xfs_compute_rextslog
*rsumlevels = xfs_compute_rextslog(rextents) + 1;
sbp->sb_rextslog != xfs_compute_rextslog(sbp->sb_rextents) ||
uint8_t xfs_compute_rextslog(xfs_rtbxlen_t rtextents);
rtb->rextslog = xfs_compute_rextslog(rtb->rextents);
nmp->m_sb.sb_rextslog = xfs_compute_rextslog(nmp->m_sb.sb_rextents);