Return-Path: linux-nfs-owner@vger.kernel.org Received: from aserp1040.oracle.com ([141.146.126.69]:45461 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753879AbaIVSr2 convert rfc822-to-8bit (ORCPT ); Mon, 22 Sep 2014 14:47:28 -0400 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Subject: Re: [PATCH] svcrdma: Advertise the correct max payload From: Chuck Lever In-Reply-To: <20140922183922.GB26763@fieldses.org> Date: Mon, 22 Sep 2014 11:47:15 -0700 Cc: Steve Wise , Linux NFS Mailing List , linux-rdma@vger.kernel.org Message-Id: <5D045AB5-71D5-4ACB-9394-FE27A9F37DA7@oracle.com> References: <20140922183653.19376.14276.stgit@build.ogc.int> <20140922183922.GB26763@fieldses.org> To: "J. Bruce Fields" Sender: linux-nfs-owner@vger.kernel.org List-ID: On Sep 22, 2014, at 11:39 AM, J. Bruce Fields wrote: > On Mon, Sep 22, 2014 at 01:36:53PM -0500, Steve Wise wrote: >> Svcrdma currently advertises 1MB, which is too large. The correct value >> is the max scatter-gather allowed in an NFSRDMA IO chunk * the host page >> size. This bug is usually benign because the Linux X64 NFSRDMA client >> correctly limits the payload size to the correct value (64*4096 = 256KB). >> But if the Linux client is PPC64 with a 64KB page size, then the client >> will indeed use a payload size that will overflow the server. >> >> Signed-off-by: Steve Wise >> --- >> >> net/sunrpc/xprtrdma/svc_rdma_transport.c | 2 +- >> net/sunrpc/xprtrdma/xprt_rdma.h | 2 ++ >> 2 files changed, 3 insertions(+), 1 deletions(-) >> >> diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c >> index 374feb4..4e61880 100644 >> --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c >> +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c >> @@ -91,7 +91,7 @@ struct svc_xprt_class svc_rdma_class = { >> .xcl_name = "rdma", >> .xcl_owner = THIS_MODULE, >> .xcl_ops = &svc_rdma_ops, >> - .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP, >> + .xcl_max_payload = RPCSVC_MAXPAYLOAD_RDMA, >> .xcl_ident = XPRT_TRANSPORT_RDMA, >> }; >> >> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h >> index c419498..467a77c 100644 >> --- a/net/sunrpc/xprtrdma/xprt_rdma.h >> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h >> @@ -392,4 +392,6 @@ extern struct kmem_cache *svc_rdma_ctxt_cachep; >> /* Workqueue created in svc_rdma.c */ >> extern struct workqueue_struct *svc_rdma_wq; >> >> +#define RPCSVC_MAXPAYLOAD_RDMA (RPCRDMA_MAX_DATA_SEGS << PAGE_SHIFT) > > Do you want to define this as the minimum of this and > RPCSVC_MAXPAYLOAD_TCP, in case RPCRDMA_MAX_DATA_SEGS gets increased some > day? Hey Bruce- I don?t see the _TCP and _RDMA settings are related. > --b. > >> + >> #endif /* _LINUX_SUNRPC_XPRT_RDMA_H */ >> > -- > 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 chuck[dot]lever[at]oracle[dot]com