Re: [PATCH v9 13/17] fuse: Allow to queue fg requests through io-uring

[Bernd Schubert <bernd@bsbernd.com>]

> +/* queue a fuse request and send it if a ring entry is available */
> +void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req)
> +{
> +	struct fuse_conn *fc = req->fm->fc;
> +	struct fuse_ring *ring = fc->ring;
> +	struct fuse_ring_queue *queue;
> +	struct fuse_ring_ent *ent = NULL;
> +	int err;
> +
> +	err = -EINVAL;
> +	queue = fuse_uring_task_to_queue(ring);
> +	if (!queue)
> +		goto err;
> +
> +	if (req->in.h.opcode != FUSE_NOTIFY_REPLY)
> +		req->in.h.unique = fuse_get_unique(fiq);
> +
> +	spin_lock(&queue->lock);
> +	err = -ENOTCONN;
> +	if (unlikely(queue->stopped))
> +		goto err_unlock;
> +
> +	ent = list_first_entry_or_null(&queue->ent_avail_queue,
> +				       struct fuse_ring_ent, list);
> +	if (ent)
> +		fuse_uring_add_req_to_ring_ent(ent, req);
> +	else
> +		list_add_tail(&req->list, &queue->fuse_req_queue);
> +	spin_unlock(&queue->lock);
> +
> +	if (ent) {
> +		struct io_uring_cmd *cmd = ent->cmd;
> +
> +		err = -EIO;
> +		if (WARN_ON_ONCE(ent->state != FRRS_FUSE_REQ))
> +			goto err;


I noticed this - this is wrong, as ent would be in nirvana state if
this condition would ever happen.