Re: [PATCH v1 2/6] fs: use on-stack-bio if backing device has BDI_CAP_SYNC capability

[Minchan Kim]

On Tue, Aug 08, 2017 at 06:29:04AM -0700, Matthew Wilcox wrote:
> On Tue, Aug 08, 2017 at 05:49:59AM -0700, Matthew Wilcox wrote:
> > +	struct bio sbio;
> > +	struct bio_vec sbvec;
> 
> ... this needs to be sbvec[nr_pages], of course.
> 
> > -		bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
> > +		if (bdi_cap_synchronous_io(inode_to_bdi(inode))) {
> > +			bio = &sbio;
> > +			bio_init(bio, &sbvec, nr_pages);
> 
> ... and this needs to be 'sbvec', not '&sbvec'.

I don't get it why we need sbvec[nr_pages].
On-stack-bio works with per-page.
May I miss something?