Return-Path: Received: from mail-it0-f65.google.com ([209.85.214.65]:35139 "EHLO mail-it0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751355AbdAWVCG (ORCPT ); Mon, 23 Jan 2017 16:02:06 -0500 Subject: [PATCH v2 3/5] xprtrdma: Disable pad optimization by default From: Chuck Lever To: anna.schumaker@netapp.com Cc: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org Date: Mon, 23 Jan 2017 15:53:02 -0500 Message-ID: <20170123205302.21699.89801.stgit@manet.1015granger.net> In-Reply-To: <20170123205159.21699.47373.stgit@manet.1015granger.net> References: <20170123205159.21699.47373.stgit@manet.1015granger.net> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: Commit d5440e27d3e5 ('xprtrdma: Enable pad optimization') made the Linux client omit XDR round-up padding in normal Read and Write chunks so that the client doesn't have to register and invalidate 3-byte memory regions that contain no real data. Unfortunately, my cheery 2014 assessment that this optimization "is supported now by both Linux and Solaris servers" was premature. We've found bugs in Solaris in this area since commit d5440e27d3e5 was merged (SYMLINK is the main culprit). So for maximum interoperability, I'm disabling this optimization again. If a CM private message is exchanged when connecting, the client recognizes that the server is Linux, and enables the optimization for that connection. Until now the Solaris server bugs did not impact common operations, and were thus largely unnoticed. Soon, less capable devices on Linux NFS/RDMA clients will make use of Read chunks more often, and these Solaris bugs will prevent interoperation in more cases. Signed-off-by: Chuck Lever --- net/sunrpc/xprtrdma/transport.c | 2 +- net/sunrpc/xprtrdma/verbs.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c index 534c178..6990581 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -67,7 +67,7 @@ static unsigned int xprt_rdma_max_inline_write = RPCRDMA_DEF_INLINE; static unsigned int xprt_rdma_inline_write_padding; static unsigned int xprt_rdma_memreg_strategy = RPCRDMA_FRMR; - int xprt_rdma_pad_optimize = 1; + int xprt_rdma_pad_optimize = 0; #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index 2a6a367..23f4da4 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -216,6 +216,7 @@ pmsg->cp_magic == rpcrdma_cmp_magic && pmsg->cp_version == RPCRDMA_CMP_VERSION) { r_xprt->rx_ia.ri_reminv_expected = true; + r_xprt->rx_ia.ri_implicit_roundup = true; rsize = rpcrdma_decode_buffer_size(pmsg->cp_send_size); wsize = rpcrdma_decode_buffer_size(pmsg->cp_recv_size); }