Remove redundant pool parameter from snapshot class

The SnapshotClass for RBD requires a pool parameter. This is redundant
as a snapshot is not created on a different pool than the source image
of the snapshot (refer rbd man page).

Further, when a snapshot needs to be created its source CSI VolumeID
is passed to the creation call, and hence the source volumes pool
needs to be reused to create the snapshot.

Similarly to clone a snapshot, the create request would come in with a
SnapshotID to help identify the snapshot pool, and the same create
request parameters would contain the storage class based pool parameter
to create the clone into (as clones can be in different pools as
compared to their parent snapshots).

Thus, the parameter pool seems redundant in the snapshot class and
should be removed to improve ease of use.

Fixes #379

Signed-off-by: ShyamsundarR <srangana@redhat.com>

examples/README.md

@@ -73,7 +73,7 @@ In the `examples/rbd` directory you will find two files related to snapshots:
 [snapshot.yaml](./rbd/snapshot.yaml).
 
 Once you created your RBD volume, you'll need to customize at least
-`snapshotclass.yaml` and make sure the `clusterid` and `pool` parameters match
+`snapshotclass.yaml` and make sure the `clusterid` parameter matches
 your Ceph cluster setup.
 If you followed the documentation to create the rbdplugin, you shouldn't
 have to edit any other file.

examples/rbd/snapshotclass.yaml

@@ -14,7 +14,5 @@ parameters:
   # represent the Ceph cluster in clusterID below
   clusterID: <cluster-id>
 
-  pool: rbd
-
   csi.storage.k8s.io/snapshotter-secret-name: csi-rbd-secret
   csi.storage.k8s.io/snapshotter-secret-namespace: default

pkg/rbd/rbd_util.go

@@ -477,16 +477,10 @@ func getCredsFromVol(rbdVol *rbdVolume, volOptions map[string]string) {
 }
 
 func genSnapFromOptions(rbdVol *rbdVolume, snapOptions map[string]string) *rbdSnapshot {
-	var (
-		err error
-		ok  bool
-	)
+	var err error
 
 	rbdSnap := &rbdSnapshot{}
-	rbdSnap.Pool, ok = snapOptions["pool"]
-	if !ok {
-		rbdSnap.Pool = rbdVol.Pool
-	}
+	rbdSnap.Pool = rbdVol.Pool
 
 	rbdSnap.Monitors, rbdSnap.ClusterID, err = getMonsAndClusterID(snapOptions)
 	if err != nil {