fix coverity scan problem

source/dnode/mnode/impl/inc/mndDef.h

@@ -392,7 +392,7 @@ typedef struct {
 } SSmaObj;
 
 typedef struct {
-  char    name[TSDB_TABLE_FNAME_LEN];
+  char    name[TSDB_INDEX_FNAME_LEN];
   char    stb[TSDB_TABLE_FNAME_LEN];
   char    db[TSDB_DB_FNAME_LEN];
   char    dstTbName[TSDB_TABLE_FNAME_LEN];

source/dnode/mnode/impl/src/mndIndex.c

@@ -138,7 +138,7 @@ static void *mndBuildDropIdxReq(SMnode *pMnode, SVgObj *pVgroup, SStbObj *pStbOb
   mInfo("idx: %s start to build drop index req", pIdx->name);
 
   len = tSerializeSDropIdxReq(NULL, 0, &req);
-  if (ret < 0) {
+  if (len < 0) {
     goto _err;
   }
 
@@ -672,7 +672,7 @@ _OVER:
 static int32_t mndAddIndex(SMnode *pMnode, SRpcMsg *pReq, SCreateTagIndexReq *req, SDbObj *pDb, SStbObj *pStb) {
   int32_t code = -1;
   SIdxObj idxObj = {0};
-  memcpy(idxObj.name, req->idxName, TSDB_TABLE_FNAME_LEN);
+  memcpy(idxObj.name, req->idxName, TSDB_INDEX_FNAME_LEN);
   memcpy(idxObj.stb, pStb->name, TSDB_TABLE_FNAME_LEN);
   memcpy(idxObj.db, pDb->name, TSDB_DB_FNAME_LEN);
   memcpy(idxObj.colName, req->colName, TSDB_COL_NAME_LEN);

source/libs/index/src/indexFstFile.c

@@ -127,8 +127,6 @@ static int idxFileCtxDoReadFrom(IFileCtx* ctx, uint8_t* buf, int len, int32_t of
         blk->blockId = blkId;
         blk->nread = taosPReadFile(ctx->file.pFile, blk->buf, kBlockSize, blkId * kBlockSize);
         ASSERTS(blk->nread <= kBlockSize, "index read incomplete data");
-        if (blk->nread > kBlockSize) break;
-
         if (blk->nread < kBlockSize && blk->nread < len) {
           taosMemoryFree(blk);
           break;