mountlib: fix VFS instance leaks on mount failures and unmounts

cmd/cmount/mount.go

@@ -170,8 +170,6 @@ func mount(VFS *vfs.VFS, mountPath string, opt *mountlib.Options) (<-chan error,
 
 	// unmount
 	unmount := func() error {
-		// Shutdown the VFS
-		fsys.VFS.Shutdown()
 		var umountOK bool
 		if fsys.destroyed.Load() != 0 {
 			fs.Debugf(nil, "Not calling host.Unmount as mount already Destroyed")

cmd/mount/mount.go

@@ -103,8 +103,6 @@ func mount(VFS *vfs.VFS, mountpoint string, opt *mountlib.Options) (<-chan error
 	}()
 
 	unmount := func() error {
-		// Shutdown the VFS
-		filesys.VFS.Shutdown()
 		return fuse.Unmount(mountpoint)
 	}
 

cmd/mount2/mount.go

@@ -241,8 +241,6 @@ func mount(VFS *vfs.VFS, mountpoint string, opt *mountlib.Options) (<-chan error
 	// }
 
 	umount := func() error {
-		// Shutdown the VFS
-		fsys.VFS.Shutdown()
 		return server.Unmount()
 	}
 

cmd/mountlib/mount.go

@@ -210,16 +210,26 @@ type (
 
 // MountPoint represents a mount with options and runtime state
 type MountPoint struct {
-	Ctx        context.Context
-	MountPoint string
-	MountedOn  time.Time
-	MountOpt   Options
-	VFSOpt     vfscommon.Options
-	Fs         fs.Fs
-	VFS        *vfs.VFS
-	MountFn    MountFn
-	UnmountFn  UnmountFn
-	ErrChan    <-chan error
+	Ctx             context.Context
+	MountPoint      string
+	MountedOn       time.Time
+	MountOpt        Options
+	VFSOpt          vfscommon.Options
+	Fs              fs.Fs
+	VFS             *vfs.VFS
+	MountFn         MountFn
+	UnmountFn       UnmountFn
+	ErrChan         <-chan error
+	vfsShutdownOnce sync.Once
+}
+
+// shutdownVFS shuts down the VFS instance exactly once
+func (m *MountPoint) shutdownVFS() {
+	m.vfsShutdownOnce.Do(func() {
+		if m.VFS != nil {
+			m.VFS.Shutdown()
+		}
+	})
 }
 
 // NewMountPoint makes a new mounting structure
@@ -386,6 +396,7 @@ func (m *MountPoint) Mount() (mountDaemon *os.Process, err error) {
 	var actualMountpoint string
 	m.ErrChan, m.UnmountFn, actualMountpoint, err = m.MountFn(m.VFS, m.MountPoint, &m.MountOpt)
 	if err != nil {
+		m.shutdownVFS()
 		if len(os.Args) > 0 && strings.HasPrefix(os.Args[0], "/snap/") {
 			return nil, fmt.Errorf("mounting is not supported when running from snap")
 		}
@@ -404,6 +415,7 @@ func (m *MountPoint) Wait() error {
 	var finaliseOnce sync.Once
 	finalise := func() {
 		finaliseOnce.Do(func() {
+			defer m.shutdownVFS()
 			// Unmount only if directory was mounted by rclone, e.g. don't unmount autofs hooks.
 			if err := CheckMountReady(m.MountPoint); err != nil {
 				fs.Debugf(m.MountPoint, "Unmounted externally. Just exit now.")
@@ -431,5 +443,9 @@ func (m *MountPoint) Wait() error {
 
 // Unmount the specified mountpoint
 func (m *MountPoint) Unmount() (err error) {
-	return m.UnmountFn()
+	defer m.shutdownVFS()
+	if m.UnmountFn != nil {
+		return m.UnmountFn()
+	}
+	return nil
 }

cmd/nfsmount/nfsmount.go

@@ -117,7 +117,6 @@ func mount(VFS *vfs.VFS, mountpoint string, opt *mountlib.Options) (asyncerrors
 			out, umountErr = exec.Command(cmd[0], cmd[1:]...).CombinedOutput()
 		}
 		shutdownErr := s.Shutdown()
-		VFS.Shutdown()
 		if umountErr != nil {
 			out = bytes.TrimSpace(out)
 			return fmt.Errorf("%s: failed to umount the NFS volume %e", out, umountErr)
@@ -130,7 +129,6 @@ func mount(VFS *vfs.VFS, mountpoint string, opt *mountlib.Options) (asyncerrors
 	nfs.OnUnmountFunc = func() {
 		s.UnmountedExternally = true
 		errChan <- nil
-		VFS.Shutdown()
 	}
 
 	actualMountpoint = mountpoint