Re: [RFC PATCH 0/7] mm: Make more use of readahead_control

David Howells
2020-09-01T19:44:21Z

Matthew Wilcox <willy@infradead.org> wrote:

> > Note that I've been
> > passing the number of pages to read in rac->_nr_pages, and then saving it
> > and changing it certain points, e.g. page_cache_readahead_unbounded().
>
> I do not like this. You're essentially mutating the meaning of _nr_pages
> as the ractl moves down the stack, and that's going to lead to bugs.
> I'd keep it as a separate argument.

The meaning isn't specified in linux/pagemap.h. Can you adjust the comments
on the struct and on readahead_count() to make it more clear what the value
represents?

Thanks,
David