Merge pull request #2518 from XiaodongLoong/redundant_chroot_param

remove redundant parameter of chroot function

libcontainer/rootfs_linux.go

@@ -110,7 +110,7 @@ func prepareRootfs(pipe io.ReadWriter, iConfig *initConfig) (err error) {
 	} else if config.Namespaces.Contains(configs.NEWNS) {
 		err = pivotRoot(config.Rootfs)
 	} else {
-		err = chroot(config.Rootfs)
+		err = chroot()
 	}
 	if err != nil {
 		return newSystemErrorWithCause(err, "jailing process inside rootfs")
@@ -836,10 +836,10 @@ func msMoveRoot(rootfs string) error {
 	if err := unix.Mount(rootfs, "/", "", unix.MS_MOVE, ""); err != nil {
 		return err
 	}
-	return chroot(rootfs)
+	return chroot()
 }
 
-func chroot(rootfs string) error {
+func chroot() error {
 	if err := unix.Chroot("."); err != nil {
 		return err
 	}