Path getMergesDir(final RegionInfo hri) {
    return new Path(getTableDir(), hri.getEncodedName());
  }
Write out a split reference. Package local so it doesnt leak out of regionserver.
@param hri         {@link RegionInfo} of the destination
@param familyName  Column Family Name
@param f           File to split.
@param splitRow    Split Row
@param top         True if we are referring to the top half of the hfile.
@param splitPolicy A split policy instance; be careful! May not be full populated; e.g. if this
                   method is invoked on the Master side, then the RegionSplitPolicy will NOT
                   have a reference to a Region.
@return Path to created reference.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionFileSystem.java