Add SELinux feature check for iSCSI volume plugin

In theory the check is not necessary, but for sake of robustness and
completenes, let's check SELinuxMountReadWriteOncePod feature gate before
assuming anything about SELinux labels.

pkg/volume/iscsi/iscsi.go

@@ -24,7 +24,9 @@ import (
 	"strconv"
 	"strings"
 
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/klog/v2"
+	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/mount-utils"
 	utilexec "k8s.io/utils/exec"
 	"k8s.io/utils/io"
@@ -366,9 +368,12 @@ func (b *iscsiDiskMounter) SetUpAt(dir string, mounterArgs volume.MounterArgs) e
 	if err != nil {
 		klog.Errorf("iscsi: failed to setup")
 	}
-	// The volume must have been mounted in MountDevice with -o context.
-	// TODO: extract from mount table in GetAttributes() to be sure?
-	b.mountedWithSELinuxContext = mounterArgs.SELinuxLabel != ""
+
+	if utilfeature.DefaultFeatureGate.Enabled(features.SELinuxMountReadWriteOncePod) {
+		// The volume must have been mounted in MountDevice with -o context.
+		// TODO: extract from mount table in GetAttributes() to be sure?
+		b.mountedWithSELinuxContext = mounterArgs.SELinuxLabel != ""
+	}
 	return err
 }