@@ -13,6 +13,9 @@ func init() {

 	DefaultDataLoopbackSize = 300 * 1024 * 1024

 	DefaultMetaDataLoopbackSize = 200 * 1024 * 1024

 	DefaultBaseFsSize = 300 * 1024 * 1024

+	if err := graphtest.InitLoopbacks(); err != nil {

+		panic(err)

+	}

 }

 // This avoids creating a new driver for each test if all tests are run

@@ -1,6 +1,7 @@

 package graphtest

 import (

+	"fmt"

 	"io/ioutil"

 	"os"

 	"path"

@@ -20,6 +21,46 @@ type Driver struct {

 	refCount int

 }

+// InitLoopbacks ensures that the loopback devices are properly created within

+// the system running the device mapper tests.

+func InitLoopbacks() error {

+	stat_t, err := getBaseLoopStats()

+	if err != nil {

+		return err

+	}

+	// create atleast 8 loopback files, ya, that is a good number

+	for i := 0; i < 8; i++ {

+		loopPath := fmt.Sprintf("/dev/loop%d", i)

+		// only create new loopback files if they don't exist

+		if _, err := os.Stat(loopPath); err != nil {

+			if mkerr := syscall.Mknod(loopPath,

+				uint32(stat_t.Mode|syscall.S_IFBLK), int((7<<8)|(i&0xff)|((i&0xfff00)<<12))); mkerr != nil {

+				return mkerr

+			}

+			os.Chown(loopPath, int(stat_t.Uid), int(stat_t.Gid))

+		}

+	}

+	return nil

+}

+

+// getBaseLoopStats inspects /dev/loop0 to collect uid,gid, and mode for the

+// loop0 device on the system.  If it does not exist we assume 0,0,0660 for the

+// stat data

+func getBaseLoopStats() (*syscall.Stat_t, error) {

+	loop0, err := os.Stat("/dev/loop0")

+	if err != nil {

+		if os.IsNotExist(err) {

+			return &syscall.Stat_t{

+				Uid:  0,

+				Gid:  0,

+				Mode: 0660,

+			}, nil

+		}

+		return nil, err

+	}

+	return loop0.Sys().(*syscall.Stat_t), nil

+}

+

 func newDriver(t *testing.T, name string) *Driver {

 	root, err := ioutil.TempDir("/var/tmp", "docker-graphtest-")

 	if err != nil {