Commit 0ed5f735 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: compute absolute maximum nlevels for each btree type 



Add code for all five btree types so that we can compute the absolute
maximum possible btree height for each btree type.  This is a setup for
the next patch, which makes every btree type have its own cursor cache.

The functions are exported so that we can have xfs_db report the
absolute maximum btree heights for each btree type, rather than making
everyone run their own ad-hoc computations.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
parent bc8883eb

fs/xfs/libxfs/xfs_alloc.c

+1 −0
Original line number Diff line number Diff line
@@ -2198,6 +2198,7 @@ xfs_alloc_compute_maxlevels( 
{

	mp->m_alloc_maxlevels = xfs_btree_compute_maxlevels(mp->m_alloc_mnr,

			(mp->m_sb.sb_agblocks + 1) / 2);

	ASSERT(mp->m_alloc_maxlevels <= xfs_allocbt_maxlevels_ondisk());

}



/*

fs/xfs/libxfs/xfs_alloc_btree.c

+30 −3
Original line number Diff line number Diff line
@@ -566,6 +566,17 @@ xfs_allocbt_commit_staged_btree( 
	}

}



/* Calculate number of records in an alloc btree block. */

static inline unsigned int

xfs_allocbt_block_maxrecs(

	unsigned int		blocklen,

	bool			leaf)

{

	if (leaf)

		return blocklen / sizeof(xfs_alloc_rec_t);

	return blocklen / (sizeof(xfs_alloc_key_t) + sizeof(xfs_alloc_ptr_t));

}



/*

 * Calculate number of records in an alloc btree block.

 */
@@ -576,10 +587,26 @@ xfs_allocbt_maxrecs( 
	int			leaf)

{

	blocklen -= XFS_ALLOC_BLOCK_LEN(mp);

	return xfs_allocbt_block_maxrecs(blocklen, leaf);

}



	if (leaf)

		return blocklen / sizeof(xfs_alloc_rec_t);

	return blocklen / (sizeof(xfs_alloc_key_t) + sizeof(xfs_alloc_ptr_t));

/* Free space btrees are at their largest when every other block is free. */

#define XFS_MAX_FREESP_RECORDS	((XFS_MAX_AG_BLOCKS + 1) / 2)



/* Compute the max possible height for free space btrees. */

unsigned int

xfs_allocbt_maxlevels_ondisk(void)

{

	unsigned int		minrecs[2];

	unsigned int		blocklen;



	blocklen = min(XFS_MIN_BLOCKSIZE - XFS_BTREE_SBLOCK_LEN,

		       XFS_MIN_CRC_BLOCKSIZE - XFS_BTREE_SBLOCK_CRC_LEN);



	minrecs[0] = xfs_allocbt_block_maxrecs(blocklen, true) / 2;

	minrecs[1] = xfs_allocbt_block_maxrecs(blocklen, false) / 2;



	return xfs_btree_compute_maxlevels(minrecs, XFS_MAX_FREESP_RECORDS);

}



/* Calculate the freespace btree size for some records. */

fs/xfs/libxfs/xfs_alloc_btree.h

+2 −0
Original line number Diff line number Diff line
@@ -60,4 +60,6 @@ extern xfs_extlen_t xfs_allocbt_calc_size(struct xfs_mount *mp, 
void xfs_allocbt_commit_staged_btree(struct xfs_btree_cur *cur,

		struct xfs_trans *tp, struct xfs_buf *agbp);



unsigned int xfs_allocbt_maxlevels_ondisk(void);



#endif	/* __XFS_ALLOC_BTREE_H__ */

fs/xfs/libxfs/xfs_bmap.c

+1 −0
Original line number Diff line number Diff line
@@ -93,6 +93,7 @@ xfs_bmap_compute_maxlevels( 
			maxblocks = (maxblocks + minnoderecs - 1) / minnoderecs;

	}

	mp->m_bm_maxlevels[whichfork] = level;

	ASSERT(mp->m_bm_maxlevels[whichfork] <= xfs_bmbt_maxlevels_ondisk());

}



unsigned int

fs/xfs/libxfs/xfs_bmap_btree.c

+28 −3
Original line number Diff line number Diff line
@@ -571,6 +571,17 @@ xfs_bmbt_init_cursor( 
	return cur;

}



/* Calculate number of records in a block mapping btree block. */

static inline unsigned int

xfs_bmbt_block_maxrecs(

	unsigned int		blocklen,

	bool			leaf)

{

	if (leaf)

		return blocklen / sizeof(xfs_bmbt_rec_t);

	return blocklen / (sizeof(xfs_bmbt_key_t) + sizeof(xfs_bmbt_ptr_t));

}



/*

 * Calculate number of records in a bmap btree block.

 */
@@ -581,10 +592,24 @@ xfs_bmbt_maxrecs( 
	int			leaf)

{

	blocklen -= XFS_BMBT_BLOCK_LEN(mp);

	return xfs_bmbt_block_maxrecs(blocklen, leaf);

}



	if (leaf)

		return blocklen / sizeof(xfs_bmbt_rec_t);

	return blocklen / (sizeof(xfs_bmbt_key_t) + sizeof(xfs_bmbt_ptr_t));

/* Compute the max possible height for block mapping btrees. */

unsigned int

xfs_bmbt_maxlevels_ondisk(void)

{

	unsigned int		minrecs[2];

	unsigned int		blocklen;



	blocklen = min(XFS_MIN_BLOCKSIZE - XFS_BTREE_SBLOCK_LEN,

		       XFS_MIN_CRC_BLOCKSIZE - XFS_BTREE_SBLOCK_CRC_LEN);



	minrecs[0] = xfs_bmbt_block_maxrecs(blocklen, true) / 2;

	minrecs[1] = xfs_bmbt_block_maxrecs(blocklen, false) / 2;



	/* One extra level for the inode root. */

	return xfs_btree_compute_maxlevels(minrecs, MAXEXTNUM) + 1;

}



/*