[PATCH v2] mm/vmscan: define macros for refaults in struct lruvec

[cgel . zte]

From: Yang Yang <yang.yang29@xxxxxxxxxx>

The magic number 0 and 1 are used in several places in vmscan.c.
Define macros for them to improve code readability.

Signed-off-by: Yang Yang <yang.yang29@xxxxxxxxxx>
---
Change for v2:
 - fix compile error when CONFIG_NFSD is y
---
 include/linux/mmzone.h | 2 ++
 mm/vmscan.c            | 8 ++++----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index e24b40c52468..8f571dc7c524 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -306,6 +306,8 @@ static inline bool is_active_lru(enum lru_list lru)
 	return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
 }
 
+#define WORKINGSET_ANON 0
+#define WORKINGSET_FILE 1
 #define ANON_AND_FILE 2
 
 enum lruvec_flags {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b2b1431352dc..428f8fa60331 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3230,7 +3230,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 
 		refaults = lruvec_page_state(target_lruvec,
 				WORKINGSET_ACTIVATE_ANON);
-		if (refaults != target_lruvec->refaults[0] ||
+		if (refaults != target_lruvec->refaults[WORKINGSET_ANON] ||
 			inactive_is_low(target_lruvec, LRU_INACTIVE_ANON))
 			sc->may_deactivate |= DEACTIVATE_ANON;
 		else
@@ -3243,7 +3243,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 		 */
 		refaults = lruvec_page_state(target_lruvec,
 				WORKINGSET_ACTIVATE_FILE);
-		if (refaults != target_lruvec->refaults[1] ||
+		if (refaults != target_lruvec->refaults[WORKINGSET_FILE] ||
 		    inactive_is_low(target_lruvec, LRU_INACTIVE_FILE))
 			sc->may_deactivate |= DEACTIVATE_FILE;
 		else
@@ -3559,9 +3559,9 @@ static void snapshot_refaults(struct mem_cgroup *target_memcg, pg_data_t *pgdat)
 
 	target_lruvec = mem_cgroup_lruvec(target_memcg, pgdat);
 	refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_ANON);
-	target_lruvec->refaults[0] = refaults;
+	target_lruvec->refaults[WORKINGSET_ANON] = refaults;
 	refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_FILE);
-	target_lruvec->refaults[1] = refaults;
+	target_lruvec->refaults[WORKINGSET_FILE] = refaults;
 }
 
 /*
-- 
2.25.1