virtiofsd: passthrough_ll: control readdirplus

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

tools/virtiofsd/helper.c

@@ -153,6 +153,10 @@ void fuse_cmdline_help(void)
            "                               allowed (default: 10)\n"
            "    -o norace                  disable racy fallback\n"
            "                               default: false\n"
+           "    -o readdirplus|no_readdirplus\n"
+           "                               enable/disable readirplus\n"
+           "                               default: readdirplus except with "
+           "cache=never\n"
           );
 }