Date: Fri, 20 Nov 2009 17:16:56 +0000
From: Jamie Lokier <jamie@shareable.org>
To: Jan Blunck <jblunck@suse.de>
Cc: linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@infradead.org>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Linux-Kernel Mailinglist <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Thomas Gleixner <tglx@linutronix.de>, jkacur@redhat.com,
       Arnd Bergmann <arnd@arndb.de>,
       =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
       Willem Riede <osst@riede.org>,
       "James E.J. Bottomley" <James.Bottomley@suse.de>
Subject: Re: [PATCH 03/15] osst: Update ppos instead of using file->f_pos
Message-ID: <20091120171656.GI20634@shareable.org>
References: <1258735245-25826-1-git-send-email-jblunck@suse.de> <1258735245-25826-4-git-send-email-jblunck@suse.de> <20091120171317.GH20634@shareable.org>
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Jamie Lokier wrote:
> Jan Blunck wrote:
> > osst_read()/osst_write() modify file->f_pos directly instead of the ppos
> > given to them. The VFS later updates the file->f_pos and overwrites it
> > with the value of ppos.
> 
> I notice st.c doesn't use or update file->f_pos (or *ppos), so
> userspace probably won't be caring about f_pos from osst.c (they're
> both SCSI tape drivers).  And osst.c doesn't use the value, it just
> increases it with each transfer.  It doesn't even reset the value to
> zero when rewinding the tape, so it's not that meaningful.
> 
> So how about just removing those modifications to file->f_pos from osst.c?

Or alternatively, perhaps they are missing from st.c.  I don't know,
but userspace can't have been all that dependent on the value :-)

-- Jamie
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