From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D7B6C6379D for ; Mon, 23 Nov 2020 17:49:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 52D3B2076E for ; Mon, 23 Nov 2020 17:49:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="aujPKkpr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388467AbgKWRtS (ORCPT ); Mon, 23 Nov 2020 12:49:18 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:34120 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726817AbgKWRtS (ORCPT ); Mon, 23 Nov 2020 12:49:18 -0500 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0ANHjUhv029957; Mon, 23 Nov 2020 17:49:13 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=content-type : mime-version : subject : from : in-reply-to : date : cc : content-transfer-encoding : message-id : references : to; s=corp-2020-01-29; bh=kUTQcWCj+U6Ib5Pkea9ZZiSSajLZyIAqMUGlVO+NZ1c=; b=aujPKkpr767yS0vUs+WioJNQ1aPEuYbhQB5c673euv8kZSHbpXpK6OngCoXVi4rt91FT FDoD4Rv1POrRTgRUpw++kbedgSVfgSlYwCyIILNoSYIBMiwLmOb58UxxAQ1MSuyvIQG/ BSQfftdg0Mm4epYW6paaiPiewu4WI+yvxdqCyg5FIy2pEbk5H/4OFmltJtooZLjtsa/a 57pWSsYHq/dQcgRet8vq0jiud/x34LCqsmOp4biUuvvTo1REYTFGdoQgWeGqTyma5EKB nt9+utRgS4nZnx5wnyeCG6c1yjBj1SgtjqIonrVqW99kW5uG5R+Z4i+PWSgBp+nDehuk 0Q== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 34xtaqj1s1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 23 Nov 2020 17:49:12 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0ANHdppr054774; Mon, 23 Nov 2020 17:49:12 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3020.oracle.com with ESMTP id 34ycnr8bh5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 23 Nov 2020 17:49:12 +0000 Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 0ANHnBOs024222; Mon, 23 Nov 2020 17:49:11 GMT Received: from anon-dhcp-152.1015granger.net (/68.61.232.219) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 23 Nov 2020 09:49:11 -0800 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.4\)) Subject: Re: [PATCH 1/1] NFSv4.2: fix LISTXATTR buffer receive size From: Chuck Lever In-Reply-To: <20201123173802.GA26158@dev-dsk-fllinden-2c-c1893d73.us-west-2.amazon.com> Date: Mon, 23 Nov 2020 12:49:09 -0500 Cc: Olga Kornievskaia , Trond Myklebust , Anna Schumaker , Linux NFS Mailing List Content-Transfer-Encoding: quoted-printable Message-Id: References: <20201113190851.7817-1-olga.kornievskaia@gmail.com> <99874775-A18C-4832-A2F0-F2152BE5CE32@oracle.com> <07AF9A5C-BC42-4F66-A153-19A410D312E1@oracle.com> <7E0CD3F3-84F2-4D08-8D5A-37AA0FA4852D@oracle.com> <20201119232647.GA11369@dev-dsk-fllinden-2c-c1893d73.us-west-2.amazon.com> <20201123173802.GA26158@dev-dsk-fllinden-2c-c1893d73.us-west-2.amazon.com> To: Frank van der Linden X-Mailer: Apple Mail (2.3608.120.23.2.4) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9814 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 suspectscore=0 mlxlogscore=999 phishscore=0 spamscore=0 malwarescore=0 adultscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011230118 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9814 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 spamscore=0 phishscore=0 mlxlogscore=999 clxscore=1015 suspectscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 impostorscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011230118 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org > On Nov 23, 2020, at 12:38 PM, Frank van der Linden = wrote: >=20 > On Mon, Nov 23, 2020 at 11:42:46AM -0500, Olga Kornievskaia wrote: >> Hi Frank, Chuck, >>=20 >> I would like your option on how LISTXATTR is supposed to work over >> RDMA. Here's my current understanding of why the listxattr is not >> working over the RDMA. >>=20 >> This happens when the listxattr is called with a very small buffer >> size which RDMA wants to send an inline request. I really dont >> understand why, Chuck, you are not seeing any problems with hardware >> as far as I can tell it would have the same problem because the = inline >> threshold size would still make this size inline. >> rcprdma_inline_fixup() is trying to write to pages that don't exist. >>=20 >> When LISTXATTR sets this flag XDRBUF_SPARSE_PAGES there is code that >> will allocate pages in xs_alloc_sparse_pages() but this is ONLY for >> TCP. RDMA doesn't have anything like that. >>=20 >> Question: Should there be code added to RDMA that will do something >> similar when it sees that flag set? Or, should LISTXATTR be = re-written >> to be like READDIR which allocates pages before calling the code. >=20 > Hm.. so if the flag never worked for RDMA, was NFS_V3_ACL ever tested > over RDMA? That's the only other user. >=20 > If the flag simply doesn't work, I agree that it should either be = fixed > or just removed. Shirley fixed a crasher here years ago by making SPARSE_PAGES work for RPC/RDMA. She confirmed the fix was effective. > It wouldn't be the end of the world to change LISTXATTRS (and = GETXATTR) > to use preallocated pages. But, I didn't do that because I didn't want = to > waste the max size (64k) every time, even though you usually just get > a few hundred bytes at most. So it seems like fixing = XDRBUF_SPARSE_PAGES > is cleaner. These are infrequent operations. We've added extra conditional branches in the hot path of the transports to handle this rare, non-performance sensitive case. I also wonder how well SPARSE_PAGES will work with xdr->bvecs, since the bio_vec array is constructed before the transport can allocate those pages. To me, the whole SPARSE_PAGES concept is prototype-quality code that needs to be replaced with a robust permanent solution. -- Chuck Lever