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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 403A9C4646D for ; Sat, 11 Aug 2018 02:17:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00979219C8 for ; Sat, 11 Aug 2018 02:17:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 00979219C8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ZenIV.linux.org.uk 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 S1727416AbeHKEtv (ORCPT ); Sat, 11 Aug 2018 00:49:51 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:60288 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727304AbeHKEtv (ORCPT ); Sat, 11 Aug 2018 00:49:51 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.87 #1 (Red Hat Linux)) id 1foJSi-0008Sq-Dq; Sat, 11 Aug 2018 02:17:04 +0000 Date: Sat, 11 Aug 2018 03:17:04 +0100 From: Al Viro To: "Eric W. Biederman" Cc: David Howells , John Johansen , Tejun Heo , selinux@tycho.nsa.gov, Paul Moore , Li Zefan , linux-api@vger.kernel.org, apparmor@lists.ubuntu.com, Casey Schaufler , fenghua.yu@intel.com, Greg Kroah-Hartman , Eric Biggers , linux-security-module@vger.kernel.org, Tetsuo Handa , Johannes Weiner , Stephen Smalley , tomoyo-dev-en@lists.sourceforge.jp, cgroups@vger.kernel.org, torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y. Ts'o" , Miklos Szeredi Subject: Re: BUG: Mount ignores mount options Message-ID: <20180811021704.GE6515@ZenIV.linux.org.uk> References: <153313703562.13253.5766498657900728120.stgit@warthog.procyon.org.uk> <87d0uqpba5.fsf@xmission.com> <20180810151606.GA6515@ZenIV.linux.org.uk> <87pnypiufr.fsf@xmission.com> <20180811015815.GD6515@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180811015815.GD6515@ZenIV.linux.org.uk> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 11, 2018 at 02:58:15AM +0100, Al Viro wrote: > On Fri, Aug 10, 2018 at 08:05:44PM -0500, Eric W. Biederman wrote: > > > All I proposed was that we distinguish between a first mount and an > > additional mount so that userspace knows the options will be ignored. > > For pity sake, just what does it take to explain to you that your > notions of "first mount" and "additional mount" ARE HEAVILY FS-DEPENDENT > and may depend upon the pieces of state userland (especially in container) > simply does not have? > > One more time, slowly: > > mount -t nfs4 wank.example.org:/foo/bar /mnt/a > mount -t nfs4 wank.example.org:/baz/barf /mnt/b > > yield the same superblock. Is anyone who mounts something over NFS > required to know if anybody else has mounted something from the same > server, and if so how the hell are they supposed to find that out, > so that they could decide whether they are creating the "first" or > "additional" mount, whatever that might mean in this situation? > > And how, kernel-side, is that supposed to be handled by generic code > of any description? > > While we are at it, > mount -t nfs4 wank.example.org:/foo/bar -o wsize=16384 /mnt/c > is *NOT* the same superblock as the previous two. s/as the previous two/as in the previous two cases/, that is - the first two examples yield one superblock, this one - another.