[PATCH] Disable buggy raid5 handling of read-ahead

raid5 tries to honour RWA_MASK, but messes it up and can return bad data.
Just ignore RAW_MASK for now.

drivers/md/raid5.c

@@ -1326,7 +1326,7 @@ static int make_request (request_queue_t *q, struct bio * bi)
 			(unsigned long long)new_sector, 
 			(unsigned long long)logical_sector);
 
-		sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
+		sh = get_active_stripe(conf, new_sector, pd_idx, 0/*(bi->bi_rw&RWA_MASK)*/);
 		if (sh) {
 
 			add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK));