io_uring: don't add non-IO requests to iopoll pending list

We normally disable any commands that aren't specifically poll commands
for a ring that is setup for polling, but we do allow buffer provide and
remove commands to support buffer selection for polled IO. Once a
request is issued, we add it to the poll list to poll for completion. But
we should not do that for non-IO commands, as those request complete
inline immediately and aren't pollable. If we do, we can leave requests
on the iopoll list after they are freed.

Fixes: ddf0322d ("io_uring: add IORING_OP_PROVIDE_BUFFERS")
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -5306,7 +5306,8 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	if (ret)
 		return ret;
 
-	if (ctx->flags & IORING_SETUP_IOPOLL) {
+	/* If the op doesn't have a file, we're not polling for it */
+	if ((ctx->flags & IORING_SETUP_IOPOLL) && req->file) {
 		const bool in_async = io_wq_current_is_worker();
 
 		if (req->result == -EAGAIN)