g_slice_new
gp = g_slice_new(mp, FLASH_SLICES_MAX_NUM, pp, &cp, (void**)&gfp,
struct g_geom * g_slice_new(struct g_class *mp, u_int slices, struct g_provider *pp, struct g_consumer **cpp, void *extrap, int extra, g_slice_start_t *start);
gp = g_slice_new(mp, 1, pp, &cp, NULL, 0, NULL);