cephfs: safeguard localClusterState struct from race conditions

Multiple go-routines may simultaneously check for a clusterID's
presence in clusterAdditionalInfo and create an entry if it is
absent. This set of operation needs to be serialized.

Therefore, this commit safeguards clusterAdditionalInfo map
from concurrent writes with a mutex to prevent the above problem.

Signed-off-by: Rakshith R <[email protected]>

internal/cephfs/core/volume.go

@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"path"
 	"strings"
+	"sync"
 
 	cerrors "github.com/ceph/ceph-csi/internal/cephfs/errors"
 	fsutil "github.com/ceph/ceph-csi/internal/cephfs/util"
@@ -32,12 +33,17 @@ import (
 	"github.com/ceph/go-ceph/rados"
 )
 
-// clusterAdditionalInfo contains information regarding if resize is
-// supported in the particular cluster and subvolumegroup is
-// created or not.
-// Subvolumegroup creation and volume resize decisions are
-// taken through this additional cluster information.
-var clusterAdditionalInfo = make(map[string]*localClusterState)
+var (
+	// clusterAdditionalInfo contains information regarding if resize is
+	// supported in the particular cluster and subvolumegroup is
+	// created or not.
+	// Subvolumegroup creation and volume resize decisions are
+	// taken through this additional cluster information.
+	clusterAdditionalInfo = make(map[string]*localClusterState)
+	// clusterAdditionalInfoMutex is used to protect against
+	// concurrent writes.
+	clusterAdditionalInfoMutex = sync.Mutex{}
+)
 
 // Subvolume holds subvolume information. This includes only the needed members
 // from fsAdmin.SubVolumeInfo.
@@ -214,6 +220,8 @@ type localClusterState struct {
 func newLocalClusterState(clusterID string) {
 	// verify if corresponding clusterID key is present in the map,
 	// and if not, initialize with default values(false).
+	clusterAdditionalInfoMutex.Lock()
+	defer clusterAdditionalInfoMutex.Unlock()
 	if _, keyPresent := clusterAdditionalInfo[clusterID]; !keyPresent {
 		clusterAdditionalInfo[clusterID] = &localClusterState{}
 		clusterAdditionalInfo[clusterID].subVolumeGroupsCreated = make(map[string]bool)