Use internal LVs (if any) to calculate space used by existing LVs
Use internal LVs (if any) to calculate space used by existing LVs

This is more precise than our artificial numbers and algorithms.

AdamWill/blivet,AdamWill/blivet,vojtechtrefny/blivet,jkonecny12/blivet,rvykydal/blivet,rhinstaller/blivet,jkonecny12/blivet,vojtechtrefny/blivet,rvykydal/blivet,rhinstaller/blivet