[TS-1223]<fix>(mnode): check vnode dnodes num when create db and alter

db replica

src/mnode/inc/mnodeDnode.h

@@ -66,6 +66,7 @@ void    mnodeCleanupDnodes();
 
 int32_t mnodeGetDnodesNum();
 int32_t mnodeGetOnlinDnodesCpuCoreNum();
+int32_t mnodeGetVnodeDnodesNum();
 int32_t mnodeGetOnlineDnodesNum();
 void    mnodeGetOnlineAndTotalDnodesNum(int32_t *onlineNum, int32_t *totalNum);
 void *  mnodeGetNextDnode(void *pIter, SDnodeObj **pDnode);

src/mnode/src/mnodeDb.c

@@ -339,8 +339,8 @@ static int32_t mnodeCheckDbCfg(SDbCfg *pCfg) {
     return TSDB_CODE_MND_INVALID_DB_OPTION;
   }
 
-  if (pCfg->replications > mnodeGetDnodesNum()) {
-    mError("no enough dnode to config replica: %d, #dnodes: %d", pCfg->replications, mnodeGetDnodesNum());
+  if (pCfg->replications > mnodeGetVnodeDnodesNum()) {
+    mError("no enough dnode to config replica: %d, #dnodes: %d", pCfg->replications, mnodeGetVnodeDnodesNum());
     return TSDB_CODE_MND_INVALID_DB_OPTION;
   }
 
@@ -1057,7 +1057,7 @@ static SDbCfg mnodeGetAlterDbOption(SDbObj *pDb, SAlterDbMsg *pAlter) {
       terrno = TSDB_CODE_MND_INVALID_DB_OPTION;
     }
 
-    if (replications > mnodeGetDnodesNum()) {
+    if (replications > mnodeGetVnodeDnodesNum()) {
       mError("db:%s, no enough dnode to change replica:%d", pDb->name, replications);
       terrno = TSDB_CODE_MND_NO_ENOUGH_DNODES;
     }

src/mnode/src/mnodeDnode.c

@@ -271,6 +271,21 @@ int32_t mnodeGetOnlineDnodesNum() {
   return onlineDnodes;
 }
 
+int32_t mnodeGetVnodeDnodesNum() {
+  SDnodeObj *pDnode = NULL;
+  void *     pIter = NULL;
+  int32_t    numOfDnodes = 0;
+
+  while (1) {
+    pIter = mnodeGetNextDnode(pIter, &pDnode);
+    if (pDnode == NULL) break;
+    if (pDnode->alternativeRole != TAOS_DN_ALTERNATIVE_ROLE_MNODE) numOfDnodes++;
+    mnodeDecDnodeRef(pDnode);
+  }
+
+  return numOfDnodes;
+}
+
 void mnodeGetOnlineAndTotalDnodesNum(int32_t *onlineNum, int32_t *totalNum) {
   SDnodeObj *pDnode = NULL;
   void *     pIter = NULL;