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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 6FFFFC2BA17 for ; Mon, 6 Apr 2020 18:46:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49EBA206B8 for ; Mon, 6 Apr 2020 18:46:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726399AbgDFSq1 (ORCPT ); Mon, 6 Apr 2020 14:46:27 -0400 Received: from fieldses.org ([173.255.197.46]:52306 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725876AbgDFSq1 (ORCPT ); Mon, 6 Apr 2020 14:46:27 -0400 Received: by fieldses.org (Postfix, from userid 2815) id B62FB1C7B; Mon, 6 Apr 2020 14:46:26 -0400 (EDT) Date: Mon, 6 Apr 2020 14:46:26 -0400 From: "J. Bruce Fields" To: Linus Torvalds Cc: Karel Zak , Lennart Poettering , Miklos Szeredi , Ian Kent , David Howells , Christian Brauner , Al Viro , dray@redhat.com, Miklos Szeredi , Steven Whitehouse , Jeff Layton , andres@anarazel.de, keyrings@vger.kernel.org, linux-fsdevel , Linux Kernel Mailing List , Aleksa Sarai Subject: Re: Upcoming: Notifications, FS notifications and fsinfo() Message-ID: <20200406184626.GE2147@fieldses.org> References: <36e45eae8ad78f7b8889d9d03b8846e78d735d28.camel@themaw.net> <27994c53034c8f769ea063a54169317c3ee62c04.camel@themaw.net> <20200403111144.GB34663@gardel-login> <20200403151223.GB34800@gardel-login> <20200403203024.GB27105@fieldses.org> <20200406091701.q7ctdek2grzryiu3@ws.net.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 06, 2020 at 09:34:08AM -0700, Linus Torvalds wrote: > On Mon, Apr 6, 2020 at 2:17 AM Karel Zak wrote: > > > > On Fri, Apr 03, 2020 at 04:30:24PM -0400, J. Bruce Fields wrote: > > > > > > nfs-utils/support/misc/mountpoint.c:check_is_mountpoint() stats the file > > > and ".." and returns true if they have different st_dev or the same > > > st_ino. Comparing mount ids sounds better. > > > > BTW, this traditional st_dev+st_ino way is not reliable for bind mounts. > > For mountpoint(1) we search the directory in /proc/self/mountinfo. > > These days you should probably use openat2() with RESOLVE_NO_XDEV. > > No need for any mountinfo or anything like that. Just look up the > pathname and say "don't cross mount-points", and you'll get an error > if it's a mount crossing lookup. OK, I can't see why that wouldn't work, thanks. --b. > > So this kind of thing is _not_ an argument for another kernel querying > interface. We got a new (and better) model for a lot of this. > > Linus