Move graphdrivers into runtime top level pkg

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

runtime/container.go

@@ -7,7 +7,7 @@ import (
 	"github.com/dotcloud/docker/archive"
 	"github.com/dotcloud/docker/engine"
 	"github.com/dotcloud/docker/runtime/execdriver"
-	"github.com/dotcloud/docker/graphdriver"
+	"github.com/dotcloud/docker/runtime/graphdriver"
 	"github.com/dotcloud/docker/image"
 	"github.com/dotcloud/docker/links"
 	"github.com/dotcloud/docker/nat"

runtime/graphdriver/aufs/aufs.go

@@ -0,0 +1,401 @@
+/*
+
+aufs driver directory structure
+
+.
+├── layers // Metadata of layers
+│   ├── 1
+│   ├── 2
+│   └── 3
+├── diffs  // Content of the layer
+│   ├── 1  // Contains layers that need to be mounted for the id
+│   ├── 2
+│   └── 3
+└── mnt    // Mount points for the rw layers to be mounted
+    ├── 1
+    ├── 2
+    └── 3
+
+*/
+
+package aufs
+
+import (
+	"bufio"
+	"fmt"
+	"github.com/dotcloud/docker/archive"
+	"github.com/dotcloud/docker/runtime/graphdriver"
+	mountpk "github.com/dotcloud/docker/pkg/mount"
+	"github.com/dotcloud/docker/utils"
+	"os"
+	"os/exec"
+	"path"
+	"strings"
+	"sync"
+)
+
+var (
+	ErrAufsNotSupported = fmt.Errorf("AUFS was not found in /proc/filesystems")
+)
+
+func init() {
+	graphdriver.Register("aufs", Init)
+}
+
+type Driver struct {
+	root       string
+	sync.Mutex // Protects concurrent modification to active
+	active     map[string]int
+}
+
+// New returns a new AUFS driver.
+// An error is returned if AUFS is not supported.
+func Init(root string) (graphdriver.Driver, error) {
+	// Try to load the aufs kernel module
+	if err := supportsAufs(); err != nil {
+		return nil, err
+	}
+	paths := []string{
+		"mnt",
+		"diff",
+		"layers",
+	}
+
+	a := &Driver{
+		root:   root,
+		active: make(map[string]int),
+	}
+
+	// Create the root aufs driver dir and return
+	// if it already exists
+	// If not populate the dir structure
+	if err := os.MkdirAll(root, 0755); err != nil {
+		if os.IsExist(err) {
+			return a, nil
+		}
+		return nil, err
+	}
+
+	for _, p := range paths {
+		if err := os.MkdirAll(path.Join(root, p), 0755); err != nil {
+			return nil, err
+		}
+	}
+	return a, nil
+}
+
+// Return a nil error if the kernel supports aufs
+// We cannot modprobe because inside dind modprobe fails
+// to run
+func supportsAufs() error {
+	// We can try to modprobe aufs first before looking at
+	// proc/filesystems for when aufs is supported
+	exec.Command("modprobe", "aufs").Run()
+
+	f, err := os.Open("/proc/filesystems")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		if strings.Contains(s.Text(), "aufs") {
+			return nil
+		}
+	}
+	return ErrAufsNotSupported
+}
+
+func (a Driver) rootPath() string {
+	return a.root
+}
+
+func (Driver) String() string {
+	return "aufs"
+}
+
+func (a Driver) Status() [][2]string {
+	ids, _ := loadIds(path.Join(a.rootPath(), "layers"))
+	return [][2]string{
+		{"Root Dir", a.rootPath()},
+		{"Dirs", fmt.Sprintf("%d", len(ids))},
+	}
+}
+
+// Exists returns true if the given id is registered with
+// this driver
+func (a Driver) Exists(id string) bool {
+	if _, err := os.Lstat(path.Join(a.rootPath(), "layers", id)); err != nil {
+		return false
+	}
+	return true
+}
+
+// Three folders are created for each id
+// mnt, layers, and diff
+func (a *Driver) Create(id, parent string) error {
+	if err := a.createDirsFor(id); err != nil {
+		return err
+	}
+	// Write the layers metadata
+	f, err := os.Create(path.Join(a.rootPath(), "layers", id))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	if parent != "" {
+		ids, err := getParentIds(a.rootPath(), parent)
+		if err != nil {
+			return err
+		}
+
+		if _, err := fmt.Fprintln(f, parent); err != nil {
+			return err
+		}
+		for _, i := range ids {
+			if _, err := fmt.Fprintln(f, i); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func (a *Driver) createDirsFor(id string) error {
+	paths := []string{
+		"mnt",
+		"diff",
+	}
+
+	for _, p := range paths {
+		if err := os.MkdirAll(path.Join(a.rootPath(), p, id), 0755); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Unmount and remove the dir information
+func (a *Driver) Remove(id string) error {
+	// Protect the a.active from concurrent access
+	a.Lock()
+	defer a.Unlock()
+
+	if a.active[id] != 0 {
+		utils.Errorf("Warning: removing active id %s\n", id)
+	}
+
+	// Make sure the dir is umounted first
+	if err := a.unmount(id); err != nil {
+		return err
+	}
+	tmpDirs := []string{
+		"mnt",
+		"diff",
+	}
+
+	// Atomically remove each directory in turn by first moving it out of the
+	// way (so that docker doesn't find it anymore) before doing removal of
+	// the whole tree.
+	for _, p := range tmpDirs {
+
+		realPath := path.Join(a.rootPath(), p, id)
+		tmpPath := path.Join(a.rootPath(), p, fmt.Sprintf("%s-removing", id))
+		if err := os.Rename(realPath, tmpPath); err != nil && !os.IsNotExist(err) {
+			return err
+		}
+		defer os.RemoveAll(tmpPath)
+	}
+
+	// Remove the layers file for the id
+	if err := os.Remove(path.Join(a.rootPath(), "layers", id)); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	return nil
+}
+
+// Return the rootfs path for the id
+// This will mount the dir at it's given path
+func (a *Driver) Get(id string) (string, error) {
+	ids, err := getParentIds(a.rootPath(), id)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return "", err
+		}
+		ids = []string{}
+	}
+
+	// Protect the a.active from concurrent access
+	a.Lock()
+	defer a.Unlock()
+
+	count := a.active[id]
+
+	// If a dir does not have a parent ( no layers )do not try to mount
+	// just return the diff path to the data
+	out := path.Join(a.rootPath(), "diff", id)
+	if len(ids) > 0 {
+		out = path.Join(a.rootPath(), "mnt", id)
+
+		if count == 0 {
+			if err := a.mount(id); err != nil {
+				return "", err
+			}
+		}
+	}
+
+	a.active[id] = count + 1
+
+	return out, nil
+}
+
+func (a *Driver) Put(id string) {
+	// Protect the a.active from concurrent access
+	a.Lock()
+	defer a.Unlock()
+
+	if count := a.active[id]; count > 1 {
+		a.active[id] = count - 1
+	} else {
+		ids, _ := getParentIds(a.rootPath(), id)
+		// We only mounted if there are any parents
+		if ids != nil && len(ids) > 0 {
+			a.unmount(id)
+		}
+		delete(a.active, id)
+	}
+}
+
+// Returns an archive of the contents for the id
+func (a *Driver) Diff(id string) (archive.Archive, error) {
+	return archive.TarFilter(path.Join(a.rootPath(), "diff", id), &archive.TarOptions{
+		Compression: archive.Uncompressed,
+	})
+}
+
+func (a *Driver) ApplyDiff(id string, diff archive.ArchiveReader) error {
+	return archive.Untar(diff, path.Join(a.rootPath(), "diff", id), nil)
+}
+
+// Returns the size of the contents for the id
+func (a *Driver) DiffSize(id string) (int64, error) {
+	return utils.TreeSize(path.Join(a.rootPath(), "diff", id))
+}
+
+func (a *Driver) Changes(id string) ([]archive.Change, error) {
+	layers, err := a.getParentLayerPaths(id)
+	if err != nil {
+		return nil, err
+	}
+	return archive.Changes(layers, path.Join(a.rootPath(), "diff", id))
+}
+
+func (a *Driver) getParentLayerPaths(id string) ([]string, error) {
+	parentIds, err := getParentIds(a.rootPath(), id)
+	if err != nil {
+		return nil, err
+	}
+	if len(parentIds) == 0 {
+		return nil, fmt.Errorf("Dir %s does not have any parent layers", id)
+	}
+	layers := make([]string, len(parentIds))
+
+	// Get the diff paths for all the parent ids
+	for i, p := range parentIds {
+		layers[i] = path.Join(a.rootPath(), "diff", p)
+	}
+	return layers, nil
+}
+
+func (a *Driver) mount(id string) error {
+	// If the id is mounted or we get an error return
+	if mounted, err := a.mounted(id); err != nil || mounted {
+		return err
+	}
+
+	var (
+		target = path.Join(a.rootPath(), "mnt", id)
+		rw     = path.Join(a.rootPath(), "diff", id)
+	)
+
+	layers, err := a.getParentLayerPaths(id)
+	if err != nil {
+		return err
+	}
+
+	if err := a.aufsMount(layers, rw, target); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (a *Driver) unmount(id string) error {
+	if mounted, err := a.mounted(id); err != nil || !mounted {
+		return err
+	}
+	target := path.Join(a.rootPath(), "mnt", id)
+	return Unmount(target)
+}
+
+func (a *Driver) mounted(id string) (bool, error) {
+	target := path.Join(a.rootPath(), "mnt", id)
+	return mountpk.Mounted(target)
+}
+
+// During cleanup aufs needs to unmount all mountpoints
+func (a *Driver) Cleanup() error {
+	ids, err := loadIds(path.Join(a.rootPath(), "layers"))
+	if err != nil {
+		return err
+	}
+	for _, id := range ids {
+		if err := a.unmount(id); err != nil {
+			utils.Errorf("Unmounting %s: %s", utils.TruncateID(id), err)
+		}
+	}
+	return nil
+}
+
+func (a *Driver) aufsMount(ro []string, rw, target string) (err error) {
+	defer func() {
+		if err != nil {
+			Unmount(target)
+		}
+	}()
+
+	if err = a.tryMount(ro, rw, target); err != nil {
+		if err = a.mountRw(rw, target); err != nil {
+			return
+		}
+
+		for _, layer := range ro {
+			branch := fmt.Sprintf("append:%s=ro+wh", layer)
+			if err = mount("none", target, "aufs", MsRemount, branch); err != nil {
+				return
+			}
+		}
+	}
+	return
+}
+
+// Try to mount using the aufs fast path, if this fails then
+// append ro layers.
+func (a *Driver) tryMount(ro []string, rw, target string) (err error) {
+	var (
+		rwBranch   = fmt.Sprintf("%s=rw", rw)
+		roBranches = fmt.Sprintf("%s=ro+wh:", strings.Join(ro, "=ro+wh:"))
+	)
+	return mount("none", target, "aufs", 0, fmt.Sprintf("br:%v:%v,xino=/dev/shm/aufs.xino", rwBranch, roBranches))
+}
+
+func (a *Driver) mountRw(rw, target string) error {
+	return mount("none", target, "aufs", 0, fmt.Sprintf("br:%s,xino=/dev/shm/aufs.xino", rw))
+}
+
+func rollbackMount(target string, err error) {
+	if err != nil {
+		Unmount(target)
+	}
+}

runtime/graphdriver/aufs/aufs_test.go

@@ -0,0 +1,697 @@
+package aufs
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"github.com/dotcloud/docker/archive"
+	"github.com/dotcloud/docker/runtime/graphdriver"
+	"io/ioutil"
+	"os"
+	"path"
+	"testing"
+)
+
+var (
+	tmp = path.Join(os.TempDir(), "aufs-tests", "aufs")
+)
+
+func testInit(dir string, t *testing.T) graphdriver.Driver {
+	d, err := Init(dir)
+	if err != nil {
+		if err == ErrAufsNotSupported {
+			t.Skip(err)
+		} else {
+			t.Fatal(err)
+		}
+	}
+	return d
+}
+
+func newDriver(t *testing.T) *Driver {
+	if err := os.MkdirAll(tmp, 0755); err != nil {
+		t.Fatal(err)
+	}
+
+	d := testInit(tmp, t)
+	return d.(*Driver)
+}
+
+func TestNewDriver(t *testing.T) {
+	if err := os.MkdirAll(tmp, 0755); err != nil {
+		t.Fatal(err)
+	}
+
+	d := testInit(tmp, t)
+	defer os.RemoveAll(tmp)
+	if d == nil {
+		t.Fatalf("Driver should not be nil")
+	}
+}
+
+func TestAufsString(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if d.String() != "aufs" {
+		t.Fatalf("Expected aufs got %s", d.String())
+	}
+}
+
+func TestCreateDirStructure(t *testing.T) {
+	newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	paths := []string{
+		"mnt",
+		"layers",
+		"diff",
+	}
+
+	for _, p := range paths {
+		if _, err := os.Stat(path.Join(tmp, p)); err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+// We should be able to create two drivers with the same dir structure
+func TestNewDriverFromExistingDir(t *testing.T) {
+	if err := os.MkdirAll(tmp, 0755); err != nil {
+		t.Fatal(err)
+	}
+
+	testInit(tmp, t)
+	testInit(tmp, t)
+	os.RemoveAll(tmp)
+}
+
+func TestCreateNewDir(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestCreateNewDirStructure(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	paths := []string{
+		"mnt",
+		"diff",
+		"layers",
+	}
+
+	for _, p := range paths {
+		if _, err := os.Stat(path.Join(tmp, p, "1")); err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+func TestRemoveImage(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := d.Remove("1"); err != nil {
+		t.Fatal(err)
+	}
+
+	paths := []string{
+		"mnt",
+		"diff",
+		"layers",
+	}
+
+	for _, p := range paths {
+		if _, err := os.Stat(path.Join(tmp, p, "1")); err == nil {
+			t.Fatalf("Error should not be nil because dirs with id 1 should be delted: %s", p)
+		}
+	}
+}
+
+func TestGetWithoutParent(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	diffPath, err := d.Get("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := path.Join(tmp, "diff", "1")
+	if diffPath != expected {
+		t.Fatalf("Expected path %s got %s", expected, diffPath)
+	}
+}
+
+func TestCleanupWithNoDirs(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Cleanup(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestCleanupWithDir(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := d.Cleanup(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestMountedFalseResponse(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	response, err := d.mounted("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if response != false {
+		t.Fatalf("Response if dir id 1 is mounted should be false")
+	}
+}
+
+func TestMountedTrueReponse(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+	defer d.Cleanup()
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+	if err := d.Create("2", "1"); err != nil {
+		t.Fatal(err)
+	}
+
+	_, err := d.Get("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	response, err := d.mounted("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if response != true {
+		t.Fatalf("Response if dir id 2 is mounted should be true")
+	}
+}
+
+func TestMountWithParent(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+	if err := d.Create("2", "1"); err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() {
+		if err := d.Cleanup(); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	mntPath, err := d.Get("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if mntPath == "" {
+		t.Fatal("mntPath should not be empty string")
+	}
+
+	expected := path.Join(tmp, "mnt", "2")
+	if mntPath != expected {
+		t.Fatalf("Expected %s got %s", expected, mntPath)
+	}
+}
+
+func TestRemoveMountedDir(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+	if err := d.Create("2", "1"); err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() {
+		if err := d.Cleanup(); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	mntPath, err := d.Get("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if mntPath == "" {
+		t.Fatal("mntPath should not be empty string")
+	}
+
+	mounted, err := d.mounted("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !mounted {
+		t.Fatalf("Dir id 2 should be mounted")
+	}
+
+	if err := d.Remove("2"); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestCreateWithInvalidParent(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", "docker"); err == nil {
+		t.Fatalf("Error should not be nil with parent does not exist")
+	}
+}
+
+func TestGetDiff(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	diffPath, err := d.Get("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Add a file to the diff path with a fixed size
+	size := int64(1024)
+
+	f, err := os.Create(path.Join(diffPath, "test_file"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Truncate(size); err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	a, err := d.Diff("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if a == nil {
+		t.Fatalf("Archive should not be nil")
+	}
+}
+
+func TestChanges(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+	if err := d.Create("2", "1"); err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() {
+		if err := d.Cleanup(); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	mntPoint, err := d.Get("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Create a file to save in the mountpoint
+	f, err := os.Create(path.Join(mntPoint, "test.txt"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := f.WriteString("testline"); err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	changes, err := d.Changes("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(changes) != 1 {
+		t.Fatalf("Dir 2 should have one change from parent got %d", len(changes))
+	}
+	change := changes[0]
+
+	expectedPath := "/test.txt"
+	if change.Path != expectedPath {
+		t.Fatalf("Expected path %s got %s", expectedPath, change.Path)
+	}
+
+	if change.Kind != archive.ChangeAdd {
+		t.Fatalf("Change kind should be ChangeAdd got %s", change.Kind)
+	}
+
+	if err := d.Create("3", "2"); err != nil {
+		t.Fatal(err)
+	}
+	mntPoint, err = d.Get("3")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Create a file to save in the mountpoint
+	f, err = os.Create(path.Join(mntPoint, "test2.txt"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := f.WriteString("testline"); err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	changes, err = d.Changes("3")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(changes) != 1 {
+		t.Fatalf("Dir 2 should have one change from parent got %d", len(changes))
+	}
+	change = changes[0]
+
+	expectedPath = "/test2.txt"
+	if change.Path != expectedPath {
+		t.Fatalf("Expected path %s got %s", expectedPath, change.Path)
+	}
+
+	if change.Kind != archive.ChangeAdd {
+		t.Fatalf("Change kind should be ChangeAdd got %s", change.Kind)
+	}
+}
+
+func TestDiffSize(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	diffPath, err := d.Get("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Add a file to the diff path with a fixed size
+	size := int64(1024)
+
+	f, err := os.Create(path.Join(diffPath, "test_file"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Truncate(size); err != nil {
+		t.Fatal(err)
+	}
+	s, err := f.Stat()
+	if err != nil {
+		t.Fatal(err)
+	}
+	size = s.Size()
+	if err := f.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	diffSize, err := d.DiffSize("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if diffSize != size {
+		t.Fatalf("Expected size to be %d got %d", size, diffSize)
+	}
+}
+
+func TestChildDiffSize(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+	defer d.Cleanup()
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	diffPath, err := d.Get("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Add a file to the diff path with a fixed size
+	size := int64(1024)
+
+	f, err := os.Create(path.Join(diffPath, "test_file"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Truncate(size); err != nil {
+		t.Fatal(err)
+	}
+	s, err := f.Stat()
+	if err != nil {
+		t.Fatal(err)
+	}
+	size = s.Size()
+	if err := f.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	diffSize, err := d.DiffSize("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if diffSize != size {
+		t.Fatalf("Expected size to be %d got %d", size, diffSize)
+	}
+
+	if err := d.Create("2", "1"); err != nil {
+		t.Fatal(err)
+	}
+
+	diffSize, err = d.DiffSize("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+	// The diff size for the child should be zero
+	if diffSize != 0 {
+		t.Fatalf("Expected size to be %d got %d", 0, diffSize)
+	}
+}
+
+func TestExists(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+	defer d.Cleanup()
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	if d.Exists("none") {
+		t.Fatal("id name should not exist in the driver")
+	}
+
+	if !d.Exists("1") {
+		t.Fatal("id 1 should exist in the driver")
+	}
+}
+
+func TestStatus(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+	defer d.Cleanup()
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	status := d.Status()
+	if status == nil || len(status) == 0 {
+		t.Fatal("Status should not be nil or empty")
+	}
+	rootDir := status[0]
+	dirs := status[1]
+	if rootDir[0] != "Root Dir" {
+		t.Fatalf("Expected Root Dir got %s", rootDir[0])
+	}
+	if rootDir[1] != d.rootPath() {
+		t.Fatalf("Expected %s got %s", d.rootPath(), rootDir[1])
+	}
+	if dirs[0] != "Dirs" {
+		t.Fatalf("Expected Dirs got %s", dirs[0])
+	}
+	if dirs[1] != "1" {
+		t.Fatalf("Expected 1 got %s", dirs[1])
+	}
+}
+
+func TestApplyDiff(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+	defer d.Cleanup()
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	diffPath, err := d.Get("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Add a file to the diff path with a fixed size
+	size := int64(1024)
+
+	f, err := os.Create(path.Join(diffPath, "test_file"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Truncate(size); err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	diff, err := d.Diff("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := d.Create("2", ""); err != nil {
+		t.Fatal(err)
+	}
+	if err := d.Create("3", "2"); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := d.ApplyDiff("3", diff); err != nil {
+		t.Fatal(err)
+	}
+
+	// Ensure that the file is in the mount point for id 3
+
+	mountPoint, err := d.Get("3")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(path.Join(mountPoint, "test_file")); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func hash(c string) string {
+	h := sha256.New()
+	fmt.Fprint(h, c)
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+func TestMountMoreThan42Layers(t *testing.T) {
+	d := newDriver(t)
+	defer os.RemoveAll(tmp)
+	defer d.Cleanup()
+	var last string
+	var expected int
+
+	for i := 1; i < 127; i++ {
+		expected++
+		var (
+			parent  = fmt.Sprintf("%d", i-1)
+			current = fmt.Sprintf("%d", i)
+		)
+
+		if parent == "0" {
+			parent = ""
+		} else {
+			parent = hash(parent)
+		}
+		current = hash(current)
+
+		if err := d.Create(current, parent); err != nil {
+			t.Logf("Current layer %d", i)
+			t.Fatal(err)
+		}
+		point, err := d.Get(current)
+		if err != nil {
+			t.Logf("Current layer %d", i)
+			t.Fatal(err)
+		}
+		f, err := os.Create(path.Join(point, current))
+		if err != nil {
+			t.Logf("Current layer %d", i)
+			t.Fatal(err)
+		}
+		f.Close()
+
+		if i%10 == 0 {
+			if err := os.Remove(path.Join(point, parent)); err != nil {
+				t.Logf("Current layer %d", i)
+				t.Fatal(err)
+			}
+			expected--
+		}
+		last = current
+	}
+
+	// Perform the actual mount for the top most image
+	point, err := d.Get(last)
+	if err != nil {
+		t.Fatal(err)
+	}
+	files, err := ioutil.ReadDir(point)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(files) != expected {
+		t.Fatalf("Expected %d got %d", expected, len(files))
+	}
+}

runtime/graphdriver/aufs/dirs.go

@@ -0,0 +1,46 @@
+package aufs
+
+import (
+	"bufio"
+	"io/ioutil"
+	"os"
+	"path"
+)
+
+// Return all the directories
+func loadIds(root string) ([]string, error) {
+	dirs, err := ioutil.ReadDir(root)
+	if err != nil {
+		return nil, err
+	}
+	out := []string{}
+	for _, d := range dirs {
+		if !d.IsDir() {
+			out = append(out, d.Name())
+		}
+	}
+	return out, nil
+}
+
+// Read the layers file for the current id and return all the
+// layers represented by new lines in the file
+//
+// If there are no lines in the file then the id has no parent
+// and an empty slice is returned.
+func getParentIds(root, id string) ([]string, error) {
+	f, err := os.Open(path.Join(root, "layers", id))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	out := []string{}
+	s := bufio.NewScanner(f)
+
+	for s.Scan() {
+		if t := s.Text(); t != "" {
+			out = append(out, s.Text())
+		}
+	}
+	return out, s.Err()
+}

runtime/graphdriver/aufs/migrate.go

@@ -0,0 +1,194 @@
+package aufs
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+)
+
+type metadata struct {
+	ID       string `json:"id"`
+	ParentID string `json:"parent,omitempty"`
+	Image    string `json:"Image,omitempty"`
+
+	parent *metadata
+}
+
+func pathExists(pth string) bool {
+	if _, err := os.Stat(pth); err != nil {
+		return false
+	}
+	return true
+}
+
+// Migrate existing images and containers from docker < 0.7.x
+//
+// The format pre 0.7 is for docker to store the metadata and filesystem
+// content in the same directory.  For the migration to work we need to move Image layer
+// data from /var/lib/docker/graph/<id>/layers to the diff of the registered id.
+//
+// Next we need to migrate the container's rw layer to diff of the driver.  After the
+// contents are migrated we need to register the image and container ids with the
+// driver.
+//
+// For the migration we try to move the folder containing the layer files, if that
+// fails because the data is currently mounted we will fallback to creating a
+// symlink.
+func (a *Driver) Migrate(pth string, setupInit func(p string) error) error {
+	if pathExists(path.Join(pth, "graph")) {
+		if err := a.migrateRepositories(pth); err != nil {
+			return err
+		}
+		if err := a.migrateImages(path.Join(pth, "graph")); err != nil {
+			return err
+		}
+		return a.migrateContainers(path.Join(pth, "containers"), setupInit)
+	}
+	return nil
+}
+
+func (a *Driver) migrateRepositories(pth string) error {
+	name := path.Join(pth, "repositories")
+	if err := os.Rename(name, name+"-aufs"); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	return nil
+}
+
+func (a *Driver) migrateContainers(pth string, setupInit func(p string) error) error {
+	fis, err := ioutil.ReadDir(pth)
+	if err != nil {
+		return err
+	}
+
+	for _, fi := range fis {
+		if id := fi.Name(); fi.IsDir() && pathExists(path.Join(pth, id, "rw")) {
+			if err := tryRelocate(path.Join(pth, id, "rw"), path.Join(a.rootPath(), "diff", id)); err != nil {
+				return err
+			}
+
+			if !a.Exists(id) {
+
+				metadata, err := loadMetadata(path.Join(pth, id, "config.json"))
+				if err != nil {
+					return err
+				}
+
+				initID := fmt.Sprintf("%s-init", id)
+				if err := a.Create(initID, metadata.Image); err != nil {
+					return err
+				}
+
+				initPath, err := a.Get(initID)
+				if err != nil {
+					return err
+				}
+				// setup init layer
+				if err := setupInit(initPath); err != nil {
+					return err
+				}
+
+				if err := a.Create(id, initID); err != nil {
+					return err
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func (a *Driver) migrateImages(pth string) error {
+	fis, err := ioutil.ReadDir(pth)
+	if err != nil {
+		return err
+	}
+	var (
+		m       = make(map[string]*metadata)
+		current *metadata
+		exists  bool
+	)
+
+	for _, fi := range fis {
+		if id := fi.Name(); fi.IsDir() && pathExists(path.Join(pth, id, "layer")) {
+			if current, exists = m[id]; !exists {
+				current, err = loadMetadata(path.Join(pth, id, "json"))
+				if err != nil {
+					return err
+				}
+				m[id] = current
+			}
+		}
+	}
+
+	for _, v := range m {
+		v.parent = m[v.ParentID]
+	}
+
+	migrated := make(map[string]bool)
+	for _, v := range m {
+		if err := a.migrateImage(v, pth, migrated); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (a *Driver) migrateImage(m *metadata, pth string, migrated map[string]bool) error {
+	if !migrated[m.ID] {
+		if m.parent != nil {
+			a.migrateImage(m.parent, pth, migrated)
+		}
+		if err := tryRelocate(path.Join(pth, m.ID, "layer"), path.Join(a.rootPath(), "diff", m.ID)); err != nil {
+			return err
+		}
+		if !a.Exists(m.ID) {
+			if err := a.Create(m.ID, m.ParentID); err != nil {
+				return err
+			}
+		}
+		migrated[m.ID] = true
+	}
+	return nil
+}
+
+// tryRelocate will try to rename the old path to the new pack and if
+// the operation fails, it will fallback to a symlink
+func tryRelocate(oldPath, newPath string) error {
+	s, err := os.Lstat(newPath)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	// If the destination is a symlink then we already tried to relocate once before
+	// and it failed so we delete it and try to remove
+	if s != nil && s.Mode()&os.ModeSymlink == os.ModeSymlink {
+		if err := os.RemoveAll(newPath); err != nil {
+			return err
+		}
+	}
+	if err := os.Rename(oldPath, newPath); err != nil {
+		if sErr := os.Symlink(oldPath, newPath); sErr != nil {
+			return fmt.Errorf("Unable to relocate %s to %s: Rename err %s Symlink err %s", oldPath, newPath, err, sErr)
+		}
+	}
+	return nil
+}
+
+func loadMetadata(pth string) (*metadata, error) {
+	f, err := os.Open(pth)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	var (
+		out = &metadata{}
+		dec = json.NewDecoder(f)
+	)
+
+	if err := dec.Decode(out); err != nil {
+		return nil, err
+	}
+	return out, nil
+}

runtime/graphdriver/aufs/mount.go

@@ -0,0 +1,17 @@
+package aufs
+
+import (
+	"github.com/dotcloud/docker/utils"
+	"os/exec"
+	"syscall"
+)
+
+func Unmount(target string) error {
+	if err := exec.Command("auplink", target, "flush").Run(); err != nil {
+		utils.Errorf("[warning]: couldn't run auplink before unmount: %s", err)
+	}
+	if err := syscall.Unmount(target, 0); err != nil {
+		return err
+	}
+	return nil
+}

runtime/graphdriver/aufs/mount_linux.go

@@ -0,0 +1,11 @@
+// +build amd64
+
+package aufs
+
+import "syscall"
+
+const MsRemount = syscall.MS_REMOUNT
+
+func mount(source string, target string, fstype string, flags uintptr, data string) error {
+	return syscall.Mount(source, target, fstype, flags, data)
+}

runtime/graphdriver/aufs/mount_unsupported.go

@@ -0,0 +1,11 @@
+// +build !linux !amd64
+
+package aufs
+
+import "errors"
+
+const MsRemount = 0
+
+func mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
+	return errors.New("mount is not implemented on darwin")
+}

runtime/graphdriver/btrfs/btrfs.go

@@ -0,0 +1,213 @@
+// +build linux,amd64
+
+package btrfs
+
+/*
+#include <stdlib.h>
+#include <dirent.h>
+#include <btrfs/ioctl.h>
+*/
+import "C"
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/runtime/graphdriver"
+	"os"
+	"path"
+	"syscall"
+	"unsafe"
+)
+
+func init() {
+	graphdriver.Register("btrfs", Init)
+}
+
+func Init(home string) (graphdriver.Driver, error) {
+	rootdir := path.Dir(home)
+
+	var buf syscall.Statfs_t
+	if err := syscall.Statfs(rootdir, &buf); err != nil {
+		return nil, err
+	}
+
+	if buf.Type != 0x9123683E {
+		return nil, fmt.Errorf("%s is not a btrfs filesystem", rootdir)
+	}
+
+	return &Driver{
+		home: home,
+	}, nil
+}
+
+type Driver struct {
+	home string
+}
+
+func (d *Driver) String() string {
+	return "btrfs"
+}
+
+func (d *Driver) Status() [][2]string {
+	return nil
+}
+
+func (d *Driver) Cleanup() error {
+	return nil
+}
+
+func free(p *C.char) {
+	C.free(unsafe.Pointer(p))
+}
+
+func openDir(path string) (*C.DIR, error) {
+	Cpath := C.CString(path)
+	defer free(Cpath)
+
+	dir := C.opendir(Cpath)
+	if dir == nil {
+		return nil, fmt.Errorf("Can't open dir")
+	}
+	return dir, nil
+}
+
+func closeDir(dir *C.DIR) {
+	if dir != nil {
+		C.closedir(dir)
+	}
+}
+
+func getDirFd(dir *C.DIR) uintptr {
+	return uintptr(C.dirfd(dir))
+}
+
+func subvolCreate(path, name string) error {
+	dir, err := openDir(path)
+	if err != nil {
+		return err
+	}
+	defer closeDir(dir)
+
+	var args C.struct_btrfs_ioctl_vol_args
+	for i, c := range []byte(name) {
+		args.name[i] = C.char(c)
+	}
+
+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_SUBVOL_CREATE,
+		uintptr(unsafe.Pointer(&args)))
+	if errno != 0 {
+		return fmt.Errorf("Failed to create btrfs subvolume: %v", errno.Error())
+	}
+	return nil
+}
+
+func subvolSnapshot(src, dest, name string) error {
+	srcDir, err := openDir(src)
+	if err != nil {
+		return err
+	}
+	defer closeDir(srcDir)
+
+	destDir, err := openDir(dest)
+	if err != nil {
+		return err
+	}
+	defer closeDir(destDir)
+
+	var args C.struct_btrfs_ioctl_vol_args_v2
+	args.fd = C.__s64(getDirFd(srcDir))
+	for i, c := range []byte(name) {
+		args.name[i] = C.char(c)
+	}
+
+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(destDir), C.BTRFS_IOC_SNAP_CREATE_V2,
+		uintptr(unsafe.Pointer(&args)))
+	if errno != 0 {
+		return fmt.Errorf("Failed to create btrfs snapshot: %v", errno.Error())
+	}
+	return nil
+}
+
+func subvolDelete(path, name string) error {
+	dir, err := openDir(path)
+	if err != nil {
+		return err
+	}
+	defer closeDir(dir)
+
+	var args C.struct_btrfs_ioctl_vol_args
+	for i, c := range []byte(name) {
+		args.name[i] = C.char(c)
+	}
+
+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_SNAP_DESTROY,
+		uintptr(unsafe.Pointer(&args)))
+	if errno != 0 {
+		return fmt.Errorf("Failed to destroy btrfs snapshot: %v", errno.Error())
+	}
+	return nil
+}
+
+func (d *Driver) subvolumesDir() string {
+	return path.Join(d.home, "subvolumes")
+}
+
+func (d *Driver) subvolumesDirId(id string) string {
+	return path.Join(d.subvolumesDir(), id)
+}
+
+func (d *Driver) Create(id string, parent string) error {
+	subvolumes := path.Join(d.home, "subvolumes")
+	if err := os.MkdirAll(subvolumes, 0700); err != nil {
+		return err
+	}
+	if parent == "" {
+		if err := subvolCreate(subvolumes, id); err != nil {
+			return err
+		}
+	} else {
+		parentDir, err := d.Get(parent)
+		if err != nil {
+			return err
+		}
+		if err := subvolSnapshot(parentDir, subvolumes, id); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (d *Driver) Remove(id string) error {
+	dir := d.subvolumesDirId(id)
+	if _, err := os.Stat(dir); err != nil {
+		return err
+	}
+	if err := subvolDelete(d.subvolumesDir(), id); err != nil {
+		return err
+	}
+	return os.RemoveAll(dir)
+}
+
+func (d *Driver) Get(id string) (string, error) {
+	dir := d.subvolumesDirId(id)
+	st, err := os.Stat(dir)
+	if err != nil {
+		return "", err
+	}
+
+	if !st.IsDir() {
+		return "", fmt.Errorf("%s: not a directory", dir)
+	}
+
+	return dir, nil
+}
+
+func (d *Driver) Put(id string) {
+	// Get() creates no runtime resources (like e.g. mounts)
+	// so this doesn't need to do anything.
+}
+
+func (d *Driver) Exists(id string) bool {
+	dir := d.subvolumesDirId(id)
+	_, err := os.Stat(dir)
+	return err == nil
+}

runtime/graphdriver/btrfs/dummy_unsupported.go

@@ -0,0 +1,3 @@
+// +build !linux !amd64
+
+package btrfs

runtime/graphdriver/devmapper/attach_loopback.go

@@ -0,0 +1,126 @@
+// +build linux,amd64
+
+package devmapper
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/utils"
+)
+
+func stringToLoopName(src string) [LoNameSize]uint8 {
+	var dst [LoNameSize]uint8
+	copy(dst[:], src[:])
+	return dst
+}
+
+func getNextFreeLoopbackIndex() (int, error) {
+	f, err := osOpenFile("/dev/loop-control", osORdOnly, 0644)
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+
+	index, err := ioctlLoopCtlGetFree(f.Fd())
+	if index < 0 {
+		index = 0
+	}
+	return index, err
+}
+
+func openNextAvailableLoopback(index int, sparseFile *osFile) (loopFile *osFile, err error) {
+	// Start looking for a free /dev/loop
+	for {
+		target := fmt.Sprintf("/dev/loop%d", index)
+		index++
+
+		fi, err := osStat(target)
+		if err != nil {
+			if osIsNotExist(err) {
+				utils.Errorf("There are no more loopback device available.")
+			}
+			return nil, ErrAttachLoopbackDevice
+		}
+
+		if fi.Mode()&osModeDevice != osModeDevice {
+			utils.Errorf("Loopback device %s is not a block device.", target)
+			continue
+		}
+
+		// OpenFile adds O_CLOEXEC
+		loopFile, err = osOpenFile(target, osORdWr, 0644)
+		if err != nil {
+			utils.Errorf("Error openning loopback device: %s", err)
+			return nil, ErrAttachLoopbackDevice
+		}
+
+		// Try to attach to the loop file
+		if err := ioctlLoopSetFd(loopFile.Fd(), sparseFile.Fd()); err != nil {
+			loopFile.Close()
+
+			// If the error is EBUSY, then try the next loopback
+			if err != sysEBusy {
+				utils.Errorf("Cannot set up loopback device %s: %s", target, err)
+				return nil, ErrAttachLoopbackDevice
+			}
+
+			// Otherwise, we keep going with the loop
+			continue
+		}
+		// In case of success, we finished. Break the loop.
+		break
+	}
+
+	// This can't happen, but let's be sure
+	if loopFile == nil {
+		utils.Errorf("Unreachable code reached! Error attaching %s to a loopback device.", sparseFile.Name())
+		return nil, ErrAttachLoopbackDevice
+	}
+
+	return loopFile, nil
+}
+
+// attachLoopDevice attaches the given sparse file to the next
+// available loopback device. It returns an opened *osFile.
+func attachLoopDevice(sparseName string) (loop *osFile, err error) {
+
+	// Try to retrieve the next available loopback device via syscall.
+	// If it fails, we discard error and start loopking for a
+	// loopback from index 0.
+	startIndex, err := getNextFreeLoopbackIndex()
+	if err != nil {
+		utils.Debugf("Error retrieving the next available loopback: %s", err)
+	}
+
+	// OpenFile adds O_CLOEXEC
+	sparseFile, err := osOpenFile(sparseName, osORdWr, 0644)
+	if err != nil {
+		utils.Errorf("Error openning sparse file %s: %s", sparseName, err)
+		return nil, ErrAttachLoopbackDevice
+	}
+	defer sparseFile.Close()
+
+	loopFile, err := openNextAvailableLoopback(startIndex, sparseFile)
+	if err != nil {
+		return nil, err
+	}
+
+	// Set the status of the loopback device
+	loopInfo := &LoopInfo64{
+		loFileName: stringToLoopName(loopFile.Name()),
+		loOffset:   0,
+		loFlags:    LoFlagsAutoClear,
+	}
+
+	if err := ioctlLoopSetStatus64(loopFile.Fd(), loopInfo); err != nil {
+		utils.Errorf("Cannot set up loopback device info: %s", err)
+
+		// If the call failed, then free the loopback device
+		if err := ioctlLoopClrFd(loopFile.Fd()); err != nil {
+			utils.Errorf("Error while cleaning up the loopback device")
+		}
+		loopFile.Close()
+		return nil, ErrAttachLoopbackDevice
+	}
+
+	return loopFile, nil
+}

runtime/graphdriver/devmapper/devmapper.go

@@ -0,0 +1,595 @@
+// +build linux,amd64
+
+package devmapper
+
+import (
+	"errors"
+	"fmt"
+	"github.com/dotcloud/docker/utils"
+	"runtime"
+	"syscall"
+)
+
+type DevmapperLogger interface {
+	log(level int, file string, line int, dmError int, message string)
+}
+
+const (
+	DeviceCreate TaskType = iota
+	DeviceReload
+	DeviceRemove
+	DeviceRemoveAll
+	DeviceSuspend
+	DeviceResume
+	DeviceInfo
+	DeviceDeps
+	DeviceRename
+	DeviceVersion
+	DeviceStatus
+	DeviceTable
+	DeviceWaitevent
+	DeviceList
+	DeviceClear
+	DeviceMknodes
+	DeviceListVersions
+	DeviceTargetMsg
+	DeviceSetGeometry
+)
+
+const (
+	AddNodeOnResume AddNodeType = iota
+	AddNodeOnCreate
+)
+
+var (
+	ErrTaskRun                = errors.New("dm_task_run failed")
+	ErrTaskSetName            = errors.New("dm_task_set_name failed")
+	ErrTaskSetMessage         = errors.New("dm_task_set_message failed")
+	ErrTaskSetAddNode         = errors.New("dm_task_set_add_node failed")
+	ErrTaskSetRo              = errors.New("dm_task_set_ro failed")
+	ErrTaskAddTarget          = errors.New("dm_task_add_target failed")
+	ErrTaskSetSector          = errors.New("dm_task_set_sector failed")
+	ErrTaskGetInfo            = errors.New("dm_task_get_info failed")
+	ErrTaskSetCookie          = errors.New("dm_task_set_cookie failed")
+	ErrNilCookie              = errors.New("cookie ptr can't be nil")
+	ErrAttachLoopbackDevice   = errors.New("loopback mounting failed")
+	ErrGetBlockSize           = errors.New("Can't get block size")
+	ErrUdevWait               = errors.New("wait on udev cookie failed")
+	ErrSetDevDir              = errors.New("dm_set_dev_dir failed")
+	ErrGetLibraryVersion      = errors.New("dm_get_library_version failed")
+	ErrCreateRemoveTask       = errors.New("Can't create task of type DeviceRemove")
+	ErrRunRemoveDevice        = errors.New("running removeDevice failed")
+	ErrInvalidAddNode         = errors.New("Invalide AddNoce type")
+	ErrGetLoopbackBackingFile = errors.New("Unable to get loopback backing file")
+	ErrLoopbackSetCapacity    = errors.New("Unable set loopback capacity")
+)
+
+type (
+	Task struct {
+		unmanaged *CDmTask
+	}
+	Info struct {
+		Exists        int
+		Suspended     int
+		LiveTable     int
+		InactiveTable int
+		OpenCount     int32
+		EventNr       uint32
+		Major         uint32
+		Minor         uint32
+		ReadOnly      int
+		TargetCount   int32
+	}
+	TaskType    int
+	AddNodeType int
+)
+
+func (t *Task) destroy() {
+	if t != nil {
+		DmTaskDestroy(t.unmanaged)
+		runtime.SetFinalizer(t, nil)
+	}
+}
+
+func TaskCreate(tasktype TaskType) *Task {
+	Ctask := DmTaskCreate(int(tasktype))
+	if Ctask == nil {
+		return nil
+	}
+	task := &Task{unmanaged: Ctask}
+	runtime.SetFinalizer(task, (*Task).destroy)
+	return task
+}
+
+func (t *Task) Run() error {
+	if res := DmTaskRun(t.unmanaged); res != 1 {
+		return ErrTaskRun
+	}
+	return nil
+}
+
+func (t *Task) SetName(name string) error {
+	if res := DmTaskSetName(t.unmanaged, name); res != 1 {
+		return ErrTaskSetName
+	}
+	return nil
+}
+
+func (t *Task) SetMessage(message string) error {
+	if res := DmTaskSetMessage(t.unmanaged, message); res != 1 {
+		return ErrTaskSetMessage
+	}
+	return nil
+}
+
+func (t *Task) SetSector(sector uint64) error {
+	if res := DmTaskSetSector(t.unmanaged, sector); res != 1 {
+		return ErrTaskSetSector
+	}
+	return nil
+}
+
+func (t *Task) SetCookie(cookie *uint, flags uint16) error {
+	if cookie == nil {
+		return ErrNilCookie
+	}
+	if res := DmTaskSetCookie(t.unmanaged, cookie, flags); res != 1 {
+		return ErrTaskSetCookie
+	}
+	return nil
+}
+
+func (t *Task) SetAddNode(addNode AddNodeType) error {
+	if addNode != AddNodeOnResume && addNode != AddNodeOnCreate {
+		return ErrInvalidAddNode
+	}
+	if res := DmTaskSetAddNode(t.unmanaged, addNode); res != 1 {
+		return ErrTaskSetAddNode
+	}
+	return nil
+}
+
+func (t *Task) SetRo() error {
+	if res := DmTaskSetRo(t.unmanaged); res != 1 {
+		return ErrTaskSetRo
+	}
+	return nil
+}
+
+func (t *Task) AddTarget(start, size uint64, ttype, params string) error {
+	if res := DmTaskAddTarget(t.unmanaged, start, size,
+		ttype, params); res != 1 {
+		return ErrTaskAddTarget
+	}
+	return nil
+}
+
+func (t *Task) GetInfo() (*Info, error) {
+	info := &Info{}
+	if res := DmTaskGetInfo(t.unmanaged, info); res != 1 {
+		return nil, ErrTaskGetInfo
+	}
+	return info, nil
+}
+
+func (t *Task) GetNextTarget(next uintptr) (nextPtr uintptr, start uint64,
+	length uint64, targetType string, params string) {
+
+	return DmGetNextTarget(t.unmanaged, next, &start, &length,
+			&targetType, &params),
+		start, length, targetType, params
+}
+
+func getLoopbackBackingFile(file *osFile) (uint64, uint64, error) {
+	loopInfo, err := ioctlLoopGetStatus64(file.Fd())
+	if err != nil {
+		utils.Errorf("Error get loopback backing file: %s\n", err)
+		return 0, 0, ErrGetLoopbackBackingFile
+	}
+	return loopInfo.loDevice, loopInfo.loInode, nil
+}
+
+func LoopbackSetCapacity(file *osFile) error {
+	if err := ioctlLoopSetCapacity(file.Fd(), 0); err != nil {
+		utils.Errorf("Error loopbackSetCapacity: %s", err)
+		return ErrLoopbackSetCapacity
+	}
+	return nil
+}
+
+func FindLoopDeviceFor(file *osFile) *osFile {
+	stat, err := file.Stat()
+	if err != nil {
+		return nil
+	}
+	targetInode := stat.Sys().(*sysStatT).Ino
+	targetDevice := stat.Sys().(*sysStatT).Dev
+
+	for i := 0; true; i++ {
+		path := fmt.Sprintf("/dev/loop%d", i)
+
+		file, err := osOpenFile(path, osORdWr, 0)
+		if err != nil {
+			if osIsNotExist(err) {
+				return nil
+			}
+
+			// Ignore all errors until the first not-exist
+			// we want to continue looking for the file
+			continue
+		}
+
+		dev, inode, err := getLoopbackBackingFile(file)
+		if err == nil && dev == targetDevice && inode == targetInode {
+			return file
+		}
+		file.Close()
+	}
+
+	return nil
+}
+
+func UdevWait(cookie uint) error {
+	if res := DmUdevWait(cookie); res != 1 {
+		utils.Debugf("Failed to wait on udev cookie %d", cookie)
+		return ErrUdevWait
+	}
+	return nil
+}
+
+func LogInitVerbose(level int) {
+	DmLogInitVerbose(level)
+}
+
+var dmLogger DevmapperLogger = nil
+
+func logInit(logger DevmapperLogger) {
+	dmLogger = logger
+	LogWithErrnoInit()
+}
+
+func SetDevDir(dir string) error {
+	if res := DmSetDevDir(dir); res != 1 {
+		utils.Debugf("Error dm_set_dev_dir")
+		return ErrSetDevDir
+	}
+	return nil
+}
+
+func GetLibraryVersion() (string, error) {
+	var version string
+	if res := DmGetLibraryVersion(&version); res != 1 {
+		return "", ErrGetLibraryVersion
+	}
+	return version, nil
+}
+
+// Useful helper for cleanup
+func RemoveDevice(name string) error {
+	task := TaskCreate(DeviceRemove)
+	if task == nil {
+		return ErrCreateRemoveTask
+	}
+	if err := task.SetName(name); err != nil {
+		utils.Debugf("Can't set task name %s", name)
+		return err
+	}
+	if err := task.Run(); err != nil {
+		return ErrRunRemoveDevice
+	}
+	return nil
+}
+
+func GetBlockDeviceSize(file *osFile) (uint64, error) {
+	size, err := ioctlBlkGetSize64(file.Fd())
+	if err != nil {
+		utils.Errorf("Error getblockdevicesize: %s", err)
+		return 0, ErrGetBlockSize
+	}
+	return uint64(size), nil
+}
+
+func BlockDeviceDiscard(path string) error {
+	file, err := osOpenFile(path, osORdWr, 0)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	size, err := GetBlockDeviceSize(file)
+	if err != nil {
+		return err
+	}
+
+	if err := ioctlBlkDiscard(file.Fd(), 0, size); err != nil {
+		return err
+	}
+
+	// Without this sometimes the remove of the device that happens after
+	// discard fails with EBUSY.
+	syscall.Sync()
+
+	return nil
+}
+
+// This is the programmatic example of "dmsetup create"
+func createPool(poolName string, dataFile, metadataFile *osFile) error {
+	task, err := createTask(DeviceCreate, poolName)
+	if task == nil {
+		return err
+	}
+
+	size, err := GetBlockDeviceSize(dataFile)
+	if err != nil {
+		return fmt.Errorf("Can't get data size")
+	}
+
+	params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768 1 skip_block_zeroing"
+	if err := task.AddTarget(0, size/512, "thin-pool", params); err != nil {
+		return fmt.Errorf("Can't add target")
+	}
+
+	var cookie uint = 0
+	if err := task.SetCookie(&cookie, 0); err != nil {
+		return fmt.Errorf("Can't set cookie")
+	}
+
+	if err := task.Run(); err != nil {
+		return fmt.Errorf("Error running DeviceCreate (createPool)")
+	}
+
+	UdevWait(cookie)
+
+	return nil
+}
+
+func reloadPool(poolName string, dataFile, metadataFile *osFile) error {
+	task, err := createTask(DeviceReload, poolName)
+	if task == nil {
+		return err
+	}
+
+	size, err := GetBlockDeviceSize(dataFile)
+	if err != nil {
+		return fmt.Errorf("Can't get data size")
+	}
+
+	params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768"
+	if err := task.AddTarget(0, size/512, "thin-pool", params); err != nil {
+		return fmt.Errorf("Can't add target")
+	}
+
+	if err := task.Run(); err != nil {
+		return fmt.Errorf("Error running DeviceCreate")
+	}
+
+	return nil
+}
+
+func createTask(t TaskType, name string) (*Task, error) {
+	task := TaskCreate(t)
+	if task == nil {
+		return nil, fmt.Errorf("Can't create task of type %d", int(t))
+	}
+	if err := task.SetName(name); err != nil {
+		return nil, fmt.Errorf("Can't set task name %s", name)
+	}
+	return task, nil
+}
+
+func getInfo(name string) (*Info, error) {
+	task, err := createTask(DeviceInfo, name)
+	if task == nil {
+		return nil, err
+	}
+	if err := task.Run(); err != nil {
+		return nil, err
+	}
+	return task.GetInfo()
+}
+
+func getStatus(name string) (uint64, uint64, string, string, error) {
+	task, err := createTask(DeviceStatus, name)
+	if task == nil {
+		utils.Debugf("getStatus: Error createTask: %s", err)
+		return 0, 0, "", "", err
+	}
+	if err := task.Run(); err != nil {
+		utils.Debugf("getStatus: Error Run: %s", err)
+		return 0, 0, "", "", err
+	}
+
+	devinfo, err := task.GetInfo()
+	if err != nil {
+		utils.Debugf("getStatus: Error GetInfo: %s", err)
+		return 0, 0, "", "", err
+	}
+	if devinfo.Exists == 0 {
+		utils.Debugf("getStatus: Non existing device %s", name)
+		return 0, 0, "", "", fmt.Errorf("Non existing device %s", name)
+	}
+
+	_, start, length, targetType, params := task.GetNextTarget(0)
+	return start, length, targetType, params, nil
+}
+
+func setTransactionId(poolName string, oldId uint64, newId uint64) error {
+	task, err := createTask(DeviceTargetMsg, poolName)
+	if task == nil {
+		return err
+	}
+
+	if err := task.SetSector(0); err != nil {
+		return fmt.Errorf("Can't set sector")
+	}
+
+	if err := task.SetMessage(fmt.Sprintf("set_transaction_id %d %d", oldId, newId)); err != nil {
+		return fmt.Errorf("Can't set message")
+	}
+
+	if err := task.Run(); err != nil {
+		return fmt.Errorf("Error running setTransactionId")
+	}
+	return nil
+}
+
+func suspendDevice(name string) error {
+	task, err := createTask(DeviceSuspend, name)
+	if task == nil {
+		return err
+	}
+	if err := task.Run(); err != nil {
+		return fmt.Errorf("Error running DeviceSuspend: %s", err)
+	}
+	return nil
+}
+
+func resumeDevice(name string) error {
+	task, err := createTask(DeviceResume, name)
+	if task == nil {
+		return err
+	}
+
+	var cookie uint = 0
+	if err := task.SetCookie(&cookie, 0); err != nil {
+		return fmt.Errorf("Can't set cookie")
+	}
+
+	if err := task.Run(); err != nil {
+		return fmt.Errorf("Error running DeviceResume")
+	}
+
+	UdevWait(cookie)
+
+	return nil
+}
+
+func createDevice(poolName string, deviceId int) error {
+	utils.Debugf("[devmapper] createDevice(poolName=%v, deviceId=%v)", poolName, deviceId)
+	task, err := createTask(DeviceTargetMsg, poolName)
+	if task == nil {
+		return err
+	}
+
+	if err := task.SetSector(0); err != nil {
+		return fmt.Errorf("Can't set sector")
+	}
+
+	if err := task.SetMessage(fmt.Sprintf("create_thin %d", deviceId)); err != nil {
+		return fmt.Errorf("Can't set message")
+	}
+
+	if err := task.Run(); err != nil {
+		return fmt.Errorf("Error running createDevice")
+	}
+	return nil
+}
+
+func deleteDevice(poolName string, deviceId int) error {
+	task, err := createTask(DeviceTargetMsg, poolName)
+	if task == nil {
+		return err
+	}
+
+	if err := task.SetSector(0); err != nil {
+		return fmt.Errorf("Can't set sector")
+	}
+
+	if err := task.SetMessage(fmt.Sprintf("delete %d", deviceId)); err != nil {
+		return fmt.Errorf("Can't set message")
+	}
+
+	if err := task.Run(); err != nil {
+		return fmt.Errorf("Error running deleteDevice")
+	}
+	return nil
+}
+
+func removeDevice(name string) error {
+	utils.Debugf("[devmapper] removeDevice START")
+	defer utils.Debugf("[devmapper] removeDevice END")
+	task, err := createTask(DeviceRemove, name)
+	if task == nil {
+		return err
+	}
+	if err = task.Run(); err != nil {
+		return fmt.Errorf("Error running removeDevice")
+	}
+	return nil
+}
+
+func activateDevice(poolName string, name string, deviceId int, size uint64) error {
+	task, err := createTask(DeviceCreate, name)
+	if task == nil {
+		return err
+	}
+
+	params := fmt.Sprintf("%s %d", poolName, deviceId)
+	if err := task.AddTarget(0, size/512, "thin", params); err != nil {
+		return fmt.Errorf("Can't add target")
+	}
+	if err := task.SetAddNode(AddNodeOnCreate); err != nil {
+		return fmt.Errorf("Can't add node")
+	}
+
+	var cookie uint = 0
+	if err := task.SetCookie(&cookie, 0); err != nil {
+		return fmt.Errorf("Can't set cookie")
+	}
+
+	if err := task.Run(); err != nil {
+		return fmt.Errorf("Error running DeviceCreate (activateDevice)")
+	}
+
+	UdevWait(cookie)
+
+	return nil
+}
+
+func (devices *DeviceSet) createSnapDevice(poolName string, deviceId int, baseName string, baseDeviceId int) error {
+	devinfo, _ := getInfo(baseName)
+	doSuspend := devinfo != nil && devinfo.Exists != 0
+
+	if doSuspend {
+		if err := suspendDevice(baseName); err != nil {
+			return err
+		}
+	}
+
+	task, err := createTask(DeviceTargetMsg, poolName)
+	if task == nil {
+		if doSuspend {
+			resumeDevice(baseName)
+		}
+		return err
+	}
+
+	if err := task.SetSector(0); err != nil {
+		if doSuspend {
+			resumeDevice(baseName)
+		}
+		return fmt.Errorf("Can't set sector")
+	}
+
+	if err := task.SetMessage(fmt.Sprintf("create_snap %d %d", deviceId, baseDeviceId)); err != nil {
+		if doSuspend {
+			resumeDevice(baseName)
+		}
+		return fmt.Errorf("Can't set message")
+	}
+
+	if err := task.Run(); err != nil {
+		if doSuspend {
+			resumeDevice(baseName)
+		}
+		return fmt.Errorf("Error running DeviceCreate (createSnapDevice)")
+	}
+
+	if doSuspend {
+		if err := resumeDevice(baseName); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

runtime/graphdriver/devmapper/devmapper_doc.go

@@ -0,0 +1,106 @@
+package devmapper
+
+// Definition of struct dm_task and sub structures (from lvm2)
+//
+// struct dm_ioctl {
+// 	/*
+// 	 * The version number is made up of three parts:
+// 	 * major - no backward or forward compatibility,
+// 	 * minor - only backwards compatible,
+// 	 * patch - both backwards and forwards compatible.
+// 	 *
+// 	 * All clients of the ioctl interface should fill in the
+// 	 * version number of the interface that they were
+// 	 * compiled with.
+// 	 *
+// 	 * All recognised ioctl commands (ie. those that don't
+// 	 * return -ENOTTY) fill out this field, even if the
+// 	 * command failed.
+// 	 */
+// 	uint32_t version[3];	/* in/out */
+// 	uint32_t data_size;	/* total size of data passed in
+// 				 * including this struct */
+
+// 	uint32_t data_start;	/* offset to start of data
+// 				 * relative to start of this struct */
+
+// 	uint32_t target_count;	/* in/out */
+// 	int32_t open_count;	/* out */
+// 	uint32_t flags;		/* in/out */
+
+// 	/*
+// 	 * event_nr holds either the event number (input and output) or the
+// 	 * udev cookie value (input only).
+// 	 * The DM_DEV_WAIT ioctl takes an event number as input.
+// 	 * The DM_SUSPEND, DM_DEV_REMOVE and DM_DEV_RENAME ioctls
+// 	 * use the field as a cookie to return in the DM_COOKIE
+// 	 * variable with the uevents they issue.
+// 	 * For output, the ioctls return the event number, not the cookie.
+// 	 */
+// 	uint32_t event_nr;      	/* in/out */
+// 	uint32_t padding;
+
+// 	uint64_t dev;		/* in/out */
+
+// 	char name[DM_NAME_LEN];	/* device name */
+// 	char uuid[DM_UUID_LEN];	/* unique identifier for
+// 				 * the block device */
+// 	char data[7];		/* padding or data */
+// };
+
+// struct target {
+// 	uint64_t start;
+// 	uint64_t length;
+// 	char *type;
+// 	char *params;
+
+// 	struct target *next;
+// };
+
+// typedef enum {
+// 	DM_ADD_NODE_ON_RESUME, /* add /dev/mapper node with dmsetup resume */
+// 	DM_ADD_NODE_ON_CREATE  /* add /dev/mapper node with dmsetup create */
+// } dm_add_node_t;
+
+// struct dm_task {
+// 	int type;
+// 	char *dev_name;
+// 	char *mangled_dev_name;
+
+// 	struct target *head, *tail;
+
+// 	int read_only;
+// 	uint32_t event_nr;
+// 	int major;
+// 	int minor;
+// 	int allow_default_major_fallback;
+// 	uid_t uid;
+// 	gid_t gid;
+// 	mode_t mode;
+// 	uint32_t read_ahead;
+// 	uint32_t read_ahead_flags;
+// 	union {
+// 		struct dm_ioctl *v4;
+// 	} dmi;
+// 	char *newname;
+// 	char *message;
+// 	char *geometry;
+// 	uint64_t sector;
+// 	int no_flush;
+// 	int no_open_count;
+// 	int skip_lockfs;
+// 	int query_inactive_table;
+// 	int suppress_identical_reload;
+// 	dm_add_node_t add_node;
+// 	uint64_t existing_table_size;
+// 	int cookie_set;
+// 	int new_uuid;
+// 	int secure_data;
+// 	int retry_remove;
+// 	int enable_checks;
+// 	int expected_errno;
+
+// 	char *uuid;
+// 	char *mangled_uuid;
+// };
+//

runtime/graphdriver/devmapper/devmapper_log.go

@@ -0,0 +1,15 @@
+// +build linux,amd64
+
+package devmapper
+
+import "C"
+
+// Due to the way cgo works this has to be in a separate file, as devmapper.go has
+// definitions in the cgo block, which is incompatible with using "//export"
+
+//export DevmapperLogCallback
+func DevmapperLogCallback(level C.int, file *C.char, line C.int, dm_errno_or_class C.int, message *C.char) {
+	if dmLogger != nil {
+		dmLogger.log(int(level), C.GoString(file), int(line), int(dm_errno_or_class), C.GoString(message))
+	}
+}

runtime/graphdriver/devmapper/devmapper_test.go

@@ -0,0 +1,287 @@
+// +build linux,amd64
+
+package devmapper
+
+import (
+	"testing"
+)
+
+func TestTaskCreate(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	// Test success
+	taskCreate(t, DeviceInfo)
+
+	// Test Failure
+	DmTaskCreate = dmTaskCreateFail
+	defer func() { DmTaskCreate = dmTaskCreateFct }()
+	if task := TaskCreate(-1); task != nil {
+		t.Fatalf("An error should have occured while creating an invalid task.")
+	}
+}
+
+func TestTaskRun(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	task := taskCreate(t, DeviceInfo)
+
+	// Test success
+	// Perform the RUN
+	if err := task.Run(); err != nil {
+		t.Fatal(err)
+	}
+	// Make sure we don't have error with GetInfo
+	if _, err := task.GetInfo(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Test failure
+	DmTaskRun = dmTaskRunFail
+	defer func() { DmTaskRun = dmTaskRunFct }()
+
+	task = taskCreate(t, DeviceInfo)
+	// Perform the RUN
+	if err := task.Run(); err != ErrTaskRun {
+		t.Fatalf("An error should have occured while running task.")
+	}
+	// Make sure GetInfo also fails
+	if _, err := task.GetInfo(); err != ErrTaskGetInfo {
+		t.Fatalf("GetInfo should fail if task.Run() failed.")
+	}
+}
+
+func TestTaskSetName(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	task := taskCreate(t, DeviceInfo)
+
+	// Test success
+	if err := task.SetName("test"); err != nil {
+		t.Fatal(err)
+	}
+
+	// Test failure
+	DmTaskSetName = dmTaskSetNameFail
+	defer func() { DmTaskSetName = dmTaskSetNameFct }()
+
+	if err := task.SetName("test"); err != ErrTaskSetName {
+		t.Fatalf("An error should have occured while runnign SetName.")
+	}
+}
+
+func TestTaskSetMessage(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	task := taskCreate(t, DeviceInfo)
+
+	// Test success
+	if err := task.SetMessage("test"); err != nil {
+		t.Fatal(err)
+	}
+
+	// Test failure
+	DmTaskSetMessage = dmTaskSetMessageFail
+	defer func() { DmTaskSetMessage = dmTaskSetMessageFct }()
+
+	if err := task.SetMessage("test"); err != ErrTaskSetMessage {
+		t.Fatalf("An error should have occured while runnign SetMessage.")
+	}
+}
+
+func TestTaskSetSector(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	task := taskCreate(t, DeviceInfo)
+
+	// Test success
+	if err := task.SetSector(128); err != nil {
+		t.Fatal(err)
+	}
+
+	DmTaskSetSector = dmTaskSetSectorFail
+	defer func() { DmTaskSetSector = dmTaskSetSectorFct }()
+
+	// Test failure
+	if err := task.SetSector(0); err != ErrTaskSetSector {
+		t.Fatalf("An error should have occured while running SetSector.")
+	}
+}
+
+func TestTaskSetCookie(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	var (
+		cookie uint = 0
+		task        = taskCreate(t, DeviceInfo)
+	)
+
+	// Test success
+	if err := task.SetCookie(&cookie, 0); err != nil {
+		t.Fatal(err)
+	}
+
+	// Test failure
+	if err := task.SetCookie(nil, 0); err != ErrNilCookie {
+		t.Fatalf("An error should have occured while running SetCookie with nil cookie.")
+	}
+
+	DmTaskSetCookie = dmTaskSetCookieFail
+	defer func() { DmTaskSetCookie = dmTaskSetCookieFct }()
+
+	if err := task.SetCookie(&cookie, 0); err != ErrTaskSetCookie {
+		t.Fatalf("An error should have occured while running SetCookie.")
+	}
+}
+
+func TestTaskSetAddNode(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	task := taskCreate(t, DeviceInfo)
+
+	// Test success
+	if err := task.SetAddNode(0); err != nil {
+		t.Fatal(err)
+	}
+
+	// Test failure
+	if err := task.SetAddNode(-1); err != ErrInvalidAddNode {
+		t.Fatalf("An error should have occured running SetAddNode with wrong node.")
+	}
+
+	DmTaskSetAddNode = dmTaskSetAddNodeFail
+	defer func() { DmTaskSetAddNode = dmTaskSetAddNodeFct }()
+
+	if err := task.SetAddNode(0); err != ErrTaskSetAddNode {
+		t.Fatalf("An error should have occured running SetAddNode.")
+	}
+}
+
+func TestTaskSetRo(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	task := taskCreate(t, DeviceInfo)
+
+	// Test success
+	if err := task.SetRo(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Test failure
+	DmTaskSetRo = dmTaskSetRoFail
+	defer func() { DmTaskSetRo = dmTaskSetRoFct }()
+
+	if err := task.SetRo(); err != ErrTaskSetRo {
+		t.Fatalf("An error should have occured running SetRo.")
+	}
+}
+
+func TestTaskAddTarget(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	task := taskCreate(t, DeviceInfo)
+
+	// Test success
+	if err := task.AddTarget(0, 128, "thinp", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	// Test failure
+	DmTaskAddTarget = dmTaskAddTargetFail
+	defer func() { DmTaskAddTarget = dmTaskAddTargetFct }()
+
+	if err := task.AddTarget(0, 128, "thinp", ""); err != ErrTaskAddTarget {
+		t.Fatalf("An error should have occured running AddTarget.")
+	}
+}
+
+// func TestTaskGetInfo(t *testing.T) {
+// 	task := taskCreate(t, DeviceInfo)
+
+// 	// Test success
+// 	if _, err := task.GetInfo(); err != nil {
+// 		t.Fatal(err)
+// 	}
+
+// 	// Test failure
+// 	DmTaskGetInfo = dmTaskGetInfoFail
+// 	defer func() { DmTaskGetInfo = dmTaskGetInfoFct }()
+
+// 	if _, err := task.GetInfo(); err != ErrTaskGetInfo {
+// 		t.Fatalf("An error should have occured running GetInfo.")
+// 	}
+// }
+
+// func TestTaskGetNextTarget(t *testing.T) {
+// 	task := taskCreate(t, DeviceInfo)
+
+// 	if next, _, _, _, _ := task.GetNextTarget(0); next == 0 {
+// 		t.Fatalf("The next target should not be 0.")
+// 	}
+// }
+
+/// Utils
+func taskCreate(t *testing.T, taskType TaskType) *Task {
+	task := TaskCreate(taskType)
+	if task == nil {
+		t.Fatalf("Error creating task")
+	}
+	return task
+}
+
+/// Failure function replacement
+func dmTaskCreateFail(t int) *CDmTask {
+	return nil
+}
+
+func dmTaskRunFail(task *CDmTask) int {
+	return -1
+}
+
+func dmTaskSetNameFail(task *CDmTask, name string) int {
+	return -1
+}
+
+func dmTaskSetMessageFail(task *CDmTask, message string) int {
+	return -1
+}
+
+func dmTaskSetSectorFail(task *CDmTask, sector uint64) int {
+	return -1
+}
+
+func dmTaskSetCookieFail(task *CDmTask, cookie *uint, flags uint16) int {
+	return -1
+}
+
+func dmTaskSetAddNodeFail(task *CDmTask, addNode AddNodeType) int {
+	return -1
+}
+
+func dmTaskSetRoFail(task *CDmTask) int {
+	return -1
+}
+
+func dmTaskAddTargetFail(task *CDmTask,
+	start, size uint64, ttype, params string) int {
+	return -1
+}
+
+func dmTaskGetInfoFail(task *CDmTask, info *Info) int {
+	return -1
+}
+
+func dmGetNextTargetFail(task *CDmTask, next uintptr, start, length *uint64,
+	target, params *string) uintptr {
+	return 0
+}
+
+func dmAttachLoopDeviceFail(filename string, fd *int) string {
+	return ""
+}
+
+func sysGetBlockSizeFail(fd uintptr, size *uint64) sysErrno {
+	return 1
+}
+
+func dmUdevWaitFail(cookie uint) int {
+	return -1
+}
+
+func dmSetDevDirFail(dir string) int {
+	return -1
+}
+
+func dmGetLibraryVersionFail(version *string) int {
+	return -1
+}

runtime/graphdriver/devmapper/devmapper_wrapper.go

@@ -0,0 +1,229 @@
+// +build linux,amd64
+
+package devmapper
+
+/*
+#cgo LDFLAGS: -L. -ldevmapper
+#include <libdevmapper.h>
+#include <linux/loop.h> // FIXME: present only for defines, maybe we can remove it?
+#include <linux/fs.h>   // FIXME: present only for BLKGETSIZE64, maybe we can remove it?
+
+#ifndef LOOP_CTL_GET_FREE
+  #define LOOP_CTL_GET_FREE 0x4C82
+#endif
+
+#ifndef LO_FLAGS_PARTSCAN
+  #define LO_FLAGS_PARTSCAN 8
+#endif
+
+// FIXME: Can't we find a way to do the logging in pure Go?
+extern void DevmapperLogCallback(int level, char *file, int line, int dm_errno_or_class, char *str);
+
+static void	log_cb(int level, const char *file, int line, int dm_errno_or_class, const char *f, ...)
+{
+  char buffer[256];
+  va_list ap;
+
+  va_start(ap, f);
+  vsnprintf(buffer, 256, f, ap);
+  va_end(ap);
+
+  DevmapperLogCallback(level, (char *)file, line, dm_errno_or_class, buffer);
+}
+
+static void	log_with_errno_init()
+{
+  dm_log_with_errno_init(log_cb);
+}
+*/
+import "C"
+
+import (
+	"unsafe"
+)
+
+type (
+	CDmTask C.struct_dm_task
+
+	CLoopInfo64 C.struct_loop_info64
+	LoopInfo64  struct {
+		loDevice           uint64 /* ioctl r/o */
+		loInode            uint64 /* ioctl r/o */
+		loRdevice          uint64 /* ioctl r/o */
+		loOffset           uint64
+		loSizelimit        uint64 /* bytes, 0 == max available */
+		loNumber           uint32 /* ioctl r/o */
+		loEncrypt_type     uint32
+		loEncrypt_key_size uint32 /* ioctl w/o */
+		loFlags            uint32 /* ioctl r/o */
+		loFileName         [LoNameSize]uint8
+		loCryptName        [LoNameSize]uint8
+		loEncryptKey       [LoKeySize]uint8 /* ioctl w/o */
+		loInit             [2]uint64
+	}
+)
+
+// IOCTL consts
+const (
+	BlkGetSize64 = C.BLKGETSIZE64
+	BlkDiscard   = C.BLKDISCARD
+
+	LoopSetFd       = C.LOOP_SET_FD
+	LoopCtlGetFree  = C.LOOP_CTL_GET_FREE
+	LoopGetStatus64 = C.LOOP_GET_STATUS64
+	LoopSetStatus64 = C.LOOP_SET_STATUS64
+	LoopClrFd       = C.LOOP_CLR_FD
+	LoopSetCapacity = C.LOOP_SET_CAPACITY
+)
+
+const (
+	LoFlagsAutoClear = C.LO_FLAGS_AUTOCLEAR
+	LoFlagsReadOnly  = C.LO_FLAGS_READ_ONLY
+	LoFlagsPartScan  = C.LO_FLAGS_PARTSCAN
+	LoKeySize        = C.LO_KEY_SIZE
+	LoNameSize       = C.LO_NAME_SIZE
+)
+
+var (
+	DmGetLibraryVersion = dmGetLibraryVersionFct
+	DmGetNextTarget     = dmGetNextTargetFct
+	DmLogInitVerbose    = dmLogInitVerboseFct
+	DmSetDevDir         = dmSetDevDirFct
+	DmTaskAddTarget     = dmTaskAddTargetFct
+	DmTaskCreate        = dmTaskCreateFct
+	DmTaskDestroy       = dmTaskDestroyFct
+	DmTaskGetInfo       = dmTaskGetInfoFct
+	DmTaskRun           = dmTaskRunFct
+	DmTaskSetAddNode    = dmTaskSetAddNodeFct
+	DmTaskSetCookie     = dmTaskSetCookieFct
+	DmTaskSetMessage    = dmTaskSetMessageFct
+	DmTaskSetName       = dmTaskSetNameFct
+	DmTaskSetRo         = dmTaskSetRoFct
+	DmTaskSetSector     = dmTaskSetSectorFct
+	DmUdevWait          = dmUdevWaitFct
+	LogWithErrnoInit    = logWithErrnoInitFct
+)
+
+func free(p *C.char) {
+	C.free(unsafe.Pointer(p))
+}
+
+func dmTaskDestroyFct(task *CDmTask) {
+	C.dm_task_destroy((*C.struct_dm_task)(task))
+}
+
+func dmTaskCreateFct(taskType int) *CDmTask {
+	return (*CDmTask)(C.dm_task_create(C.int(taskType)))
+}
+
+func dmTaskRunFct(task *CDmTask) int {
+	ret, _ := C.dm_task_run((*C.struct_dm_task)(task))
+	return int(ret)
+}
+
+func dmTaskSetNameFct(task *CDmTask, name string) int {
+	Cname := C.CString(name)
+	defer free(Cname)
+
+	return int(C.dm_task_set_name((*C.struct_dm_task)(task), Cname))
+}
+
+func dmTaskSetMessageFct(task *CDmTask, message string) int {
+	Cmessage := C.CString(message)
+	defer free(Cmessage)
+
+	return int(C.dm_task_set_message((*C.struct_dm_task)(task), Cmessage))
+}
+
+func dmTaskSetSectorFct(task *CDmTask, sector uint64) int {
+	return int(C.dm_task_set_sector((*C.struct_dm_task)(task), C.uint64_t(sector)))
+}
+
+func dmTaskSetCookieFct(task *CDmTask, cookie *uint, flags uint16) int {
+	cCookie := C.uint32_t(*cookie)
+	defer func() {
+		*cookie = uint(cCookie)
+	}()
+	return int(C.dm_task_set_cookie((*C.struct_dm_task)(task), &cCookie, C.uint16_t(flags)))
+}
+
+func dmTaskSetAddNodeFct(task *CDmTask, addNode AddNodeType) int {
+	return int(C.dm_task_set_add_node((*C.struct_dm_task)(task), C.dm_add_node_t(addNode)))
+}
+
+func dmTaskSetRoFct(task *CDmTask) int {
+	return int(C.dm_task_set_ro((*C.struct_dm_task)(task)))
+}
+
+func dmTaskAddTargetFct(task *CDmTask,
+	start, size uint64, ttype, params string) int {
+
+	Cttype := C.CString(ttype)
+	defer free(Cttype)
+
+	Cparams := C.CString(params)
+	defer free(Cparams)
+
+	return int(C.dm_task_add_target((*C.struct_dm_task)(task), C.uint64_t(start), C.uint64_t(size), Cttype, Cparams))
+}
+
+func dmTaskGetInfoFct(task *CDmTask, info *Info) int {
+	Cinfo := C.struct_dm_info{}
+	defer func() {
+		info.Exists = int(Cinfo.exists)
+		info.Suspended = int(Cinfo.suspended)
+		info.LiveTable = int(Cinfo.live_table)
+		info.InactiveTable = int(Cinfo.inactive_table)
+		info.OpenCount = int32(Cinfo.open_count)
+		info.EventNr = uint32(Cinfo.event_nr)
+		info.Major = uint32(Cinfo.major)
+		info.Minor = uint32(Cinfo.minor)
+		info.ReadOnly = int(Cinfo.read_only)
+		info.TargetCount = int32(Cinfo.target_count)
+	}()
+	return int(C.dm_task_get_info((*C.struct_dm_task)(task), &Cinfo))
+}
+
+func dmGetNextTargetFct(task *CDmTask, next uintptr, start, length *uint64, target, params *string) uintptr {
+	var (
+		Cstart, Clength      C.uint64_t
+		CtargetType, Cparams *C.char
+	)
+	defer func() {
+		*start = uint64(Cstart)
+		*length = uint64(Clength)
+		*target = C.GoString(CtargetType)
+		*params = C.GoString(Cparams)
+	}()
+
+	nextp := C.dm_get_next_target((*C.struct_dm_task)(task), unsafe.Pointer(next), &Cstart, &Clength, &CtargetType, &Cparams)
+	return uintptr(nextp)
+}
+
+func dmUdevWaitFct(cookie uint) int {
+	return int(C.dm_udev_wait(C.uint32_t(cookie)))
+}
+
+func dmLogInitVerboseFct(level int) {
+	C.dm_log_init_verbose(C.int(level))
+}
+
+func logWithErrnoInitFct() {
+	C.log_with_errno_init()
+}
+
+func dmSetDevDirFct(dir string) int {
+	Cdir := C.CString(dir)
+	defer free(Cdir)
+
+	return int(C.dm_set_dev_dir(Cdir))
+}
+
+func dmGetLibraryVersionFct(version *string) int {
+	buffer := C.CString(string(make([]byte, 128)))
+	defer free(buffer)
+	defer func() {
+		*version = C.GoString(buffer)
+	}()
+	return int(C.dm_get_library_version(buffer, 128))
+}

runtime/graphdriver/devmapper/driver.go

@@ -0,0 +1,143 @@
+// +build linux,amd64
+
+package devmapper
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/runtime/graphdriver"
+	"github.com/dotcloud/docker/utils"
+	"io/ioutil"
+	"os"
+	"path"
+)
+
+func init() {
+	graphdriver.Register("devicemapper", Init)
+}
+
+// Placeholder interfaces, to be replaced
+// at integration.
+
+// End of placeholder interfaces.
+
+type Driver struct {
+	*DeviceSet
+	home string
+}
+
+var Init = func(home string) (graphdriver.Driver, error) {
+	deviceSet, err := NewDeviceSet(home, true)
+	if err != nil {
+		return nil, err
+	}
+	d := &Driver{
+		DeviceSet: deviceSet,
+		home:      home,
+	}
+	return d, nil
+}
+
+func (d *Driver) String() string {
+	return "devicemapper"
+}
+
+func (d *Driver) Status() [][2]string {
+	s := d.DeviceSet.Status()
+
+	status := [][2]string{
+		{"Pool Name", s.PoolName},
+		{"Data file", s.DataLoopback},
+		{"Metadata file", s.MetadataLoopback},
+		{"Data Space Used", fmt.Sprintf("%.1f Mb", float64(s.Data.Used)/(1024*1024))},
+		{"Data Space Total", fmt.Sprintf("%.1f Mb", float64(s.Data.Total)/(1024*1024))},
+		{"Metadata Space Used", fmt.Sprintf("%.1f Mb", float64(s.Metadata.Used)/(1024*1024))},
+		{"Metadata Space Total", fmt.Sprintf("%.1f Mb", float64(s.Metadata.Total)/(1024*1024))},
+	}
+	return status
+}
+
+func (d *Driver) Cleanup() error {
+	return d.DeviceSet.Shutdown()
+}
+
+func (d *Driver) Create(id, parent string) error {
+	if err := d.DeviceSet.AddDevice(id, parent); err != nil {
+		return err
+	}
+
+	mp := path.Join(d.home, "mnt", id)
+	if err := d.mount(id, mp); err != nil {
+		return err
+	}
+
+	if err := osMkdirAll(path.Join(mp, "rootfs"), 0755); err != nil && !osIsExist(err) {
+		return err
+	}
+
+	// Create an "id" file with the container/image id in it to help reconscruct this in case
+	// of later problems
+	if err := ioutil.WriteFile(path.Join(mp, "id"), []byte(id), 0600); err != nil {
+		return err
+	}
+
+	// We float this reference so that the next Get call can
+	// steal it, so we don't have to unmount
+	if err := d.DeviceSet.UnmountDevice(id, UnmountFloat); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (d *Driver) Remove(id string) error {
+	if !d.DeviceSet.HasDevice(id) {
+		// Consider removing a non-existing device a no-op
+		// This is useful to be able to progress on container removal
+		// if the underlying device has gone away due to earlier errors
+		return nil
+	}
+
+	// Sink the float from create in case no Get() call was made
+	if err := d.DeviceSet.UnmountDevice(id, UnmountSink); err != nil {
+		return err
+	}
+	// This assumes the device has been properly Get/Put:ed and thus is unmounted
+	if err := d.DeviceSet.DeleteDevice(id); err != nil {
+		return err
+	}
+
+	mp := path.Join(d.home, "mnt", id)
+	if err := os.RemoveAll(mp); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
+	return nil
+}
+
+func (d *Driver) Get(id string) (string, error) {
+	mp := path.Join(d.home, "mnt", id)
+	if err := d.mount(id, mp); err != nil {
+		return "", err
+	}
+
+	return path.Join(mp, "rootfs"), nil
+}
+
+func (d *Driver) Put(id string) {
+	if err := d.DeviceSet.UnmountDevice(id, UnmountRegular); err != nil {
+		utils.Errorf("Warning: error unmounting device %s: %s\n", id, err)
+	}
+}
+
+func (d *Driver) mount(id, mountPoint string) error {
+	// Create the target directories if they don't exist
+	if err := osMkdirAll(mountPoint, 0755); err != nil && !osIsExist(err) {
+		return err
+	}
+	// Mount the device
+	return d.DeviceSet.MountDevice(id, mountPoint)
+}
+
+func (d *Driver) Exists(id string) bool {
+	return d.Devices[id] != nil
+}

runtime/graphdriver/devmapper/driver_test.go

@@ -0,0 +1,886 @@
+// +build linux,amd64
+
+package devmapper
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/runtime/graphdriver"
+	"io/ioutil"
+	"path"
+	"runtime"
+	"strings"
+	"syscall"
+	"testing"
+)
+
+func init() {
+	// Reduce the size the the base fs and loopback for the tests
+	DefaultDataLoopbackSize = 300 * 1024 * 1024
+	DefaultMetaDataLoopbackSize = 200 * 1024 * 1024
+	DefaultBaseFsSize = 300 * 1024 * 1024
+}
+
+// denyAllDevmapper mocks all calls to libdevmapper in the unit tests, and denies them by default
+func denyAllDevmapper() {
+	// Hijack all calls to libdevmapper with default panics.
+	// Authorized calls are selectively hijacked in each tests.
+	DmTaskCreate = func(t int) *CDmTask {
+		panic("DmTaskCreate: this method should not be called here")
+	}
+	DmTaskRun = func(task *CDmTask) int {
+		panic("DmTaskRun: this method should not be called here")
+	}
+	DmTaskSetName = func(task *CDmTask, name string) int {
+		panic("DmTaskSetName: this method should not be called here")
+	}
+	DmTaskSetMessage = func(task *CDmTask, message string) int {
+		panic("DmTaskSetMessage: this method should not be called here")
+	}
+	DmTaskSetSector = func(task *CDmTask, sector uint64) int {
+		panic("DmTaskSetSector: this method should not be called here")
+	}
+	DmTaskSetCookie = func(task *CDmTask, cookie *uint, flags uint16) int {
+		panic("DmTaskSetCookie: this method should not be called here")
+	}
+	DmTaskSetAddNode = func(task *CDmTask, addNode AddNodeType) int {
+		panic("DmTaskSetAddNode: this method should not be called here")
+	}
+	DmTaskSetRo = func(task *CDmTask) int {
+		panic("DmTaskSetRo: this method should not be called here")
+	}
+	DmTaskAddTarget = func(task *CDmTask, start, size uint64, ttype, params string) int {
+		panic("DmTaskAddTarget: this method should not be called here")
+	}
+	DmTaskGetInfo = func(task *CDmTask, info *Info) int {
+		panic("DmTaskGetInfo: this method should not be called here")
+	}
+	DmGetNextTarget = func(task *CDmTask, next uintptr, start, length *uint64, target, params *string) uintptr {
+		panic("DmGetNextTarget: this method should not be called here")
+	}
+	DmUdevWait = func(cookie uint) int {
+		panic("DmUdevWait: this method should not be called here")
+	}
+	DmSetDevDir = func(dir string) int {
+		panic("DmSetDevDir: this method should not be called here")
+	}
+	DmGetLibraryVersion = func(version *string) int {
+		panic("DmGetLibraryVersion: this method should not be called here")
+	}
+	DmLogInitVerbose = func(level int) {
+		panic("DmLogInitVerbose: this method should not be called here")
+	}
+	DmTaskDestroy = func(task *CDmTask) {
+		panic("DmTaskDestroy: this method should not be called here")
+	}
+	LogWithErrnoInit = func() {
+		panic("LogWithErrnoInit: this method should not be called here")
+	}
+}
+
+func denyAllSyscall() {
+	sysMount = func(source, target, fstype string, flags uintptr, data string) (err error) {
+		panic("sysMount: this method should not be called here")
+	}
+	sysUnmount = func(target string, flags int) (err error) {
+		panic("sysUnmount: this method should not be called here")
+	}
+	sysCloseOnExec = func(fd int) {
+		panic("sysCloseOnExec: this method should not be called here")
+	}
+	sysSyscall = func(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
+		panic("sysSyscall: this method should not be called here")
+	}
+	// Not a syscall, but forbidding it here anyway
+	Mounted = func(mnt string) (bool, error) {
+		panic("devmapper.Mounted: this method should not be called here")
+	}
+	// osOpenFile = os.OpenFile
+	// osNewFile = os.NewFile
+	// osCreate = os.Create
+	// osStat = os.Stat
+	// osIsNotExist = os.IsNotExist
+	// osIsExist = os.IsExist
+	// osMkdirAll = os.MkdirAll
+	// osRemoveAll = os.RemoveAll
+	// osRename = os.Rename
+	// osReadlink = os.Readlink
+
+	// execRun = func(name string, args ...string) error {
+	// 	return exec.Command(name, args...).Run()
+	// }
+}
+
+func mkTestDirectory(t *testing.T) string {
+	dir, err := ioutil.TempDir("", "docker-test-devmapper-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	return dir
+}
+
+func newDriver(t *testing.T) *Driver {
+	home := mkTestDirectory(t)
+	d, err := Init(home)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return d.(*Driver)
+}
+
+func cleanup(d *Driver) {
+	d.Cleanup()
+	osRemoveAll(d.home)
+}
+
+type Set map[string]bool
+
+func (r Set) Assert(t *testing.T, names ...string) {
+	for _, key := range names {
+		required := true
+		if strings.HasPrefix(key, "?") {
+			key = key[1:]
+			required = false
+		}
+		if _, exists := r[key]; !exists && required {
+			t.Fatalf("Key not set: %s", key)
+		}
+		delete(r, key)
+	}
+	if len(r) != 0 {
+		t.Fatalf("Unexpected keys: %v", r)
+	}
+}
+
+func TestInit(t *testing.T) {
+	var (
+		calls        = make(Set)
+		taskMessages = make(Set)
+		taskTypes    = make(Set)
+		home         = mkTestDirectory(t)
+	)
+	defer osRemoveAll(home)
+
+	func() {
+		denyAllDevmapper()
+		DmSetDevDir = func(dir string) int {
+			calls["DmSetDevDir"] = true
+			expectedDir := "/dev"
+			if dir != expectedDir {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmSetDevDir(%v)\nReceived: DmSetDevDir(%v)\n", expectedDir, dir)
+			}
+			return 0
+		}
+		LogWithErrnoInit = func() {
+			calls["DmLogWithErrnoInit"] = true
+		}
+		var task1 CDmTask
+		DmTaskCreate = func(taskType int) *CDmTask {
+			calls["DmTaskCreate"] = true
+			taskTypes[fmt.Sprintf("%d", taskType)] = true
+			return &task1
+		}
+		DmTaskSetName = func(task *CDmTask, name string) int {
+			calls["DmTaskSetName"] = true
+			expectedTask := &task1
+			if task != expectedTask {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskSetName(%v)\nReceived: DmTaskSetName(%v)\n", expectedTask, task)
+			}
+			// FIXME: use Set.AssertRegexp()
+			if !strings.HasPrefix(name, "docker-") && !strings.HasPrefix(name, "/dev/mapper/docker-") ||
+				!strings.HasSuffix(name, "-pool") && !strings.HasSuffix(name, "-base") {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskSetName(%v)\nReceived: DmTaskSetName(%v)\n", "docker-...-pool", name)
+			}
+			return 1
+		}
+		DmTaskRun = func(task *CDmTask) int {
+			calls["DmTaskRun"] = true
+			expectedTask := &task1
+			if task != expectedTask {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskRun(%v)\nReceived: DmTaskRun(%v)\n", expectedTask, task)
+			}
+			return 1
+		}
+		DmTaskGetInfo = func(task *CDmTask, info *Info) int {
+			calls["DmTaskGetInfo"] = true
+			expectedTask := &task1
+			if task != expectedTask {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskGetInfo(%v)\nReceived: DmTaskGetInfo(%v)\n", expectedTask, task)
+			}
+			// This will crash if info is not dereferenceable
+			info.Exists = 0
+			return 1
+		}
+		DmTaskSetSector = func(task *CDmTask, sector uint64) int {
+			calls["DmTaskSetSector"] = true
+			expectedTask := &task1
+			if task != expectedTask {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskSetSector(%v)\nReceived: DmTaskSetSector(%v)\n", expectedTask, task)
+			}
+			if expectedSector := uint64(0); sector != expectedSector {
+				t.Fatalf("Wrong libdevmapper call to DmTaskSetSector\nExpected: %v\nReceived: %v\n", expectedSector, sector)
+			}
+			return 1
+		}
+		DmTaskSetMessage = func(task *CDmTask, message string) int {
+			calls["DmTaskSetMessage"] = true
+			expectedTask := &task1
+			if task != expectedTask {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskSetSector(%v)\nReceived: DmTaskSetSector(%v)\n", expectedTask, task)
+			}
+			taskMessages[message] = true
+			return 1
+		}
+		DmTaskDestroy = func(task *CDmTask) {
+			calls["DmTaskDestroy"] = true
+			expectedTask := &task1
+			if task != expectedTask {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskDestroy(%v)\nReceived: DmTaskDestroy(%v)\n", expectedTask, task)
+			}
+		}
+		DmTaskAddTarget = func(task *CDmTask, start, size uint64, ttype, params string) int {
+			calls["DmTaskSetTarget"] = true
+			expectedTask := &task1
+			if task != expectedTask {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskDestroy(%v)\nReceived: DmTaskDestroy(%v)\n", expectedTask, task)
+			}
+			if start != 0 {
+				t.Fatalf("Wrong start: %d != %d", start, 0)
+			}
+			if ttype != "thin" && ttype != "thin-pool" {
+				t.Fatalf("Wrong ttype: %s", ttype)
+			}
+			// Quick smoke test
+			if params == "" {
+				t.Fatalf("Params should not be empty")
+			}
+			return 1
+		}
+		fakeCookie := uint(4321)
+		DmTaskSetCookie = func(task *CDmTask, cookie *uint, flags uint16) int {
+			calls["DmTaskSetCookie"] = true
+			expectedTask := &task1
+			if task != expectedTask {
+				t.Fatalf("Wrong libdevmapper call\nExpected: DmTaskDestroy(%v)\nReceived: DmTaskDestroy(%v)\n", expectedTask, task)
+			}
+			if flags != 0 {
+				t.Fatalf("Cookie flags should be 0 (not %x)", flags)
+			}
+			*cookie = fakeCookie
+			return 1
+		}
+		DmUdevWait = func(cookie uint) int {
+			calls["DmUdevWait"] = true
+			if cookie != fakeCookie {
+				t.Fatalf("Wrong cookie: %d != %d", cookie, fakeCookie)
+			}
+			return 1
+		}
+		DmTaskSetAddNode = func(task *CDmTask, addNode AddNodeType) int {
+			if addNode != AddNodeOnCreate {
+				t.Fatalf("Wrong AddNoteType: %v (expected %v)", addNode, AddNodeOnCreate)
+			}
+			calls["DmTaskSetAddNode"] = true
+			return 1
+		}
+		execRun = func(name string, args ...string) error {
+			calls["execRun"] = true
+			if name != "mkfs.ext4" {
+				t.Fatalf("Expected %s to be executed, not %s", "mkfs.ext4", name)
+			}
+			return nil
+		}
+		driver, err := Init(home)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer func() {
+			if err := driver.Cleanup(); err != nil {
+				t.Fatal(err)
+			}
+		}()
+	}()
+	// Put all tests in a function to make sure the garbage collection will
+	// occur.
+
+	// Call GC to cleanup runtime.Finalizers
+	runtime.GC()
+
+	calls.Assert(t,
+		"DmSetDevDir",
+		"DmLogWithErrnoInit",
+		"DmTaskSetName",
+		"DmTaskRun",
+		"DmTaskGetInfo",
+		"DmTaskDestroy",
+		"execRun",
+		"DmTaskCreate",
+		"DmTaskSetTarget",
+		"DmTaskSetCookie",
+		"DmUdevWait",
+		"DmTaskSetSector",
+		"DmTaskSetMessage",
+		"DmTaskSetAddNode",
+	)
+	taskTypes.Assert(t, "0", "6", "17")
+	taskMessages.Assert(t, "create_thin 0", "set_transaction_id 0 1")
+}
+
+func fakeInit() func(home string) (graphdriver.Driver, error) {
+	oldInit := Init
+	Init = func(home string) (graphdriver.Driver, error) {
+		return &Driver{
+			home: home,
+		}, nil
+	}
+	return oldInit
+}
+
+func restoreInit(init func(home string) (graphdriver.Driver, error)) {
+	Init = init
+}
+
+func mockAllDevmapper(calls Set) {
+	DmSetDevDir = func(dir string) int {
+		calls["DmSetDevDir"] = true
+		return 0
+	}
+	LogWithErrnoInit = func() {
+		calls["DmLogWithErrnoInit"] = true
+	}
+	DmTaskCreate = func(taskType int) *CDmTask {
+		calls["DmTaskCreate"] = true
+		return &CDmTask{}
+	}
+	DmTaskSetName = func(task *CDmTask, name string) int {
+		calls["DmTaskSetName"] = true
+		return 1
+	}
+	DmTaskRun = func(task *CDmTask) int {
+		calls["DmTaskRun"] = true
+		return 1
+	}
+	DmTaskGetInfo = func(task *CDmTask, info *Info) int {
+		calls["DmTaskGetInfo"] = true
+		return 1
+	}
+	DmTaskSetSector = func(task *CDmTask, sector uint64) int {
+		calls["DmTaskSetSector"] = true
+		return 1
+	}
+	DmTaskSetMessage = func(task *CDmTask, message string) int {
+		calls["DmTaskSetMessage"] = true
+		return 1
+	}
+	DmTaskDestroy = func(task *CDmTask) {
+		calls["DmTaskDestroy"] = true
+	}
+	DmTaskAddTarget = func(task *CDmTask, start, size uint64, ttype, params string) int {
+		calls["DmTaskSetTarget"] = true
+		return 1
+	}
+	DmTaskSetCookie = func(task *CDmTask, cookie *uint, flags uint16) int {
+		calls["DmTaskSetCookie"] = true
+		return 1
+	}
+	DmUdevWait = func(cookie uint) int {
+		calls["DmUdevWait"] = true
+		return 1
+	}
+	DmTaskSetAddNode = func(task *CDmTask, addNode AddNodeType) int {
+		calls["DmTaskSetAddNode"] = true
+		return 1
+	}
+	execRun = func(name string, args ...string) error {
+		calls["execRun"] = true
+		return nil
+	}
+}
+
+func TestDriverName(t *testing.T) {
+	denyAllDevmapper()
+	defer denyAllDevmapper()
+
+	oldInit := fakeInit()
+	defer restoreInit(oldInit)
+
+	d := newDriver(t)
+	if d.String() != "devicemapper" {
+		t.Fatalf("Expected driver name to be devicemapper got %s", d.String())
+	}
+}
+
+func TestDriverCreate(t *testing.T) {
+	denyAllDevmapper()
+	denyAllSyscall()
+	defer denyAllSyscall()
+	defer denyAllDevmapper()
+
+	calls := make(Set)
+	mockAllDevmapper(calls)
+
+	sysMount = func(source, target, fstype string, flags uintptr, data string) (err error) {
+		calls["sysMount"] = true
+		// FIXME: compare the exact source and target strings (inodes + devname)
+		if expectedSource := "/dev/mapper/docker-"; !strings.HasPrefix(source, expectedSource) {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedSource, source)
+		}
+		if expectedTarget := "/tmp/docker-test-devmapper-"; !strings.HasPrefix(target, expectedTarget) {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedTarget, target)
+		}
+		if expectedFstype := "ext4"; fstype != expectedFstype {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedFstype, fstype)
+		}
+		if expectedFlags := uintptr(3236757504); flags != expectedFlags {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedFlags, flags)
+		}
+		return nil
+	}
+
+	Mounted = func(mnt string) (bool, error) {
+		calls["Mounted"] = true
+		if !strings.HasPrefix(mnt, "/tmp/docker-test-devmapper-") || !strings.HasSuffix(mnt, "/mnt/1") {
+			t.Fatalf("Wrong mounted call\nExpected: Mounted(%v)\nReceived: Mounted(%v)\n", "/tmp/docker-test-devmapper-.../mnt/1", mnt)
+		}
+		return false, nil
+	}
+
+	sysSyscall = func(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
+		calls["sysSyscall"] = true
+		if trap != sysSysIoctl {
+			t.Fatalf("Unexpected syscall. Expecting SYS_IOCTL, received: %d", trap)
+		}
+		switch a2 {
+		case LoopSetFd:
+			calls["ioctl.loopsetfd"] = true
+		case LoopCtlGetFree:
+			calls["ioctl.loopctlgetfree"] = true
+		case LoopGetStatus64:
+			calls["ioctl.loopgetstatus"] = true
+		case LoopSetStatus64:
+			calls["ioctl.loopsetstatus"] = true
+		case LoopClrFd:
+			calls["ioctl.loopclrfd"] = true
+		case LoopSetCapacity:
+			calls["ioctl.loopsetcapacity"] = true
+		case BlkGetSize64:
+			calls["ioctl.blkgetsize"] = true
+		default:
+			t.Fatalf("Unexpected IOCTL. Received %d", a2)
+		}
+		return 0, 0, 0
+	}
+
+	func() {
+		d := newDriver(t)
+
+		calls.Assert(t,
+			"DmSetDevDir",
+			"DmLogWithErrnoInit",
+			"DmTaskSetName",
+			"DmTaskRun",
+			"DmTaskGetInfo",
+			"execRun",
+			"DmTaskCreate",
+			"DmTaskSetTarget",
+			"DmTaskSetCookie",
+			"DmUdevWait",
+			"DmTaskSetSector",
+			"DmTaskSetMessage",
+			"DmTaskSetAddNode",
+			"sysSyscall",
+			"ioctl.blkgetsize",
+			"ioctl.loopsetfd",
+			"ioctl.loopsetstatus",
+			"?ioctl.loopctlgetfree",
+		)
+
+		if err := d.Create("1", ""); err != nil {
+			t.Fatal(err)
+		}
+		calls.Assert(t,
+			"DmTaskCreate",
+			"DmTaskGetInfo",
+			"sysMount",
+			"DmTaskRun",
+			"DmTaskSetTarget",
+			"DmTaskSetSector",
+			"DmTaskSetCookie",
+			"DmUdevWait",
+			"DmTaskSetName",
+			"DmTaskSetMessage",
+			"DmTaskSetAddNode",
+		)
+
+	}()
+
+	runtime.GC()
+
+	calls.Assert(t,
+		"DmTaskDestroy",
+	)
+}
+
+func TestDriverRemove(t *testing.T) {
+	denyAllDevmapper()
+	denyAllSyscall()
+	defer denyAllSyscall()
+	defer denyAllDevmapper()
+
+	calls := make(Set)
+	mockAllDevmapper(calls)
+
+	sysMount = func(source, target, fstype string, flags uintptr, data string) (err error) {
+		calls["sysMount"] = true
+		// FIXME: compare the exact source and target strings (inodes + devname)
+		if expectedSource := "/dev/mapper/docker-"; !strings.HasPrefix(source, expectedSource) {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedSource, source)
+		}
+		if expectedTarget := "/tmp/docker-test-devmapper-"; !strings.HasPrefix(target, expectedTarget) {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedTarget, target)
+		}
+		if expectedFstype := "ext4"; fstype != expectedFstype {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedFstype, fstype)
+		}
+		if expectedFlags := uintptr(3236757504); flags != expectedFlags {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedFlags, flags)
+		}
+		return nil
+	}
+	sysUnmount = func(target string, flags int) (err error) {
+		calls["sysUnmount"] = true
+		// FIXME: compare the exact source and target strings (inodes + devname)
+		if expectedTarget := "/tmp/docker-test-devmapper-"; !strings.HasPrefix(target, expectedTarget) {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedTarget, target)
+		}
+		if expectedFlags := 0; flags != expectedFlags {
+			t.Fatalf("Wrong syscall call\nExpected: Mount(%v)\nReceived: Mount(%v)\n", expectedFlags, flags)
+		}
+		return nil
+	}
+	Mounted = func(mnt string) (bool, error) {
+		calls["Mounted"] = true
+		return false, nil
+	}
+
+	sysSyscall = func(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
+		calls["sysSyscall"] = true
+		if trap != sysSysIoctl {
+			t.Fatalf("Unexpected syscall. Expecting SYS_IOCTL, received: %d", trap)
+		}
+		switch a2 {
+		case LoopSetFd:
+			calls["ioctl.loopsetfd"] = true
+		case LoopCtlGetFree:
+			calls["ioctl.loopctlgetfree"] = true
+		case LoopGetStatus64:
+			calls["ioctl.loopgetstatus"] = true
+		case LoopSetStatus64:
+			calls["ioctl.loopsetstatus"] = true
+		case LoopClrFd:
+			calls["ioctl.loopclrfd"] = true
+		case LoopSetCapacity:
+			calls["ioctl.loopsetcapacity"] = true
+		case BlkGetSize64:
+			calls["ioctl.blkgetsize"] = true
+		default:
+			t.Fatalf("Unexpected IOCTL. Received %d", a2)
+		}
+		return 0, 0, 0
+	}
+
+	func() {
+		d := newDriver(t)
+
+		calls.Assert(t,
+			"DmSetDevDir",
+			"DmLogWithErrnoInit",
+			"DmTaskSetName",
+			"DmTaskRun",
+			"DmTaskGetInfo",
+			"execRun",
+			"DmTaskCreate",
+			"DmTaskSetTarget",
+			"DmTaskSetCookie",
+			"DmUdevWait",
+			"DmTaskSetSector",
+			"DmTaskSetMessage",
+			"DmTaskSetAddNode",
+			"sysSyscall",
+			"ioctl.blkgetsize",
+			"ioctl.loopsetfd",
+			"ioctl.loopsetstatus",
+			"?ioctl.loopctlgetfree",
+		)
+
+		if err := d.Create("1", ""); err != nil {
+			t.Fatal(err)
+		}
+
+		calls.Assert(t,
+			"DmTaskCreate",
+			"DmTaskGetInfo",
+			"sysMount",
+			"DmTaskRun",
+			"DmTaskSetTarget",
+			"DmTaskSetSector",
+			"DmTaskSetCookie",
+			"DmUdevWait",
+			"DmTaskSetName",
+			"DmTaskSetMessage",
+			"DmTaskSetAddNode",
+		)
+
+		Mounted = func(mnt string) (bool, error) {
+			calls["Mounted"] = true
+			return true, nil
+		}
+
+		if err := d.Remove("1"); err != nil {
+			t.Fatal(err)
+		}
+
+		calls.Assert(t,
+			"DmTaskRun",
+			"DmTaskSetSector",
+			"DmTaskSetName",
+			"DmTaskSetMessage",
+			"DmTaskCreate",
+			"DmTaskGetInfo",
+			"DmTaskSetCookie",
+			"DmTaskSetTarget",
+			"DmTaskSetAddNode",
+			"DmUdevWait",
+			"sysUnmount",
+		)
+	}()
+	runtime.GC()
+
+	calls.Assert(t,
+		"DmTaskDestroy",
+	)
+}
+
+func TestCleanup(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	t.Skip("Unimplemented")
+	d := newDriver(t)
+	defer osRemoveAll(d.home)
+
+	mountPoints := make([]string, 2)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+	// Mount the id
+	p, err := d.Get("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mountPoints[0] = p
+
+	if err := d.Create("2", "1"); err != nil {
+		t.Fatal(err)
+	}
+
+	p, err = d.Get("2")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mountPoints[1] = p
+
+	// Ensure that all the mount points are currently mounted
+	for _, p := range mountPoints {
+		if mounted, err := Mounted(p); err != nil {
+			t.Fatal(err)
+		} else if !mounted {
+			t.Fatalf("Expected %s to be mounted", p)
+		}
+	}
+
+	// Ensure that devices are active
+	for _, p := range []string{"1", "2"} {
+		if !d.HasActivatedDevice(p) {
+			t.Fatalf("Expected %s to have an active device", p)
+		}
+	}
+
+	if err := d.Cleanup(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Ensure that all the mount points are no longer mounted
+	for _, p := range mountPoints {
+		if mounted, err := Mounted(p); err != nil {
+			t.Fatal(err)
+		} else if mounted {
+			t.Fatalf("Expected %s to not be mounted", p)
+		}
+	}
+
+	// Ensure that devices are no longer activated
+	for _, p := range []string{"1", "2"} {
+		if d.HasActivatedDevice(p) {
+			t.Fatalf("Expected %s not be an active device", p)
+		}
+	}
+}
+
+func TestNotMounted(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	t.Skip("Not implemented")
+	d := newDriver(t)
+	defer cleanup(d)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	mounted, err := Mounted(path.Join(d.home, "mnt", "1"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if mounted {
+		t.Fatal("Id 1 should not be mounted")
+	}
+}
+
+func TestMounted(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	d := newDriver(t)
+	defer cleanup(d)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := d.Get("1"); err != nil {
+		t.Fatal(err)
+	}
+
+	mounted, err := Mounted(path.Join(d.home, "mnt", "1"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !mounted {
+		t.Fatal("Id 1 should be mounted")
+	}
+}
+
+func TestInitCleanedDriver(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	d := newDriver(t)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := d.Get("1"); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := d.Cleanup(); err != nil {
+		t.Fatal(err)
+	}
+
+	driver, err := Init(d.home)
+	if err != nil {
+		t.Fatal(err)
+	}
+	d = driver.(*Driver)
+	defer cleanup(d)
+
+	if _, err := d.Get("1"); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestMountMountedDriver(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	d := newDriver(t)
+	defer cleanup(d)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	// Perform get on same id to ensure that it will
+	// not be mounted twice
+	if _, err := d.Get("1"); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := d.Get("1"); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestGetReturnsValidDevice(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	d := newDriver(t)
+	defer cleanup(d)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	if !d.HasDevice("1") {
+		t.Fatalf("Expected id 1 to be in device set")
+	}
+
+	if _, err := d.Get("1"); err != nil {
+		t.Fatal(err)
+	}
+
+	if !d.HasActivatedDevice("1") {
+		t.Fatalf("Expected id 1 to be activated")
+	}
+
+	if !d.HasInitializedDevice("1") {
+		t.Fatalf("Expected id 1 to be initialized")
+	}
+}
+
+func TestDriverGetSize(t *testing.T) {
+	t.Skip("FIXME: not a unit test")
+	t.Skipf("Size is currently not implemented")
+
+	d := newDriver(t)
+	defer cleanup(d)
+
+	if err := d.Create("1", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	mountPoint, err := d.Get("1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	size := int64(1024)
+
+	f, err := osCreate(path.Join(mountPoint, "test_file"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Truncate(size); err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	// diffSize, err := d.DiffSize("1")
+	// if err != nil {
+	// 	t.Fatal(err)
+	// }
+	// if diffSize != size {
+	// 	t.Fatalf("Expected size %d got %d", size, diffSize)
+	// }
+}
+
+func assertMap(t *testing.T, m map[string]bool, keys ...string) {
+	for _, key := range keys {
+		if _, exists := m[key]; !exists {
+			t.Fatalf("Key not set: %s", key)
+		}
+		delete(m, key)
+	}
+	if len(m) != 0 {
+		t.Fatalf("Unexpected keys: %v", m)
+	}
+}

runtime/graphdriver/devmapper/ioctl.go

@@ -0,0 +1,71 @@
+// +build linux,amd64
+
+package devmapper
+
+import (
+	"unsafe"
+)
+
+func ioctlLoopCtlGetFree(fd uintptr) (int, error) {
+	index, _, err := sysSyscall(sysSysIoctl, fd, LoopCtlGetFree, 0)
+	if err != 0 {
+		return 0, err
+	}
+	return int(index), nil
+}
+
+func ioctlLoopSetFd(loopFd, sparseFd uintptr) error {
+	if _, _, err := sysSyscall(sysSysIoctl, loopFd, LoopSetFd, sparseFd); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func ioctlLoopSetStatus64(loopFd uintptr, loopInfo *LoopInfo64) error {
+	if _, _, err := sysSyscall(sysSysIoctl, loopFd, LoopSetStatus64, uintptr(unsafe.Pointer(loopInfo))); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func ioctlLoopClrFd(loopFd uintptr) error {
+	if _, _, err := sysSyscall(sysSysIoctl, loopFd, LoopClrFd, 0); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func ioctlLoopGetStatus64(loopFd uintptr) (*LoopInfo64, error) {
+	loopInfo := &LoopInfo64{}
+
+	if _, _, err := sysSyscall(sysSysIoctl, loopFd, LoopGetStatus64, uintptr(unsafe.Pointer(loopInfo))); err != 0 {
+		return nil, err
+	}
+	return loopInfo, nil
+}
+
+func ioctlLoopSetCapacity(loopFd uintptr, value int) error {
+	if _, _, err := sysSyscall(sysSysIoctl, loopFd, LoopSetCapacity, uintptr(value)); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func ioctlBlkGetSize64(fd uintptr) (int64, error) {
+	var size int64
+	if _, _, err := sysSyscall(sysSysIoctl, fd, BlkGetSize64, uintptr(unsafe.Pointer(&size))); err != 0 {
+		return 0, err
+	}
+	return size, nil
+}
+
+func ioctlBlkDiscard(fd uintptr, offset, length uint64) error {
+	var r [2]uint64
+	r[0] = offset
+	r[1] = length
+
+	if _, _, err := sysSyscall(sysSysIoctl, fd, BlkDiscard, uintptr(unsafe.Pointer(&r[0]))); err != 0 {
+		return err
+	}
+	return nil
+}

runtime/graphdriver/devmapper/mount.go

@@ -0,0 +1,27 @@
+// +build linux,amd64
+
+package devmapper
+
+import (
+	"path/filepath"
+)
+
+// FIXME: this is copy-pasted from the aufs driver.
+// It should be moved into the core.
+
+var Mounted = func(mountpoint string) (bool, error) {
+	mntpoint, err := osStat(mountpoint)
+	if err != nil {
+		if osIsNotExist(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	parent, err := osStat(filepath.Join(mountpoint, ".."))
+	if err != nil {
+		return false, err
+	}
+	mntpointSt := toSysStatT(mntpoint.Sys())
+	parentSt := toSysStatT(parent.Sys())
+	return mntpointSt.Dev != parentSt.Dev, nil
+}

runtime/graphdriver/devmapper/sys.go

@@ -0,0 +1,57 @@
+// +build linux,amd64
+
+package devmapper
+
+import (
+	"os"
+	"os/exec"
+	"syscall"
+)
+
+type (
+	sysStatT syscall.Stat_t
+	sysErrno syscall.Errno
+
+	osFile struct{ *os.File }
+)
+
+var (
+	sysMount       = syscall.Mount
+	sysUnmount     = syscall.Unmount
+	sysCloseOnExec = syscall.CloseOnExec
+	sysSyscall     = syscall.Syscall
+
+	osOpenFile = func(name string, flag int, perm os.FileMode) (*osFile, error) {
+		f, err := os.OpenFile(name, flag, perm)
+		return &osFile{File: f}, err
+	}
+	osOpen       = func(name string) (*osFile, error) { f, err := os.Open(name); return &osFile{File: f}, err }
+	osNewFile    = os.NewFile
+	osCreate     = os.Create
+	osStat       = os.Stat
+	osIsNotExist = os.IsNotExist
+	osIsExist    = os.IsExist
+	osMkdirAll   = os.MkdirAll
+	osRemoveAll  = os.RemoveAll
+	osRename     = os.Rename
+	osReadlink   = os.Readlink
+
+	execRun = func(name string, args ...string) error { return exec.Command(name, args...).Run() }
+)
+
+const (
+	sysMsMgcVal = syscall.MS_MGC_VAL
+	sysMsRdOnly = syscall.MS_RDONLY
+	sysEInval   = syscall.EINVAL
+	sysSysIoctl = syscall.SYS_IOCTL
+	sysEBusy    = syscall.EBUSY
+
+	osORdOnly    = os.O_RDONLY
+	osORdWr      = os.O_RDWR
+	osOCreate    = os.O_CREATE
+	osModeDevice = os.ModeDevice
+)
+
+func toSysStatT(i interface{}) *sysStatT {
+	return (*sysStatT)(i.(*syscall.Stat_t))
+}

runtime/graphdriver/driver.go

@@ -0,0 +1,93 @@
+package graphdriver
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/archive"
+	"github.com/dotcloud/docker/utils"
+	"os"
+	"path"
+)
+
+type InitFunc func(root string) (Driver, error)
+
+type Driver interface {
+	String() string
+
+	Create(id, parent string) error
+	Remove(id string) error
+
+	Get(id string) (dir string, err error)
+	Put(id string)
+	Exists(id string) bool
+
+	Status() [][2]string
+
+	Cleanup() error
+}
+
+type Differ interface {
+	Diff(id string) (archive.Archive, error)
+	Changes(id string) ([]archive.Change, error)
+	ApplyDiff(id string, diff archive.ArchiveReader) error
+	DiffSize(id string) (bytes int64, err error)
+}
+
+var (
+	DefaultDriver string
+	// All registred drivers
+	drivers map[string]InitFunc
+	// Slice of drivers that should be used in an order
+	priority = []string{
+		"aufs",
+		"devicemapper",
+		"vfs",
+		// experimental, has to be enabled manually for now
+		"btrfs",
+	}
+)
+
+func init() {
+	drivers = make(map[string]InitFunc)
+}
+
+func Register(name string, initFunc InitFunc) error {
+	if _, exists := drivers[name]; exists {
+		return fmt.Errorf("Name already registered %s", name)
+	}
+	drivers[name] = initFunc
+
+	return nil
+}
+
+func GetDriver(name, home string) (Driver, error) {
+	if initFunc, exists := drivers[name]; exists {
+		return initFunc(path.Join(home, name))
+	}
+	return nil, fmt.Errorf("No such driver: %s", name)
+}
+
+func New(root string) (driver Driver, err error) {
+	for _, name := range []string{os.Getenv("DOCKER_DRIVER"), DefaultDriver} {
+		if name != "" {
+			return GetDriver(name, root)
+		}
+	}
+
+	// Check for priority drivers first
+	for _, name := range priority {
+		if driver, err = GetDriver(name, root); err != nil {
+			utils.Debugf("Error loading driver %s: %s", name, err)
+			continue
+		}
+		return driver, nil
+	}
+
+	// Check all registered drivers if no priority driver is found
+	for _, initFunc := range drivers {
+		if driver, err = initFunc(root); err != nil {
+			continue
+		}
+		return driver, nil
+	}
+	return nil, err
+}

runtime/graphdriver/vfs/driver.go

@@ -0,0 +1,95 @@
+package vfs
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/runtime/graphdriver"
+	"os"
+	"os/exec"
+	"path"
+)
+
+func init() {
+	graphdriver.Register("vfs", Init)
+}
+
+func Init(home string) (graphdriver.Driver, error) {
+	d := &Driver{
+		home: home,
+	}
+	return d, nil
+}
+
+type Driver struct {
+	home string
+}
+
+func (d *Driver) String() string {
+	return "vfs"
+}
+
+func (d *Driver) Status() [][2]string {
+	return nil
+}
+
+func (d *Driver) Cleanup() error {
+	return nil
+}
+
+func copyDir(src, dst string) error {
+	if output, err := exec.Command("cp", "-aT", "--reflink=auto", src, dst).CombinedOutput(); err != nil {
+		return fmt.Errorf("Error VFS copying directory: %s (%s)", err, output)
+	}
+	return nil
+}
+
+func (d *Driver) Create(id string, parent string) error {
+	dir := d.dir(id)
+	if err := os.MkdirAll(path.Dir(dir), 0700); err != nil {
+		return err
+	}
+	if err := os.Mkdir(dir, 0700); err != nil {
+		return err
+	}
+	if parent == "" {
+		return nil
+	}
+	parentDir, err := d.Get(parent)
+	if err != nil {
+		return fmt.Errorf("%s: %s", parent, err)
+	}
+	if err := copyDir(parentDir, dir); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (d *Driver) dir(id string) string {
+	return path.Join(d.home, "dir", path.Base(id))
+}
+
+func (d *Driver) Remove(id string) error {
+	if _, err := os.Stat(d.dir(id)); err != nil {
+		return err
+	}
+	return os.RemoveAll(d.dir(id))
+}
+
+func (d *Driver) Get(id string) (string, error) {
+	dir := d.dir(id)
+	if st, err := os.Stat(dir); err != nil {
+		return "", err
+	} else if !st.IsDir() {
+		return "", fmt.Errorf("%s: not a directory", dir)
+	}
+	return dir, nil
+}
+
+func (d *Driver) Put(id string) {
+	// The vfs driver has no runtime resources (e.g. mounts)
+	// to clean up, so we don't need anything here
+}
+
+func (d *Driver) Exists(id string) bool {
+	_, err := os.Stat(d.dir(id))
+	return err == nil
+}

runtime/runtime.go

@@ -11,11 +11,11 @@ import (
 	"github.com/dotcloud/docker/runtime/execdriver/execdrivers"
 	"github.com/dotcloud/docker/runtime/execdriver/lxc"
 	"github.com/dotcloud/docker/graph"
-	"github.com/dotcloud/docker/graphdriver"
-	"github.com/dotcloud/docker/graphdriver/aufs"
-	_ "github.com/dotcloud/docker/graphdriver/btrfs"
-	_ "github.com/dotcloud/docker/graphdriver/devmapper"
-	_ "github.com/dotcloud/docker/graphdriver/vfs"
+	"github.com/dotcloud/docker/runtime/graphdriver"
+	"github.com/dotcloud/docker/runtime/graphdriver/aufs"
+	_ "github.com/dotcloud/docker/runtime/graphdriver/btrfs"
+	_ "github.com/dotcloud/docker/runtime/graphdriver/devmapper"
+	_ "github.com/dotcloud/docker/runtime/graphdriver/vfs"
 	"github.com/dotcloud/docker/image"
 	_ "github.com/dotcloud/docker/runtime/networkdriver/lxc"
 	"github.com/dotcloud/docker/runtime/networkdriver/portallocator"