io_uring: refactor io_req_find_next

Move the fast path from io_req_find_next() into callers. It prepares us
for further changes.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/10bd0e564472dde0c7f8d90ae317d05356cd565a.1647897811.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -2370,8 +2370,6 @@ static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
 {
 	struct io_kiocb *nxt;
 
-	if (likely(!(req->flags & (REQ_F_LINK|REQ_F_HARDLINK))))
-		return NULL;
 	/*
 	 * If LINK is set, we have dependent requests in this chain. If we
 	 * didn't fail this request, queue the first one up, moving any other
@@ -2598,10 +2596,12 @@ static void io_req_task_queue_reissue(struct io_kiocb *req)
 
 static inline void io_queue_next(struct io_kiocb *req)
 {
-	struct io_kiocb *nxt = io_req_find_next(req);
+	if (unlikely(req->flags & (REQ_F_LINK|REQ_F_HARDLINK))) {
+		struct io_kiocb *nxt = io_req_find_next(req);
 
-	if (nxt)
-		io_req_task_queue(nxt);
+		if (nxt)
+			io_req_task_queue(nxt);
+	}
 }
 
 static void io_free_req(struct io_kiocb *req)
@@ -2695,7 +2695,8 @@ static inline struct io_kiocb *io_put_req_find_next(struct io_kiocb *req)
 	struct io_kiocb *nxt = NULL;
 
 	if (req_ref_put_and_test(req)) {
-		nxt = io_req_find_next(req);
+		if (unlikely(req->flags & (REQ_F_LINK|REQ_F_HARDLINK)))
+			nxt = io_req_find_next(req);
 		__io_free_req(req);
 	}
 	return nxt;