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From "Brandon Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5329) Update FSNamesystem#getListing() to handle inode path in startAfter token
Date Fri, 11 Oct 2013 21:39:42 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13793063#comment-13793063
] 

Brandon Li commented on HDFS-5329:
----------------------------------

NFS server returns the directory modification time to NFS clients.
If the client noticed the directory is changed(e,g., the startAfter file is deleted, or other
files are added),  NFS client implements would redo the directory listing from the beginning,
or accept whatever returned by the server. Given NFS gateway always returns directory mtime
along with the listing result, it's acceptable that HDFS lists the directory form the beginning
if the startAfter file can't be found. 

> Update FSNamesystem#getListing() to handle inode path in startAfter token
> -------------------------------------------------------------------------
>
>                 Key: HDFS-5329
>                 URL: https://issues.apache.org/jira/browse/HDFS-5329
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>            Reporter: Brandon Li
>            Assignee: Brandon Li
>         Attachments: HDFS-5329.1.patch, HDFS-5329.2.patch, HDFS-5329.3.patch, HDFS-5329.patch
>
>
> This is to support network protocols which can't use file name as the token to resume
directory listing. 
> NFS gateway doesn't know the name of startAfter and has to use inode id instead. NFS
protocol uses readdir and readdirplus to list directory content. In the response, each dirent
has an 8-byte number verifier.
> To list the content of large directories, NFS client sends multiple readdir or readdirplus
requests to NFS gateway with one verifier(resume point) in the request. The verifier is basically
of the same usage as "startAfter" in getListing. Since NFSv3 uses file handle to communicate
and doesn't know the file name. NFS gateway has to use the inode id path as "startAfter" when
sending getList request to NN, however NN currently expects "startAfter" to be just a file
name. As a result, NFS gateway can't list the content of large directories.



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