blockdev doesn't work as reported with loop devices

[Ketil]

SRU Justification:
[Impact]
blockdev won't work correctly with loopback devices.

[Test Case]
1) Create and mount a loop back device on /dev/loop0
2) Run:
$ sudo blockdev --report /dev/loop0
This should work without an ioctl error.

[Regression Potential]
This patch is backported from an upstream release commit 569d1dac.
Its already in utopic, and the patch modifies the program to no longer use an invalid ioctl call.

--

According to blockdev's manual:

       --report
              Print a report for the specified device. It is possible to give
              multiple devices. If none is given, all devices which appear in
              /proc/partitions are shown. Note that the partition StartSec is
              in 512-byte sectors.

However, I'm running Ubuntu installed with wubi, so my root dev is on a loopback device. Here's my /proc/partitions:

major minor #blocks name

   7 0 30457856 loop0
   7 1 31457280 loop1
   8 0 732574584 sda
   8 1 26214400 sda1
   8 2 307263488 sda2
   8 3 1 sda3
   8 5 399092736 sda5

So according to the manual, all these devices should be printed with blockdev --report. But they are not, the loop devices are excluded:

$ sudo blockdev --report
[sudo] password for user:
RO RA SSZ BSZ StartSec Size Device
rw 256 512 4096 0 750156374016 /dev/sda
rw 256 512 4096 2048 26843545600 /dev/sda1
rw 256 512 4096 52430848 314637811712 /dev/sda2
rw 256 512 1024 666957824 1024 /dev/sda3
rw 256 512 4096 666959872 408670961664 /dev/sda5
$

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: util-linux 2.20.1-5.1ubuntu2
ProcVersionSignature: Ubuntu 3.5.0-27.46-generic 3.5.7.7
Uname: Linux 3.5.0-27-generic x86_64
ApportVersion: 2.6.1-0ubuntu10
Architecture: amd64
Date: Sun Apr 28 23:48:07 2013
InstallationDate: Installed on 2012-04-12 (381 days ago)
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
MarkForUpload: True
SourcePackage: util-linux
UpgradeStatus: Upgraded to quantal on 2012-11-15 (164 days ago)

[Ketil (ketil-froyn)]

Turns out blockdev is actually getting an ioctl error on loop devices when run with --report. I had only tested a few values directly, eg using --getsz. Perhaps that is why this happens?

$ sudo blockdev --report /dev/loop0
RO RA SSZ BSZ StartSec Size Device
blockdev: ioctl error on /dev/loop0
$ sudo blockdev --g
60915712
$

[Chris J Arges (arges)]

This works correctly in Utopic (2.25-8ubuntu3).

[Chris J Arges (arges)]

Uploaded fix for Trusty.

[Brian Murray (brian-murray)]

Hello Ketil, or anyone else affected,

Accepted util-linux into trusty-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/util-linux/2.20.1-5.1ubuntu20.2 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!

[Ketil (ketil-froyn)]

Proposed package works for me, and I confirmed again that the version I had before upgrading had the same issue. From apt-get output:

Unpacking util-linux (2.20.1-5.1ubuntu20.2) over (2.20.1-5.1ubuntu20.1) ...

I don't see where I can change verification-needed to verification-done, however. Hopefully someone else can take care of that.

[Launchpad Janitor (janitor)]

This bug was fixed in the package util-linux - 2.20.1-5.1ubuntu20.2

---------------
util-linux (2.20.1-5.1ubuntu20.2) trusty; urgency=medium

  * Backport of 569d1dac to fix invalid ioctl when blockdev is called against
    loopback devices. (LP: #1174098)
 -- Chris J Arges <email address hidden> Mon, 22 Sep 2014 15:21:59 -0500

[Colin Watson (cjwatson)]

The verification of the Stable Release Update for util-linux has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.