[Bug 1481117] Re: casper 1.340.1 breaks previous persistency

[Adam Conrad]

Hello Adrien, or anyone else affected,

Accepted casper into trusty-proposed. The package will build now and be
available at https://launchpad.net/ubuntu/+source/casper/1.340.2 in a
few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to
enable and use -proposed.  Your feedback will aid us getting this update
out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, and change the tag
from verification-needed to verification-done. If it does not fix the
bug for you, please add a comment stating that, and change the tag to
verification-failed.  In either case, details of your testing will help
us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Also affects: casper (Ubuntu Wily)
   Importance: Medium
     Assignee: Andy Whitcroft (apw)
       Status: In Progress

** Also affects: casper (Ubuntu Trusty)
   Importance: Undecided
       Status: New

** Also affects: casper (Ubuntu Vivid)
   Importance: Undecided
       Status: New

** Changed in: casper (Ubuntu Trusty)
       Status: New => Fix Committed

** Tags added: verification-needed

** Changed in: casper (Ubuntu Trusty)
     Assignee: (unassigned) => Andy Whitcroft (apw)

** Changed in: casper (Ubuntu Vivid)
     Assignee: (unassigned) => Andy Whitcroft (apw)

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https://bugs.launchpad.net/bugs/1481117

Title:
  casper 1.340.1 breaks previous persistency

Status in casper package in Ubuntu:
  In Progress
Status in casper source package in Trusty:
  Fix Committed
Status in casper source package in Vivid:
  New
Status in casper source package in Wily:
  In Progress

Bug description:
  Likely scenario (unless I missed a crucial piece of information):

  - User has a working persistency file (or partition), with an Ubuntu 14.04.2 ISO
  - User upgrades to an Ubuntu 14.04.3 ISO, and boots it with the same persistency settings

  Likely result:

  - It appears to the user that the persistent data is lost

  Cause:

  - In casper 1.340, persistency data is stored in the root of the persistency partition
  - In casper 1.340.1, persistency data is stored in the /upper directory of the persistency partition

  Actual issue I faced:

  - I maintain a personal, custom Kubuntu ISO. Nothing too fancy: it is just the regular Kubuntu ISO, with many additional packages (digikam, darktable, etc.; all from the official Ubuntu repository). I regularly update my ISO by chrooting in the uncompressed squashfs and running aptitude there. I have a script to rebuild the ISO afterwards.
  - Today's update brought me casper 1.340.1, which broke my persistency as described above
  - Additionally, since I'm still running Linux 3.16, casper.log also featured a magnificent red herring:

  > mount: mounting /cow on /root failed: Invalid argument

  It took me a while to understand that the mount was actually
  successful (the first mount with the workdir option fails and emits
  the message, the second mount succeeds silently).

  My solution was quite simply:

  - Boot without persistency
  - Mount the persistent partition
  - Empty the /upper directory that had been created when I first booted with casper 1.340.1
  - Move data from the root of the persistent partition to the /upper directory
  - Reboot with persistency

  I'm not sure all users of the persistency feature will be as adept at
  fixing their persistency partition. It is surprising to see such an
  incompatible change introduced in a minor update of an LTS version.

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