[PATCH 4/4] block: expose devt for GENHD_FL_HIDDEN disks

Christoph Hellwig
2018-12-06T20:22:00Z

On Thu, Dec 06, 2018@02:48:12PM -0200, Thadeu Lima de Souza Cascardo wrote:
> Without this exposure, lsblk will fail as it tries to find out the
> device's dev_t numbers. This causes a real problem for nvme multipath
> devices, as their slaves are hidden.
>
> Exposing them fixes the problem, even though trying to open the devices
> returns an error in the case of nvme multipath. So, right now, it's the
> driver's responsibility to return a failure to open hidden devices.

So the problem with this is that it will cause udev to actually create
the /dev/nvmeXcYnZ nodes, which due to the previous patch will always
fail to open, which is a bit confusing. I guess we could live with this
if we add udev rules to supress the creation or something, but in general
it is a bit ugly.