Re: cannot read default subvolume id?

[Ulli Horlacher <framstag@rus.uni-stuttgart.de>]

On Mon 2025-07-28 (08:06), Qu Wenruo wrote:
> 
> 
> 圚 2025/7/28 03:16, Ulli Horlacher 写é":
> 
> >
> > Why is there a "cannot read default subvolume id"?
> >
> > tux@quak:~: btrfs sub create xx
> > Create subvolume './xx'
> >
> > tux@quak:~: btrfs sub del xx
> > WARNING: cannot read default subvolume id: Operation not permitted
> 
> It's a warning, not an error. And you can see on the next line, the
> deletion happened without any problem.

But this warning confuses a user: 
Is there a problem?
What is going wrong?
Have I made a mistake?


> You're running as a non-root user, meanwhile default subvolume id search
> is done using tree search ioctl, which require root privilege.

Why is this subvolume id search necessary for subvolume deletion and why 
is it just a warning and apparently no problem at all?
If it does not have any consequences, it should not be displayed.

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum TIK
Universitaet Stuttgart         E-Mail: horlacher@tik.uni-stuttgart.de
Allmandring 30a                Tel:    ++49-711-68565868
70569 Stuttgart (Germany)      WWW:    https://www.tik.uni-stuttgart.de/
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