Re: finding root filesystem of a subvolume?

On Tue, Aug 22, 2017 at 02:23:50PM +0200, Ulli Horlacher wrote:

How do I find the root filesystem of a subvolume?
Example:

root@fex:~# df -T 
Filesystem     Type  1K-blocks      Used Available Use% Mounted on
-              -    1073740800 104244552 967773976  10% /local/.backup/home

   I've never seen the "- -" output from df before. Is this a bind
mount or something?

root@fex:~# btrfs subvolume show /local/.backup/home
/local/.backup/home
        Name:                   home
        uuid:                   f86a2db0-6a82-124f-9a71-1cd4c20fd6fb
        Parent uuid:            ba4d388f-44bf-7b46-b2b8-00e2a9a87181
        Creation time:          2017-08-10 22:19:15
        Object ID:              383
        Generation (Gen):       148
        Gen at creation:        148
        Parent:                 5
        Top Level:              5
        Flags:                  readonly
        Snapshot(s):


I know, the root filesystem is /local, but who can I show it by command?

   Probably in /proc/self/mountinfo -- that should give you the full
set of applied mount options, plus the original source for the mount
(which will be a block device for most filesystem mounts, a path for
bind mounts, or something FS-specific for network filesystems).

   Hugo.

-- 
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