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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 356F0C4363A for ; Tue, 27 Oct 2020 09:29:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A968B22265 for ; Tue, 27 Oct 2020 09:29:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SljjII7e" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2895590AbgJ0J3z (ORCPT ); Tue, 27 Oct 2020 05:29:55 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:60032 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2895588AbgJ0J3y (ORCPT ); Tue, 27 Oct 2020 05:29:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603790993; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=feIJOART/ZjbjgTvLv37NEKK+uAf07iUjckzKK2mLvo=; b=SljjII7eLt3VvPPy7LrOzyhNOMvKwfDe39zTJQeFjFv6DAvjMXXWeNFSBL/jJlhW7dgAhp rdB7xXDhGlPBthd/sIqprsUXB892cotkW/QF8dlEX7Y5ujh70dz+mddPE36jbnxul92x2j TT0bI44lVn8WAcyZMLbuhOQq+l9cm50= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-190-8oJbH0wQNXae1a0bKDAYWw-1; Tue, 27 Oct 2020 05:29:49 -0400 X-MC-Unique: 8oJbH0wQNXae1a0bKDAYWw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8DC62186DD25; Tue, 27 Oct 2020 09:29:47 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-70.rdu2.redhat.com [10.10.120.70]) by smtp.corp.redhat.com (Postfix) with ESMTP id 89DA75C1BD; Tue, 27 Oct 2020 09:29:45 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20200827150030.282762-3-hch@lst.de> References: <20200827150030.282762-3-hch@lst.de> <20200827150030.282762-1-hch@lst.de> To: Christoph Hellwig Cc: dhowells@redhat.com, Linus Torvalds , Al Viro , Michael Ellerman , x86@kernel.org, Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 02/10] fs: don't allow splice read/write without explicit ops MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3088367.1603790984.1@warthog.procyon.org.uk> Date: Tue, 27 Oct 2020 09:29:44 +0000 Message-ID: <3088368.1603790984@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Christoph Hellwig wrote: > default_file_splice_write is the last piece of generic code that uses > set_fs to make the uaccess routines operate on kernel pointers. It > implements a "fallback loop" for splicing from files that do not actually > provide a proper splice_read method. The usual file systems and other > high bandwith instances all provide a ->splice_read, so this just removes > support for various device drivers and procfs/debugfs files. If splice > support for any of those turns out to be important it can be added back > by switching them to the iter ops and using generic_file_splice_read. Hmmm... this causes the copy_file_range() syscall to fail with EINVAL in some places where before it used to work. For my part, it causes the generic/112 xfstest to fail with afs, but there may be other places. Is this a regression we need to fix in the VFS core? Or is it something we need to fix in xfstests and assume userspace will fallback to doing it itself? David