Ability to securely erase the free space of SSD's as much as possible

[Removed by request]

I'm using Ubuntu 16.04 dev with secure-delete 3.1-6ubuntu1 and because of the techniques used by SSD's like wear leveling and reserve blocks it is very difficult to reliably delete the remaining free space without deleting the existing data. But secure-delete could try various things (potentially configurable) to lower this issue as much as possible:

- For example it could try to detect the amount of reserve blocks/make a pessimistic assumption/lets the user control the amount and calculate how much write cycles would be needed to go relative sure that all free blocks including reserve blocks are deleted. Possibly filling the complete free space except the last virtual block and repeatedly writing and deleting the last virtual block this way could be effective against dynamic wear leveling.
- Alternatively/additionally dependent on what features the SSD is capable of (like temporary disabling of the wear leveling) they could be used more or less to the advantage.