Use s->chunk_size in snapshot ctr rather than the (modified)
chunk_size var.
--- diff/drivers/md/dm-snap.c	2003-10-29 14:56:09.000000000 +0000
+++ source/drivers/md/dm-snap.c	2003-11-05 11:22:19.000000000 +0000
@@ -527,7 +527,7 @@
 	}
 
 	ti->private = s;
-	ti->split_io = chunk_size;
+	ti->split_io = s->chunk_size;
 
 	return 0;