@@ -34,9 +34,6 @@ func getCheckpointDir(checkDir, checkpointID, ctrName, ctrID, ctrCheckpointDir s

 			err2 = fmt.Errorf("checkpoint with name %s already exists for container %s", checkpointID, ctrName)

 		case err != nil && os.IsNotExist(err):

 			err2 = os.MkdirAll(checkpointAbsDir, 0700)

-			if os.IsExist(err2) {

-				err2 = nil

-			}

 		case err != nil:

 			err2 = err

 		case err == nil:

@@ -675,14 +675,14 @@ func NewDaemon(config *config.Config, registryService registry.Service, containe

 	}

 	daemonRepo := filepath.Join(config.Root, "containers")

-	if err := idtools.MkdirAllAndChown(daemonRepo, 0700, rootIDs); err != nil && !os.IsExist(err) {

+	if err := idtools.MkdirAllAndChown(daemonRepo, 0700, rootIDs); err != nil {

 		return nil, err

 	}

 	// Create the directory where we'll store the runtime scripts (i.e. in

 	// order to support runtimeArgs)

 	daemonRuntimes := filepath.Join(config.Root, "runtimes")

-	if err := system.MkdirAll(daemonRuntimes, 0700, ""); err != nil && !os.IsExist(err) {

+	if err := system.MkdirAll(daemonRuntimes, 0700, ""); err != nil {

 		return nil, err

 	}

 	if err := d.loadRuntimes(); err != nil {

@@ -690,7 +690,7 @@ func NewDaemon(config *config.Config, registryService registry.Service, containe

 	}

 	if runtime.GOOS == "windows" {

-		if err := system.MkdirAll(filepath.Join(config.Root, "credentialspecs"), 0, ""); err != nil && !os.IsExist(err) {

+		if err := system.MkdirAll(filepath.Join(config.Root, "credentialspecs"), 0, ""); err != nil {

 			return nil, err

 		}

 	}

@@ -1514,7 +1514,7 @@ func (daemon *Daemon) initCgroupsPath(path string) error {

 func maybeCreateCPURealTimeFile(sysinfoPresent bool, configValue int64, file string, path string) error {

 	if sysinfoPresent && configValue != 0 {

-		if err := os.MkdirAll(path, 0755); err != nil && !os.IsExist(err) {

+		if err := os.MkdirAll(path, 0755); err != nil {

 			return err

 		}

 		if err := ioutil.WriteFile(filepath.Join(path, file), []byte(strconv.FormatInt(configValue, 10)), 0700); err != nil {

@@ -3,7 +3,6 @@ package daemon

 import (

 	"context"

 	"fmt"

-	"os"

 	"path/filepath"

 	"strings"

@@ -485,7 +484,7 @@ func setupRemappedRoot(config *config.Config) (*idtools.IDMappings, error) {

 func setupDaemonRoot(config *config.Config, rootDir string, rootIDs idtools.IDPair) error {

 	config.Root = rootDir

 	// Create the root directory if it doesn't exists

-	if err := system.MkdirAllWithACL(config.Root, 0, system.SddlAdministratorsLocalSystem); err != nil && !os.IsExist(err) {

+	if err := system.MkdirAllWithACL(config.Root, 0, system.SddlAdministratorsLocalSystem); err != nil {

 		return err

 	}

 	return nil

@@ -122,13 +122,8 @@ func Init(root string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap

 	if err != nil {

 		return nil, err

 	}

-	// Create the root aufs driver dir and return

-	// if it already exists

-	// If not populate the dir structure

+	// Create the root aufs driver dir

 	if err := idtools.MkdirAllAndChown(root, 0700, idtools.IDPair{UID: rootUID, GID: rootGID}); err != nil {

-		if os.IsExist(err) {

-			return a, nil

-		}

 		return nil, err

 	}

@@ -268,7 +268,7 @@ func (devices *DeviceSet) ensureImage(name string, size int64) (string, error) {

 	if err != nil {

 		return "", err

 	}

-	if err := idtools.MkdirAllAndChown(dirname, 0700, idtools.IDPair{UID: uid, GID: gid}); err != nil && !os.IsExist(err) {

+	if err := idtools.MkdirAllAndChown(dirname, 0700, idtools.IDPair{UID: uid, GID: gid}); err != nil {

 		return "", err

 	}

@@ -1697,10 +1697,10 @@ func (devices *DeviceSet) initDevmapper(doInit bool) (retErr error) {

 	if err != nil {

 		return err

 	}

-	if err := idtools.MkdirAndChown(devices.root, 0700, idtools.IDPair{UID: uid, GID: gid}); err != nil && !os.IsExist(err) {

+	if err := idtools.MkdirAndChown(devices.root, 0700, idtools.IDPair{UID: uid, GID: gid}); err != nil {

 		return err

 	}

-	if err := os.MkdirAll(devices.metadataDir(), 0700); err != nil && !os.IsExist(err) {

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

 		return err

 	}

@@ -189,7 +189,7 @@ func (d *Driver) Get(id, mountLabel string) (containerfs.ContainerFS, error) {

 	}

 	// Create the target directories if they don't exist

-	if err := idtools.MkdirAllAndChown(path.Join(d.home, "mnt"), 0755, idtools.IDPair{UID: uid, GID: gid}); err != nil && !os.IsExist(err) {

+	if err := idtools.MkdirAllAndChown(path.Join(d.home, "mnt"), 0755, idtools.IDPair{UID: uid, GID: gid}); err != nil {

 		d.ctr.Decrement(mp)

 		return nil, err

 	}

@@ -204,7 +204,7 @@ func (d *Driver) Get(id, mountLabel string) (containerfs.ContainerFS, error) {

 		return nil, err

 	}

-	if err := idtools.MkdirAllAndChown(rootFs, 0755, idtools.IDPair{UID: uid, GID: gid}); err != nil && !os.IsExist(err) {

+	if err := idtools.MkdirAllAndChown(rootFs, 0755, idtools.IDPair{UID: uid, GID: gid}); err != nil {

 		d.ctr.Decrement(mp)

 		d.DeviceSet.UnmountDevice(id, mp)

 		return nil, err

@@ -138,7 +138,7 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap

 		return nil, err

 	}

 	// Create the driver home dir

-	if err := idtools.MkdirAllAndChown(home, 0700, idtools.IDPair{rootUID, rootGID}); err != nil && !os.IsExist(err) {

+	if err := idtools.MkdirAllAndChown(home, 0700, idtools.IDPair{rootUID, rootGID}); err != nil {

 		return nil, err

 	}

@@ -177,7 +177,7 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap

 		return nil, err

 	}

 	// Create the driver home dir

-	if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0700, idtools.IDPair{rootUID, rootGID}); err != nil && !os.IsExist(err) {

+	if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0700, idtools.IDPair{rootUID, rootGID}); err != nil {

 		return nil, err

 	}

@@ -42,7 +42,9 @@ func MkdirAllAndChown(path string, mode os.FileMode, owner IDPair) error {

 }

 // MkdirAndChown creates a directory and then modifies ownership to the requested uid/gid.

-// If the directory already exists, this function still changes ownership

+// If the directory already exists, this function still changes ownership.

+// Note that unlike os.Mkdir(), this function does not return IsExist error

+// in case path already exists.

 func MkdirAndChown(path string, mode os.FileMode, owner IDPair) error {

 	return mkdirAs(path, mode, owner.UID, owner.GID, false, true)

 }

@@ -10,6 +10,7 @@ import (

 	"path/filepath"

 	"strings"

 	"sync"

+	"syscall"

 	"github.com/docker/docker/pkg/system"

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

@@ -29,6 +30,9 @@ func mkdirAs(path string, mode os.FileMode, ownerUID, ownerGID int, mkAll, chown

 	stat, err := system.Stat(path)

 	if err == nil {

+		if !stat.IsDir() {

+			return &os.PathError{Op: "mkdir", Path: path, Err: syscall.ENOTDIR}

+		}

 		if !chownExisting {

 			return nil

 		}

@@ -54,7 +58,7 @@ func mkdirAs(path string, mode os.FileMode, ownerUID, ownerGID int, mkAll, chown

 				paths = append(paths, dirPath)

 			}

 		}

-		if err := system.MkdirAll(path, mode, ""); err != nil && !os.IsExist(err) {

+		if err := system.MkdirAll(path, mode, ""); err != nil {

 			return err

 		}

 	} else {

@@ -378,6 +378,20 @@ func TestLookupUserAndGroupThatDoesNotExist(t *testing.T) {

 	assert.Error(t, err)

 }

+// TestMkdirIsNotDir checks that mkdirAs() function (used by MkdirAll...)

+// returns a correct error in case a directory which it is about to create

+// already exists but is a file (rather than a directory).

+func TestMkdirIsNotDir(t *testing.T) {

+	file, err := ioutil.TempFile("", t.Name())

+	if err != nil {

+		t.Fatalf("Couldn't create temp dir: %v", err)

+	}

+	defer os.Remove(file.Name())

+

+	err = mkdirAs(file.Name(), 0755, 0, 0, false, false)

+	assert.EqualError(t, err, "mkdir "+file.Name()+": not a directory")

+}

+

 func RequiresRoot(t *testing.T) {

 	skip.IfCondition(t, os.Getuid() != 0, "skipping test that requires root")

 }

@@ -11,7 +11,7 @@ import (

 // Platforms such as Windows do not support the UID/GID concept. So make this

 // just a wrapper around system.MkdirAll.

 func mkdirAs(path string, mode os.FileMode, ownerUID, ownerGID int, mkAll, chownExisting bool) error {

-	if err := system.MkdirAll(path, mode, ""); err != nil && !os.IsExist(err) {

+	if err := system.MkdirAll(path, mode, ""); err != nil {

 		return err

 	}

 	return nil

@@ -47,6 +47,11 @@ func (s StatT) Mtim() syscall.Timespec {

 	return s.mtim

 }

+// IsDir reports whether s describes a directory.

+func (s StatT) IsDir() bool {

+	return s.mode&syscall.S_IFDIR != 0

+}

+

 // Stat takes a path to a file and returns

 // a system.StatT type pertaining to that file.

 //

@@ -139,16 +139,6 @@ func (r *Root) Name() string {

 	return volume.DefaultDriverName

 }

-type alreadyExistsError struct {

-	path string

-}

-

-func (e alreadyExistsError) Error() string {

-	return "local volume already exists under " + e.path

-}

-

-func (e alreadyExistsError) Conflict() {}

-

 type systemError struct {

 	err error

 }

@@ -181,9 +171,6 @@ func (r *Root) Create(name string, opts map[string]string) (volume.Volume, error

 	path := r.DataPath(name)

 	if err := idtools.MkdirAllAndChown(path, 0755, r.rootIDs); err != nil {

-		if os.IsExist(err) {

-			return nil, alreadyExistsError{filepath.Dir(path)}

-		}

 		return nil, errors.Wrapf(systemError{err}, "error while creating volume path '%s'", path)

 	}

@@ -192,7 +192,6 @@ func (m *MountPoint) Setup(mountLabel string, rootIDs idtools.IDPair, checkFun f

 		return "", fmt.Errorf("Unable to setup mount point, neither source nor volume defined")

 	}

-	// system.MkdirAll() produces an error if m.Source exists and is a file (not a directory),

 	if m.Type == mounttypes.TypeBind {

 		// Before creating the source directory on the host, invoke checkFun if it's not nil. One of

 		// the use case is to forbid creating the daemon socket as a directory if the daemon is in