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

[Hongbo Li]

On 2025/2/7 16:29, Gao Xiang wrote:
> 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@xxxxxxxxxxxxxxxxx>
> > ---
> > Changes since v1: Put the exception branch at the beginning.
> >
> > v1: 
> > https://lore.kernel.org/all/20250207064135.2249529-1-hongzhen@xxxxxxxxxxxxxxxxx/
> > ---
> >   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.

I think this version doesn't consider the fallthrough case. May be just 
use the goto statement can keep equivalent.

Thanks,
Hongbo

> Thanks,
> Gao Xiang