Observed the issue in OCP4.6 - OCS4.5 cluster. So this has to be fixed in OCS4.5 as well.

We still have time to fix this in 4.5z because we can only hit it with OCP4.6

Fix is avaialbe in the build 4.5.1-115.ci, however build is not available at errata but QE can start the testing.

Tested in version:

$ oc -n openshift-storage get csv
NAME                         DISPLAY                       VERSION        REPLACES              PHASE
ocs-operator.v4.5.1-594.ci   OpenShift Container Storage   4.5.1-594.ci   ocs-operator.v4.5.0   Succeeded

$ oc get clusterversion
NAME      VERSION      AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.6.0-rc.2   True        False         3h6m    Cluster version is 4.6.0-rc.2

# ceph version
ceph version 14.2.8-91.el8cp (75b4845da7d469665bd48d1a49badcc3677bf5cd) nautilus (stable)


$ oc describe pod csi-rbdplugin-provisioner-7fc6f7bf87-2vw4l -n openshift-storage|grep  Image
    Image:         quay.io/rhceph-dev/ose-csi-external-provisioner@sha256:8a6c3a0bd6f2de58b632dbde2dd0847a8ce15ce0429a8bb9a3d5787ef38c1ea2
    Image ID:      quay.io/rhceph-dev/ose-csi-external-provisioner@sha256:46f51a9ccd4cf6d8543f2167fabffc34d15834ea8f023ed91eebbdbf3bfb3635
    Image:         quay.io/rhceph-dev/ose-csi-external-resizer@sha256:50db03c10e55f2f439ce910037ee874c9285157761b0d6b3d078d3349fa6bde3
    Image ID:      quay.io/rhceph-dev/ose-csi-external-resizer@sha256:1b0b15c0edf1aa3e2098b2230752b977c734b08514a1aa074fd3b5cff00b92d2
    Image:         quay.io/rhceph-dev/ose-csi-external-attacher@sha256:a13c104ea13944963e4ca94ae6d413a428cfd6a6d6938917a8deeb16d3c3f073
    Image ID:      quay.io/rhceph-dev/ose-csi-external-attacher@sha256:72e8623ee661e5120c225d7bf2c5716a74e391fee0c9cc2bd2a0e9b685d7163d
    Image:         quay.io/rhceph-dev/cephcsi@sha256:c5ab6ca51a15066b2bdb1e9cc79afd071014147f01858f73b804750dc2376a79
    Image ID:      quay.io/rhceph-dev/cephcsi@sha256:795bcc3f751015e78314d7f894d8812cb49f49ff2c20d83328154fc641d0ee73
    Image:         quay.io/rhceph-dev/cephcsi@sha256:c5ab6ca51a15066b2bdb1e9cc79afd071014147f01858f73b804750dc2376a79
    Image ID:      quay.io/rhceph-dev/cephcsi@sha256:795bcc3f751015e78314d7f894d8812cb49f49ff2c20d83328154fc641d0ee73




The cluster was deployed with OCS 4.5 and OCP 4.5 GA versions and then upgraded to OCS 4.5.1 and OCP 4.6.
Expansion of rbd FileSystem volume mode PVC succeeded and the change is reflected on the pod.

Faced this issue with rbd Block volume mode PVC . https://bugzilla.redhat.com/show_bug.cgi?id=1887556

Verified in version:

OCS operator	v4.5.1-600.ci
Cluster Version	4.6.0-0.nightly-2020-10-13-064047
Ceph Version	14.2.8-91.el8cp
rook_csi_ceph	cephcsi@sha256:00100822dbcdbc86286bdde8be6a459c698abd5c22d335bc121185f0a59a5b44
rook_csi_resizer	ose-csi-external-resizer@sha256:50db03c10e55f2f439ce910037ee874c9285157761b0d6b3d078d3349fa6bde3

Test cases passed:
tests/manage/pv_services/pvc_resize/test_pvc_expansion.py::TestPvcExpand::test_pvc_expansion
tests/manage/pv_services/pvc_resize/test_pvc_expansion.py::TestPvcExpand::test_pvc_expand_expanded_pvc

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (OCS 4.5.1 Container Image bug fix update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:4302