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 <[e-mail]>
Acked-by: David Rientjes <[e-mail]>
Reviewed-by: Minchan Kim <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/compaction.h

···
 			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
···
 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

···
 	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)
 {