Re: panic on 4.20 server exporting xfs filesystem

["J. Bruce Fields" <bfields@fieldses.org>]

On Sun, Mar 08, 2015 at 04:30:56PM +0100, Christoph Hellwig wrote:
> On Thu, Mar 05, 2015 at 03:47:49PM -0500, J. Bruce Fields wrote:
> > nfsd: client 192.168.122.32 failed to respond to layout recall.   Fencing..
> > nfsd: fence failed for client 192.168.122.32: -2!
> > nfsd: client 192.168.122.32 failed to respond to layout recall.   Fencing..
> > nfsd: fence failed for client 192.168.122.32: -2!
> 
> There is no userspace elper to do the fencing, so unfortunately this
> is expecvted.
> 
> > receive_cb_reply: Got unrecognized reply: calldir 0x1 xpt_bc_xprt ffff88005639a000 xid c21abd62
> 
> Now this looks like some issue with the low-level callback path.  I've never
> seen tis before, but from looking at receive_cb_reply this happens if
> xprt_lookup_rqst can't find a rpc_rqst structured for the xid.  Looks like
> we might be corrupting the request list / xid allocation somewhere?
> 
> I can prepare a patch for you to aid with xid tracing if you want.

I'll take a look when I get back.  But before that I'd like to
understand why the layout seems to be left here blocking writes forever,
instead of getting cleaned up after a lease period with no layout
return.

--b.