From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anton Altaparmakov <aia21-KWPb1pKIrIJaa/9Udqfwiw@public.gmane.org>
Subject: CIFS  kernel module bug
Date: Fri, 30 Sep 2011 14:58:58 +0100
Message-ID: <A904EFBF-CBC1-4842-9E50-2A556103B8AA@cam.ac.uk>
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Cc: linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, samba-technical-w/Ol4Ecudpl8XjKLYN78aQ@public.gmane.org,
	LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	PWF Linux <pwf-linux-IE+S/cj2AuA2EctHIo1CcQ@public.gmane.org>
To: Steve French <sfrench-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>
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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 =3D=3D SEEK_END || SEEK_DATA || SEEK_HOLE =3D> we must reval=
idate
	 * the cached file length
	 */
	if (origin !=3D SEEK_SET || origin !=3D SEEK_CUR) {

The logical or should be a logical and, i.e. this should be:

	if (origin !=3D SEEK_SET && origin !=3D SEEK_CUR) {

As the code is at present that line is ALWAYS true because origin is AL=
WAYS either !=3D SEEK_SET or !=3D SEEK_CUR as if it equals one it canno=
t equal the other and vice versa=85

So at the moment it always does the revalidation instead of only for SE=
EK_END, SEEK_DATA, and SEEK_HOLE.

Best regards,

	Anton
--=20
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer, http://www.linux-ntfs.org/

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Subject: CIFS  kernel module bug
From: Anton Altaparmakov <aia21@cam.ac.uk>
Date: Fri, 30 Sep 2011 14:58:58 +0100
Cc: linux-cifs@vger.kernel.org, samba-technical@lists.samba.org,
        LKML <linux-kernel@vger.kernel.org>,
        PWF Linux <pwf-linux@ucs.cam.ac.uk>
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To: Steve French <sfrench@samba.org>
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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
-- 
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer, http://www.linux-ntfs.org/