From owner-svn-src-head@freebsd.org Sun Oct 25 22:58:14 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 AC94A45B606; Sun, 25 Oct 2020 22:58:14 +0000 (UTC) (envelope-from cy.schubert@cschubert.com) Received: from smtp-out-so.shaw.ca (smtp-out-so.shaw.ca [64.59.136.139]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "Client", Issuer "CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4CKD051V8Kz4dbL; Sun, 25 Oct 2020 22:58:12 +0000 (UTC) (envelope-from cy.schubert@cschubert.com) Received: from spqr.komquats.com ([70.67.229.168]) by shaw.ca with ESMTPA id WoxlkNclFktFkWoxmktyNa; Sun, 25 Oct 2020 16:58:11 -0600 X-Authority-Analysis: v=2.4 cv=NYRYa0P4 c=1 sm=1 tr=0 ts=5f960303 a=7AlCcx2GqMg+lh9P3BclKA==:117 a=7AlCcx2GqMg+lh9P3BclKA==:17 a=xqWC_Br6kY4A:10 a=kj9zAlcOel0A:10 a=afefHYAZSVUA:10 a=6I5d2MoRAAAA:8 a=YxBL1-UpAAAA:8 a=EkcXrb_YAAAA:8 a=xZtxMNEC6JyLLf0W19AA:9 a=CjuIK1q_8ugA:10 a=IjZwj45LgO3ly-622nXo:22 a=Ia-lj3WSrqcvXOmTRaiG:22 a=LK5xJRSDVpKd5WXXoEvA:22 Received: from slippy.cwsent.com (slippy [IPv6:fc00:1:1:1::5b]) by spqr.komquats.com (Postfix) with ESMTPS id B0E3693E; Sun, 25 Oct 2020 15:58:07 -0700 (PDT) Received: from slippy (localhost [127.0.0.1]) by slippy.cwsent.com (8.16.1/8.16.1) with ESMTP id 09PMw7wK009643; Sun, 25 Oct 2020 15:58:07 -0700 (PDT) (envelope-from Cy.Schubert@cschubert.com) Message-Id: <202010252258.09PMw7wK009643@slippy.cwsent.com> X-Mailer: exmh version 2.9.0 11/07/2018 with nmh-1.7.1 Reply-to: Cy Schubert From: Cy Schubert X-os: FreeBSD X-Sender: cy@cwsent.com X-URL: http://www.cschubert.com/ To: Cy Schubert , Oliver Pinter , "src-committers@freebsd.org" , "svn-src-all@freebsd.org" , "svn-src-head@freebsd.org" Subject: Re: svn commit: r367038 - head/sbin/mount_nullfs In-reply-to: <20201025213509.GA1671@brick> References: <202010251409.09PE91aS001781@repo.freebsd.org> <202010251417.09PEH6tE003403@slippy.cwsent.com> <20201025213509.GA1671@brick> Comments: In-reply-to Edward Tomasz Napierala message dated "Sun, 25 Oct 2020 21:35:09 -0000." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 25 Oct 2020 15:58:07 -0700 X-CMAE-Envelope: MS4xfB/EU3NlswQp11K5faTDjga4SgmYOe4TnBRu9P9kQjvIuzQIr5taft+UF0sOC65MN3xU6CRLX+9mVCg+KvL0id27uA870V4yx9fysNR+TK3hzybRBsk0 bWyfu7R9zjpQUHnUM1kWakdRfAyZGcG4tn8Zw8maZW/q7wlEJe+ABNd2E00F4/A1+vy9xHepfs04hNfUTpesgFxke+gQavBBwTaxHjXGFaH2hYMnwCgfiNb+ sxi+DWAuN4KkVqWzwIJdorrobBkXHtEn6tTFb0gBi2XolxveLDzSXfbNJPs2+a3vp5vGCEc861PC/mF+q/wcUA== X-Rspamd-Queue-Id: 4CKD051V8Kz4dbL X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of cy.schubert@cschubert.com has no SPF policy when checking 64.59.136.139) smtp.mailfrom=cy.schubert@cschubert.com X-Spamd-Result: default: False [-1.25 / 15.00]; HAS_REPLYTO(0.00)[Cy.Schubert@cschubert.com]; TO_DN_EQ_ADDR_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; MV_CASE(0.50)[]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_COUNT_THREE(0.00)[4]; NEURAL_HAM_SHORT(-0.59)[-0.586]; FREEMAIL_TO(0.00)[cschubert.com,gmail.com,freebsd.org]; RECEIVED_SPAMHAUS_PBL(0.00)[70.67.229.168:received]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; ASN(0.00)[asn:6327, ipnet:64.59.128.0/20, country:CA]; MIME_TRACE(0.00)[0:+]; RCVD_IN_DNSWL_LOW(-0.10)[64.59.136.139:from]; RCVD_TLS_LAST(0.00)[]; ARC_NA(0.00)[]; REPLYTO_EQ_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; NEURAL_HAM_MEDIUM(-0.96)[-0.960]; NEURAL_HAM_LONG(-1.00)[-1.005]; TAGGED_RCPT(0.00)[]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[cschubert.com: no valid DMARC record]; AUTH_NA(1.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; R_SPF_NA(0.00)[no SPF record]; RWL_MAILSPIKE_VERYGOOD(0.00)[64.59.136.139:from]; MAILMAN_DEST(0.00)[svn-src-all,svn-src-head] 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: Sun, 25 Oct 2020 22:58:14 -0000 In message <20201025213509.GA1671@brick>, Edward Tomasz Napierala writes: > On 1025T0717, Cy Schubert wrote: > > In message c > > om> > > , Oliver Pinter writes: > > > On Sunday, October 25, 2020, Edward Tomasz Napierala > > > wrote: > > > > > > > Author: trasz > > > > Date: Sun Oct 25 14:09:00 2020 > > > > New Revision: 367038 > > > > URL: https://svnweb.freebsd.org/changeset/base/367038 > > > > > > > > Log: > > > > Remove the check that prevents creating "loops" from mount_nullfs(8). > > > > > > > > > > > The simple question is: why? > > > > I was about to ask that myself. > > > > The why is usually more important than the how. > > Two reasons. > > First, from what I can tell this is an artificial limitation which serves > no purpose. I thought it was to prevent some kind of deadlock between > vnodes, so I asked kib@, and he mentioned removing that very limitation > from the kernel code; thus, it looks to me like a historical leftover. > > Second, I've stumbled upon this when trying to nullfs-mount '/' on > '/compat/ubuntu/bsd/', which would be useful for autochroot functionality, > when (or if) it becomes a thing. Thanks. -- Cheers, Cy Schubert FreeBSD UNIX: Web: https://FreeBSD.org NTP: Web: https://nwtime.org The need of the many outweighs the greed of the few.