[PATCH 17/18] xfs: implement pnfs export operations

[Christoph Hellwig]

On Fri, Jan 09, 2015 at 08:04:05AM +1100, Dave Chinner wrote:
> > If the client sends the opaqueue device ID that contains the generation
> > after the grow to a server that had crashed / restarted the server
> > will reject it as the server starts at zero.  The causes the client
> > to get a new, valid device ID from the server.
> 
> But if the server fs has a generation number of zero when it
> crashes, how does the client tell that it needs a new device ID from
> the server?
>
> > Unlike the NFS file hadles which are persistent the device IDs are volatile
> > handles that can go away (and have really horrible life time rules..).
> 
> Right. How the clients detect that "going away" when the device
> generation is zero both before and after a server crash is the
> question I'm asking....

The server tells the client by rejecting the operation using the
device ID.