Return-Path: linux-nfs-owner@vger.kernel.org Received: from aserp1040.oracle.com ([141.146.126.69]:51045 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751996Ab3KOVjy convert rfc822-to-8bit (ORCPT ); Fri, 15 Nov 2013 16:39:54 -0500 From: Chuck Lever Content-Type: text/plain; charset=us-ascii Subject: Re: NFS over RDMA stops working for data larger than 812 Bytes Date: Fri, 15 Nov 2013 16:39:46 -0500 Message-Id: <24663A6D-A54A-441B-880E-BB7FD6BBB3F2@oracle.com> Cc: Klemens Senn , Linux NFS Mailing List To: Trond Myklebust Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) Sender: linux-nfs-owner@vger.kernel.org List-ID: Hi Trond- Klemens Senn says: > Hi, > > I started setting up NFS over RDMA on a OpenSUSE 12.3 machine using the > 3.7.10-1.16-default kernel. > Mounting the NFS share works and getting a file with 812 Bytes succeeds. > Reading 813 Bytes raises a Input/output error. > > The export on the server side is done with > /data > 172.16.100.0/24(rw,wdelay,crossmnt,insecure,no_root_squash,no_subtree_check,fsid=0,mountpoint) > > Following command is used for mounting the NFSv4 share: > mount -t nfs -o port=20049,rdma,vers=4.0,timeo=900 172.16.100.2:/ /mnt/ > > Testing the client side with older kernels stated that the mount is > working properly with the 3.4.67 kernel. I continued testing with the > 3.10.17 kernel and enabled the debug level and noticed the message > "server cheating in read reply: count 813 > recvd 0" > > Here is the syslog output: > NFS: read(//813_bytes, 262144@0) > NFS: nfs_readpage (ffffea001db1e898 4096@0) > NFS: 0 initiated read call (req 0:33/70, 813 bytes @ offset 0) > RPC: new task initialized, procpid 9881 > RPC: allocated task ffff88105dacabf8 > RPC: 1631 __rpc_execute flags=0x1 > <-- nfs4_setup_sequence status=0 > RPC: 1631 call_start nfs4 proc READ (async) > RPC: 1631 call_reserve (status 0) > RPC: 1631 reserved req ffff88085e641c00 xid 3f6a89a6 > RPC: 1631 call_reserveresult (status 0) > RPC: 1631 call_refresh (status 0) > RPC: 1631 refreshing UNIX cred ffff88087c2108c0 > RPC: 1631 call_refreshresult (status 0) > RPC: 1631 call_allocate (status 0) > RPC: xprt_rdma_allocate: size 684, request 0xffff88084a342000 > RPC: 1631 call_bind (status 0) > RPC: 1631 call_connect xprt ffff88085f297000 is connected > RPC: 1631 call_transmit (status 0) > RPC: 1631 xprt_prepare_transmit > RPC: 1631 xprt_cwnd_limited cong = 0 cwnd = 4096 > RPC: 1631 rpc_xdr_encode (status 0) > RPC: 1631 marshaling UNIX cred ffff88087c2108c0 > RPC: 1631 using AUTH_UNIX cred ffff88087c2108c0 to wrap rpc data > RPC: 1631 xprt_transmit(144) > RPC: rpcrdma_inline_pullup: pad 0 destp 0xffff88084a3437f0 len 144 > hdrlen 144 > RPC: rpcrdma_register_frmr_external: Using frmr ffff88084b612d10 > to map 1 segments > RPC: rpcrdma_create_chunks: write chunk elem > 813@0x87bf95000:0x8a905 (more) > RPC: rpcrdma_register_frmr_external: Using frmr ffff88084b612d38 > to map 1 segments > RPC: rpcrdma_create_chunks: write chunk elem > 152@0x84a343974:0x8aa01 (last) > RPC: rpcrdma_marshal_req: write chunk: hdrlen 68 rpclen 144 padlen > 0 headerp 0xffff88084a343100 base 0xffff88084a343760 lkey 0x8000 > RPC: rpcrdma_event_process: event rep ffff88084b612d10 status 0 > opcode 8 length 4294936584 > RPC: rpcrdma_event_process: event rep ffff88084b612d38 status 0 > opcode 8 length 4294936584 > RPC: 1631 xmit complete > RPC: 1631 sleep_on(queue "xprt_pending" time 4296115067) > RPC: 1631 added to queue ffff88085f297258 "xprt_pending" > RPC: 1631 setting alarm for 90000 ms > RPC: wake_up_first(ffff88085f297190 "xprt_sending") > RPC: rpcrdma_event_process: event rep ffff88085e8bf000 status 0 > opcode 80 length 128 > RPC: rpcrdma_reply_handler: reply 0xffff88085e8bf000 completes > request 0xffff88084a342000 > RPC request 0xffff88085e641c00 xid 0xa6896a3f > RPC: rpcrdma_count_chunks: chunk 813@0x87bf95000:0x8a905 > RPC: rpcrdma_count_chunks: chunk 3@0x84a343974:0x8aa01 > RPC: rpcrdma_inline_fixup: srcp 0xffff88085e8bf0a4 len 60 hdrlen 60 > RPC: rpcrdma_reply_handler: xprt_complete_rqst(0xffff88085f297000, > 0xffff88085e641c00, 876) > RPC: 1631 xid 3f6a89a6 complete (876 bytes received) > RPC: 1631 __rpc_wake_up_task (now 4296115067) > RPC: 1631 disabling timer > RPC: 1631 removed from queue ffff88085f297258 "xprt_pending" > RPC: __rpc_wake_up_task done > RPC: 1631 __rpc_execute flags=0x801 > RPC: 1631 call_status (status 876) > RPC: 1631 call_decode (status 876) > RPC: 1631 validating UNIX cred ffff88087c2108c0 > RPC: 1631 using AUTH_UNIX cred ffff88087c2108c0 to unwrap rpc data > NFS: server cheating in read reply: count 813 > recvd 0 > RPC: 1631 call_decode result 0 > NFS: nfs_readpage_result: 1631, (status 0) > --> nfs4_read_done > > Adding other debug prints to the kernel module told me that > buf->page_len is set to 0 in xdr_align_pages (in file net/sunrpc/xdr.c). > Comparing this piece of code with older kernel versions showed that the > comparison with buf->page_len was introduces in kernel 3.7. > By disabling this check the file transfer seems to work. > > Here is the patch for kernel 3.10.17: > > --- net/sunrpc/xdr.c 2013-10-18 19:44:19.000000000 +0200 > +++ net/sunrpc/xdr_new.c 2013-11-08 14:06:00.241217773 +0100 > @@ -747,7 +747,7 @@ > nwords = xdr->nwords; > len = nwords << 2; > } > - if (buf->page_len <= len) > + if (buf->page_len && buf->page_len <= len) > len = buf->page_len; > else if (nwords < xdr->nwords) { > /* Truncate page data and move it into the tail */ > > > Can you please tell me which entity sets (or does not set) the total > length (buf->page_len) after receiving the data from the RDMA_SEND > operation from the server? > > Please advise > > Klemens Comparing xdr_align_pages() before commit a11a2bf4 and afterwords, it appears that it no longer handles cases where buf->page_len == 0 the same way it used to. xdr_align_pages() would never return zero unless xdr->nwords was zero. -- Chuck Lever chuck[dot]lever[at]oracle[dot]com