io_uring: optimise hot path of ltimeout prep

io_prep_linked_timeout() grew too heavy and compiler now refuse to
inline the function. Help it by splitting in two and annotating with
inline.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/560636717a32e9513724f09b9ecaace942dde4d4.1628705069.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1046,7 +1046,6 @@ static bool io_cqring_fill_event(struct io_ring_ctx *ctx, u64 user_data,
 static void io_put_req(struct io_kiocb *req);
 static void io_put_req_deferred(struct io_kiocb *req);
 static void io_dismantle_req(struct io_kiocb *req);
-static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req);
 static void io_queue_linked_timeout(struct io_kiocb *req);
 static int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type,
 				     struct io_uring_rsrc_update2 *up,
@@ -1299,6 +1298,31 @@ static void io_req_track_inflight(struct io_kiocb *req)
 	}
 }
 
+static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
+{
+	struct io_kiocb *nxt = req->link;
+
+	if (req->flags & REQ_F_LINK_TIMEOUT)
+		return NULL;
+
+	/* linked timeouts should have two refs once prep'ed */
+	io_req_refcount(req);
+	io_req_refcount(nxt);
+	req_ref_get(nxt);
+
+	nxt->timeout.head = req;
+	nxt->flags |= REQ_F_LTIMEOUT_ACTIVE;
+	req->flags |= REQ_F_LINK_TIMEOUT;
+	return nxt;
+}
+
+static inline struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
+{
+	if (likely(!req->link || req->link->opcode != IORING_OP_LINK_TIMEOUT))
+		return NULL;
+	return __io_prep_linked_timeout(req);
+}
+
 static void io_prep_async_work(struct io_kiocb *req)
 {
 	const struct io_op_def *def = &io_op_defs[req->opcode];
@@ -6453,25 +6477,6 @@ static void io_queue_linked_timeout(struct io_kiocb *req)
 	io_put_req(req);
 }
 
-static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
-{
-	struct io_kiocb *nxt = req->link;
-
-	if (!nxt || (req->flags & REQ_F_LINK_TIMEOUT) ||
-	    nxt->opcode != IORING_OP_LINK_TIMEOUT)
-		return NULL;
-
-	/* linked timeouts should have two refs once prep'ed */
-	io_req_refcount(req);
-	io_req_refcount(nxt);
-	req_ref_get(nxt);
-
-	nxt->timeout.head = req;
-	nxt->flags |= REQ_F_LTIMEOUT_ACTIVE;
-	req->flags |= REQ_F_LINK_TIMEOUT;
-	return nxt;
-}
-
 static void __io_queue_sqe(struct io_kiocb *req)
 	__must_hold(&req->ctx->uring_lock)
 {