@@ -123,10 +123,14 @@ func (daemon *Daemon) cleanupContainer(container *container.Container, forceRemo

 		return fmt.Errorf("Unable to remove filesystem for %v: %v", container.ID, err)

 	}

-	metadata, err := daemon.layerStore.ReleaseRWLayer(container.RWLayer)

-	layer.LogReleaseMetadata(metadata)

-	if err != nil && err != layer.ErrMountDoesNotExist {

-		return fmt.Errorf("Driver %s failed to remove root filesystem %s: %s", daemon.GraphDriverName(), container.ID, err)

+	// When container creation fails and `RWLayer` has not been created yet, we

+	// do not call `ReleaseRWLayer`

+	if container.RWLayer != nil {

+		metadata, err := daemon.layerStore.ReleaseRWLayer(container.RWLayer)

+		layer.LogReleaseMetadata(metadata)

+		if err != nil && err != layer.ErrMountDoesNotExist {

+			return fmt.Errorf("Driver %s failed to remove root filesystem %s: %s", daemon.GraphDriverName(), container.ID, err)

+		}

 	}

 	return nil

@@ -68,15 +68,15 @@ func (s *DockerSuite) TestCreateGrowRootfs(c *check.C) {

 	cleanedContainerID := strings.TrimSpace(out)

 	inspectOut := inspectField(c, cleanedContainerID, "HostConfig.StorageOpt")

-	c.Assert(inspectOut, checker.Equals, "[size=120G]")

+	c.Assert(inspectOut, checker.Equals, "map[size:120G]")

 }

 // Make sure we cannot shrink the container's rootfs at creation time.

 func (s *DockerSuite) TestCreateShrinkRootfs(c *check.C) {

 	testRequires(c, Devicemapper)

-	// Ensure this fails

-	out, _, err := dockerCmdWithError("create", "--storage-opt", "size=80G", "busybox")

+	// Ensure this fails because of the defaultBaseFsSize is 10G

+	out, _, err := dockerCmdWithError("create", "--storage-opt", "size=5G", "busybox")

 	c.Assert(err, check.NotNil, check.Commentf(out))

 	c.Assert(out, checker.Contains, "Container size cannot be smaller than")

 }

@@ -54,6 +54,11 @@ var (

 	dockerBasePath       string

 	volumesConfigPath    string

 	containerStoragePath string

+

+	// daemonStorageDriver is held globally so that tests can know the storage

+	// driver of the daemon. This is initialized in docker_utils by sending

+	// a version call to the daemon and examining the response header.

+	daemonStorageDriver string

 )

 const (

@@ -67,6 +67,7 @@ func init() {

 		panic(fmt.Errorf("Init failed to unmarshal docker info: %v", err))

 	}

+	daemonStorageDriver = info.Driver

 	dockerBasePath = info.DockerRootDir

 	volumesConfigPath = filepath.Join(dockerBasePath, "volumes")

 	containerStoragePath = filepath.Join(dockerBasePath, "containers")

@@ -109,22 +109,14 @@ var (

 	}

 	NotOverlay = testRequirement{

 		func() bool {

-			cmd := exec.Command("grep", "^overlay / overlay", "/proc/mounts")

-			if err := cmd.Run(); err != nil {

-				return true

-			}

-			return false

+			return !strings.HasPrefix(daemonStorageDriver, "overlay")

 		},

 		"Test requires underlying root filesystem not be backed by overlay.",

 	}

 	Devicemapper = testRequirement{

 		func() bool {

-			cmd := exec.Command("grep", "^devicemapper / devicemapper", "/proc/mounts")

-			if err := cmd.Run(); err != nil {

-				return false

-			}

-			return true

+			return strings.HasPrefix(daemonStorageDriver, "devicemapper")

 		},

 		"Test requires underlying root filesystem to be backed by devicemapper.",

 	}