- OS allocates block X and fills contents in memory.
- Application fsyncs(). OS writes an entry for updating the metadata to the write-ahead log, as well as writing actual block contents to block X. At this point, the block is committed to disk, so the OS returns from the fsync.
- OS crashes before updating actual metadata. User reboots.
- SSD decides that block X is free (looking at the metadata) and trims it
- OS reboots, applies write-back log. Block X contents have been lost
Or perhaps even:
- OS allocates block X and fills contents in memory. Write activity is low, so writeback is delayed for a while.
- Memory pressure causes block X contents to be flushed to disk. Metadata remains in memory.
- SSD decides block X is unallocated (WAL is empty, block is marked as unallocated) so it frees the block
- OS writes back metadata. Block is now zeroed.
Or even good old fashioned file system corruption being made worse by something like this...
There are specific points in the design docs where they make it clear that they do want to support advanced users installing their own OS, to the extent that that does not cause trouble for less advanced users.
You're angry but you just said you had forgotten about that work for seven years. Was your intention to leave that concept in the graveyard until you died, getting angry should anyone try to profit from it or license it?
If he didn't take a patent on it, then there's nothing stopping IBM from using the same techniques. The problem arises when IBM patents it as if they were the first to invent the technique, then restrict everyone (including the OP) from using the OP's invention. If IBM just used it without patenting, no problem. Of course, it's entirely possible that IBM's invention is slightly different from the OP's - patent claims are rather hard to read for a layman after all.
I thought automated aircraft (no pilot) and RC craft flown by non-pilots were not allowed in controlled airspace in the USA.
Not all US airspace is controlled - in fact, the vast majority is not, particularly at the low altitudes you'd need to be flying at to get this kind of imagery.