mm: compaction: make compact_zone_order() static

There's no compact_zone_order() user outside file scope, so make it static.
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/compaction.h

@@ -24,8 +24,6 @@ extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
 			int order, gfp_t gfp_mask, nodemask_t *mask,
 			bool sync);
 extern unsigned long compaction_suitable(struct zone *zone, int order);
-extern unsigned long compact_zone_order(struct zone *zone, int order,
-					gfp_t gfp_mask, bool sync);
 
 /* Do not skip compaction more than 64 times */
 #define COMPACT_MAX_DEFER_SHIFT 6
@@ -69,12 +67,6 @@ static inline unsigned long compaction_suitable(struct zone *zone, int order)
 	return COMPACT_SKIPPED;
 }
 
-static inline unsigned long compact_zone_order(struct zone *zone, int order,
-					       gfp_t gfp_mask, bool sync)
-{
-	return COMPACT_CONTINUE;
-}
-
 static inline void defer_compaction(struct zone *zone)
 {
 }

mm/compaction.c

@@ -582,7 +582,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 	return ret;
 }
 
-unsigned long compact_zone_order(struct zone *zone,
+static unsigned long compact_zone_order(struct zone *zone,
 				 int order, gfp_t gfp_mask,
 				 bool sync)
 {