rbd: drop rbd_do_op() opcode and flags

The only callers of rbd_do_op() are in rbd_rq_fn(), where call one
is used for writes and the other used for reads.  The request passed
to rbd_do_op() already encodes the I/O direction, and that
information can be used inside the function to set the opcode and
flags value (rather than passing them in as arguments).

So get rid of the opcode and flags arguments to rbd_do_op().

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

drivers/block/rbd.c

@@ -1164,7 +1164,6 @@ static int rbd_do_op(struct request *rq,
 		     struct rbd_device *rbd_dev,
 		     struct ceph_snap_context *snapc,
 		     u64 snapid,
-		     int opcode, int flags,
 		     u64 ofs, u64 len,
 		     struct bio *bio,
 		     struct rbd_req_coll *coll,
@@ -1176,6 +1175,8 @@ static int rbd_do_op(struct request *rq,
 	int ret;
 	struct ceph_osd_req_op *ops;
 	u32 payload_len;
+	int opcode;
+	int flags;
 
 	seg_name = rbd_segment_name(rbd_dev, ofs);
 	if (!seg_name)
@@ -1183,7 +1184,15 @@ static int rbd_do_op(struct request *rq,
 	seg_len = rbd_segment_length(rbd_dev, ofs, len);
 	seg_ofs = rbd_segment_offset(rbd_dev, ofs);
 
-	payload_len = (flags & CEPH_OSD_FLAG_WRITE ? seg_len : 0);
+	if (rq_data_dir(rq) == WRITE) {
+		opcode = CEPH_OSD_OP_WRITE;
+		flags = CEPH_OSD_FLAG_WRITE|CEPH_OSD_FLAG_ONDISK;
+		payload_len = seg_len;
+	} else {
+		opcode = CEPH_OSD_OP_READ;
+		flags = CEPH_OSD_FLAG_READ;
+		payload_len = 0;
+	}
 
 	ret = -ENOMEM;
 	ops = rbd_create_rw_ops(1, opcode, payload_len);
@@ -1519,16 +1528,11 @@ static void rbd_rq_fn(struct request_queue *q)
 			if (do_write)
 				(void) rbd_do_op(rq, rbd_dev,
 						snapc, CEPH_NOSNAP,
-						CEPH_OSD_OP_WRITE,
-						CEPH_OSD_FLAG_WRITE |
-						    CEPH_OSD_FLAG_ONDISK,
 						ofs, op_size, bio,
 						coll, cur_seg);
 			else
 				(void) rbd_do_op(rq, rbd_dev,
 						NULL, rbd_dev->mapping.snap_id,
-						CEPH_OSD_OP_READ,
-						CEPH_OSD_FLAG_READ,
 						ofs, op_size, bio,
 						coll, cur_seg);
 next_seg: