateVolID(ctx context.Context, monitors string, cr *Credentials, locationID int64, pool, clusterID, objUUID string, volIDVersion uint16) (string, error) {

internal/util/util_test.go

@@ -142,3 +142,13 @@ func TestRoundOffVolSize(t *testing.T) {
 		})
 	}
 }
+
+func TestKernelVersion(t *testing.T) {
+	version, err := KernelVersion()
+	if err != nil {
+		t.Errorf("failed to get kernel version: %s", err)
+	}
+	if version == "" {
+		t.Error("version is empty, this is unexpected?!")
+	}
+}