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>
diff --git a/include/linux/dm-io.h b/include/linux/dm-io.h
index a68cbe5..b91b023 100644
--- a/include/linux/dm-io.h
+++ b/include/linux/dm-io.h
@@ -57,7 +57,8 @@
  */
 struct dm_io_client;
 struct dm_io_request {
-	int bi_rw;			/* READ|WRITE - not READA */
+	int bi_op;			/* REQ_OP */
+	int bi_op_flags;		/* rq_flag_bits */
 	struct dm_io_memory mem;	/* Memory to use for io */
 	struct dm_io_notify notify;	/* Synchronous if notify.fn is NULL */
 	struct dm_io_client *client;	/* Client memory handler */