Re: [PATCH] Add CONFIG_VFAT_NO_CREATE_WITH_LONGNAMES option

Paul E. McKenney
2009-05-02T04:51:21Z

On Fri, May 01, 2009 at 07:59:28PM -0600, Matthew Wilcox wrote:
> On Fri, May 01, 2009 at 06:37:29PM -0700, Paul E. McKenney wrote:
> > On Fri, May 01, 2009 at 05:01:09PM -0400, Christoph Hellwig wrote:
> > > >From the complete lack of technical arguments it's pretty obvious that
> > > this seems to be some FUD fallout from the MS vs TomTom patent lawsuite.
> > >
> > > I'm not a lawyer so I don't know how much of a threat it is. But either
> > > the case gets shot down by showing prior art and everything is fine, or
> > > we indeed are in deep trouble and should remove it completely. Given
> > > the Cc list on here IBM seems to have some legal opinion on it, so can
> > > we please see it and discuss what we want to with all cards on the
> > > table?
> >
> > Hello, Christoph!
> >
> > Hmmm... Both Tridge and Dave have Signed-off-by on the original patch,
> > and Steve has Acked-by, Mingming has Cc, and Dave is on the From list
> > rather than the Cc list, so I have to guess that there is a good chance
> > that you are talking about me. ;-)
> >
> > However, as far as I know, none of us are lawyers, and LKML is definitely
> > a technical rather than a legal forum, so we really do need to stick to
> > technical topics. I understand that this might be a bit frustrating
> > to you. On the other hand, I for one much prefer being in a forum
> > restricted to technical topics than to be in those places designed to
> > handle legal topics!
>
> So what's the purely technical argument for including this patch?

Pretty much what it says in the config-variable description in the patch
itself. To recap, with some technical elaboration:

1. It allows you to read VFAT media, mixed-case long names and all.
Full compatibility for reading from existing media.

2. It allows opening existing mixed-case long-named files
both for reading and writing.

3. For file creation, only the 8.3-format filename is permitted.
Such a name can be stored in a single VFAT directory entry.

4. It allows you to create files with both uppercase and lowercase
8.3-format names, as long as the 8-character portion is either
entirely uppercase or entirely lowercase, and as long as
the 3-character extension is either entirely uppercase
or entirely lowercase. This again keeps the name confined
to a single VFAT directory entry.

>From the original patch, with a couple additional examples added:

o Creating FILE1234.TXT is allowed.

o Creating FILE12345.TXT or FILE1234.TEXT is prohibited, as
neither fits the 8.3 format.

o Creating FILE.TXT, FILE.txt, file.TXT, and file.txt would all
be allowed, and would create files by exactly those names.

o Attempting to create File.TxT will give you a file named FILE.TXT.

There you have it!

Thanx, Paul