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From: Mateusz Guzik <mjguzik@gmail.com>
To: brauner@kernel.org
Cc: viro@zeniv.linux.org.uk, jack@suse.cz,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Mateusz Guzik <mjguzik@gmail.com>
Subject: [PATCH v3 3/4] fs: use fput_close() in filp_close()
Date: Wed,  5 Mar 2025 13:36:43 +0100	[thread overview]
Message-ID: <20250305123644.554845-4-mjguzik@gmail.com> (raw)
In-Reply-To: <20250305123644.554845-1-mjguzik@gmail.com>

When tracing a kernel build over refcounts seen this is a wash:
@[kprobe:filp_close]:
[0]                32195 |@@@@@@@@@@                                          |
[1]               164567 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|

I verified vast majority of the skew comes from do_close_on_exec() which
could be changed to use a different variant instead.

Even without changing that, the 19.5% of calls which got here still can
save the extra atomic. Calls here are borderline non-existent compared
to fput (over 3.2 mln!), so they should not negatively affect
scalability.

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
---
 fs/open.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/open.c b/fs/open.c
index f2fcfaeb2232..bdbf03f799a1 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1551,7 +1551,7 @@ int filp_close(struct file *filp, fl_owner_t id)
 	int retval;
 
 	retval = filp_flush(filp, id);
-	fput(filp);
+	fput_close(filp);
 
 	return retval;
 }
-- 
2.43.0


  parent reply	other threads:[~2025-03-05 12:36 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-05 12:36 [RFC PATCH v3 0/4] avoid the extra atomic on a ref when closing a fd Mateusz Guzik
2025-03-05 12:36 ` [PATCH v3 1/4] file: add fput and file_ref_put routines optimized for use " Mateusz Guzik
2025-03-05 12:36 ` [PATCH v3 2/4] fs: use fput_close_sync() in close() Mateusz Guzik
2025-03-05 12:36 ` Mateusz Guzik [this message]
2025-03-05 12:36 ` [PATCH v3 4/4] fs: use fput_close() in path_openat() Mateusz Guzik
2025-03-05 17:31 ` [RFC PATCH v3 0/4] avoid the extra atomic on a ref when closing a fd Christian Brauner

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