  void finish(int r) override {
    RWLock::RLocker l(osd->pg_map_lock);
    for (auto p : pgs) {
      if (osd->pg_map.count(p->info.pgid)) {
        p->ch = store->open_collection(p->coll);
        assert(p->ch);
      }
    }
  }
  void finish(int r) override {
    RWLock::RLocker l(osd->pg_map_lock);
    for (auto p : pgs) {
      if (osd->pg_map.count(p->info.pgid)) {
        p->ch = store->open_collection(p->coll);
        assert(p->ch);
      }
    }
  }