Re: [PATCH 19/39] union-mount: Implement union lookup

From: Valerie Aurora
Date: Tue Aug 17 2010 - 17:44:32 EST


On Fri, Aug 13, 2010 at 03:49:04PM +0200, Miklos Szeredi wrote:
> On Sun, 8 Aug 2010, Valerie Aurora wrote:
> > Implement unioned directories, whiteouts, and fallthrus in pathname
> > lookup routines. do_lookup() and lookup_hash() call lookup_union()
> > after looking up the dentry from the top-level file system.
> > lookup_union() is centered around __lookup_hash(), which does cached
> > and/or real lookups and revalidates each dentry in the union stack.
> >
> > XXX - implement negative union cache entries
> >
> > XXX - handle different permissions on directories
>
> If process doing the lookup doesn't have write permission on the top
> level directory then the lookup will fail. This is not intended, is
> it?

Does it fail? I'm not checking permissions before calling
->fallthru(). But I can't test this because the code doesn't set the
owner of the copied up directory correctly. :)

Don't bother doing any permission testing on this version - it's known
buggy and I will fix it in the next release.

Thanks,

-VAL
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