From patchwork Thu Aug 25 16:15:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 12955045 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 92ADFECAA25 for ; Thu, 25 Aug 2022 16:15:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240803AbiHYQP1 (ORCPT ); Thu, 25 Aug 2022 12:15:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242973AbiHYQPZ (ORCPT ); Thu, 25 Aug 2022 12:15:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C2651573A; Thu, 25 Aug 2022 09:15:23 -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 dfw.source.kernel.org (Postfix) with ESMTPS id DEA3261B7C; Thu, 25 Aug 2022 16:15:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91680C433B5; Thu, 25 Aug 2022 16:15:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1661444122; bh=u9Ghl7TkYlx4h5gPcy/Fm5vU59cOedqmjOD4pBXghVs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A/SGhxfqDYpB5hPxz6UxiRs26o01eLebUwupK8kC+Wfe4eXrDPazt/PWA21wO9gtm i99aqOcn854/pfR80H9iXYQd9TJlocti7VxnBsfc81u6Py04Dmh+lMaqGxsyehtr0x GaqCcykcCTIukviFErXZOEgCZdt4W2eEyGpemvdajzA3mJ6SzOoTiXC34y9H+xJiWe owqLy+vIw8Kw5hDA2FjYa98H8110kbsfwoTu2qAvzZ+xy4xgh4piRMrqq/PfNStXa7 BMSUKZTY9g4FezHMxcYcisXMN3XGWJZ2YxiNfuZ78qGaaqBL1YliAzueKZ6WgtBVpv D1Qke13oXPM5w== 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 1/2] xen-blkback: Advertise feature-persistent as user requested Date: Thu, 25 Aug 2022 16:15:10 +0000 Message-Id: <20220825161511.94922-2-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 blkback 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: e94c6101e151 ("xen-blkback: 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-blkback/common.h | 3 +++ drivers/block/xen-blkback/xenbus.c | 6 ++++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h index bda5c815e441..a28473470e66 100644 --- a/drivers/block/xen-blkback/common.h +++ b/drivers/block/xen-blkback/common.h @@ -226,6 +226,9 @@ struct xen_vbd { sector_t size; unsigned int flush_support:1; unsigned int discard_secure:1; + /* Connect-time cached feature_persistent parameter value */ + unsigned int feature_gnt_persistent_parm:1; + /* Persistent grants feature negotiation result */ unsigned int feature_gnt_persistent:1; unsigned int overflow_max_grants:1; }; diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index ee7ad2fb432d..c0227dfa4688 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -907,7 +907,7 @@ static void connect(struct backend_info *be) xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", - be->blkif->vbd.feature_gnt_persistent); + be->blkif->vbd.feature_gnt_persistent_parm); if (err) { xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", dev->nodename); @@ -1085,7 +1085,9 @@ static int connect_ring(struct backend_info *be) return -ENOSYS; } - blkif->vbd.feature_gnt_persistent = feature_persistent && + blkif->vbd.feature_gnt_persistent_parm = feature_persistent; + blkif->vbd.feature_gnt_persistent = + blkif->vbd.feature_gnt_persistent_parm && xenbus_read_unsigned(dev->otherend, "feature-persistent", 0); blkif->vbd.overflow_max_grants = 0;