Method mount

src/client/Client.cc:6943–7060

}

int Client::mount(const std::string &mount_root, const UserPerm& perms,
		  bool require_mds, const std::string &fs_name)
{
  ceph_assert(is_initialized());

  /*
   * To make sure that the _unmount() must wait until the mount()
   * is done.
   */
  RWRef_t mref_writer(mount_state, CLIENT_MOUNTING, false);
  if (!mref_writer.is_first_writer()) // already mounting or mounted
    return 0;

  ldout(cct, 1) << __func__ << ": " << mount_root << " " << perms
                << " required_mds=" << require_mds << " fs_name=" << fs_name << dendl;

  std::unique_lock cl(client_lock);

  int r = subscribe_mdsmap(fs_name);
  if (r < 0) {
    lderr(cct) << "mdsmap subscription failed: " << cpp_strerror(r) << dendl;
    return r;
  }

  start_tick_thread(); // start tick thread

  if (require_mds) {
    while (1) {
      auto availability = mdsmap->is_cluster_available();
      if (availability == MDSMap::STUCK_UNAVAILABLE) {
        // Error out
        ldout(cct, 10) << "mds cluster unavailable: epoch=" << mdsmap->get_epoch() << dendl;
        return CEPH_FUSE_NO_MDS_UP;
      } else if (availability == MDSMap::AVAILABLE) {
        // Continue to mount
        break;
      } else if (availability == MDSMap::TRANSIENT_UNAVAILABLE) {
        // Else, wait.  MDSMonitor will update the map to bring
        // us to a conclusion eventually.
        wait_on_list(waiting_for_mdsmap);
      } else {
        // Unexpected value!
        ceph_abort();
      }
    }
  }

  if(mdsmap->test_flag(CEPH_MDSMAP_REFUSE_CLIENT_SESSION)) {
    lderr(cct) << "connections cannot be made while" 
                  " the flag refuse_client_session is set" << dendl;
    return -EACCES;
  }

  populate_metadata(mount_root.empty() ? "/" : mount_root);

  filepath fp(CEPH_INO_ROOT);
  if (!mount_root.empty()) {
    fp = filepath(mount_root.c_str());