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