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=-11.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,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 BA11EC433DF for ; Mon, 17 Aug 2020 16:01:47 +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 7B4CB20729 for ; Mon, 17 Aug 2020 16:01:47 +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="BobM3l/3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B4CB20729 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]:36324 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k7hZy-0008Bk-Hb for qemu-devel@archiver.kernel.org; Mon, 17 Aug 2020 12:01:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59162) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k7hM7-00015s-6m for qemu-devel@nongnu.org; Mon, 17 Aug 2020 11:47:27 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:24677 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1k7hM4-0008Ok-Re for qemu-devel@nongnu.org; Mon, 17 Aug 2020 11:47:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1597679243; 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: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=HN05WRduQCJrrui6EAIVX+942t3oRyS4MqLgr4JJZJo=; b=BobM3l/3DEP2+bdvy969rR4SsulGU1BS1Aix4RPOE0V5OAVjkCX0gjPoLKJzP/8vR+83dg yiDwmWV9bNHp3CEkTIyAFFrni9ntZNkp8rdgJmzJH1Xat49ENtgjUNIG8NxvNzNbvivYRT a28cmhW1KrgZpXti2OKyJ9EK53f5EGE= 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-221-aHe5HBGfPKeyt6VZn0-rPQ-1; Mon, 17 Aug 2020 11:47:21 -0400 X-MC-Unique: aHe5HBGfPKeyt6VZn0-rPQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DCA741DE01; Mon, 17 Aug 2020 15:47:20 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-113-146.ams2.redhat.com [10.36.113.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C7AB7756AD; Mon, 17 Aug 2020 15:47:19 +0000 (UTC) Subject: Re: [RFC PATCH 14/22] block/export: Move AioContext from NBDExport to BlockExport To: Kevin Wolf References: <20200813162935.210070-1-kwolf@redhat.com> <20200813162935.210070-15-kwolf@redhat.com> <2851aef1-176c-1b81-4941-dc4b08b6bfec@redhat.com> <20200817152259.GP11402@linux.fritz.box> From: Max Reitz Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: <95f08b8c-d2d7-aaca-0807-9361d667847d@redhat.com> Date: Mon, 17 Aug 2020 17:47:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200817152259.GP11402@linux.fritz.box> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nYnehHWijXtu6CQE09V62WHFBzLEdn4Qe" Received-SPF: pass client-ip=207.211.31.120; envelope-from=mreitz@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/17 00:24:04 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --nYnehHWijXtu6CQE09V62WHFBzLEdn4Qe Content-Type: multipart/mixed; boundary="CM4Zro4hcKlLeX8AVMaF54aztoaSK3xfe" --CM4Zro4hcKlLeX8AVMaF54aztoaSK3xfe Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 17.08.20 17:22, Kevin Wolf wrote: > Am 17.08.2020 um 16:56 hat Max Reitz geschrieben: >> On 13.08.20 18:29, Kevin Wolf wrote: >>> Signed-off-by: Kevin Wolf >>> --- >>> include/block/export.h | 6 ++++++ >>> nbd/server.c | 26 +++++++++++++------------- >>> 2 files changed, 19 insertions(+), 13 deletions(-) >> >> Reviewed-by: Max Reitz >> >>> diff --git a/include/block/export.h b/include/block/export.h >>> index f44290a4a2..5459f79469 100644 >>> --- a/include/block/export.h >>> +++ b/include/block/export.h >>> @@ -33,6 +33,12 @@ struct BlockExport { >>> * the export. >>> */ >>> int refcount; >>> + >>> + /* >>> + * The AioContex whose lock needs to be held while calling >> >> *AioContext >> >>> + * BlockExportDriver callbacks. >> >> Hm. But other blk_exp_* functions (i.e. the refcount manipulation >> functions) are fair game? >=20 > Hmm... The assumption was the ref/unref are only called from the main > thread, but maybe that's not true? So maybe blk_exp_*() shouldn't lock > the AioContext internally, but require that the lock is already held, so > that they can be called both from within the AioContext (where we don't > want to lock a second tim) and from the main context. >=20 > I also guess we need a separate mutex to protect the exports list if > unref can be called from different threads. >=20 > And probably the existing NBD server code has already the same problems > with respect to different AioContexts. >=20 >>> + */ >>> + AioContext *ctx; >>> }; >>> =20 >>> extern const BlockExportDriver blk_exp_nbd; >>> diff --git a/nbd/server.c b/nbd/server.c >>> index 2bf30bb731..b735a68429 100644 >>> --- a/nbd/server.c >>> +++ b/nbd/server.c >> >> [...] >> >>> @@ -1466,7 +1464,7 @@ static void blk_aio_attached(AioContext *ctx, voi= d *opaque) >>> =20 >>> trace_nbd_blk_aio_attached(exp->name, ctx); >>> =20 >>> - exp->ctx =3D ctx; >>> + exp->common.ctx =3D ctx; >> >> (Not sure if I=CD=84=E2=80=99m missing anything to that regard), but per= haps after >> patch 21 we can move this part to the common block export code, and >> maybe make it call a BlockExportDriver callback (that handles the rest >> of this function). >=20 > Could probably be done. Not every export driver may support switching > AioContexts, but we can make it conditional on having the callback. Good point. > So do I understand right from your comments to the series in general > that you would prefer to make this series more complete, even if that > means that it becomes quite a bit longer? I=E2=80=99m not necessarily asking for this now, I=E2=80=99m mostly asking = whether you have the same idea as me on things like this. I don=E2=80=99t mind too muc= h leaving this in an unfinished state as long as we both agree that it=E2=80= =99s kind of unfinished. Sorry if this is a bit frustrating to you because you wrote in the cover letter that indeed you are unsure about how complete you want to do this. The problem is that I don=E2=80=99t know exactly what things you=E2= =80=99re referring to, so I just point out everything that stands out to me. If you=E2=80=99re aware of those things, and we can work on them later, then t= hat=E2=80=99s OK. OTOH... Yes, from a design standpoint, I think it makes sense to pull out as much specialized code as possible from NBD into the generalized block export code. But I say that as a reviewer. You would have to do that, so I want to leave it to you how much work you think is reasonable to put into that. Leaving a couple of rough edges here and there shouldn=E2=80=99t be a problem. (Or maybe leaving something to me for when= I add fuse export code.) Max --CM4Zro4hcKlLeX8AVMaF54aztoaSK3xfe-- --nYnehHWijXtu6CQE09V62WHFBzLEdn4Qe Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl86poYACgkQ9AfbAGHV z0APSwf/bcGLb5/NAbHuMt1UPXowO1q0jCFv17j4roXgAis82rLwV1XOypM5ylQ5 FEndzowsve5STodkiUnoi90Eq76944MfaBnl2YODbgaShy8F6t5MnKIwZ+gqpf6E da+HbGlfcDBSDaEO72LH73+2fnDi+Q4gSGCKyErRI3xIc/fLPThA5uGAPgtcWOuw av3W43rXARbDWU0fOZRvGp6FkEIYxnc7MowtrWAzaHx8H/+mmN6TXpwYQz0lP5Lp bqibHW2rxIf18OSx4tzJtmTewSCw/ucoBJFm19kWQq73nQsVAnib2yQFYfDhsjSh UXVWpKLynvVFo555FPUljrdWpBfWjQ== =sLRa -----END PGP SIGNATURE----- --nYnehHWijXtu6CQE09V62WHFBzLEdn4Qe--