Correct the sector calculation in map_buffer().
--- diff/drivers/md/dm-raid1.c	2003-10-16 10:44:23.000000000 +0100
+++ source/drivers/md/dm-raid1.c	2003-10-16 10:45:21.000000000 +0100
@@ -720,11 +720,7 @@
 static void map_buffer(struct mirror_set *ms,
 		       struct mirror *m, struct buffer_head *bh)
 {
-	sector_t bsize = bh->b_size >> 9;
-	sector_t rsector = bh->b_blocknr * bsize;
-
-	bh->b_rdev = m->dev->dev;
-	bh->b_rsector = m->offset + (rsector - ms->ti->begin);
+	bh->b_rsector = m->offset + (bh->b_rsector - ms->ti->begin);
 }
 
 static void do_reads(struct mirror_set *ms, struct buffer_list *reads)