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 2A533C4338F for ; Sun, 15 Aug 2021 21:54:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 171606139E for ; Sun, 15 Aug 2021 21:54:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231355AbhHOVyh (ORCPT ); Sun, 15 Aug 2021 17:54:37 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:48370 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230077AbhHOVyg (ORCPT ); Sun, 15 Aug 2021 17:54:36 -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-out2.suse.de (Postfix) with ESMTPS id 01A8F1FE49; Sun, 15 Aug 2021 21:54:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1629064445; 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=56y/Def2nMkNp3coJSSqIPb+5JvFWXIr2Sjjvt/Soug=; b=b7BNsdnYAibTL13hBupU22Jz8E+9hFXD6OKZ62SAstQ2NLSe/9wf3WRT1tCZMPgb6LZjjj iEfYGgQJvtUvG8Y3l7y5sChekJNUZBJCWUL0veYdV9VsGNL1L1eyVLcEmHpDQJ/gfBrxzc k5C2K72jhV2T5ysiYI598FARvXHeonw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1629064445; 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=56y/Def2nMkNp3coJSSqIPb+5JvFWXIr2Sjjvt/Soug=; b=a0fj8xB25GCYDqR5DEM5VQwPIcNGQQYE+hfqum36UfX3RV+KnpLQxtGbaGEHaIOsubvKpm D6Ov5v2CKti8vfCg== 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 90AEB147F9; Sun, 15 Aug 2021 21:54:01 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id GcjcE/mMGWFuZwAAMHmgww (envelope-from ); Sun, 15 Aug 2021 21:54:01 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 From: "NeilBrown" To: kreijack@inwind.it Cc: "Roman Mamedov" , "Christoph Hellwig" , "Josef Bacik" , "J. Bruce Fields" , "Chuck Lever" , "Chris Mason" , "David Sterba" , "Alexander Viro" , linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH] VFS/BTRFS/NFSD: provide more unique inode number for btrfs export In-reply-to: References: <162742539595.32498.13687924366155737575.stgit@noble.brown>, <162881913686.1695.12479588032010502384@noble.neil.brown.name>, , <20210816003505.7b3e9861@natsu>, Date: Mon, 16 Aug 2021 07:53:58 +1000 Message-id: <162906443866.1695.6446438554332029261@noble.neil.brown.name> Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, 16 Aug 2021, kreijack@inwind.it wrote: > On 8/15/21 9:35 PM, Roman Mamedov wrote: > > On Sun, 15 Aug 2021 09:39:08 +0200 > > Goffredo Baroncelli wrote: > >=20 > >> I am sure that it was discussed already but I was unable to find any tra= ck > >> of this discussion. But if the problem is the collision between the inode > >> number of different subvolume in the nfd export, is it simpler if the ex= port > >> is truncated to the subvolume boundary ? It would be more coherent with = the > >> current behavior of vfs+nfsd. > >=20 > > See this bugreport thread which started it all: > > https://www.spinics.net/lists/linux-btrfs/msg111172.html > >=20 > > In there the reporting user replied that it is strongly not feasible for = them > > to export each individual snapshot. >=20 > Thanks for pointing that. >=20 > However looking at the 'exports' man page, it seems that NFS has already an > option to cover these cases: 'crossmnt'. >=20 > If NFSd detects a "child" filesystem (i.e. a filesystem mounted inside an a= lready > exported one) and the "parent" filesystem is marked as 'crossmnt', the cli= ent mount > the parent AND the child filesystem with two separate mounts, so there is n= ot problem of inode collision. As you acknowledged, you haven't read the whole back-story. Maybe you should. https://lore.kernel.org/linux-nfs/20210613115313.BC59.409509F4@e16-tech.com/ https://lore.kernel.org/linux-nfs/162848123483.25823.15844774651164477866.stg= it@noble.brown/ https://lore.kernel.org/linux-btrfs/162742539595.32498.13687924366155737575.s= tgit@noble.brown/ The flow of conversation does sometimes jump between threads. I'm very happy to respond you questions after you've absorbed all that. NeilBrown