From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from frost.carfax.org.uk ([85.119.82.111]:37949 "EHLO frost.carfax.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755433AbeCSNIB (ORCPT ); Mon, 19 Mar 2018 09:08:01 -0400 Date: Mon, 19 Mar 2018 13:07:59 +0000 From: Hugo Mills To: dsterba@suse.cz, "Misono, Tomohiro" , linux-btrfs Subject: Re: [PATCH] btrfs-progs: mkfs: add uuid and otime to ROOT_ITEM of FS_TREE Message-ID: <20180319130759.GD17966@carfax.org.uk> References: <7ca269db-a724-5938-f4d8-b85e893fd558@jp.fujitsu.com> <20180319082010.GC17966@carfax.org.uk> <20180319130222.GE6955@twin.jikos.cz> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="jCrbxBqMcLqd4mOl" In-Reply-To: <20180319130222.GE6955@twin.jikos.cz> Sender: linux-btrfs-owner@vger.kernel.org List-ID: --jCrbxBqMcLqd4mOl Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Mar 19, 2018 at 02:02:23PM +0100, David Sterba wrote: > On Mon, Mar 19, 2018 at 08:20:10AM +0000, Hugo Mills wrote: > > On Mon, Mar 19, 2018 at 05:16:42PM +0900, Misono, Tomohiro wrote: > > > Currently, the top-level subvolume lacks the UUID. As a result, both > > > non-snapshot subvolume and snapshot of top-level subvolume do not have > > > Parent UUID and cannot be distinguisued. Therefore "fi show" of > > > top-level lists all the subvolumes which lacks the UUID in > > > "Snapshot(s)" filed. Also, it lacks the otime information. > > > > > > Fix this by adding the UUID and otime at the mkfs time. As a > > > consequence, snapshots of top-level subvolume now have a Parent UUID and > > > UUID tree will create an entry for top-level subvolume at mount time. > > > This should not cause the problem for current kernel, but user program > > > which relies on the empty Parent UUID may be affected by this change. > > > > Is there any way of adding a UUID to the top level subvol on an > > existing filesystem? It would be helpful not to have to rebuild every > > filesystem in the world to fix this. > > We can do that by a special purpose tool. The easiest way is to set the > uuid on an unmouted filesystem, but as this is a one-time action I hope > this is acceptable. Added to todo, thanks for the suggestion. Sounds good to me. Hugo. -- Hugo Mills | Talking about music is like dancing about hugo@... carfax.org.uk | architecture http://carfax.org.uk/ | PGP: E2AB1DE4 | Frank Zappa --jCrbxBqMcLqd4mOl Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJar7YvAAoJEFheFHXiqx3kjQUP/06ibL3Kw5XYV3VelyaYqoWL cDGqGZ/Eue3t9donG8B6cE8mvy0DGBhpbrBP513KmWwyXsciXZDqgY4JFsY2TKll s/sv2iLE9dp7TJlsyCddUP5wUBcKZikpE8mDeipk37pOrQ8Eo/xQuvXF0xCikjVk VQGhr8pqupSaRIHCdg8hQwrwZNGG8Bi8yd3VQ4GZaxb0pkHlB/Asem96LBkxUAi9 CdI0/V/oVx9AWiWMzdCt9XDaZ+0d5sdSIxjo/gimAoTiLbbMUp+Apg+xhpwr1B1e b4rAoyWEfQgZg73NLW3/gpA8ylifwXY/ZPojZq/1EdHfreegmDkOPteYimf1SaQv aFu5ad9IkFft7fofdTj1fSeyT7z9oj7up+PKYdB3pe/oVUk2o5dOb6JHUjMTX50/ EUvWarfD+CaQZf8qpI+zaxFAXoBTJ8ngEzNGM15nNzpI5iu3Y/uOtVPspJGnnaYv aneeCgd0SG0qwdOVlSmA1+fAqtJ/jSfu0n6sDLzKWG9rPFoHv2iJWlpDi2d7vtRz F+Eebvb0HDryWJ+moOvfASNIDbFmL0CcLHvjc2NPxnXGPSFC9yJhRir1rl34A0l8 AX/qHdJ02iReRXCRiXvkIimovu1+VVJBRAG+vDRzmzsdf1V/XrkX9oZHloGW1nkC 7/LMK6/SLEM5b1lDNy1B =RKiY -----END PGP SIGNATURE----- --jCrbxBqMcLqd4mOl--