@@ -189,7 +189,9 @@ func (ls *layerStore) loadLayer(layer ChainID) (*roLayer, error) {

 }

 func (ls *layerStore) loadMount(mount string) error {

-	if _, ok := ls.mounts[mount]; ok {

+	ls.mountL.Lock()

+	defer ls.mountL.Unlock()

+	if m := ls.mounts[mount]; m != nil {

 		return nil

 	}

@@ -477,7 +479,7 @@ func (ls *layerStore) Release(l Layer) ([]Metadata, error) {

 	return ls.releaseLayer(layer)

 }

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

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

 	var (

 		storageOpt map[string]string

 		initFunc   MountInit

@@ -491,13 +493,21 @@ func (ls *layerStore) CreateRWLayer(name string, parent ChainID, opts *CreateRWL

 	}

 	ls.mountL.Lock()

-	defer ls.mountL.Unlock()

-	m, ok := ls.mounts[name]

-	if ok {

+	if _, ok := ls.mounts[name]; ok {

+		ls.mountL.Unlock()

 		return nil, ErrMountNameConflict

 	}

+	// Avoid name collision by temporary assigning nil

+	ls.mounts[name] = nil

+	ls.mountL.Unlock()

+	defer func() {

+		if err != nil {

+			ls.mountL.Lock()

+			delete(ls.mounts, name)

+			ls.mountL.Unlock()

+		}

+	}()

-	var err error

 	var pid string

 	var p *roLayer

 	if string(parent) != "" {

@@ -517,7 +527,7 @@ func (ls *layerStore) CreateRWLayer(name string, parent ChainID, opts *CreateRWL

 		}()

 	}

-	m = &mountedLayer{

+	m := &mountedLayer{

 		name:       name,

 		parent:     p,

 		mountID:    ls.mountID(name),

@@ -528,7 +538,7 @@ func (ls *layerStore) CreateRWLayer(name string, parent ChainID, opts *CreateRWL

 	if initFunc != nil {

 		pid, err = ls.initMount(m.mountID, pid, mountLabel, initFunc, storageOpt)

 		if err != nil {

-			return nil, err

+			return

 		}

 		m.initID = pid

 	}

@@ -538,10 +548,10 @@ func (ls *layerStore) CreateRWLayer(name string, parent ChainID, opts *CreateRWL

 	}

 	if err = ls.driver.CreateReadWrite(m.mountID, pid, createOpts); err != nil {

-		return nil, err

+		return

 	}

 	if err = ls.saveMount(m); err != nil {

-		return nil, err

+		return

 	}

 	return m.getReference(), nil

@@ -549,9 +559,9 @@ func (ls *layerStore) CreateRWLayer(name string, parent ChainID, opts *CreateRWL

 func (ls *layerStore) GetRWLayer(id string) (RWLayer, error) {

 	ls.mountL.Lock()

-	defer ls.mountL.Unlock()

-	mount, ok := ls.mounts[id]

-	if !ok {

+	mount := ls.mounts[id]

+	ls.mountL.Unlock()

+	if mount == nil {

 		return nil, ErrMountDoesNotExist

 	}

@@ -561,8 +571,8 @@ func (ls *layerStore) GetRWLayer(id string) (RWLayer, error) {

 func (ls *layerStore) GetMountID(id string) (string, error) {

 	ls.mountL.Lock()

 	defer ls.mountL.Unlock()

-	mount, ok := ls.mounts[id]

-	if !ok {

+	mount := ls.mounts[id]

+	if mount == nil {

 		return "", ErrMountDoesNotExist

 	}

 	logrus.Debugf("GetMountID id: %s -> mountID: %s", id, mount.mountID)

@@ -572,9 +582,9 @@ func (ls *layerStore) GetMountID(id string) (string, error) {

 func (ls *layerStore) ReleaseRWLayer(l RWLayer) ([]Metadata, error) {

 	ls.mountL.Lock()

-	defer ls.mountL.Unlock()

-	m, ok := ls.mounts[l.Name()]

-	if !ok {

+	m := ls.mounts[l.Name()]

+	ls.mountL.Unlock()

+	if m == nil {

 		return []Metadata{}, nil

 	}

@@ -606,7 +616,9 @@ func (ls *layerStore) ReleaseRWLayer(l RWLayer) ([]Metadata, error) {

 		return nil, err

 	}

+	ls.mountL.Lock()

 	delete(ls.mounts, m.Name())

+	ls.mountL.Unlock()

 	ls.layerL.Lock()

 	defer ls.layerL.Unlock()

@@ -634,7 +646,9 @@ func (ls *layerStore) saveMount(mount *mountedLayer) error {

 		}

 	}

+	ls.mountL.Lock()

 	ls.mounts[mount.name] = mount

+	ls.mountL.Unlock()

 	return nil

 }

@@ -18,9 +18,9 @@ import (

 // after migration the layer may be retrieved by the given name.

 func (ls *layerStore) CreateRWLayerByGraphID(name, graphID string, parent ChainID) (err error) {

 	ls.mountL.Lock()

-	defer ls.mountL.Unlock()

-	m, ok := ls.mounts[name]

-	if ok {

+	m := ls.mounts[name]

+	ls.mountL.Unlock()

+	if m != nil {

 		if m.parent.chainID != parent {

 			return errors.New("name conflict, mismatched parent")

 		}