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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 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @kernel.org) X-ZM-MESSAGEID: 1661444174161100002 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 whe= n connect") Cc: # 5.10.x Reported-by: Marek Marczykowski-G=C3=B3recki Suggested-by: Juergen Gross Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross --- 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); =20 err =3D 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; } =20 - blkif->vbd.feature_gnt_persistent =3D feature_persistent && + blkif->vbd.feature_gnt_persistent_parm =3D feature_persistent; + blkif->vbd.feature_gnt_persistent =3D + blkif->vbd.feature_gnt_persistent_parm && xenbus_read_unsigned(dev->otherend, "feature-persistent", 0); =20 blkif->vbd.overflow_max_grants =3D 0; --=20 2.25.1 From nobody Tue May 21 07:32:54 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; 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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 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @kernel.org) X-ZM-MESSAGEID: 1661444176075100005 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 wh= en connect") Cc: # 5.10.x Reported-by: Marek Marczykowski-G=C3=B3recki Suggested-by: Juergen Gross Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross --- 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 =3D 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 b= lkfront_info *info) if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) blkfront_setup_discard(info); =20 - if (feature_persistent) + info->feature_persistent_parm =3D feature_persistent; + if (info->feature_persistent_parm) info->feature_persistent =3D !!xenbus_read_unsigned(info->xbdev->otherend, "feature-persistent", 0); --=20 2.25.1