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=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 A03C3C432BE for ; Sat, 24 Jul 2021 08:05:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85590608FE for ; Sat, 24 Jul 2021 08:05:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234654AbhGXHY6 (ORCPT ); Sat, 24 Jul 2021 03:24:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234216AbhGXHY5 (ORCPT ); Sat, 24 Jul 2021 03:24:57 -0400 Received: from mail-io1-xd36.google.com (mail-io1-xd36.google.com [IPv6:2607:f8b0:4864:20::d36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B1683C061575; Sat, 24 Jul 2021 01:05:29 -0700 (PDT) Received: by mail-io1-xd36.google.com with SMTP id r6so5285145ioj.8; Sat, 24 Jul 2021 01:05:29 -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=9SULVsagS4dB16WkbeqR+XAZ1fs3eU5Cq64+TOTbFWY=; b=hCsvguMMppyHLeUqzy7b/2A0qHFFJVBIADGsDmSCI8yECsuZ2jO3mPcqJZx0aeRnJC R63o6SfNDxboorkvGgwv0Bl3oESZyIursuPhDgTYp4JYtm41hOFDdvttr/HLEaEiVS8r LVbajxGI2vBRj+hRzdTOUYlqSqTkO5iPnGBQTARhcYacMY7XZQCIAUMTTmKyB8sKevUY fbFAQu/TOena2uYMzK0Ud3wTzLZkemjmOnV8fLZqEcgU2KOu4DHRHHs95tZXUBw6a+bT x0B1bz59erq+fUFGyq2k3hlXy3BvI5pmjoNWyj6IDAU2eNE01O+cgq+VYx/8olyZyZR0 QhWg== 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=9SULVsagS4dB16WkbeqR+XAZ1fs3eU5Cq64+TOTbFWY=; b=XS5OoJz8c30KVHWLCTC8fYwNFS3nJ25Uu7xzg/mt6LtreYjygptp3F9GFUPWCOab8P xE2iP5dcyXaMmyiPiaL/J+kVx7m8o0HNiwzxdn1DWsfeODN0STbcVcYhshjKHQzOjQCi zjo9N2tD10gWbEQMCzd/Fs2eCkXYKTgEaTb8+0sOSWxP6Sh3QC8LBPqdyA1Awtx7vtMX 3bFIN37sgu7m/6UR8YycqdSwTETebH5FAxj62PMsJdgLBdbDeUhX0MFCaNdSPD4dUH0u 9EyMWHkUv5n2CyBMoXqJzhmeEaB7ftobDln4luQOg/ahMn3o32OePum1/C/X1sEcCEvi J+Eg== X-Gm-Message-State: AOAM533fw/+DmS/4+vVv6vTY+FWh6E4i+dxNkpUYOsjyh548br7RPHBx dmGKN/0sekA0y0tOLTdUNZlbNcLydC2hDAMHYfk= X-Google-Smtp-Source: ABdhPJxujkiDiDqSey8xGa8tGJOhl/wcoSF3auaSX6xq2RVAuE/Dqs2TFuW2iEIVRWFbyuCBwT/HU3fK4Z6wdjYmxSY= X-Received: by 2002:a6b:c90f:: with SMTP id z15mr6718749iof.183.1627113929048; Sat, 24 Jul 2021 01:05:29 -0700 (PDT) MIME-Version: 1.0 References: <20210723205840.299280-1-agruenba@redhat.com> <20210723205840.299280-2-agruenba@redhat.com> In-Reply-To: From: =?UTF-8?Q?Andreas_Gr=C3=BCnbacher?= Date: Sat, 24 Jul 2021 10:05:17 +0200 Message-ID: Subject: Re: [PATCH v3 1/7] iov_iter: Introduce fault_in_iov_iter helper To: Al Viro Cc: Andreas Gruenbacher , Linus Torvalds , Christoph Hellwig , "Darrick J. Wong" , Jan Kara , Matthew Wilcox , cluster-devel , Linux FS-devel Mailing List , Linux Kernel Mailing List , ocfs2-devel@oss.oracle.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Sa., 24. Juli 2021 um 03:53 Uhr schrieb Al Viro : > On Fri, Jul 23, 2021 at 10:58:34PM +0200, Andreas Gruenbacher wrote: > > Introduce a new fault_in_iov_iter helper for manually faulting in an iterator. > > Other than fault_in_pages_writeable(), this function is non-destructive. > > > > We'll use fault_in_iov_iter in gfs2 once we've determined that the iterator > > passed to .read_iter or .write_iter isn't in memory. > > Hmm... I suspect that this is going to be much heavier for read access > than the existing variant. Do we ever want it for anything other than > writes? I don't know if it actually is slower when pages need to be faulted in, but I'm fine turning it into a write-only function. Thanks, Andreas