Re: [PATCH 2/2] block: no-copy bvec for direct IO

[Christoph Hellwig]

On Wed, Dec 09, 2020 at 12:01:27PM +0000, Pavel Begunkov wrote:
> On 09/12/2020 08:40, Christoph Hellwig wrote:
> >> +	/*
> >> +	 * In practice groups of pages tend to be accessed/reclaimed/refaulted
> >> +	 * together. To not go over bvec for those who didn't set BIO_WORKINGSET
> >> +	 * approximate it by looking at the first page and inducing it to the
> >> +	 * whole bio
> >> +	 */
> >> +	if (unlikely(PageWorkingset(iter->bvec->bv_page)))
> >> +		bio_set_flag(bio, BIO_WORKINGSET);
> > 
> > IIRC the feedback was that we do not need to deal with BIO_WORKINGSET
> > at all for direct I/O.
> 
> I was waiting for the conversation to unfold, i.e. for Johannes to
> answer. BTW, would the same (skipping BIO_WORKINGSET) stand true for
> iomap?

iomap direct I/O: yes.