Method valid_till

src/test/osd/Object.h:366–371

      }

      uint64_t valid_till(uint64_t pos) {
	ceph_assert(covers(pos));
	return ranges.contains(pos) ?
	  ranges.end_after(pos) :
	  std::numeric_limits<uint64_t>::max();
      }
    };
    // from latest to earliest
    using layers_t = std::vector<ContState>;