public FSDataInputStream fallbackToFsChecksum(int offCount) throws IOException {
    // checksumOffCount is speculative, but let's try to reset it less.
    boolean partOfConvoy = false;
    if (this.stream == null) {
      synchronized (streamNoFsChecksumFirstCreateLock) {
        partOfConvoy = (this.stream != null);
        if (!partOfConvoy) {
          this.stream = (link != null) ? link.open(hfs) : hfs.open(path);
        }
      }
    }
    if (!partOfConvoy) {
      this.useHBaseChecksum = false;
      this.hbaseChecksumOffCount.set(offCount);
    }
    return this.stream;
  }
Read from non-checksum stream failed, fall back to FS checksum. Thread-safe.
@param offCount For how many checksumOk calls to turn off the HBase checksum.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/FSDataInputStreamWrapper.java