From e94095b0f35b6c53d8602420edc1943ae2f64eee Mon Sep 17 00:00:00 2001
From: Andrew Rynhard <andrew@andrewrynhard.com>
Date: Sat, 1 Dec 2018 15:41:39 -0800
Subject: [PATCH] refactor(init): remove unnecessary unmount/mount (#246)

---
 src/initramfs/cmd/init/main.go                      | 9 +--------
 src/initramfs/cmd/init/pkg/switchroot/switchroot.go | 7 ++-----
 2 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/src/initramfs/cmd/init/main.go b/src/initramfs/cmd/init/main.go
index c1bacd98c..f0db350aa 100644
--- a/src/initramfs/cmd/init/main.go
+++ b/src/initramfs/cmd/init/main.go
@@ -51,8 +51,7 @@ func initram() error {
 		return err
 	}
 	// Setup logging to /dev/kmsg.
-	var f *os.File
-	f, err := kmsg("[talos] [initramfs]")
+	_, err := kmsg("[talos] [initramfs]")
 	if err != nil {
 		return err
 	}
@@ -86,14 +85,8 @@ func initram() error {
 	if err := rootfs.Prepare(constants.NewRoot, data); err != nil {
 		return err
 	}
-	// Unmount the ROOT and DATA block devices.
-	log.Println("unmounting the ROOT and DATA partitions")
-	if err := mount.Unmount(); err != nil {
-		return err
-	}
 	// Perform the equivalent of switch_root.
 	log.Println("entering the new root")
-	f.Close() // nolint: errcheck
 	if err := switchroot.Switch(constants.NewRoot); err != nil {
 		return err
 	}
diff --git a/src/initramfs/cmd/init/pkg/switchroot/switchroot.go b/src/initramfs/cmd/init/pkg/switchroot/switchroot.go
index c3ab217f4..8c77b2831 100644
--- a/src/initramfs/cmd/init/pkg/switchroot/switchroot.go
+++ b/src/initramfs/cmd/init/pkg/switchroot/switchroot.go
@@ -82,13 +82,10 @@ func getDev(fd int) (dev uint64, err error) {
 	return stat.Dev, nil
 }
 
-// Switch performs a switch_root equivalent. See
+// Switch performs a switch_root. The caller must ensure that the ROOT and DATA
+// partitions are already mounted. See
 // https://github.com/karelzak/util-linux/blob/master/sys-utils/switch_root.c
 func Switch(s string) error {
-	// Mount the ROOT and DATA block devices at the new root.
-	if err := mount.Mount(s); err != nil {
-		return errors.Wrap(err, "error mounting block device")
-	}
 	// Move the special mount points to the new root.
 	if err := mount.Move(s); err != nil {
 		return errors.Wrap(err, "error moving special devices")