io-wq: use proper nesting IRQ disabling spinlocks for cancel

We don't know what context we'll be called in for cancel, it could very
well be with IRQs disabled already. Use the IRQ saving variants of the
locking primitives.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io-wq.c

@@ -642,19 +642,20 @@ static bool io_work_cancel(struct io_worker *worker, void *cancel_data)
 {
 	struct io_cb_cancel_data *data = cancel_data;
 	struct io_wqe *wqe = data->wqe;
+	unsigned long flags;
 	bool ret = false;
 
 	/*
 	 * Hold the lock to avoid ->cur_work going out of scope, caller
 	 * may deference the passed in work.
 	 */
-	spin_lock_irq(&wqe->lock);
+	spin_lock_irqsave(&wqe->lock, flags);
 	if (worker->cur_work &&
 	    data->cancel(worker->cur_work, data->caller_data)) {
 		send_sig(SIGINT, worker->task, 1);
 		ret = true;
 	}
-	spin_unlock_irq(&wqe->lock);
+	spin_unlock_irqrestore(&wqe->lock, flags);
 
 	return ret;
 }
@@ -669,9 +670,10 @@ static enum io_wq_cancel io_wqe_cancel_cb_work(struct io_wqe *wqe,
 		.caller_data = cancel_data,
 	};
 	struct io_wq_work *work;
+	unsigned long flags;
 	bool found = false;
 
-	spin_lock_irq(&wqe->lock);
+	spin_lock_irqsave(&wqe->lock, flags);
 	list_for_each_entry(work, &wqe->work_list, list) {
 		if (cancel(work, cancel_data)) {
 			list_del(&work->list);
@@ -679,7 +681,7 @@ static enum io_wq_cancel io_wqe_cancel_cb_work(struct io_wqe *wqe,
 			break;
 		}
 	}
-	spin_unlock_irq(&wqe->lock);
+	spin_unlock_irqrestore(&wqe->lock, flags);
 
 	if (found) {
 		work->flags |= IO_WQ_WORK_CANCEL;
@@ -733,6 +735,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 					    struct io_wq_work *cwork)
 {
 	struct io_wq_work *work;
+	unsigned long flags;
 	bool found = false;
 
 	cwork->flags |= IO_WQ_WORK_CANCEL;
@@ -742,7 +745,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 	 * from there. CANCEL_OK means that the work is returned as-new,
 	 * no completion will be posted for it.
 	 */
-	spin_lock_irq(&wqe->lock);
+	spin_lock_irqsave(&wqe->lock, flags);
 	list_for_each_entry(work, &wqe->work_list, list) {
 		if (work == cwork) {
 			list_del(&work->list);
@@ -750,7 +753,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 			break;
 		}
 	}
-	spin_unlock_irq(&wqe->lock);
+	spin_unlock_irqrestore(&wqe->lock, flags);
 
 	if (found) {
 		work->flags |= IO_WQ_WORK_CANCEL;