void initHDFSBlocksDistribution() throws IOException {
    hdfsBlocksDistribution = computeHDFSBlocksDistribution(fs);
  }
Return the active file name that contains the real data.
<p>
For referenced hfile, we will return the name of the reference file as it will be used to
construct the StoreFileReader. And for linked hfile, we will return the name of the file being
linked.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFileInfo.java