Re: lsattr loading modules, changing permissions of device nodes

[Michael Biebl]

Hi Marc

Am 16.03.21 um 19:50 schrieb Marc Haber:

Now friendly and innocent questions towards the udev maintainers:
* Do you see similiar behavior on your systems?

No

* If yes, is this intended behavior?

No

* Why does, for example, the /dev/btrfs-control device node get created
   with one set of owner/mode and then gets converted to a different one
   when someone accesses it? btrfs-progs are not installed, btrfs is not
   in use.

# grep btrfs-control /lib/udev/rules.d/*


You can manually trigger a uevent by e.g.
echo change > /sys/class/misc/btrfs-control/uevent

Has systemd-udev-trigger.service been run successfully during boot?

I don't remember any udev related changes which could cause this.

From which version to which version did you upgrade?

What you see are the default permissions of the devices. Once the device is marked as ready by the kernel and a uevent is emitted, udev will run its rules and apply the permissions. In this case /lib/udev/rules.d/50-udev-default.rules:KERNEL=="btrfs-control", GROUP="disk"

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