landlock: Improve variable scope

This is now possible thanks to the disconnected directory fix.

Cc: Günther Noack <gnoack@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/20251128172200.760753-3-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>

Author: l0kod

security/landlock/fs.c

@@ -838,7 +838,6 @@ static bool is_access_to_paths_allowed(
 	 * restriction.
 	 */
 	while (true) {
-		struct dentry *parent_dentry;
 		const struct landlock_rule *rule;
 
 		/*
@@ -931,7 +930,9 @@ static bool is_access_to_paths_allowed(
 			walker_path.dentry = walker_path.mnt->mnt_root;
 			dget(walker_path.dentry);
 		} else {
-			parent_dentry = dget_parent(walker_path.dentry);
+			struct dentry *const parent_dentry =
+				dget_parent(walker_path.dentry);
+
 			dput(walker_path.dentry);
 			walker_path.dentry = parent_dentry;
 		}