@@ -210,8 +210,13 @@ func (daemon *Daemon) setRWLayer(container *container.Container) error {

 		layerID = img.RootFS.ChainID()

 	}

-	rwLayer, err := daemon.layerStore.CreateRWLayer(container.ID, layerID, container.MountLabel, daemon.getLayerInit(), container.HostConfig.StorageOpt)

+	rwLayerOpts := &layer.CreateRWLayerOpts{

+		MountLabel: container.MountLabel,

+		InitFunc:   daemon.getLayerInit(),

+		StorageOpt: container.HostConfig.StorageOpt,

+	}

+	rwLayer, err := daemon.layerStore.CreateRWLayer(container.ID, layerID, rwLayerOpts)

 	if err != nil {

 		return err

 	}

@@ -126,7 +126,7 @@ func (ls *mockLayerStore) Get(chainID layer.ChainID) (layer.Layer, error) {

 func (ls *mockLayerStore) Release(l layer.Layer) ([]layer.Metadata, error) {

 	return []layer.Metadata{}, nil

 }

-func (ls *mockLayerStore) CreateRWLayer(string, layer.ChainID, string, layer.MountInit, map[string]string) (layer.RWLayer, error) {

+func (ls *mockLayerStore) CreateRWLayer(string, layer.ChainID, *layer.CreateRWLayerOpts) (layer.RWLayer, error) {

 	return nil, errors.New("not implemented")

 }

@@ -169,6 +169,13 @@ type Metadata struct {

 // RWLayer.

 type MountInit func(root string) error

+// CreateRWLayerOpts contains optional arguments to be passed to CreateRWLayer

+type CreateRWLayerOpts struct {

+	MountLabel string

+	InitFunc   MountInit

+	StorageOpt map[string]string

+}

+

 // Store represents a backend for managing both

 // read-only and read-write layers.

 type Store interface {

@@ -177,7 +184,7 @@ type Store interface {

 	Map() map[ChainID]Layer

 	Release(Layer) ([]Metadata, error)

-	CreateRWLayer(id string, parent ChainID, mountLabel string, initFunc MountInit, storageOpt map[string]string) (RWLayer, error)

+	CreateRWLayer(id string, parent ChainID, opts *CreateRWLayerOpts) (RWLayer, error)

 	GetRWLayer(id string) (RWLayer, error)

 	GetMountID(id string) (string, error)

 	ReleaseRWLayer(RWLayer) ([]Metadata, error)

@@ -444,7 +444,19 @@ func (ls *layerStore) Release(l Layer) ([]Metadata, error) {

 	return ls.releaseLayer(layer)

 }

-func (ls *layerStore) CreateRWLayer(name string, parent ChainID, mountLabel string, initFunc MountInit, storageOpt map[string]string) (RWLayer, error) {

+func (ls *layerStore) CreateRWLayer(name string, parent ChainID, opts *CreateRWLayerOpts) (RWLayer, error) {

+	var (

+		storageOpt map[string]string

+		initFunc   MountInit

+		mountLabel string

+	)

+

+	if opts != nil {

+		mountLabel = opts.MountLabel

+		storageOpt = opts.StorageOpt

+		initFunc = opts.InitFunc

+	}

+

 	ls.mountL.Lock()

 	defer ls.mountL.Unlock()

 	m, ok := ls.mounts[name]

@@ -84,7 +84,7 @@ type layerInit func(root string) error

 func createLayer(ls Store, parent ChainID, layerFunc layerInit) (Layer, error) {

 	containerID := stringid.GenerateRandomID()

-	mount, err := ls.CreateRWLayer(containerID, parent, "", nil, nil)

+	mount, err := ls.CreateRWLayer(containerID, parent, nil)

 	if err != nil {

 		return nil, err

 	}

@@ -276,7 +276,7 @@ func TestMountAndRegister(t *testing.T) {

 	size, _ := layer.Size()

 	t.Logf("Layer size: %d", size)

-	mount2, err := ls.CreateRWLayer("new-test-mount", layer.ChainID(), "", nil, nil)

+	mount2, err := ls.CreateRWLayer("new-test-mount", layer.ChainID(), nil)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -384,7 +384,7 @@ func TestStoreRestore(t *testing.T) {

 		t.Fatal(err)

 	}

-	m, err := ls.CreateRWLayer("some-mount_name", layer3.ChainID(), "", nil, nil)

+	m, err := ls.CreateRWLayer("some-mount_name", layer3.ChainID(), nil)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -415,7 +415,7 @@ func TestStoreRestore(t *testing.T) {

 	assertLayerEqual(t, layer3b, layer3)

 	// Create again with same name, should return error

-	if _, err := ls2.CreateRWLayer("some-mount_name", layer3b.ChainID(), "", nil, nil); err == nil {

+	if _, err := ls2.CreateRWLayer("some-mount_name", layer3b.ChainID(), nil); err == nil {

 		t.Fatal("Expected error creating mount with same name")

 	} else if err != ErrMountNameConflict {

 		t.Fatal(err)

@@ -380,7 +380,7 @@ func TestMountMigration(t *testing.T) {

 		Kind: archive.ChangeAdd,

 	})

-	if _, err := ls.CreateRWLayer("migration-mount", layer1.ChainID(), "", nil, nil); err == nil {

+	if _, err := ls.CreateRWLayer("migration-mount", layer1.ChainID(), nil); err == nil {

 		t.Fatal("Expected error creating mount with same name")

 	} else if err != ErrMountNameConflict {

 		t.Fatal(err)

@@ -32,7 +32,10 @@ func TestMountInit(t *testing.T) {

 		return initfile.ApplyFile(root)

 	}

-	m, err := ls.CreateRWLayer("fun-mount", layer.ChainID(), "", mountInit, nil)

+	rwLayerOpts := &CreateRWLayerOpts{

+		InitFunc: mountInit,

+	}

+	m, err := ls.CreateRWLayer("fun-mount", layer.ChainID(), rwLayerOpts)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -88,8 +91,11 @@ func TestMountSize(t *testing.T) {

 	mountInit := func(root string) error {

 		return newTestFile("file-init", contentInit, 0777).ApplyFile(root)

 	}

+	rwLayerOpts := &CreateRWLayerOpts{

+		InitFunc: mountInit,

+	}

-	m, err := ls.CreateRWLayer("mount-size", layer.ChainID(), "", mountInit, nil)

+	m, err := ls.CreateRWLayer("mount-size", layer.ChainID(), rwLayerOpts)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -137,8 +143,11 @@ func TestMountChanges(t *testing.T) {

 	mountInit := func(root string) error {

 		return initfile.ApplyFile(root)

 	}

+	rwLayerOpts := &CreateRWLayerOpts{

+		InitFunc: mountInit,

+	}

-	m, err := ls.CreateRWLayer("mount-changes", layer.ChainID(), "", mountInit, nil)

+	m, err := ls.CreateRWLayer("mount-changes", layer.ChainID(), rwLayerOpts)

 	if err != nil {

 		t.Fatal(err)

 	}