io_uring: don't re-setup vecs/iter in io_resumit_prep() is already there

If we already have mapped the necessary data for retry, then don't set
it up again. It's a pointless operation, and we leak the iovec if it's
a large (non-stack) vec.

Fixes: b63534c4 ("io_uring: re-issue block requests that failed because of resources")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -2294,6 +2294,7 @@ static bool io_resubmit_prep(struct io_kiocb *req, int error)
 		goto end_req;
 	}
 
+	if (!req->io) {
 		ret = io_import_iovec(rw, req, &iovec, &iter, false);
 		if (ret < 0)
 			goto end_req;
@@ -2301,6 +2302,9 @@ static bool io_resubmit_prep(struct io_kiocb *req, int error)
 		if (!ret)
 			return true;
 		kfree(iovec);
+	} else {
+		return true;
+	}
 end_req:
 	req_set_fail_links(req);
 	io_req_complete(req, ret);