[Stgt-devel] Dealing with filemarks in SSC ...

Richard Sharpe realrichardsharpe
Wed Jul 30 22:22:58 CEST 2008


I have moved closer to properly implementing filemarks (and setmarks)
by thinking through the issues associated with the approach I want to

That is to keep an array of marks (file and set) with offsets into the
backing store file. Whether these are then stored as extended
attributes or as a separate metadata file is an implementation
decision that I am happy with either way.

By the look of things, the cost of detecting a mark on each read op,
at least for fixed block size devices, is a couple of additions and a
comparison in the fast-path (although the code does lots of seeks that
seem unnecessary at the moment as well). I suspect it will amount to
the same for variable block-size devices as well.

Once I have btape tests working correctly I will post a patch for consideration.

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