Re: [PATCH] vmstat: don't auto expand the sysfs files

[Matthew Wilcox]

On Mon, Dec 11, 2023 at 03:46:44PM +0000, Pasha Tatashin wrote:
> +++ b/drivers/base/node.c
> @@ -520,26 +520,34 @@ static ssize_t node_read_vmstat(struct device *dev,
>  	int i;
>  	int len = 0;
>  
> -	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
> -		len += sysfs_emit_at(buf, len, "%s %lu\n",
> -				     zone_stat_name(i),
> -				     sum_zone_node_page_state(nid, i));
> +	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
> +		if (vmstat_text[ZONE_STAT_NAME_IDX(i)].flags & VMSTAT_SHOW_SYSFS) {
> +			len += sysfs_emit_at(buf, len, "%s %lu\n",
> +					     zone_stat_name(i),
> +					     sum_zone_node_page_state(nid, i));
> +		}
> +	}

This seems overly complicated.  Why not do:

	for (i = 0; i < NR_VM_ZONE_STAT_SYSFS_ITEMS; i++)

and have assertions that this number doesn't change (and require people
to add to the list after that point)?