Re: [RFC 11/26] tmpfs white-out support

[Matt Mackall <mpm@selenic.com>]

On Wed, Aug 01, 2007 at 04:13:46PM +0100, Hugh Dickins wrote:
> On Mon, 30 Jul 2007, Jan Blunck wrote:
> 
> > Introduce white-out support to tmpfs.
> > 
> > Signed-off-by: Jan Blunck <jblunck@suse.de>
> > ---
> >  include/linux/shmem_fs.h |    1 
> >  mm/shmem.c               |   54 +++++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 55 insertions(+)
> 
> I see there's debate about whether this (and its fellows) give the
> right semantic to whiteouts; and I've not begun to think about that.
> 
> But as a patch to tmpfs for what you're trying to do, it looks just
> about fine.  I say "just about" because the reference counting looks
> right, but I wouldn't dare say that it _is_ right without testing.
> 
> And I'd probably want to add a minor adjustment, so that a mount with
> nr_inodes=1000 could still support exactly 1000 inodes, despite your
> allocating one for the whiteout (usually never used) at mount time.
> But that can follow along later, no problem.

Also, you might want to make sure whiteouts work with ramfs, which
replaces tmpfs when tmpfs is disabled.

-- 
Mathematics is the supreme nostalgia of our time.