[linux-lvm] unable to exclude LVs using global_filter

[Alasdair G Kergon]

The key concept to grasp is that LVM works with devices (i.e. major
number + minor number pairs) rather than filesystem paths and it makes a
single "use or ignore" decision for each device (not for each path).

One device might be reachable through more than one filesystem path that
lvm has been configured to check and, if so, all the paths are checked
against the filter independently and the results feed into that single
decision according to the rules described.

Alasdair