I created a first patch. There may be some task to do refactoring.
- The main change in this patch is creating some methods to reduce the length of Namenodefsck#check.
- I confirmed that TestFsck was passed.
- As an aside, I'm trying to support the fsck for Erasure Coding in
HDFS-7687. I think we will create Namenodefsck#collectECBlockGroupsSummary, like Namenodefsck#collectBlocksSummary I created in this patch.
Please review it. Thank you.