netfs: Make netfs_put_request() handle a NULL pointer

Make netfs_put_request() just return if given a NULL request pointer.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org

fs/netfs/objects.c

@@ -106,10 +106,12 @@ static void netfs_free_request(struct work_struct *work)
 void netfs_put_request(struct netfs_io_request *rreq, bool was_async,
 		       enum netfs_rreq_ref_trace what)
 {
-	unsigned int debug_id = rreq->debug_id;
+	unsigned int debug_id;
 	bool dead;
 	int r;
 
+	if (rreq) {
+		debug_id = rreq->debug_id;
 		dead = __refcount_dec_and_test(&rreq->ref, &r);
 		trace_netfs_rreq_ref(debug_id, r - 1, what);
 		if (dead) {
@@ -121,6 +123,7 @@ void netfs_put_request(struct netfs_io_request *rreq, bool was_async,
 				netfs_free_request(&rreq->work);
 			}
 		}
+	}
 }
 
 /*