Are you saying that it would work either way?
On Mon, 7 Dec 2020 at 11:12, Ming Lei <ming.lei@xxxxxxxxxx> wrote:
>
> On Sun, Dec 06, 2020 at 01:18:02PM +0800, Tom Yan wrote:
> > While it seems to have worked for so long, it doesn't seem right
> > that we set the new bio as the parent. bio_chain() seems to be used
> > in the other way everywhere else anyway.
> >
> > Signed-off-by: Tom Yan <tom.ty89@xxxxxxxxx>
> > ---
> > block/blk-lib.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/block/blk-lib.c b/block/blk-lib.c
> > index e90614fd8d6a..918deaf5c8a4 100644
> > --- a/block/blk-lib.c
> > +++ b/block/blk-lib.c
> > @@ -15,7 +15,7 @@ struct bio *blk_next_bio(struct bio *bio, unsigned int nr_pages, gfp_t gfp)
> > struct bio *new = bio_alloc(gfp, nr_pages);
> >
> > if (bio) {
> > - bio_chain(bio, new);
> > + bio_chain(new, bio);
> > submit_bio(bio);
> > }
>
> This patch isn't needed. We simply wait for completion of the last issued bio, which
> .bi_end_io(submit_bio_wait_endio) is only called after all previous bios are done.
>
> And the last bio is the ancestor of the whole chained bios, which are
> submitted in the following way(order):
>
> bio 0 ---> bio 1 ---> ... -> bio N(the last bio)
>
>
> thanks,
> Ming
>
