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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 6A952C433EF for ; Wed, 22 Sep 2021 02:16:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C73C60F23 for ; Wed, 22 Sep 2021 02:16:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229731AbhIVCSH (ORCPT ); Tue, 21 Sep 2021 22:18:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229640AbhIVCSH (ORCPT ); Tue, 21 Sep 2021 22:18:07 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32A44C061575 for ; Tue, 21 Sep 2021 19:16:38 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id w6so752512pll.3 for ; Tue, 21 Sep 2021 19:16:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OosjfkLZh41x2OZZ5/Fq0+NUoloZ5quy7DhXoOzNYPo=; b=sc0tCxyYdZFVlGPIIr0dwpCw4M1wGDO19NAxNhEcE9rrShoOnwk3EaHGa+aje94ke8 l0y0Rw+1YzMdkaA7wYUSc3Jh/PCUzrdAni7NzXATSJy8GQG01iqBASofOsgmNUm+3mb1 Bs6s6HiOMBSDjkac4hID0AsKAWOCNExqnHBvsYxkh33xNFy0kJEm21h1lejHfVQKMIQX RESOjYS3rKj+nJP9MyN9vQj6r2vG96AKKusAHjEFho6mo0uGMIwpK1A6Wl/hGE14Bkvd E+S7ZngUtI32asDf3QYZOgY6sBh7VoMVBSQJnWdVYPvzClvgz071WetnhBmcjqfkgq8+ cz1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OosjfkLZh41x2OZZ5/Fq0+NUoloZ5quy7DhXoOzNYPo=; b=hIeiNlWFx0PGtb5U/FMHZLH4eOTkJXYNoQXtAZzRxdyxLjgZ/tY/oGfBwEQ8H7/pKe TL8eKJwCiKokMs5hOtkg9h6IByLhV26KTnnKXAtzLSS5Df2PhwKJCrcVuZ+DDV7aluir YfOESilpNb91DtJ7BuoB2r/zRrch7+8VlK20vVejdbajKRYCvTriH1GR+5fgEZAPINLf RE4mqOYOj1cTH0qixAYFLfYwZjIgsyQpQw1qtfSUOVLr1SqoW5OthqBgBduMbh7l2zQc 0H5Z0fJGfWGEGATGsGY5IKyRYQYXVoq79qitW1q0/NnILpwNQgI+pHCZNLu6fH+RYIpu ncfA== X-Gm-Message-State: AOAM5318DDlDBiNjyosc5tvD8HBQQPsS3VkMhAwnotSSVnFUm6Q1zxXP z+obN3GbCWzLOlAqyCGLbREgRJDWUEeHJRYFQ7Cw5A== X-Google-Smtp-Source: ABdhPJyclj4v0WQt0eQovMB+LlfPq/vxMuTMkF+PGvJeKggTto8OLI38FoDxRLjHCfd/IDJyVuwNh+N03sjTTLWyTj8= X-Received: by 2002:a17:90a:f18f:: with SMTP id bv15mr8398509pjb.93.1632276997599; Tue, 21 Sep 2021 19:16:37 -0700 (PDT) MIME-Version: 1.0 References: <163192864476.417973.143014658064006895.stgit@magnolia> <163192866125.417973.7293598039998376121.stgit@magnolia> <20210921004431.GO1756565@dread.disaster.area> In-Reply-To: From: Dan Williams Date: Tue, 21 Sep 2021 19:16:26 -0700 Message-ID: Subject: Re: [PATCH 3/5] vfs: add a zero-initialization mode to fallocate To: Christoph Hellwig Cc: Dave Chinner , "Darrick J. Wong" , Jane Chu , linux-xfs , linux-fsdevel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Sep 21, 2021 at 1:32 AM Christoph Hellwig wrote: > > On Tue, Sep 21, 2021 at 10:44:31AM +1000, Dave Chinner wrote: > > I think this wants to be a behavioural modifier for existing > > operations rather than an operation unto itself. i.e. similar to how > > KEEP_SIZE modifies ALLOC behaviour but doesn't fundamentally alter > > the guarantees ALLOC provides userspace. > > > > In this case, the change of behaviour over ZERO_RANGE is that we > > want physical zeros to be written instead of the filesystem > > optimising away the physical zeros by manipulating the layout > > of the file. > > Yes. > > > Then we have and API that looks like: > > > > ALLOC - allocate space efficiently > > ALLOC | INIT - allocate space by writing zeros to it > > ZERO - zero data and preallocate space efficiently > > ZERO | INIT - zero range by writing zeros to it > > > > Which seems to cater for all the cases I know of where physically > > writing zeros instead of allocating unwritten extents is the > > preferred behaviour of fallocate().... > > Agreed. I'm not sure INIT is really the right name, but I can't come > up with a better idea offhand. FUA? As in, this is a forced-unit-access zeroing all the way to media bypassing any mechanisms to emulate zero-filled payloads on future reads.