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

From: Miaohe Lin
Date: Mon May 09 2022 - 09:15:13 EST


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