Re: [Virtio-fs] [PATCH 15/18] virtiofs: Make virtio_fs object refcounted

From: Vivek Goyal
Date: Mon Sep 09 2019 - 11:35:48 EST


On Sun, Sep 08, 2019 at 07:10:03PM +0800, piaojun wrote:
>
>
> On 2019/9/6 3:48, Vivek Goyal wrote:
> > This object is used both by fuse_connection as well virt device. So make
> > this object reference counted and that makes it easy to define life cycle
> > of the object.
> >
> > Now deivce can be removed while filesystem is still mounted. This will
> > cleanup all the virtqueues but virtio_fs object will still be around and
> > will be cleaned when filesystem is unmounted and sb/fc drops its reference.
> >
> > Removing a device also stops all virt queues and any new reuqest gets
> > error -ENOTCONN. All existing in flight requests are drained before
> > ->remove returns.
> >
> > Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> > ---
> > fs/fuse/virtio_fs.c | 52 +++++++++++++++++++++++++++++++++++++--------
> > 1 file changed, 43 insertions(+), 9 deletions(-)
> >
> > diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
> > index 01bbf2c0e144..29ec2f5bbbe2 100644
> > --- a/fs/fuse/virtio_fs.c
> > +++ b/fs/fuse/virtio_fs.c
> > @@ -37,6 +37,7 @@ struct virtio_fs_vq {
> >
> > /* A virtio-fs device instance */
> > struct virtio_fs {
> > + struct kref refcount;
> > struct list_head list; /* on virtio_fs_instances */
> > char *tag;
> > struct virtio_fs_vq *vqs;
> > @@ -63,6 +64,27 @@ static inline struct fuse_pqueue *vq_to_fpq(struct virtqueue *vq)
> > return &vq_to_fsvq(vq)->fud->pq;
> > }
> >
> > +static void release_virtiofs_obj(struct kref *ref)
> > +{
> > + struct virtio_fs *vfs = container_of(ref, struct virtio_fs, refcount);
> > +
> > + kfree(vfs->vqs);
> > + kfree(vfs);
> > +}
> > +
> > +static void virtio_fs_put(struct virtio_fs *fs)
> > +{
> > + mutex_lock(&virtio_fs_mutex);
> > + kref_put(&fs->refcount, release_virtiofs_obj);
> > + mutex_unlock(&virtio_fs_mutex);
> > +}
> > +
> > +static void virtio_fs_put(struct fuse_iqueue *fiq)
> > +{
> > + struct virtio_fs *vfs = fiq->priv;
> > + virtiofs_put(vfs);
> > +}
>
> It's a little confusing that virtiofs_put() looks like virtiofs_put(),
> and could we use __virtio_fs_put to replace virtio_fs_put?

Fixed this in follow up patch I posted.

https://www.redhat.com/archives/virtio-fs/2019-September/msg00091.html

Vivek