Re: [PATCH v2] SUNRPC: Initialize rpc_rqst outside of xprt->reserve_lock

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> On Apr 3, 2018, at 4:38 PM, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
> 
> 
> 
>> On Apr 3, 2018, at 4:12 PM, Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> wrote:
>> 
>> Hi Chuck,
>> 
>> On 03/11/2018 11:27 AM, Chuck Lever wrote:
>>> alloc_slot is a transport-specific op, but initializing an rpc_rqst
>>> is common to all transports. In addition, the only part of initial-
>>> izing an rpc_rqst that needs serialization is getting a fresh XID.
>>> 
>>> Move rpc_rqst initialization to common code in preparation for
>>> adding a transport-specific alloc_slot to xprtrdma.
>> 
>> I'm having trouble with this patch again.  This time I'm running xfstests generic/074 with NFS v4.0, and my client starts seeing "nfs: server 192.168.100.215 not responding, still trying" after about a minute.  Any thoughts about what's going on here?
> 
> Random thoughts:
> 
> "nfs: server not responding" is a very generic failure. One
> minute is the TCP timeout setting. NFSv4.0 clients don't
> typically retransmit unless the server drops the connection.

Another thought:

The problem before was that the client didn't recognize an XID
returned by the server because the client had overwritten the
rqst's rq_xid field. It should be straightforward to have
xprt_lookup_rqst complain about an unrecognized XID, to confirm
that this is happening again. Or there might even be a counter
somewhere that you can view with a tool like mountstats.


> What is your client, server, and network configuration?
> 
> Can you reproduce with NFSv3 or NFSv4.1? I assume you are
> using TCP for this test.
> 
> Any other relevant messages in the client's or server's /v/l/m?
> 
> 
>> I keep trying to capture it with Wireshark, but there are enough packets on the wire to crash Wireshark.
> 
> Use tcpdump instead, and capture into a tmpfs.
> 
> 
>> Thoughts?
>> Anna
>> 
>>> 
>>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>>> ---
>>> include/linux/sunrpc/xprt.h |    1 +
>>> net/sunrpc/clnt.c           |    1 +
>>> net/sunrpc/xprt.c           |   12 +++++++-----
>>> 3 files changed, 9 insertions(+), 5 deletions(-)
>>> 
>>> Changes since v1:
>>> - Partial sends should not bump the XID
>>> 
>>> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
>>> index 5fea0fb..9784e28 100644
>>> --- a/include/linux/sunrpc/xprt.h
>>> +++ b/include/linux/sunrpc/xprt.h
>>> @@ -324,6 +324,7 @@ struct xprt_class {
>>> struct rpc_xprt		*xprt_create_transport(struct xprt_create *args);
>>> void			xprt_connect(struct rpc_task *task);
>>> void			xprt_reserve(struct rpc_task *task);
>>> +void			xprt_request_init(struct rpc_task *task);
>>> void			xprt_retry_reserve(struct rpc_task *task);
>>> int			xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
>>> int			xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);
>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
>>> index 6e432ec..226f558 100644
>>> --- a/net/sunrpc/clnt.c
>>> +++ b/net/sunrpc/clnt.c
>>> @@ -1546,6 +1546,7 @@ void rpc_force_rebind(struct rpc_clnt *clnt)
>>> 	task->tk_status = 0;
>>> 	if (status >= 0) {
>>> 		if (task->tk_rqstp) {
>>> +			xprt_request_init(task);
>>> 			task->tk_action = call_refresh;
>>> 			return;
>>> 		}
>>> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
>>> index 70f0050..2d95926 100644
>>> --- a/net/sunrpc/xprt.c
>>> +++ b/net/sunrpc/xprt.c
>>> @@ -66,7 +66,7 @@
>>> * Local functions
>>> */
>>> static void	 xprt_init(struct rpc_xprt *xprt, struct net *net);
>>> -static void	xprt_request_init(struct rpc_task *, struct rpc_xprt *);
>>> +static __be32	xprt_alloc_xid(struct rpc_xprt *xprt);
>>> static void	xprt_connect_status(struct rpc_task *task);
>>> static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
>>> static void     __xprt_put_cong(struct rpc_xprt *, struct rpc_rqst *);
>>> @@ -987,6 +987,8 @@ bool xprt_prepare_transmit(struct rpc_task *task)
>>> 		task->tk_status = -EAGAIN;
>>> 		goto out_unlock;
>>> 	}
>>> +	if (!bc_prealloc(req) && !req->rq_xmit_bytes_sent)
>>> +		req->rq_xid = xprt_alloc_xid(xprt);
>>> 	ret = true;
>>> out_unlock:
>>> 	spin_unlock_bh(&xprt->transport_lock);
>>> @@ -1163,10 +1165,10 @@ void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
>>> out_init_req:
>>> 	xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
>>> 				     xprt->num_reqs);
>>> +	spin_unlock(&xprt->reserve_lock);
>>> +
>>> 	task->tk_status = 0;
>>> 	task->tk_rqstp = req;
>>> -	xprt_request_init(task, xprt);
>>> -	spin_unlock(&xprt->reserve_lock);
>>> }
>>> EXPORT_SYMBOL_GPL(xprt_alloc_slot);
>>> 
>>> @@ -1303,8 +1305,9 @@ static inline void xprt_init_xid(struct rpc_xprt *xprt)
>>> 	xprt->xid = prandom_u32();
>>> }
>>> 
>>> -static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
>>> +void xprt_request_init(struct rpc_task *task)
>>> {
>>> +	struct rpc_xprt *xprt = task->tk_xprt;
>>> 	struct rpc_rqst	*req = task->tk_rqstp;
>>> 
>>> 	INIT_LIST_HEAD(&req->rq_list);
>>> @@ -1312,7 +1315,6 @@ static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
>>> 	req->rq_task	= task;
>>> 	req->rq_xprt    = xprt;
>>> 	req->rq_buffer  = NULL;
>>> -	req->rq_xid     = xprt_alloc_xid(xprt);
>>> 	req->rq_connect_cookie = xprt->connect_cookie - 1;
>>> 	req->rq_bytes_sent = 0;
>>> 	req->rq_snd_buf.len = 0;
>>> 
> 
> --
> Chuck Lever
> 
> 
> 
> --
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--
Chuck Lever



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