Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752499AbdHNORN (ORCPT ); Mon, 14 Aug 2017 10:17:13 -0400 Received: from hr2.samba.org ([144.76.82.148]:36726 "EHLO hr2.samba.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751687AbdHNORL (ORCPT ); Mon, 14 Aug 2017 10:17:11 -0400 X-Greylist: delayed 2157 seconds by postgrey-1.27 at vger.kernel.org; Mon, 14 Aug 2017 10:17:10 EDT Subject: Re: [[PATCH v1] 02/37] [CIFS] SMBD: Add structure for SMBD transport To: Long Li , Steve French , "linux-cifs@vger.kernel.org" , "samba-technical@lists.samba.org" , "linux-kernel@vger.kernel.org" , "linux-rdma@vger.kernel.org" , Christoph Hellwig References: <1501704648-20159-1-git-send-email-longli@exchange.microsoft.com> <1501704648-20159-3-git-send-email-longli@exchange.microsoft.com> <9632c208-d6a5-2c47-b583-274d046d97bd@samba.org> From: Stefan Metzmacher Openpgp: id=A3D192CE44EF412517BCED646A739B025C6B98D4 Message-ID: <61ab1564-d699-e8f2-631e-67a6c28b678b@samba.org> Date: Mon, 14 Aug 2017 15:41:04 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Wlhc6bDPnqKSkcktf1RjJqGt9MkbL6J3S" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5671 Lines: 135 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Wlhc6bDPnqKSkcktf1RjJqGt9MkbL6J3S Content-Type: multipart/mixed; boundary="npcWNCPcXEWnfKBrgGRWiExisTCAPmhwE"; protected-headers="v1" From: Stefan Metzmacher To: Long Li , Steve French , "linux-cifs@vger.kernel.org" , "samba-technical@lists.samba.org" , "linux-kernel@vger.kernel.org" , "linux-rdma@vger.kernel.org" , Christoph Hellwig Message-ID: <61ab1564-d699-e8f2-631e-67a6c28b678b@samba.org> Subject: Re: [[PATCH v1] 02/37] [CIFS] SMBD: Add structure for SMBD transport References: <1501704648-20159-1-git-send-email-longli@exchange.microsoft.com> <1501704648-20159-3-git-send-email-longli@exchange.microsoft.com> <9632c208-d6a5-2c47-b583-274d046d97bd@samba.org> In-Reply-To: --npcWNCPcXEWnfKBrgGRWiExisTCAPmhwE Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi Long, >> It seems that the new transport is tied to it's caller regarding struc= tures and >> naming conventions. >> >> I think it would be better to strictly separate them, as I'd like to u= se the >> SMBDirect transport also from the userspace for the client side e.g. i= n >> Samba's '[lib]smbclient', but also in Samba's server side code 'smbd'.= >=20 > Thank you for reviewing the patch set. >=20 > I think it is possible to separate the common code that implements the = SMBDirect transport. There are some challenges to reuse the same code for= both kernel and user spaces. > 1. Kernel mode RDMA verbs are similar but different to user-mode ones. > 2. Some RDMA features (e.g Fast Registration Work Request) are not avai= lable in user-mode. > 3. Locking and synchronization mechanism is different > 4. Memory management is different. > 5. Process creation/scheduling and data sharing between processes are d= ifferent, and there is no user-mode code running in interrupt/softirq. >=20 > Those needs to be abstracted through a layer, the rest of the code can = be shared. I can work on this after patch set is reviewed. I guess this is a misunderstanding... I don't want to use that code and run it in userspace, I have a userspace prototype more or less working here, see https://git.samba.org/?p=3Dmetze/samba/wip.git;a=3Dshortlog;h=3Drefs/head= s/master3-rdma and https://git.samba.org/?p=3Dmetze/samba/wip.git;a=3Dblob;f=3Dlibcli/smb/sm= b_direct.c;h=3D9cc0d861ccfcbb4df9ef6ad85a7fe3d262e549c0;hb=3D85d46de6fdbb= a041d3e8004af46865a72d2b8405 I goal is that we'll have an api that allows userspace code to use the kernel code SMBDirect code. This userspace code would get a file descriptor from the kernel and would be able to use it similar to a tcp socket. If the kernel would simulate the 4 byte length header, it's trivial to get to a stage were smbclient and smbd are able to support SMBDirect without much changes. We only need to replace connect(), listen(), accept() and a few more by SMBDirect versions. For the real data transfer we might be able to use memfd_create() or something similar to share the buffers between userspace and kernel. I guess this is a long way, but having the basic SMBDirect code in dependently in the kernel would help a lot. >> Would it be possible to isolate this in >> smb_direct.c and smb_direct.h while using >> smb_direct_* prefixes for structures and functions? Also avoiding the = usage >> of other headers from fs/cifs/*.h, expect for something generic like n= terr.h. >=20 > Sure I will make naming changes and clean up the header files. Thanks! >> I guess 'struct cifs_rdma_info' would then be 'struct smb_direct_conne= ction'. >> And it won't have a reference to struct TCP_Server_Info. >=20 > I will look for ways to remove reference to struct TCP_Server_Info . Th= e reason why it has a reference to TCP_Server_Info is that: TCP_Server_In= fo represents a transport connection, although it also has many other TCP= related code. SMBD needs to get to this connection TCP_Server_Info and s= et the transport status on shutdown (and maybe other situations). >=20 Wouldn't it be better to provide a way to ask for the connection state and let the caller ask for the state instead of changing the callers structure? metze --npcWNCPcXEWnfKBrgGRWiExisTCAPmhwE-- --Wlhc6bDPnqKSkcktf1RjJqGt9MkbL6J3S Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJZkahzAAoJEA219WEoab1WwEAP/2Lsf1gqk+zm/O9/7a5KMj+h 0MTYS38aD7X4G7EE3h6Z2qhbLyFEnyOHyULcBaUy3fqVep1xqpcuIc6ZW+KxvkYi 84yL8gnu+UCQFry81Cql8DRouqD8oGEvBYQ+I9Op3Tk3e8GEcqXLP9brImQNtRAJ f8ouR5JrcwnH+D/07cf3hQ3rn1j3arvoDcbFdJM3Z5hKzolyuFQO3Si7ITqwcrrQ COMHUk5UMijcXtwo1hY/oWsi/Kto+c/S+pa10H+Hotu/F6OG7mC5G9ECnpFI1p5+ 4zx0WoATxlZPVlLBHwpV1Xxx6i/orOZrUHmn5wMbKlWXyyd3iMHjihoH4zB2hwHX TYzVrIWme3M/M9QhoqkobW/Zd/FOzOuMKtRGa1w3/LGEG6R+U4vwtiKvRGjQ4k81 kqIfXZgq3x3qhTRi39rbsJr4CPpIe++neh2UjANO8t1yTmI7gJV0tk3qU6kYKGUn aTaMBCl02imliBaIRjwPRWjEpi0sscBQkY8mbyQWZK7/G8fSyT3R7S37ebonoLkR XPRk5Yz4mtE+hyjDzKakqOMsJ6d85mrxMySMqSUd5Ygqvp4drYzrv1VCtJuAmvAF lnVsBf8lX5W1sItU4hHIWvU2TQ4X4FIZgQkMk5MR6Kj3GFs1RkbeWz0f9gh/TkmX PiLJzOuizaiFQVSpi0KY =5Xey -----END PGP SIGNATURE----- --Wlhc6bDPnqKSkcktf1RjJqGt9MkbL6J3S--