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From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Gwendal
 Grignou <gwendal@chromium.org>, dlunev@chromium.org
Subject: Re: [PATCH] fat: ignore .. subdir and always add a link to dirs
In-Reply-To: <Ze2IAnSX7lr1fZML@quatroqueijos.cascardo.eti.br> (Thadeu Lima de
	Souza Cascardo's message of "Sun, 10 Mar 2024 07:14:26 -0300")
References: <87bk88oskz.fsf@mail.parknet.co.jp>
	<Zdf8qPN5h74MzCQh@quatroqueijos.cascardo.eti.br>
	<874jdzpov7.fsf@mail.parknet.co.jp>
	<87zfvroa1c.fsf@mail.parknet.co.jp>
	<ZdhsYAUCe9GVMnYE@quatroqueijos.cascardo.eti.br>
	<87v86fnz2o.fsf@mail.parknet.co.jp>
	<Zd6PdxOC8Gs+rX+j@quatroqueijos.cascardo.eti.br>
	<87le75s1fg.fsf@mail.parknet.co.jp>
	<Zd74fjlVJZic8UxI@quatroqueijos.cascardo.eti.br>
	<87h6hek50l.fsf@mail.parknet.co.jp>
	<Ze2IAnSX7lr1fZML@quatroqueijos.cascardo.eti.br>
Date: Sun, 10 Mar 2024 23:59:34 +0900
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Thadeu Lima de Souza Cascardo <cascardo@igalia.com> writes:

>> If we really want to accept this image, we have to change the fat driver
>> without affecting good image.  And your patch affects to good image,
>> because that patch doesn't count directory correctly, so bad link count.
>> 
>
> Well, it does behave the same on a correct image. It ignores the existence of
> ".." when counting subdirs, but always adds an extra link count.
>
> So, images that have both "." and ".." subdirs, will have the 2 links, both
> with the patch and without the patch.

You are forgetting to count about normal dirs other than "." and ".."?

Thanks.

> Images with neither dirs will be rejected before the patch and have a link
> count of 1 after the patch. Still, creating and removing subdirs will work.
> Removing the bad dir itself also works.
>
> Images with only "." or only ".." would have a link count of 1 and be rejected
> without the patch.
>
> With the patch, directories with only ".." should behave the same as if they
> had neither subdirs. That is, link count of 1. And directories with only "."
> will have a link count of 2.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>