[Bug 921403] [NEW] duplicate files when listing NFS exporting ext4 with large number of files

[Chris Adamson]

Public bug reported:

When a directory on an NFS server contained within an ext4 filesystem
contains a large number of files (I was able to reliably produce the bug
with 450000 and 500000 files respectively), an ls command on a client
will produce duplicate files or get caught in an infinite loop on one
file and continuously allocate more and more RAM.

I wrote a simple program to process the directory entries (hacked the
example on the getdents man page) and can reliably reproduce the bug.
The program prints out a filename if the previous file was the same name
and the position and previous position of the pointer in the directory
entry:

file1 585952 586024
file2 428896 428968
file3 761616 761688
file4 996264 996344
file4 996344 996424
file4 996424 996504
file4 996504 996584
file4 996584 996664
....
the file4 entries repeat forever

I googled and found these pages that explain the issue:

https://bugzilla.redhat.com/show_bug.cgi?id=739222
http://marc.info/?l=linux-nfs&m=131281788003178&w=2

This problem does not occur with an XFS filesystem and occurs with NFSv3
and NFSv4.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: nfs-kernel-server 1:1.2.2-4ubuntu5.1
ProcVersionSignature: Ubuntu 2.6.38-13.53-generic 2.6.38.8
Uname: Linux 2.6.38-13-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Wed Jan 25 16:46:03 2012
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110426)
ProcEnviron:
 SHELL=/bin/bash
 PATH=(custom, user)
 LANG=en_AU.UTF-8
 LANGUAGE=en_AU:en
SourcePackage: nfs-utils
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: nfs-utils (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug natty

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https://bugs.launchpad.net/bugs/921403

Title:
  duplicate files when listing NFS exporting ext4 with large number of
  files

Status in “nfs-utils” package in Ubuntu:
  New

Bug description:
  When a directory on an NFS server contained within an ext4 filesystem
  contains a large number of files (I was able to reliably produce the
  bug with 450000 and 500000 files respectively), an ls command on a
  client will produce duplicate files or get caught in an infinite loop
  on one file and continuously allocate more and more RAM.

  I wrote a simple program to process the directory entries (hacked the
  example on the getdents man page) and can reliably reproduce the bug.
  The program prints out a filename if the previous file was the same
  name and the position and previous position of the pointer in the
  directory entry:

  file1 585952 586024
  file2 428896 428968
  file3 761616 761688
  file4 996264 996344
  file4 996344 996424
  file4 996424 996504
  file4 996504 996584
  file4 996584 996664
  ....
  the file4 entries repeat forever

  I googled and found these pages that explain the issue:

  https://bugzilla.redhat.com/show_bug.cgi?id=739222
  http://marc.info/?l=linux-nfs&m=131281788003178&w=2

  This problem does not occur with an XFS filesystem and occurs with
  NFSv3 and NFSv4.

  ProblemType: Bug
  DistroRelease: Ubuntu 11.04
  Package: nfs-kernel-server 1:1.2.2-4ubuntu5.1
  ProcVersionSignature: Ubuntu 2.6.38-13.53-generic 2.6.38.8
  Uname: Linux 2.6.38-13-generic x86_64
  NonfreeKernelModules: nvidia
  Architecture: amd64
  Date: Wed Jan 25 16:46:03 2012
  InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110426)
  ProcEnviron:
   SHELL=/bin/bash
   PATH=(custom, user)
   LANG=en_AU.UTF-8
   LANGUAGE=en_AU:en
  SourcePackage: nfs-utils
  UpgradeStatus: No upgrade log present (probably fresh install)

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