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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B688DC636CD for ; Mon, 30 Jan 2023 20:55:57 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pMbBb-0005Bv-T5; Mon, 30 Jan 2023 15:55:31 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pMbBZ-0005B9-Rb for qemu-devel@nongnu.org; Mon, 30 Jan 2023 15:55:29 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pMbBX-0004YZ-Vy for qemu-devel@nongnu.org; Mon, 30 Jan 2023 15:55:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675112126; 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; bh=i9ey6zaqZTEFee96Dm6zUthwDaYWO7nRpUjJ9HToa/0=; b=YpqksHh1veKs29RDYJXrFFmA/3/2n1HutjujJqfVeNpMRJatv7xs4uSxMUJVTLNjiY+oXw tzoZxE87YzsrbjgtWNtuWYLahaBniRvHIDXiJoFrWz9UF5Nvdn2LzCj9THuCdha5Z7PM1v qAfC/xIrZQlS0qUazmSrztaN6QH8YaU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-424-tMd2hKSFODuwkS3Tp-89ew-1; Mon, 30 Jan 2023 15:55:22 -0500 X-MC-Unique: tMd2hKSFODuwkS3Tp-89ew-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 717EA8030D5; Mon, 30 Jan 2023 20:55:22 +0000 (UTC) Received: from localhost (unknown [10.39.195.80]) by smtp.corp.redhat.com (Postfix) with ESMTP id CC5C6492B05; Mon, 30 Jan 2023 20:55:21 +0000 (UTC) Date: Mon, 30 Jan 2023 15:55:20 -0500 From: Stefan Hajnoczi To: Eric Blake Cc: qemu-devel@nongnu.org, Fam Zheng , Kevin Wolf , Hanna Reitz , qemu-block@nongnu.org, Fiona Ebner Subject: Re: [PATCH 3/4] qemu-io: add -r option to register I/O buffer Message-ID: References: <20230126201401.348845-1-stefanha@redhat.com> <20230126201401.348845-4-stefanha@redhat.com> <20230127232430.zy7x7wq2dvb3g3y2@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="SzXi//s6nGS8dt0L" Content-Disposition: inline In-Reply-To: <20230127232430.zy7x7wq2dvb3g3y2@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --SzXi//s6nGS8dt0L Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jan 27, 2023 at 05:24:30PM -0600, Eric Blake wrote: > On Thu, Jan 26, 2023 at 03:14:00PM -0500, Stefan Hajnoczi wrote: > > The blk_register_buf() API is an optimization hint that allows some > > block drivers to avoid I/O buffer housekeeping or bounce buffers. > >=20 > > Add an -r option to register the I/O buffer so that qemu-io can be used > > to test the blk_register_buf() API. The next commit will add a test that > > uses the new option. > >=20 > > Signed-off-by: Stefan Hajnoczi > > --- > > qemu-io-cmds.c | 149 ++++++++++++++++++++++++++++++++++--------------- > > 1 file changed, 103 insertions(+), 46 deletions(-) > >=20 >=20 > > static void *qemu_io_alloc_from_file(BlockBackend *blk, size_t len, > > - const char *file_name) > > + const char *file_name, bool regis= ter_buf) > > { > > char *buf, *buf_origin; > > FILE *f =3D fopen(file_name, "r"); > > @@ -414,6 +423,10 @@ static void *qemu_io_alloc_from_file(BlockBackend = *blk, size_t len, > > fclose(f); > > f =3D NULL; > > =20 > > + if (register_buf) { > > + blk_register_buf(blk, buf_origin, len, &error_abort); > > + } >=20 > Why is this conditionally true... >=20 > > + > > if (len > pattern_len) { > > len -=3D pattern_len; > > buf +=3D pattern_len; > > @@ -431,7 +444,7 @@ static void *qemu_io_alloc_from_file(BlockBackend *= blk, size_t len, > > return buf_origin; > > =20 > > error: > > - qemu_io_free(buf_origin); > > + qemu_io_free(blk, buf_origin, len, false); >=20 > ...but cleanup unconditionally false? It looks suspicious but it's correct: goto error only happens before the blk_register_buf() call. Therefore we must *not* unregister the buffer at this point. I'll add a comment to make this clear. >=20 > > @@ -719,6 +732,7 @@ static void read_help(void) > > " -p, -- ignored for backwards compatibility\n" > > " -P, -- use a pattern to verify read data\n" > > " -q, -- quiet mode, do not show I/O statistics\n" > > +" -r, -- register I/O buffer\n" > > " -s, -- start offset for pattern verification (only with -P)\n" > > " -v, -- dump buffer to standard output\n" >=20 > Here we have kept more or less alphabetical... >=20 > > @@ -909,6 +932,7 @@ static void readv_help(void) > > " -P, -- use a pattern to verify read data\n" > > " -v, -- dump buffer to standard output\n" > > " -q, -- quiet mode, do not show I/O statistics\n" > > +" -r, -- register I/O buffer\n" >=20 > ...here we have not. While it's pre-existing, would it be worth > touching up while you're here? >=20 > > @@ -1455,6 +1503,7 @@ static void aio_read_help(void) > > " -i, -- treat request as invalid, for exercising stats\n" > > " -v, -- dump buffer to standard output\n" > > " -q, -- quiet mode, do not show I/O statistics\n" > > +" -r, -- register I/O buffer\n" >=20 > Another pre-existing spot. >=20 > Overall makes sense to me. Sure, I'll order the help output alphabetically in the next revision. Stefan --SzXi//s6nGS8dt0L Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmPYLrcACgkQnKSrs4Gr c8gjZAf/ZOzyGHBgG7LRpNjgRi2ov5aDFgtkFktfPuTq6ufgSKsWsi2jP32whEu+ yRax+vQHWt8+OJKkJIJDUEPmJFLV2zwWo4SDSnNXycut/0x4br1ED5CqZdAfXfIU ZjoAtNhI09iki07jVHR55FdQfUP3096GVO2OU8AVrkPpjiPRut4RZlMB3oXAGwWX lHmfHcS151vN40EddhsVUaCetqlJzX7phyKLxt6a58N2tRVhF+HetOqqW5oVdL0y BqFrtnS6o9NLG9zML2vZocNyVVkrPT8wk/Tw/r/VSUShp01bk8NzlmTGuhut/Nhb 0MJlDBq1br49Nq5jzadcyH2kbXuJcQ== =/WnH -----END PGP SIGNATURE----- --SzXi//s6nGS8dt0L--