> + device->open_count++;
> + if (device->open_count == 1 && device->ops->open_device) {
I would have written this as
if (++device->open_count == 1 && device->ops->open_device) {
to make the pattern more clear, but that is just a minor nitpick.
Otherwise looks good:
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
