From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:46827)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QmPqt-0001Fj-MS
	for qemu-devel@nongnu.org; Thu, 28 Jul 2011 08:38:12 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QmPqs-0000xY-QT
	for qemu-devel@nongnu.org; Thu, 28 Jul 2011 08:38:11 -0400
Received: from mx1.redhat.com ([209.132.183.28]:56324)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QmPqs-0000xM-I5
	for qemu-devel@nongnu.org; Thu, 28 Jul 2011 08:38:10 -0400
Message-ID: <4E3158DE.2010404@redhat.com>
Date: Thu, 28 Jul 2011 14:41:02 +0200
From: Kevin Wolf <kwolf@redhat.com>
MIME-Version: 1.0
References: <1311791126-11383-1-git-send-email-freddy77@gmail.com>
	<1311791126-11383-2-git-send-email-freddy77@gmail.com>
	<20110727183122.GA14736@lst.de>
	<77083DC7-E37C-4B44-9A59-DB19E34D20E2@gmail.com>
	<20110727195718.GA16212@lst.de> <4E3113F9.9090902@redhat.com>
	<20110728121556.GA17125@lst.de>
In-Reply-To: <20110728121556.GA17125@lst.de>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 1/2] linux aio: support flush operation
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Christoph Hellwig <hch@lst.de>
Cc: Frediano Ziglio <freddy77@gmail.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

Am 28.07.2011 14:15, schrieb Christoph Hellwig:
>> Christoph, on another note: Can we rely on Linux AIO never returning
>> short writes except on EOF? Currently we return -EINVAL in this case, so

"short reads" I meant, of course.

>> I hope it's true or we wouldn't return the correct error code.
> 
> More or less.  There's one corner case for all Linux I/O, and that is
> only writes up to INT_MAX are supported, and larger writes (and reads)
> get truncated to it.  It's pretty nasty, but Linux has been vocally
> opposed to fixing this issue.

I think we can safely ignore this. So just replacing the current
ret = -EINVAL; by a memset(buf + ret, 0, len - ret); ret = 0; should be
okay, right? (Of course using the qiov versions, but you get the idea)

Kevin