From 4ed3f68792f6a9c21a290ae777565e7562a09653 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Mon, 19 Sep 2016 10:25:03 +1000
Subject: [PATCH] xfs: create a standard btree size calculator code
Create a helper to generate AG 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@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
---
fs/xfs/libxfs/xfs_btree.c | 24 ++++++++++++++++++++++++
fs/xfs/libxfs/xfs_btree.h | 2 ++
2 files changed, 26 insertions(+)
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 7be8d9cda2b69..50cfb98719dd5 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -4797,3 +4797,27 @@ xfs_btree_query_range(
return xfs_btree_overlapped_query_range(cur, &low_key, &high_key,
fn, priv);
}
+
+/*
+ * Calculate the number of blocks needed to store a given number of records
+ * in a short-format (per-AG metadata) btree.
+ */
+xfs_extlen_t
+xfs_btree_calc_size(
+ struct xfs_mount *mp,
+ uint *limits,
+ unsigned long long len)
+{
+ int level;
+ int maxrecs;
+ xfs_extlen_t rval;
+
+ maxrecs = limits[0];
+ for (level = 0, rval = 0; len > 1; level++) {
+ len += maxrecs - 1;
+ do_div(len, maxrecs);
+ maxrecs = limits[1];
+ rval += len;
+ }
+ return rval;
+}
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index f41a4cfff740e..1c148f5c5675a 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -501,6 +501,8 @@ bool xfs_btree_sblock_v5hdr_verify(struct xfs_buf *bp);
bool xfs_btree_sblock_verify(struct xfs_buf *bp, unsigned int max_recs);
uint xfs_btree_compute_maxlevels(struct xfs_mount *mp, uint *limits,
unsigned long len);
+xfs_extlen_t xfs_btree_calc_size(struct xfs_mount *mp, uint *limits,
+ unsigned long long len);
/* return codes */
#define XFS_BTREE_QUERY_RANGE_CONTINUE 0 /* keep iterating */
--
2.30.2