[PATCH 20/47] xfs: increase XFS_BTREE_MAXLEVELS to fit the rmapbt

[Darrick J. Wong]

By my calculations, a 1,073,741,824 block AG with a 1k block size
can attain a maximum height of 9.  Assuming a record size of 24
bytes, a key/ptr size of 44 bytes, and half-full btree nodes,
we'd need 53,687,092 blocks for the records and ~6 million blocks
for the keys.  That requires a btree of height 9.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/xfs/libxfs/xfs_btree.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index b8bbb21..629ef4f 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -133,7 +133,7 @@ do {    \
 	}       \
 } while (0)
 
-#define	XFS_BTREE_MAXLEVELS	8	/* max of all btrees */
+#define	XFS_BTREE_MAXLEVELS	9	/* max of all btrees */
 
 struct xfs_btree_ops {
 	/* size of the key and record structures */