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Tasklist

FS#52820 - [devtools] makechrootpkg don't delete btrfs child subvolumes

Attached to Project: Arch Linux
Opened by Robin D (Koaxiel) - Thursday, 02 February 2017, 07:43 GMT
Last edited by Doug Newgard (Scimmia) - Friday, 24 March 2017, 16:11 GMT
Task Type Bug Report
Category Packages: Extra
Status Closed
Assigned To Pierre Schmitz (Pierre)
Architecture All
Severity Medium
Priority Normal
Reported Version 5.0.1
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 1
Private No

Details

Summary and Info:
systemd-nspawn follows instructions in /usr/lib/tmpfiles.d/systemd-nspawn.conf, i.e if you use btrfs, a subvolume is created for /var/lib/machines even in a container.
makechrootpkg fails in this case to clean the "copydir" because btrfs refuses to delete "copydir" as long as child subvolumes exist.

I attached a patch for makechrootpkg.in to try to fix this case.
   patch.txt (1.3 KiB)
This task depends upon

Closed by  Doug Newgard (Scimmia)
Friday, 24 March 2017, 16:11 GMT
Reason for closing:  Fixed
Additional comments about closing:  https://git.archlinux.org/devtools.git/c ommit/?id=eec7fcf965763d5395c336f92cd56b 193d054947
Comment by Dave Reisner (falconindy) - Thursday, 02 February 2017, 13:12 GMT
Relevant: https://lists.archlinux.org/pipermail/arch-projects/2017-January/004464.html

More relevant: Your patch doesn't reliably work. For example, on my machine, I'd end up with:

# btrfs subvolume list --sort=-rootid -o /build/extra-x86_64/noclaf/
ID 1441 gen 18140 top level 1440 path chroots/extra-x86_64/noclaf/var/lib/machines

But /chroots/extra-x86_64/noclaf/var/lib/machines isn't a real path -- it *should* be /mnt/Haven/chroots/extra-x86_64/noclaf/var/lib/machines (/build is a symlink to /mnt/Haven/chroots).

Aside, your patch has some syntactical/safety issues. You're expanding the output of btrfs directly into an array, which results in an array of words, not lines ('ID', '1441', 'gen', etc) rather than ('ID 1441 gen ...')
Comment by Robin D (Koaxiel) - Friday, 03 February 2017, 20:04 GMT
Thank you for your help.
I read the thread on the mailing list and I wonder if symlink "copydir" to /var/lib/machines wouldn't be more preferable.
Thus we could use machinectl remove "copydir" to delete the subvolume and the child subvolumes. It wouldn't be necessary to use btrfs tools.
At the moment, I can't manage to remove the subvolume via machinectl because an issue with systemd : https://github.com/systemd/systemd/issues/2001

What do you think of this method?

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