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https://issues.apache.org/jira/browse/HDFS-4842?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jing Zhao updated HDFS-4842:
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Attachment: HDFS-4842.001.patch
The patch implementing the second kind of fix.
> Snapshot: identify the correct prior snapshot when deleting a snapshot under
> a renamed subtree
> ----------------------------------------------------------------------------------------------
>
> Key: HDFS-4842
> URL: https://issues.apache.org/jira/browse/HDFS-4842
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Affects Versions: 3.0.0
> Reporter: Jing Zhao
> Assignee: Jing Zhao
> Attachments: HDFS-4842.000.patch, HDFS-4842.001.patch
>
>
> In our long-term running tests for snapshot we find the following bug:
> 1. initially we have directories /test, /test/dir1 and /test/dir2/foo.
> 2. first take snapshot s0 and s1 on /test.
> 3. modify some descendant of foo (e.g., delete foo/bar/file), to make sure
> some changes have been recorded to the snapshot diff associated with s1.
> 4. take snapshot s2 on /test/dir2
> 5. move foo from dir2 to dir1, i.e., rename /test/dir2/foo to /test/dir1/foo
> 6. delete snapshot s1
> After step 6, the snapshot copy of foo/bar/file should have been merged from
> s1 to s0 (i.e., s0 should be identified as the prior snapshot of s1).
> However, the current code failed to identify the correct prior snapshot in
> the source tree of the rename operation and wrongly used s2 as the prior
> snapshot.
> The bug only exists when nested snapshottable directories are enabled. To fix
> the bug, we need to go upwards in the source tree of the rename operation
> (i.e., dir2) to identify the correct prior snapshot in the above scenario.
> This jira will fix the bug and add several corresponding unit tests.
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