summaryrefslogtreecommitdiffstats
path: root/src/H5FScache.c
blob: f5e9361c1ebf89bccfb925950f791f6eebae7f5f (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
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * 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.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*-------------------------------------------------------------------------
 *
 * Created:     H5FScache.c
 *
 * Purpose:     Implement file free space metadata cache methods.
 *
 *-------------------------------------------------------------------------
 */

/****************/
/* Module Setup */
/****************/

#include "H5FSmodule.h" /* This source code file is part of the H5FS module */

/***********/
/* Headers */
/***********/
#include "H5private.h"   /* Generic Functions			*/
#include "H5ACprivate.h" /* Metadata cache                       */
#include "H5Eprivate.h"  /* Error handling		  	*/
#include "H5Fprivate.h"  /* File          			*/
#include "H5FSpkg.h"     /* File free space			*/
#include "H5MFprivate.h" /* File memory management		*/
#include "H5MMprivate.h" /* Memory management			*/
#include "H5VMprivate.h" /* Vectors and arrays 			*/
#include "H5WBprivate.h" /* Wrapped Buffers                      */

/****************/
/* Local Macros */
/****************/

/* File free space format version #'s */
#define H5FS_HDR_VERSION   0 /* Header */
#define H5FS_SINFO_VERSION 0 /* Serialized sections */

/******************/
/* Local Typedefs */
/******************/

/* User data for skip list iterator callback for iterating over section size nodes when syncing */
typedef struct {
    H5FS_sinfo_t *sinfo;         /* Free space section info */
    uint8_t     **image;         /* Pointer to address of buffer pointer to serialize with */
    unsigned      sect_cnt_size; /* # of bytes to encode section size counts in */
} H5FS_iter_ud_t;

/********************/
/* Package Typedefs */
/********************/

/********************/
/* Local Prototypes */
/********************/

/* Section info routines */
static herr_t H5FS__sinfo_serialize_sect_cb(void *_item, void H5_ATTR_UNUSED *key, void *_udata);
static herr_t H5FS__sinfo_serialize_node_cb(void *_item, void H5_ATTR_UNUSED *key, void *_udata);

/* Metadata cache callbacks */
static herr_t H5FS__cache_hdr_get_initial_load_size(void *udata, size_t *image_len);
static htri_t H5FS__cache_hdr_verify_chksum(const void *image_ptr, size_t len, void *udata_ptr);
static void  *H5FS__cache_hdr_deserialize(const void *image, size_t len, void *udata, bool *dirty);
static herr_t H5FS__cache_hdr_image_len(const void *thing, size_t *image_len);
static herr_t H5FS__cache_hdr_pre_serialize(H5F_t *f, void *thing, haddr_t addr, size_t len,
                                            haddr_t *new_addr, size_t *new_len, unsigned *flags);
static herr_t H5FS__cache_hdr_serialize(const H5F_t *f, void *image, size_t len, void *thing);
static herr_t H5FS__cache_hdr_notify(H5AC_notify_action_t action, void *thing);
static herr_t H5FS__cache_hdr_free_icr(void *thing);

static herr_t H5FS__cache_sinfo_get_initial_load_size(void *udata, size_t *image_len);
static htri_t H5FS__cache_sinfo_verify_chksum(const void *image_ptr, size_t len, void *udata_ptr);
static void  *H5FS__cache_sinfo_deserialize(const void *image, size_t len, void *udata, bool *dirty);
static herr_t H5FS__cache_sinfo_image_len(const void *thing, size_t *image_len);
static herr_t H5FS__cache_sinfo_pre_serialize(H5F_t *f, void *thing, haddr_t addr, size_t len,
                                              haddr_t *new_addr, size_t *new_len, unsigned *flags);
static herr_t H5FS__cache_sinfo_serialize(const H5F_t *f, void *image, size_t len, void *thing);
static herr_t H5FS__cache_sinfo_notify(H5AC_notify_action_t action, void *thing);
static herr_t H5FS__cache_sinfo_free_icr(void *thing);

/*********************/
/* Package Variables */
/*********************/

/* H5FS header inherits cache-like properties from H5AC */
const H5AC_class_t H5AC_FSPACE_HDR[1] = {{
    H5AC_FSPACE_HDR_ID,                    /* Metadata client ID */
    "Free Space Header",                   /* Metadata client name (for debugging) */
    H5FD_MEM_FSPACE_HDR,                   /* File space memory type for client */
    H5AC__CLASS_NO_FLAGS_SET,              /* Client class behavior flags */
    H5FS__cache_hdr_get_initial_load_size, /* 'get_initial_load_size' callback */
    NULL,                                  /* 'get_final_load_size' callback */
    H5FS__cache_hdr_verify_chksum,         /* 'verify_chksum' callback */
    H5FS__cache_hdr_deserialize,           /* 'deserialize' callback */
    H5FS__cache_hdr_image_len,             /* 'image_len' callback */
    H5FS__cache_hdr_pre_serialize,         /* 'pre_serialize' callback */
    H5FS__cache_hdr_serialize,             /* 'serialize' callback */
    H5FS__cache_hdr_notify,                /* 'notify' callback */
    H5FS__cache_hdr_free_icr,              /* 'free_icr' callback */
    NULL,                                  /* 'fsf_size' callback */
}};

/* H5FS section info inherits cache-like properties from H5AC */
const H5AC_class_t H5AC_FSPACE_SINFO[1] = {{
    H5AC_FSPACE_SINFO_ID,                    /* Metadata client ID */
    "Free Space Section Info",               /* Metadata client name (for debugging) */
    H5FD_MEM_FSPACE_SINFO,                   /* File space memory type for client */
    H5AC__CLASS_NO_FLAGS_SET,                /* Client class behavior flags */
    H5FS__cache_sinfo_get_initial_load_size, /* 'get_initial_load_size' callback */
    NULL,                                    /* 'get_final_load_size' callback */
    H5FS__cache_sinfo_verify_chksum,         /* 'verify_chksum' callback */
    H5FS__cache_sinfo_deserialize,           /* 'deserialize' callback */
    H5FS__cache_sinfo_image_len,             /* 'image_len' callback */
    H5FS__cache_sinfo_pre_serialize,         /* 'pre_serialize' callback */
    H5FS__cache_sinfo_serialize,             /* 'serialize' callback */
    H5FS__cache_sinfo_notify,                /* 'notify' callback */
    H5FS__cache_sinfo_free_icr,              /* 'free_icr' callback */
    NULL,                                    /* 'fsf_size' callback */
}};

/*****************************/
/* Library Private Variables */
/*****************************/

/*******************/
/* Local Variables */
/*******************/

/*-------------------------------------------------------------------------
 * Function:    H5FS__cache_hdr_get_initial_load_size
 *
 * Purpose:     Compute the size of the data structure on disk.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_hdr_get_initial_load_size(void *_udata, size_t *image_len)
{
    H5FS_hdr_cache_ud_t *udata = (H5FS_hdr_cache_ud_t *)_udata; /* User-data for metadata cache callback */

    FUNC_ENTER_PACKAGE_NOERR

    /* Check arguments */
    assert(udata);
    assert(udata->f);
    assert(image_len);

    /* Set the image length size */
    *image_len = (size_t)H5FS_HEADER_SIZE(udata->f);

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5FS__cache_hdr_get_initial_load_size() */

/*-------------------------------------------------------------------------
 * Function:    H5FS__cache_hdr_verify_chksum
 *
 * Purpose:     Verify the computed checksum of the data structure is the
 *              same as the stored chksum.
 *
 * Return:      Success:        true/false
 *              Failure:        Negative
 *
 *-------------------------------------------------------------------------
 */
htri_t
H5FS__cache_hdr_verify_chksum(const void *_image, size_t len, void H5_ATTR_UNUSED *_udata)
{
    const uint8_t *image = (const uint8_t *)_image; /* Pointer into raw data buffer */
    uint32_t       stored_chksum;                   /* Stored metadata checksum value */
    uint32_t       computed_chksum;                 /* Computed metadata checksum value */
    htri_t         ret_value = true;                /* Return value */

    FUNC_ENTER_PACKAGE_NOERR

    /* Check arguments */
    assert(image);

    /* Get stored and computed checksums */
    H5F_get_checksums(image, len, &stored_chksum, &computed_chksum);

    if (stored_chksum != computed_chksum)
        ret_value = false;

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_hdr_verify_chksum() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__cache_hdr_deserialize
 *
 * Purpose:	Given a buffer containing the on disk image of the free space
 *      	manager section info, allocate an instance of H5FS_t, load
 *      	it with the data contained in the image, and return a pointer
 *              to the new instance.
 *
 * Return:	Success:	Pointer to new object
 *		Failure:	NULL
 *
 *-------------------------------------------------------------------------
 */
static void *
H5FS__cache_hdr_deserialize(const void *_image, size_t H5_ATTR_NDEBUG_UNUSED len, void *_udata,
                            bool H5_ATTR_UNUSED *dirty)
{
    H5FS_t              *fspace = NULL;                          /* Free space header info */
    H5FS_hdr_cache_ud_t *udata  = (H5FS_hdr_cache_ud_t *)_udata; /* User data for callback */
    const uint8_t       *image  = (const uint8_t *)_image;       /* Pointer into raw data buffer */
    uint32_t             stored_chksum;                          /* Stored metadata checksum value */
    unsigned             nclasses;                               /* Number of section classes */
    H5FS_t              *ret_value = NULL;                       /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check arguments */
    assert(image);
    assert(udata);
    assert(udata->f);

    /* Allocate a new free space manager */
    if (NULL == (fspace = H5FS__new(udata->f, udata->nclasses, udata->classes, udata->cls_init_udata)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");

    /* Set free space manager's internal information */
    fspace->addr = udata->addr;

    /* Magic number */
    if (memcmp(image, H5FS_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC) != 0)
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTLOAD, NULL, "wrong free space header signature");
    image += H5_SIZEOF_MAGIC;

    /* Version */
    if (*image++ != H5FS_HDR_VERSION)
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTLOAD, NULL, "wrong free space header version");

    /* Client ID */
    fspace->client = (H5FS_client_t)*image++;
    if (fspace->client >= H5FS_NUM_CLIENT_ID)
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTLOAD, NULL, "unknown client ID in free space header");

    /* Total space tracked */
    H5F_DECODE_LENGTH(udata->f, image, fspace->tot_space);

    /* Total # of free space sections tracked */
    H5F_DECODE_LENGTH(udata->f, image, fspace->tot_sect_count);

    /* # of serializable free space sections tracked */
    H5F_DECODE_LENGTH(udata->f, image, fspace->serial_sect_count);

    /* # of ghost free space sections tracked */
    H5F_DECODE_LENGTH(udata->f, image, fspace->ghost_sect_count);

    /* # of section classes */
    /* (only check if we actually have some classes) */
    UINT16DECODE(image, nclasses);
    if (fspace->nclasses > 0 && nclasses > fspace->nclasses)
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTLOAD, NULL, "section class count mismatch");

    /* Shrink percent */
    UINT16DECODE(image, fspace->shrink_percent);

    /* Expand percent */
    UINT16DECODE(image, fspace->expand_percent);

    /* Size of address space free space sections are within
     * (log2 of actual value)
     */
    UINT16DECODE(image, fspace->max_sect_addr);

    /* Max. size of section to track */
    H5F_DECODE_LENGTH(udata->f, image, fspace->max_sect_size);

    /* Address of serialized free space sections */
    H5F_addr_decode(udata->f, &image, &fspace->sect_addr);

    /* Size of serialized free space sections */
    H5F_DECODE_LENGTH(udata->f, image, fspace->sect_size);

    /* Allocated size of serialized free space sections */
    H5F_DECODE_LENGTH(udata->f, image, fspace->alloc_sect_size);

    /* checksum verification already done in verify_chksum cb */

    /* Metadata checksum */
    UINT32DECODE(image, stored_chksum);

    /* Sanity check */
    assert((size_t)(image - (const uint8_t *)_image) <= len);

    /* Set return value */
    ret_value = fspace;

done:
    /* Release resources */
    if (!ret_value && fspace)
        if (H5FS__hdr_dest(fspace) < 0)
            HDONE_ERROR(H5E_FSPACE, H5E_CANTFREE, NULL, "unable to destroy free space header");

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_hdr_deserialize() */

/*-------------------------------------------------------------------------
 * Function:    H5FS__cache_hdr_image_len
 *
 * Purpose:     Compute the size of the data structure on disk and return
 *              it in *image_len.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_hdr_image_len(const void *_thing, size_t *image_len)
{
    const H5FS_t *fspace = (const H5FS_t *)_thing; /* Pointer to the object */

    FUNC_ENTER_PACKAGE_NOERR

    /* Check arguments */
    assert(fspace);
    assert(fspace->cache_info.type == H5AC_FSPACE_HDR);
    assert(image_len);

    /* Set the image length size */
    *image_len = fspace->hdr_size;

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5FS__cache_hdr_image_len() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__cache_hdr_pre_serialize
 *
 * Purpose:	The free space manager header contains the address, size, and
 *		allocation size of the free space manager section info.  However,
 *		since it is possible for the section info to either not be allocated
 *		at all, or be allocated in temporary (AKA imaginary) files space,
 *		it is possible for the above mentioned fields to contain giberish
 *		when the free space manager header is serialized.
 *
 *		This function exists to prevent this problem.  It does so by
 *		forcing allocation of real file space for the section information.
 *
 *		Note that in the Version 2 cache, this problem was dealt with by
 *		simply flushing the section info before flushing the header.  This
 *		was possible, since the clients handled file I/O directly.  As
 *		this responsibility has moved to the cache in Version 3, this
 *		solution is no longer directly applicable.
 *
 * Return:	Success:	SUCCEED
 *		Failure:	FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_hdr_pre_serialize(H5F_t *f, void *_thing, haddr_t addr, size_t H5_ATTR_UNUSED len,
                              haddr_t H5_ATTR_NDEBUG_UNUSED *new_addr, size_t H5_ATTR_NDEBUG_UNUSED *new_len,
                              unsigned *flags)
{
    H5FS_t     *fspace    = (H5FS_t *)_thing; /* Pointer to the object */
    H5AC_ring_t orig_ring = H5AC_RING_INV;    /* Original ring value */
    herr_t      ret_value = SUCCEED;          /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    assert(f);
    assert(fspace);
    assert(fspace->cache_info.type == H5AC_FSPACE_HDR);
    assert(H5_addr_defined(addr));
    assert(new_addr);
    assert(new_len);
    assert(flags);

    if (fspace->sinfo) {
        H5AC_ring_t ring;

        /* Retrieve the ring type for the header */
        if (H5AC_get_entry_ring(f, addr, &ring) < 0)
            HGOTO_ERROR(H5E_FSPACE, H5E_CANTGET, FAIL, "unable to get property value");

        /* Set the ring type for the section info in the API context */
        H5AC_set_ring(ring, &orig_ring);

        /* This implies that the header "owns" the section info.
         *
         * Unfortunately, the comments in the code are not clear as to
         * what this means, but from reviewing the code (most particularly
         * H5FS_close(), H5FS_sinfo_lock, and H5FS_sinfo_unlock()), I
         * gather that it means that the header is maintaining a pointer to
         * an instance of H5FS_sinfo_t in which free space data is
         * maintained, and either:
         *
         * 1) The instance of H5FS_sinfo_t is not in the metadata cache.
         *
         *    This will be true iff H5_addr_defined(fspace->sect_addr)
         *    is false, and fspace->sinfo is not NULL.  This is sometimes
         *    referred to as "floating" section info in the comments.
         *
         *    If the section info structure contains free space data
         *    that must be placed on disk eventually, then
         *
         *        fspace->serial_sect_count > 0
         *
         *    and
         *
         *        H5_addr_defined(fspace->addr)
         *
         *    will both be true.  If this condition does not hold, then
         *    either the free space info is not persistent
         *    (!H5_addr_defined(fspace->addr)???) or the section info
         *    contains no free space data that must be written to file
         *    ( fspace->serial_sect_count == 0 ).
         *
         * 2) The instance of H5FS_sinfo_t is in the metadata cache with
         *    address in temporary file space (AKA imaginary file space).
         *    The entry may or may not be protected, and if protected, it
         *    may be protected either RW or RO (as indicated by
         *    fspace->sinfo_protected and  fspace->sinfo_accmod).
         *
         * 3) The instance of H5FS_sinfo_t is in the metadata cache with
         *    address in real file space.  As in case 2) above, the entry
         *    may or may not be protected, and if protected, it
         *    may be protected either RW or RO (as indicated by
         *    fspace->sinfo_protected and  fspace->sinfo_accmod).
         *
         * Observe that fspace->serial_sect_count > 0 must be true in
         * cases 2) and 3), as the section info should not be stored on
         * disk if it doesn't exist.  Similarly, since the section info
         * will not be stored to disk unless the header is,
         * H5_addr_defined(fspace->addr) must hold as well.
         *
         * As the objective is to touch up the free space manager header
         * so that it contains sensical data on the size and location of
         * the section information, we have to handle each of the above
         * cases differently.
         *
         * Case 1) If either fspace->serial_sect_count == 0 or
         *         ! H5_addr_defined(fspace->addr) do nothing as either
         *         the free space manager data is not persistent, or the
         *         section info is empty.
         *
         *         Otherwise, allocate space for the section info in real
         *         file space, insert the section info at this location, and
         *         set fspace->sect_addr, fspace->sect_size, and
         *         fspace->alloc_sect_size to reflect the new location
         *         of the section info.  Note that it is not necessary to
         *         force a write of the section info.
         *
         * Case 2) Allocate space for the section info in real file space,
         *         and tell the metadata cache to relocate the entry.
         *         Update fspace->sect_addr, fspace->sect_size, and
         *         fspace->alloc_sect_size to reflect the new location.
         *
         * Case 3) Nothing to be done in this case, although it is useful
         *         to perform sanity checks.
         *
         * Note that while we may alter the contents of the free space
         * header in cases 1) and 2), there is no need to mark the header
         * as dirty, as the metadata cache would not be attempting to
         * serialize the header if it thought it was clean.
         */
        if (fspace->serial_sect_count > 0 && H5_addr_defined(fspace->addr)) {
            /* Sanity check */
            assert(fspace->sect_size > 0);

            if (!H5_addr_defined(fspace->sect_addr)) { /* case 1 */
                haddr_t tag = HADDR_UNDEF;
                haddr_t sect_addr;
                hsize_t saved_sect_size, new_sect_size;

                /* allocate file space for the section info, and insert it
                 * into the metadata cache.
                 */
                saved_sect_size = fspace->sect_size;
                if (HADDR_UNDEF ==
                    (sect_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FSPACE_SINFO, fspace->sect_size)))
                    HGOTO_ERROR(H5E_FSPACE, H5E_NOSPACE, FAIL,
                                "file allocation failed for free space sections");

                /* fspace->sect_size may change in size after H5MF_alloc().
                 * If increased in size, free the previous allocation and
                 * allocate again with the bigger fspace->sect_size.
                 */
                if (fspace->sect_size > saved_sect_size) {

                    new_sect_size = fspace->sect_size;

                    if (H5MF_xfree(f, H5FD_MEM_FSPACE_SINFO, sect_addr, saved_sect_size) < 0)
                        HGOTO_ERROR(H5E_FSPACE, H5E_CANTFREE, FAIL, "unable to free free space sections");

                    if (HADDR_UNDEF ==
                        (sect_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FSPACE_SINFO, new_sect_size)))
                        HGOTO_ERROR(H5E_FSPACE, H5E_NOSPACE, FAIL,
                                    "file allocation failed for free space sections");
                    fspace->sect_size       = new_sect_size;
                    fspace->alloc_sect_size = new_sect_size;
                }
                else {
                    fspace->alloc_sect_size = saved_sect_size;
                    fspace->sect_size       = saved_sect_size;
                }
                fspace->sect_addr = sect_addr;

                /* Get the tag for this free space manager and use it to insert the entry */
                if (H5AC_get_tag((const void *)fspace, &tag) < 0)
                    HGOTO_ERROR(H5E_FSPACE, H5E_CANTTAG, FAIL, "can't get tag for metadata cache object");
                H5_BEGIN_TAG(tag)
                if (H5AC_insert_entry((H5F_t *)f, H5AC_FSPACE_SINFO, fspace->sect_addr, fspace->sinfo,
                                      H5AC__NO_FLAGS_SET) < 0)
                    HGOTO_ERROR_TAG(H5E_FSPACE, H5E_CANTINIT, FAIL, "can't add free space sections to cache");
                H5_END_TAG

                assert(fspace->sinfo->cache_info.size == fspace->alloc_sect_size);

                /* the metadata cache is now managing the section info,
                 * so set fspace->sinfo to NULL.
                 */
                fspace->sinfo = NULL;
            }                                                 /* end if */
            else if (H5F_IS_TMP_ADDR(f, fspace->sect_addr)) { /* case 2 */
                haddr_t new_sect_addr;

                /* move the section info from temporary (AKA imaginary) file
                 * space to real file space.
                 */

                /* if my reading of the code is correct, this should always
                 * be the case.  If not, we will have to add code to resize
                 * file space allocation for section info as well as moving it.
                 */
                assert(fspace->sect_size > 0);
                assert(fspace->alloc_sect_size == (size_t)fspace->sect_size);

                /* Allocate space for the section info in file */
                if (HADDR_UNDEF ==
                    (new_sect_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FSPACE_SINFO, fspace->sect_size)))
                    HGOTO_ERROR(H5E_FSPACE, H5E_NOSPACE, FAIL,
                                "file allocation failed for free space sections");

                fspace->alloc_sect_size = (size_t)fspace->sect_size;
                assert(fspace->sinfo->cache_info.size == fspace->alloc_sect_size);

                /* Let the metadata cache know the section info moved */
                if (H5AC_move_entry((H5F_t *)f, H5AC_FSPACE_SINFO, fspace->sect_addr, new_sect_addr) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move section info");

                fspace->sect_addr = new_sect_addr;
            }      /* end else-if */
            else { /* case 3 -- nothing to do but sanity checking */
                /* if my reading of the code is correct, this should always
                 * be the case.  If not, we will have to add code to resize
                 * file space allocation for section info.
                 */
                assert(fspace->sect_size > 0);
                assert(fspace->alloc_sect_size == (size_t)fspace->sect_size);
            } /* end else */
        }     /* end else */
        else {
            /* for one reason or another (see comment above) there should
             * not be any file space allocated for the section info.
             */
            assert(!H5_addr_defined(fspace->sect_addr));
        } /* end else */
    }     /* end if */
    else if (H5_addr_defined(fspace->sect_addr)) {
        /* Here the metadata cache is managing the section info.
         *
         * Do some sanity checks, and then test to see if the section
         * info is in real file space.  If it isn't relocate it into
         * real file space lest the header be written to file with
         * a nonsense section info address.
         */
        if (!H5F_POINT_OF_NO_RETURN(f)) {
            assert(fspace->sect_size > 0);
            assert(fspace->alloc_sect_size == (size_t)fspace->sect_size);
        } /* end if */

        if (H5F_IS_TMP_ADDR(f, fspace->sect_addr)) {
            unsigned sect_status = 0;
            haddr_t  new_sect_addr;

            /* we have work to do -- must relocate section info into
             * real file space.
             *
             * Since the section info address is in temporary space (AKA
             * imaginary space), it follows that the entry must be in
             * cache.  Further, since fspace->sinfo is NULL, it must be
             * unprotected and un-pinned.  Start by verifying this.
             */
            if (H5AC_get_entry_status(f, fspace->sect_addr, &sect_status) < 0)
                HGOTO_ERROR(H5E_FSPACE, H5E_CANTGET, FAIL, "can't get section info status");

            assert(sect_status & H5AC_ES__IN_CACHE);
            assert((sect_status & H5AC_ES__IS_PROTECTED) == 0);
            assert((sect_status & H5AC_ES__IS_PINNED) == 0);

            /* Allocate space for the section info in file */
            if (HADDR_UNDEF ==
                (new_sect_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FSPACE_SINFO, fspace->sect_size)))
                HGOTO_ERROR(H5E_FSPACE, H5E_NOSPACE, FAIL, "file allocation failed for free space sections");

            fspace->alloc_sect_size = (size_t)fspace->sect_size;

            /* Sanity check */
            assert(!H5_addr_eq(fspace->sect_addr, new_sect_addr));

            /* Let the metadata cache know the section info moved */
            if (H5AC_move_entry((H5F_t *)f, H5AC_FSPACE_SINFO, fspace->sect_addr, new_sect_addr) < 0)
                HGOTO_ERROR(H5E_FSPACE, H5E_CANTMOVE, FAIL, "unable to move section info");

            /* Update the internal address for the section info */
            fspace->sect_addr = new_sect_addr;

            /* No need to mark the header dirty, as we are about to
             * serialize it.
             */
        }  /* end if */
    }      /* end else-if */
    else { /* there is no section info at present */
        /* do some sanity checks */
        assert(fspace->serial_sect_count == 0);
        assert(fspace->tot_sect_count == fspace->ghost_sect_count);
    } /* end else */

    /* what ever happened above, set *flags to 0 */
    *flags = 0;

done:
    /* Reset the ring in the API context */
    if (orig_ring != H5AC_RING_INV)
        H5AC_set_ring(orig_ring, NULL);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_hdr_pre_serialize() */

/*-------------------------------------------------------------------------
 * Function:    H5FS__cache_hdr_serialize
 *
 * Purpose: 	Given an instance of H5FS_t and a suitably sized buffer,
 *      	serialize the contents of the instance of H5FS_t and write
 *      	its contents to the buffer.  This buffer will be used to
 *      	write the image of the instance to file.
 *
 * Return:      Success:        SUCCEED
 *              Failure:        FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_hdr_serialize(const H5F_t *f, void *_image, size_t H5_ATTR_NDEBUG_UNUSED len, void *_thing)
{
    H5FS_t  *fspace = (H5FS_t *)_thing;  /* Pointer to the object */
    uint8_t *image  = (uint8_t *)_image; /* Pointer into raw data buffer */
    uint32_t metadata_chksum;            /* Computed metadata checksum value */
    herr_t   ret_value = SUCCEED;        /* Return value */

    FUNC_ENTER_PACKAGE_NOERR

    /* Check arguments */
    assert(f);
    assert(image);
    assert(fspace);
    assert(fspace->cache_info.type == H5AC_FSPACE_HDR);
    assert(fspace->hdr_size == len);

    /* The section information does not always exits, and if it does,
     * it is not always in the cache.  To make matters more interesting,
     * even if it is in the cache, it may not be in real file space.
     *
     * The pre-serialize function should have moved the section info
     * into real file space if necessary before this function was called.
     * The following asserts are a cursory check on this.
     */
    assert((!H5_addr_defined(fspace->sect_addr)) || (!H5F_IS_TMP_ADDR(f, fspace->sect_addr)));

    if (!H5F_POINT_OF_NO_RETURN(f))
        assert((!H5_addr_defined(fspace->sect_addr)) ||
               ((fspace->sect_size > 0) && (fspace->alloc_sect_size == (size_t)fspace->sect_size)));

    /* Magic number */
    H5MM_memcpy(image, H5FS_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC);
    image += H5_SIZEOF_MAGIC;

    /* Version # */
    *image++ = H5FS_HDR_VERSION;

    /* Client ID */
    H5_CHECKED_ASSIGN(*image++, uint8_t, fspace->client, int);

    /* Total space tracked */
    H5F_ENCODE_LENGTH(f, image, fspace->tot_space);

    /* Total # of free space sections tracked */
    H5F_ENCODE_LENGTH(f, image, fspace->tot_sect_count);

    /* # of serializable free space sections tracked */
    H5F_ENCODE_LENGTH(f, image, fspace->serial_sect_count);

    /* # of ghost free space sections tracked */
    H5F_ENCODE_LENGTH(f, image, fspace->ghost_sect_count);

    /* # of section classes */
    UINT16ENCODE(image, fspace->nclasses);

    /* Shrink percent */
    UINT16ENCODE(image, fspace->shrink_percent);

    /* Expand percent */
    UINT16ENCODE(image, fspace->expand_percent);

    /* Size of address space free space sections are within (log2 of
     * actual value)
     */
    UINT16ENCODE(image, fspace->max_sect_addr);

    /* Max. size of section to track */
    H5F_ENCODE_LENGTH(f, image, fspace->max_sect_size);

    /* Address of serialized free space sections */
    H5F_addr_encode(f, &image, fspace->sect_addr);

    /* Size of serialized free space sections */
    H5F_ENCODE_LENGTH(f, image, fspace->sect_size);

    /* Allocated size of serialized free space sections */
    H5F_ENCODE_LENGTH(f, image, fspace->alloc_sect_size);

    /* Compute checksum */
    metadata_chksum = H5_checksum_metadata((uint8_t *)_image, (size_t)(image - (uint8_t *)_image), 0);

    /* Metadata checksum */
    UINT32ENCODE(image, metadata_chksum);

    /* sanity checks */
    assert((size_t)(image - (uint8_t *)_image) == fspace->hdr_size);

    FUNC_LEAVE_NOAPI(ret_value)
} /* H5FS__cache_hdr_serialize() */

/*-------------------------------------------------------------------------
 * Function:    H5FS__cache_hdr_notify
 *
 * Purpose:     Handle cache action notifications
 *
 * Return:      SUCCEED/FAIL
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5FS__cache_hdr_notify(H5AC_notify_action_t action, void *_thing)
{
    H5FS_t *fspace    = (H5FS_t *)_thing; /* Pointer to the object */
    herr_t  ret_value = SUCCEED;          /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Sanity check */
    assert(fspace);

    /* Determine which action to take */
    switch (action) {
        case H5AC_NOTIFY_ACTION_AFTER_INSERT:
        case H5AC_NOTIFY_ACTION_AFTER_LOAD:
        case H5AC_NOTIFY_ACTION_AFTER_FLUSH:
            /* do nothing */
            break;

        case H5AC_NOTIFY_ACTION_ENTRY_DIRTIED:
            if (H5AC_unsettle_entry_ring(fspace) < 0)
                HGOTO_ERROR(H5E_FSPACE, H5E_CANTFLUSH, FAIL, "unable to mark FSM ring as unsettled");
            break;

        case H5AC_NOTIFY_ACTION_ENTRY_CLEANED:
        case H5AC_NOTIFY_ACTION_CHILD_DIRTIED:
        case H5AC_NOTIFY_ACTION_CHILD_CLEANED:
        case H5AC_NOTIFY_ACTION_CHILD_UNSERIALIZED:
        case H5AC_NOTIFY_ACTION_CHILD_SERIALIZED:
        case H5AC_NOTIFY_ACTION_BEFORE_EVICT:
            /* do nothing */
            break;

        default:
#ifdef NDEBUG
            HGOTO_ERROR(H5E_FSPACE, H5E_BADVALUE, FAIL, "unknown action from metadata cache");
#else  /* NDEBUG */
            assert(0 && "Unknown action?!?");
#endif /* NDEBUG */
    }  /* end switch */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_hdr_notify() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__cache_hdr_free_icr
 *
 * Purpose:	Destroys a free space header in memory.
 *
 * Return:	Success:        SUCCEED
 *              Failure:        FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_hdr_free_icr(void *_thing)
{
    H5FS_t *fspace    = (H5FS_t *)_thing; /* Pointer to the object */
    herr_t  ret_value = SUCCEED;          /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(fspace);
    assert(fspace->cache_info.type == H5AC_FSPACE_HDR);

    /* We should not still be holding on to the free space section info */
    assert(!fspace->sinfo);

    /* Destroy free space header */
    if (H5FS__hdr_dest(fspace) < 0)
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTFREE, FAIL, "unable to destroy free space header");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_hdr_free_icr() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__cache_sinfo_get_initial_load_size()
 *
 * Purpose:	Compute the size of the on disk image of the free space
 *		manager section info, and place this value in *image_len.
 *
 * Return:	Success:	SUCCEED
 *		Failure:	FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_sinfo_get_initial_load_size(void *_udata, size_t *image_len)
{
    const H5FS_t          *fspace;                                  /* free space manager */
    H5FS_sinfo_cache_ud_t *udata = (H5FS_sinfo_cache_ud_t *)_udata; /* User data for callback */

    FUNC_ENTER_PACKAGE_NOERR

    /* Sanity checks */
    assert(udata);
    fspace = udata->fspace;
    assert(fspace);
    assert(fspace->sect_size > 0);
    assert(image_len);

    /* Set the image length size */
    *image_len = (size_t)(fspace->sect_size);

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5FS__cache_sinfo_get_initial_load_size() */

/*-------------------------------------------------------------------------
 * Function:    H5FS__cache_sinfo_verify_chksum
 *
 * Purpose:     Verify the computed checksum of the data structure is the
 *              same as the stored chksum.
 *
 * Return:      Success:        true/false
 *              Failure:        Negative
 *
 *-------------------------------------------------------------------------
 */
htri_t
H5FS__cache_sinfo_verify_chksum(const void *_image, size_t len, void H5_ATTR_UNUSED *_udata)
{
    const uint8_t *image = (const uint8_t *)_image; /* Pointer into raw data buffer */
    uint32_t       stored_chksum;                   /* Stored metadata checksum value */
    uint32_t       computed_chksum;                 /* Computed metadata checksum value */
    htri_t         ret_value = true;                /* Return value */

    FUNC_ENTER_PACKAGE_NOERR

    /* Check arguments */
    assert(image);

    /* Get stored and computed checksums */
    H5F_get_checksums(image, len, &stored_chksum, &computed_chksum);

    if (stored_chksum != computed_chksum)
        ret_value = false;

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_sinfo_verify_chksum() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__cache_sinfo_deserialize
 *
 * Purpose:	Given a buffer containing the on disk image of the free space
 *		manager section info, allocate an instance of H5FS_sinfo_t, load
 *		it with the data contained in the image, and return a pointer to
 *		the new instance.
 *
 * Return:	Success:	Pointer to in core representation
 *		Failure:	NULL
 *
 *-------------------------------------------------------------------------
 */
static void *
H5FS__cache_sinfo_deserialize(const void *_image, size_t H5_ATTR_NDEBUG_UNUSED len, void *_udata,
                              bool H5_ATTR_NDEBUG_UNUSED *dirty)
{
    H5FS_sinfo_cache_ud_t *udata = (H5FS_sinfo_cache_ud_t *)_udata; /* User data for callback */
    H5FS_t                *fspace;                                  /* free space manager */
    H5FS_sinfo_t          *sinfo = NULL;                            /* Free space section info */
    haddr_t                fs_addr;                                 /* Free space header address */
    size_t                 old_sect_size;                           /* Old section size */
    const uint8_t         *image = (const uint8_t *)_image;         /* Pointer into raw data buffer */
    const uint8_t         *chksum_image;                            /* Points to chksum location */
    uint32_t               stored_chksum;                           /* Stored metadata checksum  */
    void                  *ret_value = NULL;                        /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(image);
    assert(udata);
    fspace = udata->fspace;
    assert(fspace);
    assert(fspace->sect_size == len);
    assert(dirty);

    /* Allocate a new free space section info */
    if (NULL == (sinfo = H5FS__sinfo_new(udata->f, fspace)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");

    /* initialize old_sect_size */
    H5_CHECKED_ASSIGN(old_sect_size, size_t, fspace->sect_size, hsize_t);

    /* Magic number */
    if (memcmp(image, H5FS_SINFO_MAGIC, (size_t)H5_SIZEOF_MAGIC) != 0)
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTLOAD, NULL, "wrong free space sections signature");
    image += H5_SIZEOF_MAGIC;

    /* Version */
    if (*image++ != H5FS_SINFO_VERSION)
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTLOAD, NULL, "wrong free space sections version");

    /* Address of free space header for these sections */
    H5F_addr_decode(udata->f, &image, &fs_addr);
    if (H5_addr_ne(fs_addr, fspace->addr))
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTLOAD, NULL, "incorrect header address for free space sections");

    /* Check for any serialized sections */
    if (fspace->serial_sect_count > 0) {
        hsize_t old_tot_sect_count; /* Total section count from header */
        hsize_t H5_ATTR_NDEBUG_UNUSED
            old_serial_sect_count;                          /* Total serializable section count from header */
        hsize_t H5_ATTR_NDEBUG_UNUSED old_ghost_sect_count; /* Total ghost section count from header */
        hsize_t H5_ATTR_NDEBUG_UNUSED old_tot_space;        /* Total space managed from header */
        unsigned                      sect_cnt_size;        /* The size of the section size counts */

        /* Compute the size of the section counts */
        sect_cnt_size = H5VM_limit_enc_size((uint64_t)fspace->serial_sect_count);

        /* Reset the section count, the "add" routine will update it */
        old_tot_sect_count        = fspace->tot_sect_count;
        old_serial_sect_count     = fspace->serial_sect_count;
        old_ghost_sect_count      = fspace->ghost_sect_count;
        old_tot_space             = fspace->tot_space;
        fspace->tot_sect_count    = 0;
        fspace->serial_sect_count = 0;
        fspace->ghost_sect_count  = 0;
        fspace->tot_space         = 0;

        /* Walk through the image, deserializing sections */
        do {
            hsize_t sect_size  = 0; /* Current section size */
            size_t  node_count = 0; /* # of sections of this size */
            size_t  u;              /* Local index variable */

            /* The number of sections of this node's size */
            UINT64DECODE_VAR(image, node_count, sect_cnt_size);
            assert(node_count);

            /* The size of the sections for this node */
            UINT64DECODE_VAR(image, sect_size, sinfo->sect_len_size);
            assert(sect_size);

            /* Loop over nodes of this size */
            for (u = 0; u < node_count; u++) {
                H5FS_section_info_t *new_sect;      /* Section that was deserialized */
                haddr_t              sect_addr = 0; /* Address of free space section in the address space */
                unsigned             sect_type;     /* Type of free space section */
                unsigned             des_flags;     /* Flags from deserialize callback */

                /* The address of the section */
                UINT64DECODE_VAR(image, sect_addr, sinfo->sect_off_size);

                /* The type of this section */
                sect_type = *image++;

                /* Call 'deserialize' callback for this section */
                des_flags = 0;
                assert(fspace->sect_cls[sect_type].deserialize);
                if (NULL == (new_sect = (*fspace->sect_cls[sect_type].deserialize)(
                                 &fspace->sect_cls[sect_type], image, sect_addr, sect_size, &des_flags)))
                    HGOTO_ERROR(H5E_FSPACE, H5E_CANTDECODE, NULL, "can't deserialize section");

                /* Update offset in serialization image */
                image += fspace->sect_cls[sect_type].serial_size;

                /* Insert section in free space manager, unless requested not to */
                if (!(des_flags & H5FS_DESERIALIZE_NO_ADD))
                    if (H5FS_sect_add(udata->f, fspace, new_sect, H5FS_ADD_DESERIALIZING, udata) < 0)
                        HGOTO_ERROR(H5E_FSPACE, H5E_CANTINSERT, NULL,
                                    "can't add section to free space manager");
            } /* end for */

            if (fspace->tot_sect_count == old_tot_sect_count)
                break;

        } while (image < (((const uint8_t *)_image + old_sect_size) - H5FS_SIZEOF_CHKSUM));

        /* Sanity check */
        assert((size_t)(image - (const uint8_t *)_image) <= (old_sect_size - H5FS_SIZEOF_CHKSUM));
        assert(old_sect_size == fspace->sect_size);
        assert(old_tot_sect_count == fspace->tot_sect_count);
        assert(old_serial_sect_count == fspace->serial_sect_count);
        assert(old_ghost_sect_count == fspace->ghost_sect_count);
        assert(old_tot_space == fspace->tot_space);
    } /* end if */

    /* checksum verification already done in verify_chksum cb */

    /* There may be empty space between entries and chksum */
    chksum_image = (const uint8_t *)(_image) + old_sect_size - H5FS_SIZEOF_CHKSUM;
    /* Metadata checksum */
    UINT32DECODE(chksum_image, stored_chksum);

    /* Sanity check */
    assert((image == chksum_image) ||
           ((size_t)((image - (const uint8_t *)_image) + (chksum_image - image)) == old_sect_size));

    /* Set return value */
    ret_value = sinfo;

done:
    if (!ret_value && sinfo)
        if (H5FS__sinfo_dest(sinfo) < 0)
            HDONE_ERROR(H5E_FSPACE, H5E_CANTFREE, NULL, "unable to destroy free space info");

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_sinfo_deserialize() */

/*-------------------------------------------------------------------------
 * Function:    H5FS__cache_sinfo_image_len
 *
 * Purpose:     Compute the size of the data structure on disk and return
 *              it in *image_len.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_sinfo_image_len(const void *_thing, size_t *image_len)
{
    const H5FS_sinfo_t *sinfo = (const H5FS_sinfo_t *)_thing; /* Pointer to the object */

    FUNC_ENTER_PACKAGE_NOERR

    /* Sanity checks */
    assert(sinfo);
    assert(sinfo->cache_info.type == H5AC_FSPACE_SINFO);
    assert(sinfo->fspace);
    assert(sinfo->fspace->cache_info.type == H5AC_FSPACE_HDR);
    assert(image_len);

    /* Set the image length size */
    H5_CHECKED_ASSIGN(*image_len, size_t, sinfo->fspace->alloc_sect_size, hsize_t);

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5FS__cache_sinfo_image_len() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__cache_sinfo_pre_serialize
 *
 * Purpose:	The objective of this function is to test to see if file space
 *		for the section info is located in temporary (AKA imaginary) file
 *		space.  If it is, relocate file space for the section info to
 *		regular file space.
 *
 * Return:	Success:	SUCCEED
 *		Failure:	FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_sinfo_pre_serialize(H5F_t *f, void *_thing, haddr_t addr, size_t H5_ATTR_NDEBUG_UNUSED len,
                                haddr_t *new_addr, size_t H5_ATTR_NDEBUG_UNUSED *new_len, unsigned *flags)
{
    H5FS_sinfo_t *sinfo = (H5FS_sinfo_t *)_thing; /* Pointer to the object */
    H5FS_t       *fspace;                         /* Free space header */
    haddr_t       sinfo_addr;                     /* Address for section info */
    herr_t        ret_value = SUCCEED;            /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(f);
    assert(sinfo);
    assert(sinfo->cache_info.type == H5AC_FSPACE_SINFO);
    fspace = sinfo->fspace;
    assert(fspace->cache_info.type == H5AC_FSPACE_HDR);
    assert(fspace->cache_info.is_pinned);
    assert(H5_addr_defined(addr));
    assert(H5_addr_eq(fspace->sect_addr, addr));
    assert(fspace->sect_size == len);
    assert(new_addr);
    assert(new_len);
    assert(flags);

    sinfo_addr = addr; /* this will change if we relocate the section data */

    /* Check for section info at temporary address */
    if (H5F_IS_TMP_ADDR(f, fspace->sect_addr)) {
        /* Sanity check */
        assert(fspace->sect_size > 0);
        assert(H5_addr_eq(fspace->sect_addr, addr));

        /* Allocate space for the section info in file */
        if (HADDR_UNDEF == (sinfo_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FSPACE_SINFO, fspace->sect_size)))
            HGOTO_ERROR(H5E_FSPACE, H5E_NOSPACE, FAIL, "file allocation failed for free space sections");

        fspace->alloc_sect_size = (size_t)fspace->sect_size;

        /* Sanity check */
        assert(!H5_addr_eq(sinfo->fspace->sect_addr, sinfo_addr));

        /* Let the metadata cache know the section info moved */
        if (H5AC_move_entry((H5F_t *)f, H5AC_FSPACE_SINFO, sinfo->fspace->sect_addr, sinfo_addr) < 0)
            HGOTO_ERROR(H5E_FSPACE, H5E_CANTMOVE, FAIL, "unable to move section info");

        /* Update the internal address for the section info */
        sinfo->fspace->sect_addr = sinfo_addr;

        /* Mark free space header as dirty */
        if (H5AC_mark_entry_dirty(fspace) < 0)
            HGOTO_ERROR(H5E_FSPACE, H5E_CANTMARKDIRTY, FAIL, "unable to mark free space header as dirty");
    } /* end if */

    if (!H5_addr_eq(addr, sinfo_addr)) {
        *new_addr = sinfo_addr;
        *flags    = H5C__SERIALIZE_MOVED_FLAG;
    } /* end if */
    else
        *flags = 0;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_sinfo_pre_serialize() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__cache_sinfo_serialize
 *
 * Purpose:	Given an instance of H5FS_sinfo_t and a suitably sized buffer,
 *		serialize the contents of the instance of H5FS_sinfo_t and write
 *		its contents to the buffer.  This buffer will be used to write
 *		the image of the instance to file.
 *
 * Return:	Success:	SUCCEED
 *		Failure:	FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_sinfo_serialize(const H5F_t *f, void *_image, size_t len, void *_thing)
{
    H5FS_sinfo_t  *sinfo = (H5FS_sinfo_t *)_thing; /* Pointer to the object */
    H5FS_iter_ud_t udata;                          /* User data for callbacks */
    ptrdiff_t      gap_size;
    uint8_t       *image        = (uint8_t *)_image; /* Pointer into raw data buffer */
    uint8_t       *chksum_image = NULL;              /* Points to chksum location */
    uint32_t       metadata_chksum;                  /* Computed metadata checksum value */
    unsigned       bin;                              /* Current bin we are on */
    herr_t         ret_value = SUCCEED;              /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(f);
    assert(image);
    assert(sinfo);
    assert(sinfo->cache_info.type == H5AC_FSPACE_SINFO);
    assert(sinfo->fspace->cache_info.type == H5AC_FSPACE_HDR);
    assert(sinfo->fspace->cache_info.is_pinned);
    assert(sinfo->fspace->sect_size == len);
    assert(sinfo->fspace->sect_cls);

    /* Magic number */
    H5MM_memcpy(image, H5FS_SINFO_MAGIC, (size_t)H5_SIZEOF_MAGIC);
    image += H5_SIZEOF_MAGIC;

    /* Version # */
    *image++ = H5FS_SINFO_VERSION;

    /* Address of free space header for these sections */
    H5F_addr_encode(f, &image, sinfo->fspace->addr);

    /* Set up user data for iterator */
    udata.sinfo         = sinfo;
    udata.image         = &image;
    udata.sect_cnt_size = H5VM_limit_enc_size((uint64_t)sinfo->fspace->serial_sect_count);

    /* Iterate over all the bins */
    for (bin = 0; bin < sinfo->nbins; bin++)
        /* Check if there are any sections in this bin */
        if (sinfo->bins[bin].bin_list)
            /* Iterate over list of section size nodes for bin */
            if (H5SL_iterate(sinfo->bins[bin].bin_list, H5FS__sinfo_serialize_node_cb, &udata) < 0)
                HGOTO_ERROR(H5E_FSPACE, H5E_BADITER, FAIL, "can't iterate over section size nodes");

    /* Compute checksum */

    /* There may be empty space between entries and chksum */
    chksum_image = (uint8_t *)(_image) + len - H5FS_SIZEOF_CHKSUM;

    /*
     * If there is any empty space between the entries and
     * checksum, make sure that the space is initialized
     * before serializing it
     */
    gap_size = chksum_image - image;
    if (gap_size > 0)
        memset(image, 0, (size_t)gap_size);

    metadata_chksum = H5_checksum_metadata(_image, (size_t)(chksum_image - (uint8_t *)_image), 0);
    /* Metadata checksum */
    UINT32ENCODE(chksum_image, metadata_chksum);

    /* Sanity check */
    assert((chksum_image == image) ||
           ((size_t)((image - (uint8_t *)_image) + (chksum_image - image)) == sinfo->fspace->sect_size));
    assert(sinfo->fspace->sect_size <= sinfo->fspace->alloc_sect_size);

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_sinfo_serialize() */

/*-------------------------------------------------------------------------
 * Function:    H5FS__cache_sinfo_notify
 *
 * Purpose:     Handle cache action notifications
 *
 * Return:      SUCCEED/FAIL
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5FS__cache_sinfo_notify(H5AC_notify_action_t action, void *_thing)
{
    H5FS_sinfo_t *sinfo     = (H5FS_sinfo_t *)_thing;
    herr_t        ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    assert(sinfo);

    /* Check if the file was opened with SWMR-write access */
    if (sinfo->fspace->swmr_write) {
        /* Determine which action to take */
        switch (action) {
            case H5AC_NOTIFY_ACTION_AFTER_INSERT:
            case H5AC_NOTIFY_ACTION_AFTER_LOAD:
                /* Create flush dependency on parent */
                if (H5FS__create_flush_depend((H5AC_info_t *)sinfo->fspace, (H5AC_info_t *)sinfo) < 0)
                    HGOTO_ERROR(
                        H5E_FSPACE, H5E_CANTDEPEND, FAIL,
                        "unable to create flush dependency between data block and header, address = %llu",
                        (unsigned long long)sinfo->fspace->sect_addr);
                break;

            case H5AC_NOTIFY_ACTION_AFTER_FLUSH:
            case H5AC_NOTIFY_ACTION_ENTRY_DIRTIED:
            case H5AC_NOTIFY_ACTION_ENTRY_CLEANED:
            case H5AC_NOTIFY_ACTION_CHILD_DIRTIED:
            case H5AC_NOTIFY_ACTION_CHILD_CLEANED:
            case H5AC_NOTIFY_ACTION_CHILD_UNSERIALIZED:
            case H5AC_NOTIFY_ACTION_CHILD_SERIALIZED:
                /* do nothing */
                break;

            case H5AC_NOTIFY_ACTION_BEFORE_EVICT:
                /* Destroy flush dependency on parent */
                if (H5FS__destroy_flush_depend((H5AC_info_t *)sinfo->fspace, (H5AC_info_t *)sinfo) < 0)
                    HGOTO_ERROR(H5E_FSPACE, H5E_CANTUNDEPEND, FAIL, "unable to destroy flush dependency");
                break;

            default:
#ifdef NDEBUG
                HGOTO_ERROR(H5E_FSPACE, H5E_BADVALUE, FAIL, "unknown action from metadata cache");
#else     /* NDEBUG */
                assert(0 && "Unknown action?!?");
#endif    /* NDEBUG */
        } /* end switch */
    }     /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_sinfo_notify() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__cache_sinfo_free_icr
 *
 * Purpose:	Free the memory used for the in core representation of the
 *		free space manager section info.
 *
 * Return:	Success:	SUCCEED
 *		Failure:	FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__cache_sinfo_free_icr(void *_thing)
{
    H5FS_sinfo_t *sinfo     = (H5FS_sinfo_t *)_thing; /* Pointer to the object */
    herr_t        ret_value = SUCCEED;                /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(sinfo);
    assert(sinfo->cache_info.type == H5AC_FSPACE_SINFO);
    assert(sinfo->fspace->cache_info.type == H5AC_FSPACE_HDR);
    assert(sinfo->fspace->cache_info.is_pinned);

    /* Destroy free space info */
    if (H5FS__sinfo_dest(sinfo) < 0)
        HGOTO_ERROR(H5E_FSPACE, H5E_CANTFREE, FAIL, "unable to destroy free space info");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5FS__cache_sinfo_free_icr() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__sinfo_serialize_sect_cb
 *
 * Purpose:	Skip list iterator callback to serialize free space sections
 *              of a particular size
 *
 * Return:      SUCCEED/FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__sinfo_serialize_sect_cb(void *_item, void H5_ATTR_UNUSED *key, void *_udata)
{
    H5FS_section_class_t *sect_cls;                                 /* Class of section */
    H5FS_section_info_t  *sect      = (H5FS_section_info_t *)_item; /* Free space section to work on */
    H5FS_iter_ud_t       *udata     = (H5FS_iter_ud_t *)_udata;     /* Callback info */
    herr_t                ret_value = SUCCEED;                      /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check arguments. */
    assert(sect);
    assert(udata->sinfo);
    assert(udata->image);

    /* Get section's class */
    sect_cls = &udata->sinfo->fspace->sect_cls[sect->type];

    /* Check if this section should be serialized (i.e. is not a ghost section) */
    if (!(sect_cls->flags & H5FS_CLS_GHOST_OBJ)) {
        /* The address of the section */
        UINT64ENCODE_VAR(*udata->image, sect->addr, udata->sinfo->sect_off_size);

        /* The type of this section */
        *(*udata->image)++ = (uint8_t)sect->type;

        /* Call 'serialize' callback for this section */
        if (sect_cls->serialize) {
            if ((*sect_cls->serialize)(sect_cls, sect, *udata->image) < 0)
                HGOTO_ERROR(H5E_FSPACE, H5E_CANTSERIALIZE, FAIL, "can't synchronize section");

            /* Update offset in serialization buffer */
            (*udata->image) += sect_cls->serial_size;
        } /* end if */
        else
            assert(sect_cls->serial_size == 0);
    } /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* H5FS__sinfo_serialize_sect_cb() */

/*-------------------------------------------------------------------------
 * Function:	H5FS__sinfo_serialize_node_cb
 *
 * Purpose:	Skip list iterator callback to serialize free space sections
 *              in a bin
 *
 * Return:      SUCCEED/FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5FS__sinfo_serialize_node_cb(void *_item, void H5_ATTR_UNUSED *key, void *_udata)
{
    H5FS_node_t    *fspace_node = (H5FS_node_t *)_item;     /* Free space size node to work on */
    H5FS_iter_ud_t *udata       = (H5FS_iter_ud_t *)_udata; /* Callback info */
    herr_t          ret_value   = SUCCEED;                  /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check arguments. */
    assert(fspace_node);
    assert(udata->sinfo);
    assert(udata->image);

    /* Check if this node has any serializable sections */
    if (fspace_node->serial_count > 0) {
        /* The number of serializable sections of this node's size */
        UINT64ENCODE_VAR(*udata->image, fspace_node->serial_count, udata->sect_cnt_size);

        /* The size of the sections for this node */
        UINT64ENCODE_VAR(*udata->image, fspace_node->sect_size, udata->sinfo->sect_len_size);

        /* Iterate through all the sections of this size */
        assert(fspace_node->sect_list);
        if (H5SL_iterate(fspace_node->sect_list, H5FS__sinfo_serialize_sect_cb, udata) < 0)
            HGOTO_ERROR(H5E_FSPACE, H5E_BADITER, FAIL, "can't iterate over section nodes");
    } /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* H5FS__sinfo_serialize_node_cb() */