Re: [PATCH 1/5] mm: add PSI accounting around ->read_folio and ->readahead calls

[Christoph Hellwig <hch@lst.de>]

On Sat, Sep 10, 2022 at 05:34:02AM -0600, Jens Axboe wrote:
> >  	/* Start the actual read. The read will unlock the page. */
> > +	if (unlikely(workingset))
> > +		psi_memstall_enter(&pflags);
> >  	error = filler(file, folio);
> > +	if (unlikely(workingset))
> > +		psi_memstall_leave(&pflags);
> >  	if (error)
> >  		return error;
> 
> I think this would read better as:
> 
>   	/* Start the actual read. The read will unlock the page. */
> 	if (unlikely(workingset)) {
> 		psi_memstall_enter(&pflags);
> 		error = filler(file, folio);
> 		psi_memstall_leave(&pflags);
> 	} else {
> 		error = filler(file, folio);
> 	}
>   	if (error)
>   		return error;

I had it both ways.  For any non-trivial code in the conditionals I
tend to go with your version all the time.  But for two times a single
lines both variants tends to suck, so I can live with either one.