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From: Jan Blunck <jblunck@suse.de>
To: Oliver Neukum <oliver@neukum.org>
Cc: "Jamie Lokier" <jamie@shareable.org>,
	"Alan Cox" <alan@lxorguk.ukuu.org.uk>,
	linux-fsdevel@vger.kernel.org,
	"Linux-Kernel Mailinglist" <linux-kernel@vger.kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	jkacur@redhat.com, "Thomas Gleixner" <tglx@linutronix.de>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH 1/2] BKL: Remove BKL from default_llseek()
Date: Wed, 18 Nov 2009 18:55:40 +0100	[thread overview]
Message-ID: <20091118175540.GR21750@bolzano.suse.de> (raw)
In-Reply-To: <200911181835.55007.oliver@neukum.org>

On Wed, Nov 18, Oliver Neukum wrote:

> Am Mittwoch, 18. November 2009 18:27:30 schrieb Jamie Lokier:
> > > No. Your logic is flawed
> > > 
> > > The BKL is protected something here - it protects the change of offset
> > > with respect to other BKL users within drivers. The question is what if
> > > anything in any other driver code depends upon the BKL and uses it to
> > > protect f_pos. Probably very little if anything but a grep for f_pos
> > > through the drivers might not be a bad idea before assuming this. Very
> > > few touch f_pos except in their own llseek method.
> > 
> > Of course, drivers shouldn't be using f_pos outside their llseek
> > method, as they should all behave the same with pread/pwrite as with
> > llseek+read/write.
> 
> Might not a driver update f_pos after read/write?

Actually the VFS is doing that for you in read/write syscall. So anything you
change in your driver gets corrected (or overwritten anyway).

Regards,
	Jan

-- 
Jan Blunck <jblunck@suse.de>

  parent reply	other threads:[~2009-11-18 17:55 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-18 16:07 Jan Blunck
2009-11-18 16:07 ` [PATCH 2/2] BKL: Update documentation on llseek( \b) Jan Blunck
2009-11-18 17:15 ` [PATCH 1/2] BKL: Remove BKL from default_llseek() Alan Cox
2009-11-18 17:27   ` Jamie Lokier
2009-11-18 17:33     ` Arnd Bergmann
2009-11-18 18:00       ` Alan Cox
2009-11-18 18:06         ` Arnd Bergmann
2009-11-18 18:14       ` Alan Cox
2009-11-18 19:17         ` Arnd Bergmann
2009-11-18 17:35     ` Oliver Neukum
2009-11-18 17:50       ` Jamie Lokier
2009-11-18 18:16         ` Alan Cox
2009-11-19  2:40           ` Jamie Lokier
2009-11-19 10:13             ` Alan Cox
2009-11-18 17:55       ` Alan Cox
2009-11-18 17:55       ` Jan Blunck [this message]
2009-11-18 17:53   ` Jan Blunck
2009-11-18 18:17     ` Alan Cox
2009-11-18 20:02       ` Jan Blunck

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