From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:52455)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1X2ebL-0007jp-RO
	for qemu-devel@nongnu.org; Thu, 03 Jul 2014 06:50:57 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1X2ebF-0006Sa-Mr
	for qemu-devel@nongnu.org; Thu, 03 Jul 2014 06:50:51 -0400
Received: from mx1.redhat.com ([209.132.183.28]:58033)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1X2ebF-0006SW-EF
	for qemu-devel@nongnu.org; Thu, 03 Jul 2014 06:50:45 -0400
Message-ID: <53B5357A.5030001@redhat.com>
Date: Thu, 03 Jul 2014 12:50:34 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1404303528-7115-1-git-send-email-ming.lei@canonical.com>	<1404303528-7115-3-git-send-email-ming.lei@canonical.com>	<20140703094009.GC4322@noname.redhat.com>	<CACVXFVMAXs6FK3Vz0bKJJ-to8M68dN_5n5KTWfadOhKfP+JfQg@mail.gmail.com>	<53B52ACA.4000900@redhat.com>
	<CACVXFVM1H8unfZSyt4RXFKTnv5mHo4N-1sScFnbm5Yc-qFD=gA@mail.gmail.com>
In-Reply-To: <CACVXFVM1H8unfZSyt4RXFKTnv5mHo4N-1sScFnbm5Yc-qFD=gA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v4 2/3] linux-aio: implement io plug,
 unplug and flush io queue
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: Ming Lei <ming.lei@canonical.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Fam Zheng <famz@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@redhat.com>

Il 03/07/2014 12:45, Ming Lei ha scritto:
> I think it may be needed:
>
> - following requests coming inside handle_notify():
>          req0, req1, req2-flush, req3
> - both req0 and req1 queued
> - start to handle req2-flush
> - bdrv_co_flush() calls bdrv_co_flush(bs->file), which finally
> call raw_aio_flush() to send command, but the 1st two requests
> should have been submitted to fs before the flush action

No, bdrv_aio_flush is only guaranteed to flush requests that _completed_ 
before it was sent.

Since we haven't yet told the guest that req0 and req1 are complete, 
there is no need to submit them before req2-flush.

Paolo