Re: [PATCH 1/1] btrfs-progs: fi usage: implement raid56

["Stéphane Lesimple" <stephane_btrfs@lesimple.fr>]

Le 2019-03-17 19:41, Goffredo Baroncelli a écrit :
> On 17/03/2019 13.51, stephane_btrfs@lesimple.fr wrote:
> [...]
>> -		if (!ratio)
>> -			warning("RAID56 detected, not implemented");
>> -
> 
> IIRC one of the problem which lead to this code was that the not root
> user cannot
> access to chunkinfo. So the (regular) user should be warned about
> that: the printed info may be not correct.


I think you may be referencing this other warning:

         ret = load_chunk_info(fd, chunkinfo, chunkcount);
         if (ret == -EPERM) {
                 warning("cannot read detailed chunk info, per-device 
usage will not be shown, run as root");

This one is still present, and matches exactly what you say:
it fires when btrfs fi usage is run under a non-root user.

The "RAID56 detected, not implemented" warning, on the other hand,
is displayed even under the root user, and indicates that it's normal
that most of the counters of "filesystem usage" are at zero, because
the code to compute these properly under raid5/raid6 isn't there yet,
and it's actually precisely this missing feature that my patch tries to 
add!

Thanks,

Stéphane.