[systemd-devel] udev and btrfs multiple devices

[Greg KH]

On Thu, Jan 28, 2021 at 01:32:03AM -0700, Chris Murphy wrote:
> On Thu, Jan 28, 2021 at 1:03 AM Greg KH <gregkh at linuxfoundation.org> wrote:
> >
> > On Wed, Jan 27, 2021 at 05:19:38PM -0700, Chris Murphy wrote:
> > >
> > > Next, is it possible to enhance udev so that it can report the number
> > > of devices expected for a Btrfs file system? This information is
> > > currently in the Btrfs superblock found on each device in the
> > > num_devices field.
> > > https://github.com/storaged-project/udisks/pull/838#issuecomment-768372627
> >
> > It's not up to udev to report that, but rather have either the kernel
> > export that, or have the tool that udev calls determine that.
> 
> I mean expose in udevadm info, e.g.
> 
> E: ID_BTRFS_NUM_DEVICES=4

Again, that is up to either the kernel, or a tool that udev calls to do
that, udev itself doesn't know device-specific things, that's not what
it is designed to do.

thanks,

greg k-h