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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 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 992B8C43215 for ; Wed, 27 Nov 2019 20:21:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 700CC20863 for ; Wed, 27 Nov 2019 20:21:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="NCD166Ac" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727010AbfK0UVr (ORCPT ); Wed, 27 Nov 2019 15:21:47 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:41582 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726703AbfK0UVr (ORCPT ); Wed, 27 Nov 2019 15:21:47 -0500 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xARKJvRU126170; Wed, 27 Nov 2019 20:21:43 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2019-08-05; bh=95mfLhm4vghNr8cf39wWPNrlxfRQ9+/3VOjVBZT7JzY=; b=NCD166AcV9/rhzIIX/QgAs4CIE3Fs1OMwo7tJh/SjzDS1WAtlhtJE9m65MDMb34cKlhT RVkU4uMN/eNSbFiPZo/4uZnkX9W+h7ncRgcCmK8CkzMhHY9KSAAzPZgaHnyrV5mn7Eiy Lo0EPDpooUidRqfZbnTRQBaSIiONTJtLJmcHdS7aIp5DsXjDJRqekgnbghQLnxyUX25V 7qty/MGC3b2TV5bRte5bXZP/rWs25C7EyNz20gUl5Ly1Jh2kv8SpgeyNzrWEP1MnzQ+x elDpRrnXQ2RBBavtDpU6Z/6D0BCDRgqHHUwBxZWAj8ul99HVXN3hBv+RSzKgj8RjVe9V nQ== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2130.oracle.com with ESMTP id 2wev6uftg2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 Nov 2019 20:21:42 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xARKJ4Fa092823; Wed, 27 Nov 2019 20:21:42 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 2whx5r556n-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 Nov 2019 20:21:42 +0000 Received: from abhmp0019.oracle.com (abhmp0019.oracle.com [141.146.116.25]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id xARKLcMZ028437; Wed, 27 Nov 2019 20:21:40 GMT Received: from localhost (/10.145.178.64) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 27 Nov 2019 12:21:38 -0800 Date: Wed, 27 Nov 2019 12:21:36 -0800 From: "Darrick J. Wong" To: Trond Myklebust Cc: "linux-fsdevel@vger.kernel.org" , "linux-nfs@vger.kernel.org" Subject: Re: Question about clone_range() metadata stability Message-ID: <20191127202136.GV6211@magnolia> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9454 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911270163 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9454 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911270163 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Nov 27, 2019 at 06:38:46PM +0000, Trond Myklebust wrote: > Hi all > > A quick question about clone_range() and guarantees around metadata > stability. > > Are users required to call fsync/fsync_range() after calling > clone_range() in order to guarantee that the cloned range metadata is > persisted? Yes. > I'm assuming that it is required in order to guarantee that > data is persisted. Data and metadata. XFS and ocfs2's reflink implementations will flush the page cache before starting the remap, but they both require fsync to force the log/journal to disk. (AFAICT the same reasoning applies to btrfs, but don't trust my word for it.) > I'm asking because knfsd currently just does a call to > vfs_clone_file_range() when parsing a NFSv4.2 CLONE operation. It does > not call fsync()/fsync_range() on the destination file, and since the > NFSv4.2 protocol does not require you to perform any other operation in > order to persist data/metadata, I'm worried that we may be corrupting > the cloned file if the NFS server crashes at the wrong moment after the > client has been told the clone completed. That analysis seems correct. --D > Cheers > Trond > -- > Trond Myklebust > Linux NFS client maintainer, Hammerspace > trond.myklebust@hammerspace.com > >