From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0547C43603 for ; Wed, 18 Dec 2019 16:49:41 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8726D20716 for ; Wed, 18 Dec 2019 16:49:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="PpHTgZ5C" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8726D20716 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57208 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ihcW4-0007HP-8W for qemu-devel@archiver.kernel.org; Wed, 18 Dec 2019 11:49:40 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41475) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ihcUB-0005iR-Rs for qemu-devel@nongnu.org; Wed, 18 Dec 2019 11:47:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ihcUA-0001kD-DG for qemu-devel@nongnu.org; Wed, 18 Dec 2019 11:47:43 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:49580 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ihcUA-0001gn-7M for qemu-devel@nongnu.org; Wed, 18 Dec 2019 11:47:42 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576687661; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cKmpyXCe1UvmXa8493ASsmx6keV/mkvWOQw/mH2C2HM=; b=PpHTgZ5CequrKum/1KzejEQpsNdfghX9aMmFioC+C37qJ53+dDcmTiXI5kYxO0EApKskOY 8UWlqaWFpgCq/I8vei1ReezIIZGiI6PvzSklLQX2l5cRXpqrbsHAyVVlKjyHWtXHuoqPun mZ7atKV8nSE7aIEKAhbEF1K9y5QkzDE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-222--iLtyYOiNYCj776LjtS4Zg-1; Wed, 18 Dec 2019 11:47:38 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EE1399123E; Wed, 18 Dec 2019 16:47:36 +0000 (UTC) Received: from linux.fritz.box (ovpn-116-210.ams2.redhat.com [10.36.116.210]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C5F155D9E2; Wed, 18 Dec 2019 16:47:35 +0000 (UTC) Date: Wed, 18 Dec 2019 17:47:34 +0100 From: Kevin Wolf To: Paolo Bonzini Subject: Re: [PATCH 2/3] block/io: wait for serialising requests when a request becomes serialising Message-ID: <20191218164618.GD4632@linux.fritz.box> References: <1576675026-25046-1-git-send-email-pbonzini@redhat.com> <1576675026-25046-3-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 In-Reply-To: <1576675026-25046-3-git-send-email-pbonzini@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-MC-Unique: -iLtyYOiNYCj776LjtS4Zg-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Lieven , qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 18.12.2019 um 14:17 hat Paolo Bonzini geschrieben: > Marking without waiting would not result in actual serialising behavior. > Thus, make a call bdrv_mark_request_serialising sufficient for > serialisation to happen. >=20 > Signed-off-by: Paolo Bonzini > @@ -1851,13 +1841,18 @@ bdrv_co_write_req_prepare(BdrvChild *child, int64= _t offset, uint64_t bytes, > assert(!(flags & ~BDRV_REQ_MASK)); > =20 > if (flags & BDRV_REQ_SERIALISING) { > - bdrv_mark_request_serialising(req, bdrv_get_cluster_size(bs)); > + waited =3D bdrv_mark_request_serialising(req, bdrv_get_cluster_s= ize(bs)); > + /* > + * For a misaligned request, we should have already waited > + * in bdrv_padding_rmw_read and locked out concurrent writers. Actually, bdrv_padding_rmw_read() only asserts that the request is already serialised. bdrv_mark_request_serialising() is already called by the callers of bdrv_padding_rmw_read(). > + */ > + assert(!waited || > + (req->offset =3D=3D req->overlap_offset && > + req->bytes =3D=3D req->overlap_bytes)); > + } else { > + bdrv_wait_serialising_requests(req); > } > =20 > - waited =3D bdrv_wait_serialising_requests(req); > - > - assert(!waited || !req->serialising || > - is_request_serialising_and_aligned(req)); > assert(req->overlap_offset <=3D offset); > assert(offset + bytes <=3D req->overlap_offset + req->overlap_bytes)= ; > assert(end_sector <=3D bs->total_sectors || child->perm & BLK_PERM_R= ESIZE); Other than the comment, the patch looks fine to me. Kevin