From: Zheng Liu <gnehzuil.liu@gmail.com>
Subject: Re: "Unknown code" error when enabling metadata_csum on ext4 raid1
 device
Date: Thu, 2 Aug 2012 17:58:19 +0800
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On Wed, Aug 01, 2012 at 10:43:05PM -0500, Nick Semenkovich wrote:
[-- snip --]
> Sorry for the slow reply --
> 
> 
> I hadn't seen any "Corrupt dir inode" errors until now.
> 
> Before running the one-line patch above, I resynced the MD array and
> ran a quick fsck (via "touch /forcefsck" & reboot).
> 
> 
> Then,
> $ sudo misc/tune2fs -O metadata_csum /dev/md1
> 
> [says something about running e2fsck -D]
> 
> 
> Then I got a few dmesg errors like:
> 
> [128700.816091] JBD2: Spotted dirty metadata buffer (dev = md1,
> blocknr = 5243385). There's a risk of filesystem corruption in case of
> system crash.
> [128700.816106] JBD2: Spotted dirty metadata buffer (dev = md1,
> blocknr = 1057). There's a risk of filesystem corruption in case of
> system crash.
> 
> then a lot of
> 
> [128711.000677] EXT4-fs warning (device md1): dx_probe:647: dx entry:
> limit != root limit
> [128711.000679] EXT4-fs warning (device md1): dx_probe:732: Corrupt
> dir inode 7733251, running e2fsck is recommended.
> 
> 
> On my next command (sudo -s), I got an immediate kernel panic:
> 
> [128713.776475] EXT4-fs warning (device md1): dx_probe:732: Corrupt
> dir inode 7733251, running e2fsck is recommended.
> [128761.137143] BUG: unable to handle kernel NULL pointer dereference
> at           (null)
> [128761.137195] IP: [<ffffffff8121d448>] ext4_iget+0x498/0xa50
> [128761.137231] PGD 106651067 PUD 11cf41067 PMD 0
> [128761.137258] Oops: 0000 [#1] SMP
> [128761.137279] CPU 0
> [snip...]
> 
> Full panic @ http://web.mit.edu/semenko/Public/panic.txt

Hi Nick,

Thanks for testing my patch.  As you described above, it seems that
there still has some bugs when metadata_csum feature enabled.  I tried
to reproduce this bug, but I couldn't reproduce it in my sandbox.  I see
the full panic file, and it seems that the kernel is running on Ubuntu
distribution and it doesn't use a generic mainline kernel.  So IMHO
would you like to try a latest upstream kernel?  At least when the
problem happens again, it is easy for me to find out where goes wrong.
Thanks for your patient.

Regards,
Zheng