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Date:   Fri, 6 Sep 2019 13:03:09 +0100
From:   Stefan Hajnoczi <stefanha@redhat.com>
To:     Vivek Goyal <vgoyal@redhat.com>
Cc:     linux-fsdevel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, miklos@szeredi.hu,
        linux-kernel@vger.kernel.org, virtio-fs@redhat.com,
        dgilbert@redhat.com, mst@redhat.com
Subject: Re: [PATCH 15/18] virtiofs: Make virtio_fs object refcounted
Message-ID: <20190906120309.GW5900@stefanha-x1.localdomain>
References: <20190905194859.16219-1-vgoyal@redhat.com>
 <20190905194859.16219-16-vgoyal@redhat.com>
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On Thu, Sep 05, 2019 at 03:48:56PM -0400, 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.
>=20
> 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 referenc=
e.
>=20
> 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.
>=20
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
>  fs/fuse/virtio_fs.c | 52 +++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 43 insertions(+), 9 deletions(-)
>=20
> 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 {
> =20
>  /* 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 vir=
tqueue *vq)
>  	return &vq_to_fsvq(vq)->fud->pq;
>  }
> =20
> +static void release_virtiofs_obj(struct kref *ref)
> +{
> +	struct virtio_fs *vfs =3D container_of(ref, struct virtio_fs, refcount);
> +
> +	kfree(vfs->vqs);
> +	kfree(vfs);
> +}
> +
> +static void virtiofs_put(struct virtio_fs *fs)

Why do the two function names above contain "virtiofs" instead
of "virtio_fs"?  I'm not sure if this is intentional and is supposed to
mean something, but it's confusing.

> +{
> +	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)

Minor issue: this function name is confusingly similar to
virtiofs_put().  Please rename to virtio_fs_fiq_put().

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