Re: [PATCH 1/2] xfs: expose the number of free zones in sysfs

[Niklas Cassel <cassel@kernel.org>]

On Wed, Apr 22, 2026 at 08:03:22AM +0200, Christoph Hellwig wrote:
> On Mon, Apr 20, 2026 at 03:50:13PM +0200, Niklas Cassel wrote:
> > The number of free zones is currently available in /proc/<pid>/mountstats
> > (which contains stats for all mounted zoned XFS filesystems), under
> > "free zones:".
> > 
> > Add a sysfs attribute /sys/fs/xfs/<dev>/zoned/nr_free_zones for the same.
> > This makes it trivial for monitoring software to read the value, for a
> > specific filesystem, without any complex parsing.
> 
> The usual way to expose stats in xfs is through the stats sysfs file.
> Which requires some parsing, but the usual monitoring tools already
> have this.

So we have the following options:
1) /sys/fs/xfs/<dev>/zoned/
2) /sys/fs/xfs/<dev>/stats/stats
3) /sys/kernel/debug/xfs/<dev>/


You say that the usual way to expose stats is through 2)
but e.g. nr_open_zones is exposed via 1), introduced in commit
62c89988dc19 ("xfs: expose the number of open zones in sysfs")
(You are the author of that commit btw :))


In my mind, nr_open_zones and nr_free_zones is very similar,
so I though it was most logical to have them in the same place.


That said, if you prefer 2) or 3) over 1) for exposing nr_free_zones,
please tell me which you prefer, and I can send a V2 with that.


Kind regards,
Niklas