Return-Path: Received: from mail-qg0-f41.google.com ([209.85.192.41]:35623 "EHLO mail-qg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755295AbbGTTDm (ORCPT ); Mon, 20 Jul 2015 15:03:42 -0400 Subject: [PATCH v3 08/15] xprtrdma: Account for RPC/RDMA header size when deciding to inline From: Chuck Lever To: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org Date: Mon, 20 Jul 2015 15:03:39 -0400 Message-ID: <20150720190339.10997.67723.stgit@manet.1015granger.net> In-Reply-To: <20150720185624.10997.51574.stgit@manet.1015granger.net> References: <20150720185624.10997.51574.stgit@manet.1015granger.net> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: When the size of the RPC message is near the inline threshold (1KB), the client would allow messages to be sent that were a few bytes too large. When marshaling RPC/RDMA requests, ensure the combined size of RPC/RDMA header and RPC header do not exceed the inline threshold. Endpoints typically reject RPC/RDMA messages that exceed the size of their receive buffers. The two server implementations I test with (Linux and Solaris) use receive buffers that are larger than the client’s inline threshold. Thus so far this has been benign, observed only by code inspection. Signed-off-by: Chuck Lever Reviewed-by: Devesh Sharma Tested-by: Devesh Sharma --- net/sunrpc/xprtrdma/rpc_rdma.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index 8e9c564..950b654 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -71,6 +71,31 @@ static const char transfertypes[][12] = { }; #endif +/* The client can send a request inline as long as the RPCRDMA header + * plus the RPC call fit under the transport's inline limit. If the + * combined call message size exceeds that limit, the client must use + * the read chunk list for this operation. + */ +static bool rpcrdma_args_inline(struct rpc_rqst *rqst) +{ + unsigned int callsize = RPCRDMA_HDRLEN_MIN + rqst->rq_snd_buf.len; + + return callsize <= RPCRDMA_INLINE_WRITE_THRESHOLD(rqst); +} + +/* The client can't know how large the actual reply will be. Thus it + * plans for the largest possible reply for that particular ULP + * operation. If the maximum combined reply message size exceeds that + * limit, the client must provide a write list or a reply chunk for + * this request. + */ +static bool rpcrdma_results_inline(struct rpc_rqst *rqst) +{ + unsigned int repsize = RPCRDMA_HDRLEN_MIN + rqst->rq_rcv_buf.buflen; + + return repsize <= RPCRDMA_INLINE_READ_THRESHOLD(rqst); +} + /* * Chunk assembly from upper layer xdr_buf. * @@ -409,7 +434,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst) * a READ, then use write chunks to separate the file data * into pages; otherwise use reply chunks. */ - if (rqst->rq_rcv_buf.buflen <= RPCRDMA_INLINE_READ_THRESHOLD(rqst)) + if (rpcrdma_results_inline(rqst)) wtype = rpcrdma_noch; else if (rqst->rq_rcv_buf.page_len == 0) wtype = rpcrdma_replych; @@ -432,7 +457,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst) * implies the op is a write. * TBD check NFSv4 setacl */ - if (rqst->rq_snd_buf.len <= RPCRDMA_INLINE_WRITE_THRESHOLD(rqst)) + if (rpcrdma_args_inline(rqst)) rtype = rpcrdma_noch; else if (rqst->rq_snd_buf.page_len == 0) rtype = rpcrdma_areadch;