Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:43201 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751219AbdBXSjC (ORCPT ); Fri, 24 Feb 2017 13:39:02 -0500 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: [PATCH v2 0/4] nfs/nfsd/sunrpc: enforce NFSv4 transport requirements From: Chuck Lever In-Reply-To: <20170224182525.10390-1-jlayton@redhat.com> Date: Fri, 24 Feb 2017 10:38:32 -0800 Cc: "J. Bruce Fields" , Trond Myklebust , Anna Schumaker , Linux NFS Mailing List , Tom Talpey , jgunthorpe@obsidianresearch.com Message-Id: References: <20170223170337.10686-1-jlayton@redhat.com> <20170224182525.10390-1-jlayton@redhat.com> To: Jeff Layton Sender: linux-nfs-owner@vger.kernel.org List-ID: > On Feb 24, 2017, at 10:25 AM, Jeff Layton wrote: > > v2: comment clarifications, and commit log cleanup. No functional changes. > > RFC5661 says: > > NFSv4.1 works over Remote Direct Memory Access (RDMA) and non-RDMA- > based transports with the following attributes: > > > o The transport supports reliable delivery of data, which NFSv4.1 > requires but neither NFSv4.1 nor RPC has facilities for ensuring > [34]. > > o The transport delivers data in the order it was sent. Ordered > delivery simplifies detection of transmit errors, and simplifies > the sending of arbitrary sized requests and responses via the > record marking protocol [3]. > > ...and then some hand-wavy stuff about congestion control. RFC7530 > doesn't mention needing reliable and ordered delivery, but it does need > congestion control. > > In practical terms, that means we should be excluding NFSv4 from UDP > transports. The NFS server has never enforced this requirement, > however, so a user could issue NFSv4 calls against the server via UDP. RPC-over-RDMA Version One requires the use of RDMA Reliable Connections, which is a layer above the link layer that provides reliable, in-order delivery using connection semantics. This meets all stated transport requirements in RFC 5661. The language of RFC 5661 says that UDP by itself must not be used for NFSv4. IMO the use of Reliable Connections with RPC-over-RDMA makes this a non-issue for NFSv4, even for RoCE v2. rfc5667bis-06 was submitted this morning to address this. > This patchset adds a small bit of infrastructure to the sunrpc layer to > enforce this requirement, and has the nfs and nfsd layers set the > appropriate flags for it on their server-side transports. It also has > the rpcbind client skip registering the protocol version on a UDP port > when that flag is set. > > Lightly tested by hand, but it's fairly straightforward. > > Jeff Layton (4): > sunrpc: turn bitfield flags in svc_version into bools > sunrpc: flag transports as having both reliable and ordered delivery, > and congestion control > nfs/nfsd/sunrpc: enforce transport requirements for NFSv4 > sunrpc: don't register UDP port with rpcbind when version needs > congestion control > > fs/nfs/callback_xdr.c | 6 ++++-- > fs/nfsd/nfs2acl.c | 1 - > fs/nfsd/nfs3acl.c | 1 - > fs/nfsd/nfs4proc.c | 13 +++++++------ > include/linux/sunrpc/svc.h | 12 ++++++++---- > include/linux/sunrpc/svc_xprt.h | 1 + > net/sunrpc/svc.c | 23 ++++++++++++++++++++++- > net/sunrpc/svcsock.c | 1 + > net/sunrpc/xprtrdma/svc_rdma_transport.c | 8 ++++++++ > 9 files changed, 51 insertions(+), 15 deletions(-) > > -- > 2.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever