Btrfs devel - Mar 2013 - Kernel BUG on corrupted space cache under 3.7 and 3.8

Dear list members,

Yesterday I was about to restart my computer and that''s why I closed
every
opened applications: three Eclipse instances, two other Java applications, 2 
web browsers etc. It involved a lot of IO operations and before everything 
could settle down my system became unresponsive.

I mean X & co. worked fine, but anything related to IO (opening a new
screen, a
new application etc.) hung. My process explorer showed that nearly all of the 
applications which were shutting down have very high IO, but in fact there 
were no HDD head movement at all. I did a hard reset.

Today morning when I restarted Linux I got a kernel BUG from btrfs. I 
successfully started a recovery Linux (with kernel 3.7) and when I tried to 
mount this partition, the bug/panic appeared again. After I could rebuild the 
space cache with clear_cache option and my system was fixed.

Since all this logs are written only onto screen, I made some photographs :), 
and I uploaded them.

System parameters:
- openSUSE 12.3, Kernel 3.8, x86_64
- Linux linux-suse 3.8.0-5-desktop #1 SMP PREEMPT Tue Feb 26 20:55:05 UTC 2013 
(db497a6) x86_64 x86_64 x86_64 GNU/Linux
- Photos are made on Kernel 3.7
- Default mount options: compress=lzo,space_cache
- On 3.7, the problematic line: fs/btrfs/free-space-cache.c:1553
- Photos location: www.morrohun.hu/temp/btrfs/[123].jpeg

If you need any other information, ask me :).

Best regards,

Ákos Szőts
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On Tue, Mar 26, 2013 at 05:37:35AM -0600, Szőts Ákos
wrote:
> Dear list members,
> 
> Yesterday I was about to restart my computer and that''s why I
closed every
> opened applications: three Eclipse instances, two other Java applications,
2
> web browsers etc. It involved a lot of IO operations and before everything 
> could settle down my system became unresponsive.
> 
> I mean X & co. worked fine, but anything related to IO (opening a new
screen, a
> new application etc.) hung. My process explorer showed that nearly all of
the
> applications which were shutting down have very high IO, but in fact there 
> were no HDD head movement at all. I did a hard reset.
> 
> Today morning when I restarted Linux I got a kernel BUG from btrfs. I 
> successfully started a recovery Linux (with kernel 3.7) and when I tried to
> mount this partition, the bug/panic appeared again. After I could rebuild
the
> space cache with clear_cache option and my system was fixed.
> 
> Since all this logs are written only onto screen, I made some photographs
:),
> and I uploaded them.
> 
> System parameters:
> - openSUSE 12.3, Kernel 3.8, x86_64
> - Linux linux-suse 3.8.0-5-desktop #1 SMP PREEMPT Tue Feb 26 20:55:05 UTC
2013
> (db497a6) x86_64 x86_64 x86_64 GNU/Linux
> - Photos are made on Kernel 3.7
> - Default mount options: compress=lzo,space_cache
> - On 3.7, the problematic line: fs/btrfs/free-space-cache.c:1553
> - Photos location: www.morrohun.hu/temp/btrfs/[123].jpeg
> 
> If you need any other information, ask me :).
> 
Ok so I''ve just made a bunch of changes to btrfs-image so I can capture
your
tree log and free space cache so I can reproduce exactly this issue :).  Can you
clone this tree

git://github.com/josefbacik/btrfs-progs.git

and then build and run

btrfs-image -c9 /dev/whatever blah.img

and upload blah.img somewhere so I can pull it down?  If you''ve already
fixed
the file system so it mounts then I don''t need the image, I need it
only if it
is still panicing.  So if you have already fixed it then still please clone that
tree and next time it happens capture the fs image if you could so I can
reproduce and fix the problem.  Thanks,

Josef
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I fixed my file system here, so I can''t provide more details now.

Anyway, I cloned your repository and successfully compiled the tree
(except for the mkfs program). But when I try to issue the command
"./btrfs-image -c9 /dev/sda7 /home/linux/image.img" I get the
following:

Could not open /dev/sda7
Open ctree failed

I tried when it was unmounted and also when was mounted.

An other thing happened in the meantime, but I write it to an other
thread, because that''s an other bug :).

Ákos
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I could "successfully" reproduce this issue while I was upgrading from
3.8 to 3.9. All the symptoms are exactly the same as I''ve written a
month ago, nothing changed.
I''ll send you the link to the corrupted image file in a private mail.

Btw, under Gentoo (SystemRescueCD to be precise) there are three
warning in the btrfs-progs: http://pastebin.com/rYam2jWb

Ákos
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