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https://issues.apache.org/jira/browse/HDFS-7707?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14303475#comment-14303475
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Kihwal Lee commented on HDFS-7707:
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The patch looks good except the unnecessary imports in FSNamesystem.java.
> Edit log corruption due to delayed block removal again
> ------------------------------------------------------
>
> Key: HDFS-7707
> URL: https://issues.apache.org/jira/browse/HDFS-7707
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.6.0
> Reporter: Yongjun Zhang
> Assignee: Yongjun Zhang
> Attachments: HDFS-7707.001.patch, HDFS-7707.002.patch,
> reproduceHDFS-7707.patch
>
>
> Edit log corruption is seen again, even with the fix of HDFS-6825.
> Prior to HDFS-6825 fix, if dirX is deleted recursively, an OP_CLOSE can get
> into edit log for the fileY under dirX, thus corrupting the edit log
> (restarting NN with the edit log would fail).
> What HDFS-6825 does to fix this issue is, to detect whether fileY is already
> deleted by checking the ancestor dirs on it's path, if any of them doesn't
> exist, then fileY is already deleted, and don't put OP_CLOSE to edit log for
> the file.
> For this new edit log corruption, what I found was, the client first deleted
> dirX recursively, then create another dir with exactly the same name as dirX
> right away. Because HDFS-6825 count on the namespace checking (whether dirX
> exists in its parent dir) to decide whether a file has been deleted, the
> newly created dirX defeats this checking, thus OP_CLOSE for the already
> deleted file gets into the edit log, due to delayed block removal.
> What we need to do is to have a more robust way to detect whether a file has
> been deleted.
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