Fuse: Passthrough options to allow other-users access and mounting in empty directory. (#691)

cli/command_mount.go

@@ -21,6 +21,9 @@ var (
 	mountPoint       = mountCommand.Arg("mountPoint", "Mount point").Default("*").String()
 	mountPointBrowse = mountCommand.Flag("browse", "Open file browser").Bool()
 	mountTraceFS     = mountCommand.Flag("trace-fs", "Trace filesystem operations").Bool()
+
+	mountFuseAllowOther         = mountCommand.Flag("fuse-allow-other", "Allows other users to access the file system.").Bool()
+	mountFuseAllowNonEmptyMount = mountCommand.Flag("fuse-allow-non-empty-mount", "Allows the mounting over a non-empty directory. The files in it will be shadowed by the freshly created mount.").Bool()
 )
 
 func runMountCommand(ctx context.Context, rep repo.Repository) error {
@@ -42,7 +45,11 @@ func runMountCommand(ctx context.Context, rep repo.Repository) error {
 
 	entry = cachefs.Wrap(entry, newFSCache()).(fs.Directory)
 
-	ctrl, mountErr := mount.Directory(ctx, entry, *mountPoint)
+	ctrl, mountErr := mount.Directory(ctx, entry, *mountPoint,
+		mount.Options{
+			FuseAllowOther:         *mountFuseAllowOther,
+			FuseAllowNonEmptyMount: *mountFuseAllowNonEmptyMount,
+		})
 
 	if mountErr != nil {
 		return errors.Wrap(mountErr, "mount error")
@@ -68,15 +75,27 @@ func runMountCommand(ctx context.Context, rep repo.Repository) error {
 	onCtrlC(func() {
 		close(ctrlCPressed)
 	})
+
 	select {
 	case <-ctrlCPressed:
 		log(ctx).Infof("Unmounting...")
-		return ctrl.Unmount(ctx)
+		// TODO: Consider lazy unmounting (-z) and polling till the filesystem is unmounted instead of failing with:
+		// "unmount error: exit status 1: fusermount: failed to unmount /tmp/kopia-mount719819963: Device or resource busy, try --help"
+		err := ctrl.Unmount(ctx)
+		if err != nil {
+			return err
+		}
 
 	case <-ctrl.Done():
 		log(ctx).Infof("Unmounted.")
 		return nil
 	}
+
+	// Reporting clean unmount in case of interrupt signal.
+	<-ctrl.Done()
+	log(ctx).Infof("Unmounted.")
+
+	return nil
 }
 
 func init() {

go.mod

@@ -54,4 +54,5 @@ require (
 	google.golang.org/protobuf v1.25.0
 	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 	gopkg.in/kothar/go-backblaze.v0 v0.0.0-20191215213626-7594ed38700f
+	mvdan.cc/gofumpt v0.0.0-20200927160801-5bfeb2e70dd6 // indirect
 )

go.sum

@@ -597,6 +597,7 @@ github.com/rjeczalik/notify v0.9.2 h1:MiTWrPj55mNDHEiIX5YUSKefw/+lCQVoAFmD6oQm5w
 github.com/rjeczalik/notify v0.9.2/go.mod h1:aErll2f0sUX9PXZnVNyeiObbmTlk5jnMoCa4QEjJeqM=
 github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af/go.mod h1:XWv6SoW27p1b0cqNHllgS5HIMJraePCO15w5zCzIWYg=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
+github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
 github.com/rs/cors v1.7.0 h1:+88SsELBHx5r+hZ8TCkggzSstaWNbDvThkVK8H6f9ik=
 github.com/rs/cors v1.7.0/go.mod h1:gFx+x8UowdsKA9AchylcLynDq+nNFfI8FkUZdN/jGCU=
 github.com/rs/xid v1.2.1/go.mod h1:+uKXf+4Djp6Md1KODXJxgGQPKngRmWyn10oCKFzNHOQ=
@@ -944,6 +945,7 @@ golang.org/x/tools v0.0.0-20200606014950-c42cb6316fb6/go.mod h1:EkVYQZoAsY45+roY
 golang.org/x/tools v0.0.0-20200608174601-1b747fd94509/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
 golang.org/x/tools v0.0.0-20200618134242-20370b0cb4b2/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
 golang.org/x/tools v0.0.0-20200729194436-6467de6f59a7/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
+golang.org/x/tools v0.0.0-20200731060945-b5fad4ed8dd6/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20200804011535-6c149bb5ef0d/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20200814172026-c4923e618c08/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20200825202427-b303f430e36d/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
@@ -1127,6 +1129,8 @@ honnef.co/go/tools v0.0.1-2020.1.3 h1:sXmLre5bzIR6ypkjXCDI3jHPssRhc8KD/Ome589sc3
 honnef.co/go/tools v0.0.1-2020.1.3/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9vFzvIQ3k=
 honnef.co/go/tools v0.0.1-2020.1.4 h1:UoveltGrhghAA7ePc+e+QYDHXrBps2PqFZiHkGR/xK8=
 honnef.co/go/tools v0.0.1-2020.1.4/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9vFzvIQ3k=
+mvdan.cc/gofumpt v0.0.0-20200927160801-5bfeb2e70dd6 h1:z+/YqapuV7VZPvBb3GYmuEJbA88M3PFUxaHilHYVCpQ=
+mvdan.cc/gofumpt v0.0.0-20200927160801-5bfeb2e70dd6/go.mod h1:bzrjFmaD6+xqohD3KYP0H2FEuxknnBmyyOxdhLdaIws=
 rsc.io/binaryregexp v0.2.0/go.mod h1:qTv7/COck+e2FymRvadv62gMdZztPaShugOCi3I+8D8=
 rsc.io/pdf v0.1.1/go.mod h1:n8OzWcQ6Sp37PL01nO98y4iUCRdTGarVfzxY20ICaU4=
 rsc.io/quote/v3 v3.1.0/go.mod h1:yEA65RcK8LyAZtP9Kv3t0HmxON59tX3rD+tICJqUlj0=

internal/mount/mount.go

@@ -15,3 +15,12 @@ type Controller interface {
 	MountPath() string
 	Done() <-chan struct{}
 }
+
+// Options cary set of flags passed to the mount layer.
+type Options struct {
+	// AllowOther allows other users to access the file system. Supported on FUSE"
+	FuseAllowOther bool
+	// Allows the mounting over a non-empty directory. The files in it will be shadowed by the freshly created mount.
+	// Supported only on Fuse.
+	FuseAllowNonEmptyMount bool
+}

internal/mount/mount_fuse.go

@@ -23,8 +23,27 @@ func (r *root) Root() (fusefs.Node, error) {
 	return r.Node, nil
 }
 
+func (mo *Options) toFuseMountOptions() []fuse.MountOption {
+	options := []fuse.MountOption{
+		fuse.ReadOnly(),
+		fuse.FSName("kopia"),
+		fuse.Subtype("kopia"),
+		fuse.VolumeName("Kopia"),
+	}
+
+	if mo.FuseAllowOther {
+		options = append(options, fuse.AllowOther())
+	}
+
+	if mo.FuseAllowNonEmptyMount {
+		options = append(options, fuse.AllowNonEmptyMount())
+	}
+
+	return options
+}
+
 // Directory mounts the given directory using FUSE.
-func Directory(ctx context.Context, entry fs.Directory, mountPoint string) (Controller, error) {
+func Directory(ctx context.Context, entry fs.Directory, mountPoint string, mountOptions Options) (Controller, error) {
 	isTempDir := false
 
 	if mountPoint == "*" {
@@ -40,13 +59,14 @@ func Directory(ctx context.Context, entry fs.Directory, mountPoint string) (Cont
 
 	rootNode := fusemount.NewDirectoryNode(entry)
 
-	fuseConnection, err := fuse.Mount(
-		mountPoint,
+	options := append(
+		mountOptions.toFuseMountOptions(),
 		fuse.ReadOnly(),
 		fuse.FSName("kopia"),
 		fuse.Subtype("kopia"),
-		fuse.VolumeName("Kopia"),
-	)
+		fuse.VolumeName("Kopia"))
+
+	fuseConnection, err := fuse.Mount(mountPoint, options...)
 	if err != nil {
 		return nil, errors.Wrap(err, "error creating fuse connection")
 	}

internal/mount/mount_net_use.go

@@ -14,7 +14,7 @@ import (
 )
 
 // Directory mounts a given directory under a provided drive letter.
-func Directory(ctx context.Context, entry fs.Directory, driveLetter string) (Controller, error) {
+func Directory(ctx context.Context, entry fs.Directory, driveLetter string, _ Options) (Controller, error) {
 	if !isValidWindowsDriveOrAsterisk(driveLetter) {
 		return nil, errors.Errorf("must be a valid drive letter or asteris")
 	}

internal/server/api_mount.go

@@ -31,7 +31,7 @@ func (s *Server) handleMountCreate(ctx context.Context, r *http.Request, body []
 		log(ctx).Debugf("mount controller for %v not found, starting", oid)
 
 		var err error
-		c, err = mount.Directory(ctx, snapshotfs.DirectoryEntry(s.rep, oid, nil), "*")
+		c, err = mount.Directory(ctx, snapshotfs.DirectoryEntry(s.rep, oid, nil), "*", mount.Options{})
 
 		if err != nil {
 			return nil, internalServerError(err)