io_uring: kill extra iovec=NULL in import_iovec()

If io_import_iovec() returns an error, return iovec is undefined and
must not be used, so don't set it to NULL when failing.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -2826,10 +2826,8 @@ static ssize_t __io_import_iovec(int rw, struct io_kiocb *req,
 	if (opcode == IORING_OP_READ || opcode == IORING_OP_WRITE) {
 		if (req->flags & REQ_F_BUFFER_SELECT) {
 			buf = io_rw_buffer_select(req, &sqe_len, needs_lock);
-			if (IS_ERR(buf)) {
-				*iovec = NULL;
+			if (IS_ERR(buf))
 				return PTR_ERR(buf);
-			}
 			req->rw.len = sqe_len;
 		}