@@ -35,7 +35,7 @@ import (

 var (

 	defaultDataLoopbackSize     int64  = 100 * 1024 * 1024 * 1024

 	defaultMetaDataLoopbackSize int64  = 2 * 1024 * 1024 * 1024

-	defaultBaseFsSize           uint64 = 100 * 1024 * 1024 * 1024

+	defaultBaseFsSize           uint64 = 10 * 1024 * 1024 * 1024

 	defaultThinpBlockSize       uint32 = 128 // 64K = 128 512b sectors

 	defaultUdevSyncOverride            = false

 	maxDeviceID                        = 0xffffff // 24 bit, pool limit

@@ -47,6 +47,7 @@ var (

 	driverDeferredRemovalSupport = false

 	enableDeferredRemoval        = false

 	enableDeferredDeletion       = false

+	userBaseSize                 = false

 )

 const deviceSetMetaFile string = "deviceset-metadata"

@@ -1056,6 +1057,80 @@ func (devices *DeviceSet) setupVerifyBaseImageUUIDFS(baseInfo *devInfo) error {

 	return nil

 }

+func (devices *DeviceSet) checkGrowBaseDeviceFS(info *devInfo) error {

+

+	if !userBaseSize {

+		return nil

+	}

+

+	if devices.baseFsSize < devices.getBaseDeviceSize() {

+		return fmt.Errorf("devmapper: Base device size cannot be smaller than %s", units.HumanSize(float64(devices.getBaseDeviceSize())))

+	}

+

+	if devices.baseFsSize == devices.getBaseDeviceSize() {

+		return nil

+	}

+

+	info.lock.Lock()

+	defer info.lock.Unlock()

+

+	devices.Lock()

+	defer devices.Unlock()

+

+	info.Size = devices.baseFsSize

+

+	if err := devices.saveMetadata(info); err != nil {

+		// Try to remove unused device

+		delete(devices.Devices, info.Hash)

+		return err

+	}

+

+	return devices.growFS(info)

+}

+

+func (devices *DeviceSet) growFS(info *devInfo) error {

+	if err := devices.activateDeviceIfNeeded(info, false); err != nil {

+		return fmt.Errorf("Error activating devmapper device: %s", err)

+	}

+

+	defer devices.deactivateDevice(info)

+

+	fsMountPoint := "/run/docker/mnt"

+	if _, err := os.Stat(fsMountPoint); os.IsNotExist(err) {

+		if err := os.MkdirAll(fsMountPoint, 0700); err != nil {

+			return err

+		}

+		defer os.RemoveAll(fsMountPoint)

+	}

+

+	options := ""

+	if devices.BaseDeviceFilesystem == "xfs" {

+		// XFS needs nouuid or it can't mount filesystems with the same fs

+		options = joinMountOptions(options, "nouuid")

+	}

+	options = joinMountOptions(options, devices.mountOptions)

+

+	if err := mount.Mount(info.DevName(), fsMountPoint, devices.BaseDeviceFilesystem, options); err != nil {

+		return fmt.Errorf("Error mounting '%s' on '%s': %s", info.DevName(), fsMountPoint, err)

+	}

+

+	defer syscall.Unmount(fsMountPoint, syscall.MNT_DETACH)

+

+	switch devices.BaseDeviceFilesystem {

+	case "ext4":

+		if out, err := exec.Command("resize2fs", info.DevName()).CombinedOutput(); err != nil {

+			return fmt.Errorf("Failed to grow rootfs:%v:%s", err, string(out))

+		}

+	case "xfs":

+		if out, err := exec.Command("xfs_growfs", info.DevName()).CombinedOutput(); err != nil {

+			return fmt.Errorf("Failed to grow rootfs:%v:%s", err, string(out))

+		}

+	default:

+		return fmt.Errorf("Unsupported filesystem type %s", devices.BaseDeviceFilesystem)

+	}

+	return nil

+}

+

 func (devices *DeviceSet) setupBaseImage() error {

 	oldInfo, _ := devices.lookupDeviceWithLock("")

@@ -1069,9 +1144,8 @@ func (devices *DeviceSet) setupBaseImage() error {

 				return err

 			}

-			if devices.baseFsSize != defaultBaseFsSize && devices.baseFsSize != devices.getBaseDeviceSize() {

-				logrus.Warnf("devmapper: Base device is already initialized to size %s, new value of base device size %s will not take effect",

-					units.HumanSize(float64(devices.getBaseDeviceSize())), units.HumanSize(float64(devices.baseFsSize)))

+			if err := devices.checkGrowBaseDeviceFS(oldInfo); err != nil {

+				return err

 			}

 			return nil

@@ -2379,6 +2453,7 @@ func NewDeviceSet(root string, doInit bool, options []string, uidMaps, gidMaps [

 			if err != nil {

 				return nil, err

 			}

+			userBaseSize = true

 			devices.baseFsSize = uint64(size)

 		case "dm.loopdatasize":

 			size, err := units.RAMInBytes(val)

@@ -213,11 +213,23 @@ options for `zfs` start with `zfs`.

 *  `dm.basesize`

     Specifies the size to use when creating the base device, which limits the

-    size of images and containers. The default value is 100G. Note, thin devices

-    are inherently "sparse", so a 100G device which is mostly empty doesn't use

-    100 GB of space on the pool. However, the filesystem will use more space for

+    size of images and containers. The default value is 10G. Note, thin devices

+    are inherently "sparse", so a 10G device which is mostly empty doesn't use

+    10 GB of space on the pool. However, the filesystem will use more space for

     the empty case the larger the device is.

+    The base device size can be increased at daemon restart which will allow

+    all future images and containers (based on those new images) to be of the 

+    new base device size.

+

+    Example use: 

+

+        $ docker daemon --storage-opt dm.basesize=50G

+

+    This will increase the base device size to 50G. The Docker daemon will throw an 

+    error if existing base device size is larger than 50G. A user can use 

+    this option to expand the base device size however shrinking is not permitted.

+

     This value affects the system-wide "base" empty filesystem

     that may already be initialized and inherited by pulled images. Typically,

     a change to this value requires additional steps to take effect:

@@ -249,11 +249,11 @@ You can use the `lsblk` command to see the device files created above and the `p

     NAME                       MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT

     xvda                       202:0    0    8G  0 disk

     └─xvda1                    202:1    0    8G  0 part /

-    xvdf                       202:80   0  100G  0 disk

+    xvdf                       202:80   0   10G  0 disk

     ├─vg--docker-data          253:0    0   90G  0 lvm

-    │ └─docker-202:1-1032-pool 253:2    0  100G  0 dm

+    │ └─docker-202:1-1032-pool 253:2    0   10G  0 dm

     └─vg--docker-metadata      253:1    0    4G  0 lvm

-      └─docker-202:1-1032-pool 253:2    0  100G  0 dm

+      └─docker-202:1-1032-pool 253:2    0   10G  0 dm

 The diagram below shows the image from prior examples updated with the detail from the `lsblk` command above.

@@ -271,12 +271,22 @@ Example use: `docker daemon --storage-opt dm.thinpooldev=/dev/mapper/thin-pool`

 #### dm.basesize

 Specifies the size to use when creating the base device, which limits

-the size of images and containers. The default value is 100G. Note,

-thin devices are inherently "sparse", so a 100G device which is mostly

-empty doesn't use 100 GB of space on the pool. However, the filesystem

+the size of images and containers. The default value is 10G. Note,

+thin devices are inherently "sparse", so a 10G device which is mostly

+empty doesn't use 10 GB of space on the pool. However, the filesystem

 will use more space for base images the larger the device

 is.

+The base device size can be increased at daemon restart which will allow

+all future images and containers (based on those new images) to be of the 

+new base device size.

+

+Example use: `docker daemon --storage-opt dm.basesize=50G` 

+

+This will increase the base device size to 50G. The Docker daemon will throw an 

+error if existing base device size is larger than 50G. A user can use 

+this option to expand the base device size however shrinking is not permitted.

+

 This value affects the system-wide "base" empty filesystem that may already

 be initialized and inherited by pulled images. Typically, a change to this

 value requires additional steps to take effect: