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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is missing log files that will aid in diagnosing the problem.
>From a terminal window please run:

apport-collect 1381968

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
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This change has been made by an automated script, maintained by the
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** Changed in: linux (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1381968

Title:
  Fstrim destroys data on loopback device

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  I've upgraded Ubuntu Server 12.04 LTS to 14.04 LTS.

  The setup contains a loopback device (/dev/loop3) mounted into a
  software raid 1 (/dev/md2).

  After the weekly cronjob (/etc/cron.weekly/fstrim) ran, I've
  discovered that it wiped all data on the loopback device from the
  raid.

  fstrim-all skips check because the loopback device is part of device mapper raid.
  if [ "${REALDEV#/dev/dm-}" != "$REALDEV" ]; then
          echo "device $DEV is on devmapper, skipping TRIM feature check"

  Issue can be reproduced on raid setup and plain loopback mount setup!

  Here is step-by-step how to reproduce the issue:

  1.) create sparse image file
  dd of=/sparse-file bs=1k seek=1024000

  2.) losetup loopback device
  losetup /dev/loop3 /sparse-file

  3.) create raid1
  mdadm --create /dev/md2 --auto md --level=1 --raid-devices=1 /dev/loop3

  4.) create fs
  mkfs.ext4 /dev/md2

  4.1.) check sparse-file size
  ls -lash /sparse-file

  5.) mount and copy data
  mount /dev/md2 /mnt
  copy some random files on /mnt

  5.1.) check sparse-file size again
  ls -lash /sparse-file -> size indicates it contains the copied data

  6.) destroy loopback via fstrim
  fstrim -v /mnt

  7.) data is wiped
  umount /mnt
  ls -lash /sparse-file -> size indicates that all data is wiped out!
  fsck -v -f /dev/md2 -> will report infinite errors on filesystem

  I could not find any similiar bugreport.

  Best Regards
  Daniel

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