io_uring: avoid unnecessary io_wq_work copy for fast poll feature

to #28736503 commit 405a5d2 upstream Basically IORING_OP_POLL_ADD command and async armed poll handlers for regular commands don't touch io_wq_work, so only REQ_F_WORK_INITIALIZED is set, can we do io_wq_work copy and restore. Signed-off-by: Xiaoguang Wang <[email protected]> Acked-by: Joseph Qi <[email protected]> Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Xiaoguang Wang <[email protected]> Acked-by: Joseph Qi <[email protected]>
alibaba · Jun 29, 2020 · b260773 · b260773
1 parent cfbe7e8
commit b260773
Showing 1 changed file with 9 additions and 4 deletions.
diff --git a/fs/io_uring.c b/fs/io_uring.c
@@ -4254,7 +4254,8 @@ static void io_async_task_func(struct callback_head *cb)
 	spin_unlock_irq(&ctx->completion_lock);
 
 	/* restore ->work in case we need to retry again */
-	memcpy(&req->work, &apoll->work, sizeof(req->work));
+	if (req->flags & REQ_F_WORK_INITIALIZED)
+		memcpy(&req->work, &apoll->work, sizeof(req->work));
 	kfree(apoll);
 
 	if (!canceled) {
@@ -4351,7 +4352,8 @@ static bool io_arm_poll_handler(struct io_kiocb *req)
 		return false;
 
 	req->flags |= REQ_F_POLLED;
-	memcpy(&apoll->work, &req->work, sizeof(req->work));
+	if (req->flags & REQ_F_WORK_INITIALIZED)
+		memcpy(&apoll->work, &req->work, sizeof(req->work));
 	had_io = req->io != NULL;
 
 	get_task_struct(current);
@@ -4376,7 +4378,8 @@ static bool io_arm_poll_handler(struct io_kiocb *req)
 		if (!had_io)
 			io_poll_remove_double(req);
 		spin_unlock_irq(&ctx->completion_lock);
-		memcpy(&req->work, &apoll->work, sizeof(req->work));
+		if (req->flags & REQ_F_WORK_INITIALIZED)
+			memcpy(&req->work, &apoll->work, sizeof(req->work));
 		kfree(apoll);
 		return false;
 	}
@@ -4421,7 +4424,9 @@ static bool io_poll_remove_one(struct io_kiocb *req)
 			 * io_req_work_drop_env below when dropping the
 			 * final reference.
 			 */
-			memcpy(&req->work, &apoll->work, sizeof(req->work));
+			if (req->flags & REQ_F_WORK_INITIALIZED)
+				memcpy(&req->work, &apoll->work,
+				       sizeof(req->work));
 			kfree(apoll);
 		}
 	}