On Thu, 25 Sep 2014 21:23:35 -0400 Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote: > On Thu, Sep 25, 2014 at 9:10 PM, NeilBrown <neilb@xxxxxxx> wrote: > > On Wed, 24 Sep 2014 22:51:19 -0400 Trond Myklebust > > <trond.myklebust@xxxxxxxxxxxxxxx> wrote: > > > >> The flag RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT was intended introduced in > >> order to allow NFSv4 clients to disable resend timeouts. Since those > >> cause the RPC layer to break the connection, they mess up the duplicate > >> reply caches that remain indexed on the port number in NFSv4.. > >> > >> This patch includes the code that was missing in the original to > >> set the appropriate flag in struct rpc_clnt, when the caller of > >> rpc_create() sets RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT. > >> > >> Fixes: 8a19a0b6cb2e (SUNRPC: Add RPC task and client level options to...) > >> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> > >> --- > >> net/sunrpc/clnt.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c > >> index 488ddeed9363..841565450354 100644 > >> --- a/net/sunrpc/clnt.c > >> +++ b/net/sunrpc/clnt.c > >> @@ -461,6 +461,8 @@ struct rpc_clnt *rpc_create_xprt(struct rpc_create_args *args, > >> > >> if (args->flags & RPC_CLNT_CREATE_AUTOBIND) > >> clnt->cl_autobind = 1; > >> + if (args->flags & RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT) > >> + clnt->cl_noretranstimeo = 1; > >> if (args->flags & RPC_CLNT_CREATE_DISCRTRY) > >> clnt->cl_discrtry = 1; > >> if (!(args->flags & RPC_CLNT_CREATE_QUIET)) > > > > Hi Trond, > > do this relate to my observation in > > Subject: Re: NFS auto-reconnect tuning > > > > that NFSv4 closes a connections after the first timeout? > > This patch seems to be a step towards changing that behaviour, though it > > doesn't succeed. > > > > You would need > > > > @@ -580,6 +582,7 @@ static struct rpc_clnt *__rpc_clone_client(struct rpc_create_args *args, > > new->cl_autobind = 0; > > new->cl_softrtry = clnt->cl_softrtry; > > new->cl_discrtry = clnt->cl_discrtry; > > + new->cl_noretranstimeo = clnt->cl_noretranstimeo; > > D'oh! Yes, of course that is correct. > > > new->cl_chatty = clnt->cl_chatty; > > return new; > > > > as well. > > > > What do you think of having the client close the connection more quickly when > > there is a timeout? There does seem to be a case for closing sooner than 30 > > minutes... > > > > I must admit I'm a bit confused by these flags so I might be missing > > something important. > > Actually, the whole idea is to stop the client from disconnecting when > it doesn't need to. Disconnect == very bad, since it typically breaks > the duplicate reply cache semantics and it can interrupt RPC calls > that may be in progress on the server. > Furthermore, the NFSv4 server is supposed to guarantee to us that it > will always reply to an RPC call (provided that the connection stays > up), so the whole business of disconnecting was misguided in the first > place. The only thing we need is to detect accidental disconnections > (i.e. network partitions), and the way to do that is to use TCP > keepalive. The new code will therefore interpret the NFSv4 'timeo' > mount parameter as the TCP keepalive timeout rather than as a > retransmission timeout. > OK - that makes sense. A problem is that TCP keepalives don't help when you change the local IP address. tcp_keepalive_timer() sees that tcp_send_head() is always non-NULL (presumably a packet that it is trying to send but cannot be) and so it just keeps waiting. I guess I should raise this on net-dev .... Thanks, NeilBrown
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