Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Jeff Layton <jlayton@kernel.org>
CC:     Neil Brown <neilb@suse.de>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v2 0/2] nfsd: close potential race between open and
 delegation
Thread-Topic: [PATCH v2 0/2] nfsd: close potential race between open and
 delegation
Thread-Index: AQHYmHlSxd5rdSP4vkm5nlP8AEo5x61/xGyA
Date:   Fri, 15 Jul 2022 18:42:52 +0000
Message-ID: <6F1AD05A-B3C7-4B2E-84CA-D08BF1093F82@oracle.com>
References: <20220715183257.41129-1-jlayton@kernel.org>
In-Reply-To: <20220715183257.41129-1-jlayton@kernel.org>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?6Lee1rSFzZuMpKbrgCD8PIL4DIWwxMHZXL+d+xwTI5falAoEhHfsa9Va6iWV?=
 =?us-ascii?Q?FM+QGOeJ4BKGtxQfA0OqfQKxfGO9WvBABgBUy/bLw0ovbhEkl3zGp7T4XO/x?=
 =?us-ascii?Q?QI3TVAb/lZ2GlixNIiHeAm0OMeuJzQDLCu3pvYb+UedoSmJJ2cnG6mR8ZOkD?=
 =?us-ascii?Q?3FHsJLtdAuuTGbKZsXtXELvBh5Netp7G+T54efg74V887SZZzEJnSwYb96hY?=
 =?us-ascii?Q?aWGmTtB0DTN2EooGx/Q1GVunEwQiFdgG9QpLLelysgnCVtIL3w9jJP7CzBMy?=
 =?us-ascii?Q?KJW9q3a6Zat/Cv08lWqkg5G58iQQ3/t3xI2+NAc5RdPAU52/Pb8W/WEzjwwk?=
 =?us-ascii?Q?EqJmVTSJF+lBzdOGMADAmKReK1yUtZj5SQ7xZYIXYophTb+Bsqgl30h2IC5m?=
 =?us-ascii?Q?0ttWcQ4FJCNQ1Sp3AgDUml9Ty5MX3fqo9rJ1dRcLzjkEV24SWipC+mVSvDHz?=
 =?us-ascii?Q?NAQyt1+iaP0YkBilLW84bp0Xl4H9Xz/ZAwzQXrBSaF3unuiarJ4jLXnlsP2e?=
 =?us-ascii?Q?xOizLyEjkQTna4WFwlqZMVbT4mRZWY0jH90aXO4Aj8ILwgVk4i+Hc73CuOQ/?=
 =?us-ascii?Q?uQQ8tszaPdgQ9U1qHMYQ78hIFTpRZBAUMUBlX5XH8DAPxEI4/6s+p0ttUpAC?=
 =?us-ascii?Q?SzQGNvr8VjcYudsDjdosMRE/kQpUGptqmVpuoXO1/9cNpVkZo60k6TrpiV9w?=
 =?us-ascii?Q?BkGgWs6BbPyjqCq8WnIL3/9OHpNCs9ec45CpmTvQ7GSB8jIiI2Z24ylz8Thr?=
 =?us-ascii?Q?uWNu4axKTPxsd76iWrQwAs+50zn1XiECiwblxxYl9gTgFJckasbXPdYUjEb7?=
 =?us-ascii?Q?NkLjPrurgPVsAp6CFqk8wgctWLT1XoHAeAGLGrATakusRkolKi26ZNfHo3Jt?=
 =?us-ascii?Q?IjRybdX4XdlDS3dOAOc9Vvgp2EMGIcDoSZxHpSNAq+Yb3JOFbF57PI3C8w5q?=
 =?us-ascii?Q?Zk8fhx6pvXuv77iEJRc28wtz6ZA6ZN8pXBuxs/4BuU/Fv7bRUxKTS+/yW4qJ?=
 =?us-ascii?Q?focN4fylypyh/ko7y3/OPpPzoIOCeiXQWBpw5564BwMf65lV91CRhmZNETvf?=
 =?us-ascii?Q?kko3OI2ZGJKLAUEeSBsNUWeW17SWMmcStAE1arMKO6ftrDhbwPjxi4G+if7o?=
 =?us-ascii?Q?NoePELBsHRHIDa1y86ZivtLVeXBxdvI4AarYdtT6VZYqpWVy2LWaOt32u8dO?=
 =?us-ascii?Q?uMO0JEgYcYKVPvK+VumcAnh0XAp14lj1PWDKc7traASxm10G/ASLn8Ud1GBt?=
 =?us-ascii?Q?xvapI9Z2iscGrF3bxneb87DGNUqA1bXpz2aplvkyzMnrb91qwVtoecURTrv8?=
 =?us-ascii?Q?VBYx5/8vb7uIDwlum1vRgsblXVAw8zbQoxJo/gaAPs9QNhpuE368dwJqThp5?=
 =?us-ascii?Q?qDQsnFmWJXyBmbtlkWEOIM4+0vP5Xn8qL5S3Qkys5YjXpPdfSghshQFlKNaF?=
 =?us-ascii?Q?PwlKFneb8B4r3RCQvR2X6H7JR6UkraEyQ4p0uyb+Oy6+my1VPkCKCoMYAYil?=
 =?us-ascii?Q?sbGFUWlBSKpQ1w+wEmMrcJM1IUX46Q1Lm2xsgai5ABGNex3U6B/RMqZgbWuC?=
 =?us-ascii?Q?2cTBH9VK/wXLOwiYeyJBt6WXrpsYjU8JqzJEnv23VWFpnyy8q99Z2A+nERVC?=
 =?us-ascii?Q?bg=3D=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-ID: <8BCE0C4D65F6D84783BE108017282355@namprd10.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: BN0PR10MB5128.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 2feda990-8916-4d1f-a3ad-08da6691d2f6
X-MS-Exchange-CrossTenant-originalarrivaltime: 15 Jul 2022 18:42:52.1548
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: udcxAkps5XnwkKSnA/JgH+vBSy9hRjwepbdsQMsXCA3pc9EBzBpMSL9DL6GVkth4k/q4Yk2SJQwHtnFqLmqiRA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR1001MB2053
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.517,18.0.883
 definitions=2022-07-15_10:2022-07-14,2022-07-15 signatures=0
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 phishscore=0
 suspectscore=0 mlxlogscore=861 mlxscore=0 spamscore=0 malwarescore=0
 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2206140000 definitions=main-2207150083
X-Proofpoint-GUID: 5QG7Z7vCVf9lwS9m07AeBmhDOx4TwLO3
X-Proofpoint-ORIG-GUID: 5QG7Z7vCVf9lwS9m07AeBmhDOx4TwLO3
X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-nfs.vger.kernel.org>
X-Mailing-List: linux-nfs@vger.kernel.org


> On Jul 15, 2022, at 2:32 PM, Jeff Layton <jlayton@kernel.org> wrote:
>=20
> v2:
> - use nfsd_lookup_dentry instead of lookup_one_len
>=20
> Here's a respin of the patches to fix up the potential race between an
> open and delegation. I took Neil's advice an changed over to use
> nfsd_lookup_dentry.
>=20
> This patchset is based on top of Neil's recent patchset entitled:
>=20
>    [PATCH 0/8] NFSD: clean up locking.

Thanks to both of you for pursuing this work! I think there are
some good improvements here.

Note that there are some outstanding review comments (aside from
the disagreement about how to refactor nfsd_create) so I expect
Neil will be reposting his series. This is just to note that, as
long as your series is based on his, I will consider your series
as RFC until his base series is stable and pulled.

I'll review again today or over the weekend.


> Tested with xfstests and it seemed to behave. I haven't done any testing
> to ensure that the race is actually fixed, mainly because I don't have a
> way to reliably reproduce it.

That's the thing: we don't have many tests that use multiple clients
targeting the same set of files.


> Jeff Layton (2):
>  nfsd: drop fh argument from alloc_init_deleg
>  nfsd: vet the opened dentry after setting a delegation
>=20
> fs/nfsd/nfs4state.c | 58 ++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 49 insertions(+), 9 deletions(-)
>=20
> --=20
> 2.36.1
>=20

--
Chuck Lever