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Date:   Thu, 8 Nov 2018 08:07:49 -0500
From:   Scott Mayhew <smayhew@redhat.com>
To:     "J. Bruce Fields" <bfields@fieldses.org>
Cc:     jlayton@kernel.org, linux-nfs@vger.kernel.org
Subject: Re: [PATCH RFC 0/4] un-deprecate nfsdcld
Message-ID: <20181108130749.GE7766@coeurl.usersys.redhat.com>
References: <20181106183511.17836-1-smayhew@redhat.com>
 <20181108002855.GA30776@fieldses.org>
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On Wed, 07 Nov 2018, J. Bruce Fields wrote:

> Thanks for doing this, we've really been wanting it.  I should be able
> to get to it in the next few days....
> 
> Out of curiosity, what are you using for testing?

For initially testing the GraceStart upcall, I'd just loaded a bunch of
bogus clientid's into the database and wrote a crash macro to dump out
the reclaim_str_hashtbl to make sure everything got there on startup.

For testing nfsd in a container, right now I'm using plain docker.  I
have one container running nfsd.  I made another image that just runs
cthon against an ip that you pass in via an environment variable.  I
start up a bunch of containers using the cthon image and then
periodically restart the nfsd container.  I'd like to try this stuff
out on OpenShift at some point too.

I'm open to other ideas for testing if you have any.

-Scott
> 
> --b.
> 
> On Tue, Nov 06, 2018 at 01:35:07PM -0500, Scott Mayhew wrote:
> > When nfsdcld was released, it was quickly deprecated in favor of the
> > nfsdcltrack usermodehelper, so as to not require another running daemon.
> > That prevents NFSv4 clients from reclaiming locks from nfsd's running in
> > containers, since neither nfsdcltrack nor the legacy client tracking
> > code work in containers.  These patches un-deprecate the use of nfsdcld
> > for NFSv4 client tracking.
> > 
> > These patches are intended to go alongside some nfs-utils patches that
> > introduce an enhancement that allows nfsd to "slurp" up the client
> > records during client tracking initialization and store them internally
> > in hash table.  This enables nfsd to check whether an NFSv4 client is 
> > allowed to reclaim without having to do an upcall to nfsdcld.  It also
> > allows nfsd to decide to end the v4 grace period early if the number of
> > RECLAIM_COMPLETE operations it has received from "known" clients is
> > equal to the number of entries in the hash table.  It also allows nfsd
> > to skip the v4 grace period altogether if it knows there are no clients
> > allowed to reclaim.
> > 
> > There is a fallback to allow nfsd to continue to work with older nfsdcld
> > daemons in the event that any are out in the wild (unlikely).
> > Everything should work fine except nfsd will not be able to exit the
> > grace period early or skip the grace period altogether.
> > 
> > Scott Mayhew (4):
> >   nfsd: fix a warning in __cld_pipe_upcall()
> >   nfsd: make nfs4_client_reclaim use an xdr_netobj instead of a fixed
> >     char array
> >   nfsd: un-deprecate nfsdcld
> >   nfsd: keep a tally of RECLAIM_COMPLETE operations when using nfsdcld
> > 
> >  fs/nfsd/netns.h               |   3 +
> >  fs/nfsd/nfs4recover.c         | 326 ++++++++++++++++++++++++++++++----
> >  fs/nfsd/nfs4state.c           |  82 +++++++--
> >  fs/nfsd/nfsctl.c              |   1 +
> >  fs/nfsd/state.h               |   8 +-
> >  include/uapi/linux/nfsd/cld.h |   1 +
> >  6 files changed, 372 insertions(+), 49 deletions(-)
> > 
> > -- 
> > 2.17.1