io_uring/rw: avoid punting to io-wq directly

kiocb_done() should care to specifically redirecting requests to io-wq.
Remove the hopping to tw to then queue an io-wq, return -EAGAIN and let
the core code io_uring handle offloading.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/413564e550fe23744a970e1783dfa566291b0e6f.1710799188.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -492,7 +492,7 @@ static void io_prep_async_link(struct io_kiocb *req)
 	}
 }
 
-void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use)
+static void io_queue_iowq(struct io_kiocb *req)
 {
 	struct io_kiocb *link = io_prep_linked_timeout(req);
 	struct io_uring_task *tctx = req->task->io_uring;
@@ -1499,7 +1499,7 @@ void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts)
 	if (unlikely(req->task->flags & PF_EXITING))
 		io_req_defer_failed(req, -EFAULT);
 	else if (req->flags & REQ_F_FORCE_ASYNC)
-		io_queue_iowq(req, ts);
+		io_queue_iowq(req);
 	else
 		io_queue_sqe(req);
 }
@@ -2087,7 +2087,7 @@ static void io_queue_async(struct io_kiocb *req, int ret)
 		break;
 	case IO_APOLL_ABORTED:
 		io_kbuf_recycle(req, 0);
-		io_queue_iowq(req, NULL);
+		io_queue_iowq(req);
 		break;
 	case IO_APOLL_OK:
 		break;
@@ -2134,7 +2134,7 @@ static void io_queue_sqe_fallback(struct io_kiocb *req)
 		if (unlikely(req->ctx->drain_active))
 			io_drain_req(req);
 		else
-			io_queue_iowq(req, NULL);
+			io_queue_iowq(req);
 	}
 }
 

io_uring/io_uring.h

@@ -79,7 +79,6 @@ struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
 void __io_req_task_work_add(struct io_kiocb *req, unsigned flags);
 bool io_alloc_async_data(struct io_kiocb *req);
 void io_req_task_queue(struct io_kiocb *req);
-void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use);
 void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts);
 void io_req_task_queue_fail(struct io_kiocb *req, int ret);
 void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts);

io_uring/rw.c

@@ -187,12 +187,6 @@ static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
 	return NULL;
 }
 
-static void io_req_task_queue_reissue(struct io_kiocb *req)
-{
-	req->io_task_work.func = io_queue_iowq;
-	io_req_task_work_add(req);
-}
-
 #ifdef CONFIG_BLOCK
 static bool io_resubmit_prep(struct io_kiocb *req)
 {
@@ -405,7 +399,7 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret,
 	if (req->flags & REQ_F_REISSUE) {
 		req->flags &= ~REQ_F_REISSUE;
 		if (io_resubmit_prep(req))
-			io_req_task_queue_reissue(req);
+			return -EAGAIN;
 		else
 			io_req_task_queue_fail(req, final_ret);
 	}