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Sun, 29 Mar 2020 18:08:31 +0000 From: Chaitanya Kulkarni To: "hch@infradead.org" , Bart Van Assche CC: Jack Wang , "linux-block@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "axboe@kernel.dk" , "sagi@grimberg.me" , "leon@kernel.org" , "dledford@redhat.com" , "jgg@ziepe.ca" , "danil.kipnis@cloud.ionos.com" , "rpenyaev@suse.de" , "pankaj.gupta@cloud.ionos.com" Subject: Re: [PATCH v11 15/26] block: reexport bio_map_kern Thread-Topic: [PATCH v11 15/26] block: reexport bio_map_kern Thread-Index: AQHV/rGKCEGMgRuVP0mTYK+YBVb5SA== Date: Sun, 29 Mar 2020 18:08:31 +0000 Message-ID: References: <20200320121657.1165-1-jinpu.wang@cloud.ionos.com> <20200320121657.1165-16-jinpu.wang@cloud.ionos.com> <15f25902-1f5a-a542-a311-c1e86330834b@acm.org> <20200328082953.GB16355@infradead.org> <20200329150524.GA13909@infradead.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Chaitanya.Kulkarni@wdc.com; x-originating-ip: [199.255.45.62] x-ms-publictraffictype: Email x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: a7d413d6-a7b8-4c0e-9fbe-08d7d40c30c1 x-ms-traffictypediagnostic: BYAPR04MB6232: x-ld-processed: b61c8803-16f3-4c35-9b17-6f65f441df86,ExtAddr x-microsoft-antispam-prvs: wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:7219; x-forefront-prvs: 035748864E x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR04MB4965.namprd04.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(10019020)(4636009)(136003)(376002)(396003)(366004)(346002)(39860400002)(26005)(110136005)(316002)(478600001)(54906003)(4326008)(186003)(81166006)(7696005)(81156014)(66446008)(7416002)(53546011)(8676002)(86362001)(66476007)(2906002)(66946007)(66556008)(71200400001)(9686003)(6506007)(5660300002)(55016002)(76116006)(52536014)(8936002)(33656002)(64756008);DIR:OUT;SFP:1102; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: WTmES70+9XH/y5k4KDy+K1Rkx89+aNL4GSEYl8AZJcR0q3qoKn8MFq/rrKrA2evphWhurl2OpZpVb2C7Qn4Q4AlsX14MM1YhRoyKCMHcW5RvgCW7aBe1pNy9rWRu7bLmP8gNFVA/XBseSCA6yXiFWlUoFLDNd6Tmqbl39KI+We56mUYix8Y65fa+q1Nq/laNb+Ug1XthRZyC7KMirHkFXb9uqQLdpGiezexvkj7neVfgh8UJ8cvgLNbO57Aiz6L67CbHhfYHOlkrPYRIPVPusg0dMjm9utGIvtJ1Tf7I91rsAZT18zPzQenuOEvkIzortedvcZPlzYeNG80IwWxPU1aWksaqLXcbbcXnf1ReMvU3WOUe7eUJ1s+8mupCIMUlXV3ZiUUR/VZ740fTUxtAH0JAL3TExmkmny6eDSYb3g06UCDUn9Pz1NFKHbVcaCf4 x-ms-exchange-antispam-messagedata: EgkwIOBc1AuvZXSVt3pLrPOzGcJT3yCLHhp/Qx9F1SheZTki/gkH3iNNlDvnQY28Jd4Ga7+2Lh6z9VqZp8oMWUFEiNt8JlMIylJMtRiSXAeUmtRFcgZSgp7LWgSrus5GaZMjDUHO9Ff1bf6K7/DoTg== x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-Network-Message-Id: a7d413d6-a7b8-4c0e-9fbe-08d7d40c30c1 X-MS-Exchange-CrossTenant-originalarrivaltime: 29 Mar 2020 18:08:31.7607 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: YLqjA4CPZMjyFazXe6IYA8yiOrTJ7U+0EyD7RXir/8Z3PdK8lLKcVKAV0bvZCURul723oXLOZmBizLf3dU+vaXki3y2e/JZih+GfyqlUfVk= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR04MB6232 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 03/29/2020 08:05 AM, Christoph Hellwig wrote:=0A= > On Sat, Mar 28, 2020 at 09:16:55AM -0700, Bart Van Assche wrote:=0A= >> >There are more users in the Linux kernel of bio_add_pc_page() than only= =0A= >> >bio_map_kern(), e.g. the SCSI target pass-through code=0A= >> >(drivers/target/target_core_pscsi.c). The code that uses bio_map_kern()= =0A= >> >is in patch 22/26: "block/rnbd: server: functionality for IO submission= =0A= >> >to file or block dev". Isn't that use case similar to the SCSI=0A= >> >pass-through code? I think the RNBD server code also implements storage= =0A= >> >target functionality.=0A= > No, it is not at all. The RNBD case submits normal read/write bios, for= =0A= > which bio_map_kerl is the wrong interfac given that it=0A= > uses bio_add_pc_page. Read, write and other non-passthrough requests=0A= > must use bio_add_page instead.=0A= >=0A= =0A= Since rw are most common operations, it'd be nice to have a helper=0A= function for REQ_OP_[READ|WRITE] to map and submit bio from data buffer=0A= with chaining to avoid code duplication in each driver which based on =0A= the bio_add_page().=0A= =0A= I'd be happy to send a patch for that if that is acceptable.=0A=