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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6ADEBC25B48 for ; Fri, 27 Oct 2023 05:44:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231177AbjJ0Fog (ORCPT ); Fri, 27 Oct 2023 01:44:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229590AbjJ0Fof (ORCPT ); Fri, 27 Oct 2023 01:44:35 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BB321A7; Thu, 26 Oct 2023 22:44:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=tJIaOwEddcdYLTVKEZH1EeDVU5DzYIlN4t/E6prxOjk=; b=VbVJvjE0VhdfX/aZ23V+vUXiX7 AHkXChdvSiIlFUCGKayf3ZakUBkBerD4KBsbej2qi9C+rzanKR3LXfoqxJtYHQs+Z8nQf1yz0IoF4 gUPu0+lSbY3HqDbkyYVDcl4pTPTwe5BDzX/OqZlYLTyJfOhLFM2Evaaj0pt1IkDRXuOqgz6ozP5S1 hzs6UHr7gbUGp1rYlHuZuVY3ZToMsEZGXXAbloMWE7AAkrXApMQRgThHgQ/4/0KwAfWHIzm9TR7FL 9jtRn7rcnien1OoPCslLQjaJ9jV/FeoBx5XZpri29Wzv7ZI7LHLpvcyGH2JYqxkItM/QxPWSMwTbU bHJw5mNg==; Received: from hch by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1qwFdy-00FdCR-0z; Fri, 27 Oct 2023 05:44:26 +0000 Date: Thu, 26 Oct 2023 22:44:26 -0700 From: Christoph Hellwig To: Jan Kara Cc: Christoph Hellwig , Amir Goldstein , Christian Brauner , Chris Mason , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 0/3] fanotify support for btrfs sub-volumes Message-ID: References: <20231025135048.36153-1-amir73il@gmail.com> <20231025170445.qks7etxtwivyqz22@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231025170445.qks7etxtwivyqz22@quack3> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, Oct 25, 2023 at 07:04:45PM +0200, Jan Kara wrote: > Well, this is the discussion how btrfs should be presenting its subvolumes > to VFS / userspace, isn't it? Yes. Which we've pressured to resolve forever, but it's been ignored. > I never dived into that too closely but as > far as I remember it was discussed to death without finding an acceptable > (to all parties) solution? I guess having a different fsid per subvolume > makes sense (and we can't change that given it is like that forever even if > we wanted). Having different subvolumes share one superblock is more > disputable but there were reasons for that as well. So I'm not sure how you > imagine to resolve this... We need to solve this out kernel wide, and right now the kernel doesn't support different dev_t / fsids inside a single file syste at all. SuSE hacks around that badly for limited user interfaces with the horrible get_inode_dev method they've added, but this has been rejected upstream for good reason. What this series does is to add another limited version of this through the backdoor.