linux-kernel - Re: [PATCH] xfs: Fix possible truncation of log data in xlog_bread

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Message-ID: <51310E7A.1000905@sgi.com>
Date:	Fri, 01 Mar 2013 14:24:26 -0600
From:	Mark Tinguely <tinguely@....com>
To:	Tony Lu <zlu@...era.com>
CC:	Alex Elder <elder@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Chris Metcalf <cmetcalf@...era.com>,
	"xfs@....sgi.com" <xfs@....sgi.com>, Ben Myers <bpm@....com>,
	Dave Chinner <dchinner@...hat.com>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH] xfs: Fix possible truncation of log data in xlog_bread_noalign()

On 03/01/13 09:51, Mark Tinguely wrote:
> On 02/26/13 01:28, Tony Lu wrote:
>> I get a reliable way to reproduce this bug. The logprint and metadump
>> are attached.
>>
>> Kernel version: 2.6.38.8
>> Mkfs.xfs version: xfsprogs-3.1.1
>> mkfs.xfs -s size=4096 /dev/sda1
>>
>> Run the following mount-cp-umount script to reproduce:
>> #!/bin/sh
>> device=/dev/sda1
>> mount_point=/mnt
>> times=10
>>
>> for ((num=1;num<=$times;num++))
>> do
>> echo "$num mount $device $mount_point"
>> mount $device $mount_point
>>
>> echo "cp -rf /bin $mount_point/$num"
>> cp -rf /bin $mount_point/$num
>>
>> echo "$num umount $device $mount_point"
>> umount $mount_point
>>
>> #num=$(($num + 1))
>> done
>>
>> After several times of mount/cp/umount, this xfs crashes, and the xfs
>> partition can not be mounted any more. Here is the output of console.
>> -sh-4.1# ./umount-test
>> 1 mount /dev/sda1 /mnt
>> XFS mounting filesystem sda1
>> cp -rf /bin /mnt/1
>> 1 umount /dev/sda1 /mnt
>> 2 mount /dev/sda1 /mnt
>> XFS mounting filesystem sda1
>> cp -rf /bin /mnt/2
>> 2 umount /dev/sda1 /mnt
>> 3 mount /dev/sda1 /mnt
>> XFS mounting filesystem sda1
>> cp -rf /bin /mnt/3
>> 3 umount /dev/sda1 /mnt
>> 4 mount /dev/sda1 /mnt
>> XFS mounting filesystem sda1
>> cp -rf /bin /mnt/4
>> 4 umount /dev/sda1 /mnt
>> 5 mount /dev/sda1 /mnt
>> XFS mounting filesystem sda1
>> Starting XFS recovery on filesystem: sda1 (logdev: internal)
>> Ending XFS recovery on filesystem: sda1 (logdev: internal)cp -rf /bin
>> /mnt/5
>> 5 umount /dev/sda1 /mnt
>> 6 mount /dev/sda1 /mnt
>>
>> XFS mounting filesystem sda1
>> Starting XFS recovery on filesystem: sda1 (logdev: internal)
>> Ending XFS recovery on filesystem: sda1 (logdev: internal)Interrupt
>> cp -rf /bin /mnt/6
>> 6 umount /dev/sda1 /mnt
>> 7 mount /dev/sda1 /mnt
>>
>> XFS mounting filesystem sda1
>> cp -rf /bin /mnt/7
>> 7 umount /dev/sda1 /mnt
>> Interrupt
>> 8 mount /dev/sda1 /mnt
>> XFS mounting filesystem sda1
>> Starting XFS recovery on filesystem: sda1 (logdev: internal)
>> XFS: xlog_recover_process_data: bad clientid
>> XFS: log mount/recovery failed: error 5
>> XFS: log mount failed
>>
>> Thanks
>> -Tony
>
> It works fine on a 2.6.32 machine I had sitting around - and I never
> required log recovery.
>
> I think you need to answer Dave's question as to why is your unmounts
> are requiring recovery?
>
> Are there errors in the /var/log/messages?
>
> I downloaded the Linux 2.6.38.8 source and take a look if I can recreate
> the problem.
>
> --Mark.

I could not reproduce the problem on a vanilla install. XFS shutdown and 
remounted cleanly running your script (several iterations looping set to 
100).

I started fsstress on another XFS partition on the same disk to see if I 
could force a shutdown race. With CONFIG_XFS_DEBUG=y, I could trigger 
other ASSERTs on the fsstress partition so I never stayed up long enough 
to cause a shutdown race.

Not wanting to patch that version of Linux/XFS, I am bailing here. If 
you want to turn on the XFS debug it may point out why your filesystem 
is not shutting down cleanly.

--Mark.
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