[PATCH] mm: Simplify shrink_inactive_list()

[Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>]

This merges together duplicating patterns of code.
Changes in enum vm_event_item is made to underline
that *_DIRECT and *_KSWAPD must differ by 1.

Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
---
 include/linux/vm_event_item.h |    4 ++--
 mm/vmscan.c                   |   31 +++++++++----------------------
 2 files changed, 11 insertions(+), 24 deletions(-)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 47a3441cf4c4..8f1403e692a2 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -31,9 +31,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		PGLAZYFREED,
 		PGREFILL,
 		PGSTEAL_KSWAPD,
-		PGSTEAL_DIRECT,
+		PGSTEAL_DIRECT = PGSTEAL_KSWAPD + 1,
 		PGSCAN_KSWAPD,
-		PGSCAN_DIRECT,
+		PGSCAN_DIRECT = PGSCAN_KSWAPD + 1,
 		PGSCAN_DIRECT_THROTTLE,
 #ifdef CONFIG_NUMA
 		PGSCAN_ZONE_RECLAIM_FAILED,
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 836b28913bd7..f8ac0825d1c7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1907,6 +1907,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	unsigned long nr_taken;
 	struct reclaim_stat stat;
 	int file = is_file_lru(lru);
+	int is_direct = !current_is_kswapd();
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
 	bool stalled = false;
@@ -1934,17 +1935,10 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken);
 	reclaim_stat->recent_scanned[file] += nr_taken;
 
-	if (current_is_kswapd()) {
-		if (global_reclaim(sc))
-			__count_vm_events(PGSCAN_KSWAPD, nr_scanned);
-		count_memcg_events(lruvec_memcg(lruvec), PGSCAN_KSWAPD,
-				   nr_scanned);
-	} else {
-		if (global_reclaim(sc))
-			__count_vm_events(PGSCAN_DIRECT, nr_scanned);
-		count_memcg_events(lruvec_memcg(lruvec), PGSCAN_DIRECT,
-				   nr_scanned);
-	}
+	if (global_reclaim(sc))
+		__count_vm_events(PGSCAN_KSWAPD + is_direct, nr_scanned);
+	__count_memcg_events(lruvec_memcg(lruvec), PGSCAN_KSWAPD + is_direct,
+			     nr_scanned);
 	spin_unlock_irq(&pgdat->lru_lock);
 
 	if (nr_taken == 0)
@@ -1955,17 +1949,10 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 
 	spin_lock_irq(&pgdat->lru_lock);
 
-	if (current_is_kswapd()) {
-		if (global_reclaim(sc))
-			__count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed);
-		count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_KSWAPD,
-				   nr_reclaimed);
-	} else {
-		if (global_reclaim(sc))
-			__count_vm_events(PGSTEAL_DIRECT, nr_reclaimed);
-		count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_DIRECT,
-				   nr_reclaimed);
-	}
+	if (global_reclaim(sc))
+		__count_vm_events(PGSTEAL_KSWAPD + is_direct, nr_reclaimed);
+	__count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_KSWAPD + is_direct,
+			     nr_reclaimed);
 	reclaim_stat->recent_rotated[0] = stat.nr_activate[0];
 	reclaim_stat->recent_rotated[1] = stat.nr_activate[1];