[TD-4895]<fix>: more checking for creating mnode

src/balance/src/bnMain.c

@@ -637,6 +637,19 @@ int32_t bnDropDnode(SDnodeObj *pDnode) {
   return TSDB_CODE_SUCCESS;
 }
 
+int32_t bnDnodeCanCreateMnode(struct SDnodeObj *pDnode) {
+  if (pDnode == NULL)
+    return 0;
+
+  if (pDnode->isMgmt || pDnode->alternativeRole == TAOS_DN_ALTERNATIVE_ROLE_VNODE
+      || pDnode->status == TAOS_DN_STATUS_DROPPING
+      || pDnode->status == TAOS_DN_STATUS_OFFLINE) {
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
 static void bnMonitorDnodeModule() {
   int32_t numOfMnodes = mnodeGetMnodesNum();
   if (numOfMnodes >= tsNumOfMnodes) return;
@@ -645,13 +658,7 @@ static void bnMonitorDnodeModule() {
     SDnodeObj *pDnode = tsBnDnodes.list[i];
     if (pDnode == NULL) break;
 
-    if (pDnode->isMgmt || pDnode->status == TAOS_DN_STATUS_DROPPING || pDnode->status == TAOS_DN_STATUS_OFFLINE) {
-      continue;
-    }
-
-    if (pDnode->alternativeRole == TAOS_DN_ALTERNATIVE_ROLE_VNODE) {
-      continue;
-    }
+    if (!bnDnodeCanCreateMnode(pDnode)) continue;
 
     mLInfo("dnode:%d, numOfMnodes:%d expect:%d, create mnode in this dnode", pDnode->dnodeId, numOfMnodes, tsNumOfMnodes);
     mnodeCreateMnode(pDnode->dnodeId, pDnode->dnodeEp, true);

src/inc/tbn.h

@@ -31,6 +31,7 @@ void    bnReset();
 int32_t bnAllocVnodes(struct SVgObj *pVgroup);
 int32_t bnAlterDnode(struct SDnodeObj *pDnode, int32_t vnodeId, int32_t dnodeId);
 int32_t bnDropDnode(struct SDnodeObj *pDnode);
+int32_t bnDnodeCanCreateMnode(struct SDnodeObj *pDnode);
 
 #ifdef __cplusplus
 }

src/mnode/src/mnodeDnode.c

@@ -16,7 +16,6 @@
 #define _DEFAULT_SOURCE
 #include "os.h"
 #include "tgrant.h"
-#include "tbn.h"
 #include "tglobal.h"
 #include "tconfig.h"
 #include "tutil.h"
@@ -632,7 +631,8 @@ static int32_t mnodeProcessDnodeStatusMsg(SMnodeMsg *pMsg) {
   }
 
   int32_t numOfMnodes = mnodeGetMnodesNum();
-  if (numOfMnodes < tsNumOfMnodes && numOfMnodes < mnodeGetOnlineDnodesNum() && !pDnode->isMgmt) {
+  if (numOfMnodes < tsNumOfMnodes && numOfMnodes < mnodeGetOnlineDnodesNum()
+      && bnDnodeCanCreateMnode(pDnode)) {
     bnNotify();
   }