@@ -15,11 +15,11 @@ import (

 	"path/filepath"

 	"strconv"

 	"strings"

+	"sync"

 	"syscall"

 	"time"

 	"unsafe"

-	"github.com/Microsoft/go-winio"

 	"github.com/Microsoft/go-winio/archive/tar"

 	"github.com/Microsoft/go-winio/backuptar"

 	"github.com/Microsoft/hcsshim"

@@ -31,6 +31,7 @@ import (

 	"github.com/docker/docker/pkg/longpath"

 	"github.com/docker/docker/pkg/reexec"

 	"github.com/docker/docker/pkg/system"

+	"github.com/docker/docker/vendor/src/github.com/Microsoft/go-winio"

 	"github.com/vbatts/tar-split/tar/storage"

 )

@@ -43,10 +44,22 @@ func init() {

 	reexec.Register("docker-windows-write-layer", writeLayer)

 }

+type checker struct {

+}

+

+func (c *checker) IsMounted(path string) bool {

+	return false

+}

+

 // Driver represents a windows graph driver.

 type Driver struct {

 	// info stores the shim driver information

 	info hcsshim.DriverInfo

+	ctr  *graphdriver.RefCounter

+	// it is safe for windows to use a cache here because it does not support

+	// restoring containers when the daemon dies.

+	cacheMu sync.Mutex

+	cache   map[string]string

 }

 func isTP5OrOlder() bool {

@@ -61,6 +74,8 @@ func InitFilter(home string, options []string, uidMaps, gidMaps []idtools.IDMap)

 			HomeDir: home,

 			Flavour: filterDriver,

 		},

+		cache: make(map[string]string),

+		ctr:   graphdriver.NewRefCounter(&checker{}),

 	}

 	return d, nil

 }

@@ -211,17 +226,23 @@ func (d *Driver) Get(id, mountLabel string) (string, error) {

 	if err != nil {

 		return "", err

 	}

+	if count := d.ctr.Increment(rID); count > 1 {

+		return d.cache[rID], nil

+	}

 	// Getting the layer paths must be done outside of the lock.

 	layerChain, err := d.getLayerChain(rID)

 	if err != nil {

+		d.ctr.Decrement(rID)

 		return "", err

 	}

 	if err := hcsshim.ActivateLayer(d.info, rID); err != nil {

+		d.ctr.Decrement(rID)

 		return "", err

 	}

 	if err := hcsshim.PrepareLayer(d.info, rID, layerChain); err != nil {

+		d.ctr.Decrement(rID)

 		if err2 := hcsshim.DeactivateLayer(d.info, rID); err2 != nil {

 			logrus.Warnf("Failed to Deactivate %s: %s", id, err)

 		}

@@ -230,11 +251,15 @@ func (d *Driver) Get(id, mountLabel string) (string, error) {

 	mountPath, err := hcsshim.GetLayerMountPath(d.info, rID)

 	if err != nil {

+		d.ctr.Decrement(rID)

 		if err2 := hcsshim.DeactivateLayer(d.info, rID); err2 != nil {

 			logrus.Warnf("Failed to Deactivate %s: %s", id, err)

 		}

 		return "", err

 	}

+	d.cacheMu.Lock()

+	d.cache[rID] = mountPath

+	d.cacheMu.Unlock()

 	// If the layer has a mount path, use that. Otherwise, use the

 	// folder path.

@@ -255,6 +280,12 @@ func (d *Driver) Put(id string) error {

 	if err != nil {

 		return err

 	}

+	if count := d.ctr.Decrement(rID); count > 0 {

+		return nil

+	}

+	d.cacheMu.Lock()

+	delete(d.cache, rID)

+	d.cacheMu.Unlock()

 	if err := hcsshim.UnprepareLayer(d.info, rID); err != nil {

 		return err