Re: test file disappeared after -f, -r, --add-journal for write-journal device

[yizhan <yizhan@redhat.com>]

On 07/28/2016 09:22 AM, Shaohua Li wrote:
> On Wed, Jul 27, 2016 at 08:07:19AM -0400, Yi Zhang wrote:
>> Hello maintainer
>>
>> Here is another strange phenomenon I found after do -f, -r, --add-journal for write-journal device.
>>
>> Kernel version: 4.7.0-rc7
>> Steps I used:
>> mdadm --create --run /dev/md0 --level 4 --metadata 1.2 --raid-devices 7 /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5 /dev/loop6 /dev/loop7 --write-journal /dev/loop0 --bitmap=internal --bitmap-chunk=64M --chunk 512
>> mdadm --wait /dev/md0
>> mkfs.ext4 /dev/md0
>> mount -t ext4 /dev/md0 /mnt/fortest
>> cp bigfile /mnt/fortest &
>> wait
>> md5sum /mnt/fortest/bigfile > md5sum3
>> mdadm /dev/md0 -f /dev/loop0
> since loop0 is the journal device and it fails, we will mark the md0 readonly
> at this point. Filesystem can't do any write. It's possible the fortest/md5sum3
> files not hit disk yet, and are lost. I think your test should do a sync before
> mark journal disk failure.
I add sync operation before mark journal disk failure, this issue cannot 
be reproduced any more,

thanks
Yi
>> mdadm /dev/md0 -r /dev/loop0
>> umount /dev/md0 -l
>> mdadm -o /dev/md0
>> mdadm /dev/md0 --add-journal /dev/loop0
>> mdadm --wait /dev/md0
>> mdadm -D /dev/md0
>> mount /dev/md0 /mnt/fortest
>> md5sum /mnt/fortest/bigfile > md5sum2   #<----this test file disappeared
> If a sync is done before journal disk fails and you still see the file
> disappeared, it's a bug.
>
> Thanks,
> Shaohua
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