Re: [PATCH 2/7] fuse: flush pending fuse events before aborting the connection

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Jul 18, 2025 at 08:07:30PM +0200, Bernd Schubert wrote:
> 
> > 
> > Please see the two attached patches, which are needed for fuse-io-uring.
> > I can also send them separately, if you prefer.
> 
> We (actually Horst) is just testing it as Horst sees failing xfs tests in
> our branch with tmp page removal
> 
> Patch 2 needs this addition (might be more, as I didn't test). 
> I had it in first, but then split the patch and missed that.

Aha, I noticed that the flush didn't quite work when uring was enabled.
I don't generally enable uring for testing because I already wrote a lot
of shaky code and uring support is new.

Though I'm afraid I have no opinion on this, because I haven't looked
deeply into dev_uring.c.

--D

> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index eca457d1005e..acf11eadbf3b 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -123,6 +123,9 @@ void fuse_uring_flush_bg(struct fuse_conn *fc)
>         struct fuse_ring_queue *queue;
>         struct fuse_ring *ring = fc->ring;
>  
> +       if (!ring)
> +               return;
> +
>         for (qid = 0; qid < ring->nr_queues; qid++) {
>                 queue = READ_ONCE(ring->queues[qid]);
>                 if (!queue)
> 
> 

> fuse: Refactor io-uring bg queue flush and queue abort
> 
> From: Bernd Schubert <bschubert@ddn.com>
> 
> This is a preparation to allow fuse-io-uring bg queue
> flush from flush_bg_queue()
> 
> This does two function renames:
> fuse_uring_flush_bg -> fuse_uring_flush_queue_bg
> fuse_uring_abort_end_requests -> fuse_uring_flush_bg
> 
> And fuse_uring_abort_end_queue_requests() is moved to
> fuse_uring_stop_queues().
> 
> Signed-off-by: Bernd Schubert <bschubert@ddn.com>
> ---
>  fs/fuse/dev_uring.c   |   14 +++++++-------
>  fs/fuse/dev_uring_i.h |    4 ++--
>  2 files changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index 249b210becb1..eca457d1005e 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -47,7 +47,7 @@ static struct fuse_ring_ent *uring_cmd_to_ring_ent(struct io_uring_cmd *cmd)
>  	return pdu->ent;
>  }
>  
> -static void fuse_uring_flush_bg(struct fuse_ring_queue *queue)
> +static void fuse_uring_flush_queue_bg(struct fuse_ring_queue *queue)
>  {
>  	struct fuse_ring *ring = queue->ring;
>  	struct fuse_conn *fc = ring->fc;
> @@ -88,7 +88,7 @@ static void fuse_uring_req_end(struct fuse_ring_ent *ent, struct fuse_req *req,
>  	if (test_bit(FR_BACKGROUND, &req->flags)) {
>  		queue->active_background--;
>  		spin_lock(&fc->bg_lock);
> -		fuse_uring_flush_bg(queue);
> +		fuse_uring_flush_queue_bg(queue);
>  		spin_unlock(&fc->bg_lock);
>  	}
>  
> @@ -117,11 +117,11 @@ static void fuse_uring_abort_end_queue_requests(struct fuse_ring_queue *queue)
>  	fuse_dev_end_requests(&req_list);
>  }
>  
> -void fuse_uring_abort_end_requests(struct fuse_ring *ring)
> +void fuse_uring_flush_bg(struct fuse_conn *fc)
>  {
>  	int qid;
>  	struct fuse_ring_queue *queue;
> -	struct fuse_conn *fc = ring->fc;
> +	struct fuse_ring *ring = fc->ring;
>  
>  	for (qid = 0; qid < ring->nr_queues; qid++) {
>  		queue = READ_ONCE(ring->queues[qid]);
> @@ -133,10 +133,9 @@ void fuse_uring_abort_end_requests(struct fuse_ring *ring)
>  		WARN_ON_ONCE(ring->fc->max_background != UINT_MAX);
>  		spin_lock(&queue->lock);
>  		spin_lock(&fc->bg_lock);
> -		fuse_uring_flush_bg(queue);
> +		fuse_uring_flush_queue_bg(queue);
>  		spin_unlock(&fc->bg_lock);
>  		spin_unlock(&queue->lock);
> -		fuse_uring_abort_end_queue_requests(queue);
>  	}
>  }
>  
> @@ -475,6 +474,7 @@ void fuse_uring_stop_queues(struct fuse_ring *ring)
>  		if (!queue)
>  			continue;
>  
> +		fuse_uring_abort_end_queue_requests(queue);
>  		fuse_uring_teardown_entries(queue);
>  	}
>  
> @@ -1326,7 +1326,7 @@ bool fuse_uring_queue_bq_req(struct fuse_req *req)
>  	fc->num_background++;
>  	if (fc->num_background == fc->max_background)
>  		fc->blocked = 1;
> -	fuse_uring_flush_bg(queue);
> +	fuse_uring_flush_queue_bg(queue);
>  	spin_unlock(&fc->bg_lock);
>  
>  	/*
> diff --git a/fs/fuse/dev_uring_i.h b/fs/fuse/dev_uring_i.h
> index 51a563922ce1..55f52508de3c 100644
> --- a/fs/fuse/dev_uring_i.h
> +++ b/fs/fuse/dev_uring_i.h
> @@ -138,7 +138,7 @@ struct fuse_ring {
>  bool fuse_uring_enabled(void);
>  void fuse_uring_destruct(struct fuse_conn *fc);
>  void fuse_uring_stop_queues(struct fuse_ring *ring);
> -void fuse_uring_abort_end_requests(struct fuse_ring *ring);
> +void fuse_uring_flush_bg(struct fuse_conn *fc);
>  int fuse_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags);
>  void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req);
>  bool fuse_uring_queue_bq_req(struct fuse_req *req);
> @@ -153,7 +153,7 @@ static inline void fuse_uring_abort(struct fuse_conn *fc)
>  		return;
>  
>  	if (atomic_read(&ring->queue_refs) > 0) {
> -		fuse_uring_abort_end_requests(ring);
> +		fuse_uring_flush_bg(fc);
>  		fuse_uring_stop_queues(ring);
>  	}
>  }

> fuse: Flush the io-uring bg queue from fuse_uring_flush_bg
> 
> From: Bernd Schubert <bschubert@ddn.com>
> 
> This is useful to have a unique API to flush background requests.
> For example when the bg queue gets flushed before
> the remaining of fuse_conn_destroy().
> 
> Signed-off-by: Bernd Schubert <bschubert@ddn.com>
> ---
>  fs/fuse/dev.c         |    2 ++
>  fs/fuse/dev_uring.c   |    3 +++
>  fs/fuse/dev_uring_i.h |   10 +++++++---
>  3 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index 5387e4239d6a..3f5f168cc28a 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -426,6 +426,8 @@ static void flush_bg_queue(struct fuse_conn *fc)
>  		fc->active_background++;
>  		fuse_send_one(fiq, req);
>  	}
> +
> +	fuse_uring_flush_bg(fc);
>  }
>  
>  /*
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index eca457d1005e..acf11eadbf3b 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -123,6 +123,9 @@ void fuse_uring_flush_bg(struct fuse_conn *fc)
>  	struct fuse_ring_queue *queue;
>  	struct fuse_ring *ring = fc->ring;
>  
> +	if (!ring)
> +		return;
> +
>  	for (qid = 0; qid < ring->nr_queues; qid++) {
>  		queue = READ_ONCE(ring->queues[qid]);
>  		if (!queue)
> diff --git a/fs/fuse/dev_uring_i.h b/fs/fuse/dev_uring_i.h
> index 55f52508de3c..fca2184e8d94 100644
> --- a/fs/fuse/dev_uring_i.h
> +++ b/fs/fuse/dev_uring_i.h
> @@ -152,10 +152,10 @@ static inline void fuse_uring_abort(struct fuse_conn *fc)
>  	if (ring == NULL)
>  		return;
>  
> -	if (atomic_read(&ring->queue_refs) > 0) {
> -		fuse_uring_flush_bg(fc);
> +	/* Assumes bg queues were already flushed before */
> +
> +	if (atomic_read(&ring->queue_refs) > 0)
>  		fuse_uring_stop_queues(ring);
> -	}
>  }
>  
>  static inline void fuse_uring_wait_stopped_queues(struct fuse_conn *fc)
> @@ -206,6 +206,10 @@ static inline bool fuse_uring_request_expired(struct fuse_conn *fc)
>  	return false;
>  }
>  
> +static inline void fuse_uring_flush_bg(struct fuse_conn *fc)
> +{
> +}
> +
>  #endif /* CONFIG_FUSE_IO_URING */
>  
>  #endif /* _FS_FUSE_DEV_URING_I_H */