Re: [PATCH v2] erofs: use Z_EROFS_LCLUSTER_TYPE_MAX to simplify switches

[Gao Xiang <hsiangkao@linux.alibaba.com>]

On 2025/2/7 16:08, Hongzhen Luo wrote:
> There's no need to enumerate each type.  No logic changes.
> 
> Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
> ---
> Changes since v1: Put the exception branch at the beginning.
> 
> v1: https://lore.kernel.org/all/20250207064135.2249529-1-hongzhen@linux.alibaba.com/
> ---
>   fs/erofs/zmap.c | 65 +++++++++++++++++++++----------------------------
>   1 file changed, 28 insertions(+), 37 deletions(-)
> 
> diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
> index 689437e99a5a..f65c76991e02 100644
> --- a/fs/erofs/zmap.c
> +++ b/fs/erofs/zmap.c
> @@ -265,23 +265,22 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
>   		if (err)
>   			return err;
>   
> -		switch (m->type) {
> -		case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
> +		if (m->type >= Z_EROFS_LCLUSTER_TYPE_MAX) {
> +			erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
> +				  m->type, lcn, vi->nid);
> +			DBG_BUGON(1);
> +			return -EOPNOTSUPP;
> +		}
> +
> +		if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
>   			lookback_distance = m->delta[0];
>   			if (!lookback_distance)
>   				goto err_bogus;
>   			continue;
> -		case Z_EROFS_LCLUSTER_TYPE_PLAIN:
> -		case Z_EROFS_LCLUSTER_TYPE_HEAD1:
> -		case Z_EROFS_LCLUSTER_TYPE_HEAD2:
> +		} else if (m->type < Z_EROFS_LCLUSTER_TYPE_MAX) {


Just `} else {` here?

>   			m->headtype = m->type;
>   			m->map->m_la = (lcn << lclusterbits) | m->clusterofs;
>   			return 0;
> -		default:
> -			erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
> -				  m->type, lcn, vi->nid);
> -			DBG_BUGON(1);
> -			return -EOPNOTSUPP;
>   		}
>   	}
>   err_bogus:
> @@ -329,35 +328,31 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
>   	DBG_BUGON(lcn == initial_lcn &&
>   		  m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD);
>   
> -	switch (m->type) {
> -	case Z_EROFS_LCLUSTER_TYPE_PLAIN:
> -	case Z_EROFS_LCLUSTER_TYPE_HEAD1:
> -	case Z_EROFS_LCLUSTER_TYPE_HEAD2:
> +	if (m->type >= Z_EROFS_LCLUSTER_TYPE_MAX) {
> +		erofs_err(sb, "cannot found CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);
> +		DBG_BUGON(1);
> +		return -EFSCORRUPTED;
> +	}

No, I don't think it's equivalent, please use
the previous version for this part instead.

Thanks,
Gao Xiang