Re: [RFC 12/26] ext2 white-out support

From: Jan Blunck
Date: Thu Aug 02 2007 - 08:12:20 EST


On Thu, Aug 02, Ph. Marek wrote:

> On Mittwoch, 1. August 2007, Josef Sipek wrote:
> > Alright not the greatest of examples, there is something to be said about
> > symmetry, so...let me try again :)
> ...
> > Oops! There's a whiteout in /b that hides the directory in /c -- rename(2)
> > shouldn't make directory subtrees disappear.
> >
> > There are two ways to solve this:
> >
> > 1) "cp -r" the entire subtree ...
> >
> > 2) Don't store whiteouts within branches ...
> Sorry for making uninformed guesses, but if there are already special nodes
> (whiteout), why not extending them to some more general format - specifying a
> (source, destination) pair at the topmost level?
> - A delete is a (source, NULL) pair
> - A rename is a (source, destination) pair, which causes lookups on source to
> use the string destination in the lower branches.

Originally I had the idea that whiteouts are a special kind of symlink. After
discussing that with various people sticked to the simplest approach.
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