Ts'o: Delayed allocation and the zero-length file problem

Ts'o: Delayed allocation and the zero-length file problem

Posted Mar 20, 2009 13:48 UTC (Fri) by anton (guest, #25547)
In reply to: Ts'o: Delayed allocation and the zero-length file problem by Nick
Parent article: Ts'o: Delayed allocation and the zero-length file problem

[...] it is not like a C compiler that adds some new crazy optimisation that can break any threaded program that previously was working (like speculatively writing to a variable that is never touched in logical control flow)

That's actually a very good example: ext4 performs the writes in a different order than what corresponds to the operations in the process(es), resulting in an on-disk state that never was the logical state of the file system at any point in time. One difference is that file systems have been crash-vulnerable ("crazy") for a long time, so in a variation of the Stockholm syndrome a number of people now insist that that's the right thing.

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