ompi/datatype: fix bug in darray that causes MPI/IO failures

This commit fixes errors in the lb and extent of darray datatypes. For
these datatypes the lb should be the start offset of the rank's data
in the array and the extent should be the size of the entire
datatype. In master the lb was always 0 and the extent was always to
small. This commit updates the call to opal_datatype_resize to set the
correct lb and fixes the extent calculation.

Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>

ompi/datatype/ompi_datatype_create_darray.c

@@ -1,4 +1,4 @@
-/* -*- Mode: C; c-basic-offset:4 ; -*- */
+/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
 /*
  * Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
  *                         University Research and Technology
@@ -13,6 +13,8 @@
  * Copyright (c) 2009      Sun Microsystems, Inc. All rights reserved.
  * Copyright (c) 2009      Oak Ridge National Labs.  All rights reserved.
  * Copyright (c) 2010      Cisco Systems, Inc.  All rights reserved.
+ * Copyright (c) 2016      Los Alamos National Security, LLC. All rights
+ *                         reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -169,6 +171,7 @@ int32_t ompi_datatype_create_darray(int size,
     ptrdiff_t orig_extent, *st_offsets = NULL;
     int i, start_loop, end_loop, step;
     int *coords = NULL, rc = OMPI_SUCCESS;
+    ptrdiff_t displs[2], tmp_size = 1;
 
     /* speedy corner case */
     if (ndims < 1) {
@@ -187,10 +190,13 @@ int32_t ompi_datatype_create_darray(int size,
         int tmp_rank = rank, procs = size;
 
         coords = (int *) malloc(ndims * sizeof(int));
+        displs[1] = orig_extent;
         for (i = 0 ; i < ndims ; i++) {
             procs = procs / psize_array[i];
             coords[i] = tmp_rank / procs;
             tmp_rank = tmp_rank % procs;
+            /* compute the upper bound of the datatype, including all dimensions */
+            displs[1] *= gsize_array[i];
         }
     }
 
@@ -246,7 +252,6 @@ int32_t ompi_datatype_create_darray(int size,
         lastType = *newtype;
     }
 
-
     /**
      * We need to shift the content (useful data) of the datatype, so
      * we need to force the displacement to be moved. Therefore, we
@@ -255,29 +260,26 @@ int32_t ompi_datatype_create_darray(int size,
      * new data, and insert the last_Type with the correct
      * displacement.
      */
-    {
-        ptrdiff_t displs[2], tmp_size = 1;
+    displs[0] = st_offsets[start_loop];
+    for (i = start_loop + step; i != end_loop; i += step) {
+        tmp_size *= gsize_array[i - step];
+        displs[0] += tmp_size * st_offsets[i];
+    }
+    displs[0] *= orig_extent;
 
-        displs[0] = st_offsets[start_loop];
-        displs[1] = orig_extent;
-        for (i = start_loop + step; i != end_loop; i += step) {
-            tmp_size *= gsize_array[i - step];
-            displs[0] += tmp_size * st_offsets[i];
-            displs[1] *= gsize_array[i];
-        }
-        displs[0] *= orig_extent;
-
-        *newtype = ompi_datatype_create(lastType->super.desc.used);
-        rc = ompi_datatype_add(*newtype, lastType, 1, displs[0], displs[1]);
-        ompi_datatype_destroy(&lastType);
-        opal_datatype_resize( &(*newtype)->super, 0, displs[1] );
-        /* need to destroy the old type even in error condition, so
-           don't check return code from above until after cleanup. */
-        if (MPI_SUCCESS != rc) newtype = NULL;
+    *newtype = ompi_datatype_create(lastType->super.desc.used);
+    rc = ompi_datatype_add(*newtype, lastType, 1, displs[0], displs[1]);
+    ompi_datatype_destroy(&lastType);
+    /* need to destroy the old type even in error condition, so
+       don't check return code from above until after cleanup. */
+    if (MPI_SUCCESS != rc) {
+        ompi_datatype_destroy (newtype);
+    } else {
+        (void) opal_datatype_resize( &(*newtype)->super, 0, displs[1]);
     }
 
  cleanup:
-    if (NULL != st_offsets) free(st_offsets);
-    if (NULL != coords) free(coords);
-    return OMPI_SUCCESS;
+    free(st_offsets);
+    free(coords);
+    return rc;
 }