On Thu, Oct 05, 2023 at 04:30:30PM -0400, Vivek Goyal wrote: > virtiofs filesystem is mounted using a "tag" which is exported by the > virtiofs device. virtiofs driver knows about all the available tags but > these are not exported to user space. > > People have asked these tags to be exported to user space. Most recently > Lennart Poettering has asked for it as he wants to scan the tags and mount > virtiofs automatically in certain cases. > > https://gitlab.com/virtio-fs/virtiofsd/-/issues/128 > > This patch exports tags through sysfs. One tag is associated with each > virtiofs device. A new "tag" file appears under virtiofs device dir. > Actual filesystem tag can be obtained by reading this "tag" file. > > For example, if a virtiofs device exports tag "myfs", a new file "tag" > will show up here. > > /sys/bus/virtio/devices/virtio<N>/tag > > # cat /sys/bus/virtio/devices/virtio<N>/tag > myfs > > Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx> > --- > fs/fuse/virtio_fs.c | 34 ++++++++++++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > > diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c > index 5f1be1da92ce..a5b11e18f331 100644 > --- a/fs/fuse/virtio_fs.c > +++ b/fs/fuse/virtio_fs.c > @@ -107,6 +107,21 @@ static const struct fs_parameter_spec virtio_fs_parameters[] = { > {} > }; > > +/* Forward Declarations */ > +static void virtio_fs_stop_all_queues(struct virtio_fs *fs); > + > +/* sysfs related */ > +static ssize_t tag_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct virtio_device *vdev = container_of(dev, struct virtio_device, > + dev); > + struct virtio_fs *fs = vdev->priv; > + > + return sysfs_emit(buf, "%s", fs->tag); > +} > +static DEVICE_ATTR_RO(tag); > + > static int virtio_fs_parse_param(struct fs_context *fsc, > struct fs_parameter *param) > { > @@ -265,6 +280,15 @@ static int virtio_fs_add_instance(struct virtio_fs *fs) > return 0; > } > > +static void virtio_fs_remove_instance(struct virtio_fs *fs) > +{ > + mutex_lock(&virtio_fs_mutex); > + list_del_init(&fs->list); > + virtio_fs_stop_all_queues(fs); > + virtio_fs_drain_all_queues_locked(fs); > + mutex_unlock(&virtio_fs_mutex); > +} > + > /* Return the virtio_fs with a given tag, or NULL */ > static struct virtio_fs *virtio_fs_find_instance(const char *tag) > { > @@ -891,8 +915,15 @@ static int virtio_fs_probe(struct virtio_device *vdev) > if (ret < 0) > goto out_vqs; > > + /* Export tag through sysfs */ > + ret = device_create_file(&vdev->dev, &dev_attr_tag); > + if (ret < 0) > + goto out_sysfs_attr; You just raced with userspace and lost :( Please use default groups for your device/bus, that is what they are there for. thanks, greg k-h
