On Apr 14, 2014, at 12:25, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> On Mon, 17 Mar 2014 14:40:44 -0400
> Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote:
>
>> When the server is unavailable due to a networking error, etc, we want
>> the RPC client to respect the timeout delays when attempting to reconnect.
>>
>> Fixes: 561ec1603171 (SUNRPC: call_connect_status should recheck bind..)
>> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>> ---
>> net/sunrpc/clnt.c | 8 +++-----
>> 1 file changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
>> index 0edada973434..f22d3a115fda 100644
>> --- a/net/sunrpc/clnt.c
>> +++ b/net/sunrpc/clnt.c
>> @@ -1798,10 +1798,6 @@ call_connect_status(struct rpc_task *task)
>> trace_rpc_connect_status(task, status);
>> task->tk_status = 0;
>> switch (status) {
>> - /* if soft mounted, test if we've timed out */
>> - case -ETIMEDOUT:
>> - task->tk_action = call_timeout;
>> - return;
>> case -ECONNREFUSED:
>> case -ECONNRESET:
>> case -ECONNABORTED:
>> @@ -1812,7 +1808,9 @@ call_connect_status(struct rpc_task *task)
>> if (RPC_IS_SOFTCONN(task))
>> break;
>> case -EAGAIN:
>> - task->tk_action = call_bind;
>> + case -ETIMEDOUT:
>> + /* Check if we've timed out before looping back to call_bind */
>> + task->tk_action = call_timeout;
>> return;
>> case 0:
>> clnt->cl_stats->netreconn++;
>
> I believe this patch may have broken the v4.0 callback channel
> establishment code in nfsd. I think what's happening is this:
>
> nfsd tries to create a RPC_TASK_SOFTCONN call to probe the cb channel
> with a CB_NULL. It queues the connect_worker to the workqueue. That
> establishes the socket and then gets a callback from the socket layer
> into xs_tcp_state_change for TCP_ESTABLISHED.
>
> That code does:
>
> xprt_wake_pending_tasks(xprt, -EAGAIN);
>
> ...that wakes the task up, and sets the tk_status to -EAGAIN, and it
> then moves on to call_timeout due to this patch. That code then does
> this:
>
> if (RPC_IS_SOFTCONN(task)) {
> rpc_exit(task, -ETIMEDOUT);
> return;
> }
>
> ...and the callback ping then fails with an error. Reverting this patch
> seems to fix it. I see several ways that we could fix this, but I'm not
> clear on the right way. Maybe we shouldn't be waking up the tasks with
> -EAGAIN in the TCP_ESTABLISHED case?
...or, possibly setup_callback_client should be setting the timeparms.to_maxval to a non-zero value so that xprt_adjust_timeout() and xprt_reset_majortimeo() behave as expected.
_________________________________
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@xxxxxxxxxxxxxxx
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