num_maps = (blocks + BLOCKS_PER_MAP - 1) /
(unsigned long long) BLOCKS_PER_MAP;
f->file_map = smalloc(num_maps * sizeof(long));
num_maps = (blocks + BLOCKS_PER_MAP - 1) /
(unsigned long long) BLOCKS_PER_MAP;
f->file_map = smalloc(num_maps * sizeof(long));