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=-0.8 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 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 DB0E0C76196 for ; Mon, 22 Jul 2019 04:39:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B670D21BF1 for ; Mon, 22 Jul 2019 04:39:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="t/VUEFE9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727659AbfGVEjk (ORCPT ); Mon, 22 Jul 2019 00:39:40 -0400 Received: from mail-yw1-f67.google.com ([209.85.161.67]:34710 "EHLO mail-yw1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726547AbfGVEjk (ORCPT ); Mon, 22 Jul 2019 00:39:40 -0400 Received: by mail-yw1-f67.google.com with SMTP id q128so15435671ywc.1; Sun, 21 Jul 2019 21:39:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OMqsPQOjQqPIEBmD3EIh4Qtw05vaz+UOfW4nYOJHTL4=; b=t/VUEFE9R2TvEBxbMNvsYCoL2WZYdDc0V4kRWpaHd/rCAxdQIa436PxuYFihm/ifDL H5FDSOR4DAcsJfHRaXAU2y1fOgiHivBPZDcNU+NKvX/KOFe0+TIojO7yzrLOaCpfSgyH 8w8H1swbhb7jAhafPPfws0q8ehyTp/OIOqdO5fSa9w6TNw/A3QFZcpZ7zIQOcFFirqf3 rRY81Z8vai/trJWZwFmj3nqB2pLuwZujCtzdqgYaUFY39SgnBtvz0FEizNU7qvcPe1iZ 9Cd4RFJF9WGz6EuAuJQeCzPQRQ2HfRrXe7rRYmw/vjWiISrRX9vt1y7X3WVeck0H9Ayf 1UGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OMqsPQOjQqPIEBmD3EIh4Qtw05vaz+UOfW4nYOJHTL4=; b=NEPa6hHNRQdxAqyHmFex++84zd5bg/a2MmgFt+4fiq/a0EwbUe1N3qU/NcLlQxjasj YpYwlupQWTnM2xr7864s7iNZQreVL1P9NE/oJmBLhAJJO2NARKu6J946FfBkmTDsV5FH MrEQfOxUZuYyAJ/tSVp//elG75nCGJkxlSmrryA9Y6bUJOwZd1Z103Ed+41IqY4Qii5+ 7rM90Y+43Q36q2e08Qj1/FzjLl5Du+i2lcdzPf0irDJT6PF4lvB28pTeWVWTNFTgl3lV EQ7nIIVthKORXQSr2g9iZA5DSJdTvPYM4WEK2h0nXgnQrEMaWziGdrqGqDQ20RhGYKW4 A+cw== X-Gm-Message-State: APjAAAUv3g1CWTIpOvfZ8V4Cs1vZm7jCWr5sUKmkxmDwH/Cfflt9nVsz XTKA297oFdvdnawE5D6NfNebluBDuB0nPaxuaZQ= X-Google-Smtp-Source: APXvYqw2nuO6UwixpRbfaNpk9MK1Ao8/qBkIZzg+dLv0cDdjoBg3WbnEO02wQKi8/VMw4pkqKPvLqF4+21jZlLPQ/AY= X-Received: by 2002:a81:50d5:: with SMTP id e204mr39589702ywb.379.1563770379165; Sun, 21 Jul 2019 21:39:39 -0700 (PDT) MIME-Version: 1.0 References: <20190722025043.166344-1-gaoxiang25@huawei.com> <20190722025043.166344-13-gaoxiang25@huawei.com> In-Reply-To: <20190722025043.166344-13-gaoxiang25@huawei.com> From: Amir Goldstein Date: Mon, 22 Jul 2019 07:39:27 +0300 Message-ID: Subject: Re: [PATCH v3 12/24] erofs: introduce tagged pointer To: Gao Xiang Cc: Alexander Viro , Greg Kroah-Hartman , Andrew Morton , Stephen Rothwell , "Theodore Ts'o" , Linus Torvalds , linux-fsdevel , devel@driverdev.osuosl.org, LKML , linux-erofs@lists.ozlabs.org, Chao Yu , Miao Xie , Li Guifu , Fang Wei Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 22, 2019 at 5:54 AM Gao Xiang wrote: > > Currently kernel has scattered tagged pointer usages > hacked by hand in plain code, without a unique and > portable functionset to highlight the tagged pointer > itself and wrap these hacked code in order to clean up > all over meaningless magic masks. > > This patch introduces simple generic methods to fold > tags into a pointer integer. Currently it supports > the last n bits of the pointer for tags, which can be > selected by users. > > In addition, it will also be used for the upcoming EROFS > filesystem, which heavily uses tagged pointer pproach > to reduce extra memory allocation. > > Link: https://en.wikipedia.org/wiki/Tagged_pointer Well, it won't do much good for other kernel users in fs/erofs/ ;-) I think now would be a right time to promote this facility to include/linux as you initially proposed. I don't recall you got any objections. No ACKs either, but I think that was the good kind of silence (?) You might want to post the __fdget conversion patch [1] as a bonus patch on top of your series. Thanks, Amir. [1] https://lore.kernel.org/linux-fsdevel/1530543233-65279-2-git-send-email-gaoxiang25@huawei.com/