public int sizeIndexOfAllocation(long offset) {
    int bucketNo = (int) (offset / bucketCapacity);
    assert bucketNo >= 0 && bucketNo < buckets.length;
    Bucket targetBucket = buckets[bucketNo];
    return targetBucket.sizeIndex();
  }
Free a block with the offset
@param offset block's offset
@return size freed
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketAllocator.java