fix partition resize

Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>

system/filesystem_linux.go

@@ -41,6 +41,17 @@ func ResizeRootFS() error {
 	partstart := "2048"
 	device := mountpoint[:len(mountpoint)-1]
 	partition := mountpoint[len(mountpoint)-1:]
+	mbr := make([]byte, 446)
+
+	f, err := os.OpenFile(device, os.O_RDONLY, os.FileMode(0400))
+	if err != nil {
+		return err
+	}
+	_, err = io.ReadFull(f, mbr)
+	f.Close()
+	if err != nil {
+		return err
+	}
 
 	cmd := exec.Command("fdisk", "-l", "-u", device)
 	stdout, err = cmd.StdoutPipe()
@@ -82,14 +93,17 @@ func ResizeRootFS() error {
 	stdin.Reset()
 
 	w, err := os.OpenFile(device, os.O_WRONLY, 0600)
-	if err == nil {
-		defer w.Close()
-		err = ioctl.BlkRRPart(w.Fd())
-		if err == nil {
-			return exec.Command("resize2fs", device+partition).Run()
+	if err != nil {
+		return err
 	}
+	_, err = w.Write(mbr)
+	if err != nil {
+		return err
 	}
 
+	err = ioctl.BlkRRPart(w.Fd())
+	w.Close()
+	if err != nil {
 		args := []string{}
 		for _, name := range []string{"partx", "partprobe", "kpartx"} {
 			if _, err = exec.LookPath(name); err == nil {
@@ -100,7 +114,10 @@ func ResizeRootFS() error {
 					args = []string{device}
 				}
 				log.Printf("update partition table via %s %s", name, strings.Join(args, " "))
-			exec.Command(name, args...).Run()
+				if err = exec.Command(name, args...).Run(); err == nil {
+					break
+				}
+			}
 		}
 	}
 	log.Printf("resize filesystem via %s %s", "resize2fs", device+partition)
@@ -108,10 +125,5 @@ func ResizeRootFS() error {
 	if err != nil {
 		return err
 	}
-	for _, name := range []string{"grub-install", "grub2-install"} {
-		if _, err = exec.LookPath(name); err == nil {
-			log.Printf("reinstall grub %s %s", name, device)
-			exec.Command(name, device).Run()
-		}
-	}
+	return nil
 }