io-wq: fix lack of acct->nr_workers < acct->max_workers judgement

There should be this judgement before we create an io-worker

Fixes: 685fe7fe ("io-wq: eliminate the need for a manager thread")
Signed-off-by: NHao Xu <haoxu@linux.alibaba.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io-wq.c

@@ -280,9 +280,17 @@ static void create_worker_cb(struct callback_head *cb)
 {
 	struct create_worker_data *cwd;
 	struct io_wq *wq;
+	struct io_wqe *wqe;
+	struct io_wqe_acct *acct;
 
 	cwd = container_of(cb, struct create_worker_data, work);
-	wq = cwd->wqe->wq;
+	wqe = cwd->wqe;
+	wq = wqe->wq;
+	acct = &wqe->acct[cwd->index];
+	raw_spin_lock_irq(&wqe->lock);
+	if (acct->nr_workers < acct->max_workers)
+		acct->nr_workers++;
+	raw_spin_unlock_irq(&wqe->lock);
 	create_io_worker(wq, cwd->wqe, cwd->index);
 	kfree(cwd);
 }