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,URIBL_BLOCKED,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 B9CB1C742D2 for ; Fri, 12 Jul 2019 23:17:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CA562146E for ; Fri, 12 Jul 2019 23:17:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727837AbfGLXRJ (ORCPT ); Fri, 12 Jul 2019 19:17:09 -0400 Received: from smtp02.belwue.de ([129.143.71.87]:48826 "EHLO smtp02.belwue.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727701AbfGLXRJ (ORCPT ); Fri, 12 Jul 2019 19:17:09 -0400 Received: from fex.rus.uni-stuttgart.de (fex.rus.uni-stuttgart.de [129.69.1.129]) by smtp02.belwue.de (Postfix) with SMTP id EF9C7885D for ; Sat, 13 Jul 2019 01:17:05 +0200 (MEST) Date: Sat, 13 Jul 2019 01:17:05 +0200 From: Ulli Horlacher To: linux-btrfs@vger.kernel.org Subject: find subvolume directories Message-ID: <20190712231705.GA16856@tik.uni-stuttgart.de> Mail-Followup-To: linux-btrfs@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org I need to find (all) subvolume directories. I know, btrfs subvolumes root directories have inode #256, but a "find / -inum 256" is horrible slow! Next idea: "btrfs subvolume list /" is really fast, but its output is not always direct usable to find the subvolume directory. Example output on a SUSE system: root@trulla:~# btrfs subvolume list / ID 257 gen 2280099 top level 5 path @ ID 258 gen 2280769 top level 257 path @/home ID 259 gen 2280947 top level 257 path @/opt ID 260 gen 2280098 top level 257 path @/srv ID 261 gen 2280954 top level 257 path @/tmp ID 262 gen 2280187 top level 257 path @/usr/local ID 263 gen 2280099 top level 257 path @/var/crash ID 264 gen 2280949 top level 257 path @/var/log ID 265 gen 2280099 top level 257 path @/var/opt ID 266 gen 2280954 top level 257 path @/var/spool ID 267 gen 2280947 top level 257 path @/var/tmp ID 270 gen 2280222 top level 257 path @/.snapshots ID 453 gen 2280954 top level 270 path @/.snapshots/128/snapshot ID 1235 gen 2280099 top level 257 path @/var/lib/machines ID 12392 gen 2123118 top level 270 path @/.snapshots/1065/snapshot ID 12393 gen 2123120 top level 270 path @/.snapshots/1066/snapshot ID 13273 gen 2176640 top level 270 path @/.snapshots/1089/snapshot ID 13274 gen 2176651 top level 270 path @/.snapshots/1090/snapshot ID 13553 gen 2203681 top level 270 path @/.snapshots/1103/snapshot There is no /@/ directory in the default filesystem because of: root@trulla:/# stat /@/.snapshots/128/snapshot stat: cannot stat '/@/.snapshots/128/snapshot': No such file or directory root@trulla:~# btrfs subvolume get-default / ID 453 gen 2280954 top level 270 path @/.snapshots/128/snapshot root@trulla:/# mount | grep " / " /dev/sda2 on / type btrfs (rw,relatime,space_cache,subvolid=453,subvol=/@/.snapshots/128/snapshot) On this particular system I could remove "@" from the subvolume path to get the subvolume directory: root@trulla:/# stat /.snapshots/128/snapshot File: '/.snapshots/128/snapshot' Size: 198 Blocks: 0 IO Block: 4096 directory Device: 27h/39d Inode: 256 Links: 1 Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2019-07-13 01:03:08.543830085 +0200 Modify: 2019-07-13 01:03:37.336445461 +0200 Change: 2019-07-13 01:03:37.336445461 +0200 Birth: - But what if a btrfs filesystem does not have a toplevel /@/ directory, but anything else, like /this/is/my/top/directory ? Will be the first output line of "btrfs subvolume list /" always look like ID 257 gen 2280099 top level 5 path this/is/my/top/directory ? -- Ullrich Horlacher Server und Virtualisierung Rechenzentrum TIK Universitaet Stuttgart E-Mail: horlacher@tik.uni-stuttgart.de Allmandring 30a Tel: ++49-711-68565868 70569 Stuttgart (Germany) WWW: http://www.tik.uni-stuttgart.de/ REF:<20190712231705.GA16856@tik.uni-stuttgart.de>