From patchwork Wed Mar 16 10:10:15 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 8597201 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 6DAE09F44D for ; Wed, 16 Mar 2016 10:10:56 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DF216202BE for ; Wed, 16 Mar 2016 10:10:55 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4061920225 for ; Wed, 16 Mar 2016 10:10:55 +0000 (UTC) Received: from localhost ([::1]:54305 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ag8Pm-0007OG-CZ for patchwork-qemu-devel@patchwork.kernel.org; Wed, 16 Mar 2016 06:10:54 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47037) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ag8PS-0007Ly-TF for qemu-devel@nongnu.org; Wed, 16 Mar 2016 06:10:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ag8PN-0005eA-Bo for qemu-devel@nongnu.org; Wed, 16 Mar 2016 06:10:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47781) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ag8PK-0005dA-D9; Wed, 16 Mar 2016 06:10:26 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id 0E5D046268; Wed, 16 Mar 2016 10:10:26 +0000 (UTC) Received: from fam-t430.redhat.com (vpn1-6-163.pek2.redhat.com [10.72.6.163]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u2GAAIo4010795; Wed, 16 Mar 2016 06:10:23 -0400 From: Fam Zheng To: qemu-devel@nongnu.org Date: Wed, 16 Mar 2016 18:10:15 +0800 Message-Id: <1458123018-18651-2-git-send-email-famz@redhat.com> In-Reply-To: <1458123018-18651-1-git-send-email-famz@redhat.com> References: <1458123018-18651-1-git-send-email-famz@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Kevin Wolf , qemu-block@nongnu.org, "Michael S. Tsirkin" , tubo@linux.vnet.ibm.com, Stefan Hajnoczi , cornelia.huck@de.ibm.com, pbonzini@redhat.com, borntraeger@de.ibm.com Subject: [Qemu-devel] [PATCH 1/4] block: Use drained section in bdrv_set_aio_context X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP An empty begin/end pair is almost the same as a bare bdrv_drain except the aio_poll inside is wrapped by aio_disable_external/aio_enable_external. This is safer, and is the only way to achieve quiescence in this aio_poll(), because bdrv_drained_begin/end pair cannot span across context detach/attach options, so it's not possible to do by the caller. Signed-off-by: Fam Zheng --- block.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block.c b/block.c index 59a18a3..31f4a9f 100644 --- a/block.c +++ b/block.c @@ -3747,7 +3747,9 @@ void bdrv_attach_aio_context(BlockDriverState *bs, void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) { - bdrv_drain(bs); /* ensure there are no in-flight requests */ + /* ensure there are no in-flight requests */ + bdrv_drained_begin(bs); + bdrv_drained_end(bs); bdrv_detach_aio_context(bs);