xfs: make the record pointer passed to query_range functions const

The query_range functions are supposed to call a caller-supplied
function on each record found in the dataset.  These functions don't
own the memory storing the record, so don't let them change the record.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/xfs_rtalloc.h

@@ -22,9 +22,9 @@ struct xfs_rtalloc_rec {
 };
 
 typedef int (*xfs_rtalloc_query_range_fn)(
-	struct xfs_trans	*tp,
-	struct xfs_rtalloc_rec	*rec,
-	void			*priv);
+	struct xfs_trans		*tp,
+	const struct xfs_rtalloc_rec	*rec,
+	void				*priv);
 
 #ifdef CONFIG_XFS_RT
 /*