io_uring: use kmemdup instead of kmalloc and memcpy

commit 954dab193d19cbbff8f83b58c9360bf00ddb273c upstream.

Just clean up the code, no function changes.
Signed-off-by: NJackie Liu <liuyun01@kylinos.cn>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>

fs/io_uring.c

@@ -2097,13 +2097,11 @@ static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) {
 		struct io_uring_sqe *sqe_copy;
 
-		sqe_copy = kmalloc(sizeof(*sqe_copy), GFP_KERNEL);
+		sqe_copy = kmemdup(s->sqe, sizeof(*sqe_copy), GFP_KERNEL);
 		if (sqe_copy) {
 			struct async_list *list;
 
-			memcpy(sqe_copy, s->sqe, sizeof(*sqe_copy));
 			s->sqe = sqe_copy;
-
 			memcpy(&req->submit, s, sizeof(*s));
 			list = io_async_list_from_sqe(ctx, s->sqe);
 			if (!io_add_to_prev_work(list, req)) {