From 9191ca3b381b15b9a88785a8ae2fa4db8e553b0c Mon Sep 17 00:00:00 2001 From: Tom Talpey Date: Thu, 9 Oct 2008 15:01:11 -0400 Subject: RPC/RDMA: adhere to protocol for unpadded client trailing write chunks. The RPC/RDMA protocol allows clients and servers to avoid RDMA operations for data which is purely the result of XDR padding. On the client, automatically insert the necessary padding for such server replies, and optionally don't marshal such chunks. Signed-off-by: Tom Talpey Signed-off-by: Trond Myklebust --- net/sunrpc/xprtrdma/rpc_rdma.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'net/sunrpc/xprtrdma/rpc_rdma.c') diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index 721dae795d6..d245c0bf787 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -118,6 +118,10 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos, } if (xdrbuf->tail[0].iov_len) { + /* the rpcrdma protocol allows us to omit any trailing + * xdr pad bytes, saving the server an RDMA operation. */ + if (xdrbuf->tail[0].iov_len < 4 && xprt_rdma_pad_optimize) + return n; if (n == nsegs) return 0; seg[n].mr_page = NULL; @@ -594,7 +598,7 @@ rpcrdma_count_chunks(struct rpcrdma_rep *rep, unsigned int max, int wrchunk, __b * Scatter inline received data back into provided iov's. */ static void -rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len) +rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad) { int i, npages, curlen, olen; char *destp; @@ -660,6 +664,13 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len) } else rqst->rq_rcv_buf.tail[0].iov_len = 0; + if (pad) { + /* implicit padding on terminal chunk */ + unsigned char *p = rqst->rq_rcv_buf.tail[0].iov_base; + while (pad--) + p[rqst->rq_rcv_buf.tail[0].iov_len++] = 0; + } + if (copy_len) dprintk("RPC: %s: %d bytes in" " %d extra segments (%d lost)\n", @@ -794,14 +805,20 @@ repost: ((unsigned char *)iptr - (unsigned char *)headerp); status = rep->rr_len + rdmalen; r_xprt->rx_stats.total_rdma_reply += rdmalen; + /* special case - last chunk may omit padding */ + if (rdmalen &= 3) { + rdmalen = 4 - rdmalen; + status += rdmalen; + } } else { /* else ordinary inline */ + rdmalen = 0; iptr = (__be32 *)((unsigned char *)headerp + 28); rep->rr_len -= 28; /*sizeof *headerp;*/ status = rep->rr_len; } /* Fix up the rpc results for upper layer */ - rpcrdma_inline_fixup(rqst, (char *)iptr, rep->rr_len); + rpcrdma_inline_fixup(rqst, (char *)iptr, rep->rr_len, rdmalen); break; case __constant_htonl(RDMA_NOMSG): -- cgit v1.2.3-70-g09d2