xfs_read_icluster
error = xfs_read_icluster(pag, tp, imap.im_agbno, &bp);
int xfs_read_icluster(struct xfs_perag *pag, struct xfs_trans *tp,
error = xfs_read_icluster(pag, bs->cur->bc_tp, imap.im_agbno,
error = xfs_read_icluster(sc->sa.pag, sc->tp, cluster_bno,
error = xfs_read_icluster(pag, tp, ip->i_imap.im_agbno, &bp);
error = xfs_read_icluster(pag, tp, ip->i_imap.im_agbno, &bp);
error = xfs_read_icluster(iup->pag, tp, ip->i_imap.im_agbno, &ibp);