Re: [PATCH 1/2] mm: reorganize internal_get_user_pages_fast()

[Christoph Hellwig]

On Tue, Oct 27, 2020 at 10:33:01AM +0100, Jan Kara wrote:
> Actually there are callers that care about partial success. See e.g.
> iov_iter_get_pages() usage in fs/direct_io.c:dio_refill_pages() or
> bio_iov_iter_get_pages(). These places handle partial success just fine and
> not allowing partial success from GUP could regress things...

But most users do indeed not care.  Maybe an explicit FOLL_PARTIAL to
opt into partial handling could clean up a lot of the mess.  Maybe just
for pin_user_pages for now.