Re: File as a directory - VFS Changes

[Hans Reiser <reiser@namesys.com>]

Nikita Danilov wrote:

>Alexander G. M. Smith writes:
> > Nikita Danilov wrote on Mon, 30 May 2005 15:00:52 +0400:
> > > Nothing in VFS prevents files from supporting both read(2) and
> > > readdir(3). The problem is with link(2): VFS assumes that directories
> > > form _tree_, that is, every directory has well-defined parent.
> > 
> > At least that's one problem that's solveable.  Just define one of
> > the parents as the master parent directory, with a guaranteed path
> > up to the root, and have the others as auxiliary parents.  That
> > also gives you a good path name to each and every file-thing.
> > 
> > The VFS or the file system (depending on where the designers want
> > to split the work) will still have to handle cycles in the graph
> > to recompute the new master parents, when an old one gets deleted
> > or moved.
>
>Cycle may consists of more graph nodes than fits into memory. 
>
There are pathname length restrictions already in the kernel that should
prevent that, yes?

>Cycle
>detection is crucial for rename semantics, and if
>cycle-just-about-to-be-formed doesn't fit into memory it's not clear how
>to detect it, because tree has to be locked while checked for cycles, and
>one definitely doesn't want to keep such a lock over IO.
>
> > 
> > - Alex
>
>Nikita.
>
>
>  
>