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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 248B5C3F68F for ; Wed, 22 Jan 2020 05:52:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C430E24656 for ; Wed, 22 Jan 2020 05:52:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=aol.com header.i=@aol.com header.b="qo3RdUCx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C430E24656 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=aol.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1F52D6B0003; Wed, 22 Jan 2020 00:52:39 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1A5146B0005; Wed, 22 Jan 2020 00:52:39 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0BC116B0007; Wed, 22 Jan 2020 00:52:39 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0024.hostedemail.com [216.40.44.24]) by kanga.kvack.org (Postfix) with ESMTP id E95726B0003 for ; Wed, 22 Jan 2020 00:52:38 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id B0891180AD804 for ; Wed, 22 Jan 2020 05:52:38 +0000 (UTC) X-FDA: 76404200796.24.sun96_342438b089251 X-HE-Tag: sun96_342438b089251 X-Filterd-Recvd-Size: 4295 Received: from sonic308-8.consmr.mail.gq1.yahoo.com (sonic308-8.consmr.mail.gq1.yahoo.com [98.137.68.32]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Wed, 22 Jan 2020 05:52:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=aol.com; s=a2048; t=1579672357; bh=m1TngP7v9QL/OgWrRHhkzeVM3vncCixxyVZeB4KwRZ4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From:Subject; b=qo3RdUCxF4AfHSJ5PSS/h/k33yZKiOCo7go1I0BIP8Z/He3Ag+pufxCt8LoQY4Kpok8Zl5QklM4G/vVvRpAm3Yj/N5tKZ8KU8cZchg0v/Pt4hE4R6hMojfthZYegxoWcAuw/JGpMiSjmUqyd2oO4NNmdBuK6dcP+WqdqILPp9tWnNUmCugl1jplDHSCgxFRssTYax+qipLBGxRd0ULe5xUdx9TRYHyuktfllE2jRvwOPQfCEkU6ijUc1qvs0fBvrCPX6MqJgsoiCsAve644bzjYicM66e3QSErt+twJyStESQ8BTF1kL5Skp6kOPXeXRzATac4jyGIMkvLI/r7nGRQ== X-YMail-OSG: kwOrWiIVM1kPRerBHD4KV9c_.znfhEmpefevnFHuDik7P5OFlUXAXUJLBYqoAkN YfvtpUo7brnrE3UmtMyrNBvnOtEYvp7.kxu_UISFzTFbAlAUczh7T4gmXGX31.qszPIlMLdgIgGk zqNaqkgohImF8MZjxw_UXEV0S8dyVSr2j1Ez.n.1cND4Zn1i7zmv1moc8c0afpJw.snY1i7CUzvf hy_17BlL8lQPpc0u5WLOksHvAz0gffAYJcp0SSsys.ubkzvmPxRECQ5GulZ8GiSY6fVOwGUIJHg1 fbRbIF0VVLaLCTNjqS4AuBISq2enpUAsQ4uKjGyGF3zLQfZ.cUvOa27oYQvNncA86hHiEQVacCrg 4xm_CHZWajHb8Tp1gUH5ii_Fl3eP6nCrqurqT2fvZ2OZCkDe.a1paouiFUG09vRL7dKEwQ51qc7W zu6l1AwFEI8XKv.F2ot_wHSRvKJjMC.Musu5XPVyXTq2OyPNKww7scvyx9RH9dujLqZbRwI3BRG. SMVDSkbU7mDOcRWuUPS2FW.QNc4x_33t.TYLppd2ktpbYeLetc7b9ycfT69.wyBI7X0F27tItgzW TNlyAdzT6x9lgrEHJphE83ZPJYKHQVwRkl_x4h5HkufpyYXvIhPiiP5uvY6QpFZMxlhj4ngto.Jp WOrnthc5DDqiDcGgk0M.v8UNZAJHQqgqQdVTGdMsk4go06p1h7bMkIPXdwEpSSKboBJd3eCekF5G 3fGj2EovVNEnTR0oCLB25bylgXMUkevOpFh8lM3mJ2iOnMZPbLd0MebUdfxelUtFrTqZFgUODTez x.Mx8bDDQMrCPtDZu7.TDnFjlKzn8dwzUK2bSG3i4EUR5R2soVlYB7UN0iPi3BSpXGvlJwfXs6Ws PqdUhhGf83ijlZOjn0.5leFqStedC1mSqyXmOcAaf7YPBtP6Ckl6QI91Xf9eHti93m6P5rJKOvDB adB8UBzcgEG_nLAzeaUvwuj7rVZVjs3TbCNVvVYUCCLsnvgIbMtYVO_ih68Dt3YH0qs9_XiWmrzZ S.xWNbzT0ICWcZ.MVbvFJaxWXku.IaURXYbdgqZtWZLxRF5vR_4FCuEwBar1SSWdgOM0fuqkYglO aSUGzDMlP2._lnFXoI8YskG6YNNNOAiVl7BmAOVSTQHc9ouR7AFdFbpZYth75lVb9cPM0twsTTBY bRBm8Qt6s15c3sgBNh6jAZqVB0rwVh2lAZNv0qSHlCOdNHwIQVnteXqefuzCCkKCZ8T3N50C7TY_ 5YXaJ_dNT8gEVk5F6Ev5vJ1GfGq_PD7iy2HdBDGP4FlmVxT8uMPgieXqNSK.M5eRGKx8b53beTIM qOi5s7xOAi2PJ3Rb2NZBUKZ7n1uxqTbRBG9Ywc2SY9xckf1wHInVtqhJfjDXwN1rNorILg_6wIaB SufA6mQ-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic308.consmr.mail.gq1.yahoo.com with HTTP; Wed, 22 Jan 2020 05:52:37 +0000 Received: by smtp424.mail.gq1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID 4a02ce608c48d5a20a659077844e8e1d; Wed, 22 Jan 2020 05:52:32 +0000 (UTC) Date: Wed, 22 Jan 2020 13:52:26 +0800 From: Gao Xiang To: Jerome Glisse Cc: lsf-pc@lists.linux-foundation.org, Andrea Arcangeli , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org Subject: Re: [LSF/MM/BPF TOPIC] Generic page write protection Message-ID: <20200122055219.GC6542@hsiangkao-HP-ZHAN-66-Pro-G1> References: <20200122023222.75347-1-jglisse@redhat.com> <20200122042832.GA6542@hsiangkao-HP-ZHAN-66-Pro-G1> <20200122052118.GE76712@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200122052118.GE76712@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Mailer: WebService/1.1.14873 hermes Apache-HttpAsyncClient/4.1.4 (Java/1.8.0_181) X-Bogosity: Ham, tests=bogofilter, spamicity=0.287485, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jan 21, 2020 at 09:21:18PM -0800, Jerome Glisse wrote: > > The block device code only need the mapping on io error and they are > different strategy depending on individual fs. fs using buffer_head > can easily be updated. For other they are different solution and they > can be updated one at a time with tailor solution. If I did't misunderstand, how about post-processing fs code without some buffer_head but page->private used as another way rather than a pointer? (Yes, some alternative ways exist such as hacking struct bio_vec...) I wonder the final plan on this from the community, learn new rule and adapt my code anyway.. But in my opinion, such reserve way (page->mapping likewise) is helpful in many respects, I'm not sure we could totally get around all cases without it elegantly... Thank you... Thanks, Gao Xiang