Ubuntu
util-linux package

blkid man page needs to document BLKID_DEBUG values to help diagnose device type conflicts

Bug #452503 reported by Brian Murray
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
util-linux (Ubuntu)
Invalid
Wishlist
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Bug Description

Binary package hint: util-linux

My swap partition is no longer being mounted in karmic as blkid does not recognize it and exits with error code 2. It used to be LUKS partition, but I long ago mkswapped over it.

This can be recreated using the following procedure:

Works
1) dd if=/dev/zero of=/tmp/works bs=1M count=1
2) mkswap /tmp/works
3) file /tmp/works (appears as swap)
4) blkid /tmp/works (TYPE="swap")

Not work
1) dd if=/dev/zero of=/tmp/busted bs=1M count=1
2) dd if=<(printf "LUKS\xba\xbe") of=/tmp/busted conv=nocreat,notrunc
3) mkswap /tmp/busted
4) file /tmp/busted (appears as swap)
5) blkid /tmp/busted (nothing)
6) echo $? (return code 2)

Additionally using blkid from Jaunty, package version 2.14.2-1ubuntu4, shows the TYPE as swap.

ProblemType: Bug
Architecture: amd64
Date: Thu Oct 15 13:09:16 2009
DistroRelease: Ubuntu 9.10
Package: util-linux 2.16-1ubuntu4
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/zsh
ProcVersionSignature: Ubuntu 2.6.31-14.46-generic
SourcePackage: util-linux
Uname: Linux 2.6.31-14-generic x86_64

See original description
Revision history for this message
Brian Murray (brian-murray) wrote :
Kees Cook (kees)
description: updated
description: updated
tags: added: regression-potential
Revision history for this message
Scott James Remnant (Canonical) (canonical-scott) wrote :

As you've proved here, you've deliberately put two types of metadata into your partition.

We've never supported that. Remember that in jaunty we used vol_id, which should equally not recognise your swap partition.

Changed in util-linux (Ubuntu):
status: New → Won't Fix
Revision history for this message
Kees Cook (kees) wrote :

Why did it work correctly in Jaunty? Why doesn't blkid claim it's LUKS? Anyone migrating partitions around will end up with junk in them.

Changed in util-linux (Ubuntu):
status: Won't Fix → Confirmed
Kees Cook (kees)
summary: - blkid fails to recognize swap partition / file
+ mkswap fails to fully wipe swap partition / file (resulting in blkid not
+ seeing it)
Revision history for this message
Scott James Remnant (Canonical) (canonical-scott) wrote : Re: mkswap fails to fully wipe swap partition / file (resulting in blkid not seeing it)

mkswap has code to do this:

http://git.kernel.org/?p=utils/util-linux-ng/util-linux-ng.git;a=commit;h=ff3bed806863d1c2075d0efda70b39ea6af9ecba

Which version of mkswap did you use to create the swap partition?

Changed in util-linux (Ubuntu):
status: Confirmed → Incomplete
Revision history for this message
Kees Cook (kees) wrote :

Karmic: util-linux 2.16-1ubuntu4

Changed in util-linux (Ubuntu):
status: Incomplete → Confirmed
Revision history for this message
Kees Cook (kees) wrote :

mkswap: /tmp/busted: warning: don't erase bootbits sectors
        on whole disk. Use -f to force.

I wasn't reading output -- I saw the UUID go by and ignored the rest. Okay, next, how about blkid growing a way to report why it refused to identify a partition.

Changed in util-linux (Ubuntu):
status: Confirmed → Invalid
importance: Undecided → Wishlist
status: Invalid → Confirmed
summary: - mkswap fails to fully wipe swap partition / file (resulting in blkid not
- seeing it)
+ blkid needs --verbose to report device type conflicts
tags: removed: regression-potential
Revision history for this message
Antti Kaijanmäki (kaijanmaki) wrote : Re: blkid needs --verbose to report device type conflicts

you can get detailed debug output from blkid by doing:

    $ sudo su -
    # BLKID_DEBUG=0xffff blkid

As far as I know every mkfs.* should erase the whole superblock so that these bogus signatures are not left floating around and if they don't it's a bug in the mkfs utility. There's absolutely no way blkid can tell which signature is the correct one.

Kees Cook (kees)
summary: - blkid needs --verbose to report device type conflicts
+ blkid man page needs to document BLKID_DEBUG values to help diagnose
+ device type conflicts
Revision history for this message
Scott James Remnant (Canonical) (canonical-scott) wrote :

You should never need to document debugging stuff anywhere other than upstream (where this is all documented in a ML post)

Newer blkid is more verbose about error reporting (and can be made to explain it's issue), so marking this Invalid

Changed in util-linux (Ubuntu):
status: Confirmed → Invalid
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