[openbeosstorage] Re: BDiskSystem::Supports*()/Validate*()

> [...]
> > > Thus in principle also Move() should have something like a `bool
> > > force'
> > > parameter; or maybe `uint32 options' where options can be
> > > B_MOVE_PARTITION_ALL, B_MOVE_PARTITION_FORCE,
> > > B_MOVE_PARTITION_IGNORE_CONTENTS.
> > 
> > Does B_MOVE_PARITION_ALL succeed iff you can move all partitions?
> 
> Yep.
> 
> > And
> > is FORCE then "move as many as you can, destroying those that say
> > they
> > can't be moved"
> 
> All partitions claiming, that they can be moved in principle, are 
> tried
> to be moved. If moving any of them fails, the complete Move() reports
> an error. So it's `move all partitions whose disk systems reported 
> them
> as movable'. Since the respective syscall for Move() will internally 
> do
> the equivalent of a ValidateMove() first, the shadow partitions won't
> be touched, if it fails.

Sounds okay.

> > and IGNORE "just move it and wipe out the contents"?
> 
> That would have the same semantics as deleting the partition and re-
> creating it at the new position. Alternatively the partition could be
> moved indeed, which would save all descendants, that don't use 
> absolute
> addressing. I changed the KDiskSystem::SupportsMoving() parameter from
> `whileMounted' to `isNoOp', which is equivalent in case of file
> systems, but gives more info for partitioning systems. So, all
> descendants for which moving is a no-op would survive. Don't know, if
> that is desired though -- one would probably use FORCE in this case
> anyway.
> 
> I'm not even sure, that IGNORE would be used in practice. How I
> imagined DriveSetup to work when the user moves a partition, would be
> to do a ValidateMove() to find out whether descendant partitions are
> movable or not, ask the user something like `Partitions X, Y, Z are 
> not
> movable. Their data will be destroyed, when proceeding. [Nuke Them]
> [[Cancel]]'. So, FORCE would be used, otherwise (if all descendants 
> are
> movable) ALL. Hence I only added a `bool force' parameter. But I can
> change that, if you think, that other variant is better.

No, I think having the bool is fine. I agree, I don't really think 
IGNORE would be used in general.

> > > Finally there's BPartition::ValidateMove(), which is a bit tricky.
> > > I
> > > think, it would be quite difficult to try to negotiate a value 
> > > that
> > > all
> > > affected disk systems are happy with. So I would only try to fine 
> > > a
> > > value acceptable for the partitioning system responsible for the
> > > partition in question and its contained disk system, and fail 
> > > after
> > > one
> > > or two unsuccessful iterations. For the descendants I would only
> > > ask,
> > > if they are OK with the new value and just fail, if any of them is
> > > not.
> > 
> > Sounds fair. We could always try something more thorough if we ever
> > find ourselves with lots of free time on our hands. :-)
> 
> Hehe, if that will ever happen... ;-)

Any day now... :-)

-Tyler

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