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worst-case atomic operations:
-----------------------------
unlinking a file:
changes:
unallocating all blocks associated.
unallocating inode associated.
dir data change
dir inode change
12k/meg lost
start_atomic
date-stamp chagnes?
changes list?
end_atomic
segment header contains "atomic" bit.
"last" changes thrown out if next segment unreadable.
queue up changes based on last "event" version recorded
block descriptor:
parent | inode or block list? | event #
----------------------------------------
32bit 1 bit 15bit
== 10 bytes
1012k/segment