Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx1.redhat.com ([209.132.183.28]:2154 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755906Ab3KLPUl (ORCPT ); Tue, 12 Nov 2013 10:20:41 -0500 Message-ID: <52824784.4080901@RedHat.com> Date: Tue, 12 Nov 2013 10:21:40 -0500 From: Steve Dickson MIME-Version: 1.0 To: Jeff Layton , trond.myklebust@netapp.com CC: linux-nfs@vger.kernel.org Subject: Re: [PATCH 0/2] sunrpc: more reliable detection of running gssd References: <1384261225-28559-1-git-send-email-jlayton@redhat.com> In-Reply-To: <1384261225-28559-1-git-send-email-jlayton@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: On 12/11/13 08:00, 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've just verified that a mount, with these patches, takes about 1.2 seconds when rpc.gssd is not running.... With rpc.gssd it take about .2 seconds. Tested-by: Steve Dickson steved.