@@ -19,12 +19,15 @@ import (

 	"os"

 	"path"

 	"path/filepath"

+	"strings"

 	"syscall"

 	"unsafe"

 	"github.com/docker/docker/daemon/graphdriver"

 	"github.com/docker/docker/pkg/idtools"

 	"github.com/docker/docker/pkg/mount"

+	"github.com/docker/docker/pkg/parsers"

+	"github.com/docker/go-units"

 	"github.com/opencontainers/runc/libcontainer/label"

 )

@@ -32,6 +35,16 @@ func init() {

 	graphdriver.Register("btrfs", Init)

 }

+var (

+	quotaEnabled  = false

+	userDiskQuota = false

+)

+

+type btrfsOptions struct {

+	minSpace uint64

+	size     uint64

+}

+

 // Init returns a new BTRFS driver.

 // An error is returned if BTRFS is not supported.

 func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) {

@@ -57,21 +70,58 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap

 		return nil, err

 	}

+	opt, err := parseOptions(options)

+	if err != nil {

+		return nil, err

+	}

+

+	if userDiskQuota {

+		if err := subvolEnableQuota(home); err != nil {

+			return nil, err

+		}

+		quotaEnabled = true

+	}

+

 	driver := &Driver{

 		home:    home,

 		uidMaps: uidMaps,

 		gidMaps: gidMaps,

+		options: opt,

 	}

 	return graphdriver.NewNaiveDiffDriver(driver, uidMaps, gidMaps), nil

 }

+func parseOptions(opt []string) (btrfsOptions, error) {

+	var options btrfsOptions

+	for _, option := range opt {

+		key, val, err := parsers.ParseKeyValueOpt(option)

+		if err != nil {

+			return options, err

+		}

+		key = strings.ToLower(key)

+		switch key {

+		case "btrfs.min_space":

+			minSpace, err := units.RAMInBytes(val)

+			if err != nil {

+				return options, err

+			}

+			userDiskQuota = true

+			options.minSpace = uint64(minSpace)

+		default:

+			return options, fmt.Errorf("Unknown option %s", key)

+		}

+	}

+	return options, nil

+}

+

 // Driver contains information about the filesystem mounted.

 type Driver struct {

 	//root of the file system

 	home    string

 	uidMaps []idtools.IDMap

 	gidMaps []idtools.IDMap

+	options btrfsOptions

 }

 // String prints the name of the driver (btrfs).

@@ -100,6 +150,12 @@ func (d *Driver) GetMetadata(id string) (map[string]string, error) {

 // Cleanup unmounts the home directory.

 func (d *Driver) Cleanup() error {

+	if quotaEnabled {

+		if err := subvolDisableQuota(d.home); err != nil {

+			return err

+		}

+	}

+

 	return mount.Unmount(d.home)

 }

@@ -238,6 +294,78 @@ func subvolDelete(dirpath, name string) error {

 	return nil

 }

+func subvolEnableQuota(path string) error {

+	dir, err := openDir(path)

+	if err != nil {

+		return err

+	}

+	defer closeDir(dir)

+

+	var args C.struct_btrfs_ioctl_quota_ctl_args

+	args.cmd = C.BTRFS_QUOTA_CTL_ENABLE

+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QUOTA_CTL,

+		uintptr(unsafe.Pointer(&args)))

+	if errno != 0 {

+		return fmt.Errorf("Failed to enable btrfs quota for %s: %v", dir, errno.Error())

+	}

+

+	return nil

+}

+

+func subvolDisableQuota(path string) error {

+	dir, err := openDir(path)

+	if err != nil {

+		return err

+	}

+	defer closeDir(dir)

+

+	var args C.struct_btrfs_ioctl_quota_ctl_args

+	args.cmd = C.BTRFS_QUOTA_CTL_DISABLE

+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QUOTA_CTL,

+		uintptr(unsafe.Pointer(&args)))

+	if errno != 0 {

+		return fmt.Errorf("Failed to disable btrfs quota for %s: %v", dir, errno.Error())

+	}

+

+	return nil

+}

+

+func subvolRescanQuota(path string) error {

+	dir, err := openDir(path)

+	if err != nil {

+		return err

+	}

+	defer closeDir(dir)

+

+	var args C.struct_btrfs_ioctl_quota_rescan_args

+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QUOTA_RESCAN_WAIT,

+		uintptr(unsafe.Pointer(&args)))

+	if errno != 0 {

+		return fmt.Errorf("Failed to rescan btrfs quota for %s: %v", dir, errno.Error())

+	}

+

+	return nil

+}

+

+func subvolLimitQgroup(path string, size uint64) error {

+	dir, err := openDir(path)

+	if err != nil {

+		return err

+	}

+	defer closeDir(dir)

+

+	var args C.struct_btrfs_ioctl_qgroup_limit_args

+	args.lim.max_referenced = C.__u64(size)

+	args.lim.flags = C.BTRFS_QGROUP_LIMIT_MAX_RFER

+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QGROUP_LIMIT,

+		uintptr(unsafe.Pointer(&args)))

+	if errno != 0 {

+		return fmt.Errorf("Failed to limit qgroup for %s: %v", dir, errno.Error())

+	}

+

+	return nil

+}

+

 func (d *Driver) subvolumesDir() string {

 	return path.Join(d.home, "subvolumes")

 }

@@ -254,11 +382,6 @@ func (d *Driver) CreateReadWrite(id, parent, mountLabel string, storageOpt map[s

 // Create the filesystem with given id.

 func (d *Driver) Create(id, parent, mountLabel string, storageOpt map[string]string) error {

-

-	if len(storageOpt) != 0 {

-		return fmt.Errorf("--storage-opt is not supported for btrfs")

-	}

-

 	subvolumes := path.Join(d.home, "subvolumes")

 	rootUID, rootGID, err := idtools.GetRootUIDGID(d.uidMaps, d.gidMaps)

 	if err != nil {

@@ -285,6 +408,16 @@ func (d *Driver) Create(id, parent, mountLabel string, storageOpt map[string]str

 		}

 	}

+	if _, ok := storageOpt["size"]; ok {

+		driver := &Driver{}

+		if err := d.parseStorageOpt(storageOpt, driver); err != nil {

+			return err

+		}

+		if err := d.setStorageSize(path.Join(subvolumes, id), driver); err != nil {

+			return err

+		}

+	}

+

 	// if we have a remapped root (user namespaces enabled), change the created snapshot

 	// dir ownership to match

 	if rootUID != 0 || rootGID != 0 {

@@ -296,6 +429,49 @@ func (d *Driver) Create(id, parent, mountLabel string, storageOpt map[string]str

 	return label.Relabel(path.Join(subvolumes, id), mountLabel, false)

 }

+// Parse btrfs storage options

+func (d *Driver) parseStorageOpt(storageOpt map[string]string, driver *Driver) error {

+	// Read size to change the subvolume disk quota per container

+	for key, val := range storageOpt {

+		key := strings.ToLower(key)

+		switch key {

+		case "size":

+			size, err := units.RAMInBytes(val)

+			if err != nil {

+				return err

+			}

+			driver.options.size = uint64(size)

+		default:

+			return fmt.Errorf("Unknown option %s", key)

+		}

+	}

+

+	return nil

+}

+

+// Set btrfs storage size

+func (d *Driver) setStorageSize(dir string, driver *Driver) error {

+	if driver.options.size <= 0 {

+		return fmt.Errorf("btrfs: invalid storage size: %s", units.HumanSize(float64(driver.options.size)))

+	}

+	if d.options.minSpace > 0 && driver.options.size < d.options.minSpace {

+		return fmt.Errorf("btrfs: storage size cannot be less than %s", units.HumanSize(float64(d.options.minSpace)))

+	}

+

+	if !quotaEnabled {

+		if err := subvolEnableQuota(d.home); err != nil {

+			return err

+		}

+		quotaEnabled = true

+	}

+

+	if err := subvolLimitQgroup(dir, driver.options.size); err != nil {

+		return err

+	}

+

+	return nil

+}

+

 // Remove the filesystem with given id.

 func (d *Driver) Remove(id string) error {

 	dir := d.subvolumesDirID(id)

@@ -308,6 +484,9 @@ func (d *Driver) Remove(id string) error {

 	if err := os.RemoveAll(dir); err != nil && !os.IsNotExist(err) {

 		return err

 	}

+	if err := subvolRescanQuota(d.home); err != nil {

+		return err

+	}

 	return nil

 }

@@ -185,8 +185,10 @@ Linux kernel as of [3.18.0](https://lkml.org/lkml/2014/10/26/137). Call

 ### Storage driver options

 Particular storage-driver can be configured with options specified with

-`--storage-opt` flags. Options for `devicemapper` are prefixed with `dm` and

-options for `zfs` start with `zfs`.

+`--storage-opt` flags. Options for `devicemapper` are prefixed with `dm`,

+options for `zfs` start with `zfs` and options for `btrfs` start with `btrfs`.

+

+#### Devicemapper options

 *  `dm.thinpooldev`

@@ -470,7 +472,7 @@ options for `zfs` start with `zfs`.

     $ dockerd --storage-opt dm.min_free_space=10%

     ```

-Currently supported options of `zfs`:

+#### ZFS options

 * `zfs.fsname`

@@ -482,6 +484,18 @@ Currently supported options of `zfs`:

         $ dockerd -s zfs --storage-opt zfs.fsname=zroot/docker

+#### Btrfs options

+

+* `btrfs.min_space`

+

+    Specifies the mininum size to use when creating the subvolume which is used

+    for containers. If user uses disk quota for btrfs when creating or running

+    a container with **--storage-opt size** option, docker should ensure the

+    **size** cannot be smaller than **btrfs.min_space**.

+

+    Example use:

+        $ docker daemon -s btrfs --storage-opt btrfs.min_space=10G

+

 ## Docker runtime execution options

 The Docker daemon relies on a

@@ -333,6 +333,7 @@ unit, `b` is used. Set LIMIT to `-1` to enable unlimited swap.

    $ docker create -it --storage-opt size=120G fedora /bin/bash

    This (size) will allow to set the container rootfs size to 120G at creation time. User cannot pass a size less than the Default BaseFS Size.

+   This option is only available for the `devicemapper`, `btrfs` and `zfs` graphrivers.

 **--stop-signal**=*SIGTERM*

   Signal to stop a container. Default is SIGTERM.

@@ -484,7 +484,8 @@ its root filesystem mounted as read only prohibiting any writes.

    $ docker run -it --storage-opt size=120G fedora /bin/bash

    This (size) will allow to set the container rootfs size to 120G at creation time. User cannot pass a size less than the Default BaseFS Size.

-  

+   This option is only available for the `devicemapper`, `btrfs` and `zfs` graphrivers.

+

 **--stop-signal**=*SIGTERM*

   Signal to stop a container. Default is SIGTERM.

@@ -247,9 +247,9 @@ backends use operating system level technologies and can be

 configured.

 Specify options to the storage backend with **--storage-opt** flags. The

-backends that currently take options are *devicemapper* and *zfs*.

-Options for *devicemapper* are prefixed with *dm* and options for *zfs*

-start with *zfs*.

+backends that currently take options are *devicemapper*, *zfs* and *btrfs*.

+Options for *devicemapper* are prefixed with *dm*, options for *zfs*

+start with *zfs* and options for *btrfs* start with *btrfs*.

 Specifically for devicemapper, the default is a "loopback" model which

 requires no pre-configuration, but is extremely inefficient.  Do not

@@ -511,6 +511,17 @@ By default docker will pick up the zfs filesystem where docker graph

 Example use: `dockerd -s zfs --storage-opt zfs.fsname=zroot/docker`

+## Btrfs options

+

+#### btrfs.min_space

+

+Specifies the mininum size to use when creating the subvolume which is used

+for containers. If user uses disk quota for btrfs when creating or running

+a container with **--storage-opt size** option, docker should ensure the

+**size** cannot be smaller than **btrfs.min_space**.

+

+Example use: `docker daemon -s btrfs --storage-opt btrfs.min_space=10G`

+

 # CLUSTER STORE OPTIONS

 The daemon uses libkv to advertise