linux-kernel - Re: [Virtio-fs] [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time

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Date:   Sun, 8 Sep 2019 18:11:13 +0800
From:   piaojun <piaojun@...wei.com>
To:     Vivek Goyal <vgoyal@...hat.com>, <linux-fsdevel@...r.kernel.org>,
        <virtualization@...ts.linux-foundation.org>, <miklos@...redi.hu>
CC:     <mst@...hat.com>, <linux-kernel@...r.kernel.org>,
        <virtio-fs@...hat.com>
Subject: Re: [Virtio-fs] [PATCH 08/18] virtiofs: Drain all pending requests
 during ->remove time



On 2019/9/6 3:48, Vivek Goyal wrote:
> When device is going away, drain all pending requests.
> 
> Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
> ---
>  fs/fuse/virtio_fs.c | 83 ++++++++++++++++++++++++++++-----------------
>  1 file changed, 51 insertions(+), 32 deletions(-)
> 
> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
> index 90e7b2f345e5..d5730a50b303 100644
> --- a/fs/fuse/virtio_fs.c
> +++ b/fs/fuse/virtio_fs.c
> @@ -63,6 +63,55 @@ static inline struct fuse_pqueue *vq_to_fpq(struct virtqueue *vq)
>  	return &vq_to_fsvq(vq)->fud->pq;
>  }
>  
> +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
> +{
> +	WARN_ON(fsvq->in_flight < 0);
> +
> +	/* Wait for in flight requests to finish.*/

blank space missed after *finish.*.

> +	while (1) {
> +		spin_lock(&fsvq->lock);
> +		if (!fsvq->in_flight) {
> +			spin_unlock(&fsvq->lock);
> +			break;
> +		}
> +		spin_unlock(&fsvq->lock);
> +		usleep_range(1000, 2000);
> +	}
> +
> +	flush_work(&fsvq->done_work);
> +	flush_delayed_work(&fsvq->dispatch_work);
> +}
> +
> +static inline void drain_hiprio_queued_reqs(struct virtio_fs_vq *fsvq)

Should we add *virtio_fs* prefix for this function? And I wonder if
there are only forget reqs to drain? Maybe we should call it
*virtio_fs_drain_queued_forget_reqs* or someone containing *forget_reqs*.

Thanks,
Jun

> +{
> +	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;
> +	int i;
> +
> +	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);
> +	}
> +}
> +
>  /* Add a new instance to the list or return -EEXIST if tag name exists*/
>  static int virtio_fs_add_instance(struct virtio_fs *fs)
>  {
> @@ -511,6 +560,7 @@ static void virtio_fs_remove(struct virtio_device *vdev)
>  	struct virtio_fs *fs = vdev->priv;
>  
>  	virtio_fs_stop_all_queues(fs);
> +	virtio_fs_drain_all_queues(fs);
>  	vdev->config->reset(vdev);
>  	virtio_fs_cleanup_vqs(vdev, fs);
>  
> @@ -865,37 +915,6 @@ __releases(fiq->waitq.lock)
>  	}
>  }
>  
> -static void virtio_fs_flush_hiprio_queue(struct virtio_fs_vq *fsvq)
> -{
> -	struct virtio_fs_forget *forget;
> -
> -	WARN_ON(fsvq->in_flight < 0);
> -
> -	/* Go through pending forget requests and free them */
> -	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);
> -
> -	/* Wait for in flight requests to finish.*/
> -	while (1) {
> -		spin_lock(&fsvq->lock);
> -		if (!fsvq->in_flight) {
> -			spin_unlock(&fsvq->lock);
> -			break;
> -		}
> -		spin_unlock(&fsvq->lock);
> -		usleep_range(1000, 2000);
> -	}
> -}
> -
>  const static struct fuse_iqueue_ops virtio_fs_fiq_ops = {
>  	.wake_forget_and_unlock		= virtio_fs_wake_forget_and_unlock,
>  	.wake_interrupt_and_unlock	= virtio_fs_wake_interrupt_and_unlock,
> @@ -988,7 +1007,7 @@ static void virtio_kill_sb(struct super_block *sb)
>  	spin_lock(&fsvq->lock);
>  	fsvq->connected = false;
>  	spin_unlock(&fsvq->lock);
> -	virtio_fs_flush_hiprio_queue(fsvq);
> +	virtio_fs_drain_all_queues(vfs);
>  
>  	fuse_kill_sb_anon(sb);
>  	virtio_fs_free_devs(vfs);
>