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From:   Kemeng Shi <shikemeng@huaweicloud.com>
To:     miklos@szeredi.hu, bernd.schubert@fastmail.fm
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2] fuse: remove unneeded lock which protecting update of congestion_threshold
Date:   Sat,  7 Oct 2023 23:39:56 +0800
Message-Id: <20231007153956.344794-1-shikemeng@huaweicloud.com>
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Commit 670d21c6e17f6 ("fuse: remove reliance on bdi congestion") change how
congestion_threshold is used and lock in
fuse_conn_congestion_threshold_write is not needed anymore.
1. Access to supe_block is removed along with removing of bdi congestion.
Then down_read(&fc->killsb) which protecting access to super_block is no
needed.
2. Compare num_background and congestion_threshold without holding
bg_lock. Then there is no need to hold bg_lock to update
congestion_threshold.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
---
 fs/fuse/control.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index ab62e4624256..1bf928e277fe 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -174,11 +174,7 @@ static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
 	if (!fc)
 		goto out;
 
-	down_read(&fc->killsb);
-	spin_lock(&fc->bg_lock);
-	fc->congestion_threshold = val;
-	spin_unlock(&fc->bg_lock);
-	up_read(&fc->killsb);
+	WRITE_ONCE(fc->congestion_threshold, val);
 	fuse_conn_put(fc);
 out:
 	return ret;
-- 
2.30.0