[SOLVED] subvolume won't delete

[oldgeek]

I am using Kubuntu 20.04 with BTRFS. I had to do a rollback yesterday, and it went fine except for one little detail. I changed the old @ subvolume to @old, and rolled back to a snapshot of @ taken two days previous. But when I try to delete @old, I get this error message: Could not destroy subvolume/snapshot: directory not empty. Any idea on what might have gone wrong? Everything seems to work as it should.

[jlittle]

What does sudo btrfs su li / say? I'd be looking for another subvolume under @old. F.ex. I have

ID 257 gen 177547 top level   5 path @_eoan_u
ID 286 gen 177535 top level 257 path @_eoan_u/.snapshots

I hope to be deleting @_eoan_u soon, but I'll have to delete @_eoan_u/.snapshots first.

[oldgeek]

It looks like this:

ID 256 gen 80748 top level 5 path @old2
ID 441 gen 1739 top level 256 path @old2/var/lib/portables
ID 442 gen 1740 top level 256 path @old2/var/lib/machines
ID 542 gen 82214 top level 5 path snapshots/@_200429-180302_ro
ID 543 gen 82214 top level 5 path snapshots/@home_200429-180356_ro
ID 573 gen 83524 top level 5 path @
ID 574 gen 83523 top level 5 path @home
ID 596 gen 82214 top level 5 path snapshots/@home_200501-212754
ID 597 gen 82214 top level 5 path snapshots/@_200501-212935

[GreyGeek]

btrfs su delete -C /mnt/snapshots/@old2

[oldgeek]

Error: file doesn't exist

[kubicle]

ID 256 gen 80748 top level 5 path @old2
ID 441 gen 1739 top level 256 path @old2/var/lib/portables
ID 442 gen 1740 top level 256 path @old2/var/lib/machines

Like jlittle suggested, you have two nested subvolumes under @old2 (you can see that in the paths, and it's also shown in the "top level 256"...where 256 refers to the ID of @old2. You cannot delete @old2 if you don't delete the nested subvolumes first.

[Snowhog]

btrfs su delete -C /mnt/snapshots/@old2

Not using BTRFS, but does it have a recursive option?

[oldgeek]

OK, I got rid of the nested subvolumes then deleted @old2. It went successfully. But how did those nested subvolumes get there? Thanks for the help.

[jlittle]

But how did those nested subvolumes get there?

Google suggests that /var/lib/portables is associated with "portable service images".

Portable service images contain an OS file system tree along with systemd(1) unit file information. A service image may be "attached" to the local system. If attached, a set of unit files are copied from the image to the host, and extended with RootDirectory= or RootImage= assignments (in case of service units) pointing to the image file or directory, ensuring the services will run within the file system context of the image.

bash tells me that portablectl is part of the systemd-container package.

Yet another approach to containers on Linux. I suspect you installed this package, or one like it, or one that depends on it or something like it. Speculating, it would make sense that if a container has copies of parts of the OS, to "contain" changes to them, if on a btrfs to use btrfs COW features and have a subvolume for the container or containers.

[kubicle]

Not using BTRFS, but does it have a recursive option?

Not currrently (at least on my version of btrfs-progs), see 'man btrfs-subvolume'. I seem to recall a patch for adding it, but I don't know it's status (whether it was rejected or not yet implemented)

[oshunluvr]

I believe those particular subvolumes are created by the systemd machine manager. You must have been doing some virtual machine or container stuff like Docker or