Re: filesystem transactions API

[John Stoffel]

>>>>> "Jamie" == Jamie Lokier <jamie@xxxxxxxxxxxxx> writes:

Jamie> No.  A transaction means that _all_ processes will see the
Jamie> whole transaction or not.

This is really hard.  How do you handle the case where process X
starts a transaction modifies files a, b & c, but process Y has file b
open for writing, and never lets it go?  Or the file gets unlinked?  

Jamie> For example, you can use transactions for distro package
Jamie> management: a whole update of a package would be a single
Jamie> transaction, so that at no time does any program see an
Jamie> inconsistent set of files.  See why _every_ process in the
Jamie> system must have the same view?

What about programs that are already open and running?  

It might be doable in some sense, but I can see that details are
really hard to get right.  Esp without breaking existing Unix
semantics.  

But then again, I could be smoking something good (or bad :-) here, so
take what I say with a grain of salt.

John
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