[svn-r4396] Purpose:

bug fix
Description:
    H5FD_mpio_flush() would try to file seek negative if the
    file->eoa is 0 (e.g., doing mpio on the raw-file of the
    split file driver).  Put in a code to catch this case
    by returning succeed immediately.
Platforms tested:
    modi4(pp)

src/H5FDmpio.c

@@ -1542,6 +1542,9 @@ H5FD_mpio_flush(H5FD_t *_file)
      * Unfortunately, keeping track of EOF is an expensive operation, so
      * we can't just check whether EOF<EOA like with other drivers.
      * Therefore we'll just read the byte at EOA-1 and then write it back. */
+    /* But if eoa is zero, then nothing to flush.  Just return */
+    if (file->eoa == 0)
+	HRETURN(SUCCEED);
     if (haddr_to_MPIOff(file->eoa-1, &mpi_off)<0) {
         HRETURN_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL,
                       "cannot convert from haddr_t to MPI_Offset");