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,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 B7E23C476E8 for ; Thu, 12 Jul 2018 16:07:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6700B21471 for ; Thu, 12 Jul 2018 16:07:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="FwVlNeUs" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6700B21471 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732354AbeGLQR7 (ORCPT ); Thu, 12 Jul 2018 12:17:59 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:33431 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726912AbeGLQR7 (ORCPT ); Thu, 12 Jul 2018 12:17:59 -0400 Received: by mail-io0-f194.google.com with SMTP id z20-v6so28712951iol.0; Thu, 12 Jul 2018 09:07:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VsP8gzpgcXxlTAZMKVKNU/EFbc+W1xB4jMQVVFPYgOo=; b=FwVlNeUsWqV1vi3rbz6CHySm94wH2kcMFiSJ3p64jBShnXkq8UScP6w59lIgsPGm0o VjsBhUdtc8z/eX9X2+AakSZmEml/r2TnCvfjKh8Wo0SBubrJ6c9ltzVxAjrfhlV2DSEP oK3T0ELoJPLiq0oZ9NkshupSoVZvpw7A8Jc1U= 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=VsP8gzpgcXxlTAZMKVKNU/EFbc+W1xB4jMQVVFPYgOo=; b=ccN+aTiO3fQnUuQiFZMlFHRSUvLvmX/W0mKA+chgZ0cej7XokgAGTuSi4uFD48ICo8 0dkA+nPh3U/Fp+5uKDPGOkcLnariNHUuRaJLS44w9y8uRMfmoNPpXaBuPsqKHJZoevYW GeKbYnp2YWLEWIEgc4h1nCdCh6RDiFxowFNChI6BvdpLPIng4YqHTDwA4wMTVToiQzcW Sedqg5O2E07N5d7ZQjqwwND2wj8oOVVd5DDO1t2SzYwM3GzvdNkIlaPCLfgxRntq3gNM R9wN6AipoM0a/yeqFatFb/Zg8tljlPdDM6GB1SJ4sBZtMnrLN6YkbumYGcOywRBqFoan tQwQ== X-Gm-Message-State: APt69E1Ntqmo+ipF6LiwLras4y+AT34y/1b9LSo0p2gTS+1mepXGdeNv RvtocnrllgpXxmMBf8QrAgJ2PXj2lG3336NuWn0= X-Google-Smtp-Source: AAOMgpfarGiTCA8xDo2UguiPrFkO9f+gV8SBWSv5n2Z7KrICHZTW/56Z15prBVAdwSwFdIIufnCjYucbgxP1qp8e4WQ= X-Received: by 2002:a6b:1502:: with SMTP id 2-v6mr29689467iov.203.1531411667250; Thu, 12 Jul 2018 09:07:47 -0700 (PDT) MIME-Version: 1.0 References: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk> <153126264966.14533.3388004240803696769.stgit@warthog.procyon.org.uk> <686E805C-81F3-43D0-A096-50C644C57EE3@amacapital.net> <22370.1531293761@warthog.procyon.org.uk> <7002.1531407244@warthog.procyon.org.uk> <20180712160030.GV30522@ZenIV.linux.org.uk> In-Reply-To: <20180712160030.GV30522@ZenIV.linux.org.uk> From: Linus Torvalds Date: Thu, 12 Jul 2018 09:07:36 -0700 Message-ID: Subject: Re: [PATCH 24/32] vfs: syscall: Add fsopen() to prepare for superblock creation [ver #9] To: Al Viro Cc: David Howells , Andrew Lutomirski , Linux API , linux-fsdevel , Linux Kernel Mailing List , Jann Horn 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 Thu, Jul 12, 2018 at 9:00 AM Al Viro wrote: > > Wait a sec - that's only a problem if your command contains pointer-chasing > et.al. No. It's a problem if anybody ever does something like "let's have a helper splice thread that uses splice to move data automatically from one buffer to another". And yes, it's something people have wanted. Seriously. I'm putting my foot down. NO COMMANDS IN WRITE DATA! We have made that mistake in the past. Having done stupid things in the past is not an excuse for doing so again. Quite the reverse. Making the same mistake and not learning from your mistakes is the sign of stupidity. So I repeat: write is for data. If you want an action, you do it with ioctl, or you do it with a system call. Linus