summaryrefslogtreecommitdiffstats
path: root/xlators/experimental/jbr-server/src/jbr.c
blob: 68badb850791a6f88f67e859aa1a3df8c3ecda87 (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
/*
   Copyright (c) 2013 Red Hat, Inc. <http://www.redhat.com>
   This file is part of GlusterFS.

   This file is licensed to you under your choice of the GNU Lesser
   General Public License, version 3 or any later version (LGPLv3 or
   later), or the GNU General Public License, version 2 (GPLv2), in all
   cases as published by the Free Software Foundation.
*/

#ifndef _CONFIG_H
#define _CONFIG_H
#include "config.h"
#endif

#include <fnmatch.h>
#include "call-stub.h"
#include "defaults.h"
#include "xlator.h"
#include "glfs.h"
#include "glfs-internal.h"
#include "run.h"
#include "common-utils.h"
#include "syncop.h"
#include "syscall.h"
#include "compat-errno.h"

#include "jbr-internal.h"
#include "jbr-messages.h"

#define JBR_FLUSH_INTERVAL      5

enum {
        /* echo "cluster/jbr-server" | md5sum | cut -c 1-8 */
        JBR_SERVER_IPC_BASE = 0x0e2d66a5,
        JBR_SERVER_TERM_RANGE,
        JBR_SERVER_OPEN_TERM,
        JBR_SERVER_NEXT_ENTRY
};

/*
 * Need to declare jbr_lk_call_dispatch as jbr_lk_continue and *
 * jbr_lk_perform_local_op call it, before code is generated.  *
 */
int32_t
jbr_lk_call_dispatch (call_frame_t *frame, xlator_t *this, int *op_errno,
                      fd_t *fd, int32_t cmd, struct gf_flock *lock,
                      dict_t *xdata);

int32_t
jbr_lk_dispatch (call_frame_t *frame, xlator_t *this,
                 fd_t *fd, int32_t cmd, struct gf_flock *lock,
                 dict_t *xdata);

/* Used to check the quorum of acks received after the fop
 * confirming the status of the fop on all the brick processes
 * for this particular subvolume
 */
gf_boolean_t
fop_quorum_check (xlator_t *this, double n_children,
                  double current_state)
{
        jbr_private_t   *priv           = NULL;
        gf_boolean_t     result         = _gf_false;
        double           required       = 0;
        double           current        = 0;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);
        priv = this->private;
        GF_VALIDATE_OR_GOTO (this->name, priv, out);

        required = n_children * priv->quorum_pct;

        /*
         * Before performing the fop on the leader, we need to check,
         * if there is any merit in performing the fop on the leader.
         * In a case, where even a successful write on the leader, will
         * not meet quorum, there is no point in trying the fop on the
         * leader.
         * When this function is called after the leader has tried
         * performing the fop, this check will calculate quorum taking into
         * account the status of the fop on the leader. If the leader's
         * op_ret was -1, the complete function would account that by
         * decrementing successful_acks by 1
         */

        current = current_state * 100.0;

        if (current < required) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_QUORUM_NOT_MET,
                        "Quorum not met. quorum_pct = %f "
                        "Current State = %f, Required State = %f",
                        priv->quorum_pct, current,
                        required);
        } else
                result = _gf_true;

out:
        return result;
}

jbr_inode_ctx_t *
jbr_get_inode_ctx (xlator_t *this, inode_t *inode)
{
        uint64_t                ctx_int         = 0LL;
        jbr_inode_ctx_t         *ctx_ptr;

        if (__inode_ctx_get(inode, this, &ctx_int) == 0) {
                ctx_ptr = (jbr_inode_ctx_t *)(long)ctx_int;
        } else {
                ctx_ptr = GF_CALLOC (1, sizeof(*ctx_ptr),
                                     gf_mt_jbr_inode_ctx_t);
                if (ctx_ptr) {
                        ctx_int = (uint64_t)(long)ctx_ptr;
                        if (__inode_ctx_set(inode, this, &ctx_int) == 0) {
                                LOCK_INIT(&ctx_ptr->lock);
                                INIT_LIST_HEAD(&ctx_ptr->aqueue);
                                INIT_LIST_HEAD(&ctx_ptr->pqueue);
                        } else {
                                GF_FREE(ctx_ptr);
                                ctx_ptr = NULL;
                        }
                }

        }

        return ctx_ptr;
}

jbr_fd_ctx_t *
jbr_get_fd_ctx (xlator_t *this, fd_t *fd)
{
        uint64_t                ctx_int         = 0LL;
        jbr_fd_ctx_t            *ctx_ptr;

        if (__fd_ctx_get(fd, this, &ctx_int) == 0) {
                ctx_ptr = (jbr_fd_ctx_t *)(long)ctx_int;
        } else {
                ctx_ptr = GF_CALLOC (1, sizeof(*ctx_ptr), gf_mt_jbr_fd_ctx_t);
                if (ctx_ptr) {
                        if (__fd_ctx_set(fd, this, (uint64_t)ctx_ptr) == 0) {
                                INIT_LIST_HEAD(&ctx_ptr->dirty_list);
                                INIT_LIST_HEAD(&ctx_ptr->fd_list);
                        } else {
                                GF_FREE(ctx_ptr);
                                ctx_ptr = NULL;
                        }
                }

        }

        return ctx_ptr;
}

void
jbr_mark_fd_dirty (xlator_t *this, jbr_local_t *local)
{
        fd_t                    *fd             = local->fd;
        jbr_fd_ctx_t            *ctx_ptr;
        jbr_dirty_list_t        *dirty;
        jbr_private_t           *priv           = this->private;

        /*
         * TBD: don't do any of this for O_SYNC/O_DIRECT writes.
         * Unfortunately, that optimization requires that we distinguish
         * between writev and other "write" calls, saving the original flags
         * and checking them in the callback.  Too much work for too little
         * gain right now.
         */

        LOCK(&fd->lock);
                ctx_ptr = jbr_get_fd_ctx(this, fd);
                dirty = GF_CALLOC(1, sizeof(*dirty), gf_mt_jbr_dirty_t);
                if (ctx_ptr && dirty) {
                        gf_msg_trace (this->name, 0,
                                      "marking fd %p as dirty (%p)", fd, dirty);
                        /* TBD: fill dirty->id from what changelog gave us */
                        list_add_tail(&dirty->links, &ctx_ptr->dirty_list);
                        if (list_empty(&ctx_ptr->fd_list)) {
                                /* Add a ref so _release doesn't get called. */
                                ctx_ptr->fd = fd_ref(fd);
                                LOCK(&priv->dirty_lock);
                                        list_add_tail (&ctx_ptr->fd_list,
                                                       &priv->dirty_fds);
                                UNLOCK(&priv->dirty_lock);
                        }
                } else {
                        gf_msg (this->name, GF_LOG_ERROR, ENOMEM,
                                J_MSG_MEM_ERR, "could not mark %p dirty", fd);
                        if (ctx_ptr) {
                                GF_FREE(ctx_ptr);
                        }
                        if (dirty) {
                                GF_FREE(dirty);
                        }
                }
        UNLOCK(&fd->lock);
}

#define JBR_TERM_XATTR          "trusted.jbr.term"
#define JBR_INDEX_XATTR         "trusted.jbr.index"
#define JBR_REP_COUNT_XATTR     "trusted.jbr.rep-count"
#define RECON_TERM_XATTR        "trusted.jbr.recon-term"
#define RECON_INDEX_XATTR       "trusted.jbr.recon-index"

int32_t
jbr_leader_checks_and_init (call_frame_t *frame, xlator_t *this, int *op_errno,
                            dict_t *xdata, fd_t *fd)
{
        jbr_local_t     *local         = NULL;
        jbr_private_t   *priv          = NULL;
        int32_t          ret           = -1;
        gf_boolean_t     result        = _gf_false;
        int              from_leader   = _gf_false;
        int              from_recon    = _gf_false;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);
        priv = this->private;
        GF_VALIDATE_OR_GOTO (this->name, priv, out);
        GF_VALIDATE_OR_GOTO (this->name, op_errno, out);
        GF_VALIDATE_OR_GOTO (this->name, frame, out);

        /*
         * Our first goal here is to avoid "split brain surprise" for users who
         * specify exactly 50% with two- or three-way replication.  That means
         * either a more-than check against half the total replicas or an
         * at-least check against half of our peers (one less).  Of the two,
         * only an at-least check supports the intuitive use of 100% to mean
         * all replicas must be present, because "more than 100%" will never
         * succeed regardless of which count we use.  This leaves us with a
         * slightly non-traditional definition of quorum ("at least X% of peers
         * not including ourselves") but one that's useful enough to be worth
         * it.
         *
         * Note that n_children and up_children *do* include the local
         * subvolume, so we need to subtract one in each case.
         */
        if (priv->leader) {
                result = fop_quorum_check (this, (double)(priv->n_children - 1),
                                   (double)(priv->up_children - 1));

                if (result == _gf_false) {
                        /* Emulate the AFR client-side-quorum behavior. */
                        gf_msg (this->name, GF_LOG_ERROR, EROFS,
                                J_MSG_QUORUM_NOT_MET, "Sufficient number of "
                                "subvolumes are not up to meet quorum.");
                        *op_errno = EROFS;
                        goto out;
                }
        } else {
                if (xdata) {
                        from_leader = !!dict_get(xdata, JBR_TERM_XATTR);
                        from_recon = !!dict_get(xdata, RECON_TERM_XATTR)
                                  && !!dict_get(xdata, RECON_INDEX_XATTR);
                } else {
                        from_leader = from_recon = _gf_false;
                }

                /* follower/recon path        *
                 * just send it to local node *
                 */
                if (!from_leader && !from_recon) {
                        *op_errno = EREMOTE;
                        goto out;
                }
        }

        local = mem_get0(this->local_pool);
        if (!local) {
                goto out;
        }

        if (fd)
                local->fd = fd_ref(fd);
        else
                local->fd = NULL;

        INIT_LIST_HEAD(&local->qlinks);
        frame->local = local;

        ret = 0;
out:
        return ret;
}

int32_t
jbr_initialize_xdata_set_attrs (xlator_t *this, dict_t **xdata)
{
        jbr_local_t     *local         = NULL;
        jbr_private_t   *priv          = NULL;
        int32_t          ret           = -1;
        uint32_t         ti            = 0;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);
        priv = this->private;
        GF_VALIDATE_OR_GOTO (this->name, priv, out);
        GF_VALIDATE_OR_GOTO (this->name, xdata, out);

        if (!*xdata) {
                *xdata = dict_new();
                if (!*xdata) {
                        gf_msg (this->name, GF_LOG_ERROR, ENOMEM,
                                J_MSG_MEM_ERR, "failed to allocate xdata");
                        goto out;
                }
        }

        if (dict_set_int32(*xdata, JBR_TERM_XATTR, priv->current_term) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_DICT_FLR, "failed to set jbr-term");
                goto out;
        }

        LOCK(&priv->index_lock);
        ti = ++(priv->index);
        UNLOCK(&priv->index_lock);
        if (dict_set_int32(*xdata, JBR_INDEX_XATTR, ti) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_DICT_FLR, "failed to set index");
                goto out;
        }

        ret = 0;
out:
        return ret;
}

int32_t
jbr_remove_from_queue (call_frame_t *frame, xlator_t *this)
{
        int32_t          ret       = -1;
        jbr_inode_ctx_t *ictx      = NULL;
        jbr_local_t     *local     = NULL;
        jbr_local_t     *next      = NULL;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);
        GF_VALIDATE_OR_GOTO (this->name, frame, out);
        local = frame->local;
        GF_VALIDATE_OR_GOTO (this->name, local, out);

        if (local->qlinks.next != &local->qlinks) {
                list_del(&local->qlinks);
                ictx = jbr_get_inode_ctx(this, local->fd->inode);
                if (ictx) {
                        LOCK(&ictx->lock);
                                if (ictx->pending) {
                                        /*
                                         * TBD: dequeue *all* non-conflicting
                                         * reqs
                                         *
                                         * With the stub implementation there
                                         * can only be one request active at a
                                         * time (zero here) so it's not an
                                         * issue.  In a real implementation
                                         * there might still be other active
                                         * requests to check against, and
                                         * multiple pending requests that could
                                         * continue.
                                         */
                                        gf_msg_debug (this->name, 0,
                                                     "unblocking next request");
                                        --(ictx->pending);
                                        next = list_entry (ictx->pqueue.next,
                                                           jbr_local_t, qlinks);
                                        list_del(&next->qlinks);
                                        list_add_tail(&next->qlinks,
                                                      &ictx->aqueue);
                                        call_resume(next->qstub);
                                } else {
                                        --(ictx->active);
                                }
                        UNLOCK(&ictx->lock);
                }
        }

        ret = 0;

out:
        return ret;
}

int32_t
jbr_lk_complete (call_frame_t *frame, void *cookie, xlator_t *this,
                 int32_t op_ret, int32_t op_errno,
                 struct gf_flock *flock, dict_t *xdata)
{
        int32_t          ret       = -1;
        jbr_private_t   *priv      = NULL;
        jbr_local_t     *local     = NULL;
        gf_boolean_t     result    = _gf_false;

        GF_VALIDATE_OR_GOTO ("jbr", this, err);
        priv = this->private;
        GF_VALIDATE_OR_GOTO (this->name, priv, err);
        GF_VALIDATE_OR_GOTO (this->name, frame, err);
        local = frame->local;
        GF_VALIDATE_OR_GOTO (this->name, local, err);
        GF_VALIDATE_OR_GOTO (this->name, flock, err);
        GF_VALIDATE_OR_GOTO (this->name, xdata, err);

        /*
         * Remove from queue for unlock operation only   *
         * For lock operation, it will be done in fan-in *
         */
        if (flock->l_type == F_UNLCK) {
                ret = jbr_remove_from_queue (frame, this);
                if (ret)
                        goto err;
        }

        /*
         * On a follower, unwind with the op_ret and op_errno. On a *
         * leader, if the fop is a locking fop, and its a failure,  *
         * send fail, else call stub which will dispatch the fop to *
         * the followers.                                           *
         *                                                          *
         * If the fop is a unlocking fop, check quorum. If quorum   *
         * is met, then send success. Else Rollback on leader,      *
         * followed by followers, and then send -ve ack to client.  *
         */
        if (priv->leader) {

                /* Increase the successful acks if it's a success. */
                LOCK(&frame->lock);
                if (op_ret != -1)
                        (local->successful_acks)++;
                UNLOCK(&frame->lock);

                if (flock->l_type == F_UNLCK) {
                        result = fop_quorum_check (this,
                                            (double)priv->n_children,
                                            (double)local->successful_acks);
                        if (result == _gf_false) {
                                op_ret = -1;
                                op_errno = EROFS;
                                gf_msg (this->name, GF_LOG_ERROR, EROFS,
                                        J_MSG_QUORUM_NOT_MET,
                                        "Quorum is not met. "
                                        "The operation has failed.");

                                /* TODO: PERFORM UNLOCK ROLLBACK ON LEADER *
                                 * FOLLOWED BY FOLLOWERS. */
                        } else {
                                op_ret = 0;
                                op_errno = 0;
                        }

                        fd_unref(local->fd);
                        STACK_UNWIND_STRICT (lk, frame, op_ret, op_errno,
                                             flock, xdata);
                } else {
                        if (op_ret == -1) {
                                gf_msg (this->name, GF_LOG_ERROR, 0,
                                        J_MSG_LOCK_FAILURE,
                                        "The lock operation failed on "
                                        "the leader.");

                                fd_unref(local->fd);
                                STACK_UNWIND_STRICT (lk, frame, op_ret,
                                                     op_errno, flock, xdata);
                        } else {
                                if (!local->stub) {
                                        goto err;
                                }

                                call_resume(local->stub);
                        }
                }
        } else {
                fd_unref(local->fd);
                STACK_UNWIND_STRICT (lk, frame, op_ret, op_errno,
                                     flock, xdata);
        }

        return 0;

err:
        if (local) {
                if (local->stub) {
                        call_stub_destroy(local->stub);
                }
                if (local->qstub) {
                        call_stub_destroy(local->qstub);
                }
                if (local->fd) {
                        fd_unref(local->fd);
                }
                mem_put(local);
        }
        STACK_UNWIND_STRICT (lk, frame, -1, op_errno,
                             flock, xdata);
        return 0;
}

int32_t
jbr_lk_fan_in (call_frame_t *frame, void *cookie, xlator_t *this,
               int32_t op_ret, int32_t op_errno, struct gf_flock *flock,
               dict_t *xdata)
{
        uint8_t          call_count = -1;
        int32_t          ret        = -1;
        gf_boolean_t     result     = _gf_false;
        jbr_local_t     *local      = NULL;
        jbr_private_t   *priv       = NULL;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);
        GF_VALIDATE_OR_GOTO (this->name, frame, out);
        priv = this->private;
        local = frame->local;
        GF_VALIDATE_OR_GOTO (this->name, priv, out);
        GF_VALIDATE_OR_GOTO (this->name, local, out);

        gf_msg_trace (this->name, 0, "op_ret = %d, op_errno = %d\n",
                      op_ret, op_errno);

        LOCK(&frame->lock);
        call_count = --(local->call_count);
        if (op_ret != -1) {
                /* Increment the number of successful acks *
                 * received for the operation.             *
                 */
                (local->successful_acks)++;
                local->successful_op_ret = op_ret;
        }
        gf_msg_debug (this->name, 0, "succ_acks = %d, op_ret = %d, op_errno = %d\n",
                      op_ret, op_errno, local->successful_acks);
        UNLOCK(&frame->lock);

        if (call_count == 0) {
                /*
                 * If the fop is a locking fop, then check quorum. If quorum *
                 * is met, send successful ack to the client. If quorum is   *
                 * not met, then rollback locking on followers, followed by  *
                 * rollback of locking on leader, and then sending -ve ack   *
                 * to the client.                                            *
                 *                                                           *
                 * If the fop is a unlocking fop, then call stub.            *
                 */
                if (flock->l_type == F_UNLCK) {
                        call_resume(local->stub);
                } else {
                        /*
                         * Remove from queue for locking fops, for unlocking *
                         * fops, it is taken care of in jbr_lk_complete      *
                         */
                        ret = jbr_remove_from_queue (frame, this);
                        if (ret)
                                goto out;

                        fd_unref(local->fd);

                        result = fop_quorum_check (this,
                                          (double)priv->n_children,
                                          (double)local->successful_acks);
                        if (result == _gf_false) {
                                gf_msg (this->name, GF_LOG_ERROR, EROFS,
                                        J_MSG_QUORUM_NOT_MET,
                                        "Didn't receive enough acks to meet "
                                        "quorum. Failing the locking "
                                        "operation and initiating rollback on "
                                        "followers and the leader "
                                        "respectively.");

                                /* TODO: PERFORM ROLLBACK OF LOCKING ON
                                 * FOLLOWERS, FOLLOWED BY ROLLBACK ON
                                 * LEADER.
                                 */

                                STACK_UNWIND_STRICT (lk, frame, -1, EROFS,
                                                     flock, xdata);
                        } else {
                                STACK_UNWIND_STRICT (lk, frame, 0, 0,
                                                     flock, xdata);
                        }
                }
        }

        ret = 0;
out:
        return ret;
}

/*
 * Called from leader for locking fop, being writen as a separate *
 * function so as to support queues.                              *
 */
int32_t
jbr_perform_lk_on_leader (call_frame_t *frame, xlator_t *this,
                         fd_t *fd, int32_t cmd, struct gf_flock *flock,
                         dict_t *xdata)
{
        int32_t          ret    = -1;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);
        GF_VALIDATE_OR_GOTO (this->name, frame, out);
        GF_VALIDATE_OR_GOTO (this->name, flock, out);
        GF_VALIDATE_OR_GOTO (this->name, fd, out);

        STACK_WIND (frame, jbr_lk_complete,
                    FIRST_CHILD(this), FIRST_CHILD(this)->fops->lk,
                    fd, cmd, flock, xdata);

        ret = 0;
out:
        return ret;
}

int32_t
jbr_lk_perform_local_op (call_frame_t *frame, xlator_t *this, int *op_errno,
                         fd_t *fd, int32_t cmd, struct gf_flock *flock,
                         dict_t *xdata)
{
        int32_t          ret    = -1;
        jbr_local_t     *local  = NULL;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);
        GF_VALIDATE_OR_GOTO (this->name, frame, out);
        local = frame->local;
        GF_VALIDATE_OR_GOTO (this->name, local, out);
        GF_VALIDATE_OR_GOTO (this->name, fd, out);
        GF_VALIDATE_OR_GOTO (this->name, op_errno, out);
        GF_VALIDATE_OR_GOTO (this->name, flock, out);

        /*
         * Check if the fop is a locking fop or unlocking fop, and
         * handle it accordingly. If it is a locking fop, take the
         * lock on leader first, and then send it to the followers.
         * If it is a unlocking fop, unlock the followers first,
         * and then on meeting quorum perform the unlock on the leader.
         */
        if (flock->l_type == F_UNLCK) {
                ret = jbr_lk_call_dispatch (frame, this, op_errno,
                                            fd, cmd, flock, xdata);
                if (ret)
                        goto out;
        } else {
                jbr_inode_ctx_t  *ictx  = jbr_get_inode_ctx(this, fd->inode);

                if (!ictx) {
                        *op_errno = EIO;
                        goto out;
                }

                LOCK(&ictx->lock);
                        if (ictx->active) {
                                gf_msg_debug (this->name, 0,
                                              "queuing request due to conflict");

                                local->qstub = fop_lk_stub (frame,
                                                       jbr_perform_lk_on_leader,
                                                       fd, cmd, flock, xdata);
                                if (!local->qstub) {
                                        UNLOCK(&ictx->lock);
                                        goto out;
                                }
                                list_add_tail(&local->qlinks, &ictx->pqueue);
                                ++(ictx->pending);
                                UNLOCK(&ictx->lock);
                                ret = 0;
                                goto out;
                        } else {
                                list_add_tail(&local->qlinks, &ictx->aqueue);
                                ++(ictx->active);
                        }
                UNLOCK(&ictx->lock);
                ret = jbr_perform_lk_on_leader (frame, this, fd, cmd,
                                                flock, xdata);
        }

        ret = 0;
out:
        return ret;
}

int32_t
jbr_lk_continue (call_frame_t *frame, xlator_t *this,
                 fd_t *fd, int32_t cmd, struct gf_flock *flock, dict_t *xdata)
{
        int32_t          ret      = -1;
        jbr_local_t     *local    = NULL;
        jbr_private_t   *priv     = NULL;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);
        GF_VALIDATE_OR_GOTO (this->name, frame, out);
        priv = this->private;
        local = frame->local;
        GF_VALIDATE_OR_GOTO (this->name, priv, out);
        GF_VALIDATE_OR_GOTO (this->name, local, out);
        GF_VALIDATE_OR_GOTO (this->name, flock, out);
        GF_VALIDATE_OR_GOTO (this->name, fd, out);
        GF_VALIDATE_OR_GOTO (this->name, xdata, out);

        /*
         * If it's a locking fop, then call dispatch to followers  *
         * If it's a unlock fop, then perform the unlock operation *
         */
        if (flock->l_type == F_UNLCK) {
                STACK_WIND (frame, jbr_lk_complete,
                            FIRST_CHILD(this), FIRST_CHILD(this)->fops->lk,
                            fd, cmd, flock, xdata);
        } else {
                /*
                 * Directly call jbr_lk_dispatch instead of appending *
                 * in queue, which is done at jbr_lk_perform_local_op *
                 * for locking fops                                   *
                 */
                ret = jbr_lk_dispatch (frame, this, fd, cmd,
                                       flock, xdata);
                if (ret) {
                        STACK_UNWIND_STRICT (lk, frame, -1, 0,
                                             flock, xdata);
                        goto out;
                }
        }

        ret = 0;
out:
        return ret;
}

#pragma generate

uint8_t
jbr_count_up_kids (jbr_private_t *priv)
{
        uint8_t         retval  = 0;
        uint8_t         i;

        for (i = 0; i < priv->n_children; ++i) {
                if (priv->kid_state & (1 << i)) {
                        ++retval;
                }
        }

        return retval;
}

/*
 * The fsync machinery looks a lot like that for any write call, but there are
 * some important differences that are easy to miss.  First, we don't care
 * about the xdata that shows whether the call came from a leader or
 * reconciliation process.  If we're the leader we fan out; if we're not we
 * don't.  Second, we don't wait for followers before we issue the local call.
 * The code generation system could be updated to handle this, and still might
 * if we need to implement other "almost identical" paths (e.g. for open), but
 * a copy is more readable as long as it's just one.
 */

int32_t
jbr_fsync_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
               int32_t op_ret, int32_t op_errno, struct iatt *prebuf,
               struct iatt *postbuf, dict_t *xdata)
{
        jbr_local_t     *local  = frame->local;
        gf_boolean_t    unwind;

        LOCK(&frame->lock);
                unwind = !--(local->call_count);
        UNLOCK(&frame->lock);

        if (unwind) {
                STACK_UNWIND_STRICT (fsync, frame, op_ret, op_errno, prebuf,
                                     postbuf, xdata);
        }
        return 0;
}

int32_t
jbr_fsync_local_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
                     int32_t op_ret, int32_t op_errno, struct iatt *prebuf,
                     struct iatt *postbuf, dict_t *xdata)
{
        jbr_dirty_list_t        *dirty;
        jbr_dirty_list_t        *dtmp;
        jbr_local_t             *local  = frame->local;

        list_for_each_entry_safe (dirty, dtmp, &local->qlinks, links) {
                gf_msg_trace (this->name, 0,
                              "sending post-op on %p (%p)", local->fd, dirty);
                GF_FREE(dirty);
        }

        return jbr_fsync_cbk (frame, cookie, this, op_ret, op_errno,
                              prebuf, postbuf, xdata);
}

int32_t
jbr_fsync (call_frame_t *frame, xlator_t *this, fd_t *fd, int32_t flags,
           dict_t *xdata)
{
        jbr_private_t   *priv   = this->private;
        jbr_local_t     *local;
        uint64_t        ctx_int         = 0LL;
        jbr_fd_ctx_t    *ctx_ptr;
        xlator_list_t   *trav;

        local = mem_get0(this->local_pool);
        if (!local) {
                STACK_UNWIND_STRICT(fsync, frame, -1, ENOMEM,
                                    NULL, NULL, xdata);
                return 0;
        }
        INIT_LIST_HEAD(&local->qlinks);
        frame->local = local;

        /* Move the dirty list from the fd to the fsync request. */
        LOCK(&fd->lock);
                if (__fd_ctx_get(fd, this, &ctx_int) == 0) {
                        ctx_ptr = (jbr_fd_ctx_t *)(long)ctx_int;
                        list_splice_init (&ctx_ptr->dirty_list,
                                          &local->qlinks);
                }
        UNLOCK(&fd->lock);

        /* Issue the local call. */
        local->call_count = priv->leader ? priv->n_children : 1;
        STACK_WIND (frame, jbr_fsync_local_cbk,
                    FIRST_CHILD(this), FIRST_CHILD(this)->fops->fsync,
                    fd, flags, xdata);

        /* Issue remote calls if we're the leader. */
        if (priv->leader) {
                for (trav = this->children->next; trav; trav = trav->next) {
                        STACK_WIND (frame, jbr_fsync_cbk,
                                    FIRST_CHILD(this),
                                    FIRST_CHILD(this)->fops->fsync,
                                    fd, flags, xdata);
                }
        }

        return 0;
}

int32_t
jbr_getxattr_special (call_frame_t *frame, xlator_t *this, loc_t *loc,
                      const char *name, dict_t *xdata)
{
        dict_t          *result;
        jbr_private_t   *priv   = this->private;

        if (!priv->leader) {
                STACK_UNWIND_STRICT (getxattr, frame, -1, EREMOTE, NULL, NULL);
                return 0;
        }

        if (!name || (strcmp(name, JBR_REP_COUNT_XATTR) != 0)) {
                STACK_WIND_TAIL (frame,
                                 FIRST_CHILD(this),
                                 FIRST_CHILD(this)->fops->getxattr,
                                 loc, name, xdata);
                return 0;
        }

        result = dict_new();
        if (!result) {
                goto dn_failed;
        }

        priv->up_children = jbr_count_up_kids(this->private);
        if (dict_set_uint32(result, JBR_REP_COUNT_XATTR,
                            priv->up_children) != 0) {
                goto dsu_failed;
        }

        STACK_UNWIND_STRICT (getxattr, frame, 0, 0, result, NULL);
        dict_destroy(result);
        return 0;

dsu_failed:
        dict_destroy(result);
dn_failed:
        STACK_UNWIND_STRICT (getxattr, frame, -1, ENOMEM, NULL, NULL);
        return 0;
}

void
jbr_flush_fd (xlator_t *this, jbr_fd_ctx_t *fd_ctx)
{
        jbr_dirty_list_t        *dirty;
        jbr_dirty_list_t        *dtmp;

        list_for_each_entry_safe (dirty, dtmp, &fd_ctx->dirty_list, links) {
                gf_msg_trace (this->name, 0,
                              "sending post-op on %p (%p)", fd_ctx->fd, dirty);
                GF_FREE(dirty);
        }

        INIT_LIST_HEAD(&fd_ctx->dirty_list);
}

void *
jbr_flush_thread (void *ctx)
{
        xlator_t                *this   = ctx;
        jbr_private_t           *priv   = this->private;
        struct list_head        dirty_fds;
        jbr_fd_ctx_t            *fd_ctx;
        jbr_fd_ctx_t            *fd_tmp;
        int                     ret;

        for (;;) {
                /*
                 * We have to be very careful to avoid lock inversions here, so
                 * we can't just hold priv->dirty_lock while we take and
                 * release locks for each fd.  Instead, we only hold dirty_lock
                 * at the beginning of each iteration, as we (effectively) make
                 * a copy of the current list head and then clear the original.
                 * This leads to four scenarios for adding the first entry to
                 * an fd and potentially putting it on the global list.
                 *
                 * (1) While we're asleep.  No lock contention, it just gets
                 *     added and will be processed on the next iteration.
                 *
                 * (2) After we've made a local copy, but before we've started
                 *     processing that fd.  The new entry will be added to the
                 *     fd (under its lock), and we'll process it on the current
                 *     iteration.
                 *
                 * (3) While we're processing the fd.  They'll block on the fd
                 *     lock, then see that the list is empty and put it on the
                 *     global list.  We'll process it here on the next
                 *     iteration.
                 *
                 * (4) While we're working, but after we've processed that fd.
                 *     Same as (1) as far as that fd is concerned.
                 */
                INIT_LIST_HEAD(&dirty_fds);
                LOCK(&priv->dirty_lock);
                list_splice_init(&priv->dirty_fds, &dirty_fds);
                UNLOCK(&priv->dirty_lock);

                list_for_each_entry_safe (fd_ctx, fd_tmp, &dirty_fds, fd_list) {
                        ret = syncop_fsync(FIRST_CHILD(this), fd_ctx->fd, 0,
                                           NULL, NULL);
                        if (ret) {
                                gf_msg (this->name, GF_LOG_WARNING, 0,
                                        J_MSG_SYS_CALL_FAILURE,
                                        "failed to fsync %p (%d)",
                                        fd_ctx->fd, -ret);
                        }

                        LOCK(&fd_ctx->fd->lock);
                                jbr_flush_fd(this, fd_ctx);
                                list_del_init(&fd_ctx->fd_list);
                        UNLOCK(&fd_ctx->fd->lock);
                        fd_unref(fd_ctx->fd);
                }

                sleep(JBR_FLUSH_INTERVAL);
        }

        return NULL;
}


int32_t
jbr_get_changelog_dir (xlator_t *this, char **cl_dir_p)
{
        xlator_t        *cl_xl;

        /* Find our changelog translator. */
        cl_xl = this;
        while (cl_xl) {
                if (strcmp(cl_xl->type, "features/changelog") == 0) {
                        break;
                }
                cl_xl = cl_xl->children->xlator;
        }
        if (!cl_xl) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_INIT_FAIL,
                        "failed to find changelog translator");
                return ENOENT;
        }

        /* Find the actual changelog directory. */
        if (dict_get_str(cl_xl->options, "changelog-dir", cl_dir_p) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_INIT_FAIL,
                        "failed to find changelog-dir for %s", cl_xl->name);
                return ENODATA;
        }

        return 0;
}


void
jbr_get_terms (call_frame_t *frame, xlator_t *this)
{
        int32_t        op_errno      = 0;
        char          *cl_dir        = NULL;
        int32_t        term_first    = -1;
        int32_t        term_contig   = -1;
        int32_t        term_last     = -1;
        int            term_num      = 0;
        char          *probe_str     = NULL;
        dict_t        *my_xdata      = NULL;
        DIR           *fp            = NULL;
        struct dirent *entry         = NULL;
        struct dirent  scratch[2]    = {{0,},};

        op_errno = jbr_get_changelog_dir(this, &cl_dir);
        if (op_errno) {
                goto err;       /* Error was already logged. */
        }
        op_errno = ENODATA;     /* Most common error after this. */

        fp = sys_opendir (cl_dir);
        if (!fp) {
                op_errno = errno;
                goto err;
        }

        /* Find first and last terms. */
        for (;;) {
                errno = 0;
                entry = sys_readdir (fp, scratch);
                if (!entry || errno != 0) {
                        if (errno != 0) {
                                op_errno = errno;
                                goto err;
                        }
                        break;
                }

                if (fnmatch("TERM.*", entry->d_name, FNM_PATHNAME) != 0) {
                        continue;
                }
                /* +5 points to the character after the period */
                term_num = atoi(entry->d_name+5);
                gf_msg (this->name, GF_LOG_INFO, 0,
                        J_MSG_GENERIC,
                        "%s => %d", entry->d_name, term_num);
                if (term_num < 0) {
                        gf_msg (this->name, GF_LOG_ERROR, 0,
                                J_MSG_INVALID,
                                "invalid term file name %s", entry->d_name);
                        op_errno = EINVAL;
                        goto err;
                }
                if ((term_first < 0) || (term_first > term_num)) {
                        term_first = term_num;
                }
                if ((term_last < 0) || (term_last < term_num)) {
                        term_last = term_num;
                }
        }
        if ((term_first < 0) || (term_last < 0)) {
                /* TBD: are we *sure* there should always be at least one? */
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_NO_DATA, "no terms found");
                op_errno = EINVAL;
                goto err;
        }

        (void) sys_closedir (fp);
        fp = NULL;

        /*
         * Find term_contig, which is the earliest term for which there are
         * no gaps between it and term_last.
         */
        for (term_contig = term_last; term_contig > 0; --term_contig) {
                if (gf_asprintf(&probe_str, "%s/TERM.%d",
                                cl_dir, term_contig-1) <= 0) {
                        gf_msg (this->name, GF_LOG_ERROR, 0,
                                J_MSG_MEM_ERR,
                                "failed to format term %d", term_contig-1);
                        goto err;
                }
                if (sys_access(probe_str, F_OK) != 0) {
                        GF_FREE(probe_str);
                        break;
                }
                GF_FREE(probe_str);
        }

        gf_msg (this->name, GF_LOG_INFO, 0,
                J_MSG_GENERIC,
                "found terms %d-%d (%d)",
                term_first, term_last, term_contig);

        /* Return what we've found */
        my_xdata = dict_new();
        if (!my_xdata) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_MEM_ERR,
                        "failed to allocate reply dictionary");
                goto err;
        }
        if (dict_set_int32(my_xdata, "term-first", term_first) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_DICT_FLR,
                        "failed to set term-first");
                goto err;
        }
        if (dict_set_int32(my_xdata, "term-contig", term_contig) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_DICT_FLR,
                        "failed to set term-contig");
                goto err;
        }
        if (dict_set_int32(my_xdata, "term-last", term_last) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_DICT_FLR,
                        "failed to set term-last");
                goto err;
        }

        /* Finally! */
        STACK_UNWIND_STRICT (ipc, frame, 0, 0, my_xdata);
        dict_unref(my_xdata);
        return;

err:
        if (fp) {
                (void) sys_closedir (fp);
        }
        if (my_xdata) {
                dict_unref(my_xdata);
        }
        STACK_UNWIND_STRICT (ipc, frame, -1, op_errno, NULL);
}


long
get_entry_count (xlator_t *this, int fd)
{
        struct stat     buf;
        long            min;            /* last entry not known to be empty */
        long            max;            /* first entry known to be empty */
        long            curr;
        char            entry[CHANGELOG_ENTRY_SIZE];

        if (sys_fstat (fd, &buf) < 0) {
                return -1;
        }

        min = 0;
        max = buf.st_size / CHANGELOG_ENTRY_SIZE;

        while ((min+1) < max) {
                curr = (min + max) / 2;
                if (sys_lseek(fd, curr*CHANGELOG_ENTRY_SIZE, SEEK_SET) < 0) {
                        return -1;
                }
                if (sys_read(fd, entry, sizeof(entry)) != sizeof(entry)) {
                        return -1;
                }
                if ((entry[0] == '_') && (entry[1] == 'P')) {
                        min = curr;
                } else {
                        max = curr;
                }
        }

        if (sys_lseek(fd, 0, SEEK_SET) < 0) {
                gf_msg (this->name, GF_LOG_WARNING, 0,
                        J_MSG_SYS_CALL_FAILURE,
                        "failed to reset offset");
        }
        return max;
}


void
jbr_open_term (call_frame_t *frame, xlator_t *this, dict_t *xdata)
{
        int32_t         op_errno;
        char            *cl_dir;
        char            *term;
        char            *path;
        jbr_private_t   *priv           = this->private;

        op_errno = jbr_get_changelog_dir(this, &cl_dir);
        if (op_errno) {
                goto err;
        }

        if (dict_get_str(xdata, "term", &term) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_NO_DATA, "missing term");
                op_errno = ENODATA;
                goto err;
        }

        if (gf_asprintf(&path, "%s/TERM.%s", cl_dir, term) < 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_MEM_ERR, "failed to construct path");
                op_errno = ENOMEM;
                goto err;
        }

        if (priv->term_fd >= 0) {
                sys_close (priv->term_fd);
        }
        priv->term_fd = open(path, O_RDONLY);
        if (priv->term_fd < 0) {
                op_errno = errno;
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_SYS_CALL_FAILURE,
                        "failed to open term file");
                goto err;
        }

        priv->term_total = get_entry_count(this, priv->term_fd);
        if (priv->term_total < 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_NO_DATA, "failed to get entry count");
                sys_close (priv->term_fd);
                priv->term_fd = -1;
                op_errno = EIO;
                goto err;
        }
        priv->term_read = 0;

        /* Success! */
        STACK_UNWIND_STRICT (ipc, frame, 0, 0, NULL);
        return;

err:
        STACK_UNWIND_STRICT (ipc, frame, -1, op_errno, NULL);
}


void
jbr_next_entry (call_frame_t *frame, xlator_t *this)
{
        int32_t         op_errno        = ENOMEM;
        jbr_private_t   *priv           = this->private;
        ssize_t          nbytes;
        dict_t          *my_xdata;

        if (priv->term_fd < 0) {
                op_errno = EBADFD;
                goto err;
        }

        if (priv->term_read >= priv->term_total) {
                op_errno = ENODATA;
                goto err;
        }

        nbytes = sys_read (priv->term_fd, priv->term_buf, CHANGELOG_ENTRY_SIZE);
        if (nbytes < CHANGELOG_ENTRY_SIZE) {
                if (nbytes < 0) {
                        op_errno = errno;
                        gf_msg (this->name, GF_LOG_ERROR, 0,
                                J_MSG_SYS_CALL_FAILURE,
                                "error reading next entry: %s",
                                strerror(errno));
                } else {
                        op_errno = EIO;
                        gf_msg (this->name, GF_LOG_ERROR, 0,
                                J_MSG_SYS_CALL_FAILURE,
                                "got %zd/%d bytes for next entry",
                                nbytes, CHANGELOG_ENTRY_SIZE);
                }
                goto err;
        }
        ++(priv->term_read);

        my_xdata = dict_new();
        if (!my_xdata) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_MEM_ERR, "failed to allocate reply xdata");
                goto err;
        }

        if (dict_set_static_bin(my_xdata, "data",
                                priv->term_buf, CHANGELOG_ENTRY_SIZE) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0,
                        J_MSG_DICT_FLR, "failed to assign reply xdata");
                goto err;
        }

        STACK_UNWIND_STRICT (ipc, frame, 0, 0, my_xdata);
        dict_unref(my_xdata);
        return;

err:
        STACK_UNWIND_STRICT (ipc, frame, -1, op_errno, NULL);
}


int32_t
jbr_ipc (call_frame_t *frame, xlator_t *this, int32_t op, dict_t *xdata)
{
        switch (op) {
        case JBR_SERVER_TERM_RANGE:
                jbr_get_terms(frame, this);
                break;
        case JBR_SERVER_OPEN_TERM:
                jbr_open_term(frame, this, xdata);
                break;
        case JBR_SERVER_NEXT_ENTRY:
                jbr_next_entry(frame, this);
                break;
        default:
                STACK_WIND_TAIL (frame,
                                 FIRST_CHILD(this),
                                 FIRST_CHILD(this)->fops->ipc,
                                 op, xdata);
        }

        return 0;
}


int32_t
jbr_forget (xlator_t *this, inode_t *inode)
{
        uint64_t        ctx     = 0LL;

        if ((inode_ctx_del(inode, this, &ctx) == 0) && ctx) {
                GF_FREE((void *)(long)ctx);
        }

        return 0;
}

int32_t
jbr_release (xlator_t *this, fd_t *fd)
{
        uint64_t        ctx     = 0LL;

        if ((fd_ctx_del(fd, this, &ctx) == 0) && ctx) {
                GF_FREE((void *)(long)ctx);
        }

        return 0;
}

struct xlator_cbks cbks = {
        .forget  = jbr_forget,
        .release = jbr_release,
};

int
jbr_reconfigure (xlator_t *this, dict_t *options)
{
        jbr_private_t   *priv   = this->private;

        GF_OPTION_RECONF ("leader",
                          priv->config_leader, options, bool, err);
        GF_OPTION_RECONF ("quorum-percent",
                          priv->quorum_pct, options, percent, err);
        gf_msg (this->name, GF_LOG_INFO, 0, J_MSG_GENERIC,
                "reconfigure called, config_leader = %d, quorum_pct = %.1f\n",
                priv->leader, priv->quorum_pct);

        priv->leader = priv->config_leader;

        return 0;

err:
        return -1;
}

int
jbr_get_child_index (xlator_t *this, xlator_t *kid)
{
        xlator_list_t   *trav;
        int             retval = -1;

        for (trav = this->children; trav; trav = trav->next) {
                ++retval;
                if (trav->xlator == kid) {
                        return retval;
                }
        }

        return -1;
}

/*
 * Child notify handling is unreasonably FUBAR.  Sometimes we'll get a
 * CHILD_DOWN for a protocol/client child before we ever got a CHILD_UP for it.
 * Other times we won't.  Because it's effectively random (probably racy), we
 * can't just maintain a count.  We actually have to keep track of the state
 * for each child separately, to filter out the bogus CHILD_DOWN events, and
 * then generate counts on demand.
 */
int
jbr_notify (xlator_t *this, int event, void *data, ...)
{
        jbr_private_t   *priv         = this->private;
        int             index         = -1;
        int             ret           = -1;
        gf_boolean_t    result        = _gf_false;
        gf_boolean_t    relevant      = _gf_false;

        switch (event) {
        case GF_EVENT_CHILD_UP:
                index = jbr_get_child_index(this, data);
                if (index >= 0) {
                        /* Check if the child was previously down
                         * and it's not a false CHILD_UP
                         */
                        if (!(priv->kid_state & (1 << index))) {
                                relevant = _gf_true;
                        }

                        priv->kid_state |= (1 << index);
                        priv->up_children = jbr_count_up_kids(priv);
                        gf_msg (this->name, GF_LOG_INFO, 0, J_MSG_GENERIC,
                                "got CHILD_UP for %s, now %u kids",
                                ((xlator_t *)data)->name,
                                priv->up_children);
                        if (!priv->config_leader && (priv->up_children > 1)) {
                                priv->leader = _gf_false;
                        }

                        /* If it's not relevant, or we have already *
                         * sent CHILD_UP just break */
                        if (!relevant || priv->child_up)
                                break;

                        /* If it's not a leader, just send the notify up */
                        if (!priv->leader) {
                                ret = default_notify(this, event, data);
                                if (!ret)
                                        priv->child_up = _gf_true;
                                break;
                        }

                        result = fop_quorum_check (this,
                                                (double)(priv->n_children - 1),
                                               (double)(priv->up_children - 1));
                        if (result == _gf_false) {
                                gf_msg (this->name, GF_LOG_INFO, 0,
                                        J_MSG_GENERIC, "Not enough children "
                                        "are up to meet quorum. Waiting to "
                                        "send CHILD_UP from leader");
                        } else {
                                gf_msg (this->name, GF_LOG_INFO, 0,
                                        J_MSG_GENERIC, "Enough children are up "
                                        "to meet quorum. Sending CHILD_UP "
                                        "from leader");
                                ret = default_notify(this, event, data);
                                if (!ret)
                                        priv->child_up = _gf_true;
                        }
                }
                break;
        case GF_EVENT_CHILD_DOWN:
                index = jbr_get_child_index(this, data);
                if (index >= 0) {
                        /* Check if the child was previously up
                         * and it's not a false CHILD_DOWN
                         */
                        if (priv->kid_state & (1 << index)) {
                                relevant = _gf_true;
                        }
                        priv->kid_state &= ~(1 << index);
                        priv->up_children = jbr_count_up_kids(priv);
                        gf_msg (this->name, GF_LOG_INFO, 0, J_MSG_GENERIC,
                                "got CHILD_DOWN for %s, now %u kids",
                                ((xlator_t *)data)->name,
                                priv->up_children);
                        if (!priv->config_leader && (priv->up_children < 2)
                            && relevant) {
                                priv->leader = _gf_true;
                        }

                        /* If it's not relevant, or we have already *
                         * sent CHILD_DOWN just break */
                        if (!relevant || !priv->child_up)
                                break;

                        /* If it's not a leader, just break coz we shouldn't  *
                         * propagate the failure from the failure till it     *
                         * itself goes down                                   *
                         */
                        if (!priv->leader) {
                                break;
                        }

                        result = fop_quorum_check (this,
                                           (double)(priv->n_children - 1),
                                           (double)(priv->up_children - 1));
                        if (result == _gf_false) {
                                gf_msg (this->name, GF_LOG_INFO, 0,
                                        J_MSG_GENERIC, "Enough children are "
                                        "to down to fail quorum. "
                                        "Sending CHILD_DOWN from leader");
                                ret = default_notify(this, event, data);
                                if (!ret)
                                        priv->child_up = _gf_false;
                        } else {
                                gf_msg (this->name, GF_LOG_INFO, 0,
                                        J_MSG_GENERIC, "Not enough children "
                                        "are down to fail quorum. Waiting to "
                                        "send CHILD_DOWN from leader");
                        }
                }
                break;
        default:
                ret = default_notify(this, event, data);
        }

        return ret;
}


int32_t
mem_acct_init (xlator_t *this)
{
        int     ret = -1;

        GF_VALIDATE_OR_GOTO ("jbr", this, out);

        ret = xlator_mem_acct_init (this, gf_mt_jbr_end + 1);

        if (ret != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0, J_MSG_MEM_ERR,
                        "Memory accounting init" "failed");
                return ret;
        }
out:
        return ret;
}


void
jbr_deallocate_priv (jbr_private_t *priv)
{
        if (!priv) {
                return;
        }

        GF_FREE(priv);
}


int32_t
jbr_init (xlator_t *this)
{
        xlator_list_t   *remote;
        xlator_list_t   *local;
        jbr_private_t   *priv           = NULL;
        xlator_list_t   *trav;
        pthread_t       kid;
        extern xlator_t global_xlator;
        glusterfs_ctx_t *oldctx         = global_xlator.ctx;

        /*
         * Any fop that gets special treatment has to be patched in here,
         * because the compiled-in table is produced by the code generator and
         * only contains generated functions.  Note that we have to go through
         * this->fops because of some dynamic-linking strangeness; modifying
         * the static table doesn't work.
         */
        this->fops->getxattr = jbr_getxattr_special;
        this->fops->fsync = jbr_fsync;
        this->fops->ipc = jbr_ipc;

        local = this->children;
        if (!local) {
                gf_msg (this->name, GF_LOG_ERROR, 0, J_MSG_NO_DATA,
                        "no local subvolume");
                goto err;
        }

        remote = local->next;
        if (!remote) {
                gf_msg (this->name, GF_LOG_ERROR, 0, J_MSG_NO_DATA,
                        "no remote subvolumes");
                goto err;
        }

        this->local_pool = mem_pool_new (jbr_local_t, 128);
        if (!this->local_pool) {
                gf_msg (this->name, GF_LOG_ERROR, 0, J_MSG_MEM_ERR,
                        "failed to create jbr_local_t pool");
                goto err;
        }

        priv = GF_CALLOC (1, sizeof(*priv), gf_mt_jbr_private_t);
        if (!priv) {
                gf_msg (this->name, GF_LOG_ERROR, 0, J_MSG_MEM_ERR,
                        "could not allocate priv");
                goto err;
        }

        for (trav = this->children; trav; trav = trav->next) {
                ++(priv->n_children);
        }

        LOCK_INIT(&priv->dirty_lock);
	LOCK_INIT(&priv->index_lock);
        INIT_LIST_HEAD(&priv->dirty_fds);
        priv->term_fd = -1;

        this->private = priv;

        GF_OPTION_INIT ("leader", priv->config_leader, bool, err);
        GF_OPTION_INIT ("quorum-percent", priv->quorum_pct, percent, err);

        priv->leader = priv->config_leader;
        priv->child_up = _gf_false;

        if (pthread_create(&kid, NULL, jbr_flush_thread,
                           this) != 0) {
                gf_msg (this->name, GF_LOG_ERROR, 0, J_MSG_SYS_CALL_FAILURE,
                        "could not start flush thread");
                /* TBD: treat this as a fatal error? */
        }

        /*
         * Calling glfs_new changes old->ctx, even if THIS still points
         * to global_xlator.  That causes problems later in the main
         * thread, when gf_log_dump_graph tries to use the FILE after
         * we've mucked with it and gets a segfault in __fprintf_chk.
         * We can avoid all that by undoing the damage before we
         * continue.
         */
        global_xlator.ctx = oldctx;

	return 0;

err:
        jbr_deallocate_priv(priv);
        return -1;
}


void
jbr_fini (xlator_t *this)
{
        jbr_deallocate_priv(this->private);
}

class_methods_t class_methods = {
        .init           = jbr_init,
        .fini           = jbr_fini,
        .reconfigure    = jbr_reconfigure,
        .notify         = jbr_notify,
};

struct volume_options options[] = {
        { .key = {"leader"},
          .type = GF_OPTION_TYPE_BOOL,
          .default_value = "false",
          .description = "Start in the leader role.  This is only for "
                         "bootstrapping the code, and should go away when we "
                         "have real leader election."
        },
        { .key = {"vol-name"},
          .type = GF_OPTION_TYPE_STR,
          .description = "volume name"
        },
        { .key = {"my-name"},
          .type = GF_OPTION_TYPE_STR,
          .description = "brick name in form of host:/path"
        },
        { .key = {"etcd-servers"},
          .type = GF_OPTION_TYPE_STR,
          .description = "list of comma separated etc servers"
        },
        { .key = {"subvol-uuid"},
          .type = GF_OPTION_TYPE_STR,
          .description = "UUID for this JBR (sub)volume"
        },
        { .key = {"quorum-percent"},
          .type = GF_OPTION_TYPE_PERCENT,
          .default_value = "50.0",
          .description = "percentage of rep_count-1 that must be up"
        },
	{ .key = {NULL} },
};