Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754652AbZKTRZQ (ORCPT ); Fri, 20 Nov 2009 12:25:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754233AbZKTRZQ (ORCPT ); Fri, 20 Nov 2009 12:25:16 -0500 Received: from cantor.suse.de ([195.135.220.2]:44140 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753574AbZKTRZP (ORCPT ); Fri, 20 Nov 2009 12:25:15 -0500 Date: Fri, 20 Nov 2009 18:25:19 +0100 From: Jan Blunck To: Jamie Lokier Cc: linux-fsdevel@vger.kernel.org, Christoph Hellwig , Alan Cox , Linux-Kernel Mailinglist , Andrew Morton , Thomas Gleixner , jkacur@redhat.com, Arnd Bergmann , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Willem Riede , "James E.J. Bottomley" Subject: Re: [PATCH 02/15] osst: Use noop_llseek() instead of default_llseek() Message-ID: <20091120172519.GA21750@bolzano.suse.de> References: <1258735245-25826-1-git-send-email-jblunck@suse.de> <1258735245-25826-3-git-send-email-jblunck@suse.de> <20091120170906.GG20634@shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091120170906.GG20634@shareable.org> Organization: SUSE LINUX Products GmbH, GF Markus Rex, HRB 16746 (AG Nuernberg) User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1747 Lines: 48 On Fri, Nov 20, Jamie Lokier wrote: > Jan Blunck wrote: > > __os_scsi_tape_open() suggests that llseek() doesn't work: > > "We really want to do nonseekable_open(inode, filp); here, but some > > versions of tar incorrectly call lseek on tapes and bail out if that > > fails. So we disallow pread() and pwrite(), but permit lseeks." > > > > Instead of using the fallback default_llseek() the driver should use > > noop_llseek() which leaves the file->f_pos untouched but succeeds. > > st.c has the same comment, but I didn't see a patch for st.c in the series. > Right, that would make sense. I wonder if anyone has this weird tar and could test if it actually works. -- st: Use noop_llseek() instead of default_llseek() st_open() suggests that llseek() doesn't work: "We really want to do nonseekable_open(inode, filp); here, but some versions of tar incorrectly call lseek on tapes and bail out if that fails. So we disallow pread() and pwrite(), but permit lseeks." Instead of using the fallback default_llseek() the driver should use noop_llseek() which leaves the file->f_pos untouched but succeeds. Signed-off-by: Jan Blunck --- diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c index 12d58a7..9f03668 100644 --- a/drivers/scsi/st.c +++ b/drivers/scsi/st.c @@ -3958,6 +3958,7 @@ static const struct file_operations st_fops = .open = st_open, .flush = st_flush, .release = st_release, + .llseek = noop_llseek, }; static int st_probe(struct device *dev) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/