Re: [PATCH v2] erofs: fix file-backed mounts over FUSE

[Gao Xiang]

On 2024/11/15 00:18, Al Viro wrote:
> On Thu, Nov 14, 2024 at 05:01:09PM +0800, Gao Xiang wrote:
> > --- a/fs/erofs/data.c
> > +++ b/fs/erofs/data.c
> > @@ -38,7 +38,9 @@ void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset,
> >   	}
> >   	if (!folio || !folio_contains(folio, index)) {
> >   		erofs_put_metabuf(buf);
> > -		folio = read_mapping_folio(buf->mapping, index, NULL);
> > +		folio = buf->file ? read_mapping_folio(buf->file->f_mapping,
> > +					index, buf->file) :
> > +			read_mapping_folio(buf->mapping, index, NULL);
> >   		if (IS_ERR(folio))
> >   			return folio;
> >   	}
> > @@ -61,8 +63,8 @@ void erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb)
> >   {
> >   	struct erofs_sb_info *sbi = EROFS_SB(sb);
> >   
> > -	if (erofs_is_fileio_mode(sbi))
> > -		buf->mapping = file_inode(sbi->fdev)->i_mapping;
> > +	if (erofs_is_fileio_mode(sbi))	/* some fs like FUSE needs it */
> > +		buf->file = sbi->fdev;
>
> Would be easier to set *both* ->mapping and ->file at that point, so that
> erofs_bread() would just have read_mapping_folio(buf->mapping, index, buf->file),
> unconditionally...

Ok, will do the next version.

Thanks,
Gao Xiang