@@ -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.",

 	}