uploader flush buffer for restore

Signed-off-by: Lyndon-Li <lyonghui@vmware.com>

pkg/uploader/kopia/flush_volume_linux.go

@@ -0,0 +1,47 @@
+//go:build linux
+// +build linux
+
+/*
+Copyright The Velero Contributors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kopia
+
+import (
+	"os"
+
+	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
+)
+
+func flushVolume(dirPath string) error {
+	dir, err := os.Open(dirPath)
+	if err != nil {
+		return errors.Wrapf(err, "error opening dir %v", dirPath)
+	}
+
+	raw, err := dir.SyscallConn()
+	if err != nil {
+		return errors.Wrapf(err, "error getting handle of dir %v", dirPath)
+	}
+
+	raw.Control(func(fd uintptr) {
+		if e := unix.Syncfs(int(fd)); e != nil {
+			err = e
+		}
+	})
+
+	return errors.Wrapf(err, "error syncing dir %v", dirPath)
+}