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Re: [PATCH] xfs: Fix possible truncation of log data in xlog_bread_noali

To: Tony Lu <zlu@xxxxxxxxxx>
Subject: Re: [PATCH] xfs: Fix possible truncation of log data in xlog_bread_noalign()
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Fri, 01 Mar 2013 14:24:26 -0600
Cc: Alex Elder <elder@xxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, Chris Metcalf <cmetcalf@xxxxxxxxxx>, "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>, Ben Myers <bpm@xxxxxxx>, Dave Chinner <dchinner@xxxxxxxxxx>, "linux-fsdevel@xxxxxxxxxxxxxxx" <linux-fsdevel@xxxxxxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <5130CE9E.9080501@xxxxxxx>
References: <BAB94DBB0E89D8409949BC28AC95914C47C485E5@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <20130223000802.GB26081@dastard> <BAB94DBB0E89D8409949BC28AC95914C47C48702@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <20130223235546.GA5551@dastard> <BAB94DBB0E89D8409949BC28AC95914C47C488D8@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <20130224141017.GC5551@dastard> <BAB94DBB0E89D8409949BC28AC95914C47C49005@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <5130CE9E.9080501@xxxxxxx>
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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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