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=-2.2 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 05B22CA90AF for ; Wed, 13 May 2020 12:41:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D863D20659 for ; Wed, 13 May 2020 12:41:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731649AbgEMMlr convert rfc822-to-8bit (ORCPT ); Wed, 13 May 2020 08:41:47 -0400 Received: from james.kirk.hungrycats.org ([174.142.39.145]:48452 "EHLO james.kirk.hungrycats.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726081AbgEMMlr (ORCPT ); Wed, 13 May 2020 08:41:47 -0400 Received: by james.kirk.hungrycats.org (Postfix, from userid 1002) id E797C6C00B8; Wed, 13 May 2020 08:41:46 -0400 (EDT) Date: Wed, 13 May 2020 08:41:46 -0400 From: Zygo Blaxell To: "miguel@rozsas.eng.br" Cc: linux-btrfs@vger.kernel.org Subject: Re: How to find the parent folder of a sub-volume ? Message-ID: <20200513124146.GB10769@hungrycats.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, May 12, 2020 at 02:17:19PM -0300, miguel@rozsas.eng.br wrote: > Hi there ! > > root@fenix:/home/miguel# btrfs --version > btrfs-progs v5.2.1 > root@fenix:/home/miguel# btrfs subvolume list /home/miguel/tmp/ > ID 265 gen 20670 top level 5 path miguel > ID 266 gen 23573 top level 265 path miguel/Documentos > ID 267 gen 23575 top level 265 path miguel/Downloads > ID 269 gen 23537 top level 265 path miguel/Misc > ID 270 gen 23522 top level 265 path miguel/Musica > ID 271 gen 23526 top level 265 path miguel/ProgramasRFB > ID 272 gen 23574 top level 265 path miguel/tmp > ID 273 gen 23509 top level 265 path miguel/Videos > ID 274 gen 23574 top level 265 path miguel/R > ID 275 gen 23557 top level 265 path miguel/Imagens > ID 302 gen 23507 top level 265 path miguel/Tech > ID 595 gen 23517 top level 265 path miguel/src/UPSData > ID 596 gen 23510 top level 265 path miguel/bin/UPSData > root@fenix:/home/miguel# > > How to find the parent folder (root tree?) of the above sub-volumes ? > On this parent folder I expect to see the above sub-folders as regular folders. If you want to have access to the root subvol, the easiest way is to just mount it: mkdir /mnt/root-subvol mount /dev/... /mnt/root-subvol -o subvol= (note the parameter "subvol" is set to ""). A btrfs subvol can be mounted multiple times in multiple places, so each application that requires the root subvol can simply mount its own. There is no general solution for accessing the root subvol through an arbitrary existing mountpoint because the root subvol might not be accessible to a process (e.g. chroot, different namespace, etc) or might not be mounted at all (e.g. mount -o subvol=miguel /dev/... /path/...). > best regards,