io_uring: return boolean value for io_alloc_async_data

boolean value is good enough for io_alloc_async_data.
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20210922101522.9179-1-haoxu@linux.alibaba.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -3301,7 +3301,7 @@ static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
 	}
 }
 
-static inline int io_alloc_async_data(struct io_kiocb *req)
+static inline bool io_alloc_async_data(struct io_kiocb *req)
 {
 	WARN_ON_ONCE(!io_op_defs[req->opcode].async_size);
 	req->async_data = kmalloc(io_op_defs[req->opcode].async_size, GFP_KERNEL);