Re: [RFC][PATCH 5/8] add f_op for checkpointability

[Dave Hansen <dave@linux.vnet.ibm.com>]

On Tue, 2009-03-03 at 08:15 -0500, Christoph Hellwig wrote:
> On Mon, Mar 02, 2009 at 09:05:56AM -0800, Dave Hansen wrote:
> > On Sat, 2009-02-28 at 15:53 -0500, Christoph Hellwig wrote:
> > > Also the double-use of the op seem not very nice to me.  Is there any
> > > real life use case were you would have the operation on a file but
> > > sometimes not allow checkpoiting?
> > 
> > I'm still reaching here...
> > 
> > I was thinking of /proc.  Opening your own /proc/$$/* would certainly be
> > considered OK.  But, doing it for some other process not in your pid
> > namespace would not be OK and would not be checkpointable.
> > 
> > I know we're not quite in real-life territory here, yet, but I'm still
> > thinking.
> 
> That mighr be a good enough excuse, I was just wondering what the use
> case was.

I just thought of another one: unlinked files and directories.  They're
a pain to checkpoint and won't be supported for a while.  Holding open
an unlinked file would make a process uncheckpointable for a bit.

-- Dave