Re: [PATCH] erofs: remove unneeded icur field from struct z_erofs_decompress_frontend

[Gao Xiang]

On 2023/4/17 15:15, Yue Hu wrote:
> On Mon, 17 Apr 2023 15:00:25 +0800
> Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> wrote:

..

> > Although please help refine the comment below:
> >
> > 	/* scan & fill inplace I/O pages in the reverse order */
>
> Ok, will refine it in v2.

I rethink this, I don't want to go far in this way, and this makes a
O(n) scan into O(n^2) when a single inplace I/O page is added.

So sorry, I don't think it's a good way, although I also don't think
`icur` is a good name and we might need to find a better name.

Thanks,
Gao Xiang

> > Thanks,
> > Gao Xiang
> >
> > > > +    unsigned int icur = pcl->pclusterpages;
> > > > -    while (fe->icur > 0) {
> > > > -        if (!cmpxchg(&pcl->compressed_bvecs[--fe->icur].page,
> > > > +    while (icur > 0) {
> > > > +        if (!cmpxchg(&pcl->compressed_bvecs[--icur].page,
> > > >                     NULL, bvec->page)) {
> > > > -            pcl->compressed_bvecs[fe->icur] = *bvec;
> > > > +            pcl->compressed_bvecs[icur] = *bvec;
> > > >                return true;
> > > >            }
> > > >        }
> > > > @@ -877,8 +876,6 @@ static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe)
> > > >        }
> > > >        z_erofs_bvec_iter_begin(&fe->biter, &fe->pcl->bvset,
> > > >                    Z_EROFS_INLINE_BVECS, fe->pcl->vcnt);
> > > > -    /* since file-backed online pages are traversed in reverse order */
> > > > -    fe->icur = z_erofs_pclusterpages(fe->pcl);
> > > >        return 0;
> > > >    }