Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx1.redhat.com ([209.132.183.28]:28939 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753656Ab3KLQIe (ORCPT ); Tue, 12 Nov 2013 11:08:34 -0500 Date: Tue, 12 Nov 2013 11:08:31 -0500 From: Jeff Layton To: Chuck Lever Cc: trond.myklebust@netapp.com, linux-nfs@vger.kernel.org, steved@redhat.com Subject: Re: [PATCH 0/2] sunrpc: more reliable detection of running gssd Message-ID: <20131112110831.72234c64@tlielax.poochiereds.net> In-Reply-To: References: <1384261225-28559-1-git-send-email-jlayton@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, 12 Nov 2013 11:02:42 -0500 Chuck Lever wrote: > > On Nov 12, 2013, at 8:00 AM, Jeff Layton wrote: > > > We've gotten a lot of complaints recently about the 15s delay when > > doing a sec=sys mount without gssd running. > > > > A large part of the problem is that the kernel isn't able to reliably > > detect when rpc.gssd is running. What we currently have is a > > gssd_running flag that is initially set to 1. When an upcall times out, > > that gets set to 0, and subsequent upcalls get a much shorter timeout > > (1/4s instead of 15s). It's reset back to '1' when a pipe is reopened. > > > > The approach of using a flag like this is pretty inadequate. First, it > > doesn't eliminate the long delay on the initial upcall attempt. Also, > > if gssd spontaneously dies, then the flag will still be set to 1 until > > the next upcall attempt times out. Finally, it currently requires that > > the pipe be reopened in order to reset the flag back to true. > > > > This patchset replaces that flag with a more reliable mechanism for > > detecting when gssd is running. When rpc_pipefs is mounted, it creates a > > new "dummy" pipe that gssd will naturally find and hold open. We'll > > never send an upcall down this pipe, and writing to it always fails. > > But, since we can detect when something is holding it open, we can use > > that to determine whether gssd is running. > > > > The current patch just uses this mechanism to replace the gssd_running > > flag with this new mechanism. This shortens the long delay when mounting > > without gssd running, but does not silence these warnings: > > > > RPC: AUTH_GSS upcall timed out. > > Please check user daemon is running. > > > > I'm willing to add a patch to do that, but I'm a little unclear on the > > best way to do so. Those messages are generated by the auth_gss code. We > > probably do want to print them if someone mounted with sec=krb5, but > > suppress them when mounting with sec=sys. > > > > Do we need to somehow pass down that intent to auth_gss? Another idea > > would be to call gssd_running() from the nfs mount code and use that to > > determine whether to try and use krb5 at all... > > > > Discuss! > > I'd like to pursue the module loading solution as well. > Sorry, I missed that part of the discussion. What's the module loading solution? -- Jeff Layton