Re: Deleted snapshots stay in squota, mayube because of bees?

[Boris Burkov <boris@bur.io>]

On Wed, Apr 22, 2026 at 10:10:10AM -0700, Marc MERLIN wrote:
> Hi Boris,
> 
> I noticed another issue, when I do a btrfs send to this volume
> which was created cleanly from scratch with squota, if I have
> an incomplete btrfs receive subvolume (copy failed half way),
> when I delete it, it does from
> <under deletion> to <squota space holder>.
> You'll notice I have now two <squota space holder> which just so happen
> to be 297.04MiB each.
> 
> I do run bees, so there is a very small chance bees took data from
> debian64 and dupedd it against another subvolume and then can't delete
> all the data, but in this example backup/debian64_kodi_ro.20260327_10:11:40
> was last, so any duped data should have been duped against a previous
> snapshot, and ideally not leave leftover squota data after deletion,
> unless bees somehow is making those references the other way around
> and the new copy becomes the master copy for squota?
> 
> But even then, it looks a bit weird that now I have two
> 0/263        297.04MiB    297.04MiB   <squota space holder>
> 0/269        287.84MiB    287.84MiB   <squota space holder>
> of almost the same space
> 
> Is that still working as intended and I don't quite grasp how?

We can't delete a qgroup that still has usage, and subvols own their
extents forever. So assuming no bugs, this means that some other
subvolume is referencing the extents originally owned by these
subvolumes. I agree that this sounds relatively unlikely for a failed
receive target you immediately deleted.

I believe that btrfs check has the ability to reconcile the on-disk
squota owner_refs with the on-disk qgroup values and find any real
discrepancies. So if you run that (without repair please :) ), and it
doesn't complain, I think you do have some legit sharing happening, and
you can try to track that down more directly.

> 
> gargamel:/mnt/btrfs_pool2/backup# btrfs qgroup show .
> Qgroupid    Referenced    Exclusive   Path 
> --------    ----------    ---------   ---- 
> 0/5            1.61GiB      1.61GiB   <toplevel>
> 0/256         16.00KiB     16.00KiB   backup
> 0/258         16.00KiB     16.00KiB   backup-btrfssend
> 0/260          1.06GiB      1.06GiB   .beeshome
> 0/261         63.74GiB     63.74GiB   backup/win_kodi_ro.20260328_21:48:59
> 0/262        229.51GiB    229.51GiB   backup/ubuntu_kodi_ro.20260328_10:19:47
> 0/263        297.04MiB    297.04MiB   <squota space holder> <- this has been there for days
> 0/264        187.38GiB    187.38GiB   backup/0Notmachines_kodi_ro.20260325_20:08:49
> 0/266         10.37GiB     10.37GiB   backup/1Appliances_kodi_ro.20260325_23:22:32
> 0/268        294.27GiB    294.27GiB   backup/debian32_kodi_ro.20260325_23:43:06
> 0/269        295.74GiB    295.74GiB   backup/debian64_kodi_ro.20260327_10:11:40
> gargamel:/mnt/btrfs_pool2/backup# btrfs subvolume delete debian64_kodi_ro.20260327_10:11:40/
> Delete subvolume 269 (no-commit): '/mnt/btrfs_pool2/backup/debian64_kodi_ro.20260327_10:11:40'
> gargamel:/mnt/btrfs_pool2/backup# btrfs qgroup show .
> Qgroupid    Referenced    Exclusive   Path
> --------    ----------    ---------   ----
> 0/5            1.61GiB      1.61GiB   <toplevel>
> 0/256         16.00KiB     16.00KiB   backup
> 0/258         16.00KiB     16.00KiB   backup-btrfssend
> 0/260          1.06GiB      1.06GiB   .beeshome
> 0/261         63.74GiB     63.74GiB   backup/win_kodi_ro.20260328_21:48:59
> 0/262        229.51GiB    229.51GiB   backup/ubuntu_kodi_ro.20260328_10:19:47
> 0/263        297.04MiB    297.04MiB   <squota space holder>
> 0/264        187.38GiB    187.38GiB   backup/0Notmachines_kodi_ro.20260325_20:08:49
> 0/266         10.37GiB     10.37GiB   backup/1Appliances_kodi_ro.20260325_23:22:32
> 0/268        294.27GiB    294.27GiB   backup/debian32_kodi_ro.20260325_23:43:06
> 0/269        295.74GiB    295.74GiB   <under deletion>
> gargamel:/mnt/btrfs_pool2/backup# btrfs qgroup show .
> Qgroupid    Referenced    Exclusive   Path
> --------    ----------    ---------   ----
> 0/5            1.63GiB      1.63GiB   <toplevel>
> 0/256         16.00KiB     16.00KiB   backup
> 0/258         16.00KiB     16.00KiB   backup-btrfssend
> 0/260          1.06GiB      1.06GiB   .beeshome
> 0/261         63.74GiB     63.74GiB   backup/win_kodi_ro.20260328_21:48:59
> 0/262        229.51GiB    229.51GiB   backup/ubuntu_kodi_ro.20260328_10:19:47
> 0/263        297.04MiB    297.04MiB   <squota space holder>
> 0/264        187.38GiB    187.38GiB   backup/0Notmachines_kodi_ro.20260325_20:08:49
> 0/266         10.37GiB     10.37GiB   backup/1Appliances_kodi_ro.20260325_23:22:32
> 0/268        294.27GiB    294.27GiB   backup/debian32_kodi_ro.20260325_23:43:06
> 0/269        287.84MiB    287.84MiB   <squota space holder>
> 0/270        321.80GiB    321.80GiB   backup/debian64_kodi_ro.20260327_10:11:40
> 
> Thanks
> Marc
> -- 
> "A mouse is a device used to point at the xterm you want to type in" - A.S.R.
>  
> Home page: http://marc.merlins.org/                       | PGP 7F55D5F27AAF9D08