linux-kernel - Re: [PATCH] f2fs: fix up f2fs_get_parent issue to retrieve correct parent inode number

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Date:	Wed, 12 Dec 2012 09:12:54 -0800
From:	Leon Romanovsky <leon@...n.nu>
To:	Fubo Chen <fubo.chen@...il.com>
Cc:	Namjae Jeon <linkinjeon@...il.com>, jaegeuk.kim@...sung.com,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH] f2fs: fix up f2fs_get_parent issue to retrieve correct
 parent inode number

On Wed, Dec 12, 2012 at 8:50 AM, Fubo Chen <fubo.chen@...il.com> wrote:
> On Wed, Dec 12, 2012 at 5:12 PM, Leon Romanovsky <leon@...n.nu> wrote:
>> On Wed, Dec 12, 2012 at 7:05 AM, Fubo Chen <fubo.chen@...il.com> wrote:
>>>
>>> On Wed, Dec 12, 2012 at 3:37 PM, Namjae Jeon <linkinjeon@...il.com> wrote:
>>> > +       /* dot and dotdot dentries should have zero-value hash code */
>>> > +       if (!memcmp(name, ".", 1) || !memcmp(name, "..", 2))
>>> > +               return 0;
>>>
>>> That looks suspicious. If memcmp(name, "..", 2) == 0 then always
>>> memcmp(name, ".", 1) == 0. Why two tests ?
>>
>> It is not the case vice versa, so you still need to do two checks.
>> You need to distinguish dot(.), dotdot(..) and something with dot at
>> the beginning (for example - .o)
>
> Thanks for replying. I understand that the intention is what you
> explained. But to me the code says something else: "if the first byte
> of name is a dot, return 0". Did I see that correctly ?
Excellent catch, I agree with you It will also return 0 for every file
which starts from the dot.
The right solution must take name length into account.

>
> Fubo.



-- 
Leon Romanovsky | Independent Linux Consultant
        www.leon.nu | leon@...n.nu
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