Bug 2005937

Description of problem (please be detailed as possible and provide log
snippests):

Use case: to allow OCS pods to run on the worker nodes which have some non-OCS taints. 

OCS panics when trying to add tolerations for `mds` component in the StorageCluster.yaml to allow OCS pods to run on the worker nodes which have some non-OCS taints. 

For example: Below spec is added to StorageCluster yaml

```
placement:
    all:
      tolerations:
      - effect: NoSchedule
        key: xyz
        operator: Equal
        value: "true"
    mds:
      tolerations:
      - effect: NoSchedule
        key: xyz
        operator: Equal
        value: "true"
```


This is causing nil pointer exception while ensuring CephFileSystem in ocs (https://github.com/red-hat-storage/ocs-operator/blob/32158124bba496f625d6c2f01c31affde8713fa7/controllers/storagecluster/placement.go#L66) 


Error:

```
{"level":"info","ts":1631864507.7231574,"logger":"controllers.StorageCluster","msg":"Adding topology label from Node.","Request.Namespace":"openshift-storage","Request.Name":"ocs-storagecluster","Node":"ip-10-0-175-201.ec2.internal","Label":"failure-domain.beta.kubernetes.io/zone","Value":"us-east-1c"}
{"level":"info","ts":1631864507.7231665,"logger":"controllers.StorageCluster","msg":"Adding topology label from Node.","Request.Namespace":"openshift-storage","Request.Name":"ocs-storagecluster","Node":"ip-10-0-139-228.ec2.internal","Label":"failure-domain.beta.kubernetes.io/zone","Value":"us-east-1a"}
{"level":"info","ts":1631864507.7235525,"logger":"controllers.StorageCluster","msg":"Restoring original CephBlockPool.","Request.Namespace":"openshift-storage","Request.Name":"ocs-storagecluster","CephBlockPool":"openshift-storage/ocs-storagecluster-cephblockpool"}
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0x163b1b9]

goroutine 1200 [running]:
github.com/openshift/ocs-operator/controllers/storagecluster.getPlacement(0xc000877180, 0x1a76153, 0x3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/remote-source/app/controllers/storagecluster/placement.go:66 +0x299
github.com/openshift/ocs-operator/controllers/storagecluster.(*StorageClusterReconciler).newCephFilesystemInstances(0xc0005ee3c0, 0xc000877180, 0xc00012a008, 0x1ce8cc0, 0xc000401680, 0x0, 0x0)
	/remote-source/app/controllers/storagecluster/cephfilesystem.go:42 +0x1fd
github.com/openshift/ocs-operator/controllers/storagecluster.(*ocsCephFilesystems).ensureCreated(0x283e6d0, 0xc0005ee3c0, 0xc000877180, 0x0, 0x0)
	/remote-source/app/controllers/storagecluster/cephfilesystem.go:68 +0x85
github.com/openshift/ocs-operator/controllers/storagecluster.(*StorageClusterReconciler).reconcilePhases(0xc0005ee3c0, 0xc000877180, 0xc000fcf6c8, 0x11, 0xc000fcf6b0, 0x12, 0x0, 0x0, 0xc000877180, 0x0)
	/remote-source/app/controllers/storagecluster/reconcile.go:375 +0xc7f
github.com/openshift/ocs-operator/controllers/storagecluster.(*StorageClusterReconciler).Reconcile(0xc0005ee3c0, 0x1cc58d8, 0xc002414030, 0xc000fcf6c8, 0x11, 0xc000fcf6b0, 0x12, 0xc002414000, 0x0, 0x0, ...)
	/remote-source/app/controllers/storagecluster/reconcile.go:160 +0x6c5
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler(0xc000178d20, 0x1cc5830, 0xc000d37900, 0x18d32c0, 0xc000af77a0)
	/remote-source/app/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:298 +0x30d
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem(0xc000178d20, 0x1cc5830, 0xc000d37900, 0xc000a75f00)
	/remote-source/app/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:253 +0x205
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2(0xc0002bd090, 0xc000178d20, 0x1cc5830, 0xc000d37900)
	/remote-source/app/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:214 +0x6b
created by sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2
	/remote-source/app/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:210 +0x425

```



Version of all relevant components (if applicable):


Does this issue impact your ability to continue to work with the product
(please explain in detail what is the user impact)?


Is there any workaround available to the best of your knowledge?


Rate from 1 - 5 the complexity of the scenario you performed that caused this
bug (1 - very simple, 5 - very complex)?


Can this issue reproducible?


Can this issue reproduce from the UI?


If this is a regression, please provide more details to justify this:


Steps to Reproduce:
1. Setup OCS/ODF cluster 
2. Add some non OCS taints to the nodes.
3. Update StorageCluster.yaml to add toleration for taints added in step 2
4. For example:
 ```
   placement:
    all:
      tolerations:
      - effect: NoSchedule
        key: xyz
        operator: Equal
        value: "true"
    mds:
      tolerations:
      - effect: NoSchedule
        key: xyz
        operator: Equal
        value: "true"
  ```



Actual results: OCS panics and does not pass this toleration to the ceph filesystem resource and mds pods remain in pending state.


Expected results: OCS should update the ceph filesystem resource with correct toleration


Additional info: check BZ - https://bugzilla.redhat.com/show_bug.cgi?id=1992472 for more additional information.