linux-kernel - Re: CIFS kernel module bug

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Date:	Fri, 30 Sep 2011 14:04:09 -0400
From:	Jeff Layton <jlayton@...ba.org>
To:	Anton Altaparmakov <aia21@....ac.uk>
Cc:	Steve French <sfrench@...ba.org>, linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org,
	LKML <linux-kernel@...r.kernel.org>,
	PWF Linux <pwf-linux@....cam.ac.uk>
Subject: Re: CIFS  kernel module bug

On Fri, 30 Sep 2011 14:58:58 +0100
Anton Altaparmakov <aia21@....ac.uk> wrote:

> Hi,
> 
> Looking at the current kernel (in Linus' repository on github) there is a silly logic bug in the cifs module in fs/cifs/cifsfs.c::cifs_llseek() there is this bit of code:
> 
> 	/*
> 	 * origin == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
> 	 * the cached file length
> 	 */
> 	if (origin != SEEK_SET || origin != SEEK_CUR) {
> 
> The logical or should be a logical and, i.e. this should be:
> 
> 	if (origin != SEEK_SET && origin != SEEK_CUR) {
> 
> As the code is at present that line is ALWAYS true because origin is ALWAYS either != SEEK_SET or != SEEK_CUR as if it equals one it cannot equal the other and vice versa…
> 
> So at the moment it always does the revalidation instead of only for SEEK_END, SEEK_DATA, and SEEK_HOLE.
> 
> Best regards,
> 
> 	Anton


Haha, good catch. Care to roll up a patch to fix that?

-- 
Jeff Layton <jlayton@...ba.org>
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