VFS_MOUNT
error = VFS_MOUNT(mp, "/dev", NULL, cred);
error = VFS_MOUNT(mp, NULL, NULL, proc0.p_ucred);
if ((error = VFS_MOUNT(synth_mp, NULL, NULL, proc0.p_ucred))) {
error = VFS_MOUNT(mp, uap->path, uap->data, cred);
error = VFS_MOUNT(mp, uap->path, uap->data, cred);