@@ -9,16 +9,20 @@ type minfo struct {

 // RefCounter is a generic counter for use by graphdriver Get/Put calls

 type RefCounter struct {

-	counts  map[string]*minfo

-	mu      sync.Mutex

-	checker Checker

+	counts    map[string]*minfo

+	mu        sync.Mutex

+	isMounted Checker

 }

-// NewRefCounter returns a new RefCounter

+// Checker checks whether the provided path is mounted.

+type Checker func(path string) bool

+

+// NewRefCounter returns a new RefCounter. It accepts a [Checker] to

+// determine whether a path is mounted.

 func NewRefCounter(c Checker) *RefCounter {

 	return &RefCounter{

-		checker: c,

-		counts:  make(map[string]*minfo),

+		isMounted: c,

+		counts:    make(map[string]*minfo),

 	}

 }

@@ -48,7 +52,7 @@ func (c *RefCounter) incdec(path string, infoOp func(minfo *minfo)) int {

 	// count if it is mounted as it is in use.

 	if !m.check {

 		m.check = true

-		if c.checker.IsMounted(path) {

+		if c.isMounted(path) {

 			m.count++

 		}

 	}

@@ -128,12 +128,6 @@ type FileGetCloser interface {

 	Close() error

 }

-// Checker makes checks on specified filesystems.

-type Checker interface {

-	// IsMounted returns true if the provided path is mounted for the specific checker

-	IsMounted(path string) bool

-}

-

 func init() {

 	drivers = make(map[string]InitFunc)

 }

@@ -1,38 +1,4 @@

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

-import (

-	"github.com/docker/docker/daemon/internal/fstype"

-	"github.com/moby/sys/mountinfo"

-)

-

 // List of drivers that should be used in an order

 var priority = "overlay2,fuse-overlayfs,btrfs,zfs,vfs"

-

-// NewFsChecker returns a checker configured for the provided FsMagic

-func NewFsChecker(t fstype.FsMagic) Checker {

-	return &fsChecker{

-		t: t,

-	}

-}

-

-type fsChecker struct {

-	t fstype.FsMagic

-}

-

-func (c *fsChecker) IsMounted(path string) bool {

-	fsType, _ := fstype.GetFSMagic(path)

-	return fsType == c.t

-}

-

-// NewDefaultChecker returns a check that parses /proc/mountinfo to check

-// if the specified path is mounted.

-func NewDefaultChecker() Checker {

-	return &defaultChecker{}

-}

-

-type defaultChecker struct{}

-

-func (c *defaultChecker) IsMounted(path string) bool {

-	m, _ := mountinfo.Mounted(path)

-	return m

-}

@@ -98,7 +98,7 @@ func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdr

 	d := &Driver{

 		home:   home,

 		idMap:  idMap,

-		ctr:    graphdriver.NewRefCounter(graphdriver.NewFsChecker(fstype.FsMagicFUSE)),

+		ctr:    graphdriver.NewRefCounter(isMounted),

 		locker: locker.New(),

 	}

@@ -107,6 +107,12 @@ func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdr

 	return d, nil

 }

+// isMounted checks whether the given path is a [fstype.FsMagicFUSE] mount.

+func isMounted(path string) bool {

+	fsType, _ := fstype.GetFSMagic(path)

+	return fsType == fstype.FsMagicFUSE

+}

+

 func (d *Driver) String() string {

 	return driverName

 }

@@ -179,7 +179,7 @@ func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdr

 	d := &Driver{

 		home:          home,

 		idMap:         idMap,

-		ctr:           graphdriver.NewRefCounter(graphdriver.NewFsChecker(fstype.FsMagicOverlay)),

+		ctr:           graphdriver.NewRefCounter(isMounted),

 		supportsDType: supportsDType,

 		usingMetacopy: usingMetacopy,

 		locker:        locker.New(),

@@ -225,6 +225,12 @@ func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdr

 	return d, nil

 }

+// isMounted checks whether the given path is a [fstype.FsMagicOverlay] mount.

+func isMounted(path string) bool {

+	fsType, _ := fstype.GetFSMagic(path)

+	return fsType == fstype.FsMagicOverlay

+}

+

 func parseOptions(options []string) (*overlayOptions, error) {

 	o := &overlayOptions{}

 	for _, option := range options {

@@ -72,12 +72,6 @@ func init() {

 	}

 }

-type checker struct{}

-

-func (c *checker) IsMounted(path string) bool {

-	return false

-}

-

 type storageOptions struct {

 	size uint64

 }

@@ -132,12 +126,18 @@ func InitFilter(home string, options []string, _ idtools.IdentityMapping) (graph

 			Flavour: filterDriver,

 		},

 		cache:              make(map[string]string),

-		ctr:                graphdriver.NewRefCounter(&checker{}),

+		ctr:                graphdriver.NewRefCounter(isMounted),

 		defaultStorageOpts: opts,

 	}

 	return d, nil

 }

+// isMounted checks whether the given path is mounted. It always returns

+// false for the WindowsFilter graphdriver.

+func isMounted(string) bool {

+	return false

+}

+

 // String returns the string representation of a driver. This should match

 // the name the graph driver has been registered with.

 func (d *Driver) String() string {

@@ -118,12 +118,19 @@ func Init(base string, opt []string, idMap idtools.IdentityMapping) (graphdriver

 		options:          options,

 		filesystemsCache: filesystemsCache,

 		idMap:            idMap,

-		ctr:              graphdriver.NewRefCounter(graphdriver.NewDefaultChecker()),

+		ctr:              graphdriver.NewRefCounter(isMounted),

 		locker:           locker.New(),

 	}

 	return graphdriver.NewNaiveDiffDriver(d, idMap), nil

 }

+// isMounted parses /proc/mountinfo to check whether the specified path

+// is mounted.

+func isMounted(path string) bool {

+	m, _ := mountinfo.Mounted(path)

+	return m

+}

+

 func parseOptions(opt []string) (zfsOptions, error) {

 	var options zfsOptions

 	options.fsName = ""

@@ -32,7 +32,7 @@ func NewMounter(home string, snapshotter string, idMap idtools.IdentityMapping)

 			snapshotter: snapshotter,

 			idMap:       idMap,

 		},

-		rc:     graphdriver.NewRefCounter(checker()),

+		rc:     graphdriver.NewRefCounter(isMounted),

 		locker: locker.New(),

 	}

 }

deleted file mode 100644

@@ -1,17 +0,0 @@

-//go:build !windows

-

-package snapshotter

-

-import (

-	"github.com/containerd/containerd/mount"

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

-	"golang.org/x/sys/unix"

-)

-

-func checker() graphdriver.Checker {

-	return graphdriver.NewDefaultChecker()

-}

-

-func unmount(target string) error {

-	return mount.Unmount(target, unix.MNT_DETACH)

-}

new file mode 100644

@@ -0,0 +1,20 @@

+//go:build !windows

+

+package snapshotter

+

+import (

+	"github.com/containerd/containerd/mount"

+	"github.com/moby/sys/mountinfo"

+	"golang.org/x/sys/unix"

+)

+

+// isMounted parses /proc/mountinfo to check whether the specified path

+// is mounted.

+func isMounted(path string) bool {

+	m, _ := mountinfo.Mounted(path)

+	return m

+}

+

+func unmount(target string) error {

+	return mount.Unmount(target, unix.MNT_DETACH)

+}

@@ -2,15 +2,7 @@ package snapshotter

 import "github.com/containerd/containerd/mount"

-type winChecker struct{}

-

-func (c *winChecker) IsMounted(path string) bool {

-	return false

-}

-

-func checker() *winChecker {

-	return &winChecker{}

-}

+func isMounted(string) bool { return false }

 func unmount(target string) error {

 	return mount.Unmount(target, 0)