From owner-svn-src-head@freebsd.org Sat Sep 19 23:32:47 2020 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id CE5783F2755; Sat, 19 Sep 2020 23:32:47 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4Bv6SZ6mG9z4fH1; Sat, 19 Sep 2020 23:32:46 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.16.1/8.16.1) with ESMTPS id 08JNWWrG008110 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Sun, 20 Sep 2020 02:32:35 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua 08JNWWrG008110 Received: (from kostik@localhost) by tom.home (8.16.1/8.16.1/Submit) id 08JNWWGo008109; Sun, 20 Sep 2020 02:32:32 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Sun, 20 Sep 2020 02:32:32 +0300 From: Konstantin Belousov To: Rick Macklem Cc: Alan Somers , "src-committers@freebsd.org" , "svn-src-all@freebsd.org" , "svn-src-head@freebsd.org" Subject: Re: svn commit: r365643 - head/bin/cp Message-ID: <20200919233232.GC94807@kib.kiev.ua> References: <202009112049.08BKnavL032212@repo.freebsd.org> <20200911214327.GY94807@kib.kiev.ua> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FORGED_GMAIL_RCVD,FREEMAIL_FROM, NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on tom.home X-Rspamd-Queue-Id: 4Bv6SZ6mG9z4fH1 X-Spamd-Bar: / Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=gmail.com (policy=none); spf=softfail (mx1.freebsd.org: 2001:470:d5e7:1::1 is neither permitted nor denied by domain of kostikbel@gmail.com) smtp.mailfrom=kostikbel@gmail.com X-Spamd-Result: default: False [-0.67 / 15.00]; ARC_NA(0.00)[]; TO_DN_EQ_ADDR_SOME(0.00)[]; DMARC_POLICY_SOFTFAIL(0.10)[gmail.com : No valid SPF, No valid DKIM,none]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_FROM(0.00)[gmail.com]; NEURAL_HAM_LONG(-0.16)[-0.160]; MIME_GOOD(-0.10)[text/plain]; HAS_XAW(0.00)[]; NEURAL_HAM_MEDIUM(-0.47)[-0.473]; R_SPF_SOFTFAIL(0.00)[~all:c]; RCPT_COUNT_FIVE(0.00)[5]; TO_MATCH_ENVRCPT_SOME(0.00)[]; NEURAL_HAM_SHORT(-0.04)[-0.042]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:6939, ipnet:2001:470::/32, country:US]; MIME_TRACE(0.00)[0:+]; MAILMAN_DEST(0.00)[svn-src-all,svn-src-head]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 19 Sep 2020 23:32:47 -0000 On Sat, Sep 19, 2020 at 11:18:56PM +0000, Rick Macklem wrote: > Alan Somers wrote: > >On Fri, Sep 11, 2020 at 3:52 PM Rick Macklem > wrote: > >Konstantin Belousov wrote: > >>On Fri, Sep 11, 2020 at 08:49:36PM +0000, Alan Somers wrote: > >>> Author: asomers > >>> Date: Fri Sep 11 20:49:36 2020 > >>> New Revision: 365643 > >>> URL: https://svnweb.freebsd.org/changeset/base/365643 > >>> > >>> Log: > >>> cp: fall back to read/write if copy_file_range fails > >>> > >>> Even though copy_file_range has a file-system agnostic version, it still > >>> fails on devfs (perhaps because the file descriptor is non-seekable?) In > >>> that case, fallback to old-fashioned read/write. Fixes > >>> "cp /dev/null /tmp/null" > >> > >>Devices are seekable. > >> > >>The reason for EINVAL is that vn_copy_file_range() checks that both in and out > >>vnodes are VREG. For devfs, they are VCHR. > > > >I coded the syscall to the Linux man page, which states that EINVAL is returned > >if either fd does not refer to a regular file. > >Having said that, I do not recall testing the VCHR case under Linux. (ie. It might > >actually work and the man page turns out to be incorrect?) > > > >I will test this case under Linux when I get home next week, rick > I'll admit I haven't tested this in Linux to see if they do return EINVAL. > > >Since there's no standard, I think it's fine for us to support devfs if possible. > 1 - I think this is a good question for a mailing list like freebsd-current@. > 2 - I see Linux as the de-facto standard these days and consider POSIX no > longer relevant, but that's just mho. > 3 - For NFSv4.2, the Copy operation will fail for non-regular files, so if you > do this, you will need to handle the fall-back to using the generic code. > (Should be doable, but you need to be aware of this case.) > > Having said the above, it is up to the "collective" and not me and, as such, > I suggest #1, to see whether others think doing a non-Linux compatible > version makes sense for FreeBSD? I believe that allowing devfs nodes for vn_copy_file() is not very good idea. For /dev/null driver returns EOF, but think about real devices or even better, /dev/zero that never EOF its output. Is vn_copy_file() interruptible ? I think not. So if insane range is specified, we have unstoppable copier that fills the disk (at best).