Re: silent semantic changes with reiser4

[Christoph Hellwig]

On Thu, Aug 26, 2004 at 05:19:11PM +0100, Jamie Lokier wrote:
> Remember that reiser4 allows you to operate on little pieces of data,
> glueing and rearranging them inside files (something like that).
> 
> No other filesystem has that capability, and it's a data model which
> the fancy features (when they exist) will use.
> 
> You can map those pieces to underlying directories and files and
> renames and unlinks, so that the fancy stuff works on other
> filesystems, but it would be a useless model because those other
> filesystems wouldn't be recognisably "ordinary" files any more.
> 
> For reiser4 to expose that model through a VFS interface, and the
> fancy stuff to use it through the VFS interface, and for the fancy
> stuff to work (even imperfectly) on other filesystems which don't
> offer those operations, some kind of fall-back "store metadata and
> fragment rearrangements in auxiliary files with special names" layer
> would be requied.  That's a big job.

I seem to miss those files in the current implementation.  But again the
big question is how will the interface look?  If the smaller objects
interact with normal files (link/rename, contained in normal
directories), they will have to obey the same locking protocols.  If not
a filesystem could experiment with it of course.

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