Re: [PATCH v5 4/9] iov_iter: Add a function to extract a page list from an iterator

[Al Viro]

On Wed, Jan 11, 2023 at 02:28:05PM +0000, David Howells wrote:

> +ssize_t iov_iter_extract_pages(struct iov_iter *i,
> +			       struct page ***pages,
> +			       size_t maxsize,
> +			       unsigned int maxpages,
> +			       unsigned int gup_flags,
> +			       size_t *offset0,
> +			       unsigned int *cleanup_mode)

This cleanup_mode thing is wrong.  It's literally a trivial
function of ->user_backed and ->data_source - we don't
even need to look at the ->type.

Separate it into an inline helper and be done with that;
don't carry it all over the place.

It's really "if not user-backed => 0, otherwise it's FOLL_PIN or FOLL_GET,
depending upon the direction".