mount: add --devname to set the device name sent to FUSE for mount display

Before this change, the device name was always the remote:path rclone
was configured with. However this can contain sensitive information
and it appears in the `mount` output, so `--devname` allows the user
to configure it.

See: https://forum.rclone.org/t/rclone-mount-blomp-problem/29151/11

cmd/mount2/mount.go

@@ -25,11 +25,10 @@ func init() {
 // mountOptions configures the options from the command line flags
 //
 // man mount.fuse for more info and note the -o flag for other options
-func mountOptions(fsys *FS, f fs.Fs) (mountOpts *fuse.MountOptions) {
-	device := f.Name() + ":" + f.Root()
+func mountOptions(fsys *FS, f fs.Fs, opt *mountlib.Options) (mountOpts *fuse.MountOptions) {
 	mountOpts = &fuse.MountOptions{
 		AllowOther:    fsys.opt.AllowOther,
-		FsName:        device,
+		FsName:        opt.DeviceName,
 		Name:          "rclone",
 		DisableXAttrs: true,
 		Debug:         fsys.opt.DebugFUSE,
@@ -120,7 +119,7 @@ func mountOptions(fsys *FS, f fs.Fs) (mountOpts *fuse.MountOptions) {
 	if runtime.GOOS == "darwin" {
 		opts = append(opts,
 			// VolumeName sets the volume name shown in Finder.
-			fmt.Sprintf("volname=%s", device),
+			fmt.Sprintf("volname=%s", opt.VolumeName),
 
 			// NoAppleXattr makes OSXFUSE disallow extended attributes with the
 			// prefix "com.apple.". This disables persistent Finder state and
@@ -167,7 +166,7 @@ func mount(VFS *vfs.VFS, mountpoint string, opt *mountlib.Options) (<-chan error
 	//mOpts.Debug = mountlib.DebugFUSE
 
 	//conn := fusefs.NewFileSystemConnector(nodeFs.Root(), mOpts)
-	mountOpts := mountOptions(fsys, f)
+	mountOpts := mountOptions(fsys, f, opt)
 
 	// FIXME fill out
 	opts := fusefs.Options{