On Mar 18, 2014, at 15:00, Steve Dickson <SteveD@xxxxxxxxxx> 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@xxxxxxxxxx> 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@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++;
>>>>>>
>>>>> 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@xxxxxxxxxxxxxxx
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