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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 98AC9C12002 for ; Tue, 20 Jul 2021 00:33:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 847E6601FF for ; Tue, 20 Jul 2021 00:33:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241957AbhGSXwV (ORCPT ); Mon, 19 Jul 2021 19:52:21 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:34946 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243971AbhGSXOe (ORCPT ); Mon, 19 Jul 2021 19:14:34 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 9F78822238; Mon, 19 Jul 2021 23:54:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1626738891; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2e30UxNRYI81qzFHTtrwJ5lwISEqhM5uW8QAmbxdFV8=; b=T89awzIfzFFHwjP8S+ng7M6sirVcdMJI1lUO350U/K4A3V/Rvo1aUICYwZOK9hxSOAxGbR Yjh5F3bC5BwPWN7/YgcKNH55iEb8vRuAUCYv3Dr24/9u7iUiOd8LkcghFAgCpIpAG8q1YY UK7+rmUzk3bjyHjZ1SfvSTXQC8rgT80= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1626738891; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2e30UxNRYI81qzFHTtrwJ5lwISEqhM5uW8QAmbxdFV8=; b=Ea5DnS1JyVG2sIt78v1Ii+XDeLaV73dQWYRUXkBQLkdokH3lLP5DZu8V3OsI9r/23Aujr4 Zl56hnPTW5quthBw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 3AD2A13D45; Mon, 19 Jul 2021 23:54:47 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id mo+HN8cQ9mCOGgAAMHmgww (envelope-from ); Mon, 19 Jul 2021 23:54:47 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 From: "NeilBrown" To: "Christoph Hellwig" Cc: "Josef Bacik" , "Christoph Hellwig" , "J. Bruce Fields" , "Chuck Lever" , "Chris Mason" , "David Sterba" , linux-nfs@vger.kernel.org, "Wang Yugui" , "Ulli Horlacher" , linux-btrfs@vger.kernel.org Subject: Re: [PATCH/RFC] NFSD: handle BTRFS subvolumes better. In-reply-to: References: <20210613115313.BC59.409509F4@e16-tech.com>, <20210310074620.GA2158@tik.uni-stuttgart.de>, <162632387205.13764.6196748476850020429@noble.neil.brown.name>, , , <28bb883d-8d14-f11a-b37f-d8e71118f87f@toxicpanda.com>, , , Date: Tue, 20 Jul 2021 09:54:44 +1000 Message-id: <162673888433.4136.7451392112850411713@noble.neil.brown.name> Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, 19 Jul 2021, Christoph Hellwig wrote: > On Thu, Jul 15, 2021 at 02:01:11PM -0400, Josef Bacik wrote: > > This is not a workable solution. It's not a matter of simply tying into > > existing infrastructure, we'd have to completely rework how the VFS deals > > with this stuff in order to be reasonable. And when I brought this up to= Al > > he told me I was insane and we absolutely had to have a different SB for > > every vfsmount, which means we can't use vfsmount for this, which means we > > don't have any other options. Thanks, >=20 > Then fix the problem another way. The problem is known, old and keeps > breaking stuff. Don't paper over it, fix it.=20 Do you have any pointers to other breakage caused by this particular behaviour of btrfs? It would to have all requirements clearly on the table while designing a solution. Thanks, NeilBrown