@@ -23,9 +23,10 @@ type Mount struct {

 	// Source specifies the name of the mount. Depending on mount type, this

 	// may be a volume name or a host path, or even ignored.

 	// Source is not supported for tmpfs (must be an empty value)

-	Source   string `json:",omitempty"`

-	Target   string `json:",omitempty"`

-	ReadOnly bool   `json:",omitempty"`

+	Source      string      `json:",omitempty"`

+	Target      string      `json:",omitempty"`

+	ReadOnly    bool        `json:",omitempty"`

+	Consistency Consistency `json:",omitempty"`

 	BindOptions   *BindOptions   `json:",omitempty"`

 	VolumeOptions *VolumeOptions `json:",omitempty"`

@@ -60,6 +61,20 @@ var Propagations = []Propagation{

 	PropagationSlave,

 }

+// Consistency represents the consistency requirements of a mount.

+type Consistency string

+

+const (

+	// ConsistencyFull guarantees bind-mount-like consistency

+	ConsistencyFull Consistency = "consistent"

+	// ConsistencyCached mounts can cache read data and FS structure

+	ConsistencyCached Consistency = "cached"

+	// ConsistencyDelegated mounts can cache read and written data and structure

+	ConsistencyDelegated Consistency = "delegated"

+	// ConsistencyDefault provides "consistent" behavior unless overridden

+	ConsistencyDefault Consistency = "default"

+)

+

 // BindOptions defines options specific to mounts of type "bind".

 type BindOptions struct {

 	Propagation Propagation `json:",omitempty"`

@@ -95,6 +95,8 @@ func (m *MountOpt) Set(value string) error {

 			if err != nil {

 				return fmt.Errorf("invalid value for %s: %s", key, value)

 			}

+		case "consistency":

+			mount.Consistency = mounttypes.Consistency(strings.ToLower(value))

 		case "bind-propagation":

 			bindOptions().Propagation = mounttypes.Propagation(strings.ToLower(value))

 		case "volume-nocopy":

@@ -30,6 +30,13 @@ var labelModes = map[string]bool{

 	"z": true,

 }

+// consistency modes

+var consistencyModes = map[mounttypes.Consistency]bool{

+	mounttypes.ConsistencyFull:      true,

+	mounttypes.ConsistencyCached:    true,

+	mounttypes.ConsistencyDelegated: true,

+}

+

 // BackwardsCompatible decides whether this mount point can be

 // used in old versions of Docker or not.

 // Only bind mounts and local volumes can be used in old versions of Docker.

@@ -62,6 +69,7 @@ func ValidMountMode(mode string) bool {

 	labelModeCount := 0

 	propagationModeCount := 0

 	copyModeCount := 0

+	consistencyModeCount := 0

 	for _, o := range strings.Split(mode, ",") {

 		switch {

@@ -73,13 +81,15 @@ func ValidMountMode(mode string) bool {

 			propagationModeCount++

 		case copyModeExists(o):

 			copyModeCount++

+		case consistencyModes[mounttypes.Consistency(o)]:

+			consistencyModeCount++

 		default:

 			return false

 		}

 	}

 	// Only one string for each mode is allowed.

-	if rwModeCount > 1 || labelModeCount > 1 || propagationModeCount > 1 || copyModeCount > 1 {

+	if rwModeCount > 1 || labelModeCount > 1 || propagationModeCount > 1 || copyModeCount > 1 || consistencyModeCount > 1 {

 		return false

 	}

 	return true