void freeAllEntriesOnDisk(LocalRegion region) {
    if (region == null) {
      return;
    }
    region.foreachRegionEntry(regionEntry -> {
      DiskEntry de = (DiskEntry) regionEntry;
      DiskId id = de.getDiskId();
      if (id != null) {
        synchronized (id) {
          id.unmarkForWriting();
          if (EntryBits.isNeedsValue(id.getUserBits())) {
            long oplogId = id.getOplogId();
            long offset = id.getOffsetInOplog();
            // int length = id.getValueLength();
            if (oplogId != -1 && offset != -1) {
              id.setOplogId(-1);
              OverflowOplog oplog = getDiskStore().overflowOplogs.getChild((int) oplogId);
              if (oplog != null) {
                oplog.freeEntry(de);
              }
            }
          }
        }
      }
    });
  }
Only called on overflow-only regions. Needs to take every entry currently using disk storage
and free up that storage
geode-core/src/main/java/org/apache/geode/internal/cache/DiskRegion.java