diff -urpN linux-2.6-xfs5/fs/xfs/xfs_mount.h linux-2.6-xfs6/fs/xfs/xfs_mount.h
--- linux-2.6-xfs5/fs/xfs/xfs_mount.h	2008-04-22 04:06:44.000000000 +0200
+++ linux-2.6-xfs6/fs/xfs/xfs_mount.h	2008-04-22 12:13:17.000000000 +0200
@@ -471,11 +471,17 @@ xfs_get_perag(struct xfs_mount *mp, xfs_
 	return &mp->m_perag[XFS_INO_TO_AGNO(mp, ino)];
 }
 
+/* Macro (instead of inline) makes gcc understand that params are not used
+ * and emit "unused" warnings *in callers* if they otherwise are not using
+ * variables passed to xfs_put_perag. We want to know that. */
+#define xfs_put_perag(mp, pag) ((void)0)
+#if 0
 static inline void
 xfs_put_perag(struct xfs_mount *mp, xfs_perag_t *pag)
 {
 	/* nothing to see here, move along */
 }
+#endif
 
 /*
  * Per-cpu superblock locking functions