dm: use bio op accessors

Separate the op from the rq_flag_bits and have dm
set/get the bio using bio_set_op_attrs/bio_op.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/md/dm-stripe.c

@@ -292,8 +292,8 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 		bio->bi_bdev = sc->stripe[target_bio_nr].dev->bdev;
 		return DM_MAPIO_REMAPPED;
 	}
-	if (unlikely(bio->bi_rw & REQ_DISCARD) ||
-	    unlikely(bio->bi_rw & REQ_WRITE_SAME)) {
+	if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
+	    unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) {
 		target_bio_nr = dm_bio_get_target_bio_nr(bio);
 		BUG_ON(target_bio_nr >= sc->stripes);
 		return stripe_map_range(sc, bio, target_bio_nr);