Re: [PATCH 1/6] xfs: snapshot scrub stats when rendering them

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Sep 07, 2026 at 07:58:33AM +0200, Christoph Hellwig wrote:
> On Thu, Sep 03, 2026 at 11:26:02PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > LOLLM complains about concurrency problems in the scrub stats code
> > because xchk_stats_format doesn't synchronize in any way with updates.
> > These stats are only reported through debugfs so I don't think it really
> > matters, but I guess I exist to make bots happy now.
> 
> What concurrency problem?  There should be no need to have an exact
> snapshot of all counters, so it's really READ_ONCE/WRITE_ONCE that
> are needed here I think?

Yeah, I suppose I could have gone with READ_ONCE instead of the
spinlock, but I also don't think the stats file is a hot path. :)

> Either way maybe add a comment explaining the snapshotting if we want
> to stick to it?

"Snapshot the entire stats object with a spinlock because this isn't a
hot path and we don't have to worry about users seeing slightly weird
numbers (e.g. invocations has incremented but none of the outcomes have)
if we race with xchk_stats_merge_one"?

--D