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=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 62D94C433DB for ; Tue, 19 Jan 2021 10:39:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2486B2312E for ; Tue, 19 Jan 2021 10:39:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389354AbhASK2l (ORCPT ); Tue, 19 Jan 2021 05:28:41 -0500 Received: from mx2.suse.de ([195.135.220.15]:47748 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731747AbhASKMY (ORCPT ); Tue, 19 Jan 2021 05:12:24 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611051087; h=from:from:reply-to: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=JsGTkhtRuxb3Ac4Sx1XpqYNH/VVhKMi8Dm3Oi6h0IzI=; b=lgcWFVcjFOkeKZVmlSfj553CkEvLCYCD0J/1huVT/eXp4/5H20zzyC6u3mxnsvoevbLpAW qsaFdbayRX+hOtvUflhRDpE7Opn1orstZJ41uhTtRBuVqBI6SXrWxZJ9JOQoRkyW+wuC1R YfgF/5P7aQIXp6YDB4j1lGh9Oqho070= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 0EE9BACAC; Tue, 19 Jan 2021 10:11:27 +0000 (UTC) Subject: Re: [PATCH] xen-blkfront: don't make discard-alignment mandatory To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: linux-kernel@vger.kernel.org, Arthur Borsboom , Boris Ostrovsky , Stefano Stabellini , Konrad Rzeszutek Wilk , Jens Axboe , xen-devel@lists.xenproject.org, linux-block@vger.kernel.org References: <20210118151528.81668-1-roger.pau@citrix.com> <7cef385d-efe3-2661-bee2-9d21f159a5fb@suse.com> <20210119100651.afyccratx6ha52kc@Air-de-Roger> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <20969962-331d-50d9-dc65-772b564ab1c6@suse.com> Date: Tue, 19 Jan 2021 11:11:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210119100651.afyccratx6ha52kc@Air-de-Roger> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ylEqUBRZNTFs0WBSkCXClikBiPWK8t7Ny" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --ylEqUBRZNTFs0WBSkCXClikBiPWK8t7Ny Content-Type: multipart/mixed; boundary="UgLdTB1bgFg08HjZtFhPNLleFdwEFI4mE"; protected-headers="v1" From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: linux-kernel@vger.kernel.org, Arthur Borsboom , Boris Ostrovsky , Stefano Stabellini , Konrad Rzeszutek Wilk , Jens Axboe , xen-devel@lists.xenproject.org, linux-block@vger.kernel.org Message-ID: <20969962-331d-50d9-dc65-772b564ab1c6@suse.com> Subject: Re: [PATCH] xen-blkfront: don't make discard-alignment mandatory References: <20210118151528.81668-1-roger.pau@citrix.com> <7cef385d-efe3-2661-bee2-9d21f159a5fb@suse.com> <20210119100651.afyccratx6ha52kc@Air-de-Roger> In-Reply-To: <20210119100651.afyccratx6ha52kc@Air-de-Roger> --UgLdTB1bgFg08HjZtFhPNLleFdwEFI4mE Content-Type: multipart/mixed; boundary="------------D45C3EBEC939FF19C0556E34" Content-Language: en-US This is a multi-part message in MIME format. --------------D45C3EBEC939FF19C0556E34 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 19.01.21 11:06, Roger Pau Monn=C3=A9 wrote: > On Tue, Jan 19, 2021 at 08:43:01AM +0100, J=C3=BCrgen Gro=C3=9F wrote: >> On 18.01.21 16:15, Roger Pau Monne wrote: >>> Don't require the discard-alignment xenstore node to be present in >>> order to correctly setup the feature. This can happen with versions o= f >>> QEMU that only write the discard-granularity but not the >>> discard-alignment node. >>> >>> Assume discard-alignment is 0 if not present. While there also fix th= e >>> logic to not enable the discard feature if discard-granularity is not= >>> present. >>> >>> Reported-by: Arthur Borsboom >>> Signed-off-by: Roger Pau Monn=C3=A9 >>> --- >>> Cc: Boris Ostrovsky >>> Cc: Juergen Gross >>> Cc: Stefano Stabellini >>> Cc: Konrad Rzeszutek Wilk >>> Cc: "Roger Pau Monn=C3=A9" >>> Cc: Jens Axboe >>> Cc: xen-devel@lists.xenproject.org >>> Cc: linux-block@vger.kernel.org >>> Cc: Arthur Borsboom >>> --- >>> drivers/block/xen-blkfront.c | 25 +++++++++++++------------ >>> 1 file changed, 13 insertions(+), 12 deletions(-) >>> >>> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfron= t.c >>> index 5265975b3fba..5a93f7cc2939 100644 >>> --- a/drivers/block/xen-blkfront.c >>> +++ b/drivers/block/xen-blkfront.c >>> @@ -2179,22 +2179,23 @@ static void blkfront_closing(struct blkfront_= info *info) >>> static void blkfront_setup_discard(struct blkfront_info *info) >>> { >>> - int err; >>> - unsigned int discard_granularity; >>> - unsigned int discard_alignment; >>> + unsigned int discard_granularity =3D 0; >>> + unsigned int discard_alignment =3D 0; >>> + unsigned int discard_secure =3D 0; >>> - info->feature_discard =3D 1; >>> - err =3D xenbus_gather(XBT_NIL, info->xbdev->otherend, >>> + xenbus_gather(XBT_NIL, info->xbdev->otherend, >>> "discard-granularity", "%u", &discard_granularity, >>> "discard-alignment", "%u", &discard_alignment, >>> + "discard-secure", "%u", &discard_secure, >>> NULL); >> >> This would mean that "discard-secure" will be evaluated only if the >> other two items are set in Xenstore. From blkif.h I can't see this is >> required, and your patch is modifying today's behavior in this regard.= >> >> You might want to have three xenbus_read_unsigned() calls instead. >=20 > You are right, discard-secure should be fetched regardless of whether > discard-alignment exists. >=20 > I can fetch discard-granularity and discard-alignment using > xenbus_gather and keep discard-secure using xenbus_read_unsigned. Let > me send a new version. I'm still not convinced this is correct. blkif.h doesn't mention that discard-alignment will be valid only with discard-granularity being present. 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