Re: [PATCH][BTRFS-PROGS][v4] Enhance btrfs fi df

[David Sterba <dsterba@suse.cz>]

On Thu, Feb 20, 2014 at 01:32:34PM -0500, Josef Bacik wrote:
> > Yes for 3), we may also export the information through the
> > existing ioctls if possible (eg. IOC_FS_INFO).
> > 
> 
> For _right now_ I'd say just not do the raid56 stuff if we don't
> notice any raid56 chunks from the normal load_space_info, and then if
> there are raid56 we try and run the tree search ioctl and notice if we
> get back EPERM or whatever you get when you don't have permissions.
> Then just spit out as much information that you can about the fs with
> a little note at the bottom that available calculation isn't 100% and
> you need to run as root if you want that info.

Works for me.

> Then what we could do is add another flag type for the existing
> SPACE_INFO ioctl to spit out the information you need about the
> raid5/6 chunks and then just test for those flags and make the
> adjustment necessary.  This way we avoid adding yet another ioctl and
> stuff will still work nicely for old kernels that don't have the
> updated ioctl.  Thanks,

Agreed. Extending SPACE_INFO looks suitable for this.