cleanup: refactor deeply nested if statements in internal/rbd

Refactored deeply nested if statement in internal/rbd to
reduce cognitive complexity.

Signed-off-by: Rakshith R <rar@redhat.com>

internal/rbd/clone.go

@@ -74,7 +74,8 @@ func (rv *rbdVolume) checkCloneImage(ctx context.Context, parentVol *rbdVolume)
 
 	err = tempClone.checkSnapExists(snap)
 	if err != nil {
-		if errors.Is(err, ErrSnapNotFound) {
+		switch {
+		case errors.Is(err, ErrSnapNotFound):
 			// check temporary image needs flatten, if yes add task to flatten the
 			// temporary clone
 			err = tempClone.flattenRbdImage(ctx, rv.conn.Creds, false, rbdHardMaxCloneDepth, rbdSoftMaxCloneDepth)
@@ -88,7 +89,7 @@ func (rv *rbdVolume) checkCloneImage(ctx context.Context, parentVol *rbdVolume)
 				return false, err
 			}
 			return true, nil
-		} else if !errors.Is(err, ErrImageNotFound) {
+		case !errors.Is(err, ErrImageNotFound):
 			// any error other than image not found return error
 			return false, err
 		}

internal/rbd/controllerserver.go

@@ -809,7 +809,8 @@ func (cs *ControllerServer) CreateSnapshot(ctx context.Context, req *csi.CreateS
 		defer vol.Destroy()
 
 		err = vol.flattenRbdImage(ctx, cr, false, rbdHardMaxCloneDepth, rbdSoftMaxCloneDepth)
-		if errors.Is(err, ErrFlattenInProgress) {
+		switch {
+		case errors.Is(err, ErrFlattenInProgress):
 			return &csi.CreateSnapshotResponse{
 				Snapshot: &csi.Snapshot{
 					SizeBytes:      rbdSnap.SizeBytes,
@@ -819,15 +820,13 @@ func (cs *ControllerServer) CreateSnapshot(ctx context.Context, req *csi.CreateS
 					ReadyToUse:     false,
 				},
 			}, nil
-		}
+		case err != nil:
-		if err != nil {
 			uErr := undoSnapshotCloning(ctx, vol, rbdSnap, vol, cr)
 			if uErr != nil {
 				util.WarningLog(ctx, "failed undoing reservation of snapshot: %s %v", req.GetName(), uErr)
 			}
 			return nil, status.Errorf(codes.Internal, err.Error())
-		}
+		default:
-
 			return &csi.CreateSnapshotResponse{
 				Snapshot: &csi.Snapshot{
 					SizeBytes:      rbdSnap.SizeBytes,
@@ -838,6 +837,7 @@ func (cs *ControllerServer) CreateSnapshot(ctx context.Context, req *csi.CreateS
 				},
 			}, nil
 		}
+	}
 
 	err = flattenTemporaryClonedImages(ctx, rbdVol, cr)
 	if err != nil {

internal/rbd/nodeserver.go

@@ -267,8 +267,7 @@ func (ns *NodeServer) stageTransaction(ctx context.Context, req *csi.NodeStageVo
 			return transaction, err
 		}
 	}
-	if !util.CheckKernelSupport(kernelRelease, deepFlattenSupport) {
+	if !util.CheckKernelSupport(kernelRelease, deepFlattenSupport) && !skipForceFlatten {
-		if !skipForceFlatten {
 		feature, err = volOptions.checkImageChainHasFeature(ctx, librbd.FeatureDeepFlatten)
 		if err != nil {
 			return transaction, err
@@ -280,7 +279,6 @@ func (ns *NodeServer) stageTransaction(ctx context.Context, req *csi.NodeStageVo
 			}
 		}
 	}
-	}
 	// Mapping RBD image
 	var devicePath string
 	devicePath, err = attachRBDImage(ctx, volOptions, cr)
@@ -468,9 +466,10 @@ func (ns *NodeServer) mountVolumeToStagePath(ctx context.Context, req *csi.NodeS
 
 	if existingFormat == "" && !staticVol && !readOnly {
 		args := []string{}
-		if fsType == "ext4" {
+		switch fsType {
+		case "ext4":
 			args = []string{"-m0", "-Enodiscard,lazy_itable_init=1,lazy_journal_init=1", devicePath}
-		} else if fsType == "xfs" {
+		case "xfs":
 			args = []string{"-K", devicePath}
 			// always disable reflink
 			// TODO: make enabling an option, see ceph/ceph-csi#1256
@@ -531,8 +530,12 @@ func (ns *NodeServer) mountVolume(ctx context.Context, stagingPath string, req *
 func (ns *NodeServer) createTargetMountPath(ctx context.Context, mountPath string, isBlock bool) (bool, error) {
 	// Check if that mount path exists properly
 	notMnt, err := mount.IsNotMountPoint(ns.mounter, mountPath)
-	if err != nil {
+	if err == nil {
-		if os.IsNotExist(err) {
+		return notMnt, err
+	}
+	if !os.IsNotExist(err) {
+		return false, status.Error(codes.Internal, err.Error())
+	}
 	if isBlock {
 		// #nosec
 		pathFile, e := os.OpenFile(mountPath, os.O_CREATE|os.O_RDWR, 0750)
@@ -545,16 +548,12 @@ func (ns *NodeServer) createTargetMountPath(ctx context.Context, mountPath strin
 			return notMnt, status.Error(codes.Internal, err.Error())
 		}
 	} else {
-				// Create a directory
+		// Create a mountpath directory
 		if err = util.CreateMountPoint(mountPath); err != nil {
 			return notMnt, status.Error(codes.Internal, err.Error())
 		}
 	}
 	notMnt = true
-		} else {
-			return false, status.Error(codes.Internal, err.Error())
-		}
-	}
 	return notMnt, err
 }
 

internal/rbd/rbd_journal.go

@@ -277,10 +277,10 @@ func (rv *rbdVolume) Exists(ctx context.Context, parentVol *rbdVolume) (bool, er
 			// Need to check cloned info here not on createvolume,
 			if parentVol != nil {
 				found, cErr := rv.checkCloneImage(ctx, parentVol)
-				if found && cErr == nil {
+				switch {
+				case found && cErr == nil:
 					return true, nil
-				}
+				case cErr != nil:
-				if cErr != nil {
 					return false, cErr
 				}
 			}

internal/rbd/rbd_util.go

@@ -605,7 +605,9 @@ func (rv *rbdVolume) flattenRbdImage(ctx context.Context, cr *util.Credentials,
 		util.ExtendedLog(ctx, "clone depth is (%d), configured softlimit (%d) and hardlimit (%d) for %s", depth, softlimit, hardlimit, rv)
 	}
 
-	if forceFlatten || (depth >= hardlimit) || (depth >= softlimit) {
+	if !forceFlatten && (depth < hardlimit) && (depth < softlimit) {
+		return nil
+	}
 	args := []string{"flatten", rv.String(), "--id", cr.ID, "--keyfile=" + cr.KeyFile, "-m", rv.Monitors}
 	supported, err := addRbdManagerTask(ctx, rv, args)
 	if supported {
@@ -636,7 +638,7 @@ func (rv *rbdVolume) flattenRbdImage(ctx context.Context, cr *util.Credentials,
 			}
 		}
 	}
-	}
+
 	return nil
 }