Hi,

On Fri, May 21, 2010 at 4:16 PM,  <[email protected]> wrote:
>
> Joonwoo Park:
>> Sorry for confusion.
>> # mount -t ubifs -o rw /dev/brabra /mnt
>> # ls -al /mnt
>> (error occurs here, .wh.dir doesn't appear)
>
> It seems that is the problem of ubifs.
>

According to your explanation about the plnk, I'm also inclined it is
not aufs issue.

>
>> No, I'm not using aufs2-util at all.
>
> aufs2-util is necessary.
> But I don't know that is the root cause of the problem.
>

Okay, I see.

>
>> I don't think I fully understand what .wh..wh.plnk is for.
>> But I was under the impression somehow .wh..wh.plnk keep changes.
>> That's why I was curious that how it's synced.
>>
>> But it sounds like it's changes only when filesystem is
>> remount/umount.  is it true?
>
> When you handle a hardllinked file, an internal hidden hardlink is
> created under .wh..wh.plnk. And it is restored to the RW branch when you
> remount/umount. This is doen by aufs2-util.
> For instance,
> - /u = /rw + /ro
> - /ro/fileA and /ro/fileB are hardlinked.
> - when you modify /u/fileA, aufs copies-up to /rw/fileA and create a
>  hardlink /rw/.wh..wh.plnk/XX.YY.
> - when you remount/unmount /u, aufs2-util is invoked. aufs2-util creates
>  /rw/fileB and removes /rw/.wh..wh.plnk/XX.YY.
>

Thank you for your explanation.
At that time I'm pretty sure I never touched hard linked file.
Moreover even if I touched and power cycled without sync plnk,
at least UBIFS should have had truncated file without error.
So now I think problem is not on aufs.

Thanks again.
Joonwoo.

>
> J. R. Okajima
>

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