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Lunev" , Cyrill Gorcunov , Konstantin Khorenko Subject: Re: [PATCH] nfs: block notification on fs with its own ->lock Thread-Topic: [PATCH] nfs: block notification on fs with its own ->lock Thread-Index: AQHX8qE3BtED6z/nR0SluAIrWY7pQaw2PNyAgACfSgA= Date: Fri, 17 Dec 2021 16:11:11 +0000 Message-ID: <0C441CAE-06B6-4CC0-8A52-88957DCF76EF@oracle.com> References: <20211216172013.GA13418@fieldses.org> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3654.120.0.1.13) x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 9a069ec9-2e60-4b13-4285-08d9c177d7a9 x-ms-traffictypediagnostic: CH0PR10MB4937:EE_ x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:8882; x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: 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 x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH0PR10MB4858.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(366004)(6506007)(6512007)(186003)(53546011)(2616005)(5660300002)(76116006)(15650500001)(8676002)(2906002)(122000001)(33656002)(26005)(36756003)(66946007)(508600001)(66476007)(6486002)(83380400001)(38100700002)(110136005)(86362001)(4326008)(71200400001)(66446008)(66556008)(38070700005)(8936002)(64756008)(316002)(54906003)(45980500001);DIR:OUT;SFP:1101; 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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: CH0PR10MB4858.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9a069ec9-2e60-4b13-4285-08d9c177d7a9 X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Dec 2021 16:11:11.2630 (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: CnlSs2S48vZw20W7/S9NwAs36DS9a4tAZZW4xy4uBW1+BciVBO/E90yafGSrZKkAVAT5XDOHOhvvu0MUCl8FrA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR10MB4937 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10201 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=978 phishscore=0 spamscore=0 mlxscore=0 adultscore=0 bulkscore=0 suspectscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112170093 X-Proofpoint-ORIG-GUID: OefK69Sn4_cqpeiZjAOh-sJPjhwrfpGK X-Proofpoint-GUID: OefK69Sn4_cqpeiZjAOh-sJPjhwrfpGK Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org > On Dec 17, 2021, at 1:41 AM, Vasily Averin wrote: >=20 > On 16.12.2021 20:20, J. Bruce Fields wrote: >> From: "J. Bruce Fields" >>=20 >> NFSv4.1 supports an optional lock notification feature which notifies >> the client when a lock comes available. (Normally NFSv4 clients just >> poll for locks if necessary.) To make that work, we need to request a >> blocking lock from the filesystem. >>=20 >> We turned that off for NFS in f657f8eef3ff "nfs: don't atempt blocking >> locks on nfs reexports" because it actually blocks the nfsd thread while >> waiting for the lock. >>=20 >> Thanks to Vasily Averin for pointing out that NFS isn't the only >> filesystem with that problem. >>=20 >> Any filesystem that leaves ->lock NULL will use posix_lock_file(), which >> does the right thing. Simplest is just to assume that any filesystem >> that defines its own ->lock is not safe to request a blocking lock from. >>=20 >> So, this patch mostly reverts f657f8eef3ff and b840be2f00c0, and instead >> uses a check of ->lock (Vasily's suggestion) to decide whether to >> support blocking lock notifications on a given filesystem. Also add a >> little documentation. >>=20 >> Perhaps someday we could add back an export flag later to allow >> filesystems with "good" ->lock methods to support blocking lock >> notifications. >>=20 >> Reported-by: Vasily Averin >> Signed-off-by: J. Bruce Fields >=20 > Reviewed-by: Vasily Averin I've applied this with Vasily's R-b to for-next at git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git I also cleaned up some checkpatch nits in the patch description. It might be good for subsequent work in this area to be based on the for-next branch so we can track what is done and what is left to do. -- Chuck Lever