[PATCH 2/5] libxfs: refactor the btree size calculator code

["Darrick J. Wong" <darrick.wong@xxxxxxxxxx>]

Create a macro to generate btree height calculator functions.
This will be used (much) later when we get to the refcount
btree.

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 libxfs/xfs_bmap.c       |   18 +-----------------
 libxfs/xfs_bmap_btree.c |    9 +++++++++
 libxfs/xfs_bmap_btree.h |    3 +++
 libxfs/xfs_btree.c      |   28 ++++++++++++++++++++++++++++
 libxfs/xfs_btree.h      |    3 +++
 5 files changed, 44 insertions(+), 17 deletions(-)


diff --git a/libxfs/xfs_bmap.c b/libxfs/xfs_bmap.c
index aef7cf3..c134765 100644
--- a/libxfs/xfs_bmap.c
+++ b/libxfs/xfs_bmap.c
@@ -172,25 +172,9 @@ xfs_bmap_worst_indlen(
 	xfs_inode_t	*ip,		/* incore inode pointer */
 	xfs_filblks_t	len)		/* delayed extent length */
 {
-	int		level;		/* btree level number */
-	int		maxrecs;	/* maximum record count at this level */
-	xfs_mount_t	*mp;		/* mount structure */
 	xfs_filblks_t	rval;		/* return value */
 
-	mp = ip->i_mount;
-	maxrecs = mp->m_bmap_dmxr[0];
-	for (level = 0, rval = 0;
-	     level < XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK);
-	     level++) {
-		len += maxrecs - 1;
-		do_div(len, maxrecs);
-		rval += len;
-		if (len == 1)
-			return rval + XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK) -
-				level - 1;
-		if (level == 0)
-			maxrecs = mp->m_bmap_dmxr[1];
-	}
+	rval = xfs_bmbt_calc_size(ip->i_mount, len);
 	return rval;
 }
 
diff --git a/libxfs/xfs_bmap_btree.c b/libxfs/xfs_bmap_btree.c
index 2ef1836..3c595e2 100644
--- a/libxfs/xfs_bmap_btree.c
+++ b/libxfs/xfs_bmap_btree.c
@@ -880,3 +880,12 @@ xfs_bmbt_change_owner(
 	xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
 	return error;
 }
+
+xfs_filblks_t
+xfs_bmbt_calc_size(
+	struct xfs_mount	*mp,
+	unsigned long		len)
+{
+	return xfs_btree_calc_size(mp, mp->m_bmap_dmxr,
+			XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK), len);
+}
diff --git a/libxfs/xfs_bmap_btree.h b/libxfs/xfs_bmap_btree.h
index 819a8a4..04bc6e2 100644
--- a/libxfs/xfs_bmap_btree.h
+++ b/libxfs/xfs_bmap_btree.h
@@ -140,4 +140,7 @@ extern int xfs_bmbt_change_owner(struct xfs_trans *tp, struct xfs_inode *ip,
 extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,
 		struct xfs_trans *, struct xfs_inode *, int);
 
+extern xfs_filblks_t xfs_bmbt_calc_size(struct xfs_mount *mp,
+		unsigned long len);
+
 #endif	/* __XFS_BMAP_BTREE_H__ */
diff --git a/libxfs/xfs_btree.c b/libxfs/xfs_btree.c
index 658f27e..d5f16c5 100644
--- a/libxfs/xfs_btree.c
+++ b/libxfs/xfs_btree.c
@@ -4081,6 +4081,34 @@ xfs_btree_change_owner(
 	return 0;
 }
 
+/*
+ * xfs_btree_calc_size() -- Calculate the number of blocks needed to store
+ *			    a given number of records.
+ */
+xfs_filblks_t
+xfs_btree_calc_size(
+	struct xfs_mount	*mp,
+	uint			*limits,
+	int			maxlevels,
+	unsigned long		len)
+{
+	int			level;
+	int			maxrecs;
+	xfs_filblks_t		rval;
+
+	maxrecs = limits[0];
+	for (level = 0, rval = 0; level < maxlevels; level++) {
+		len += maxrecs - 1;
+		do_div(len, maxrecs);
+		rval += len;
+		if (len == 1)
+			return rval + maxlevels - level - 1;
+		if (level == 0)
+			maxrecs = limits[1];
+	}
+	return rval;
+}
+
 /**
  * xfs_btree_sblock_v5hdr_verify() -- verify the v5 fields of a short-format
  *				      btree block
diff --git a/libxfs/xfs_btree.h b/libxfs/xfs_btree.h
index 48cb251..b25ffd3 100644
--- a/libxfs/xfs_btree.h
+++ b/libxfs/xfs_btree.h
@@ -465,6 +465,9 @@ static inline int xfs_btree_get_level(struct xfs_btree_block *block)
 #define XFS_BTREE_TRACE_ARGR(c, r)
 #define	XFS_BTREE_TRACE_CURSOR(c, t)
 
+xfs_filblks_t xfs_btree_calc_size(struct xfs_mount *mp, uint *limits,
+		int maxlevels, unsigned long len);
+
 bool xfs_btree_sblock_v5hdr_verify(struct xfs_buf *bp);
 bool xfs_btree_sblock_verify(struct xfs_buf *bp, unsigned int max_recs);
 

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