Implement automatic online expansion of GELI providers - if the underlying

Implement automatic online expansion of GELI providers - if the underlying
provider grows, GELI will expand automatically and will move the metadata
to the new location of the last sector.

This functionality is turned on by default. It can be turned off with the
-R flag, but it is not recommended - if the underlying provider grows and
automatic expansion is turned off, it won't be possible to attach this
provider again, as the metadata is no longer located in the last sector.

If the automatic expansion is turned off and the underlying provider grows,
GELI will only log a message with the previous size of the provider, so
recovery can be easier.

Obtained from:	Fudo Security