From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Jamie Lokier <jamie@shareable.org>
Cc: "Oliver Neukum" <oliver@neukum.org>,
"Jan Blunck" <jblunck@suse.de>,
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: Thu, 19 Nov 2009 10:13:30 +0000 [thread overview]
Message-ID: <20091119101330.5a09d6b0@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <20091119024008.GB15128@shareable.org>
> That was implicit in my question: Are there any seekable devices where
> bytes read != offset delta, and if yes, is that correct behaviour, a
> bug, or a silly interface that should go away?
It's neither a bug nor silly, although some of our users of it are a bit
strange.
Consider a block based device. It makes complete sense then that a short
read (eg user space passing a small buffer) causes the seek position to
move on one block. Ditto a block based system with EOF markers might do
that (eg some tape systems).
In the weirdness (but API) category we have things like the MSR driver
which returns an entire MSR for each byte offset.
Alan
next prev parent reply other threads:[~2009-11-19 10:12 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 [this message]
2009-11-18 17:55 ` Alan Cox
2009-11-18 17:55 ` Jan Blunck
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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