From nobody Wed Nov 5 18:34:00 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 153623970853445.309263484618555; Thu, 6 Sep 2018 06:15:08 -0700 (PDT) Received: from localhost ([::1]:33257 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxu7n-0002SA-Il for importer@patchew.org; Thu, 06 Sep 2018 09:15:07 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53786) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxtw2-0006mi-Hz for qemu-devel@nongnu.org; Thu, 06 Sep 2018 09:03:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fxtvr-0000tD-DD for qemu-devel@nongnu.org; Thu, 06 Sep 2018 09:02:58 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:38494 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fxtvk-0000jH-9c; Thu, 06 Sep 2018 09:02:40 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E6229402277F; Thu, 6 Sep 2018 13:02:39 +0000 (UTC) Received: from probe.redhat.com (ovpn-122-198.rdu2.redhat.com [10.10.122.198]) by smtp.corp.redhat.com (Postfix) with ESMTP id 76AA710F1BE9; Thu, 6 Sep 2018 13:02:39 +0000 (UTC) From: John Snow To: qemu-block@nongnu.org, qemu-devel@nongnu.org Date: Thu, 6 Sep 2018 09:02:25 -0400 Message-Id: <20180906130225.5118-17-jsnow@redhat.com> In-Reply-To: <20180906130225.5118-1-jsnow@redhat.com> References: <20180906130225.5118-1-jsnow@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Thu, 06 Sep 2018 13:02:39 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Thu, 06 Sep 2018 13:02:39 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jsnow@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH v5 16/16] blockdev: document transactional shortcomings X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , John Snow , Jeff Cody , Markus Armbruster , "Dr. David Alan Gilbert" , jtc@redhat.com, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RDMRC_1 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Presently only the backup job really guarantees what one would consider transactional semantics. To guard against someone helpfully adding them in the future, document that there are shortcomings in the model that would need to be audited at that time. Signed-off-by: John Snow --- blockdev.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/blockdev.c b/blockdev.c index 0cf8febe6c..d4b42403df 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2182,7 +2182,13 @@ static const BlkActionOps actions[] =3D { .instance_size =3D sizeof(BlockDirtyBitmapState), .prepare =3D block_dirty_bitmap_disable_prepare, .abort =3D block_dirty_bitmap_disable_abort, - } + }, + /* Where are transactions for MIRROR, COMMIT and STREAM? + * Although these blockjobs use transaction callbacks like the backup = job, + * these jobs do not necessarily adhere to transaction semantics. + * These jobs may not fully undo all of their actions on abort, nor do= they + * necessarily work in transactions with more than one job in them. + */ }; =20 /** --=20 2.14.4