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https://issues.apache.org/jira/browse/HDFS-6527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14030707#comment-14030707
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Kihwal Lee commented on HDFS-6527:
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Instead of moving inode removal inside lock, we could have getAdditionalBlock()
to do additional check after acquiring the FSN write lock. One possibility is
to have it acquire FSDirectory read lock and check the parent of the inode. If
deleted, it should be null. Or we could make checkLease() do more than just
checking the clientName recorded in the inode.
> Edit log corruption due to defered INode removal
> ------------------------------------------------
>
> Key: HDFS-6527
> URL: https://issues.apache.org/jira/browse/HDFS-6527
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.4.0
> Reporter: Kihwal Lee
> Assignee: Kihwal Lee
> Priority: Blocker
> Attachments: HDFS-6527.branch-2.4.patch, HDFS-6527.trunk.patch
>
>
> We have seen a SBN crashing with the following error:
> {panel}
> \[Edit log tailer\] ERROR namenode.FSEditLogLoader:
> Encountered exception on operation AddBlockOp
> [path=/xxx,
> penultimateBlock=NULL, lastBlock=blk_111_111, RpcClientId=,
> RpcCallId=-2]
> java.io.FileNotFoundException: File does not exist: /xxx
> {panel}
> This was caused by the deferred removal of deleted inodes from the inode map.
> Since getAdditionalBlock() acquires FSN read lock and then write lock, a
> deletion can happen in between. Because of deferred inode removal outside FSN
> write lock, getAdditionalBlock() can get the deleted inode from the inode map
> with FSN write lock held. This allow addition of a block to a deleted file.
> As a result, the edit log will contain OP_ADD, OP_DELETE, followed by
> OP_ADD_BLOCK. This cannot be replayed by NN, so NN doesn't start up or SBN
> crashes.
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