Re: [PATCH v3 1/6] fuse: {io-uring} Add queue length counters

[Luis Henriques <luis@igalia.com>]

On Mon, Oct 13 2025, Bernd Schubert wrote:

> This is another preparation and will be used for decision
> which queue to add a request to.

Just a very small nit: "This is another preparation..." -- this is the
first patch in the series, so it makes more sense to have this sentence in
the second patch instead.  I guess the patches got reordered at some point
and the wording didn't got updated accordingly.

Cheers,
-- 
Luís

>
> Signed-off-by: Bernd Schubert <bschubert@ddn.com>
> Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
> ---
>  fs/fuse/dev_uring.c   | 17 +++++++++++++++--
>  fs/fuse/dev_uring_i.h |  3 +++
>  2 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index f6b12aebb8bbe7d255980593b75b5fb5af9c669e..872ae17ffaf49a30c46ef89c1668684a61a0cce4 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -86,13 +86,13 @@ static void fuse_uring_req_end(struct fuse_ring_ent *ent, struct fuse_req *req,
>  	lockdep_assert_not_held(&queue->lock);
>  	spin_lock(&queue->lock);
>  	ent->fuse_req = NULL;
> +	queue->nr_reqs--;
>  	if (test_bit(FR_BACKGROUND, &req->flags)) {
>  		queue->active_background--;
>  		spin_lock(&fc->bg_lock);
>  		fuse_uring_flush_bg(queue);
>  		spin_unlock(&fc->bg_lock);
>  	}
> -
>  	spin_unlock(&queue->lock);
>  
>  	if (error)
> @@ -112,6 +112,7 @@ static void fuse_uring_abort_end_queue_requests(struct fuse_ring_queue *queue)
>  	list_for_each_entry(req, &queue->fuse_req_queue, list)
>  		clear_bit(FR_PENDING, &req->flags);
>  	list_splice_init(&queue->fuse_req_queue, &req_list);
> +	queue->nr_reqs = 0;
>  	spin_unlock(&queue->lock);
>  
>  	/* must not hold queue lock to avoid order issues with fi->lock */
> @@ -1280,10 +1281,13 @@ void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req)
>  	req->ring_queue = queue;
>  	ent = list_first_entry_or_null(&queue->ent_avail_queue,
>  				       struct fuse_ring_ent, list);
> +	queue->nr_reqs++;
> +
>  	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)
> @@ -1319,6 +1323,7 @@ bool fuse_uring_queue_bq_req(struct fuse_req *req)
>  	set_bit(FR_URING, &req->flags);
>  	req->ring_queue = queue;
>  	list_add_tail(&req->list, &queue->fuse_req_bg_queue);
> +	queue->nr_reqs++;
>  
>  	ent = list_first_entry_or_null(&queue->ent_avail_queue,
>  				       struct fuse_ring_ent, list);
> @@ -1351,8 +1356,16 @@ bool fuse_uring_queue_bq_req(struct fuse_req *req)
>  bool fuse_uring_remove_pending_req(struct fuse_req *req)
>  {
>  	struct fuse_ring_queue *queue = req->ring_queue;
> +	bool removed = fuse_remove_pending_req(req, &queue->lock);
>  
> -	return fuse_remove_pending_req(req, &queue->lock);
> +	if (removed) {
> +		/* Update counters after successful removal */
> +		spin_lock(&queue->lock);
> +		queue->nr_reqs--;
> +		spin_unlock(&queue->lock);
> +	}
> +
> +	return removed;
>  }
>  
>  static const struct fuse_iqueue_ops fuse_io_uring_ops = {
> diff --git a/fs/fuse/dev_uring_i.h b/fs/fuse/dev_uring_i.h
> index 51a563922ce14158904a86c248c77767be4fe5ae..c63bed9f863d53d4ac2bed7bfbda61941cd99083 100644
> --- a/fs/fuse/dev_uring_i.h
> +++ b/fs/fuse/dev_uring_i.h
> @@ -94,6 +94,9 @@ struct fuse_ring_queue {
>  	/* background fuse requests */
>  	struct list_head fuse_req_bg_queue;
>  
> +	/* number of requests queued or in userspace */
> +	unsigned int nr_reqs;
> +
>  	struct fuse_pqueue fpq;
>  
>  	unsigned int active_background;
>
> -- 
> 2.43.0
>