mm/gup: change GUP fast to use flags rather than a write 'bool'

To facilitate additional options to get_user_pages_fast() change the
singular write parameter to be gup_flags.

This patch does not change any functionality.  New functionality will
follow in subsequent patches.

Some of the get_user_pages_fast() call sites were unchanged because they
already passed FOLL_WRITE or 0 for the write parameter.

NOTE: It was suggested to change the ordering of the get_user_pages_fast()
arguments to ensure that callers were converted.  This breaks the current
GUP call site convention of having the returned pages be the final
parameter.  So the suggestion was rejected.

Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ira Weiny <[email protected]>
Reviewed-by: Mike Marshall <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Rich Felker <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

drivers/sbus/char/oradax.c

@@ -437,7 +437,7 @@ static int dax_lock_page(void *va, struct page **p)
 
 	dax_dbg("uva %p", va);
 
-	ret = get_user_pages_fast((unsigned long)va, 1, 1, p);
+	ret = get_user_pages_fast((unsigned long)va, 1, FOLL_WRITE, p);
 	if (ret == 1) {
 		dax_dbg("locked page %p, for VA %p", *p, va);
 		return 0;