[jira] [Created] (HDFS-2770) Block reports may mark corrupt blocks pending deletion as non-corrupt

["Todd Lipcon (Created) (JIRA)" <ji...@apache.org>]

Block reports may mark corrupt blocks pending deletion as non-corrupt
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                 Key: HDFS-2770
                 URL: https://issues.apache.org/jira/browse/HDFS-2770
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: name-node
    Affects Versions: 0.23.0
            Reporter: Todd Lipcon
            Priority: Critical


It seems like HDFS-900 may have regressed in trunk since it was committed without a regression test. In HDFS-2742 I saw the following sequence of events:
- A block at replication 2 had one of its replicas marked as corrupt on the NN
- NN scheduled deletion of that replica in {{invalidateWork}}, and removed it from the block map
- The DN hosting that block sent a block report, which caused the replica to get re-added to the block map as if it were good
- The deletion request was passed to the DN and it deleted the block
- Now we're in a bad state, where the NN temporarily thinks that it has two good replicas, but in fact one of them has been deleted. If we lower replication of this block at this time, the one good remaining replica may be deleted.

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