drive is known to the configuration check also if it already has a geom.
Without this check several needless geoms are created and valid
configuration data was overwritten.
This change obsoletes the need for a separate geom to taste an
offered provider and the consumer doesn't need to be opened with the
exclusive bit set.
vinumdrive geom with an exclusive bit. This should fix the problem
when underlying partitions overlap (i.e. the 'a' partition is at
the same offset as the 'c' partition).
Ideas borrowed from pjd@, quite a bit of testing by
Matthias Schuendehuette <msch@snafu.de>.
not active GEOM providers, it will result in a kernel panic.
If the GEOM provider or disk goes away before the volume
configuration data gets written to the disk, it will result
in another kernel panic.
o Make sure that the drives specified for volume creation
are active GEOM providers.
o When writing out volume configuration data to associated drives,
make sure that the GEOM provider is active, otherwise continue
to the next drive in the volume.
Approved by: le, bmilekic (mentor)
allocated ressouces should be ultimately freed in gv_destroy_geom()
(when unloading the module and not earlier), but I need to look at this
more closely.
