rbd: don't set data in rbd_osd_req_format_op()

Currently an object request has its osd request's data field set in
rbd_osd_req_format_op().  That assumes a single osd op per object
request, and that won't be the case for long.

Move the code that sets this out and into the caller.

Rename rbd_osd_req_format_op() to be just rbd_osd_req_format(),
removing the notion that it's doing anything op-specific.

This and the next patch resolve:
    http://tracker.ceph.com/issues/4658

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

drivers/block/rbd.c

@@ -1311,12 +1311,11 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
 		rbd_obj_request_complete(obj_request);
 }
 
-static void rbd_osd_req_format_op(struct rbd_obj_request *obj_request,
+static void rbd_osd_req_format(struct rbd_obj_request *obj_request,
 					bool write_request)
 {
 	struct rbd_img_request *img_request = obj_request->img_request;
 	struct ceph_osd_request *osd_req = obj_request->osd_req;
-	struct ceph_osd_data *osd_data = NULL;
 	struct ceph_snap_context *snapc = NULL;
 	u64 snap_id = CEPH_NOSNAP;
 	struct timespec *mtime = NULL;
@@ -1325,28 +1324,12 @@ static void rbd_osd_req_format_op(struct rbd_obj_request *obj_request,
 	rbd_assert(osd_req != NULL);
 
 	if (write_request) {
-		osd_data = &osd_req->r_data_out;
 		now = CURRENT_TIME;
 		mtime = &now;
 		if (img_request)
 			snapc = img_request->snapc;
-	} else {
-		osd_data = &osd_req->r_data_in;
-		if (img_request)
-			snap_id = img_request->snap_id;
-	}
-	if (obj_request->type != OBJ_REQUEST_NODATA) {
-		/*
-		 * If it has data, it's either a object class method
-		 * call (cls) or it's an extent operation.
-		 */
-		/* XXX This use of the ops array goes away in the next patch */
-		if (obj_request->osd_req->r_ops[0].op == CEPH_OSD_OP_CALL)
-			osd_req_op_cls_response_data(obj_request->osd_req, 0,
-						osd_data);
-		else
-			osd_req_op_extent_osd_data(obj_request->osd_req, 0,
-						osd_data);
+	} else if (img_request) {
+		snap_id = img_request->snap_id;
 	}
 	ceph_osdc_build_request(osd_req, obj_request->offset,
 			snapc, snap_id, mtime);
@@ -1576,6 +1559,8 @@ static int rbd_img_request_fill_bio(struct rbd_img_request *img_request,
 	resid = img_request->length;
 	rbd_assert(resid > 0);
 	while (resid) {
+		struct ceph_osd_request *osd_req;
+		struct ceph_osd_data *osd_data;
 		const char *object_name;
 		unsigned int clone_size;
 		u64 offset;
@@ -1601,14 +1586,18 @@ static int rbd_img_request_fill_bio(struct rbd_img_request *img_request,
 		if (!obj_request->bio_list)
 			goto out_partial;
 
-		obj_request->osd_req = rbd_osd_req_create(rbd_dev,
-						write_request, obj_request);
-		if (!obj_request->osd_req)
+		osd_req = rbd_osd_req_create(rbd_dev, write_request,
+						obj_request);
+		if (!osd_req)
 			goto out_partial;
+		obj_request->osd_req = osd_req;
 
-		osd_req_op_extent_init(obj_request->osd_req, 0,
-					opcode, offset, length, 0, 0);
-		rbd_osd_req_format_op(obj_request, write_request);
+		osd_data = write_request ? &osd_req->r_data_out
+					 : &osd_req->r_data_in;
+		osd_req_op_extent_init(osd_req, 0, opcode, offset, length,
+						0, 0);
+		osd_req_op_extent_osd_data(osd_req, 0, osd_data);
+		rbd_osd_req_format(obj_request, write_request);
 
 		/* status and version are initially zero-filled */
 
@@ -1725,7 +1714,7 @@ static int rbd_obj_notify_ack(struct rbd_device *rbd_dev,
 
 	osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_NOTIFY_ACK,
 					notify_id, ver, 0);
-	rbd_osd_req_format_op(obj_request, false);
+	rbd_osd_req_format(obj_request, false);
 
 	osdc = &rbd_dev->rbd_client->client->osdc;
 	obj_request->callback = rbd_obj_request_put;
@@ -1791,7 +1780,7 @@ static int rbd_dev_header_watch_sync(struct rbd_device *rbd_dev, int start)
 	osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_WATCH,
 				rbd_dev->watch_event->cookie,
 				rbd_dev->header.obj_version, start);
-	rbd_osd_req_format_op(obj_request, true);
+	rbd_osd_req_format(obj_request, true);
 
 	if (start)
 		ceph_osdc_set_request_linger(osdc, obj_request->osd_req);
@@ -1850,6 +1839,7 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
 			     u64 *version)
 {
 	struct rbd_obj_request *obj_request;
+	struct ceph_osd_data *osd_data;
 	struct ceph_osd_client *osdc;
 	struct page **pages;
 	u32 page_count;
@@ -1880,10 +1870,12 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
 	if (!obj_request->osd_req)
 		goto out;
 
+	osd_data = &obj_request->osd_req->r_data_in;
 	osd_req_op_cls_init(obj_request->osd_req, 0, CEPH_OSD_OP_CALL,
 					class_name, method_name,
 					outbound, outbound_size);
-	rbd_osd_req_format_op(obj_request, false);
+	osd_req_op_cls_response_data(obj_request->osd_req, 0, osd_data);
+	rbd_osd_req_format(obj_request, false);
 
 	osdc = &rbd_dev->rbd_client->client->osdc;
 	ret = rbd_obj_request_submit(osdc, obj_request);
@@ -2062,6 +2054,7 @@ static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
 
 {
 	struct rbd_obj_request *obj_request;
+	struct ceph_osd_data *osd_data;
 	struct ceph_osd_client *osdc;
 	struct page **pages = NULL;
 	u32 page_count;
@@ -2086,9 +2079,11 @@ static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
 	if (!obj_request->osd_req)
 		goto out;
 
+	osd_data = &obj_request->osd_req->r_data_in;
 	osd_req_op_extent_init(obj_request->osd_req, 0, CEPH_OSD_OP_READ,
 					offset, length, 0, 0);
-	rbd_osd_req_format_op(obj_request, false);
+	osd_req_op_extent_osd_data(obj_request->osd_req, 0, osd_data);
+	rbd_osd_req_format(obj_request, false);
 
 	osdc = &rbd_dev->rbd_client->client->osdc;
 	ret = rbd_obj_request_submit(osdc, obj_request);