Re: [PATCH] block: fix disordered IO in the case recursive split

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

Hi,

在 2025/08/21 16:43, Christoph Hellwig 写道:
> On Thu, Aug 21, 2025 at 03:47:06PM +0800, Yu Kuai wrote:
> > +	if (current->bio_list) {
> > +		if (bio_flagged(bio, BIO_CHAIN))
> > +			bio_list_add_head(&current->bio_list[0], bio);
> > +		else
> > +			bio_list_add(&current->bio_list[0], bio);
> > +	} else if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) {
>
> This breaks all the code the already chains the right way around,
> and there's quite a bit of that (speaking as someone who created a few
> instances).
>
> So instead fix your submitter to chain the right way instead.

Can you give some examples as how to chain the right way? BTW, for all
the io split case, should this order be fixed? I feel we should, this
disorder can happen on any stack case, where top max_sector is greater
than stacked disk.

Thanks,
Kuai

> .