summaryrefslogtreecommitdiffstats
path: root/src/H5FDmpio.c
blob: 67b01f18570410bc43598d6be72fdb8eb20d44a2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://www.hdfgroup.org/licenses.               *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 * Programmer:  Robb Matzke
 *              Thursday, July 29, 1999
 *
 * Purpose:     This is the MPI-2 I/O driver.
 *
 */

#include "H5FDdrvr_module.h" /* This source code file is part of the H5FD driver module */

#include "H5private.h"   /* Generic Functions                    */
#include "H5CXprivate.h" /* API Contexts                         */
#include "H5Dprivate.h"  /* Dataset functions                    */
#include "H5Eprivate.h"  /* Error handling                       */
#include "H5Fprivate.h"  /* File access                          */
#include "H5FDprivate.h" /* File drivers                         */
#include "H5FDmpi.h"     /* MPI-based file drivers               */
#include "H5Iprivate.h"  /* IDs                                  */
#include "H5MMprivate.h" /* Memory management                    */
#include "H5Pprivate.h"  /* Property lists                       */

#ifdef H5_HAVE_PARALLEL

/*
 * The driver identification number, initialized at runtime if H5_HAVE_PARALLEL
 * is defined. This allows applications to still have the H5FD_MPIO
 * "constants" in their source code.
 */
static hid_t H5FD_MPIO_g = 0;

/* Whether to allow collective I/O operations */
/* (Can be changed by setting "HDF5_MPI_OPT_TYPES" environment variable to '0' or '1') */
hbool_t H5FD_mpi_opt_types_g = TRUE;

/* Whether the driver initialized MPI on its own */
hbool_t H5FD_mpi_self_initialized = FALSE;

/*
 * The view is set to this value
 */
static char H5FD_mpi_native_g[] = "native";

/*
 * The description of a file belonging to this driver.
 * The EOF value is only used just after the file is opened in order for the
 * library to determine whether the file is empty, truncated, or okay. The MPIO
 * driver doesn't bother to keep it updated since it's an expensive operation.
 */
typedef struct H5FD_mpio_t {
    H5FD_t   pub;       /* Public stuff, must be first                  */
    MPI_File f;         /* MPIO file handle                             */
    MPI_Comm comm;      /* MPI Communicator                             */
    MPI_Info info;      /* MPI info object                              */
    int      mpi_rank;  /* This process's rank                          */
    int      mpi_size;  /* Total number of processes                    */
    haddr_t  eof;       /* End-of-file marker                           */
    haddr_t  eoa;       /* End-of-address marker                        */
    haddr_t  last_eoa;  /* Last known end-of-address marker             */
    haddr_t  local_eof; /* Local end-of-file address for each process   */
} H5FD_mpio_t;

/* Private Prototypes */

/* Callbacks */
static herr_t  H5FD__mpio_term(void);
static H5FD_t *H5FD__mpio_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr);
static herr_t  H5FD__mpio_close(H5FD_t *_file);
static herr_t  H5FD__mpio_query(const H5FD_t *_f1, unsigned long *flags);
static haddr_t H5FD__mpio_get_eoa(const H5FD_t *_file, H5FD_mem_t type);
static herr_t  H5FD__mpio_set_eoa(H5FD_t *_file, H5FD_mem_t type, haddr_t addr);
static haddr_t H5FD__mpio_get_eof(const H5FD_t *_file, H5FD_mem_t type);
static herr_t  H5FD__mpio_get_handle(H5FD_t *_file, hid_t fapl, void **file_handle);
static herr_t  H5FD__mpio_read(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, size_t size,
                               void *buf);
static herr_t  H5FD__mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, size_t size,
                                const void *buf);
static herr_t  H5FD__mpio_flush(H5FD_t *_file, hid_t dxpl_id, hbool_t closing);
static herr_t  H5FD__mpio_truncate(H5FD_t *_file, hid_t dxpl_id, hbool_t closing);
static herr_t  H5FD__mpio_delete(const char *filename, hid_t fapl_id);
static herr_t  H5FD__mpio_ctl(H5FD_t *_file, uint64_t op_code, uint64_t flags, const void *input,
                              void **output);

/* The MPIO file driver information */
static const H5FD_class_t H5FD_mpio_g = {
    H5_VFD_MPIO,           /* value                 */
    "mpio",                /* name                  */
    HADDR_MAX,             /* maxaddr               */
    H5F_CLOSE_SEMI,        /* fc_degree             */
    H5FD__mpio_term,       /* terminate             */
    NULL,                  /* sb_size               */
    NULL,                  /* sb_encode             */
    NULL,                  /* sb_decode             */
    0,                     /* fapl_size             */
    NULL,                  /* fapl_get              */
    NULL,                  /* fapl_copy             */
    NULL,                  /* fapl_free             */
    0,                     /* dxpl_size             */
    NULL,                  /* dxpl_copy             */
    NULL,                  /* dxpl_free             */
    H5FD__mpio_open,       /* open                  */
    H5FD__mpio_close,      /* close                 */
    NULL,                  /* cmp                   */
    H5FD__mpio_query,      /* query                 */
    NULL,                  /* get_type_map          */
    NULL,                  /* alloc                 */
    NULL,                  /* free                  */
    H5FD__mpio_get_eoa,    /* get_eoa               */
    H5FD__mpio_set_eoa,    /* set_eoa               */
    H5FD__mpio_get_eof,    /* get_eof               */
    H5FD__mpio_get_handle, /* get_handle            */
    H5FD__mpio_read,       /* read                  */
    H5FD__mpio_write,      /* write                 */
    H5FD__mpio_flush,      /* flush                 */
    H5FD__mpio_truncate,   /* truncate              */
    NULL,                  /* lock                  */
    NULL,                  /* unlock                */
    H5FD__mpio_delete,     /* del                   */
    H5FD__mpio_ctl,        /* ctl                   */
    H5FD_FLMAP_DICHOTOMY   /* fl_map                */
};

#ifdef H5FDmpio_DEBUG
/* Flags to control debug actions in the MPI-IO VFD.
 * (Meant to be indexed by characters)
 *
 * These flags can be set with either (or both) the environment variable
 *      "H5FD_mpio_Debug" set to a string containing one or more characters
 *      (flags) or by setting them as a string value for the
 *      "H5F_mpio_debug_key" MPI Info key.
 *
 * Supported characters in 'H5FD_mpio_Debug' string:
 *      't' trace function entry and exit
 *      'r' show read offset and size
 *      'w' show write offset and size
 *      '0'-'9' only show output from a single MPI rank (ranks 0-9 supported)
 */
static int H5FD_mpio_debug_flags_s[256];
static int H5FD_mpio_debug_rank_s = -1;

/* Indicate if this rank should output tracing info */
#define H5FD_MPIO_TRACE_THIS_RANK(file)                                                                      \
    (H5FD_mpio_debug_rank_s < 0 || H5FD_mpio_debug_rank_s == (file)->mpi_rank)
#endif

#ifdef H5FDmpio_DEBUG

/*---------------------------------------------------------------------------
 * Function:    H5FD__mpio_parse_debug_str
 *
 * Purpose:     Parse a string for debugging flags
 *
 * Returns:     N/A
 *
 * Programmer:  Quincey Koziol
 *              Wednesday, Aug 12, 2020
 *
 *---------------------------------------------------------------------------
 */
static void
H5FD__mpio_parse_debug_str(const char *s)
{
    FUNC_ENTER_STATIC_NOERR

    /* Sanity check */
    HDassert(s);

    /* Set debug mask */
    while (*s) {
        if ((int)(*s) >= (int)'0' && (int)(*s) <= (int)'9')
            H5FD_mpio_debug_rank_s = ((int)*s) - (int)'0';
        else
            H5FD_mpio_debug_flags_s[(int)*s]++;
        s++;
    } /* end while */

    FUNC_LEAVE_NOAPI_VOID
} /* end H5FD__mpio_parse_debug_str() */
#endif /* H5FDmpio_DEBUG */

/*-------------------------------------------------------------------------
 * Function:    H5FD_mpio_init
 *
 * Purpose:     Initialize this driver by registering the driver with the
 *              library.
 *
 * Return:      Success:    The driver ID for the mpio driver
 *              Failure:    H5I_INVALID_HID
 *
 * Programmer:  Robb Matzke
 *              Thursday, August 5, 1999
 *
 *-------------------------------------------------------------------------
 */
hid_t
H5FD_mpio_init(void)
{
    static int H5FD_mpio_Debug_inited = 0;
    char *     env                    = NULL;
    hid_t      ret_value              = H5I_INVALID_HID; /* Return value */

    FUNC_ENTER_NOAPI(H5I_INVALID_HID)

    /* Register the MPI-IO VFD, if it isn't already */
    if (H5I_VFL != H5I_get_type(H5FD_MPIO_g))
        H5FD_MPIO_g = H5FD_register((const H5FD_class_t *)&H5FD_mpio_g, sizeof(H5FD_class_t), FALSE);

    /* Check if MPI driver has been loaded dynamically */
    env = HDgetenv(HDF5_DRIVER);
    if (env && !HDstrcmp(env, "mpio")) {
        int mpi_initialized = 0;

        /* Initialize MPI if not already initialized */
        if (MPI_SUCCESS != MPI_Initialized(&mpi_initialized))
            HGOTO_ERROR(H5E_VFL, H5E_UNINITIALIZED, H5I_INVALID_HID, "can't check if MPI is initialized")
        if (!mpi_initialized) {
            if (MPI_SUCCESS != MPI_Init(NULL, NULL))
                HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, H5I_INVALID_HID, "can't initialize MPI")
            H5FD_mpi_self_initialized = TRUE;
        }
    }

    if (!H5FD_mpio_Debug_inited) {
        const char *s; /* String for environment variables */

        /* Allow MPI buf-and-file-type optimizations? */
        s = HDgetenv("HDF5_MPI_OPT_TYPES");
        if (s && HDisdigit(*s))
            H5FD_mpi_opt_types_g = (0 == HDstrtol(s, NULL, 0)) ? FALSE : TRUE;

#ifdef H5FDmpio_DEBUG
        /* Clear the flag buffer */
        HDmemset(H5FD_mpio_debug_flags_s, 0, sizeof(H5FD_mpio_debug_flags_s));

        /* Retrieve MPI-IO debugging environment variable */
        s = HDgetenv("H5FD_mpio_Debug");
        if (s)
            H5FD__mpio_parse_debug_str(s);
#endif /* H5FDmpio_DEBUG */

        H5FD_mpio_Debug_inited++;
    } /* end if */

    /* Set return value */
    ret_value = H5FD_MPIO_g;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD_mpio_init() */

/*---------------------------------------------------------------------------
 * Function:    H5FD__mpio_term
 *
 * Purpose:     Shut down the VFD
 *
 * Returns:     Non-negative on success or negative on failure
 *
 * Programmer:  Quincey Koziol
 *              Friday, Jan 30, 2004
 *
 *---------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_term(void)
{
    FUNC_ENTER_STATIC_NOERR

    /* Terminate MPI if the driver initialized it */
    if (H5FD_mpi_self_initialized) {
        int mpi_finalized = 0;

        MPI_Finalized(&mpi_finalized);
        if (!mpi_finalized)
            MPI_Finalize();

        H5FD_mpi_self_initialized = FALSE;
    }

    /* Reset VFL ID */
    H5FD_MPIO_g = 0;

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5FD__mpio_term() */

/*-------------------------------------------------------------------------
 * Function:    H5Pset_fapl_mpio
 *
 * Purpose:     Store the user supplied MPIO communicator comm and info in
 *              the file access property list FAPL_ID which can then be used
 *              to create and/or open the file.  This function is available
 *              only in the parallel HDF5 library and is not collective.
 *
 *              comm is the MPI communicator to be used for file open as
 *              defined in MPI_FILE_OPEN of MPI-2. This function makes a
 *              duplicate of comm. Any modification to comm after this function
 *              call returns has no effect on the access property list.
 *
 *              info is the MPI Info object to be used for file open as
 *              defined in MPI_FILE_OPEN of MPI-2. This function makes a
 *              duplicate of info. Any modification to info after this
 *              function call returns has no effect on the access property
 *              list.
 *
 *              If fapl_id has previously set comm and info values, they
 *              will be replaced and the old communicator and Info object
 *              are freed.
 *
 * Return:      Success:    Non-negative
 *              Failure:    Negative
 *
 * Programmer:  Albert Cheng
 *              Feb 3, 1998
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Pset_fapl_mpio(hid_t fapl_id, MPI_Comm comm, MPI_Info info)
{
    H5P_genplist_t *plist; /* Property list pointer */
    herr_t          ret_value;

    FUNC_ENTER_API(FAIL)
    H5TRACE3("e", "iMcMi", fapl_id, comm, info);

    /* Check arguments */
    if (fapl_id == H5P_DEFAULT)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
    if (NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list")
    if (MPI_COMM_NULL == comm)
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "MPI_COMM_NULL is not a valid communicator")

    /* Set the MPI communicator and info object */
    if (H5P_set(plist, H5F_ACS_MPI_PARAMS_COMM_NAME, &comm) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set MPI communicator")
    if (H5P_set(plist, H5F_ACS_MPI_PARAMS_INFO_NAME, &info) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set MPI info object")

    /* duplication is done during driver setting. */
    ret_value = H5P_set_driver(plist, H5FD_MPIO, NULL, NULL);

done:
    FUNC_LEAVE_API(ret_value)
} /* H5Pset_fapl_mpio() */

/*-------------------------------------------------------------------------
 * Function:    H5Pget_fapl_mpio
 *
 * Purpose:     If the file access property list is set to the H5FD_MPIO
 *              driver then this function returns duplicates of the MPI
 *              communicator and Info object stored through the comm and
 *              info pointers.  It is the responsibility of the application
 *              to free the returned communicator and Info object.
 *
 * Return:      Success:    Non-negative with the communicator and
 *                          Info object returned through the comm and
 *                          info arguments if non-null. Since they are
 *                          duplicates of the stored objects, future
 *                          modifications to the access property list do
 *                          not affect them and it is the responsibility
 *                          of the application to free them.
 *              Failure:    Negative
 *
 * Programmer:  Robb Matzke
 *              Thursday, February 26, 1998
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Pget_fapl_mpio(hid_t fapl_id, MPI_Comm *comm /*out*/, MPI_Info *info /*out*/)
{
    H5P_genplist_t *plist;               /* Property list pointer */
    herr_t          ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE3("e", "ixx", fapl_id, comm, info);

    /* Set comm and info in case we have problems */
    if (comm)
        *comm = MPI_COMM_NULL;
    if (info)
        *info = MPI_INFO_NULL;

    /* Check arguments */
    if (NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list")
    if (H5FD_MPIO != H5P_peek_driver(plist))
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "VFL driver is not MPI-I/O")

    /* Get the MPI communicator and info object */
    if (comm)
        if (H5P_get(plist, H5F_ACS_MPI_PARAMS_COMM_NAME, comm) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get MPI communicator")
    if (info)
        if (H5P_get(plist, H5F_ACS_MPI_PARAMS_INFO_NAME, info) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get MPI info object")

done:
    /* Clean up anything duplicated on errors. The free calls will set
     * the output values to MPI_COMM|INFO_NULL.
     */
    if (ret_value != SUCCEED) {
        if (comm)
            if (H5_mpi_comm_free(comm) < 0)
                HDONE_ERROR(H5E_PLIST, H5E_CANTFREE, FAIL, "unable to free MPI communicator")
        if (info)
            if (H5_mpi_info_free(info) < 0)
                HDONE_ERROR(H5E_PLIST, H5E_CANTFREE, FAIL, "unable to free MPI info object")
    }

    FUNC_LEAVE_API(ret_value)
} /* end H5Pget_fapl_mpio() */

/*-------------------------------------------------------------------------
 * Function:    H5Pset_dxpl_mpio
 *
 * Purpose:     Set the data transfer property list DXPL_ID to use transfer
 *              mode XFER_MODE. The property list can then be used to control
 *              the I/O transfer mode during data I/O operations. The valid
 *              transfer modes are:
 *
 *              H5FD_MPIO_INDEPENDENT:
 *                  Use independent I/O access (the default).
 *
 *              H5FD_MPIO_COLLECTIVE:
 *                  Use collective I/O access.
 *
 * Return:      Success:    Non-negative
 *              Failure:    Negative
 *
 * Programmer:  Albert Cheng
 *              April 2, 1998
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Pset_dxpl_mpio(hid_t dxpl_id, H5FD_mpio_xfer_t xfer_mode)
{
    H5P_genplist_t *plist;               /* Property list pointer */
    herr_t          ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "iDt", dxpl_id, xfer_mode);

    /* Check arguments */
    if (dxpl_id == H5P_DEFAULT)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
    if (NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")
    if (H5FD_MPIO_INDEPENDENT != xfer_mode && H5FD_MPIO_COLLECTIVE != xfer_mode)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "incorrect xfer_mode")

    /* Set the transfer mode */
    if (H5P_set(plist, H5D_XFER_IO_XFER_MODE_NAME, &xfer_mode) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set value")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Pset_dxpl_mpio() */

/*-------------------------------------------------------------------------
 * Function:    H5Pget_dxpl_mpio
 *
 * Purpose:     Queries the transfer mode current set in the data transfer
 *              property list DXPL_ID. This is not collective.
 *
 * Return:      Success:    Non-negative, with the transfer mode returned
 *                          through the XFER_MODE argument if it is
 *                          non-null.
 *              Failure:    Negative
 *
 * Programmer:  Albert Cheng
 *              April 2, 1998
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Pget_dxpl_mpio(hid_t dxpl_id, H5FD_mpio_xfer_t *xfer_mode /*out*/)
{
    H5P_genplist_t *plist;               /* Property list pointer */
    herr_t          ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "ix", dxpl_id, xfer_mode);

    /* Check arguments */
    if (NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")

    /* Get the transfer mode */
    if (xfer_mode)
        if (H5P_get(plist, H5D_XFER_IO_XFER_MODE_NAME, xfer_mode) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to get value")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Pget_dxpl_mpio() */

/*-------------------------------------------------------------------------
 * Function:    H5Pset_dxpl_mpio_collective_opt
 *
 * Purpose:     To set a flag to choose linked chunk I/O or multi-chunk I/O
 *              without involving decision-making inside HDF5
 *
 * Note:        The library will do linked chunk I/O or multi-chunk I/O without
 *              involving communications for decision-making process.
 *              The library won't behave as it asks for only when we find
 *              that the low-level MPI-IO package doesn't support this.
 *
 * Return:      Success:    Non-negative
 *              Failure:    Negative
 *
 * Programmer:  Kent Yang
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Pset_dxpl_mpio_collective_opt(hid_t dxpl_id, H5FD_mpio_collective_opt_t opt_mode)
{
    H5P_genplist_t *plist;               /* Property list pointer */
    herr_t          ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "iDc", dxpl_id, opt_mode);

    /* Check arguments */
    if (dxpl_id == H5P_DEFAULT)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
    if (NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")

    /* Set the transfer mode */
    if (H5P_set(plist, H5D_XFER_MPIO_COLLECTIVE_OPT_NAME, &opt_mode) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set value")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Pset_dxpl_mpio_collective_opt() */

/*-------------------------------------------------------------------------
 * Function:    H5Pset_dxpl_mpio_chunk_opt
 *
 * Purpose:     To set a flag to choose linked chunk I/O or multi-chunk I/O
 *              without involving decision-making inside HDF5
 *
 * Note:        The library will do linked chunk I/O or multi-chunk I/O without
 *              involving communications for decision-making process.
 *              The library won't behave as it asks for only when we find
 *              that the low-level MPI-IO package doesn't support this.
 *
 * Return:      Success:    Non-negative
 *              Failure:    Negative
 *
 * Programmer:  Kent Yang
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Pset_dxpl_mpio_chunk_opt(hid_t dxpl_id, H5FD_mpio_chunk_opt_t opt_mode)
{
    H5P_genplist_t *plist;               /* Property list pointer */
    herr_t          ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "iDh", dxpl_id, opt_mode);

    /* Check arguments */
    if (dxpl_id == H5P_DEFAULT)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
    if (NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")

    /* Set the transfer mode */
    if (H5P_set(plist, H5D_XFER_MPIO_CHUNK_OPT_HARD_NAME, &opt_mode) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set value")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Pset_dxpl_mpio_chunk_opt() */

/*-------------------------------------------------------------------------
 * Function:    H5Pset_dxpl_mpio_chunk_opt_num
 *
 * Purpose:     To set a threshold for doing linked chunk IO
 *
 * Note:        If the number is greater than the threshold set by the user,
 *              the library will do linked chunk I/O; otherwise, I/O will be
 *              done for every chunk.
 *
 * Return:      Success:    Non-negative
 *              Failure:    Negative
 *
 * Programmer:  Kent Yang
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Pset_dxpl_mpio_chunk_opt_num(hid_t dxpl_id, unsigned num_chunk_per_proc)
{
    H5P_genplist_t *plist;               /* Property list pointer */
    herr_t          ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "iIu", dxpl_id, num_chunk_per_proc);

    /* Check arguments */
    if (dxpl_id == H5P_DEFAULT)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
    if (NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")

    /* Set the transfer mode */
    if (H5P_set(plist, H5D_XFER_MPIO_CHUNK_OPT_NUM_NAME, &num_chunk_per_proc) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set value")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Pset_dxpl_mpio_chunk_opt_num() */

/*-------------------------------------------------------------------------
 * Function:    H5Pset_dxpl_mpio_chunk_opt_ratio
 *
 * Purpose:     To set a threshold for doing collective I/O for each chunk
 *
 * Note:        The library will calculate the percentage of the number of
 *              process holding selections at each chunk. If that percentage
 *              of number of process in the individual chunk is greater than
 *              the threshold set by the user, the library will do collective
 *              chunk I/O for this chunk; otherwise, independent I/O will be
 *              done for this chunk.
 *
 * Return:      Success:    Non-negative
 *              Failure:    Negative
 *
 * Programmer:  Kent Yang
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Pset_dxpl_mpio_chunk_opt_ratio(hid_t dxpl_id, unsigned percent_num_proc_per_chunk)
{
    H5P_genplist_t *plist;               /* Property list pointer */
    herr_t          ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "iIu", dxpl_id, percent_num_proc_per_chunk);

    /* Check arguments */
    if (dxpl_id == H5P_DEFAULT)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
    if (NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")

    /* Set the transfer mode */
    if (H5P_set(plist, H5D_XFER_MPIO_CHUNK_OPT_RATIO_NAME, &percent_num_proc_per_chunk) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set value")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Pset_dxpl_mpio_chunk_opt_ratio() */

/*-------------------------------------------------------------------------
 * Function:    H5FD_set_mpio_atomicity
 *
 * Purpose:     Sets the atomicity mode
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Mohamad Chaarawi
 *              Feb 14, 2012
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5FD_set_mpio_atomicity(H5FD_t *_file, hbool_t flag)
{
    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
#ifdef H5FDmpio_DEBUG
    hbool_t H5FD_mpio_debug_t_flag = (H5FD_mpio_debug_flags_s[(int)'t'] && H5FD_MPIO_TRACE_THIS_RANK(file));
#endif
    int    mpi_code; /* MPI return code */
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_NOAPI_NOINIT

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Entering\n", __func__, file->mpi_rank);
#endif

    /* set atomicity value */
    if (MPI_SUCCESS != (mpi_code = MPI_File_set_atomicity(file->f, (int)(flag != FALSE))))
        HMPI_GOTO_ERROR(FAIL, "MPI_File_set_atomicity", mpi_code)

done:
#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Leaving\n", __func__, file->mpi_rank);
#endif

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD_set_mpio_atomicity() */

/*-------------------------------------------------------------------------
 * Function:    H5FD_get_mpio_atomicity
 *
 * Purpose:     Returns the atomicity mode
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Mohamad Chaarawi
 *              Feb 14, 2012
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5FD_get_mpio_atomicity(H5FD_t *_file, hbool_t *flag)
{
    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
    int          temp_flag;
#ifdef H5FDmpio_DEBUG
    hbool_t H5FD_mpio_debug_t_flag = (H5FD_mpio_debug_flags_s[(int)'t'] && H5FD_MPIO_TRACE_THIS_RANK(file));
#endif
    int    mpi_code; /* MPI return code */
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_NOAPI_NOINIT

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Entering\n", __func__, file->mpi_rank);
#endif

    /* Get atomicity value */
    if (MPI_SUCCESS != (mpi_code = MPI_File_get_atomicity(file->f, &temp_flag)))
        HMPI_GOTO_ERROR(FAIL, "MPI_File_get_atomicity", mpi_code)

    if (0 != temp_flag)
        *flag = TRUE;
    else
        *flag = FALSE;

done:
#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Leaving\n", __func__, file->mpi_rank);
#endif

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD_get_mpio_atomicity() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_open
 *
 * Purpose:     Opens a file with name NAME.  The FLAGS are a bit field with
 *              purpose similar to the second argument of open(2) and which
 *              are defined in H5Fpublic.h. The file access property list
 *              FAPL_ID contains the properties driver properties and MAXADDR
 *              is the largest address which this file will be expected to
 *              access.  This is collective.
 *
 * Return:      Success:    A new file pointer
 *              Failure:    NULL
 *
 * Programmer:  Robert Kim Yates
 *              January 30, 1998
 *
 *-------------------------------------------------------------------------
 */
static H5FD_t *
H5FD__mpio_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t H5_ATTR_UNUSED maxaddr)
{
    H5FD_mpio_t *   file = NULL;          /* VFD File struct for new file */
    H5P_genplist_t *plist;                /* Property list pointer */
    MPI_Comm        comm = MPI_COMM_NULL; /* MPI Communicator, from plist */
    MPI_Info        info = MPI_INFO_NULL; /* MPI Info, from plist */
    MPI_File        fh;                   /* MPI file handle */
    hbool_t         file_opened = FALSE;  /* Flag to indicate that the file was successfully opened */
    int             mpi_amode;            /* MPI file access flags */
    int             mpi_rank = INT_MAX;   /* MPI rank of this process */
    int             mpi_size;             /* Total number of MPI processes */
    MPI_Offset      file_size;            /* File size (of existing files) */
#ifdef H5FDmpio_DEBUG
    hbool_t H5FD_mpio_debug_t_flag = FALSE;
#endif
    int     mpi_code;         /* MPI return code */
    H5FD_t *ret_value = NULL; /* Return value */

    FUNC_ENTER_STATIC

    /* Get a pointer to the fapl */
    if (NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list")

    if (H5FD_mpi_self_initialized) {
        comm = MPI_COMM_WORLD;
    }
    else {
        /* Get the MPI communicator and info object from the property list */
        if (H5P_get(plist, H5F_ACS_MPI_PARAMS_COMM_NAME, &comm) < 0)
            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, NULL, "can't get MPI communicator")
        if (H5P_get(plist, H5F_ACS_MPI_PARAMS_INFO_NAME, &info) < 0)
            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, NULL, "can't get MPI info object")
    }

    /* Get the MPI rank of this process and the total number of processes */
    if (MPI_SUCCESS != (mpi_code = MPI_Comm_rank(comm, &mpi_rank)))
        HMPI_GOTO_ERROR(NULL, "MPI_Comm_rank failed", mpi_code)
    if (MPI_SUCCESS != (mpi_code = MPI_Comm_size(comm, &mpi_size)))
        HMPI_GOTO_ERROR(NULL, "MPI_Comm_size failed", mpi_code)

#ifdef H5FDmpio_DEBUG
    H5FD_mpio_debug_t_flag = (H5FD_mpio_debug_flags_s[(int)'t'] &&
                              (H5FD_mpio_debug_rank_s < 0 || H5FD_mpio_debug_rank_s == mpi_rank));
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Entering - name = \"%s\", flags = 0x%x, fapl_id = %d, maxaddr = %lu\n",
                  __func__, mpi_rank, name, flags, (int)fapl_id, (unsigned long)maxaddr);
#endif

    /* Convert HDF5 flags to MPI-IO flags */
    /* Some combinations are illegal; let MPI-IO figure it out */
    mpi_amode = (flags & H5F_ACC_RDWR) ? MPI_MODE_RDWR : MPI_MODE_RDONLY;
    if (flags & H5F_ACC_CREAT)
        mpi_amode |= MPI_MODE_CREATE;
    if (flags & H5F_ACC_EXCL)
        mpi_amode |= MPI_MODE_EXCL;

#ifdef H5FDmpio_DEBUG
    /* Check for debug commands in the info parameter */
    if (MPI_INFO_NULL != info) {
        char debug_str[128];
        int  flag;

        MPI_Info_get(info, H5F_MPIO_DEBUG_KEY, sizeof(debug_str) - 1, debug_str, &flag);
        if (flag)
            H5FD__mpio_parse_debug_str(debug_str);
    } /* end if */
#endif

    if (MPI_SUCCESS != (mpi_code = MPI_File_open(comm, name, mpi_amode, info, &fh)))
        HMPI_GOTO_ERROR(NULL, "MPI_File_open failed", mpi_code)
    file_opened = TRUE;

    /* Build the return value and initialize it */
    if (NULL == (file = (H5FD_mpio_t *)H5MM_calloc(sizeof(H5FD_mpio_t))))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
    file->f        = fh;
    file->comm     = comm;
    file->info     = info;
    file->mpi_rank = mpi_rank;
    file->mpi_size = mpi_size;

    /* Only processor p0 will get the filesize and broadcast it. */
    if (mpi_rank == 0)
        if (MPI_SUCCESS != (mpi_code = MPI_File_get_size(fh, &file_size)))
            HMPI_GOTO_ERROR(NULL, "MPI_File_get_size failed", mpi_code)

    /* Broadcast file size */
    if (MPI_SUCCESS != (mpi_code = MPI_Bcast(&file_size, (int)sizeof(MPI_Offset), MPI_BYTE, 0, comm)))
        HMPI_GOTO_ERROR(NULL, "MPI_Bcast failed", mpi_code)

    /* Determine if the file should be truncated */
    if (file_size && (flags & H5F_ACC_TRUNC)) {
        /* Truncate the file */
        if (MPI_SUCCESS != (mpi_code = MPI_File_set_size(fh, (MPI_Offset)0)))
            HMPI_GOTO_ERROR(NULL, "MPI_File_set_size failed", mpi_code)

        /* Don't let any proc return until all have truncated the file. */
        if (MPI_SUCCESS != (mpi_code = MPI_Barrier(comm)))
            HMPI_GOTO_ERROR(NULL, "MPI_Barrier failed", mpi_code)

        /* File is zero size now */
        file_size = 0;
    } /* end if */

    /* Set the size of the file (from library's perspective) */
    file->eof       = H5FD_mpi_MPIOff_to_haddr(file_size);
    file->local_eof = file->eof;

    /* Set return value */
    ret_value = (H5FD_t *)file;

done:
    if (ret_value == NULL) {
        if (file_opened)
            MPI_File_close(&fh);
        if (H5_mpi_comm_free(&comm) < 0)
            HDONE_ERROR(H5E_VFL, H5E_CANTFREE, NULL, "unable to free MPI communicator")
        if (H5_mpi_info_free(&info) < 0)
            HDONE_ERROR(H5E_VFL, H5E_CANTFREE, NULL, "unable to free MPI info object")
        if (file)
            H5MM_xfree(file);
    } /* end if */

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Leaving\n", __func__, mpi_rank);
#endif

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD__mpio_open() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_close
 *
 * Purpose:     Closes a file.  This is collective.
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Unknown
 *              January 30, 1998
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_close(H5FD_t *_file)
{
    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
#ifdef H5FDmpio_DEBUG
    hbool_t H5FD_mpio_debug_t_flag = (H5FD_mpio_debug_flags_s[(int)'t'] && H5FD_MPIO_TRACE_THIS_RANK(file));
    int     mpi_rank               = file->mpi_rank;
#endif
    int    mpi_code;            /* MPI return code */
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_STATIC

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Entering\n", __func__, file->mpi_rank);
#endif

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);

    /* MPI_File_close sets argument to MPI_FILE_NULL */
    if (MPI_SUCCESS != (mpi_code = MPI_File_close(&(file->f))))
        HMPI_GOTO_ERROR(FAIL, "MPI_File_close failed", mpi_code)

    /* Clean up other stuff */
    H5_mpi_comm_free(&file->comm);
    H5_mpi_info_free(&file->info);
    H5MM_xfree(file);

done:
#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Leaving\n", __func__, mpi_rank);
#endif

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD__mpio_close() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_query
 *
 * Purpose:     Set the flags that this VFL driver is capable of supporting.
 *              (listed in H5FDpublic.h)
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Quincey Koziol
 *              Friday, August 25, 2000
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_query(const H5FD_t H5_ATTR_UNUSED *_file, unsigned long *flags /* out */)
{
    FUNC_ENTER_STATIC_NOERR

    /* Set the VFL feature flags that this driver supports */
    if (flags) {
        *flags = 0;
        *flags |= H5FD_FEAT_AGGREGATE_METADATA;  /* OK to aggregate metadata allocations  */
        *flags |= H5FD_FEAT_AGGREGATE_SMALLDATA; /* OK to aggregate "small" raw data allocations */
        *flags |= H5FD_FEAT_HAS_MPI; /* This driver uses MPI                                             */
        *flags |= H5FD_FEAT_ALLOCATE_EARLY;         /* Allocate space early instead of late         */
        *flags |= H5FD_FEAT_DEFAULT_VFD_COMPATIBLE; /* VFD creates a file which can be opened with the default
                                                       VFD */
    }                                               /* end if */

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5FD__mpio_query() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_get_eoa
 *
 * Purpose:     Gets the end-of-address marker for the file. The EOA marker
 *              is the first address past the last byte allocated in the
 *              format address space.
 *
 * Return:      Success:    The end-of-address marker
 *              Failure:    HADDR_UNDEF
 *
 * Programmer:  Robb Matzke
 *              Friday, August  6, 1999
 *
 *-------------------------------------------------------------------------
 */
static haddr_t
H5FD__mpio_get_eoa(const H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type)
{
    const H5FD_mpio_t *file = (const H5FD_mpio_t *)_file;

    FUNC_ENTER_STATIC_NOERR

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);

    FUNC_LEAVE_NOAPI(file->eoa)
} /* end H5FD__mpio_get_eoa() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_set_eoa
 *
 * Purpose:     Set the end-of-address marker for the file. This function is
 *              called shortly after an existing HDF5 file is opened in order
 *              to tell the driver where the end of the HDF5 data is located.
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Robb Matzke
 *              Friday, August 6, 1999
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_set_eoa(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type, haddr_t addr)
{
    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;

    FUNC_ENTER_STATIC_NOERR

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);

    file->eoa = addr;

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5FD__mpio_set_eoa() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_get_eof
 *
 * Purpose:     Gets the end-of-file marker for the file. The EOF marker
 *              is the real size of the file.
 *
 *              The MPIO driver doesn't bother keeping this field updated
 *              since that's a relatively expensive operation. Fortunately
 *              the library only needs the EOF just after the file is opened
 *              in order to determine whether the file is empty, truncated,
 *              or okay.  Therefore, any MPIO I/O function will set its value
 *              to HADDR_UNDEF which is the error return value of this
 *              function.
 *
 *              Keeping the EOF updated (during write calls) is expensive
 *              because any process may extend the physical end of the
 *              file. -QAK
 *
 * Return:      Success:    The end-of-file marker
 *              Failure:    HADDR_UNDEF
 *
 * Programmer:  Robb Matzke
 *              Friday, August  6, 1999
 *
 *-------------------------------------------------------------------------
 */
static haddr_t
H5FD__mpio_get_eof(const H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type)
{
    const H5FD_mpio_t *file = (const H5FD_mpio_t *)_file;

    FUNC_ENTER_STATIC_NOERR

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);

    FUNC_LEAVE_NOAPI(file->eof)
} /* end H5FD__mpio_get_eof() */

/*-------------------------------------------------------------------------
 * Function:       H5FD__mpio_get_handle
 *
 * Purpose:        Returns the file handle of MPIO file driver.
 *
 * Returns:        SUCCEED/FAIL
 *
 * Programmer:     Raymond Lu
 *                 Sept. 16, 2002
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_get_handle(H5FD_t *_file, hid_t H5_ATTR_UNUSED fapl, void **file_handle)
{
    H5FD_mpio_t *file      = (H5FD_mpio_t *)_file;
    herr_t       ret_value = SUCCEED;

    FUNC_ENTER_STATIC

    if (!file_handle)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "file handle not valid")

    *file_handle = &(file->f);

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD__mpio_get_handle() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_read
 *
 * Purpose:     Reads SIZE bytes of data from FILE beginning at address ADDR
 *              into buffer BUF according to data transfer properties in
 *              DXPL_ID using potentially complex file and buffer types to
 *              effect the transfer.
 *
 *              Reading past the end of the MPI file returns zeros instead of
 *              failing.  MPI is able to coalesce requests from different
 *              processes (collective or independent).
 *
 * Return:      Success:    SUCCEED. Result is stored in caller-supplied
 *                          buffer BUF.
 *
 *              Failure:    FAIL. Contents of buffer BUF are undefined.
 *
 * Programmer:  rky, 1998-01-30
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type, hid_t H5_ATTR_UNUSED dxpl_id, haddr_t addr,
                size_t size, void *buf /*out*/)
{
    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
    MPI_Offset   mpi_off;
    MPI_Status   mpi_stat;            /* Status from I/O operation */
    MPI_Datatype buf_type = MPI_BYTE; /* MPI description of the selection in memory */
    int          size_i;              /* Integer copy of 'size' to read */
#if MPI_VERSION >= 3
    MPI_Count bytes_read = 0; /* Number of bytes read in */
    MPI_Count type_size;      /* MPI datatype used for I/O's size */
    MPI_Count io_size;        /* Actual number of bytes requested */
    MPI_Count n;
#else
    int bytes_read = 0; /* Number of bytes read in */
    int type_size;      /* MPI datatype used for I/O's size */
    int io_size;        /* Actual number of bytes requested */
    int n;
#endif
    hbool_t use_view_this_time = FALSE;
    hbool_t rank0_bcast        = FALSE; /* If read-with-rank0-and-bcast flag was used */
#ifdef H5FDmpio_DEBUG
    hbool_t H5FD_mpio_debug_t_flag = (H5FD_mpio_debug_flags_s[(int)'t'] && H5FD_MPIO_TRACE_THIS_RANK(file));
    hbool_t H5FD_mpio_debug_r_flag = (H5FD_mpio_debug_flags_s[(int)'r'] && H5FD_MPIO_TRACE_THIS_RANK(file));
#endif
    int    mpi_code; /* MPI return code */
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_STATIC

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Entering\n", __func__, file->mpi_rank);
#endif

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);
    HDassert(buf);

    /* Portably initialize MPI status variable */
    HDmemset(&mpi_stat, 0, sizeof(MPI_Status));

    /* some numeric conversions */
    if (H5FD_mpi_haddr_to_MPIOff(addr, &mpi_off /*out*/) < 0)
        HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from haddr to MPI off")
    size_i = (int)size;
    if ((hsize_t)size_i != size)
        HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from size to size_i")

    /* Only look for MPI views for raw data transfers */
    if (type == H5FD_MEM_DRAW) {
        H5FD_mpio_xfer_t xfer_mode; /* I/O transfer mode */

        /* Get the transfer mode from the API context */
        if (H5CX_get_io_xfer_mode(&xfer_mode) < 0)
            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "can't get MPI-I/O transfer mode")

        /*
         * Set up for a fancy xfer using complex types, or single byte block. We
         * wouldn't need to rely on the use_view field if MPI semantics allowed
         * us to test that btype=ftype=MPI_BYTE (or even MPI_TYPE_NULL, which
         * could mean "use MPI_BYTE" by convention).
         */
        if (xfer_mode == H5FD_MPIO_COLLECTIVE) {
            MPI_Datatype file_type;

            /* Remember that views are used */
            use_view_this_time = TRUE;

            /* Prepare for a full-blown xfer using btype, ftype, and disp */
            if (H5CX_get_mpi_coll_datatypes(&buf_type, &file_type) < 0)
                HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "can't get MPI-I/O datatypes")

            /*
             * Set the file view when we are using MPI derived types
             */
            if (MPI_SUCCESS != (mpi_code = MPI_File_set_view(file->f, mpi_off, MPI_BYTE, file_type,
                                                             H5FD_mpi_native_g, file->info)))
                HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mpi_code)

            /* When using types, use the address as the displacement for
             * MPI_File_set_view and reset the address for the read to zero
             */
            mpi_off = 0;
        } /* end if */
    }     /* end if */

    /* Read the data. */
    if (use_view_this_time) {
        H5FD_mpio_collective_opt_t coll_opt_mode;

#ifdef H5FDmpio_DEBUG
        if (H5FD_mpio_debug_r_flag)
            HDfprintf(stderr, "%s: (%d) using MPIO collective mode\n", __func__, file->mpi_rank);
#endif
        /* Get the collective_opt property to check whether the application wants to do IO individually. */
        if (H5CX_get_mpio_coll_opt(&coll_opt_mode) < 0)
            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "can't get MPI-I/O collective_op property")

        if (coll_opt_mode == H5FD_MPIO_COLLECTIVE_IO) {
#ifdef H5FDmpio_DEBUG
            if (H5FD_mpio_debug_r_flag)
                HDfprintf(stderr, "%s: (%d) doing MPI collective IO\n", __func__, file->mpi_rank);
#endif
            /* Check whether we should read from rank 0 and broadcast to other ranks */
            if (H5CX_get_mpio_rank0_bcast()) {
#ifdef H5FDmpio_DEBUG
                if (H5FD_mpio_debug_r_flag)
                    HDfprintf(stderr, "%s: (%d) doing read-rank0-and-MPI_Bcast\n", __func__, file->mpi_rank);
#endif
                /* Indicate path we've taken */
                rank0_bcast = TRUE;

                /* Read on rank 0 Bcast to other ranks */
                if (file->mpi_rank == 0)
                    if (MPI_SUCCESS !=
                        (mpi_code = MPI_File_read_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
                        HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at failed", mpi_code)
                if (MPI_SUCCESS != (mpi_code = MPI_Bcast(buf, size_i, buf_type, 0, file->comm)))
                    HMPI_GOTO_ERROR(FAIL, "MPI_Bcast failed", mpi_code)
            } /* end if */
            else
                /* Perform collective read operation */
                if (MPI_SUCCESS !=
                    (mpi_code = MPI_File_read_at_all(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
                HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at_all failed", mpi_code)
        } /* end if */
        else {
#ifdef H5FDmpio_DEBUG
            if (H5FD_mpio_debug_r_flag)
                HDfprintf(stderr, "%s: (%d) doing MPI independent IO\n", __func__, file->mpi_rank);
#endif

            /* Perform independent read operation */
            if (MPI_SUCCESS !=
                (mpi_code = MPI_File_read_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
                HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at failed", mpi_code)
        } /* end else */

        /*
         * Reset the file view when we used MPI derived types
         */
        if (MPI_SUCCESS != (mpi_code = MPI_File_set_view(file->f, (MPI_Offset)0, MPI_BYTE, MPI_BYTE,
                                                         H5FD_mpi_native_g, file->info)))
            HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mpi_code)
    } /* end if */
    else {
#ifdef H5FDmpio_DEBUG
        if (H5FD_mpio_debug_r_flag)
            HDfprintf(stderr, "%s: (%d) doing MPI independent IO\n", __func__, file->mpi_rank);
#endif

        /* Perform independent read operation */
        if (MPI_SUCCESS != (mpi_code = MPI_File_read_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
            HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at failed", mpi_code)
    } /* end else */

    /* Only retrieve bytes read if this rank _actually_ participated in I/O */
    if (!rank0_bcast || (rank0_bcast && file->mpi_rank == 0)) {
        /* How many bytes were actually read? */
#if MPI_VERSION >= 3
        if (MPI_SUCCESS != (mpi_code = MPI_Get_elements_x(&mpi_stat, buf_type, &bytes_read)))
#else
        if (MPI_SUCCESS != (mpi_code = MPI_Get_elements(&mpi_stat, MPI_BYTE, &bytes_read)))
#endif
            HMPI_GOTO_ERROR(FAIL, "MPI_Get_elements failed", mpi_code)
    } /* end if */

    /* If the rank0-bcast feature was used, broadcast the # of bytes read to
     * other ranks, which didn't perform any I/O.
     */
    /* NOTE: This could be optimized further to be combined with the broadcast
     *          of the data.  (QAK - 2019/1/2)
     */
    if (rank0_bcast)
#if MPI_VERSION >= 3
        if (MPI_SUCCESS != MPI_Bcast(&bytes_read, 1, MPI_COUNT, 0, file->comm))
#else
        if (MPI_SUCCESS != MPI_Bcast(&bytes_read, 1, MPI_INT, 0, file->comm))
#endif
            HMPI_GOTO_ERROR(FAIL, "MPI_Bcast failed", 0)

            /* Get the type's size */
#if MPI_VERSION >= 3
    if (MPI_SUCCESS != (mpi_code = MPI_Type_size_x(buf_type, &type_size)))
#else
    if (MPI_SUCCESS != (mpi_code = MPI_Type_size(buf_type, &type_size)))
#endif
        HMPI_GOTO_ERROR(FAIL, "MPI_Type_size failed", mpi_code)

    /* Compute the actual number of bytes requested */
    io_size = type_size * size_i;

    /* Check for read failure */
    if (bytes_read < 0 || bytes_read > io_size)
        HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "file read failed")

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_r_flag)
        HDfprintf(stderr, "%s: (%d) mpi_off = %ld  bytes_read = %lld\n", __func__, file->mpi_rank,
                  (long)mpi_off, bytes_read);
#endif

    /*
     * This gives us zeroes beyond end of physical MPI file.
     */
    if ((n = (io_size - bytes_read)) > 0)
        HDmemset((char *)buf + bytes_read, 0, (size_t)n);

done:
#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Leaving\n", __func__, file->mpi_rank);
#endif

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD__mpio_read() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_write
 *
 * Purpose:     Writes SIZE bytes of data to FILE beginning at address ADDR
 *              from buffer BUF according to data transfer properties in
 *              DXPL_ID using potentially complex file and buffer types to
 *              effect the transfer.
 *
 *              MPI is able to coalesce requests from different processes
 *              (collective and independent).
 *
 * Return:      Success:    SUCCEED. USE_TYPES and OLD_USE_TYPES in the
 *                          access params are altered.
 *              Failure:    FAIL. USE_TYPES and OLD_USE_TYPES in the
 *                          access params may be altered.
 *
 * Programmer:  Robert Kim Yates
 *              January 30, 1998
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id, haddr_t addr, size_t size,
                 const void *buf)
{
    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
    MPI_Offset   mpi_off;
    MPI_Status   mpi_stat;            /* Status from I/O operation */
    MPI_Datatype buf_type = MPI_BYTE; /* MPI description of the selection in memory */
#if MPI_VERSION >= 3
    MPI_Count bytes_written;
    MPI_Count type_size; /* MPI datatype used for I/O's size */
    MPI_Count io_size;   /* Actual number of bytes requested */
#else
    int bytes_written;
    int type_size; /* MPI datatype used for I/O's size */
    int io_size;   /* Actual number of bytes requested */
#endif
    int              size_i;
    hbool_t          use_view_this_time = FALSE;
    hbool_t          derived_type       = FALSE;
    H5FD_mpio_xfer_t xfer_mode; /* I/O transfer mode */
#ifdef H5FDmpio_DEBUG
    hbool_t H5FD_mpio_debug_t_flag = (H5FD_mpio_debug_flags_s[(int)'t'] && H5FD_MPIO_TRACE_THIS_RANK(file));
    hbool_t H5FD_mpio_debug_w_flag = (H5FD_mpio_debug_flags_s[(int)'w'] && H5FD_MPIO_TRACE_THIS_RANK(file));
#endif
    int    mpi_code; /* MPI return code */
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_STATIC

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Entering\n", __func__, file->mpi_rank);
#endif

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);
    HDassert(buf);

    /* Verify that no data is written when between MPI_Barrier()s during file flush */
    HDassert(!H5CX_get_mpi_file_flushing());

    /* Portably initialize MPI status variable */
    HDmemset(&mpi_stat, 0, sizeof(MPI_Status));

    /* some numeric conversions */
    if (H5FD_mpi_haddr_to_MPIOff(addr, &mpi_off) < 0)
        HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from haddr to MPI off")
    size_i = (int)size;

    /* Get the transfer mode from the API context */
    if (H5CX_get_io_xfer_mode(&xfer_mode) < 0)
        HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "can't get MPI-I/O transfer mode")

    /*
     * Set up for a fancy xfer using complex types, or single byte block. We
     * wouldn't need to rely on the use_view field if MPI semantics allowed
     * us to test that btype=ftype=MPI_BYTE (or even MPI_TYPE_NULL, which
     * could mean "use MPI_BYTE" by convention).
     */
    if (xfer_mode == H5FD_MPIO_COLLECTIVE) {
        MPI_Datatype file_type;

        /* Remember that views are used */
        use_view_this_time = TRUE;

        /* Prepare for a full-blown xfer using btype, ftype, and disp */
        if (H5CX_get_mpi_coll_datatypes(&buf_type, &file_type) < 0)
            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "can't get MPI-I/O datatypes")

        /*
         * Set the file view when we are using MPI derived types
         */
        if (MPI_SUCCESS != (mpi_code = MPI_File_set_view(file->f, mpi_off, MPI_BYTE, file_type,
                                                         H5FD_mpi_native_g, file->info)))
            HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mpi_code)

        /* When using types, use the address as the displacement for
         * MPI_File_set_view and reset the address for the read to zero
         */
        mpi_off = 0;
    } /* end if */
    else if (size != (hsize_t)size_i) {
        /* If HERE, then we need to work around the integer size limit
         * of 2GB. The input size_t size variable cannot fit into an integer,
         * but we can get around that limitation by creating a different datatype
         * and then setting the integer size (or element count) to 1 when using
         * the derived_type.
         */

        if (H5_mpio_create_large_type(size, 0, MPI_BYTE, &buf_type) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "can't create MPI-I/O datatype")

        derived_type = TRUE;
        size_i       = 1;
    }

    /* Write the data. */
    if (use_view_this_time) {
        H5FD_mpio_collective_opt_t coll_opt_mode;

#ifdef H5FDmpio_DEBUG
        if (H5FD_mpio_debug_w_flag)
            HDfprintf(stderr, "%s: (%d) using MPIO collective mode\n", __func__, file->mpi_rank);
#endif

        /* Get the collective_opt property to check whether the application wants to do IO individually. */
        if (H5CX_get_mpio_coll_opt(&coll_opt_mode) < 0)
            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "can't get MPI-I/O collective_op property")

        if (coll_opt_mode == H5FD_MPIO_COLLECTIVE_IO) {
#ifdef H5FDmpio_DEBUG
            if (H5FD_mpio_debug_w_flag)
                HDfprintf(stderr, "%s: (%d) doing MPI collective IO\n", __func__, file->mpi_rank);
#endif
            /* Perform collective write operation */
            if (MPI_SUCCESS !=
                (mpi_code = MPI_File_write_at_all(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
                HMPI_GOTO_ERROR(FAIL, "MPI_File_write_at_all failed", mpi_code)
        } /* end if */
        else {
            if (type != H5FD_MEM_DRAW)
                HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL,
                            "Metadata Coll opt property should be collective at this point")

#ifdef H5FDmpio_DEBUG
            if (H5FD_mpio_debug_w_flag)
                HDfprintf(stderr, "%s: (%d) doing MPI independent IO\n", __func__, file->mpi_rank);
#endif
            /* Perform independent write operation */
            if (MPI_SUCCESS !=
                (mpi_code = MPI_File_write_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
                HMPI_GOTO_ERROR(FAIL, "MPI_File_write_at failed", mpi_code)
        } /* end else */

        /* Reset the file view when we used MPI derived types */
        if (MPI_SUCCESS != (mpi_code = MPI_File_set_view(file->f, (MPI_Offset)0, MPI_BYTE, MPI_BYTE,
                                                         H5FD_mpi_native_g, file->info)))
            HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mpi_code)
    } /* end if */
    else {
#ifdef H5FDmpio_DEBUG
        if (H5FD_mpio_debug_w_flag)
            HDfprintf(stderr, "%s: (%d) doing MPI independent IO\n", __func__, file->mpi_rank);
#endif

        /* Perform independent write operation */
        if (MPI_SUCCESS != (mpi_code = MPI_File_write_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
            HMPI_GOTO_ERROR(FAIL, "MPI_File_write_at failed", mpi_code)
    } /* end else */

    /* How many bytes were actually written? */
#if MPI_VERSION >= 3
    if (MPI_SUCCESS != (mpi_code = MPI_Get_elements_x(&mpi_stat, buf_type, &bytes_written)))
#else
    if (MPI_SUCCESS != (mpi_code = MPI_Get_elements(&mpi_stat, MPI_BYTE, &bytes_written)))
#endif
        HMPI_GOTO_ERROR(FAIL, "MPI_Get_elements failed", mpi_code)

        /* Get the type's size */
#if MPI_VERSION >= 3
    if (MPI_SUCCESS != (mpi_code = MPI_Type_size_x(buf_type, &type_size)))
#else
    if (MPI_SUCCESS != (mpi_code = MPI_Type_size(buf_type, &type_size)))
#endif
        HMPI_GOTO_ERROR(FAIL, "MPI_Type_size failed", mpi_code)

    /* Compute the actual number of bytes requested */
    io_size = type_size * size_i;

    /* Check for write failure */
    if (bytes_written != io_size || bytes_written < 0)
        HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "file write failed")

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_w_flag)
        HDfprintf(stderr, "%s: (%d) mpi_off = %ld  bytes_written = %lld\n", __func__, file->mpi_rank,
                  (long)mpi_off, bytes_written);
#endif

    /* Each process will keep track of its perceived EOF value locally, and
     * ultimately we will reduce this value to the maximum amongst all
     * processes, but until then keep the actual eof at HADDR_UNDEF just in
     * case something bad happens before that point. (rather have a value
     * we know is wrong sitting around rather than one that could only
     * potentially be wrong.) */
    file->eof = HADDR_UNDEF;

    if (bytes_written && (((haddr_t)bytes_written + addr) > file->local_eof))
        file->local_eof = addr + (haddr_t)bytes_written;

done:
    if (derived_type)
        MPI_Type_free(&buf_type);

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Leaving: ret_value = %d\n", __func__, file->mpi_rank, ret_value);
#endif

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD__mpio_write() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_flush
 *
 * Purpose:     Makes sure that all data is on disk.  This is collective.
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Robb Matzke
 *              January 30, 1998
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_flush(H5FD_t *_file, hid_t H5_ATTR_UNUSED dxpl_id, hbool_t closing)
{
    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
#ifdef H5FDmpio_DEBUG
    hbool_t H5FD_mpio_debug_t_flag = (H5FD_mpio_debug_flags_s[(int)'t'] && H5FD_MPIO_TRACE_THIS_RANK(file));
#endif
    int    mpi_code; /* mpi return code */
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_STATIC

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Entering\n", __func__, file->mpi_rank);
#endif

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);

    /* Only sync the file if we are not going to immediately close it */
    if (!closing)
        if (MPI_SUCCESS != (mpi_code = MPI_File_sync(file->f)))
            HMPI_GOTO_ERROR(FAIL, "MPI_File_sync failed", mpi_code)

done:
#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Leaving\n", __func__, file->mpi_rank);
#endif

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD__mpio_flush() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_truncate
 *
 * Purpose:     Make certain the file's size matches it's allocated size
 *
 *              This is a little sticky in the mpio case, as it is not
 *              easy for us to track the current EOF by extracting it from
 *              write calls, since other ranks could have written to the
 *              file beyond the local EOF.
 *
 *              Instead, we first check to see if the EOA has changed since
 *              the last call to this function.  If it has, we call
 *              MPI_File_get_size() to determine the current EOF, and
 *              only call MPI_File_set_size() if this value disagrees
 *              with the current EOA.
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Quincey Koziol
 *              January 31, 2008
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_truncate(H5FD_t *_file, hid_t H5_ATTR_UNUSED dxpl_id, hbool_t H5_ATTR_UNUSED closing)
{
    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
#ifdef H5FDmpio_DEBUG
    hbool_t H5FD_mpio_debug_t_flag = (H5FD_mpio_debug_flags_s[(int)'t'] && H5FD_MPIO_TRACE_THIS_RANK(file));
#endif
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_STATIC

#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Entering\n", __func__, file->mpi_rank);
#endif

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);

    if (!H5F_addr_eq(file->eoa, file->last_eoa)) {
        int        mpi_code; /* mpi return code */
        MPI_Offset size;
        MPI_Offset needed_eof;

        /* In principle, it is possible for the size returned by the
         * call to MPI_File_get_size() to depend on whether writes from
         * all proceeses have completed at the time process 0 makes the
         * call.
         *
         * In practice, most (all?) truncate calls will come after a barrier
         * and with no interviening writes to the file (with the possible
         * exception of sueprblock / superblock extension message updates).
         *
         * Check the "MPI file closing" flag in the API context to determine
         * if we can skip the barrier.
         */
        if (!H5CX_get_mpi_file_flushing())
            if (MPI_SUCCESS != (mpi_code = MPI_Barrier(file->comm)))
                HMPI_GOTO_ERROR(FAIL, "MPI_Barrier failed", mpi_code)

        /* Only processor p0 will get the filesize and broadcast it. */
        /* (Note that throwing an error here will cause non-rank 0 processes
         *      to hang in following Bcast.  -QAK, 3/17/2018)
         */
        if (0 == file->mpi_rank)
            if (MPI_SUCCESS != (mpi_code = MPI_File_get_size(file->f, &size)))
                HMPI_GOTO_ERROR(FAIL, "MPI_File_get_size failed", mpi_code)

        /* Broadcast file size */
        if (MPI_SUCCESS != (mpi_code = MPI_Bcast(&size, (int)sizeof(MPI_Offset), MPI_BYTE, 0, file->comm)))
            HMPI_GOTO_ERROR(FAIL, "MPI_Bcast failed", mpi_code)

        if (H5FD_mpi_haddr_to_MPIOff(file->eoa, &needed_eof) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "cannot convert from haddr_t to MPI_Offset")

        /* EOA != EOF.  Set EOF to EOA */
        if (size != needed_eof) {
            /* Extend the file's size */
            if (MPI_SUCCESS != (mpi_code = MPI_File_set_size(file->f, needed_eof)))
                HMPI_GOTO_ERROR(FAIL, "MPI_File_set_size failed", mpi_code)

            /* In general, we must wait until all processes have finished
             * the truncate before any process can continue, since it is
             * possible that a process would write at the end of the
             * file, and this write would be discarded by the truncate.
             *
             * While this is an issue for a user initiated flush, it may
             * not be an issue at file close.  If so, we may be able to
             * optimize out the following barrier in that case.
             */
            if (MPI_SUCCESS != (mpi_code = MPI_Barrier(file->comm)))
                HMPI_GOTO_ERROR(FAIL, "MPI_Barrier failed", mpi_code)
        } /* end if */

        /* Update the 'last' eoa value */
        file->last_eoa = file->eoa;
    } /* end if */

done:
#ifdef H5FDmpio_DEBUG
    if (H5FD_mpio_debug_t_flag)
        HDfprintf(stderr, "%s: (%d) Leaving\n", __func__, file->mpi_rank);
#endif

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD__mpio_truncate() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_delete
 *
 * Purpose:     Delete a file
 *
 * Return:      SUCCEED/FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_delete(const char *filename, hid_t fapl_id)
{
    H5P_genplist_t *plist; /* Property list pointer */
    MPI_Comm        comm     = MPI_COMM_NULL;
    MPI_Info        info     = MPI_INFO_NULL;
    int             mpi_rank = INT_MAX;
    int             mpi_code;            /* MPI return code */
    herr_t          ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_STATIC

    HDassert(filename);

    if (NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list")
    HDassert(H5FD_MPIO == H5P_peek_driver(plist));

    if (H5FD_mpi_self_initialized) {
        comm = MPI_COMM_WORLD;
    }
    else {
        /* Get the MPI communicator and info from the fapl */
        if (H5P_get(plist, H5F_ACS_MPI_PARAMS_INFO_NAME, &info) < 0)
            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "can't get MPI info object")
        if (H5P_get(plist, H5F_ACS_MPI_PARAMS_COMM_NAME, &comm) < 0)
            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "can't get MPI communicator")
    }

    /* Get the MPI rank of this process */
    if (MPI_SUCCESS != (mpi_code = MPI_Comm_rank(comm, &mpi_rank)))
        HMPI_GOTO_ERROR(FAIL, "MPI_Comm_rank failed", mpi_code)

    /* Set up a barrier */
    if (MPI_SUCCESS != (mpi_code = MPI_Barrier(comm)))
        HMPI_GOTO_ERROR(FAIL, "MPI_Barrier failed", mpi_code)

    /* Delete the file */
    if (mpi_rank == 0)
        if (MPI_SUCCESS != (mpi_code = MPI_File_delete(filename, info)))
            HMPI_GOTO_ERROR(FAIL, "MPI_File_delete failed", mpi_code)

    /* Set up a barrier (don't want processes to run ahead of the delete) */
    if (MPI_SUCCESS != (mpi_code = MPI_Barrier(comm)))
        HMPI_GOTO_ERROR(FAIL, "MPI_Barrier failed", mpi_code)

done:
    /* Free duplicated MPI Communicator and Info objects */
    if (H5_mpi_comm_free(&comm) < 0)
        HDONE_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "unable to free MPI communicator")
    if (H5_mpi_info_free(&info) < 0)
        HDONE_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "unable to free MPI info object")

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FD__mpio_delete() */

/*-------------------------------------------------------------------------
 * Function:    H5FD__mpio_ctl
 *
 * Purpose:     MPIO version of the ctl callback.
 *
 *              The desired operation is specified by the op_code
 *              parameter.
 *
 *              The flags parameter controls management of op_codes that
 *              are unknown to the callback
 *
 *              The input and output parameters allow op_code specific
 *              input and output
 *
 *              At present, the supported op codes are:
 *
 *                  H5FD_CTL__GET_MPI_COMMUNICATOR_OPCODE
 *                  H5FD_CTL__GET_MPI_RANK_OPCODE
 *                  H5FD_CTL__GET_MPI_SIZE_OPCODE
 *
 *              Note that these opcodes must be supported by all VFDs that
 *              support MPI.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 * Programmer:  JRM -- 8/3/21
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD__mpio_ctl(H5FD_t *_file, uint64_t op_code, uint64_t flags, const void H5_ATTR_UNUSED *input,
               void **output)
{
    H5FD_mpio_t *file      = (H5FD_mpio_t *)_file;
    herr_t       ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_NOAPI(FAIL)

    /* Sanity checks */
    HDassert(file);
    HDassert(H5FD_MPIO == file->pub.driver_id);

    switch (op_code) {

        case H5FD_CTL__GET_MPI_COMMUNICATOR_OPCODE:
            HDassert(output);
            HDassert(*output);
            **((MPI_Comm **)output) = file->comm;
            break;

        case H5FD_CTL__GET_MPI_RANK_OPCODE:
            HDassert(output);
            HDassert(*output);
            **((int **)output) = file->mpi_rank;
            break;

        case H5FD_CTL__GET_MPI_SIZE_OPCODE:
            HDassert(output);
            HDassert(*output);
            **((int **)output) = file->mpi_size;
            break;

        default: /* unknown op code */
            if (flags & H5FD_CTL__FAIL_IF_UNKNOWN_FLAG) {

                HGOTO_ERROR(H5E_VFL, H5E_FCNTL, FAIL, "unknown op_code and fail if unknown")
            }
            break;
    }

done:

    FUNC_LEAVE_NOAPI(ret_value)

} /* end H5FD__mpio_ctl() */
#endif /* H5_HAVE_PARALLEL */