Method handle_client_session

src/mds/Server.cc:596–892

}

void Server::handle_client_session(const cref_t<MClientSession> &m)
{
  version_t pv;
  Session *session = mds->get_session(m);

  dout(3) << "handle_client_session " << *m << " from " << m->get_source() << dendl;
  ceph_assert(m->is_a_client()); // should _not_ come from an mds!

  if (!session) {
    dout(0) << " ignoring sessionless msg " << *m << dendl;
    auto reply = make_message<MClientSession>(CEPH_SESSION_REJECT);
    reply->metadata["error_string"] = "sessionless";
    mds->send_message(reply, m->get_connection());
    return;
  }

  std::string_view fs_name = mds->mdsmap->get_fs_name();
  if (!fs_name.empty() && !session->fs_name_capable(fs_name, MAY_READ)) {
    dout(0) << " dropping message not allowed for this fs_name: " << *m << dendl;
    auto reply = make_message<MClientSession>(CEPH_SESSION_REJECT);
    reply->metadata["error_string"] = "client doesn't have caps for FS \"" +
				      std::string(fs_name) + "\"";
    mds->send_message(std::move(reply), m->get_connection());
    return;
  }

  if (m->get_op() == CEPH_SESSION_REQUEST_RENEWCAPS) {
    // always handle renewcaps (state >= MDSMap::STATE_RECONNECT)
  } else if (m->get_op() == CEPH_SESSION_REQUEST_CLOSE) {
    // close requests need to be handled when mds is active
    if (mds->get_state() < MDSMap::STATE_ACTIVE) {
      mds->wait_for_active(new C_MDS_RetryMessage(mds, m));
      return;
    }
  } else {
    if (mds->get_state() < MDSMap::STATE_CLIENTREPLAY) {
      mds->wait_for_replay(new C_MDS_RetryMessage(mds, m));
      return;
    }
  }

  if (logger)
    logger->inc(l_mdss_handle_client_session);

  uint64_t sseq = 0;
  switch (m->get_op()) {
  case CEPH_SESSION_REQUEST_OPEN:
    if(mds->mdsmap->test_flag(CEPH_MDSMAP_REFUSE_CLIENT_SESSION)) {
      dout(0) << "new sessions are not permitted, enable again via"
                 "`ceph fs set <fs_name> refuse_client_session false`" << dendl;
      auto reply = make_message<MClientSession>(CEPH_SESSION_REJECT);
      reply->metadata["error_string"] = "new sessions are not permitted,"
                                        " enable again via `ceph fs set"
                                        " <fs_name> refuse_client_session false`";
      mds->send_message(reply, m->get_connection());
      return;
    }
    if (!session->client_opened) {