[PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

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@primarydata.com>
---
 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++;
-- 
1.8.5.3

[PATCH 2/2] SUNRPC: Ensure that call_bind times out correctly

[Trond Myklebust]

If the rpcbind server is unavailable, we still want the RPC client
to respect the timeout.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
 net/sunrpc/clnt.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index f22d3a115fda..53a13835b90f 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1728,9 +1728,7 @@ call_bind_status(struct rpc_task *task)
 	case -EPROTONOSUPPORT:
 		dprintk("RPC: %5u remote rpcbind version unavailable, retrying\n",
 				task->tk_pid);
-		task->tk_status = 0;
-		task->tk_action = call_bind;
-		return;
+		goto retry_timeout;
 	case -ECONNREFUSED:		/* connection problems */
 	case -ECONNRESET:
 	case -ECONNABORTED:
@@ -1756,6 +1754,7 @@ call_bind_status(struct rpc_task *task)
 	return;
 
 retry_timeout:
+	task->tk_status = 0;
 	task->tk_action = call_timeout;
 }
 
-- 
1.8.5.3

Re: [PATCH 2/2] SUNRPC: Ensure that call_bind times out correctly

[Steve Dickson]

On 03/17/2014 02:40 PM, Trond Myklebust wrote:
> If the rpcbind server is unavailable, we still want the RPC client
> to respect the timeout.
> 
> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Tested-by: Steve Dickson <steved@redhat.com>

steved.

> ---
>  net/sunrpc/clnt.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index f22d3a115fda..53a13835b90f 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -1728,9 +1728,7 @@ call_bind_status(struct rpc_task *task)
>  	case -EPROTONOSUPPORT:
>  		dprintk("RPC: %5u remote rpcbind version unavailable, retrying\n",
>  				task->tk_pid);
> -		task->tk_status = 0;
> -		task->tk_action = call_bind;
> -		return;
> +		goto retry_timeout;
>  	case -ECONNREFUSED:		/* connection problems */
>  	case -ECONNRESET:
>  	case -ECONNABORTED:
> @@ -1756,6 +1754,7 @@ call_bind_status(struct rpc_task *task)
>  	return;
>  
>  retry_timeout:
> +	task->tk_status = 0;
>  	task->tk_action = call_timeout;
>  }
>  
> 

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

Hey,

On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
> ---
>  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++;
> 
How is this support to work if the trunking code still ignores timeouts? 

[ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying

steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:

> Hey,
> 
> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
>> ---
>> 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++;
>> 
> How is this support to work if the trunking code still ignores timeouts? 
> 
> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying

The above patch fixes the regression that Neil tracked down in Linux 3.12, and that affects the generic RPC handling of soft timeouts.

The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.

_________________________________
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/18/2014 11:58 AM, Trond Myklebust wrote:
> 
> On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:
> 
>> Hey,
>>
>> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
>>> ---
>>> 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++;
>>>
>> How is this support to work if the trunking code still ignores timeouts? 
>>
>> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying
> 
> The above patch fixes the regression that Neil tracked down in Linux 3.12, and that 
> affects the generic RPC handling of soft timeouts.
> 
> The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
> and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
Maybe it been broken that long.... :-) 

But here is the obvious loop that stop that hangs a mount forever:

 #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
 #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
#10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
#11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
#12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
#13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
#14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
#15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
#16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
#17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9

The SETCLIENT times out 
   NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
   NFS reply setclientid: -110

The nfs4_discover_server_trunking() retries 
   NFS: nfs4_discover_server_trunking after status -110, retrying

The happens when there server is down and so the connections 
fail with ECONNREFUSED:
   RPC:     2 call_connect_status (status -111)

The mount system call never times out in which it did in the past. 

So who do I get the system call to time out again?

steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

On Tue, 2014-03-18 at 13:24 -0400, Steve Dickson wrote:
> 
> On 03/18/2014 11:58 AM, Trond Myklebust wrote:
> > 
> > On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:
> > 
> >> Hey,
> >>
> >> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
> >>> ---
> >>> 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++;
> >>>
> >> How is this support to work if the trunking code still ignores timeouts? 
> >>
> >> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying
> > 
> > The above patch fixes the regression that Neil tracked down in Linux 3.12, and that 
> > affects the generic RPC handling of soft timeouts.
> > 
> > The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
> > and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
> Maybe it been broken that long.... :-) 
> 
> But here is the obvious loop that stop that hangs a mount forever:
> 
>  #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
>  #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
> #10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
> #11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
> #12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
> #13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
> #14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
> #15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
> #16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
> #17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9
> 
> The SETCLIENT times out 
>    NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
>    NFS reply setclientid: -110
> 
> The nfs4_discover_server_trunking() retries 
>    NFS: nfs4_discover_server_trunking after status -110, retrying
> 
> The happens when there server is down and so the connections 
> fail with ECONNREFUSED:
>    RPC:     2 call_connect_status (status -111)
> 
> The mount system call never times out in which it did in the past. 

Why should a mount system call time out other than perhaps in the case
of a soft mount?

-- 
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/18/2014 02:45 PM, Trond Myklebust wrote:
> On Tue, 2014-03-18 at 13:24 -0400, Steve Dickson wrote:
>>
>> On 03/18/2014 11:58 AM, Trond Myklebust wrote:
>>>
>>> On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:
>>>
>>>> Hey,
>>>>
>>>> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
>>>>> ---
>>>>> 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++;
>>>>>
>>>> How is this support to work if the trunking code still ignores timeouts? 
>>>>
>>>> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying
>>>
>>> The above patch fixes the regression that Neil tracked down in Linux 3.12, and that 
>>> affects the generic RPC handling of soft timeouts.
>>>
>>> The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
>>> and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
>> Maybe it been broken that long.... :-) 
>>
>> But here is the obvious loop that stop that hangs a mount forever:
>>
>>  #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
>>  #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
>> #10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
>> #11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
>> #12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
>> #13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
>> #14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
>> #15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
>> #16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
>> #17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9
>>
>> The SETCLIENT times out 
>>    NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
>>    NFS reply setclientid: -110
>>
>> The nfs4_discover_server_trunking() retries 
>>    NFS: nfs4_discover_server_trunking after status -110, retrying
>>
>> The happens when there server is down and so the connections 
>> fail with ECONNREFUSED:
>>    RPC:     2 call_connect_status (status -111)
>>
>> The mount system call never times out in which it did in the past. 
> 
> Why should a mount system call time out other than perhaps in the case
> of a soft mount?
> 
So the mount can go in background. As you know the -o bg is used in
the /etc/fstab so the boot does not get hung up with downed servers. 
That's how it always worked... 

steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

On Mar 18, 2014, at 15:00, Steve Dickson <SteveD@redhat.com> wrote:

> 
> 
> On 03/18/2014 02:45 PM, Trond Myklebust wrote:
>> On Tue, 2014-03-18 at 13:24 -0400, Steve Dickson wrote:
>>> 
>>> On 03/18/2014 11:58 AM, Trond Myklebust wrote:
>>>> 
>>>> On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:
>>>> 
>>>>> Hey,
>>>>> 
>>>>> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
>>>>>> ---
>>>>>> 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++;
>>>>>> 
>>>>> How is this support to work if the trunking code still ignores timeouts? 
>>>>> 
>>>>> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying
>>>> 
>>>> The above patch fixes the regression that Neil tracked down in Linux 3.12, and that 
>>>> affects the generic RPC handling of soft timeouts.
>>>> 
>>>> The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
>>>> and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
>>> Maybe it been broken that long.... :-) 
>>> 
>>> But here is the obvious loop that stop that hangs a mount forever:
>>> 
>>> #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
>>> #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
>>> #10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
>>> #11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
>>> #12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
>>> #13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
>>> #14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
>>> #15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
>>> #16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
>>> #17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9
>>> 
>>> The SETCLIENT times out 
>>>   NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
>>>   NFS reply setclientid: -110
>>> 
>>> The nfs4_discover_server_trunking() retries 
>>>   NFS: nfs4_discover_server_trunking after status -110, retrying
>>> 
>>> The happens when there server is down and so the connections 
>>> fail with ECONNREFUSED:
>>>   RPC:     2 call_connect_status (status -111)
>>> 
>>> The mount system call never times out in which it did in the past. 
>> 
>> Why should a mount system call time out other than perhaps in the case
>> of a soft mount?
>> 
> So the mount can go in background. As you know the -o bg is used in
> the /etc/fstab so the boot does not get hung up with downed servers. 
> That's how it always worked... 

No. As I’ve told you already, this has never worked correctly for NFSv4, and is not expected to work even if we do change the trunking discovery because path walks etc will still hang. Please do this in userland as previously suggested.

_________________________________
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/18/2014 03:50 PM, Trond Myklebust wrote:
> 
> On Mar 18, 2014, at 15:00, Steve Dickson <SteveD@redhat.com> wrote:
> 
>>
>>
>> On 03/18/2014 02:45 PM, Trond Myklebust wrote:
>>> On Tue, 2014-03-18 at 13:24 -0400, Steve Dickson wrote:
>>>>
>>>> On 03/18/2014 11:58 AM, Trond Myklebust wrote:
>>>>>
>>>>> On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:
>>>>>
>>>>>> Hey,
>>>>>>
>>>>>> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
>>>>>>> ---
>>>>>>> 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++;
>>>>>>>
>>>>>> How is this support to work if the trunking code still ignores timeouts? 
>>>>>>
>>>>>> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying
>>>>>
>>>>> The above patch fixes the regression that Neil tracked down in Linux 3.12, and that 
>>>>> affects the generic RPC handling of soft timeouts.
>>>>>
>>>>> The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
>>>>> and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
>>>> Maybe it been broken that long.... :-) 
>>>>
>>>> But here is the obvious loop that stop that hangs a mount forever:
>>>>
>>>> #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
>>>> #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
>>>> #10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
>>>> #11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
>>>> #12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
>>>> #13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
>>>> #14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
>>>> #15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
>>>> #16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
>>>> #17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9
>>>>
>>>> The SETCLIENT times out 
>>>>   NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
>>>>   NFS reply setclientid: -110
>>>>
>>>> The nfs4_discover_server_trunking() retries 
>>>>   NFS: nfs4_discover_server_trunking after status -110, retrying
>>>>
>>>> The happens when there server is down and so the connections 
>>>> fail with ECONNREFUSED:
>>>>   RPC:     2 call_connect_status (status -111)
>>>>
>>>> The mount system call never times out in which it did in the past. 
>>>
>>> Why should a mount system call time out other than perhaps in the case
>>> of a soft mount?
>>>
>> So the mount can go in background. As you know the -o bg is used in
>> the /etc/fstab so the boot does not get hung up with downed servers. 
>> That's how it always worked... 
> 
> No. As I’ve told you already, this has never worked correctly for 
> NFSv4, and is not expected to work even if we do change the 
> trunking discovery because path walks etc will still hang. 
Just to be clear... Are you saying that v4 mounts can/will hang 
in the kernel forever regardless of what the timeout and 
retry mount options are?

> Please do this in userland as previously suggested.
If the above is indeed the case, then I'll have to use signals 
to interrupt the foreground mount...

But, if setting mount options like
   http://www.spinics.net/lists/linux-nfs/msg41993.html

will guarantee will indeed timeout in a timely manner,
than I would rather using the mount options instead
of introducing signals into the mix... 

steved. 

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

On Mar 19, 2014, at 8:39, Steve Dickson <SteveD@redhat.com> wrote:

> 
> 
> On 03/18/2014 03:50 PM, Trond Myklebust wrote:
>> 
>> On Mar 18, 2014, at 15:00, Steve Dickson <SteveD@redhat.com> wrote:
>> 
>>> 
>>> 
>>> On 03/18/2014 02:45 PM, Trond Myklebust wrote:
>>>> On Tue, 2014-03-18 at 13:24 -0400, Steve Dickson wrote:
>>>>> 
>>>>> On 03/18/2014 11:58 AM, Trond Myklebust wrote:
>>>>>> 
>>>>>> On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:
>>>>>> 
>>>>>>> Hey,
>>>>>>> 
>>>>>>> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
>>>>>>>> ---
>>>>>>>> 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++;
>>>>>>>> 
>>>>>>> How is this support to work if the trunking code still ignores timeouts? 
>>>>>>> 
>>>>>>> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying
>>>>>> 
>>>>>> The above patch fixes the regression that Neil tracked down in Linux 3.12, and that 
>>>>>> affects the generic RPC handling of soft timeouts.
>>>>>> 
>>>>>> The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
>>>>>> and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
>>>>> Maybe it been broken that long.... :-) 
>>>>> 
>>>>> But here is the obvious loop that stop that hangs a mount forever:
>>>>> 
>>>>> #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
>>>>> #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
>>>>> #10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
>>>>> #11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
>>>>> #12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
>>>>> #13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
>>>>> #14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
>>>>> #15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
>>>>> #16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
>>>>> #17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9
>>>>> 
>>>>> The SETCLIENT times out 
>>>>>  NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
>>>>>  NFS reply setclientid: -110
>>>>> 
>>>>> The nfs4_discover_server_trunking() retries 
>>>>>  NFS: nfs4_discover_server_trunking after status -110, retrying
>>>>> 
>>>>> The happens when there server is down and so the connections 
>>>>> fail with ECONNREFUSED:
>>>>>  RPC:     2 call_connect_status (status -111)
>>>>> 
>>>>> The mount system call never times out in which it did in the past. 
>>>> 
>>>> Why should a mount system call time out other than perhaps in the case
>>>> of a soft mount?
>>>> 
>>> So the mount can go in background. As you know the -o bg is used in
>>> the /etc/fstab so the boot does not get hung up with downed servers. 
>>> That's how it always worked... 
>> 
>> No. As I’ve told you already, this has never worked correctly for 
>> NFSv4, and is not expected to work even if we do change the 
>> trunking discovery because path walks etc will still hang. 
> Just to be clear... Are you saying that v4 mounts can/will hang 
> in the kernel forever regardless of what the timeout and 
> retry mount options are?

I’m saying that we should respect the ‘soft’ mount option, but we shouldn’t need to add any new special features for the mount call.

>> Please do this in userland as previously suggested.
> If the above is indeed the case, then I'll have to use signals 
> to interrupt the foreground mount...
> 
> But, if setting mount options like
>   http://www.spinics.net/lists/linux-nfs/msg41993.html
> 
> will guarantee will indeed timeout in a timely manner,
> than I would rather using the mount options instead
> of introducing signals into the mix… 

For the case of NFSv4:

1) ‘retry' is pretty much obsolete, since the protocol tells us we must not resend unless the connection breaks. All it does today is to act as a multiplier for ‘timeo’.
2) ‘timeo’ itself only has a user-visible effect when you request a soft mount or a soft RPC call. Otherwise, its main effect is to tell the socket when to ping the server with a TCP ‘keepalive’.

_________________________________
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/19/2014 08:52 AM, Trond Myklebust wrote:
> 
> On Mar 19, 2014, at 8:39, Steve Dickson <SteveD@redhat.com> wrote:
> 
>>
>>
>> On 03/18/2014 03:50 PM, Trond Myklebust wrote:
>>>
>>> On Mar 18, 2014, at 15:00, Steve Dickson <SteveD@redhat.com> wrote:
>>>
>>>>
>>>>
>>>> On 03/18/2014 02:45 PM, Trond Myklebust wrote:
>>>>> On Tue, 2014-03-18 at 13:24 -0400, Steve Dickson wrote:
>>>>>>
>>>>>> On 03/18/2014 11:58 AM, Trond Myklebust wrote:
>>>>>>>
>>>>>>> On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:
>>>>>>>
>>>>>>>> Hey,
>>>>>>>>
>>>>>>>> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
>>>>>>>>> ---
>>>>>>>>> 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++;
>>>>>>>>>
>>>>>>>> How is this support to work if the trunking code still ignores timeouts? 
>>>>>>>>
>>>>>>>> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying
>>>>>>>
>>>>>>> The above patch fixes the regression that Neil tracked down in Linux 3.12, and that 
>>>>>>> affects the generic RPC handling of soft timeouts.
>>>>>>>
>>>>>>> The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
>>>>>>> and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
>>>>>> Maybe it been broken that long.... :-) 
>>>>>>
>>>>>> But here is the obvious loop that stop that hangs a mount forever:
>>>>>>
>>>>>> #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
>>>>>> #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
>>>>>> #10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
>>>>>> #11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
>>>>>> #12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
>>>>>> #13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
>>>>>> #14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
>>>>>> #15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
>>>>>> #16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
>>>>>> #17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9
>>>>>>
>>>>>> The SETCLIENT times out 
>>>>>>  NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
>>>>>>  NFS reply setclientid: -110
>>>>>>
>>>>>> The nfs4_discover_server_trunking() retries 
>>>>>>  NFS: nfs4_discover_server_trunking after status -110, retrying
>>>>>>
>>>>>> The happens when there server is down and so the connections 
>>>>>> fail with ECONNREFUSED:
>>>>>>  RPC:     2 call_connect_status (status -111)
>>>>>>
>>>>>> The mount system call never times out in which it did in the past. 
>>>>>
>>>>> Why should a mount system call time out other than perhaps in the case
>>>>> of a soft mount?
>>>>>
>>>> So the mount can go in background. As you know the -o bg is used in
>>>> the /etc/fstab so the boot does not get hung up with downed servers. 
>>>> That's how it always worked... 
>>>
>>> No. As I’ve told you already, this has never worked correctly for 
>>> NFSv4, and is not expected to work even if we do change the 
>>> trunking discovery because path walks etc will still hang. 
>> Just to be clear... Are you saying that v4 mounts can/will hang 
>> in the kernel forever regardless of what the timeout and 
>> retry mount options are?
> 
> I’m saying that we should respect the ‘soft’ mount option, but we shouldn’t need to add any new special features for the mount call.
> 
>>> Please do this in userland as previously suggested.
>> If the above is indeed the case, then I'll have to use signals 
>> to interrupt the foreground mount...
>>
>> But, if setting mount options like
>>   http://www.spinics.net/lists/linux-nfs/msg41993.html
>>
>> will guarantee will indeed timeout in a timely manner,
>> than I would rather using the mount options instead
>> of introducing signals into the mix… 
> 
> For the case of NFSv4:
> 
> 1) ‘retry' is pretty much obsolete, since the protocol tells us 
>     we must not resend unless the connection breaks. All it does 
>     today is to act as a multiplier for ‘timeo’.
I saw that.... I was thinking '1' was a better multiplier that
the default... but it appears it does not matter... 

> 2) ‘timeo’ itself only has a user-visible effect when you request 
>     a soft mount or a soft RPC call. Otherwise, its main effect is 
>     to tell the socket when to ping the server with a TCP ‘keepalive’.
Setting 'timeo=100' really cuts down the foreground timeout. Without 
it takes over three minutes for the fg to timeout. Setting it
to 100, brings the timeout to 30 seconds, consistently 

Question. You mention some about "path walks etc will still hang".
I'm assuming we would get to those hangs because we were able
to connect the server. My question is would make sense to 
interrupt out of those "path walks"? Maybe its just a slow
server??

steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

On Mar 19, 2014, at 10:07, Steve Dickson <SteveD@redhat.com> wrote:

> 
> 
> On 03/19/2014 08:52 AM, Trond Myklebust wrote:
>> 
>> On Mar 19, 2014, at 8:39, Steve Dickson <SteveD@redhat.com> wrote:
>> 
>>> 
>>> 
>>> On 03/18/2014 03:50 PM, Trond Myklebust wrote:
>>>> 
>>>> On Mar 18, 2014, at 15:00, Steve Dickson <SteveD@redhat.com> wrote:
>>>> 
>>>>> 
>>>>> 
>>>>> On 03/18/2014 02:45 PM, Trond Myklebust wrote:
>>>>>> On Tue, 2014-03-18 at 13:24 -0400, Steve Dickson wrote:
>>>>>>> 
>>>>>>> On 03/18/2014 11:58 AM, Trond Myklebust wrote:
>>>>>>>> 
>>>>>>>> On Mar 18, 2014, at 11:47, Steve Dickson <SteveD@redhat.com> wrote:
>>>>>>>> 
>>>>>>>>> Hey,
>>>>>>>>> 
>>>>>>>>> On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
>>>>>>>>>> ---
>>>>>>>>>> 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++;
>>>>>>>>>> 
>>>>>>>>> How is this support to work if the trunking code still ignores timeouts? 
>>>>>>>>> 
>>>>>>>>> [ 2076.045176] NFS: nfs4_discover_server_trunking after status -110, retrying
>>>>>>>> 
>>>>>>>> The above patch fixes the regression that Neil tracked down in Linux 3.12, and that 
>>>>>>>> affects the generic RPC handling of soft timeouts.
>>>>>>>> 
>>>>>>>> The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
>>>>>>>> and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
>>>>>>> Maybe it been broken that long.... :-) 
>>>>>>> 
>>>>>>> But here is the obvious loop that stop that hangs a mount forever:
>>>>>>> 
>>>>>>> #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
>>>>>>> #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
>>>>>>> #10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
>>>>>>> #11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
>>>>>>> #12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
>>>>>>> #13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
>>>>>>> #14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
>>>>>>> #15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
>>>>>>> #16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
>>>>>>> #17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9
>>>>>>> 
>>>>>>> The SETCLIENT times out 
>>>>>>> NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
>>>>>>> NFS reply setclientid: -110
>>>>>>> 
>>>>>>> The nfs4_discover_server_trunking() retries 
>>>>>>> NFS: nfs4_discover_server_trunking after status -110, retrying
>>>>>>> 
>>>>>>> The happens when there server is down and so the connections 
>>>>>>> fail with ECONNREFUSED:
>>>>>>> RPC:     2 call_connect_status (status -111)
>>>>>>> 
>>>>>>> The mount system call never times out in which it did in the past. 
>>>>>> 
>>>>>> Why should a mount system call time out other than perhaps in the case
>>>>>> of a soft mount?
>>>>>> 
>>>>> So the mount can go in background. As you know the -o bg is used in
>>>>> the /etc/fstab so the boot does not get hung up with downed servers. 
>>>>> That's how it always worked... 
>>>> 
>>>> No. As I’ve told you already, this has never worked correctly for 
>>>> NFSv4, and is not expected to work even if we do change the 
>>>> trunking discovery because path walks etc will still hang. 
>>> Just to be clear... Are you saying that v4 mounts can/will hang 
>>> in the kernel forever regardless of what the timeout and 
>>> retry mount options are?
>> 
>> I’m saying that we should respect the ‘soft’ mount option, but we shouldn’t need to add any new special features for the mount call.
>> 
>>>> Please do this in userland as previously suggested.
>>> If the above is indeed the case, then I'll have to use signals 
>>> to interrupt the foreground mount...
>>> 
>>> But, if setting mount options like
>>>  http://www.spinics.net/lists/linux-nfs/msg41993.html
>>> 
>>> will guarantee will indeed timeout in a timely manner,
>>> than I would rather using the mount options instead
>>> of introducing signals into the mix… 
>> 
>> For the case of NFSv4:
>> 
>> 1) ‘retry' is pretty much obsolete, since the protocol tells us 
>>    we must not resend unless the connection breaks. All it does 
>>    today is to act as a multiplier for ‘timeo’.
> I saw that.... I was thinking '1' was a better multiplier that
> the default... but it appears it does not matter... 
> 
>> 2) ‘timeo’ itself only has a user-visible effect when you request 
>>    a soft mount or a soft RPC call. Otherwise, its main effect is 
>>    to tell the socket when to ping the server with a TCP ‘keepalive’.
> Setting 'timeo=100' really cuts down the foreground timeout. Without 
> it takes over three minutes for the fg to timeout. Setting it
> to 100, brings the timeout to 30 seconds, consistently 

Yes, but a 10 second soft timeout can screw you over badly if your server crashes or reboots at some point.

Tuning the mount ‘timeo’ and ‘retrans’ values purely to make the mount system call fast, would be like choosing sport shoes based solely on their ability to slip onto your feet faster: you may end up playing your game of football in a pair of clogs...

> Question. You mention some about "path walks etc will still hang".
> I'm assuming we would get to those hangs because we were able
> to connect the server. My question is would make sense to 
> interrupt out of those "path walks"? Maybe its just a slow
> server??

The kernel will continue to honour ‘soft’ in those path walks, so yes, if the server is slow, and it causes a timeout then that timeout is passed back to the user. That is fully in accordance with the documentation for ‘soft’.
If, however, the server crashes while we’re looking up the path as part of the mount call, and that mount call does not specify ‘soft’, then the client will hang until that server becomes available again. It will not return any errors. This behaviour has not changed since we first introduced NFSv4 in Linux 2.6.0 AFAIK, and there are no plans to change it.
Another consideration is that if the target directory on top of which you are mounting the new filesystem is itself NFS mounted, then the mount system call may hang if/when that server goes down. Again, the timeout behaviour will vary depending on the mount options that apply to that target directory.

IOW: there is no way to make mount.nfs honour the ‘retry’ and/or ‘bg' mount options in any consistent fashion by solely relying on kernel timeouts.

_________________________________
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/19/2014 11:04 AM, Trond Myklebust wrote:
> IOW: there is no way to make mount.nfs honour the ‘retry’ and/or ‘bg' 
> mount options in any consistent fashion by solely relying on kernel timeouts.
I went back and took a look at how bg mounts worked in a number of
older kernels f19(3.12) all the way back to RHEL6 kernel (2.6). 

I turns out you are right. The bg mounts were not depending on
timeouts they were depended on the mount to fail with ECONNREFUSED
The very first one, which is the reason the bg mount happen
so fast... 

Its seems these days ECONNREFUSED are no longer return 
as an error codes. They basically are turned into a 
timeout... Just curious as to why ECONNREFUSED are 
no longer returned?

Again, thanks for the cycles!

steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

On Wed, 2014-03-19 at 13:10 -0400, Steve Dickson wrote:
> 
> On 03/19/2014 11:04 AM, Trond Myklebust wrote:
> > IOW: there is no way to make mount.nfs honour the ‘retry’ and/or ‘bg' 
> > mount options in any consistent fashion by solely relying on kernel timeouts.
> I went back and took a look at how bg mounts worked in a number of
> older kernels f19(3.12) all the way back to RHEL6 kernel (2.6). 
> 
> I turns out you are right. The bg mounts were not depending on
> timeouts they were depended on the mount to fail with ECONNREFUSED
> The very first one, which is the reason the bg mount happen
> so fast... 
> 
> Its seems these days ECONNREFUSED are no longer return 
> as an error codes. They basically are turned into a 
> timeout... Just curious as to why ECONNREFUSED are 
> no longer returned?
> 
> Again, thanks for the cycles!

If the server is down during the initial rpc client creation, then I’d
still expect that to fail with ECONNREFUSED due to the rpc_ping() call.

Does the following patch help?


8<------------------------------------------------------------
>From dad628cc357a06cff8ce04300ba5c19bd92e73eb Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Wed, 19 Mar 2014 13:25:43 -0400
Subject: [PATCH] SUNRPC: Ensure call_status() deals correctly with SOFTCONN
 tasks

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
 net/sunrpc/clnt.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index cea1308a6fda..ef96568902c5 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -2004,6 +2004,10 @@ call_status(struct rpc_task *task)
 	case -EHOSTDOWN:
 	case -EHOSTUNREACH:
 	case -ENETUNREACH:
+		if (RPC_IS_SOFTCONN(task)) {
+			rpc_exit(task, status);
+			break;
+		}
 		/*
 		 * Delay any retries for 3 seconds, then handle as if it
 		 * were a timeout.
-- 
1.8.5.3


-- 
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/19/2014 01:29 PM, Trond Myklebust wrote:
> On Wed, 2014-03-19 at 13:10 -0400, Steve Dickson wrote:
>>
>> On 03/19/2014 11:04 AM, Trond Myklebust wrote:
>>> IOW: there is no way to make mount.nfs honour the ‘retry’ and/or ‘bg' 
>>> mount options in any consistent fashion by solely relying on kernel timeouts.
>> I went back and took a look at how bg mounts worked in a number of
>> older kernels f19(3.12) all the way back to RHEL6 kernel (2.6). 
>>
>> I turns out you are right. The bg mounts were not depending on
>> timeouts they were depended on the mount to fail with ECONNREFUSED
>> The very first one, which is the reason the bg mount happen
>> so fast... 
>>
>> Its seems these days ECONNREFUSED are no longer return 
>> as an error codes. They basically are turned into a 
>> timeout... Just curious as to why ECONNREFUSED are 
>> no longer returned?
>>
>> Again, thanks for the cycles!
> 
> If the server is down during the initial rpc client creation, then I’d
> still expect that to fail with ECONNREFUSED due to the rpc_ping() call.
> 
> Does the following patch help?
> 
> 
> 8<------------------------------------------------------------
> From dad628cc357a06cff8ce04300ba5c19bd92e73eb Mon Sep 17 00:00:00 2001
> From: Trond Myklebust <trond.myklebust@primarydata.com>
> Date: Wed, 19 Mar 2014 13:25:43 -0400
> Subject: [PATCH] SUNRPC: Ensure call_status() deals correctly with SOFTCONN
>  tasks
> 
> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
> ---
>  net/sunrpc/clnt.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index cea1308a6fda..ef96568902c5 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -2004,6 +2004,10 @@ call_status(struct rpc_task *task)
>  	case -EHOSTDOWN:
>  	case -EHOSTUNREACH:
>  	case -ENETUNREACH:
> +		if (RPC_IS_SOFTCONN(task)) {
> +			rpc_exit(task, status);
> +			break;
> +		}
>  		/*
>  		 * Delay any retries for 3 seconds, then handle as if it
>  		 * were a timeout.
> 
No... but I do thing that patch make sense... 

What's going on is-ECONNREFUSED is being seen in call_connect_status() 
and the task is not a soft connection. So call_timeout() is call which 
eventual times out the mount... 

So just for fun I make the SETCLIENTID rpc soft, but for some
reason that didn't work either... I thought for sure it would... 

steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

On Mar 19, 2014, at 14:22, Steve Dickson <SteveD@redhat.com> wrote:
> 
> What's going on is-ECONNREFUSED is being seen in call_connect_status() 
> and the task is not a soft connection. So call_timeout() is call which 
> eventual times out the mount… 

This is what is confusing me. I’d expect that the rpc_ping() would be the first thing to be sent on the wire by rpc_create(), and that ping should normally have the RPC_SOFTCONN flag set.

> So just for fun I make the SETCLIENTID rpc soft, but for some
> reason that didn't work either... I thought for sure it would... 
> 
> steved.

_________________________________
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/19/2014 03:41 PM, Trond Myklebust wrote:
> 
> On Mar 19, 2014, at 14:22, Steve Dickson <SteveD@redhat.com> wrote:
>>
>> What's going on is-ECONNREFUSED is being seen in call_connect_status() 
>> and the task is not a soft connection. So call_timeout() is call which 
>> eventual times out the mount… 
> 
> This is what is confusing me. I’d expect that the rpc_ping() would be the 
> first thing to be sent on the wire by rpc_create(), and that ping 
> should normally have the RPC_SOFTCONN flag set.
> 
>> So just for fun I make the SETCLIENTID rpc soft, but for some
>> reason that didn't work either... I thought for sure it would... 
I see you point... Using quick systemtap scripts it turns out
rpc_ping is not failing (returns 0x0) and it should because
the server is definitely down!  

steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/20/2014 10:12 AM, Steve Dickson wrote:
> 
> 
> On 03/19/2014 03:41 PM, Trond Myklebust wrote:
>>
>> On Mar 19, 2014, at 14:22, Steve Dickson <SteveD@redhat.com> wrote:
>>>
>>> What's going on is-ECONNREFUSED is being seen in call_connect_status() 
>>> and the task is not a soft connection. So call_timeout() is call which 
>>> eventual times out the mount… 
>>
>> This is what is confusing me. I’d expect that the rpc_ping() would be the 
>> first thing to be sent on the wire by rpc_create(), and that ping 
>> should normally have the RPC_SOFTCONN flag set.
>>
>>> So just for fun I make the SETCLIENTID rpc soft, but for some
>>> reason that didn't work either... I thought for sure it would... 
> I see you point... Using quick systemtap scripts it turns out
> rpc_ping is not failing (returns 0x0) and it should because
> the server is definitely down!  
Found it... The rpc_delay call in call_connect_status() 
is causing a callback to be scheduled and run before
rpc_exit_task. Unfortunately that call back (__rpc_atrun)
clears the status...

I'll posting my version of the fix shortly.. 

steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/18/2014 01:24 PM, Steve Dickson wrote:
>> The trunking code's handling of ETIMEDOUT has been there since Linux 3.7 
>> > and hasn’t changed, so I really don’t see how it can have worked at one time before 3.12.
> Maybe it been broken that long.... :-) 
> 
> But here is the obvious loop that stop that hangs a mount forever:
> 
>  #8 [ffff88007a22b7e8] rpc_call_sync at ffffffffa0220210 [sunrpc]
>  #9 [ffff88007a22b840] nfs4_proc_setclientid at ffffffffa0505c49 [nfsv4]
> #10 [ffff88007a22b988] nfs40_discover_server_trunking at ffffffffa0514489 [nfsv4]
> #11 [ffff88007a22b9d0] nfs4_discover_server_trunking at ffffffffa0516f2d [nfsv4]
> #12 [ffff88007a22ba28] nfs4_init_client at ffffffffa051e9a4 [nfsv4]
> #13 [ffff88007a22bb20] nfs_get_client at ffffffffa04bd6ba [nfs]
> #14 [ffff88007a22bb80] nfs4_set_client at ffffffffa051dfb0 [nfsv4]
> #15 [ffff88007a22bc00] nfs4_create_server at ffffffffa051f4ce [nfsv4]
> #16 [ffff88007a22bc88] nfs4_remote_mount at ffffffffa051790e [nfsv4]
> #17 [ffff88007a22bcb0] mount_fs at ffffffff811b3dd9
> 
> The SETCLIENT times out 
>    NFS call  setclientid auth=UNIX, 'Linux NFSv4.0 10.19.60.77/10.19.60.33 tcp'
>    NFS reply setclientid: -110
> 
> The nfs4_discover_server_trunking() retries 
>    NFS: nfs4_discover_server_trunking after status -110, retrying
> 
> The happens when there server is down and so the connections 
> fail with ECONNREFUSED:
>    RPC:     2 call_connect_status (status -111)
> 
> The mount system call never times out in which it did in the past. 
> 
> So who do I get the system call to time out again?
I'm thinking the problem here is the ECONNREFUSED is never
being passed up to the trunking code. The major timeout 
in call_timeout() turns the ECONNREFUSED into a ETIMEDOUT
So the trunking code never know the server is refusing
the connection... 

Why are ECONNREFUSED masked into ETIMEDOUTs? Should the 
ECONNREFUSED passed up?

steved.




> 
> steved.

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Steve Dickson]

On 03/17/2014 02:40 PM, Trond Myklebust 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@primarydata.com>
Tested-by: Steve Dickson <steved@redhat.com>

steved.
> ---
>  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++;
> 

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Jeff Layton]

On Mon, 17 Mar 2014 14:40:44 -0400
Trond Myklebust <trond.myklebust@primarydata.com> 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@primarydata.com>
> ---
>  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?

-- 
Jeff Layton <jlayton@redhat.com>

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Trond Myklebust]

On Apr 14, 2014, at 12:25, Jeff Layton <jlayton@redhat.com> wrote:

> On Mon, 17 Mar 2014 14:40:44 -0400
> Trond Myklebust <trond.myklebust@primarydata.com> 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@primarydata.com>
>> ---
>> 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@primarydata.com

Re: [PATCH 1/2] SUNRPC: Ensure that call_connect times out correctly

[Jeff Layton]

On Mon, 14 Apr 2014 12:57:58 -0400
Trond Myklebust <trond.myklebust@primarydata.com> wrote:

> 
> On Apr 14, 2014, at 12:25, Jeff Layton <jlayton@redhat.com> wrote:
> 
> > On Mon, 17 Mar 2014 14:40:44 -0400
> > Trond Myklebust <trond.myklebust@primarydata.com> 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@primarydata.com>
> >> ---
> >> 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@primarydata.com
> 

Well spotted. That does indeed fix it. I'll spin up a patch and send it
to Bruce.

Thanks!
-- 
Jeff Layton <jlayton@redhat.com>