linux-kernel - [PATCH 1/2] filelock: use a consume fence in locks_inode

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Message-ID: <20251109172516.1317329-1-mjguzik@gmail.com>
Date: Sun,  9 Nov 2025 18:25:15 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: brauner@...nel.org,
	jlayton@...nel.org
Cc: viro@...iv.linux.org.uk,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>
Subject: [PATCH 1/2] filelock: use a consume fence in locks_inode_context()

Matches the idiom of storing a pointer with a release fence and safely
getting the content with a consume fence after.

Eliminates an actual fence on some archs.

Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
---

this is tiny prep for the actual change later

 include/linux/filelock.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/filelock.h b/include/linux/filelock.h
index c2ce8ba05d06..37e1b33bd267 100644
--- a/include/linux/filelock.h
+++ b/include/linux/filelock.h
@@ -232,7 +232,10 @@ bool locks_owner_has_blockers(struct file_lock_context *flctx,
 static inline struct file_lock_context *
 locks_inode_context(const struct inode *inode)
 {
-	return smp_load_acquire(&inode->i_flctx);
+	/*
+	 * Paired with the fence in locks_get_lock_context().
+	 */
+	return READ_ONCE(inode->i_flctx);
 }
 
 #else /* !CONFIG_FILE_LOCKING */
-- 
2.48.1