io-wq: reorder cancellation pending -> running

Go all over all pending lists and cancel works there, and only then
try to match running requests. No functional changes here, just a
preparation for bulk cancellation.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io-wq.c

@@ -927,7 +927,7 @@ static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
 	return ret;
 }
 
-static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
+static bool io_wqe_cancel_pending_work(struct io_wqe *wqe,
 				       struct io_cb_cancel_data *match)
 {
 	struct io_wq_work_node *node, *prev;
@@ -935,11 +935,6 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 	unsigned long flags;
 	bool found = false;
 
-	/*
-	 * First check pending list, if we're lucky we can just remove it
-	 * from there. CANCEL_OK means that the work is returned as-new,
-	 * no completion will be posted for it.
-	 */
 	spin_lock_irqsave(&wqe->lock, flags);
 	wq_list_for_each(node, prev, &wqe->work_list) {
 		work = container_of(node, struct io_wq_work, list);
@@ -952,21 +947,20 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 	}
 	spin_unlock_irqrestore(&wqe->lock, flags);
 
-	if (found) {
+	if (found)
 		io_run_cancel(work, wqe);
-		return IO_WQ_CANCEL_OK;
-	}
+	return found;
+}
+
+static bool io_wqe_cancel_running_work(struct io_wqe *wqe,
+				       struct io_cb_cancel_data *match)
+{
+	bool found;
 
-	/*
-	 * Now check if a free (going busy) or busy worker has the work
-	 * currently running. If we find it there, we'll return CANCEL_RUNNING
-	 * as an indication that we attempt to signal cancellation. The
-	 * completion will run normally in this case.
-	 */
 	rcu_read_lock();
 	found = io_wq_for_each_worker(wqe, io_wq_worker_cancel, match);
 	rcu_read_unlock();
-	return found ? IO_WQ_CANCEL_RUNNING : IO_WQ_CANCEL_NOTFOUND;
+	return found;
 }
 
 enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
@@ -976,18 +970,34 @@ enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
 		.fn	= cancel,
 		.data	= data,
 	};
-	enum io_wq_cancel ret = IO_WQ_CANCEL_NOTFOUND;
 	int node;
 
+	/*
+	 * First check pending list, if we're lucky we can just remove it
+	 * from there. CANCEL_OK means that the work is returned as-new,
+	 * no completion will be posted for it.
+	 */
+	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
+
+		if (io_wqe_cancel_pending_work(wqe, &match))
+			return IO_WQ_CANCEL_OK;
+	}
+
+	/*
+	 * Now check if a free (going busy) or busy worker has the work
+	 * currently running. If we find it there, we'll return CANCEL_RUNNING
+	 * as an indication that we attempt to signal cancellation. The
+	 * completion will run normally in this case.
+	 */
 	for_each_node(node) {
 		struct io_wqe *wqe = wq->wqes[node];
 
-		ret = io_wqe_cancel_work(wqe, &match);
-		if (ret != IO_WQ_CANCEL_NOTFOUND)
-			break;
+		if (io_wqe_cancel_running_work(wqe, &match))
+			return IO_WQ_CANCEL_RUNNING;
 	}
 
-	return ret;
+	return IO_WQ_CANCEL_NOTFOUND;
 }
 
 static bool io_wq_io_cb_cancel_data(struct io_wq_work *work, void *data)