Re: [PATCH] erofs-utils: introduce fsck.erofs

[Gao Xiang <xiang@kernel.org>]

On Thu, Oct 28, 2021 at 10:10:03AM -0700, Daeho Jeong wrote:
> > > In fact, I wanted to decompress the whole data here. We can't check
> > > the data integrity,
> > > so I just wanted to check the layout of the file and that is the
> > > reason why I used z_erofs_map_blocks_iter() directly.
> >
> > Yeah, z_erofs_map_blocks_iter() here is good, yet I think we could
> > add a follow-up z_erofs_decompress() as well, at least it can verify
> > obvious compressed data corruption.
> 
> Could you enlighten me what is wrong with the below flow?
> z_erofs_decompress fails with -EIO or -EUCLEAN.
> 
>         raw = malloc(pchunk_len);
>         BUG_ON(!raw);
>         buffer = malloc(inode->i_size);
>         BUG_ON(!buffer);
> 
>         ret = dev_read(raw, 0, pchunk_len);
>         if (ret < 0) {
>                 erofs_err("an error occurred when reading compressed data "
>                           "of nid(%llu): errno(%d)", inode->nid | 0ULL, ret);
>                 goto out;
>         }
> 
>         ret = z_erofs_decompress(&(struct z_erofs_decompress_req) {
>                                 .in = raw,
>                                 .out = buffer,
>                                 .decodedskip = 0,
>                                 .inputsize = pchunk_len,
>                                 .decodedlength = inode->i_size,

I guess try to pass map.m_llen here? since we need to decode pcluster
one-by-one....

Thanks,
Gao Xiang

>                                 .alg = algorithmformat,
>                                 .partial_decoding = 0
>                                  });