io_uring: do io_*_prep() early in io_submit_sqe()

Now as preparations are split from async setup, we can do the first one
pretty early not spilling it across multiple call sites. And after it's
done SQE is not needed anymore and we can save on passing it deeply into
the submission stack.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -6160,22 +6160,16 @@ static int io_req_prep_async(struct io_kiocb *req)
 	return 0;
 }
 
-static int io_req_defer_prep(struct io_kiocb *req,
-			     const struct io_uring_sqe *sqe)
+static int io_req_defer_prep(struct io_kiocb *req)
 {
-	int ret;
-
-	if (!sqe)
+	if (!io_op_defs[req->opcode].needs_async_data)
 		return 0;
-	if (io_alloc_async_data(req))
-		return -EAGAIN;
-	ret = io_req_prep(req, sqe);
-	if (ret)
-		return ret;
+	/* some opcodes init it during the inital prep */
 	if (req->async_data)
-		return io_req_prep_async(req);
-	return 0;
-
+		return 0;
+	if (__io_alloc_async_data(req))
+		return -EAGAIN;
+	return io_req_prep_async(req);
 }
 
 static u32 io_get_sequence(struct io_kiocb *req)
@@ -6191,7 +6185,7 @@ static u32 io_get_sequence(struct io_kiocb *req)
 	return total_submitted - nr_reqs;
 }
 
-static int io_req_defer(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static int io_req_defer(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	struct io_defer_entry *de;
@@ -6208,11 +6202,9 @@ static int io_req_defer(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (!req_need_defer(req, seq) && list_empty_careful(&ctx->defer_list))
 		return 0;
 
-	if (!req->async_data) {
-		ret = io_req_defer_prep(req, sqe);
-		if (ret)
-			return ret;
-	}
+	ret = io_req_defer_prep(req);
+	if (ret)
+		return ret;
 	io_prep_async_link(req);
 	de = kmalloc(sizeof(*de), GFP_KERNEL);
 	if (!de)
@@ -6631,11 +6623,11 @@ static void __io_queue_sqe(struct io_kiocb *req)
 		io_queue_linked_timeout(linked_timeout);
 }
 
-static void io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static void io_queue_sqe(struct io_kiocb *req)
 {
 	int ret;
 
-	ret = io_req_defer(req, sqe);
+	ret = io_req_defer(req);
 	if (ret) {
 		if (ret != -EIOCBQUEUED) {
 fail_req:
@@ -6644,18 +6636,11 @@ static void io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 			io_req_complete(req, ret);
 		}
 	} else if (req->flags & REQ_F_FORCE_ASYNC) {
-		if (!req->async_data) {
-			ret = io_req_defer_prep(req, sqe);
-			if (unlikely(ret))
-				goto fail_req;
-		}
+		ret = io_req_defer_prep(req);
+		if (unlikely(ret))
+			goto fail_req;
 		io_queue_async_work(req);
 	} else {
-		if (sqe) {
-			ret = io_req_prep(req, sqe);
-			if (unlikely(ret))
-				goto fail_req;
-		}
 		__io_queue_sqe(req);
 	}
 }
@@ -6666,7 +6651,7 @@ static inline void io_queue_link_head(struct io_kiocb *req)
 		io_put_req(req);
 		io_req_complete(req, -ECANCELED);
 	} else
-		io_queue_sqe(req, NULL);
+		io_queue_sqe(req);
 }
 
 /*
@@ -6788,7 +6773,11 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 			link->head->flags |= REQ_F_FAIL_LINK;
 		return ret;
 	}
+	ret = io_req_prep(req, sqe);
+	if (unlikely(ret))
+		goto fail_req;
 
+	/* don't need @sqe from now on */
 	trace_io_uring_submit_sqe(ctx, req->opcode, req->user_data,
 				true, ctx->flags & IORING_SETUP_SQPOLL);
 
@@ -6813,7 +6802,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 			head->flags |= REQ_F_IO_DRAIN;
 			ctx->drain_next = 1;
 		}
-		ret = io_req_defer_prep(req, sqe);
+		ret = io_req_defer_prep(req);
 		if (unlikely(ret))
 			goto fail_req;
 		trace_io_uring_link(ctx, req, head);
@@ -6831,13 +6820,13 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 			ctx->drain_next = 0;
 		}
 		if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) {
-			ret = io_req_defer_prep(req, sqe);
+			ret = io_req_defer_prep(req);
 			if (unlikely(ret))
 				req->flags |= REQ_F_FAIL_LINK;
 			link->head = req;
 			link->last = req;
 		} else {
-			io_queue_sqe(req, sqe);
+			io_queue_sqe(req);
 		}
 	}