@@ -42,8 +42,10 @@ will display something like:

 	 Metadata file: /dev/loop4

 	 Data Space Used: 2.536 GB

 	 Data Space Total: 107.4 GB

+	 Data Space Available: 104.8 GB

 	 Metadata Space Used: 7.93 MB

 	 Metadata Space Total: 2.147 GB

+	 Metadata Space Available: 2.14 GB

 	 Udev Sync Supported: true

 	 Data loop file: /home/docker/devicemapper/devicemapper/data

 	 Metadata loop file: /home/docker/devicemapper/devicemapper/metadata

@@ -60,8 +62,10 @@ status information about the driver.

  *  `Metadata file` blockdevice file used for the devicemapper metadata

  *  `Data Space Used` tells how much of `Data file` is currently used

  *  `Data Space Total` tells max size the `Data file`

+ *  `Data Space Available` tells how much free space there is in the `Data file`. If you are using a loop device this will report the actual space available to the loop device on the underlying filesystem.

  *  `Metadata Space Used` tells how much of `Metadata file` is currently used

  *  `Metadata Space Total` tells max size the `Metadata file`

+ *  `Metadata Space Available` tells how much free space there is in the `Metadata file`. If you are using a loop device this will report the actual space available to the loop device on the underlying filesystem.

  *  `Udev Sync Supported` tells whether devicemapper is able to sync with Udev. Should be `true`.

  *  `Data loop file` file attached to `Data file`, if loopback device is used

  *  `Metadata loop file` file attached to `Metadata file`, if loopback device is used

@@ -100,8 +100,9 @@ type DeviceSet struct {

 }

 type DiskUsage struct {

-	Used  uint64

-	Total uint64

+	Used      uint64

+	Total     uint64

+	Available uint64

 }

 type Status struct {

@@ -1579,6 +1580,28 @@ func (devices *DeviceSet) MetadataDevicePath() string {

 	return devices.metadataDevice

 }

+func (devices *DeviceSet) getUnderlyingAvailableSpace(loopFile string) (uint64, error) {

+	buf := new(syscall.Statfs_t)

+	err := syscall.Statfs(loopFile, buf)

+	if err != nil {

+		log.Warnf("Warning: Couldn't stat loopfile filesystem %v: %v", loopFile, err)

+		return 0, err

+	}

+	return buf.Bfree * uint64(buf.Bsize), nil

+}

+

+func (devices *DeviceSet) isRealFile(loopFile string) (bool, error) {

+	if loopFile != "" {

+		fi, err := os.Stat(loopFile)

+		if err != nil {

+			log.Warnf("Warning: Couldn't stat loopfile %v: %v", loopFile, err)

+			return false, err

+		}

+		return fi.Mode().IsRegular(), nil

+	}

+	return false, nil

+}

+

 // Status returns the current status of this deviceset

 func (devices *DeviceSet) Status() *Status {

 	devices.Lock()

@@ -1600,12 +1623,28 @@ func (devices *DeviceSet) Status() *Status {

 		status.Data.Used = dataUsed * blockSizeInSectors * 512

 		status.Data.Total = dataTotal * blockSizeInSectors * 512

+		status.Data.Available = status.Data.Total - status.Data.Used

 		// metadata blocks are always 4k

 		status.Metadata.Used = metadataUsed * 4096

 		status.Metadata.Total = metadataTotal * 4096

+		status.Metadata.Available = status.Metadata.Total - status.Metadata.Used

 		status.SectorSize = blockSizeInSectors * 512

+

+		if check, _ := devices.isRealFile(devices.dataLoopFile); check {

+			actualSpace, err := devices.getUnderlyingAvailableSpace(devices.dataLoopFile)

+			if err == nil && actualSpace < status.Data.Available {

+				status.Data.Available = actualSpace

+			}

+		}

+

+		if check, _ := devices.isRealFile(devices.metadataLoopFile); check {

+			actualSpace, err := devices.getUnderlyingAvailableSpace(devices.metadataLoopFile)

+			if err == nil && actualSpace < status.Metadata.Available {

+				status.Metadata.Available = actualSpace

+			}

+		}

 	}

 	return status

@@ -72,8 +72,10 @@ func (d *Driver) Status() [][2]string {

 		{"Metadata file", s.MetadataFile},

 		{"Data Space Used", fmt.Sprintf("%s", units.HumanSize(float64(s.Data.Used)))},

 		{"Data Space Total", fmt.Sprintf("%s", units.HumanSize(float64(s.Data.Total)))},

+		{"Data Space Available", fmt.Sprintf("%s", units.HumanSize(float64(s.Data.Available)))},

 		{"Metadata Space Used", fmt.Sprintf("%s", units.HumanSize(float64(s.Metadata.Used)))},

 		{"Metadata Space Total", fmt.Sprintf("%s", units.HumanSize(float64(s.Metadata.Total)))},

+		{"Metadata Space Available", fmt.Sprintf("%s", units.HumanSize(float64(s.Metadata.Available)))},

 		{"Udev Sync Supported", fmt.Sprintf("%v", s.UdevSyncSupported)},

 	}

 	if len(s.DataLoopback) > 0 {