devmapper: get rid of unused device id argument in unregisterDevice()

There is no need to populate device id during unregisterDevice(). Nobody
makes use of this information. We just need to remove file associated
with device and that file is looked up using the hash and not the
device id which is used for thin pool operations.

So get rid of device id argument to unregisterDevice().

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>

daemon/graphdriver/devmapper/deviceset.go

@@ -480,11 +480,10 @@ func (devices *DeviceSet) loadDeviceFilesOnStart() error {
 }
 
 // Should be called with devices.Lock() held.
-func (devices *DeviceSet) unregisterDevice(id int, hash string) error {
-	logrus.Debugf("devmapper: unregisterDevice(%v, %v)", id, hash)
+func (devices *DeviceSet) unregisterDevice(hash string) error {
+	logrus.Debugf("devmapper: unregisterDevice(%v)", hash)
 	info := &devInfo{
-		Hash:     hash,
-		DeviceID: id,
+		Hash: hash,
 	}
 
 	delete(devices.Devices, hash)
@@ -832,7 +831,7 @@ func (devices *DeviceSet) createRegisterDevice(hash string) (*devInfo, error) {
 	}
 
 	if err := devices.closeTransaction(); err != nil {
-		devices.unregisterDevice(deviceID, hash)
+		devices.unregisterDevice(hash)
 		devicemapper.DeleteDevice(devices.getPoolDevName(), deviceID)
 		devices.markDeviceIDFree(deviceID)
 		return nil, err
@@ -932,7 +931,7 @@ func (devices *DeviceSet) createRegisterSnapDevice(hash string, baseInfo *devInf
 	}
 
 	if err := devices.closeTransaction(); err != nil {
-		devices.unregisterDevice(deviceID, hash)
+		devices.unregisterDevice(hash)
 		devicemapper.DeleteDevice(devices.getPoolDevName(), deviceID)
 		devices.markDeviceIDFree(deviceID)
 		return err
@@ -2010,7 +2009,7 @@ func (devices *DeviceSet) deleteTransaction(info *devInfo, syncDelete bool) erro
 	}
 
 	if err == nil {
-		if err := devices.unregisterDevice(info.DeviceID, info.Hash); err != nil {
+		if err := devices.unregisterDevice(info.Hash); err != nil {
 			return err
 		}
 		// If device was already in deferred delete state that means