Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-ig0-f173.google.com ([209.85.213.173]:55278 "EHLO mail-ig0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750722AbaGOOLi (ORCPT ); Tue, 15 Jul 2014 10:11:38 -0400 Received: by mail-ig0-f173.google.com with SMTP id h18so2950634igc.6 for ; Tue, 15 Jul 2014 07:11:37 -0700 (PDT) From: Chuck Lever Subject: [PATCH] svcrdma: Add zero padding if the client doesn't send it To: bfields@fieldses.org Cc: linux-nfs@vger.kernel.org Date: Tue, 15 Jul 2014 10:11:34 -0400 Message-ID: <20140715140417.23046.27242.stgit@klimt.1015granger.net> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: See RFC 5666 section 3.7: clients don't have to send zero XDR padding. BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=246 Signed-off-by: Chuck Lever --- Hi Bruce- This is an alternative solution to changing the sanity check in the XDR WRITE decoder. It adjusts the incoming xdr_buf to include a zero pad just after the transport has received each RPC request. Thoughts? net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 30 ++++++++++++++++++++++++++++++ 1 files changed, 30 insertions(+), 0 deletions(-) diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index 8f92a61..9a3465d 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include #include @@ -435,6 +436,34 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt, return ret; } +/* + * To avoid a separate RDMA READ just for a handful of zero bytes, + * RFC 5666 section 3.7 allows the client to omit the XDR zero pad + * in chunk lists. + */ +static void +rdma_fix_xdr_pad(struct xdr_buf *buf) +{ + unsigned int page_len = buf->page_len; + unsigned int size = (XDR_QUADLEN(page_len) << 2) - page_len; + unsigned int offset, pg_no; + char *p; + + if (size == 0) + return; + + offset = page_len & ~PAGE_MASK; + pg_no = page_len >> PAGE_SHIFT; + + p = kmap_atomic(buf->pages[pg_no]); + memset(p + offset, 0, size); + kunmap_atomic(p); + + buf->page_len += size; + buf->buflen += size; + buf->len += size; +} + static int rdma_read_complete(struct svc_rqst *rqstp, struct svc_rdma_op_ctxt *head) { @@ -449,6 +478,7 @@ static int rdma_read_complete(struct svc_rqst *rqstp, rqstp->rq_pages[page_no] = head->pages[page_no]; } /* Point rq_arg.pages past header */ + rdma_fix_xdr_pad(&head->arg); rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count]; rqstp->rq_arg.page_len = head->arg.page_len; rqstp->rq_arg.page_base = head->arg.page_base;