[PATCH 0/2] fuse: Flush io-uring bg requests

[PATCH 0/2] fuse: Flush io-uring bg requests

[Bernd Schubert]

This is on top of Darricks iomap patches and allows to flush
fuse-io-uring bg requests. We actually see busy mount points
in some xfstests and these patches seem to solve that.

https://lore.kernel.org/r/175279449501.710975.16858401145201411486.stgit@frogsfrogsfrogs

Signed-off-by: Bernd Schubert <bschubert@ddn.com>
---
Bernd Schubert (2):
      fuse: Refactor io-uring bg queue flush and queue abort
      fuse: Flush the io-uring bg queue from fuse_uring_flush_bg

 fs/fuse/dev.c         |  2 ++
 fs/fuse/dev_uring.c   | 17 ++++++++++-------
 fs/fuse/dev_uring_i.h |  8 ++++++--
 3 files changed, 18 insertions(+), 9 deletions(-)
---
base-commit: 5ef3da3900942680e3cded352be2dede505e2c26
change-id: 20250723-bg-flush-fa830835772e

Best regards,
-- 
Bernd Schubert <bschubert@ddn.com>

[PATCH 1/2] fuse: Refactor io-uring bg queue flush and queue abort

[Bernd Schubert]

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 249b210becb1cc2b40ae7b2fdf3a57dc57eaac42..eca457d1005e7ecb9d220d5092d00cf60961afea 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 51a563922ce14158904a86c248c77767be4fe5ae..55f52508de3ced624ac17fba6da1b637b1697dff 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);
 	}
 }

-- 
2.43.0

Re: [PATCH 1/2] fuse: Refactor io-uring bg queue flush and queue abort

[Joanne Koong]

On Tue, Jul 22, 2025 at 3:15 PM Bernd Schubert <bschubert@ddn.com> wrote:
>
> 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 249b210becb1cc2b40ae7b2fdf3a57dc57eaac42..eca457d1005e7ecb9d220d5092d00cf60961afea 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)

nit: i find the naming "fuse_uring_flush_bg_queue" easier to follow
than "fuse_uring_flush_queue_bg"

>  {
>         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]);

Does the "queue->stopped = true;" line inside this function need to
get moved? AFAICT, if we set queue->stopped to true here, then we're
not able to send out the request (eg fuse_uring_commit_fetch() returns
err if queue->stopped is true)


Thanks,
Joanne

> @@ -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 51a563922ce14158904a86c248c77767be4fe5ae..55f52508de3ced624ac17fba6da1b637b1697dff 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);
>         }
>  }
>
> --
> 2.43.0
>
>

[PATCH 2/2] fuse: Flush the io-uring bg queue from fuse_uring_flush_bg

[Bernd Schubert]

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 | 4 ++++
 3 files changed, 9 insertions(+)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5387e4239d6aa6f7a9780deaf581483cc28a5e68..d5f2fb82c04bf1ee7a35cb1d6d43e639270945af 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2408,6 +2408,8 @@ void fuse_flush_requests(struct fuse_conn *fc, unsigned long timeout)
 	spin_unlock(&fc->bg_lock);
 	spin_unlock(&fc->lock);
 
+	fuse_uring_flush_bg(fc);
+
 	/*
 	 * Wait 30s for all the events to complete or abort.  Touch the
 	 * watchdog once per second so that we don't trip the hangcheck timer
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index eca457d1005e7ecb9d220d5092d00cf60961afea..acf11eadbf3b6d999b310b5d8a4a6018e83cb2a9 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 55f52508de3ced624ac17fba6da1b637b1697dff..ae806dd578f26fbeac12f880cd7b6031a56aec00 100644
--- a/fs/fuse/dev_uring_i.h
+++ b/fs/fuse/dev_uring_i.h
@@ -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 */

-- 
2.43.0

Re: [PATCH 2/2] fuse: Flush the io-uring bg queue from fuse_uring_flush_bg

[Joanne Koong]

On Tue, Jul 22, 2025 at 3:42 PM Bernd Schubert <bschubert@ddn.com> wrote:
>
> 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 | 4 ++++
>  3 files changed, 9 insertions(+)
>
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index 5387e4239d6aa6f7a9780deaf581483cc28a5e68..d5f2fb82c04bf1ee7a35cb1d6d43e639270945af 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -2408,6 +2408,8 @@ void fuse_flush_requests(struct fuse_conn *fc, unsigned long timeout)
>         spin_unlock(&fc->bg_lock);
>         spin_unlock(&fc->lock);
>
> +       fuse_uring_flush_bg(fc);

I think we'll need to get rid of the
"WARN_ON_ONCE(ring->fc->max_background != UINT_MAX);" in
fuse_uring_flush_bg() since fuse_flush_requests() sets
fc->max_background to UINT_MAX a few lines above before making this
call.


Thanks,
Joanne

> +
>         /*
>          * Wait 30s for all the events to complete or abort.  Touch the
>          * watchdog once per second so that we don't trip the hangcheck timer
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index eca457d1005e7ecb9d220d5092d00cf60961afea..acf11eadbf3b6d999b310b5d8a4a6018e83cb2a9 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 55f52508de3ced624ac17fba6da1b637b1697dff..ae806dd578f26fbeac12f880cd7b6031a56aec00 100644
> --- a/fs/fuse/dev_uring_i.h
> +++ b/fs/fuse/dev_uring_i.h
> @@ -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 */
>
> --
> 2.43.0
>
>

Re: [PATCH 2/2] fuse: Flush the io-uring bg queue from fuse_uring_flush_bg

[Joanne Koong]

On Wed, Jul 23, 2025 at 4:51 PM Joanne Koong <joannelkoong@gmail.com> wrote:
>
> On Tue, Jul 22, 2025 at 3:42 PM Bernd Schubert <bschubert@ddn.com> wrote:
> >
> > 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 | 4 ++++
> >  3 files changed, 9 insertions(+)
> >
> > diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> > index 5387e4239d6aa6f7a9780deaf581483cc28a5e68..d5f2fb82c04bf1ee7a35cb1d6d43e639270945af 100644
> > --- a/fs/fuse/dev.c
> > +++ b/fs/fuse/dev.c
> > @@ -2408,6 +2408,8 @@ void fuse_flush_requests(struct fuse_conn *fc, unsigned long timeout)
> >         spin_unlock(&fc->bg_lock);
> >         spin_unlock(&fc->lock);
> >
> > +       fuse_uring_flush_bg(fc);
>
> I think we'll need to get rid of the
> "WARN_ON_ONCE(ring->fc->max_background != UINT_MAX);" in
> fuse_uring_flush_bg() since fuse_flush_requests() sets
> fc->max_background to UINT_MAX a few lines above before making this
> call.
>
Ahh never mind, just realized I read this check in reverse. this looks
fine to me.

Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
>
> Thanks,
> Joanne
>
> > +
> >         /*
> >          * Wait 30s for all the events to complete or abort.  Touch the
> >          * watchdog once per second so that we don't trip the hangcheck timer
> > diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> > index eca457d1005e7ecb9d220d5092d00cf60961afea..acf11eadbf3b6d999b310b5d8a4a6018e83cb2a9 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 55f52508de3ced624ac17fba6da1b637b1697dff..ae806dd578f26fbeac12f880cd7b6031a56aec00 100644
> > --- a/fs/fuse/dev_uring_i.h
> > +++ b/fs/fuse/dev_uring_i.h
> > @@ -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 */
> >
> > --
> > 2.43.0
> >
> >