From patchwork Thu Aug 25 16:15:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 12955047 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1659AECAA28 for ; Thu, 25 Aug 2022 16:15:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242966AbiHYQPb (ORCPT ); Thu, 25 Aug 2022 12:15:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242959AbiHYQP3 (ORCPT ); Thu, 25 Aug 2022 12:15:29 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 561E7192AF; Thu, 25 Aug 2022 09:15:27 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id A5AD3CE27B1; Thu, 25 Aug 2022 16:15:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66BC6C433C1; Thu, 25 Aug 2022 16:15:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1661444124; bh=MyefAg5QMtTe9G45OGJvSLHtJDZ6Nxt+B/36e/BGodU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cGocOxtCF6njlitkxhkDCLXDSTKPiSMqazH+G1pz6yicN6AahRiMXMtEEEItK9Qps uvEEG/uCqhiG/RwFdvrNko811/8cLvyGfmpy1ojf+3AXVPH2hpliJyoO7iOxClLoBk K6O74IL6AwOcRc0FvC+xt/E9jl47eJxh+RcCeLEIN8KpOoup7KuTLNbKlHQxgsQxb8 iF3PzTnEfbM+yyKWhqi8QHd258xLUYf0ewS8f7eOBhaEzcd8fSr2AGMBvk/zP3HBWO JEJNoOAziB0la4PaewpTu4OZy6jMHBUl/q9GzmgZj9BbpKC8upnBJRDlyJHD/MOrLt 5nNKZoV2FGXrQ== From: SeongJae Park To: jgross@suse.com, roger.pau@citrix.com Cc: marmarek@invisiblethingslab.com, mheyne@amazon.de, xen-devel@lists.xenproject.org, axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, SeongJae Park , stable@vger.kernel.org Subject: [PATCH 2/2] xen-blkfront: Advertise feature-persistent as user requested Date: Thu, 25 Aug 2022 16:15:11 +0000 Message-Id: <20220825161511.94922-3-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220825161511.94922-1-sj@kernel.org> References: <20220825161511.94922-1-sj@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Commit e94c6101e151 ("xen-blkback: Apply 'feature_persistent' parameter when connect") made blkback to advertise its support of the persistent grants feature only if the user sets the 'feature_persistent' parameter of the driver and the frontend advertised its support of the feature. However, following commit 402c43ea6b34 ("xen-blkfront: Apply 'feature_persistent' parameter when connect") made the blkfront to work in the same way. That is, blkfront also advertises its support of the persistent grants feature only if the user sets the 'feature_persistent' parameter of the driver and the backend advertised its support of the feature. Hence blkback and blkfront will never advertise their support of the feature but wait until the other advertises the support, even though users set the 'feature_persistent' parameters of the drivers. As a result, the persistent grants feature is disabled always regardless of the 'feature_persistent' values[1]. The problem comes from the misuse of the semantic of the advertisement of the feature. The advertisement of the feature should means only availability of the feature not the decision for using the feature. However, current behavior is working in the wrong way. This commit fixes the issue by making the blkfront advertises its support of the feature as user requested via 'feature_persistent' parameter regardless of the otherend's support of the feature. [1] https://lore.kernel.org/xen-devel/bd818aba-4857-bc07-dc8a-e9b2f8c5f7cd@suse.com/ Fixes: 402c43ea6b34 ("xen-blkfront: Apply 'feature_persistent' parameter when connect") Cc: # 5.10.x Reported-by: Marek Marczykowski-Górecki Suggested-by: Juergen Gross Signed-off-by: SeongJae Park --- drivers/block/xen-blkfront.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 8e56e69fb4c4..dfae08115450 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -213,6 +213,9 @@ struct blkfront_info unsigned int feature_fua:1; unsigned int feature_discard:1; unsigned int feature_secdiscard:1; + /* Connect-time cached feature_persistent parameter */ + unsigned int feature_persistent_parm:1; + /* Persistent grants feature negotiation result */ unsigned int feature_persistent:1; unsigned int bounce:1; unsigned int discard_granularity; @@ -1848,7 +1851,7 @@ static int talk_to_blkback(struct xenbus_device *dev, goto abort_transaction; } err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", - info->feature_persistent); + info->feature_persistent_parm); if (err) dev_warn(&dev->dev, "writing persistent grants feature to xenbus"); @@ -2281,7 +2284,8 @@ static void blkfront_gather_backend_features(struct blkfront_info *info) if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) blkfront_setup_discard(info); - if (feature_persistent) + info->feature_persistent_parm = feature_persistent; + if (info->feature_persistent_parm) info->feature_persistent = !!xenbus_read_unsigned(info->xbdev->otherend, "feature-persistent", 0);