Re: [PATCH 1/2] btrfs: sysfs convert scnprintf and snprintf to use sysfs_emit

[David Sterba <dsterba@suse.cz>]

On Tue, Oct 19, 2021 at 08:22:09AM +0800, Anand Jain wrote:
> @@ -1264,8 +1262,7 @@ char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags)
>  			continue;
>  
>  		name = btrfs_feature_attrs[set][i].kobj_attr.attr.name;
> -		len += scnprintf(str + len, bufsize - len, "%s%s",
> -				len ? "," : "", name);
> +		len += sysfs_emit_at(str, len, "%s%s", len ? "," : "", name);

This is a different pattern the 'bufsize' is 4096 which matches
PAGE_SIZE but it's not the same thing as the show/set callbacks.

>  	}
>  
>  	return str;
> @@ -1304,8 +1301,8 @@ static void init_feature_attrs(void)
>  			if (fa->kobj_attr.attr.name)
>  				continue;
>  
> -			snprintf(name, BTRFS_FEATURE_NAME_MAX, "%s:%u",
> -				 btrfs_feature_set_names[set], i);
> +			sysfs_emit(name, "%s:%u", btrfs_feature_set_names[set],
> +				   i);

And this one too, what's worse is that BTRFS_FEATURE_NAME_MAX is 13 but
sysfs_emit assumes PAGE_SIZE.

The rest is OK, so I'd drop the two changes.