osd_req_op_extent_update
osd_req_op_extent_update(req, ceph_wbc->op_idx, len);
osd_req_op_extent_update(req, ceph_wbc->op_idx, len);
osd_req_op_extent_update(req, 0, len);
extern void osd_req_op_extent_update(struct ceph_osd_request *osd_req,
EXPORT_SYMBOL(osd_req_op_extent_update);