linux-kernel - [PATCH] fuse: remove unneeded lock which protecting update of congestion

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Message-Id: <20230914154553.71939-1-shikemeng@huaweicloud.com>
Date:   Thu, 14 Sep 2023 23:45:53 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     miklos@...redi.hu, bernd.schubert@...tmail.fm,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] fuse: remove unneeded lock which protecting update of congestion_threshold

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@...weicloud.com>
---
 fs/fuse/control.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index 247ef4f76761..c5d7bf80efed 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);
 	fuse_conn_put(fc);
 out:
 	return ret;
-- 
2.30.0