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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 3FD29C5517A for ; Wed, 11 Nov 2020 16:09:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5AE26206A1 for ; Wed, 11 Nov 2020 16:09:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mykernel.net header.i=cgxu519@mykernel.net header.b="Py+j5uNm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726039AbgKKQJn (ORCPT ); Wed, 11 Nov 2020 11:09:43 -0500 Received: from sender21-pp-o92.zoho.com.cn ([118.126.63.251]:25331 "EHLO sender21-pp-o92.zoho.com.cn" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726702AbgKKQJm (ORCPT ); Wed, 11 Nov 2020 11:09:42 -0500 ARC-Seal: i=1; a=rsa-sha256; t=1605110945; cv=none; d=zoho.com.cn; s=zohoarc; b=j+/QIPIaCTp/0QIDvqHFJvOerTPBvS9IglM8V8C0dfi8ouHSARyRXs49N0pgHyxvlnfI6X1JtRyTfIOzJowg9MRM00KhYhWvznXv8Zf3ASd/c1zJzL0Pi4bpWTM5t7noppsBiEwYsuVmeqsOPMwwWzkHGd6FR88U8jdq9uhZOXU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com.cn; s=zohoarc; t=1605110945; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:MIME-Version:Message-ID:Reply-To:References:Subject:To; bh=s1aqp/Y3chJfN+xDBLg0x7/Y4Bgq70OXvdHSRA/al+Y=; b=nmfx1dd+kjfblmulE/qgg6aecoCy/qPV/JTc1p02YngGSw8vo/jk3fK7JA24mAyFjFU9QnkF8dAFKZ0fgpSPQAiRKCmShtmMt7sHi4nEG8N6uqOLuLRgf9O4jXEpAAePHo7eZUNizfsvFsc92V28yLJYwXhGTqYVArVxM0IsYb4= ARC-Authentication-Results: i=1; mx.zoho.com.cn; dkim=pass header.i=mykernel.net; spf=pass smtp.mailfrom=cgxu519@mykernel.net; dmarc=pass header.from= header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1605110945; s=zohomail; d=mykernel.net; i=cgxu519@mykernel.net; h=Date:From:Reply-To:To:Cc:Message-ID:In-Reply-To:References:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding; bh=s1aqp/Y3chJfN+xDBLg0x7/Y4Bgq70OXvdHSRA/al+Y=; b=Py+j5uNmNO8Y2PaN76cN7V8tT0vldjLeaYNi5HdobDzP1WXoQKT3UNb0yOX/3ifR hRezBDWSosPGSnYTWjP7WU6doT1TVQJVbcO3stOgxzNS3TmjhdwmCpvU+JMaHE2r6SU 5tQZIAynpcACkP+C3odWNYaE9yROsqVcb/S7YlAQ= Received: from mail.baihui.com by mx.zoho.com.cn with SMTP id 1605110943133886.9861480460913; Thu, 12 Nov 2020 00:09:03 +0800 (CST) Date: Thu, 12 Nov 2020 00:09:03 +0800 From: Chengguang Xu Reply-To: cgxu519@mykernel.net To: "Amir Goldstein" Cc: "miklos" , "jack" , "linux-unionfs" , "linux-fsdevel" Message-ID: <175b8114d9a.d35f90865969.6295508804432147693@mykernel.net> In-Reply-To: References: <20201108140307.1385745-1-cgxu519@mykernel.net> <20201108140307.1385745-7-cgxu519@mykernel.net> <175b769393e.da9339695127.2777354745619336639@mykernel.net> Subject: Re: [RFC PATCH v3 06/10] ovl: mark overlayfs' inode dirty on shared mmap MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Importance: Medium User-Agent: ZohoCN Mail X-Mailer: ZohoCN Mail Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org ---- =E5=9C=A8 =E6=98=9F=E6=9C=9F=E4=B8=89, 2020-11-11 23:20:56 Amir Golds= tein =E6=92=B0=E5=86=99 ---- > On Wed, Nov 11, 2020 at 3:05 PM Chengguang Xu wro= te: > > > > ---- =E5=9C=A8 =E6=98=9F=E6=9C=9F=E6=97=A5, 2020-11-08 22:03:03 Cheng= guang Xu =E6=92=B0=E5=86=99 ---- > > > Overlayfs cannot be notified when mmapped area gets dirty, > > > so we need to proactively mark inode dirty in ->mmap operation. > > > > > > Signed-off-by: Chengguang Xu > > > --- > > > fs/overlayfs/file.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c > > > index efccb7c1f9bc..662252047fff 100644 > > > --- a/fs/overlayfs/file.c > > > +++ b/fs/overlayfs/file.c > > > @@ -486,6 +486,8 @@ static int ovl_mmap(struct file *file, struct v= m_area_struct *vma) > > > /* Drop reference count from new vm_file value */ > > > fput(realfile); > > > } else { > > > + if (vma->vm_flags & (VM_SHARED|VM_MAYSHARE)) > > > > Maybe it's better to mark dirty only having upper inode. > > >=20 > Yeh. >=20 > And since mapping_map_writable() is only called if VM_SHARED flag > is set (and not VM_MAYSHARE), we are not going to re-dirty an inode on > account of VM_MAYSHARE alone, so I wonder why we need to mark it > dirty here on account of VM_MAYSHARE? >=20 Yeah, you are right. It just means the pages in this memory region can be m= apped by other process with shared+write mode and this is actually meaningless in= our case. So let's just ignore it. :-) Thanks, Chengguang