Don't use separate bind mount for container

Since we're not not mounting anything but the base filesystem outside
the container we no longer need the separate bind mount at
/var/lib/docker/container/$id/root in order to see the base filesystem
without extra mounts. So, we drop this and mount (again) the container
root directly at the real basefs mountpoint.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
Upstream-commit: bf1b27dfcc6c4e049706d7d104e1abc5c330815d
Component: engine

components/engine/buildfile.go

@@ -374,7 +374,7 @@ func (b *buildFile) checkPathForAddition(orig string) error {
 func (b *buildFile) addContext(container *runtime.Container, orig, dest string, remote bool) error {
 	var (
 		origPath = path.Join(b.contextPath, orig)
-		destPath = path.Join(container.BasefsPath(), dest)
+		destPath = path.Join(container.RootfsPath(), dest)
 	)
 	// Preserve the trailing '/'
 	if strings.HasSuffix(dest, "/") {

components/engine/integration/utils_test.go

@@ -71,7 +71,7 @@ func containerFileExists(eng *engine.Engine, id, dir string, t utils.Fataler) bo
 		t.Fatal(err)
 	}
 	defer c.Unmount()
-	if _, err := os.Stat(path.Join(c.BasefsPath(), dir)); err != nil {
+	if _, err := os.Stat(path.Join(c.RootfsPath(), dir)); err != nil {
 		if os.IsNotExist(err) {
 			return false
 		}

components/engine/runtime/container.go

@@ -532,7 +532,7 @@ func (container *Container) Start() (err error) {
 	populateCommand(container)
 	container.command.Env = env
 
-	if err := mountVolumesForContainer(container, envPath); err != nil {
+	if err := setupMountsForContainer(container, envPath); err != nil {
 		return err
 	}
 
@@ -843,8 +843,6 @@ func (container *Container) cleanup() {
 		}
 	}
 
-	unmountVolumesForContainer(container)
-
 	if err := container.Unmount(); err != nil {
 		log.Printf("%v: Failed to umount filesystem: %v", container.ID, err)
 	}
@@ -1039,12 +1037,6 @@ func (container *Container) EnvConfigPath() (string, error) {
 // This method must be exported to be used from the lxc template
 // This directory is only usable when the container is running
 func (container *Container) RootfsPath() string {
-	return path.Join(container.root, "root")
-}
-
-// This is the stand-alone version of the root fs, without any additional mounts.
-// This directory is usable whenever the container is mounted (and not unmounted)
-func (container *Container) BasefsPath() string {
 	return container.basefs
 }
 

components/engine/runtime/runtime.go

@@ -174,7 +174,6 @@ func (runtime *Runtime) Register(container *Container) error {
 				runtime.execDriver.Kill(command, 9)
 			}
 			// ensure that the filesystem is also unmounted
-			unmountVolumesForContainer(container)
 			if err := container.Unmount(); err != nil {
 				utils.Debugf("ghost unmount error %s", err)
 			}
@@ -185,7 +184,6 @@ func (runtime *Runtime) Register(container *Container) error {
 			utils.Debugf("Container %s was supposed to be running but is not.", container.ID)
 			if runtime.config.AutoRestart {
 				utils.Debugf("Restarting")
-				unmountVolumesForContainer(container)
 				if err := container.Unmount(); err != nil {
 					utils.Debugf("restart unmount error %s", err)
 				}

components/engine/runtime/volumes.go

@@ -4,10 +4,8 @@ import (
 	"fmt"
 	"github.com/dotcloud/docker/archive"
 	"github.com/dotcloud/docker/execdriver"
-	"github.com/dotcloud/docker/pkg/mount"
 	"github.com/dotcloud/docker/utils"
 	"io/ioutil"
-	"log"
 	"os"
 	"path/filepath"
 	"strings"
@@ -35,29 +33,9 @@ func prepareVolumesForContainer(container *Container) error {
 	return nil
 }
 
-func mountVolumesForContainer(container *Container, envPath string) error {
-	// Setup the root fs as a bind mount of the base fs
-	var (
-		root    = container.RootfsPath()
-		runtime = container.runtime
-	)
-	if err := os.MkdirAll(root, 0755); err != nil && !os.IsExist(err) {
-		return nil
-	}
-
-	// Create a bind mount of the base fs as a place where we can add mounts
-	// without affecting the ability to access the base fs
-	if err := mount.Mount(container.basefs, root, "none", "bind,rw"); err != nil {
-		return err
-	}
-
-	// Make sure the root fs is private so the mounts here don't propagate to basefs
-	if err := mount.ForceMount(root, root, "none", "private"); err != nil {
-		return err
-	}
-
+func setupMountsForContainer(container *Container, envPath string) error {
 	mounts := []execdriver.Mount{
-		{runtime.sysInitPath, "/.dockerinit", false, true},
+		{container.runtime.sysInitPath, "/.dockerinit", false, true},
 		{envPath, "/.dockerenv", false, true},
 		{container.ResolvConfPath, "/etc/resolv.conf", false, true},
 	}
@@ -80,12 +58,6 @@ func mountVolumesForContainer(container *Container, envPath string) error {
 	return nil
 }
 
-func unmountVolumesForContainer(container *Container) {
-	if err := mount.Unmount(container.RootfsPath()); err != nil {
-		log.Printf("Failed to umount container: %v", err)
-	}
-}
-
 func applyVolumesFrom(container *Container) error {
 	if container.Config.VolumesFrom != "" {
 		for _, containerSpec := range strings.Split(container.Config.VolumesFrom, ",") {