Merge pull request #6291 from ningmingxiao/dev1

fix when kernel version < 4.13rc1 by using index=off cause test error

snapshots/overlay/overlay.go

@@ -107,13 +107,6 @@ func NewSnapshotter(root string, opts ...Opt) (snapshots.Snapshotter, error) {
 	if err := os.Mkdir(filepath.Join(root, "snapshots"), 0700); err != nil && !os.IsExist(err) {
 		return nil, err
 	}
-
-	// figure out whether "index=off" option is recognized by the kernel
-	var indexOff bool
-	if _, err = os.Stat("/sys/module/overlay/parameters/index"); err == nil {
-		indexOff = true
-	}
-
 	// figure out whether "userxattr" option is recognized by the kernel && needed
 	userxattr, err := overlayutils.NeedsUserXAttr(root)
 	if err != nil {
@@ -125,7 +118,7 @@ func NewSnapshotter(root string, opts ...Opt) (snapshots.Snapshotter, error) {
 		ms:            ms,
 		asyncRemove:   config.asyncRemove,
 		upperdirLabel: config.upperdirLabel,
-		indexOff:      indexOff,
+		indexOff:      supportsIndex(),
 		userxattr:     userxattr,
 	}, nil
 }
@@ -572,3 +565,11 @@ func (o *snapshotter) workPath(id string) string {
 func (o *snapshotter) Close() error {
 	return o.ms.Close()
 }
+
+// supportsIndex checks whether the "index=off" option is supported by the kernel.
+func supportsIndex() bool {
+	if _, err := os.Stat("/sys/module/overlay/parameters/index"); err == nil {
+		return true
+	}
+	return false
+}

snapshots/overlay/overlay_test.go

@@ -178,6 +178,9 @@ func testOverlayOverlayMount(t *testing.T, newSnapshotter testsuite.SnapshotterF
 	expected := []string{
 		"index=off",
 	}
+	if !supportsIndex() {
+		expected = expected[1:]
+	}
 	if userxattr, err := overlayutils.NeedsUserXAttr(root); err != nil {
 		t.Fatal(err)
 	} else if userxattr {
@@ -346,7 +349,11 @@ func testOverlayView(t *testing.T, newSnapshotter testsuite.SnapshotterFunc) {
 		t.Errorf("mount source should be overlay but received %q", m.Source)
 	}
 
+	supportsIndex := supportsIndex()
 	expectedOptions := 2
+	if !supportsIndex {
+		expectedOptions--
+	}
 	userxattr, err := overlayutils.NeedsUserXAttr(root)
 	if err != nil {
 		t.Fatal(err)
@@ -361,6 +368,9 @@ func testOverlayView(t *testing.T, newSnapshotter testsuite.SnapshotterFunc) {
 	lowers := getParents(ctx, o, root, "/tmp/view2")
 	expected = fmt.Sprintf("lowerdir=%s:%s", lowers[0], lowers[1])
 	optIdx := 1
+	if !supportsIndex {
+		optIdx--
+	}
 	if userxattr {
 		optIdx++
 	}