mm/page_alloc.c: clean code by merging two functions

finalise_ac() is just 'epilogue' for 'prepare_alloc_pages'.  Therefore
there is no need to keep them both so 'finalise_ac' content can be merged
into prepare_alloc_pages() code.  It would make __alloc_pages_nodemask()
cleaner when it comes to readability.
Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@kernel.org>
Link: https://lkml.kernel.org/r/20200916110118.6537-1-mateusznosek0@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -4838,12 +4838,6 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
 
 	*alloc_flags = current_alloc_flags(gfp_mask, *alloc_flags);
 
-	return true;
-}
-
-/* Determine whether to spread dirty pages and what the first usable zone */
-static inline void finalise_ac(gfp_t gfp_mask, struct alloc_context *ac)
-{
 	/* Dirty zone balancing only done in the fast path */
 	ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
 
@@ -4854,6 +4848,8 @@ static inline void finalise_ac(gfp_t gfp_mask, struct alloc_context *ac)
 	 */
 	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
 					ac->highest_zoneidx, ac->nodemask);
+
+	return true;
 }
 
 /*
@@ -4882,8 +4878,6 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 	if (!prepare_alloc_pages(gfp_mask, order, preferred_nid, nodemask, &ac, &alloc_mask, &alloc_flags))
 		return NULL;
 
-	finalise_ac(gfp_mask, &ac);
-
 	/*
 	 * Forbid the first pass from falling back to types that fragment
 	 * memory until all local zones are considered.