From: Ulli Horlacher <framstag@rus.uni-stuttgart.de>
To: linux-btrfs@vger.kernel.org
Subject: find subvolume directories
Date: Sat, 13 Jul 2019 01:17:05 +0200 [thread overview]
Message-ID: <20190712231705.GA16856@tik.uni-stuttgart.de> (raw)
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>
next reply other threads:[~2019-07-12 23:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-12 23:17 Ulli Horlacher [this message]
2019-07-13 3:59 ` find subvolume directories Andrei Borzenkov
2019-07-13 8:27 ` Ulli Horlacher
2019-07-13 11:10 ` Andrei Borzenkov
2019-07-13 11:28 ` Ulli Horlacher
2019-07-13 15:08 ` Andrei Borzenkov
2019-07-15 13:22 ` Piotr Szymaniak
2019-07-15 22:40 ` Ulli Horlacher
2019-07-15 23:58 ` [RFC] a standard user-friendly way to find a snapshot in nested subvolumes [was: find subvolume directories] Nicholas D Steeves
2019-07-16 0:41 ` Ulli Horlacher
2019-07-15 11:39 ` find subvolume directories Ulli Horlacher
2019-07-15 11:33 ` Ulli Horlacher
2019-07-16 11:04 ` Ulli Horlacher
2019-07-18 12:00 ` Axel Burri
2019-07-18 17:48 ` Andrei Borzenkov
2019-07-22 12:36 ` Axel Burri
2019-07-20 9:27 ` Ulli Horlacher
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