Re: workaround for buggy GNU df

[Ulli Horlacher <framstag@rus.uni-stuttgart.de>]

On Fri 2024-06-21 (08:57), Ulli Horlacher wrote:
> 
> The GNU tool df does not work correctly on btrfs, example:
> 
> root@fex:/test/test/test# df -T phoon.png
> Filesystem     Type 1K-blocks     Used Available Use% Mounted on
> -              -     67107840 16458828  47946692  26% /test/test
> 
> root@fex:/test/test/test# grep /test /proc/mounts || echo nope
> nope
> 
> The mountpoint is wrong, the kernel knows the truth.
> 
> Therefore I have written fst:
> 
> root@fex:/test/test/test# fst phoon.png
> path:       /test/test/test/phoon.png
> mountpoint: /
> subvolume:  /test/test
> volume:     /dev/sdd1
> filesystem: btrfs
> 
> 
> https://fex.belwue.de/linuxtools/index.html#fst

I have now extended fst to fstat :

framstag@fex:/local/test/.snapshot/.latest/test: fstat zz
      File: "zz"
 Directory: /local/test/.snapshot/2025-09-05_1917.test/test
      Size: 40 B
Allocation: 4 kB
      Type: regular file
      Mode: rw-r--r--
       UID: root
       GID: root
    Device: /dev/sde1
   FS-Type: btrfs
Mountpoint: /local (rw)
 Subvolume: /local/test/.snapshot/2025-09-05_1917.test (ro)
     Inode: 5107
     Links: 1
    Access: 2025-06-18 10:22:51
    Modify: 2024-05-20 02:02:08
    Change: 2024-06-03 10:58:22
     Birth: 2024-06-03 10:58:22

fstat also shows the btrfs subvolume and its rw/ro status.


framstag@fex:/local/test/.snapshot/.latest/test: df --version
df (GNU coreutils) 9.4

framstag@fex:/local/test/.snapshot/.latest/test: df -T .
Filesystem     Type  1K-blocks     Used Available Use% Mounted on
-              -    1073740800 82884012 989711428   8% /local/test/.snapshot/2025-09-05_1917.test

framstag@fex:/local/test/.snapshot/.latest/test: grep /local /proc/mounts
/dev/sde1 /local btrfs rw,relatime,space_cache,user_subvol_rm_allowed,subvolid=5,subvol=/ 0 0

==> df cannot handle btrfs!


https://fex.belwue.de/fstools/fstat.html

-- 
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:    https://www.tik.uni-stuttgart.de/
REF:<20240621065709.GA598391@tik.uni-stuttgart.de>