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[Ken Sharp <1208978@xxxxxxxxxxxxxxxxxx>]

Okay, I think I can recreate this fairly reliably.

mkdir /tmp/original
mkdir /tmp/cow
mkdir /tmp/mountpoint

mount -t tmpfs none /tmp/mountpoint
mount -t aufs -o br:/tmp/cow:/tmp/original none /tmp/mountpoint

for j in {1..15} ; do dd count=$RANDOM if=/dev/zero
of=/tmp/original/data$j bs=5120 ; done

for i in {1..150} ; do echo $i ; rm /tmp/mountpoint/* 2>&- ; (for j in
{1..15} ; do dd count=$RANDOM if=/dev/zero of=/tmp/mountpoint/data$j
bs=5120 ; done) ; done

rm /tmp/cow

The for j statement is to create some original files that will be
changed. I just had it create random files.

The for i statement does the same thing but so that the new files are in
the copy-on-write folder. I tried creating one large file but it was
hard to recreate, so I used the loop to create a bunch of random-size
files, then remove them, then do it again.

Once cleaned I'm still left with an apparently full mount despite the
fact I have removed all the new files:

none                                1003M  955M   48M  96% /tmp/cow
none                                1003M  955M   48M  96% /tmp/mountpoint

There's a number of different issues that pop up here:

1. rm /tmp/mountpoint/* should be removing the new files I have created.
They are not being removed. rm reports that these files cannot be
removed. They should be removed and either show an empty directory, or
show the original files. Either way there should be some logic here that
results in those files being removed.

2. rm /tmp/cow removes the files but aufs/tmpfs do not see the change,
even though ls /tmp/cow and ls /tmp/mountpoint show empty directories.

There's something very wrong here.

My original test is slightly different in that it removed /tmp/cow/* in
the loop. For example:

for i in {1..150} ; do echo $i ; rm /tmp/cow/* 2>&- ; (for j in {1..15}
; do dd count=$RANDOM if=/dev/zero of=/tmp/mountpoint/data$j bs=5120 ;
done) ; done

Either way aufs/tmpfs seem to pick up the change for a while, then give
up and simply report the mount full.

Will try the mainline kernels tomorrow.

-- 
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https://bugs.launchpad.net/bugs/1208978

Title:
  Empty tmpfs mount reported as full

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  After using a tmpfs mount for a while it starts reporting that it is
  almost full and become unusable.

  $ mount ; df ; sudo ls -alR /tmp/test/

  <snip>
  none on /tmp/test type tmpfs (rw,uid=1000,gid=1000)
  none on /home/ken/.wine type aufs (rw,br:/tmp/test:/home/ken/.wine.dotnet20)

  Filesystem                           Size  Used Avail Use% Mounted on
  <snip>
  none                                1003M  881M  122M  88% /tmp/test
  none                                1003M  881M  122M  88% /home/ken/.wine

  /tmp/test/:
  total 12
  drwxrwxrwt  4 ken  ken    100 Aug  6 20:35 .
  drwxrwxrwt 10 root root 12288 Aug  6 20:38 ..
  -r--r--r--  1 root root     0 Aug  6 19:08 .wh..wh.aufs
  drwx------  2 root root    40 Aug  6 19:08 .wh..wh.orph
  drwx------  2 root root    40 Aug  6 19:08 .wh..wh.plnk

  /tmp/test/.wh..wh.orph:
  total 0
  drwx------ 2 root root  40 Aug  6 19:08 .
  drwxrwxrwt 4 ken  ken  100 Aug  6 20:35 ..

  /tmp/test/.wh..wh.plnk:
  total 0
  drwx------ 2 root root  40 Aug  6 19:08 .
  drwxrwxrwt 4 ken  ken  100 Aug  6 20:35 ..

  As you should be able to see the tmpfs mount on /tmp/test claims to be
  using ~900 MB but it's really only using a few bytes. It works
  perfectly for a while but then does this.

  I have been using the mount with aufs and the copy-on-write files are
  stored here. Since starting this report the "used" amount has dropped
  around 20 MB but there's no reason for this. There is no longer
  anything running that would use this directory.

  Nothing seems relevant in dmesg or the syslog.

  I don't know how to debug further.

  I will check the upstream kernel, but this is likely to cause other
  problems and will probably be difficult to recreate. I will report
  back once I know.

  Note to self: While testing
  http://bugs.winehq.org/show_bug.cgi?id=34217

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: linux-image-3.2.0-51-generic-pae 3.2.0-51.77
  ProcVersionSignature: Ubuntu 3.2.0-51.77-generic-pae 3.2.48
  Uname: Linux 3.2.0-51-generic-pae i686
  AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
  AplayDevices: aplay: device_list:252: no soundcards found...
  ApportVersion: 2.0.1-0ubuntu17.3
  Architecture: i386
  ArecordDevices: arecord: device_list:252: no soundcards found...
  AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/controlC0', '/dev/snd/hwC0D0', '/dev/snd/hwC0D1', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/pcmC0D1p', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
  CRDA: Error: [Errno 2] No such file or directory
  Date: Tue Aug  6 20:38:16 2013
  HibernationDevice: RESUME=UUID=113e73a6-3c10-4fbc-a9a4-5160e676d325
  InstallationMedia: Ubuntu-Server 12.04.1 LTS "Precise Pangolin" - Release i386 (20120817.3)
  Lsusb:
   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
   Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
  MachineType: Dell Inc. MM061
  MarkForUpload: True
  ProcEnviron:
   LANGUAGE=en_GB:en
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_GB.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-51-generic-pae root=UUID=0c3228e5-3952-43c1-b666-1c790f791025 ro persistent zcache
  PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
  RelatedPackageVersions:
   linux-restricted-modules-3.2.0-51-generic-pae N/A
   linux-backports-modules-3.2.0-51-generic-pae  N/A
   linux-firmware                                1.79.6
  RfKill: Error: [Errno 2] No such file or directory
  SourcePackage: linux
  StagingDrivers: zram
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 06/13/2007
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A17
  dmi.board.name: 0KD882
  dmi.board.vendor: Dell Inc.
  dmi.chassis.type: 8
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvrA17:bd06/13/2007:svnDellInc.:pnMM061:pvr:rvnDellInc.:rn0KD882:rvr:cvnDellInc.:ct8:cvr:
  dmi.product.name: MM061
  dmi.sys.vendor: Dell Inc.

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