Re: [PATCH 3/4] xfs: disable reaping in fscounters scrub

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

On Fri, Apr 28, 2023 at 12:20:41PM +1000, Dave Chinner wrote:
> On Thu, Apr 27, 2023 at 03:49:37PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > The fscounters scrub code doesn't work properly because it cannot
> > quiesce updates to the percpu counters in the filesystem, hence it
> > returns false corruption reports.  This has been fixed properly in
> > one of the online repair patchsets that are under review by replacing
> > the xchk_disable_reaping calls with an exclusive filesystem freeze.
> > Disabling background gc isn't sufficient to fix the problem.
> > 
> > In other words, scrub doesn't need to call xfs_inodegc_stop, which is
> > just as well since it wasn't correct to allow scrub to call
> > xfs_inodegc_start when something else could be calling xfs_inodegc_stop
> > (e.g. trying to freeze the filesystem).
> > 
> > Neuter the scrubber for now, and remove the xchk_*_reaping functions.
> > 
> > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> 
> Looks ok, minor nit below.
> 
> > @@ -453,6 +446,9 @@ xchk_fscounters(
> >  	if (frextents > mp->m_sb.sb_rextents)
> >  		xchk_set_corrupt(sc);
> >  
> > +	/* XXX: We can't quiesce percpu counter updates, so exit early. */
> > +	return 0;
> 
> Can you just add to this that we can re-enable this functionality
> when we have the exclusive freeze functionality in the kernel?

Will do.

--D

> With that,
> 
> Reviewed-by: Dave Chinner <dchinner@redhat.com>
> 
> -- 
> Dave Chinner
> david@fromorbit.com