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From:   Olga Kornievskaia <olga.kornievskaia@gmail.com>
Date:   Tue, 8 Jun 2021 16:56:39 -0400
Message-ID: <CAN-5tyFYyxYr4joR6uPR7zoFToYMmntNdkUkNWV=g33OVXFuOw@mail.gmail.com>
Subject: Re: [PATCH 1/1] NFSv4.1+ add trunking when server trunking detected
To:     Chuck Lever III <chuck.lever@oracle.com>
Cc:     Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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On Tue, Jun 8, 2021 at 4:41 PM Chuck Lever III <chuck.lever@oracle.com> wrote:
>
>
>
> > On Jun 8, 2021, at 2:45 PM, Olga Kornievskaia <olga.kornievskaia@gmail.com> wrote:
> >
> > From: Olga Kornievskaia <kolga@netapp.com>
> >
> > After trunking is discovered in nfs4_discover_server_trunking(),
> > add the transport to the old client structure before destroying
> > the new client structure (along with its transport).
> >
> > Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > ---
> > fs/nfs/nfs4client.c | 40 ++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 40 insertions(+)
> >
> > diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
> > index 42719384e25f..984c851844d8 100644
> > --- a/fs/nfs/nfs4client.c
> > +++ b/fs/nfs/nfs4client.c
> > @@ -361,6 +361,44 @@ static int nfs4_init_client_minor_version(struct nfs_client *clp)
> >       return nfs4_init_callback(clp);
> > }
> >
> > +static void nfs4_add_trunk(struct nfs_client *clp, struct nfs_client *old)
> > +{
> > +     struct sockaddr_storage clp_addr, old_addr;
> > +     struct sockaddr *clp_sap = (struct sockaddr *)&clp_addr;
> > +     struct sockaddr *old_sap = (struct sockaddr *)&old_addr;
> > +     size_t clp_salen, old_salen;
> > +     struct xprt_create xprt_args = {
> > +             .ident = old->cl_proto,
> > +             .net = old->cl_net,
> > +             .servername = old->cl_hostname,
> > +     };
> > +     struct nfs4_add_xprt_data xprtdata = {
> > +             .clp = old,
> > +     };
> > +     struct rpc_add_xprt_test rpcdata = {
> > +             .add_xprt_test = old->cl_mvops->session_trunk,
> > +             .data = &xprtdata,
> > +     };
> > +
> > +     if (clp->cl_proto != old->cl_proto)
> > +             return;
> > +     clp_salen = rpc_peeraddr(clp->cl_rpcclient, clp_sap, sizeof(clp_addr));
> > +     old_salen = rpc_peeraddr(old->cl_rpcclient, old_sap, sizeof(old_addr));
> > +
> > +     if (clp_addr.ss_family != old_addr.ss_family)
> > +             return;
> > +
> > +     xprt_args.dstaddr = clp_sap;
> > +     xprt_args.addrlen = clp_salen;
> > +
> > +     xprtdata.cred = nfs4_get_clid_cred(old);
> > +     rpc_clnt_add_xprt(old->cl_rpcclient, &xprt_args,
> > +                       rpc_clnt_setup_test_and_add_xprt, &rpcdata);
>
> Is there an upper bound on the number of transports that
> are added to the NFS client's switch?

I don't believe any limits exist right now. Why should there be a
limit? Are you saying that the client should limit trunking? While
this is not what's happening here, but say FS_LOCATION returned 100
ips for the server. Are you saying the client should be limiting how
many trunkable connections it would be establishing and picking just a
few addresses to try? What's happening with this patch is that say
there are 100mounts to 100 ips (each representing the same server or
trunkable server(s)), without this patch a single connection is kept,
with this patch we'll have 100 connections.

>
>
> > +
> > +     if (xprtdata.cred)
> > +             put_cred(xprtdata.cred);
> > +}
> > +
> > /**
> >  * nfs4_init_client - Initialise an NFS4 client record
> >  *
> > @@ -434,6 +472,8 @@ struct nfs_client *nfs4_init_client(struct nfs_client *clp,
> >                * won't try to use it.
> >                */
> >               nfs_mark_client_ready(clp, -EPERM);
> > +             if (old->cl_mvops->session_trunk)
> > +                     nfs4_add_trunk(clp, old);
> >       }
> >       clear_bit(NFS_CS_TSM_POSSIBLE, &clp->cl_flags);
> >       nfs_put_client(clp);
> > --
> > 2.27.0
> >
>
> --
> Chuck Lever
>
>
>