Method read_object

src/librbd/io/ObjectRequest.cc:223–256

template <typename I>
void ObjectReadRequest<I>::read_object() {
  I *image_ctx = this->m_ictx;

  std::shared_lock image_locker{image_ctx->image_lock};
  auto read_snap_id = this->m_io_context->get_read_snap();
  if (read_snap_id == image_ctx->snap_id &&
      image_ctx->object_map != nullptr &&
      !image_ctx->object_map->object_may_exist(this->m_object_no)) {
    image_ctx->asio_engine->post([this]() { read_parent(); });
    return;
  }
  image_locker.unlock();

  ldout(image_ctx->cct, 20) << "snap_id=" << read_snap_id << dendl;

  neorados::ReadOp read_op;
  for (auto& extent: *this->m_extents) {
    if (extent.length >= image_ctx->sparse_read_threshold_bytes) {
      read_op.sparse_read(extent.offset, extent.length, &extent.bl,
                          &extent.extent_map);
    } else {
      read_op.read(extent.offset, extent.length, &extent.bl);
    }
  }
  util::apply_op_flags(
    m_op_flags, image_ctx->get_read_flags(read_snap_id), &read_op);

  image_ctx->rados_api.execute(
    {data_object_name(this->m_ictx, this->m_object_no)},
    *this->m_io_context, std::move(read_op), nullptr,
    librbd::asio::util::get_callback_adapter(
      [this](int r) { handle_read_object(r); }), m_version,
      (this->m_trace.valid() ? this->m_trace.get_info() : nullptr));
}

template <typename I>
void ObjectReadRequest<I>::handle_read_object(int r) {