btrfs-convert does not work (unable to open ctree)

[Andrea Agnolin]

I've tried to convert an ext4 partition on /dev/sda3 to btrfs
I've run an "e2fsck -vyf" and everything was ok
Then I run btrfs-convert:

# btrfs-convert /dev/sda3
No valid Btrfs found on /dev/sda3
unable to open ctree
conversion aborted.

$ uname -a
Linux gamma 3.11.0-7-generic #14-Ubuntu SMP Mon Sep 16 18:37:27 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: btrfs-tools 0.19+20130705-1
ProcVersionSignature: Ubuntu 3.11.0-7.14-generic 3.11.1
Uname: Linux 3.11.0-7-generic x86_64
ApportVersion: 2.12.4-0ubuntu1
Architecture: amd64
Date: Fri Sep 20 19:38:28 2013
InstallationDate: Installed on 2012-10-19 (335 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
MarkForUpload: True
SourcePackage: btrfs-tools
UpgradeStatus: Upgraded to saucy on 2013-09-12 (7 days ago)

[Rolf (rolf-redhat-bugs)]

Description of problem:
When trying to convert an ext4 FS to BTRFS btrfs-convert refuses claiming "No valid Btrfs found in /dev/mapper/BCACHE-ROOTFS'

Version-Release number of selected component (if applicable):
btrfs-progs-0.20.rc1.20130917git194aa4a-1.fc20.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Build a system running root on LVM
2. Boot an F20 Live DVD
3. yum install btrfs-progs
4. start btrfs-convert /dev/mapper/BCACHE-ROOTFS
5. Error: No valid Btrfs found on /dev/mapper/BCACHE-ROOTFS

Actual results:
No valid Btrfs found on /dev/mapper/BCACHE-ROOTFS
unable to open ctree
conversion aborted.

Expected results:
Smooth conversion

Additional info:
http://thread.gmane.org/gmane.comp.file-systems.btrfs/28290

[Rolf (rolf-redhat-bugs)]

The more simple case provide by "Additional info" can also be used to reproduce:

Quote:
  way to reproduce error:
  $ truncate -s 4G file
  $ mkfs.ext4 file #say yes to create fs on non block device.
  $ btrfs-convert file
   No valid Btrfs found on file
   unable to open ctree
   conversion aborted.

[Eric (eric-redhat-bugs)]

Yep, this was regression reported upstream some time ago. A patch to fix it has been sent to the list, but a month later upstream still hasn't merged it (or any other patches).

When upstream accepts the fix, we can update btrfs-progs in Fedora to fix this bug.

thanks,
-Eric

[Tim (tim-redhat-bugs)]

JFTR: This is also present in Fedora 19 and needs to be fixed there as well.

[Eric (eric-redhat-bugs)]

And still JFTR: If upstream ever accepts this (or for that matter any) patch, I'll gladly fix it.

"Upstream first" - live by the sword, die by the sword. ;)

Thanks,
-Eric

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[txemi (txemitron)]

It also happens with ext4

#lvcreate -L 2G -n test2.ext2 vg1
#mkfs.ext2 /dev/vg1/test2.ext2
#btrfs-convert /dev/vg1/test2.ext2
No valid Btrfs found on /dev/vg1/test2.ext2
unable to open ctree
conversion aborted.

[Andrea Agnolin (agno94)]

I compiled from
git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs.git
adding this patch
https://patchwork.kernel.org/patch/2828820/
and now everything works

[txemi (txemitron)]

I rebuilt ubuntu package adding same patch and worked for me too.

[pascal germroth (pascal-ensieve)]

Until the package includes the patch, these are the steps to compile it manually as per Andrea Agnolin's answer:

sudo apt-get build-dep btrfs-tools
git clone git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs.git
cd btrfs-progs
curl https://patchwork.kernel.org/patch/2828820/raw/ | git apply
make
sudo ./btrfs-convert /my/device

[Launchpad Janitor (janitor)]

This bug was fixed in the package btrfs-tools - 0.19+20130705-3

---------------
btrfs-tools (0.19+20130705-3) unstable; urgency=low

  * Import patch by Shilong Wang to resolve btrfs-convert (Closes:
    #724265) (LP: #1228302)

 -- Dmitrijs Ledkovs <email address hidden> Fri, 18 Oct 2013 23:47:16 +0100

[Andrea Agnolin (agno94)]

In saucy we still we the previous version:

apt-cache policy btrfs-tools
btrfs-tools:
  Installato: 0.19+20130705-1
  Candidato: 0.19+20130705-1
  Tabella versione:
 *** 0.19+20130705-1 0
        500 http://archive.ubuntu.com/ubuntu/ saucy/main amd64 Packages
        500 http://it.archive.ubuntu.com/ubuntu/ saucy/main amd64 Packages
        100 /var/lib/dpkg/status

[Tim (tim-redhat-bugs)]

With btrfs-progs-3.12-1.fc19.i686, this works for me now in Fedora 19.

[Eric (eric-redhat-bugs)]

Great, thanks for the feedback.