if( iBlk!=iLastBlk ){
          fsBlockNext(pFS, iBlk, &iBlk);
        }else{
          iBlk = 0;
        }
      }

      if( bExtra && (pSeg->iLastPg % nPagePerBlock)==0 ){
        fsBlockNext(pFS, iLastBlk, &iBlk);
        aUsed[iBlk-1] = 1;
      }
    }
  }
}

................................................................................
** out-of-range block numbers.
**
** If no errors are found, non-zero is returned. If an error is found, an
** assert() fails.
*/
int lsmFsIntegrityCheck(lsm_db *pDb){
  FileSystem *pFS = pDb->pFS;
  if( pFS->pCompress==0 ){
    int i;
    int j;
    Freelist freelist = {0, 0, 0};
    u8 *aUsed;
    Level *pLevel;
    Snapshot *pWorker = pDb->pWorker;
    int nBlock = pWorker->nBlock;

    aUsed = lsmMallocZero(pDb->pEnv, nBlock);
    if( aUsed==0 ){
      /* Malloc has failed. Since this function is only called within debug
       ** builds, this probably means the user is running an OOM injection test.
       ** Regardless, it will not be possible to run the integrity-check at this
       ** time, so assume the database is Ok and return non-zero. */
      return 1;
    }

    for(pLevel=pWorker->pLevel; pLevel; pLevel=pLevel->pNext){
      int i;
      checkBlocks(pFS, &pLevel->lhs, (pLevel->nRight!=0), nBlock, aUsed);
      for(i=0; i<pLevel->nRight; i++){
        checkBlocks(pFS, &pLevel->aRhs[i], 0, nBlock, aUsed);
      }
    }

    if( pWorker->nFreelistOvfl ){
      int rc = lsmCheckpointOverflowLoad(pDb, &freelist);
      assert( rc==LSM_OK || rc==LSM_NOMEM );
      if( rc!=LSM_OK ) return 1;
    }

    for(j=0; j<2; j++){
      Freelist *pFreelist;
      if( j==0 ) pFreelist = &pWorker->freelist;
      if( j==1 ) pFreelist = &freelist;

      for(i=0; i<pFreelist->nEntry; i++){
        u32 iBlk = pFreelist->aEntry[i].iBlk;
        assert( iBlk<=nBlock );
        assert( aUsed[iBlk-1]==0 );
        aUsed[iBlk-1] = 1;
      }
    }

    for(i=0; i<nBlock; i++) assert( aUsed[i]==1 );

    lsmFree(pDb->pEnv, aUsed);
    lsmFree(pDb->pEnv, freelist.aEntry);
  }

  return 1;
}

#ifndef NDEBUG
/*
** Return true if pPg happens to be the last page in segment pSeg. Or false

        if( iBlk!=iLastBlk ){
          fsBlockNext(pFS, iBlk, &iBlk);
        }else{
          iBlk = 0;
        }
      }

      if( pFS->pCompress==0 && bExtra && (pSeg->iLastPg % nPagePerBlock)==0 ){
        fsBlockNext(pFS, iLastBlk, &iBlk);
        aUsed[iBlk-1] = 1;
      }
    }
  }
}

................................................................................
** out-of-range block numbers.
**
** If no errors are found, non-zero is returned. If an error is found, an
** assert() fails.
*/
int lsmFsIntegrityCheck(lsm_db *pDb){
  FileSystem *pFS = pDb->pFS;

  int i;
  int j;
  Freelist freelist = {0, 0, 0};
  u8 *aUsed;
  Level *pLevel;
  Snapshot *pWorker = pDb->pWorker;
  int nBlock = pWorker->nBlock;

  aUsed = lsmMallocZero(pDb->pEnv, nBlock);
  if( aUsed==0 ){
    /* Malloc has failed. Since this function is only called within debug
     ** builds, this probably means the user is running an OOM injection test.
     ** Regardless, it will not be possible to run the integrity-check at this
     ** time, so assume the database is Ok and return non-zero. */
    return 1;
  }

  for(pLevel=pWorker->pLevel; pLevel; pLevel=pLevel->pNext){
    int i;
    checkBlocks(pFS, &pLevel->lhs, (pLevel->nRight!=0), nBlock, aUsed);
    for(i=0; i<pLevel->nRight; i++){
      checkBlocks(pFS, &pLevel->aRhs[i], 0, nBlock, aUsed);
    }
  }

  if( pWorker->nFreelistOvfl ){
    int rc = lsmCheckpointOverflowLoad(pDb, &freelist);
    assert( rc==LSM_OK || rc==LSM_NOMEM );
    if( rc!=LSM_OK ) return 1;
  }

  for(j=0; j<2; j++){
    Freelist *pFreelist;
    if( j==0 ) pFreelist = &pWorker->freelist;
    if( j==1 ) pFreelist = &freelist;

    for(i=0; i<pFreelist->nEntry; i++){
      u32 iBlk = pFreelist->aEntry[i].iBlk;
      assert( iBlk<=nBlock );
      assert( aUsed[iBlk-1]==0 );
      aUsed[iBlk-1] = 1;
    }
  }

  for(i=0; i<nBlock; i++) assert( aUsed[i]==1 );

  lsmFree(pDb->pEnv, aUsed);
  lsmFree(pDb->pEnv, freelist.aEntry);


  return 1;
}

#ifndef NDEBUG
/*
** Return true if pPg happens to be the last page in segment pSeg. Or false