linux-kernel - [PATCH] zram: do not set ZRAM_IDLE bit for idlepage writeback in writeback

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Date:   Tue, 21 Jan 2020 19:35:57 +0800
From:   Yue Hu <zbestahu@...il.com>
To:     minchan@...nel.org, ngupta@...are.org,
        sergey.senozhatsky.work@...il.com
Cc:     linux-kernel@...r.kernel.org, huyue2@...ong.com
Subject: [PATCH] zram: do not set ZRAM_IDLE bit for idlepage writeback in writeback_store()

From: Yue Hu <huyue2@...ong.com>

Currently, we will call zram_set_flag() to set ZRAM_IDLE bit even for
idlepage writeback. That is pointless. Let's set it only for hugepage mode.

Signed-off-by: Yue Hu <huyue2@...ong.com>
---
 drivers/block/zram/zram_drv.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 4285e75..eef5767 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -689,16 +689,18 @@ static ssize_t writeback_store(struct device *dev,
 		if (mode == IDLE_WRITEBACK &&
 			  !zram_test_flag(zram, index, ZRAM_IDLE))
 			goto next;
-		if (mode == HUGE_WRITEBACK &&
-			  !zram_test_flag(zram, index, ZRAM_HUGE))
-			goto next;
+		if (mode == HUGE_WRITEBACK) {
+			if (!zram_test_flag(zram, index, ZRAM_HUGE))
+				goto next;
+			/* Need for hugepage writeback racing */
+			zram_set_flag(zram, index, ZRAM_IDLE);
+		}
+
 		/*
 		 * Clearing ZRAM_UNDER_WB is duty of caller.
 		 * IOW, zram_free_page never clear it.
 		 */
 		zram_set_flag(zram, index, ZRAM_UNDER_WB);
-		/* Need for hugepage writeback racing */
-		zram_set_flag(zram, index, ZRAM_IDLE);
 		zram_slot_unlock(zram, index);
 		if (zram_bvec_read(zram, &bvec, index, 0, NULL)) {
 			zram_slot_lock(zram, index);
-- 
1.9.1