cluster_read
error = cluster_read(vp, ip->i_size,
error = cluster_read(vp, (off_t)ip->i_size,
error = cluster_read(devvp, io->offset + limit,
error = cluster_read(vp, (off_t)ip->i_size,
error = cluster_read(vp, (off_t)ip->i_size,
error = cluster_read(vp, (off_t)ip->i_size,