[
https://issues.apache.org/jira/browse/HDFS-6414?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13999280#comment-13999280
]
Chris Nauroth commented on HDFS-6414:
-------------------------------------
See below for a CLI transcript showing one example of the bug. The expected
end result is that the setfattr -x removes the user.foo xattr. It doesn't
work, because it reads the state of the inode's most recent snapshot, which was
created before an {{XAttrFeature}} was attached to the inode. This causes it
to skip the call to {{INode#removeXAttrFeature}}.
I expect the fix is to change {{XAttrStorage#updateINodeXAttrs}} so that it
doesn't pass the latest snapshot ID in the 2 calls to
{{INode#getXAttrFeature}}. (Call the no-args overload instead.) This will
read the latest version of the inode state.
Let's also add unit tests covering this case. See
{{TestAclWithSnapshot#testModifyReadsCurrentState}} and
{{TestAclWithSnapshot#testRemoveReadsCurrentState}} for inspiration. The
important thing about these tests is to create a snapshot first, before adding
any xattrs. The current tests in {{TestXAttrWithSnapshot}} all add the xattrs
before creating a snapshot, which is why this particular bug wasn't caught.
Thanks to [~jingzhao] for reviewing my findings before I filed the issue.
{code}
> hadoop-3.0.0-SNAPSHOT/bin/hdfs dfs -mkdir /testSnapshotWithXattr
> hadoop-3.0.0-SNAPSHOT/bin/hdfs dfsadmin -allowSnapshot /testSnapshotWithXattr
Allowing snaphot on /testSnapshotWithXattr succeeded
> hadoop-3.0.0-SNAPSHOT/bin/hdfs dfs -createSnapshot /testSnapshotWithXattr
> snap1
Created snapshot /testSnapshotWithXattr/.snapshot/snap1
> hadoop-3.0.0-SNAPSHOT/bin/hdfs dfs -setfattr -n user.foo
> /testSnapshotWithXattr
> hadoop-3.0.0-SNAPSHOT/bin/hdfs dfs -getfattr -d /testSnapshotWithXattr
# file: /testSnapshotWithXattr
user.foo
> hadoop-3.0.0-SNAPSHOT/bin/hdfs dfs -setfattr -x user.foo
> /testSnapshotWithXattr
> hadoop-3.0.0-SNAPSHOT/bin/hdfs dfs -getfattr -d /testSnapshotWithXattr
# file: /testSnapshotWithXattr
user.foo
{code}
> xattr modification operations are based on state of latest snapshot instead
> of current version of inode.
> --------------------------------------------------------------------------------------------------------
>
> Key: HDFS-6414
> URL: https://issues.apache.org/jira/browse/HDFS-6414
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: HDFS XAttrs (HDFS-2006)
> Reporter: Chris Nauroth
> Fix For: HDFS XAttrs (HDFS-2006)
>
> Attachments: hdfs-6414.1.patch, hdfs-6414.2.patch
>
>
> {{XAttrStorage#updateINodeXAttrs}} modifies the inode's {{XAttrFeature}}
> based on reading its current state. However, the logic for reading current
> state is incorrect and may instead read the state of the latest snapshot. If
> xattrs have been changed after creation of that snapshot, then subsequent
> xattr operations may yield incorrect results.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
