Re: [RFC PATCH 0/2] Union Mount: Directory listing in glibc

NAGABHUSHAN BS
2008-04-30T06:18:22Z

On Tue, Apr 29, 2008 at 9:34 PM, Jan Blunck <jblunck@suse.de> wrote:
> On Tue, Apr 29, bsn.0007@gmail.com wrote:
>
> > The RFC discussed about the information glibc readdir needs to get about
> > union mounted directories and I have assumed the following information
> > to be available from the kernel for this implementation.
> >
> > - Kernel would return all the dirents (including duplicates and whiteouts)
> > starting from the topmost directory of the union.
> >
> > - Indication that this directory is a union mounted directory
> > I have assumed that kernel would return a "." whiteout as the first
> > directory entry of the union. This would tell glibc readdir(3) that it is
> > working with a union mounted directory and it needs to do duplicate
> > elimination and whiteout suppression. It starts building a dirent cache
> > for this purpose.
>
> IIRC the intention was to emit a "." whiteout when "changing" from one
> directory to the next. That means when the first directory is completely read
> the whiteout is emitted. After that glibc knows to start duplicate
> removal.
>

Yes the intention was to get a "." whiteout when changing from one
directory to next and thats essentially what i have assumed, for
starting duplicate elimination.
Along with that i have also assumed to get a "." whiteout as the first
directory entry of the union, so as to indicate to glibc that the
directory is a union mounted directory.

Regards
Nagabhushan