linux-kernel - Re: Linux & FAT32 label

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Date:   Mon, 16 Oct 2017 00:04:50 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Pavel Machek <pavel@....cz>
Cc:     Andreas Bombe <aeb@...ian.org>, Karel Zak <kzak@...hat.com>,
        util-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrius Štikonas <andrius@...konas.eu>,
        Curtis Gedak <gedakc@...il.com>
Subject: Re: Linux & FAT32 label

On Sunday 15 October 2017 08:59:01 Pavel Machek wrote:
> Hi!
> 
> > Based on results I would propose following unification:
> > 
> ...
> > 4. Prefer label from the root directory. If there is none entry (means
> >    there is also no erased entry), then read label from root sector.
> > 
> >    --> Reason: Windows XP and mlabel ignores what is written in boot
> >        sector. Windows XP even do not update boot sector, so label
> >        stored in boot sector is incorrect after any change done by
> >        Windows XP.
> > 
> >        But due to compatibility with older dosfslabel, which stores
> >        label only to boot sector, there is need for some fallback. Due
> >        to point 1. the best seems to be to process also erased label in
> >        root directory (marked with leading 0xE5) and fallback to boot
> >        sector only in case label in root directory is missing.
> > 
> > What do you think about it?
> 
> 4. seems dangerous. Assume we have "OLD" in boot sector and "0xe5-EW" in the directory
> entry. The label will change from <none> to "OLD" when the directory entry is reused by
> "FOO.TXT", right? That seems surprising / dangerous.

Hm... that is a good question what happen (I do not know). I think that
current situation when Windows XP show different label as Linux is also
_surprising_.

Do you have a better idea what to do and how to handle this situation?

-- 
Pali Rohár
pali.rohar@...il.com