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=-2.4 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,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 D33A1C10F14 for ; Tue, 8 Oct 2019 15:13:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA02C206BB for ; Tue, 8 Oct 2019 15:13:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="mQ75tPNT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725966AbfJHPNC (ORCPT ); Tue, 8 Oct 2019 11:13:02 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:49894 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725989AbfJHPNC (ORCPT ); Tue, 8 Oct 2019 11:13:02 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x98FBmOO083559; Tue, 8 Oct 2019 15:12:55 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=68SBRTzfcPv/q/TZxoO50lTVRZcj/rpk3BTPijLLZXA=; b=mQ75tPNTTBITRe5gTTmblil96ATwPitGDAhoHo1i2K2cyAB8DVpmXrVxKfSNg+ro+YCA 9IJIqCncjNiQegI3sbFnPXBVW4dfAIiZD7hqifpGSl+9YCcpP05HDtVfUBJFCJPhNC8V aDSPT5Qdnk4YPD/eMweHLNAMhDbcAqCgQR17O4U0315qYjuhNnzvlGKX+QrXwCaY41qo SD0Nv2BiQBC7Q0hEwEN618D8fI8UfYJkWP7qoF9bsCVCbG2+VRgw1taoBUELMino6kYz 66uKiMMdDUxdzU0IJh4daSvtuqTf+XRlxxNVdrR2le/AJ/TL0viLpmnZ4MluySeihXrn DQ== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 2vek4qdxm9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 08 Oct 2019 15:12:55 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x98F97o8001699; Tue, 8 Oct 2019 15:12:55 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserp3020.oracle.com with ESMTP id 2vgefasedj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 08 Oct 2019 15:12:54 +0000 Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x98FCrgn020460; Tue, 8 Oct 2019 15:12:53 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 08 Oct 2019 15:12:52 +0000 Date: Tue, 8 Oct 2019 08:12:51 -0700 From: "Darrick J. Wong" To: Christoph Hellwig Cc: Goldwyn Rodrigues , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 06/19] iomap: use write_begin to read pages to unshare Message-ID: <20191008151251.GA13098@magnolia> References: <20190909182722.16783-1-hch@lst.de> <20190909182722.16783-7-hch@lst.de> <20190916183428.GK2229799@magnolia> <20190930110731.GA6987@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190930110731.GA6987@lst.de> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9403 signatures=668684 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=8.0.1-1908290000 definitions=main-1910080135 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9403 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910080135 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Mon, Sep 30, 2019 at 01:07:31PM +0200, Christoph Hellwig wrote: > On Mon, Sep 16, 2019 at 11:34:28AM -0700, Darrick J. Wong wrote: > > > - if ((from <= poff || from >= poff + plen) && > > > + if (!(flags & IOMAP_WRITE_F_UNSHARE) && > > > > Mmm, archeology of code that I wrote originally and have forgotten > > already... :) > > > > I think the purpose of F_UNSHARE is to mimic the behavior of the code > > that's being removed, and the old behavior is that if a user asks to > > unshare a page backed by shared extents we'll read in all the blocks > > backing the page, even if that means reading in blocks that weren't part > > of the original unshare request, right? > > No. The flag causes the code to always read the page, even if the iomap > range covers the whole block. For normal writes that means we don't to > read the block in at all, but for unshare we absolutely must do so. Ahhh, right. Missed that. I'll go RVB the v2 patch now. --D