Method insert_trace

src/client/Client.cc:1752–1943

insert_trace * * insert a trace from a MDS reply into the cache. */

 * insert a trace from a MDS reply into the cache.
 */
Inode* Client::insert_trace(MetaRequest *request, MetaSession *session)
{
  auto& reply = request->reply;
  int op = request->get_op();

  ldout(cct, 10) << "insert_trace from " << request->sent_stamp << " mds." << session->mds_num
	   << " is_target=" << (int)reply->head.is_target
	   << " is_dentry=" << (int)reply->head.is_dentry
	   << dendl;

  auto p = reply->get_trace_bl().cbegin();
  if (request->got_unsafe) {
    ldout(cct, 10) << "insert_trace -- already got unsafe; ignoring" << dendl;
    ceph_assert(p.end());
    return NULL;
  }

  if (p.end()) {
    ldout(cct, 10) << "insert_trace -- no trace" << dendl;

    Dentry *d = request->dentry();
    if (d) {
      Inode *diri = d->dir->parent_inode;
      clear_dir_complete_and_ordered(diri, true);
    }

    if (d && reply->get_result() == 0) {
      if (op == CEPH_MDS_OP_RENAME) {
	// rename
	Dentry *od = request->old_dentry();
	ldout(cct, 10) << " unlinking rename src dn " << od << " for traceless reply" << dendl;
	ceph_assert(od);
	unlink(od, true, true);  // keep dir, dentry
      } else if (op == CEPH_MDS_OP_RMDIR ||
		 op == CEPH_MDS_OP_UNLINK) {
	// unlink, rmdir
	ldout(cct, 10) << " unlinking unlink/rmdir dn " << d << " for traceless reply" << dendl;
	unlink(d, true, true);  // keep dir, dentry
      }
    }
    return NULL;
  }

  ConnectionRef con = request->reply->get_connection();
  uint64_t features;
  if (session->mds_features.test(CEPHFS_FEATURE_REPLY_ENCODING)) {
    features = (uint64_t)-1;
  }
  else {
    features = con->get_features();
  }
  ldout(cct, 10) << " features 0x" << hex << features << dec << dendl;

  // snap trace
  SnapRealm *realm = NULL;
  if (reply->snapbl.length())
    update_snap_trace(session, reply->snapbl, &realm);