On Wed, 24 Aug 2022 16:45:59 +0800
Gao Xiang <[email protected]> wrote:

> Hi Yue,
> 
> On Sun, Aug 21, 2022 at 09:57:24PM +0800, [email protected] wrote:
> > From: Yue Hu <[email protected]>
> > 
> > Add support to uncompressed data layout with on-disk offset for
> > compressed files.  
> 
> Sorry for some delay.
> 
> Add interlaced uncompressed data layout for compressed files.
> 
> > 
> > Signed-off-by: Yue Hu <[email protected]>
> > ---
> >  include/erofs/decompress.h |  3 +++
> >  lib/data.c                 |  8 +++++++-
> >  lib/decompress.c           | 10 ++++++++--
> >  3 files changed, 18 insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/erofs/decompress.h b/include/erofs/decompress.h
> > index 82bf7b8..b622df5 100644
> > --- a/include/erofs/decompress.h
> > +++ b/include/erofs/decompress.h
> > @@ -23,6 +23,9 @@ struct z_erofs_decompress_req {
> >     unsigned int decodedskip;
> >     unsigned int inputsize, decodedlength;
> >  
> > +   /* head offset of uncompressed data */
> > +   unsigned int shiftedhead;  
> 
>       /* cut point of interlaced uncompressed data */
>       unsigned int interlaced_offset;
> 
> > +
> >     /* indicate the algorithm will be used for decompression */
> >     unsigned int alg;
> >     bool partial_decoding;
> > diff --git a/lib/data.c b/lib/data.c
> > index 2af73c7..008790d 100644
> > --- a/lib/data.c
> > +++ b/lib/data.c
> > @@ -226,7 +226,7 @@ static int z_erofs_read_data(struct erofs_inode *inode, 
> > char *buffer,
> >     };
> >     struct erofs_map_dev mdev;
> >     bool partial;
> > -   unsigned int bufsize = 0;
> > +   unsigned int bufsize = 0, head;
> >     char *raw = NULL;
> >     int ret = 0;
> >  
> > @@ -307,10 +307,16 @@ static int z_erofs_read_data(struct erofs_inode 
> > *inode, char *buffer,
> >             if (ret < 0)
> >                     break;
> >  
> > +           head = 0;
> > +           if (erofs_sb_has_fragments() &&  
> 
> Can we add another Z_EROFS_ADVISE_ for this, such as
> Z_EROFS_ADVISE_INTERLACED_UNCOMPRESSED_DATA ?

Sounds good, let's do this.

Thanks.

> 
> > +               map.m_algorithmformat == Z_EROFS_COMPRESSION_SHIFTED)
> > +                   head = erofs_blkoff(end);
> > +
> >             ret = z_erofs_decompress(&(struct z_erofs_decompress_req) {
> >                                     .in = raw,
> >                                     .out = buffer + end - offset,
> >                                     .decodedskip = skip,
> > +                                   .shiftedhead = head,
> >                                     .inputsize = map.m_plen,
> >                                     .decodedlength = length,
> >                                     .alg = map.m_algorithmformat,
> > diff --git a/lib/decompress.c b/lib/decompress.c
> > index 1661f91..08a0861 100644
> > --- a/lib/decompress.c
> > +++ b/lib/decompress.c
> > @@ -132,14 +132,20 @@ out:
> >  int z_erofs_decompress(struct z_erofs_decompress_req *rq)
> >  {
> >     if (rq->alg == Z_EROFS_COMPRESSION_SHIFTED) {
> > +           unsigned int count, rightpart;
> > +
> >             if (rq->inputsize > EROFS_BLKSIZ)
> >                     return -EFSCORRUPTED;
> >  
> >             DBG_BUGON(rq->decodedlength > EROFS_BLKSIZ);
> >             DBG_BUGON(rq->decodedlength < rq->decodedskip);
> >  
> > -           memcpy(rq->out, rq->in + rq->decodedskip,
> > -                  rq->decodedlength - rq->decodedskip);
> > +           count = rq->decodedlength - rq->decodedskip;
> > +           rightpart = min(EROFS_BLKSIZ - rq->shiftedhead, count);
> > +
> > +           memcpy(rq->out, rq->in + (erofs_sb_has_fragments() ?  
> 
> same here.
> 
> Thanks,
> Gao Xiang
> 
> > +                  rq->shiftedhead : rq->decodedskip), rightpart);
> > +           memcpy(rq->out + rightpart, rq->in, count - rightpart);
> >             return 0;
> >     }
> >  
> > -- 
> > 2.17.1  

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