Re: [PATCH 00/22][RFC] Unionfs: Stackable Namespace Unification Filesystem

[Al Boldi]

JÃrn Engel wrote:
> On Sun, 3 September 2006 11:05:08 +0000, Pavel Machek wrote:
> > > - Modifying a Unionfs branch directly, while the union is mounted, is
> > >   currently unsupported.  Any such change may cause Unionfs to oops
> > > and it can even result in data loss!
> >
> > I'm not sure if that is acceptable. Even root user should be unable to
> > oops the kernel using 'normal' actions.
>
> Direct modification of branches is similar to direct modification of
> block devices underneith a mounted filesystem.  While I agree that
> such a thing _should_ not oops the kernel, I'd bet that you can easily
> run a stresstest on a filesystem while randomly flipping bits in the
> block device and get just that.

Not really a fair comparison.  The block level is conceptionally totally 
different than the fs level, while a stackable fs is within the realms of 
the fs level.

> There are bigger problems in unionfs to worry about.

Agreed.  Moving basic functionality abstractions into the VFS could easily 
alleviate theses kinds of problems.


Thanks!

--
Al

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