Commit c17ea009 authored by Vivek Goyal's avatar Vivek Goyal Committed by Miklos Szeredi
Browse files

virtiofs: Count pending forgets as in_flight forgets 



If virtqueue is full, we put forget requests on a list and these forgets
are dispatched later using a worker. As of now we don't count these forgets
in fsvq->in_flight variable. This means when queue is being drained, we
have to have special logic to first drain these pending requests and then
wait for fsvq->in_flight to go to zero.

By counting pending forgets in fsvq->in_flight, we can get rid of special
logic and just wait for in_flight to go to zero. Worker thread will kick
and drain all the forgets anyway, leading in_flight to zero.

I also need similar logic for normal request queue in next patch where I am
about to defer request submission in the worker context if queue is full.

This simplifies the code a bit.

Also add two helper functions to inc/dec in_flight. Decrement in_flight
helper will later used to call completion when in_flight reaches zero.

Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 5dbe190f

fs/fuse/virtio_fs.c

+20 −24
Original line number Diff line number Diff line
@@ -67,6 +67,19 @@ static inline struct fuse_pqueue *vq_to_fpq(struct virtqueue *vq) 
	return &vq_to_fsvq(vq)->fud->pq;

}



/* Should be called with fsvq->lock held. */

static inline void inc_in_flight_req(struct virtio_fs_vq *fsvq)

{

	fsvq->in_flight++;

}



/* Should be called with fsvq->lock held. */

static inline void dec_in_flight_req(struct virtio_fs_vq *fsvq)

{

	WARN_ON(fsvq->in_flight <= 0);

	fsvq->in_flight--;

}



static void release_virtio_fs_obj(struct kref *ref)

{

	struct virtio_fs *vfs = container_of(ref, struct virtio_fs, refcount);
@@ -110,22 +123,6 @@ static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq) 
	flush_delayed_work(&fsvq->dispatch_work);

}



static inline void drain_hiprio_queued_reqs(struct virtio_fs_vq *fsvq)

{

	struct virtio_fs_forget *forget;



	spin_lock(&fsvq->lock);

	while (1) {

		forget = list_first_entry_or_null(&fsvq->queued_reqs,

						struct virtio_fs_forget, list);

		if (!forget)

			break;

		list_del(&forget->list);

		kfree(forget);

	}

	spin_unlock(&fsvq->lock);

}



static void virtio_fs_drain_all_queues(struct virtio_fs *fs)

{

	struct virtio_fs_vq *fsvq;
@@ -133,9 +130,6 @@ static void virtio_fs_drain_all_queues(struct virtio_fs *fs) 


	for (i = 0; i < fs->nvqs; i++) {

		fsvq = &fs->vqs[i];

		if (i == VQ_HIPRIO)

			drain_hiprio_queued_reqs(fsvq);



		virtio_fs_drain_queue(fsvq);

	}

}
@@ -254,7 +248,7 @@ static void virtio_fs_hiprio_done_work(struct work_struct *work) 


		while ((req = virtqueue_get_buf(vq, &len)) != NULL) {

			kfree(req);

			fsvq->in_flight--;

			dec_in_flight_req(fsvq);

		}

	} while (!virtqueue_enable_cb(vq) && likely(!virtqueue_is_broken(vq)));

	spin_unlock(&fsvq->lock);
@@ -306,6 +300,7 @@ static void virtio_fs_hiprio_dispatch_work(struct work_struct *work) 


		list_del(&forget->list);

		if (!fsvq->connected) {

			dec_in_flight_req(fsvq);

			spin_unlock(&fsvq->lock);

			kfree(forget);

			continue;
@@ -327,13 +322,13 @@ static void virtio_fs_hiprio_dispatch_work(struct work_struct *work) 
			} else {

				pr_debug("virtio-fs: Could not queue FORGET: err=%d. Dropping it.\n",

					 ret);

				dec_in_flight_req(fsvq);

				kfree(forget);

			}

			spin_unlock(&fsvq->lock);

			return;

		}



		fsvq->in_flight++;

		notify = virtqueue_kick_prepare(vq);

		spin_unlock(&fsvq->lock);
@@ -472,7 +467,7 @@ static void virtio_fs_requests_done_work(struct work_struct *work) 


		fuse_request_end(fc, req);

		spin_lock(&fsvq->lock);

		fsvq->in_flight--;

		dec_in_flight_req(fsvq);

		spin_unlock(&fsvq->lock);

	}

}
@@ -730,6 +725,7 @@ __releases(fiq->lock) 
			list_add_tail(&forget->list, &fsvq->queued_reqs);

			schedule_delayed_work(&fsvq->dispatch_work,

					msecs_to_jiffies(1));

			inc_in_flight_req(fsvq);

		} else {

			pr_debug("virtio-fs: Could not queue FORGET: err=%d. Dropping it.\n",

				 ret);
@@ -739,7 +735,7 @@ __releases(fiq->lock) 
		goto out;

	}



	fsvq->in_flight++;

	inc_in_flight_req(fsvq);

	notify = virtqueue_kick_prepare(vq);



	spin_unlock(&fsvq->lock);
@@ -921,7 +917,7 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq, 
	/* matches barrier in request_wait_answer() */

	smp_mb__after_atomic();



	fsvq->in_flight++;

	inc_in_flight_req(fsvq);

	notify = virtqueue_kick_prepare(vq);



	spin_unlock(&fsvq->lock);