xfs_bmap_compute_maxlevels(
	xfs_mount_t	*mp,		/* file system mount structure */
	int		whichfork)	/* data or attr fork */
{
	int		level;		/* btree level */
	uint		maxblocks;	/* max blocks at this level */
	uint		maxleafents;	/* max leaf entries possible */
	int		maxrootrecs;	/* max records in root block */
	int		minleafrecs;	/* min records in leaf block */
	int		minnoderecs;	/* min records in node block */
	int		sz;		/* root block size */

	/*
	 * The maximum number of extents in a file, hence the maximum
	 * number of leaf entries, is controlled by the type of di_nextents
	 * (a signed 32-bit number, xfs_extnum_t), or by di_anextents
	 * (a signed 16-bit number, xfs_aextnum_t).
	 *
	 * Note that we can no longer assume that if we are in ATTR1 that
	 * the fork offset of all the inodes will be
	 * (xfs_default_attroffset(ip) >> 3) because we could have mounted
	 * with ATTR2 and then mounted back with ATTR1, keeping the
	 * di_forkoff's fixed but probably at various positions. Therefore,
	 * for both ATTR1 and ATTR2 we have to assume the worst case scenario
	 * of a minimum size available.
	 */
	if (whichfork == XFS_DATA_FORK) {
		maxleafents = MAXEXTNUM;
		sz = XFS_BMDR_SPACE_CALC(MINDBTPTRS);
	} else {
		maxleafents = MAXAEXTNUM;
		sz = XFS_BMDR_SPACE_CALC(MINABTPTRS);
	}
	maxrootrecs = xfs_bmdr_maxrecs(sz, 0);
	minleafrecs = mp->m_bmap_dmnr[0];
	minnoderecs = mp->m_bmap_dmnr[1];
	maxblocks = (maxleafents + minleafrecs - 1) / minleafrecs;
	for (level = 1; maxblocks > 1; level++) {
		if (maxblocks <= maxrootrecs)
			maxblocks = 1;
		else
			maxblocks = (maxblocks + minnoderecs - 1) / minnoderecs;
	}
	mp->m_bm_maxlevels[whichfork] = level;
}
xfs_bmap_compute_maxlevels(
	xfs_mount_t	*mp,		 
	int		whichfork)	 
{
	int		level;		 
	uint		maxblocks;	 
	uint		maxleafents;	 
	int		maxrootrecs;	 
	int		minleafrecs;	 
	int		minnoderecs;	 
	int		sz;		 

	 
	if (whichfork == XFS_DATA_FORK) {
		maxleafents = MAXEXTNUM;
		sz = XFS_BMDR_SPACE_CALC(MINDBTPTRS);
	} else {
		maxleafents = MAXAEXTNUM;
		sz = XFS_BMDR_SPACE_CALC(MINABTPTRS);
	}
	maxrootrecs = xfs_bmdr_maxrecs(sz, 0);
	minleafrecs = mp->m_bmap_dmnr[0];
	minnoderecs = mp->m_bmap_dmnr[1];
	maxblocks = (maxleafents + minleafrecs - 1) / minleafrecs;
	for (level = 1; maxblocks > 1; level++) {
		if (maxblocks <= maxrootrecs)
			maxblocks = 1;
		else
			maxblocks = (maxblocks + minnoderecs - 1) / minnoderecs;
	}
	mp->m_bm_maxlevels[whichfork] = level;
}