io_uring: don't pass def into io_req_work_grab_env

Remove struct io_op_def *def parameter from io_req_work_grab_env(),
it's trivially deducible from req->opcode and fast. The API is
cleaner this way, and also helps the complier to understand
that it's a real constant and could be register-cached.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1101,9 +1101,10 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx)
 	}
 }
 
-static inline void io_req_work_grab_env(struct io_kiocb *req,
-					const struct io_op_def *def)
+static inline void io_req_work_grab_env(struct io_kiocb *req)
 {
+	const struct io_op_def *def = &io_op_defs[req->opcode];
+
 	if (!req->work.mm && def->needs_mm) {
 		mmgrab(current->mm);
 		req->work.mm = current->mm;
@@ -1161,7 +1162,7 @@ static inline void io_prep_async_work(struct io_kiocb *req,
 	}
 
 	io_req_init_async(req);
-	io_req_work_grab_env(req, def);
+	io_req_work_grab_env(req);
 
 	*link = io_prep_linked_timeout(req);
 }
@@ -5255,7 +5256,7 @@ static int io_req_defer_prep(struct io_kiocb *req,
 
 	if (for_async || (req->flags & REQ_F_WORK_INITIALIZED)) {
 		io_req_init_async(req);
-		io_req_work_grab_env(req, &io_op_defs[req->opcode]);
+		io_req_work_grab_env(req);
 	}
 
 	switch (req->opcode) {