[RESEND 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast

[Ira Weiny]

On Mon, Mar 25, 2019 at 03:36:28PM -0700, Dan Williams wrote:
> On Mon, Mar 25, 2019 at 3:22 PM Ira Weiny <ira.weiny at intel.com> wrote:
> [..]
> > FWIW this thread is making me think my original patch which simply implemented
> > get_user_pages_fast_longterm() would be more clear.  There is some evidence
> > that the GUP API was trending that way (see get_user_pages_remote).  That seems
> > wrong but I don't know how to ensure users don't specify the wrong flag.
> 
> What about just making the existing get_user_pages_longterm() have a
> fast path option?

That would work but was not the direction we agreed upon before.[1]

At this point I would rather see this patch set applied, focus on fixing the
filesystem issues, and once that is done determine if FOLL_LONGTERM is needed
in any GUP calls.

Ira

[1] https://lkml.org/lkml/2019/2/11/2038