Comment 4 for bug 484786

Revision history for this message
Simon Déziel (sdeziel) wrote :

Nowadays, btrfs snapshots can only be taken by the owner of the source subvol. https://btrfs.readthedocs.io/en/latest/ch-mount-options.html#btrfs-specific-mount-options:

> Historically, any user could create a snapshot even if he was not owner of the source subvolume, the subvolume deletion has been restricted for that reason. The subvolume creation has been restricted ...

I just tested this in a Jammy VM (FYI btrfsctl was replaced by `btrfs subvolume snapshot`):

```
ubuntu@bj:~$ uname -a
Linux bj 5.15.0-75-generic #82-Ubuntu SMP Tue Jun 6 23:10:23 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
ubuntu@bj:~$ dpkg -l| grep btrfs
ii btrfs-progs 5.16.2-1 amd64 Checksumming Copy on Write Filesystem utilities

ubuntu@bj:~$ mount | grep btrfs
/dev/sda3 on /home type btrfs (rw,noatime,space_cache=v2,subvolid=5,subvol=/)

# Trying while /home is root owned
ubuntu@bj:~$ btrfs subvolume snapshot /home ./homefoo
Create a snapshot of '/home' in './homefoo'
ERROR: cannot snapshot '/home': Operation not permitted

# Changing ownership of the source subvol
ubuntu@bj:~$ sudo chown ubuntu: /home

# Trying now that /home is owned by ubuntu:
ubuntu@bj:~$ btrfs subvolume snapshot /home ./homefoo
Create a snapshot of '/home' in './homefoo'
```

So I don't think it's a concern anymore but I won't fiddle with the bug status and leave that to others ;)