filelock: use a consume fence in locks_inode_context()

mjguzik · brauner · commit 1fa4e69a54a2 · 2025-12-15T14:33:38.000+01:00
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. Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> Link: https://patch.msgid.link/20251203094837.290654-1-mjguzik@gmail.com Signed-off-by: Christian Brauner <brauner@kernel.org>
diff --git a/include/linux/filelock.h b/include/linux/filelock.h
@@ -241,7 +241,10 @@ 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 */

Original file line number	Diff line number	Diff line change
`@@ -241,7 +241,10 @@ bool locks_owner_has_blockers(struct file_lock_context *flctx,`
`241`	`241`	`static inline struct file_lock_context *`
`242`	`242`	`locks_inode_context(const struct inode *inode)`
`243`	`243`	`{`
`244`		`- return smp_load_acquire(&inode->i_flctx);`
	`244`	`+ /*`
	`245`	`+ * Paired with the fence in locks_get_lock_context().`
	`246`	`+ */`
	`247`	`+ return READ_ONCE(inode->i_flctx);`
`245`	`248`	`}`
`246`	`249`
`247`	`250`	`#else /* !CONFIG_FILE_LOCKING */`