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

[Carlos Maiolino <cem@kernel.org>]

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.
> 
> Cc: <stable@vger.kernel.org> # v6.6
> Fixes: d7a74cad8f4513 ("xfs: track usage statistics of online fsck")
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> Assisted-by: LOLLM # finding obvious bugs
> ---
>  fs/xfs/scrub/stats.c |   32 +++++++++++++++++++-------------
>  1 file changed, 19 insertions(+), 13 deletions(-)
> 

Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>

> 
> diff --git a/fs/xfs/scrub/stats.c b/fs/xfs/scrub/stats.c
> index 76f2515188d1b1..f3f1fbfb6d9955 100644
> --- a/fs/xfs/scrub/stats.c
> +++ b/fs/xfs/scrub/stats.c
> @@ -99,25 +99,31 @@ xchk_stats_format(
>  	int			ret = 0;
>  
>  	for (i = 0; i < XFS_SCRUB_TYPE_NR; i++, css++) {
> +		struct xchk_scrub_stats	fss;
> +
>  		if (!name_map[i])
>  			continue;
>  
> +		spin_lock(&css->css_lock);
> +		memcpy(&fss, css, offsetof(struct xchk_scrub_stats, css_lock));
> +		spin_unlock(&css->css_lock);
> +
>  		ret = scnprintf(buf, remaining,
>   "%s %u %u %u %u %u %u %u %u %u %llu %u %u %llu\n",
>  				name_map[i],
> -				(unsigned int)css->invocations,
> -				(unsigned int)css->clean,
> -				(unsigned int)css->corrupt,
> -				(unsigned int)css->preen,
> -				(unsigned int)css->xfail,
> -				(unsigned int)css->xcorrupt,
> -				(unsigned int)css->incomplete,
> -				(unsigned int)css->warning,
> -				(unsigned int)css->retries,
> -				(unsigned long long)css->checktime_us,
> -				(unsigned int)css->repair_invocations,
> -				(unsigned int)css->repair_success,
> -				(unsigned long long)css->repairtime_us);
> +				(unsigned int)fss.invocations,
> +				(unsigned int)fss.clean,
> +				(unsigned int)fss.corrupt,
> +				(unsigned int)fss.preen,
> +				(unsigned int)fss.xfail,
> +				(unsigned int)fss.xcorrupt,
> +				(unsigned int)fss.incomplete,
> +				(unsigned int)fss.warning,
> +				(unsigned int)fss.retries,
> +				(unsigned long long)fss.checktime_us,
> +				(unsigned int)fss.repair_invocations,
> +				(unsigned int)fss.repair_success,
> +				(unsigned long long)fss.repairtime_us);
>  		if (ret <= 0)
>  			break;
>  
> 
>