[PATCH 11/15] mm/swap: add helper swap_offset_available()

[Miaohe Lin]

Add helper swap_offset_available() to remove some duplicated codes.
Minor readability improvement.

Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
 mm/swapfile.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index c90298a0561a..d5d3e2d03d28 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -776,6 +776,21 @@ static void set_cluster_next(struct swap_info_struct *si, unsigned long next)
 	this_cpu_write(*si->cluster_next_cpu, next);
 }
 
+static inline bool swap_offset_available(struct swap_info_struct *si, unsigned long offset)
+{
+	if (data_race(!si->swap_map[offset])) {
+		spin_lock(&si->lock);
+		return true;
+	}
+
+	if (vm_swap_full() && READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) {
+		spin_lock(&si->lock);
+		return true;
+	}
+
+	return false;
+}
+
 static int scan_swap_map_slots(struct swap_info_struct *si,
 			       unsigned char usage, int nr,
 			       swp_entry_t slots[])
@@ -953,15 +968,8 @@ static int scan_swap_map_slots(struct swap_info_struct *si,
 scan:
 	spin_unlock(&si->lock);
 	while (++offset <= READ_ONCE(si->highest_bit)) {
-		if (data_race(!si->swap_map[offset])) {
-			spin_lock(&si->lock);
+		if (swap_offset_available(si, offset))
 			goto checks;
-		}
-		if (vm_swap_full() &&
-		    READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) {
-			spin_lock(&si->lock);
-			goto checks;
-		}
 		if (unlikely(--latency_ration < 0)) {
 			cond_resched();
 			latency_ration = LATENCY_LIMIT;
@@ -970,15 +978,8 @@ static int scan_swap_map_slots(struct swap_info_struct *si,
 	}
 	offset = si->lowest_bit;
 	while (offset < scan_base) {
-		if (data_race(!si->swap_map[offset])) {
-			spin_lock(&si->lock);
+		if (swap_offset_available(si, offset))
 			goto checks;
-		}
-		if (vm_swap_full() &&
-		    READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) {
-			spin_lock(&si->lock);
-			goto checks;
-		}
 		if (unlikely(--latency_ration < 0)) {
 			cond_resched();
 			latency_ration = LATENCY_LIMIT;
-- 
2.23.0