@@ -6,7 +6,6 @@ import (

 	"github.com/dotcloud/docker/utils"

 	"io"

 	"io/ioutil"

-	"os/exec"

 	"path"

 	"path/filepath"

 	"strconv"

@@ -223,9 +222,9 @@ func (devices *DeviceSet) activateDeviceIfNeeded(hash string) error {

 func (devices *DeviceSet) createFilesystem(info *DevInfo) error {

 	devname := info.DevName()

-	err := exec.Command("mkfs.ext4", "-E", "discard,lazy_itable_init=0,lazy_journal_init=0", devname).Run()

+	err := execRun("mkfs.ext4", "-E", "discard,lazy_itable_init=0,lazy_journal_init=0", devname)

 	if err != nil {

-		err = exec.Command("mkfs.ext4", "-E", "discard,lazy_itable_init=0", devname).Run()

+		err = execRun("mkfs.ext4", "-E", "discard,lazy_itable_init=0", devname)

 	}

 	if err != nil {

 		utils.Debugf("\n--->Err: %s\n", err)

@@ -2,6 +2,7 @@ package devmapper

 import (

 	"os"

+	"os/exec"

 	"syscall"

 )

@@ -28,6 +29,10 @@ var (

 	osRemoveAll  = os.RemoveAll

 	osRename     = os.Rename

 	osReadlink   = os.Readlink

+

+	execRun = func(name string, args ...string) error {

+		return exec.Command(name, args...).Run()

+	}

 )

 const (