Re: filesystem transactions API

[Trond Myklebust]

ty den 26.04.2005 Klokka 11:01 (-0400) skreiv 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?  

That is why implementing it as a form of lock makes sense.

> 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.  

Wrong.

Cheers,
  Trond
-- 
Trond Myklebust <trond.myklebust@xxxxxxxxxx>

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