[RFC PATCH v3 4/4] zram: batch clear flags in slot_free with single write

[Wenchao Hao]

Replace four separate flag clear operations in slot_free() with a
single mask write. This reduces redundant read-modify-write cycles
on the same flags word.

Signed-off-by: Wenchao Hao <haowenchao@xxxxxxxxxx>
---
 drivers/block/zram/zram_drv.c | 5 +----
 drivers/block/zram/zram_drv.h | 6 ++++++
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 0d07f0901e55..b1a565d35567 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -2011,10 +2011,7 @@ static void slot_free(struct zram *zram, u32 index)
 	zram->table[index].attr.ac_time = 0;
 #endif
 
-	clear_slot_flag(zram, index, ZRAM_IDLE);
-	clear_slot_flag(zram, index, ZRAM_INCOMPRESSIBLE);
-	clear_slot_flag(zram, index, ZRAM_PP_SLOT);
-	set_slot_comp_priority(zram, index, 0);
+	zram->table[index].attr.flags &= ~ZRAM_SLOT_FREE_CLEAR_MASK;
 
 	if (test_slot_flag(zram, index, ZRAM_HUGE)) {
 		/*
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 08d1774c15db..89a7e39a2f4b 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -57,6 +57,12 @@ enum zram_pageflags {
 	__NR_ZRAM_PAGEFLAGS,
 };
 
+#define ZRAM_SLOT_FREE_CLEAR_MASK	(BIT(ZRAM_IDLE) | \
+					 BIT(ZRAM_INCOMPRESSIBLE) | \
+					 BIT(ZRAM_PP_SLOT) | \
+					 (ZRAM_COMP_PRIORITY_MASK << \
+					  ZRAM_COMP_PRIORITY_BIT1))
+
 /*
  * Allocated for each disk page.  We use bit-lock (ZRAM_ENTRY_LOCK bit
  * of flags) to save memory.  There can be plenty of entries and standard
-- 
2.34.1