xfs: reserve AG space for the refcount btree root
Reduce the max AG usable space size so that we always have space for
the refcount btree root.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index be7e3fc..effb64c 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -128,6 +128,8 @@
blocks++; /* finobt root block */
if (xfs_sb_version_hasrmapbt(&mp->m_sb))
blocks++; /* rmap root block */
+ if (xfs_sb_version_hasreflink(&mp->m_sb))
+ blocks++; /* refcount root block */
return mp->m_sb.sb_agblocks - blocks;
}