[Users] Snapshot merging and the effect on underlying LV metadata

[Alasdair G Kergon]

In lvm2 version 2.02.105 lvconvert gained a --splitsnapshot option to
allow people to wipe snapshot content before releasing the extents
for reallocation.

       --splitsnapshot
              Separates SnapshotLogicalVolume from  its  origin.   The  volume
              that  is split off contains the chunks that differ from the ori-
              gin along with the metadata describing them.  This volume can be
              wiped  and then destroyed with lvremove.  The inverse of --snap-
              shot.

Alasdair