--- 2.3.18ac9-mapbug/drivers/block/ll_rw_blk.c.~1~	Tue Sep 14 14:35:35 1999
+++ 2.3.18ac9-mapbug/drivers/block/ll_rw_blk.c	Tue Sep 28 02:25:36 1999
@@ -416,10 +416,6 @@
 	count = bh->b_size >> 9;
 	sector = bh->b_rsector;
 
-	/* We'd better have a real physical mapping! */
-	if (!buffer_mapped(bh))
-		BUG();
-
 	/* It had better not be a new buffer by the time we see it */
 	if (buffer_new(bh))
 		BUG();
@@ -479,6 +475,13 @@
                                " must be R/W/RA/WA\n");
 			goto end_io;
 	}
+
+	/* We'd better have a real physical mapping!
+	   Check this bit only if the buffer was dirty and just locked
+	   down by us so at this point flushpage will block and
+	   won't clear the mapped bit under us. */
+	if (!buffer_mapped(bh))
+		BUG();
 
 /* look for a free request. */
        /* Loop uses two requests, 1 for loop and 1 for the real device.