Re: reiser4 (was Re: [PATCH] Revised extended attributesinterface)

[Hans Reiser <reiser@xxxxxxxxxxx>]

curtis@xxxxxxxxxxxxxx wrote:

> Hans Reiser wrote:
>
> > What I am saying is that each of the N permutations required to
> > transform a file into an extended attribute should be separately
> > selectable.  Theory guys would call this orthogonalizing the primitives.
> > (I am a theory guy.;-) ).
>
> Applying such rigor in the architecture design phase is probably a good
> idea.  Doing it at application run time is not so clear to me.
>
> If you think of files and EAs as apples and oranges, knowing the minimal
> set of orthogonal steps to turn an apple into an orange is good when
> designing, but I hesitate to burden an app with having to select the
> "skin-color" characteristic separately from the "ascorbic acid content"
> characteristic.  IMHO, files and EAs are "package deals" where we have
> chosen a different set of characteristics for each, ones that we believe
> will be useful to an app.
>
> At bottom, a file holds an uninterpreted data stream.  You have to ask
> yourself whether you want that to change or not.  If not, then you
> build any additional functionality in selectable layers on top of the
> filesystem, not in it.  If you do want it to change, then you are
> headed down the path of pulling a database into the filesystem.  Come
> to think of it, I believe that someone is already doing that.  :-)
>
>
> Having an interface such that an app can ask for
>         open("pizza-pie", F_OLIVES|F_PEPPERONI|F_ANCHOVIES|F_PINEAPPLE...)
> where each of the "F_*" options are orthogonal and ask the filesystem to
> layer in a different "filter" between the raw data and the app, or to
> change the access characteristics (eg: block alignment, non-buffered,
> etc), sounds overly complex.  I believe that this would be better done
> by explicitly stacking filesystems in a per-process namespace.

#define PIZZA F_OLIVES|F_PEPPERONI|F_ANCHOVIES|F_PINEAPPLE

#define EDIBLE_PIZZA F_OLIVES|F_PEPPERONI|F_PINEAPPLE

Your way allows for PIZZA but not EDIBLE_PIZZA to be selected by users. 
Both
are easy to specify.  

You cannot know in advance what a user will consider to be EDIBLE_PIZZA. 
Not allowing choice is for, umh, better I not say what OS likes to 
prevent choice......;-)

Ok, so I understand that what I am advocating is a lot of work, and a 
much harder path to take,
and I understand why you feel you have enough work, and I think we can 
both respect each
other for our positions.

I'll try to convince you again when I have working code that isn't 
monstrous code, but allows
users full choice, ok?

Best,

Hans