daemon/graphdriver: move RefCounter to an internal package

The RefCounter is used in both graphdrivers and snapshotters. Move it
to a separate package to help decoupling snapshotters and graphdrivers,
and make it internal, as it's not intended to be used as a generic utility
package (we can still make it public if there would be a need).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/graphdriver/fuse-overlayfs/fuseoverlayfs.go

@@ -18,6 +18,7 @@ import (
 	"github.com/docker/docker/daemon/graphdriver"
 	"github.com/docker/docker/daemon/graphdriver/overlayutils"
 	"github.com/docker/docker/daemon/internal/fstype"
+	"github.com/docker/docker/daemon/internal/mountref"
 	"github.com/docker/docker/internal/containerfs"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/chrootarchive"
@@ -59,7 +60,7 @@ const (
 type Driver struct {
 	home      string
 	idMap     idtools.IdentityMapping
-	ctr       *graphdriver.RefCounter
+	ctr       *mountref.Counter
 	naiveDiff graphdriver.DiffDriver
 	locker    *locker.Locker
 }
@@ -98,7 +99,7 @@ func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdr
 	d := &Driver{
 		home:   home,
 		idMap:  idMap,
-		ctr:    graphdriver.NewRefCounter(isMounted),
+		ctr:    mountref.NewCounter(isMounted),
 		locker: locker.New(),
 	}
 

daemon/graphdriver/overlay2/overlay.go

@@ -20,6 +20,7 @@ import (
 	"github.com/docker/docker/daemon/graphdriver"
 	"github.com/docker/docker/daemon/graphdriver/overlayutils"
 	"github.com/docker/docker/daemon/internal/fstype"
+	"github.com/docker/docker/daemon/internal/mountref"
 	"github.com/docker/docker/internal/containerfs"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/chrootarchive"
@@ -93,7 +94,7 @@ type overlayOptions struct {
 type Driver struct {
 	home          string
 	idMap         idtools.IdentityMapping
-	ctr           *graphdriver.RefCounter
+	ctr           *mountref.Counter
 	quotaCtl      *quota.Control
 	options       overlayOptions
 	naiveDiff     graphdriver.DiffDriver
@@ -179,7 +180,7 @@ func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdr
 	d := &Driver{
 		home:          home,
 		idMap:         idMap,
-		ctr:           graphdriver.NewRefCounter(isMounted),
+		ctr:           mountref.NewCounter(isMounted),
 		supportsDType: supportsDType,
 		usingMetacopy: usingMetacopy,
 		locker:        locker.New(),

daemon/graphdriver/windows/windows.go

@@ -26,6 +26,7 @@ import (
 	"github.com/Microsoft/hcsshim/osversion"
 	"github.com/containerd/log"
 	"github.com/docker/docker/daemon/graphdriver"
+	"github.com/docker/docker/daemon/internal/mountref"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/idtools"
 	"github.com/docker/docker/pkg/ioutils"
@@ -80,7 +81,7 @@ type storageOptions struct {
 type Driver struct {
 	// info stores the shim driver information
 	info hcsshim.DriverInfo
-	ctr  *graphdriver.RefCounter
+	ctr  *mountref.Counter
 	// it is safe for windows to use a cache here because it does not support
 	// restoring containers when the daemon dies.
 	cacheMu            sync.Mutex
@@ -126,7 +127,7 @@ func InitFilter(home string, options []string, _ idtools.IdentityMapping) (graph
 			Flavour: filterDriver,
 		},
 		cache:              make(map[string]string),
-		ctr:                graphdriver.NewRefCounter(isMounted),
+		ctr:                mountref.NewCounter(isMounted),
 		defaultStorageOpts: opts,
 	}
 	return d, nil

daemon/graphdriver/zfs/zfs.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/containerd/log"
 	"github.com/docker/docker/daemon/graphdriver"
+	"github.com/docker/docker/daemon/internal/mountref"
 	"github.com/docker/docker/pkg/idtools"
 	"github.com/docker/docker/pkg/parsers"
 	zfs "github.com/mistifyio/go-zfs/v3"
@@ -118,7 +119,7 @@ func Init(base string, opt []string, idMap idtools.IdentityMapping) (graphdriver
 		options:          options,
 		filesystemsCache: filesystemsCache,
 		idMap:            idMap,
-		ctr:              graphdriver.NewRefCounter(isMounted),
+		ctr:              mountref.NewCounter(isMounted),
 		locker:           locker.New(),
 	}
 	return graphdriver.NewNaiveDiffDriver(d, idMap), nil
@@ -182,7 +183,7 @@ type Driver struct {
 	sync.Mutex       // protects filesystem cache against concurrent access
 	filesystemsCache map[string]bool
 	idMap            idtools.IdentityMapping
-	ctr              *graphdriver.RefCounter
+	ctr              *mountref.Counter
 	locker           *locker.Locker
 }
 

daemon/internal/mountref/counter.go

@@ -1,4 +1,4 @@
-package graphdriver // import "github.com/docker/docker/daemon/graphdriver"
+package mountref
 
 import "sync"
 
@@ -7,8 +7,8 @@ type minfo struct {
 	count int
 }
 
-// RefCounter is a generic counter for use by graphdriver Get/Put calls
-type RefCounter struct {
+// Counter is a generic counter for use by graphdriver Get/Put calls
+type Counter struct {
 	counts    map[string]*minfo
 	mu        sync.Mutex
 	isMounted Checker
@@ -17,30 +17,30 @@ type RefCounter struct {
 // Checker checks whether the provided path is mounted.
 type Checker func(path string) bool
 
-// NewRefCounter returns a new RefCounter. It accepts a [Checker] to
+// NewCounter returns a new Counter. It accepts a [Checker] to
 // determine whether a path is mounted.
-func NewRefCounter(c Checker) *RefCounter {
-	return &RefCounter{
+func NewCounter(c Checker) *Counter {
+	return &Counter{
 		isMounted: c,
 		counts:    make(map[string]*minfo),
 	}
 }
 
 // Increment increases the ref count for the given id and returns the current count
-func (c *RefCounter) Increment(path string) int {
+func (c *Counter) Increment(path string) int {
 	return c.incdec(path, func(minfo *minfo) {
 		minfo.count++
 	})
 }
 
 // Decrement decreases the ref count for the given id and returns the current count
-func (c *RefCounter) Decrement(path string) int {
+func (c *Counter) Decrement(path string) int {
 	return c.incdec(path, func(minfo *minfo) {
 		minfo.count--
 	})
 }
 
-func (c *RefCounter) incdec(path string, infoOp func(minfo *minfo)) int {
+func (c *Counter) incdec(path string, infoOp func(minfo *minfo)) int {
 	c.mu.Lock()
 	m := c.counts[path]
 	if m == nil {

daemon/snapshotter/mount.go

@@ -7,7 +7,7 @@ import (
 
 	"github.com/containerd/containerd/mount"
 	"github.com/containerd/log"
-	"github.com/docker/docker/daemon/graphdriver"
+	"github.com/docker/docker/daemon/internal/mountref"
 	"github.com/docker/docker/pkg/idtools"
 	"github.com/moby/locker"
 	"github.com/moby/sys/mountinfo"
@@ -32,13 +32,13 @@ func NewMounter(home string, snapshotter string, idMap idtools.IdentityMapping)
 			snapshotter: snapshotter,
 			idMap:       idMap,
 		},
-		rc:     graphdriver.NewRefCounter(isMounted),
+		rc:     mountref.NewCounter(isMounted),
 		locker: locker.New(),
 	}
 }
 
 type refCountMounter struct {
-	rc     *graphdriver.RefCounter
+	rc     *mountref.Counter
 	locker *locker.Locker
 	base   mounter
 }