Bug 1367161

Split this bug off from 1337479

Fixed in 1337479:
If the unmount fails, the node no longer blocks

Remaining Issues:
The mount location on the node isn't fully cleaned up if NFS server down.

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+++ This bug was initially created as a clone of Bug #1337479 +++

Description of problem:
Create a pod using the NFS pv , after the nfs server is down , delete the pod ,new pod scheduled to the node will pendding

Version-Release number of selected component (if applicable):
openshift v3.2.0.44
kubernetes v1.2.0-36-g4a3f9c5
etcd 2.2.5


How reproducible:
always

Steps to Reproduce:
1.Add scc to allow user create privledge pod
wget https://raw.githubusercontent.com/openshift-qe/v3-testfiles/master/authorization/scc/scc_super_template.yaml
update the "#NAME#","NS",""
2.Create a nfs server
$oc create -f https://raw.githubusercontent.com/openshift-qe/v3-testfiles/master/storage/nfs/nfs-server.yaml
3.After the nfs server pod startup,create a pv using the nfs server 
wget https://raw.githubusercontent.com/openshift-qe/v3-testfiles/master/image/db-templates/auto-nfs-pv.json
update the template , correct the service ip to nfs server service ip
4. Create a app using the template mysql-persistent
oc new-app mysql-persistent
5. after the mysql pod startup successfuly,remember the node ip, delete the nfs service and pod
6. delete the mysql deployment config and pod
7. create new pod, and check the pod status

Actual results:
After step 6, all new pods scheduled to the node that mysql pod started in will be pending status 

Expected results:
New pod should work well.

Additional info:
After step 5 delete the mysql pod, the nfs volume mount point still exists on the node :
172.30.60.105:/ on /var/lib/origin/openshift.local.volumes/pods/bd4d801a-1d98-11e6-ad81-fa163e8f4eee/volumes/kubernetes.io~nfs/t95es type nfs4 (rw,relatime,vers=4.0,rsize=524288,wsize=524288,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.1.2.1,local_lock=none,addr=172.30.60.105)

and as the nfs server is down , we cannot umount successfully by :
umount /var/lib/origin/openshift.local.volumes/pods/bd4d801a-1d98-11e6-ad81-fa163e8f4eee/volumes/kubernetes.io~nfs/t95es

but after run :

umount -l /var/lib/origin/openshift.local.volumes/pods/bd4d801a-1d98-11e6-ad81-fa163e8f4eee/volumes/kubernetes.io~nfs/t95es

the node become working well.

--- Additional comment from  on 2016-06-10 14:28:50 EDT ---

when the nfs server is down, unmount will hang till timeout. It probably takes a while (300 seconds) till timeout happens.

--- Additional comment from Matthew Wong on 2016-06-14 10:01:12 EDT ---

I tried to replicate this and for me it hangs indefinitely (e.g. over the weekend). And the pod that uses the pv is stuck terminating.

If the nfs server is unreachable umount should have -l and/or -f? Here is a kubelet.log http://paste.fedoraproject.org/378985/46591229/ I stop seeing syncloop after a while

--- Additional comment from Wang Haoran on 2016-06-14 22:20:53 EDT ---

(In reply to hchen from comment #1)
> when the nfs server is down, unmount will hang till timeout. It probably
> takes a while (300 seconds) till timeout happens.

Hi, do you have a pr to resolve this , as you changed the status to modified ?

--- Additional comment from  on 2016-06-15 16:08:50 EDT ---

opened an upstream issue https://github.com/kubernetes/kubernetes/issues/27463

--- Additional comment from  on 2016-06-16 08:29:55 EDT ---

fixed by upstream PR https://github.com/kubernetes/kubernetes/pull/26801

--- Additional comment from Troy Dawson on 2016-07-22 15:55:11 EDT ---

This has been merged and is in OSE v3.3.0.9 or newer.

--- Additional comment from Wenqi He on 2016-07-25 05:29:14 EDT ---

I have tested this in below version:
openshift v3.3.0.9
kubernetes v1.3.0+57fb9ac
etcd 2.3.0+git

The pod of mysql keeps in "Terminating" status, but I can create another pod:
[wehe@wehepc octest]$ oc get pods
NAME              READY     STATUS        RESTARTS   AGE
hello-openshift   1/1       Running       0          8m
mysql-1-dfotg     0/1       Terminating   0          49m

on the node, check the mounted path, after nfs server is deleted, the mount path still exist

device 172.30.98.62:/ mounted on /var/lib/origin/openshift.local.volumes/pods/755640e5-5242-11e6-a3ee-fa163e5577f0/volumes/kubernetes.io~nfs/nfs with fstype nfs4 statvers=1.1
        opts:   rw,vers=4.0,rsize=524288,wsize=524288,namlen=255,acregmin=3,acregmax=60,acdirmin=30,acdirmax=60,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.1.1.1,local_lock=none
        age:    1722

@hchen, I think this is not fully fixed because the pod of mysql can not be terminated within 300 seconds and also for the mounted path disappearing.

--- Additional comment from  on 2016-07-25 10:13:11 EDT ---

The kuberenetes fix is to allow new pod creation not blocked by dead mount. However, the dead mount path cannot be not cleaned because the nfs server is unreachable.