linux-kernel - Re: Error testing ext3 on brd ramdisk

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Message-ID: <49AFC1A9.90501@dti2.net>
Date:	Thu, 05 Mar 2009 13:12:25 +0100
From:	"Jorge Boncompte [DTI2]" <jorge@...2.net>
To:	npiggin@...e.de
CC:	ext-adrian.hunter@...ia.com, LKML <linux-kernel@...r.kernel.org>
Subject: Re: Error testing ext3 on brd ramdisk

Jorge Boncompte [DTI2] escribió:
> Nick Piggin escribió:
>> On Thu, Mar 05, 2009 at 10:19:46AM +0100, Jorge Boncompte [DTI2] wrote:
>>> Nick Piggin escribió:
>>>>> ------------
>>>>> mount -no remount,ro /dev/ram0
>>>>> dd if=/dev/ram0 of=config.bin bs=1k count=1000
>>>>> mount -no remount,rw /dev/ram0
>>>>> md5sum config.bin
>>>>> dd if=config.bin of=/dev/hda1
>>>>> echo $md5sum | dd of=/dev/hda1 bs=1k seek=1100 count=32
>>>>> ------------
>>>>>
>>>>> on system boot
>>>>>
>>>>> ------------
>>>>> CHECK MD5SUM
>>>>> dd if=/dev/hda1 of=/dev/ram0 bs=1k count=1000
>>>>> fsck.minix -a /dev/ram0
>>>>> mount -nt minix /dev/ram0 /etc -o rw
>>>>> ------------
>>>>>
>>>>>     I have never seen a MD5 failure on boot, just sometimes the 
>>>>>     filesystem is corrupted. Kernel config attached.
>>>> >From your description, it suggests that the corrupted image is being
>>>> read from /dev/ram0 (becuase the md5sum passes).
>>>     No, it is read from /dev/hda1.
>>
>> No I mean when it is first read from /dev/ram0 when you create the
>> image. Can you put some fsx.minix checks on the image file to try
>> to narrow down when exactly it is getting corrupted?
> 
> Ok. I have modified the script to do...
> ------------
> mount -no remount,ro /dev/ram0
> dd if=/dev/ram0 of=/tmp/config.bin bs=1k count=1000
> fsck.minix -fv /tmp/config.bin
> if [ $? != 0 ]; then
>     echo "FATAL: Filesystem is corrupted"
>     exit 2
> fi
> mount -no remount,rw /dev/ram0
> md5sum config.bin
> dd if=config.bin of=/dev/hda1
> echo $md5sum | dd of=/dev/hda1 bs=1k seek=1100 count=32
> ------------
> ... after some cycles of modifying files on the filesystem and trying to 
> save it to disk...
> ------------------
> fsck.minix: BusyBox v1.8.2 (2008-12-03 14:24:56 CET)
> Forcing filesystem check on /tmp/config.bin
> Unused inode 198 is marked as 'used' in the bitmap.
> Zone 393 is marked 'in use', but no file uses it.
> Zone 394 is marked 'in use', but no file uses it.
> 
>    198 inodes used (58%)
>    395 zones used (39%)
> 
>    163 regular files
>     24 directories
>      0 character device files
>      0 block device files
>      0 links
>     10 symbolic links
> ------
>    197 files
> FATAL: Filesystem is corrupted
> -------------------
> 

	If after getting the "FATAL: Filesystem is corrupted" message I do 
"echo 3 > /proc/sys/vm/drop_caches" and rerun the script the filesystem 
somehow got magically fixed (I mean fsck.minix does not report errors 
and the image gets written to disk well ;-)

-- 
==============================================================
Jorge Boncompte - Ingenieria y Gestion de RED
DTI2 - Desarrollo de la Tecnologia de las Comunicaciones
--------------------------------------------------------------
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Tlf: +34 957 761395 / FAX: +34 957 450380
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