summaryrefslogtreecommitdiffstats
path: root/fs/nfs/pnfs.c
blob: 17149a4900653af5326dfd6e0490e6e439b1426f (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
/*
 *  pNFS functions to call and manage layout drivers.
 *
 *  Copyright (c) 2002 [year of first publication]
 *  The Regents of the University of Michigan
 *  All Rights Reserved
 *
 *  Dean Hildebrand <dhildebz@umich.edu>
 *
 *  Permission is granted to use, copy, create derivative works, and
 *  redistribute this software and such derivative works for any purpose,
 *  so long as the name of the University of Michigan is not used in
 *  any advertising or publicity pertaining to the use or distribution
 *  of this software without specific, written prior authorization. If
 *  the above copyright notice or any other identification of the
 *  University of Michigan is included in any copy of any portion of
 *  this software, then the disclaimer below must also be included.
 *
 *  This software is provided as is, without representation or warranty
 *  of any kind either express or implied, including without limitation
 *  the implied warranties of merchantability, fitness for a particular
 *  purpose, or noninfringement.  The Regents of the University of
 *  Michigan shall not be liable for any damages, including special,
 *  indirect, incidental, or consequential damages, with respect to any
 *  claim arising out of or in connection with the use of the software,
 *  even if it has been or is hereafter advised of the possibility of
 *  such damages.
 */

#include <linux/nfs_fs.h>
#include <linux/nfs_page.h>
#include <linux/module.h>
#include "internal.h"
#include "pnfs.h"
#include "iostat.h"

#define NFSDBG_FACILITY		NFSDBG_PNFS

/* Locking:
 *
 * pnfs_spinlock:
 *      protects pnfs_modules_tbl.
 */
static DEFINE_SPINLOCK(pnfs_spinlock);

/*
 * pnfs_modules_tbl holds all pnfs modules
 */
static LIST_HEAD(pnfs_modules_tbl);

/* Return the registered pnfs layout driver module matching given id */
static struct pnfs_layoutdriver_type *
find_pnfs_driver_locked(u32 id)
{
	struct pnfs_layoutdriver_type *local;

	list_for_each_entry(local, &pnfs_modules_tbl, pnfs_tblid)
		if (local->id == id)
			goto out;
	local = NULL;
out:
	dprintk("%s: Searching for id %u, found %p\n", __func__, id, local);
	return local;
}

static struct pnfs_layoutdriver_type *
find_pnfs_driver(u32 id)
{
	struct pnfs_layoutdriver_type *local;

	spin_lock(&pnfs_spinlock);
	local = find_pnfs_driver_locked(id);
	spin_unlock(&pnfs_spinlock);
	return local;
}

void
unset_pnfs_layoutdriver(struct nfs_server *nfss)
{
	if (nfss->pnfs_curr_ld) {
		if (nfss->pnfs_curr_ld->clear_layoutdriver)
			nfss->pnfs_curr_ld->clear_layoutdriver(nfss);
		module_put(nfss->pnfs_curr_ld->owner);
	}
	nfss->pnfs_curr_ld = NULL;
}

/*
 * Try to set the server's pnfs module to the pnfs layout type specified by id.
 * Currently only one pNFS layout driver per filesystem is supported.
 *
 * @id layout type. Zero (illegal layout type) indicates pNFS not in use.
 */
void
set_pnfs_layoutdriver(struct nfs_server *server, const struct nfs_fh *mntfh,
		      u32 id)
{
	struct pnfs_layoutdriver_type *ld_type = NULL;

	if (id == 0)
		goto out_no_driver;
	if (!(server->nfs_client->cl_exchange_flags &
		 (EXCHGID4_FLAG_USE_NON_PNFS | EXCHGID4_FLAG_USE_PNFS_MDS))) {
		printk(KERN_ERR "%s: id %u cl_exchange_flags 0x%x\n", __func__,
		       id, server->nfs_client->cl_exchange_flags);
		goto out_no_driver;
	}
	ld_type = find_pnfs_driver(id);
	if (!ld_type) {
		request_module("%s-%u", LAYOUT_NFSV4_1_MODULE_PREFIX, id);
		ld_type = find_pnfs_driver(id);
		if (!ld_type) {
			dprintk("%s: No pNFS module found for %u.\n",
				__func__, id);
			goto out_no_driver;
		}
	}
	if (!try_module_get(ld_type->owner)) {
		dprintk("%s: Could not grab reference on module\n", __func__);
		goto out_no_driver;
	}
	server->pnfs_curr_ld = ld_type;
	if (ld_type->set_layoutdriver
	    && ld_type->set_layoutdriver(server, mntfh)) {
		printk(KERN_ERR "%s: Error initializing pNFS layout driver %u.\n",
				__func__, id);
		module_put(ld_type->owner);
		goto out_no_driver;
	}

	dprintk("%s: pNFS module for %u set\n", __func__, id);
	return;

out_no_driver:
	dprintk("%s: Using NFSv4 I/O\n", __func__);
	server->pnfs_curr_ld = NULL;
}

int
pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
{
	int status = -EINVAL;
	struct pnfs_layoutdriver_type *tmp;

	if (ld_type->id == 0) {
		printk(KERN_ERR "%s id 0 is reserved\n", __func__);
		return status;
	}
	if (!ld_type->alloc_lseg || !ld_type->free_lseg) {
		printk(KERN_ERR "%s Layout driver must provide "
		       "alloc_lseg and free_lseg.\n", __func__);
		return status;
	}

	spin_lock(&pnfs_spinlock);
	tmp = find_pnfs_driver_locked(ld_type->id);
	if (!tmp) {
		list_add(&ld_type->pnfs_tblid, &pnfs_modules_tbl);
		status = 0;
		dprintk("%s Registering id:%u name:%s\n", __func__, ld_type->id,
			ld_type->name);
	} else {
		printk(KERN_ERR "%s Module with id %d already loaded!\n",
			__func__, ld_type->id);
	}
	spin_unlock(&pnfs_spinlock);

	return status;
}
EXPORT_SYMBOL_GPL(pnfs_register_layoutdriver);

void
pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
{
	dprintk("%s Deregistering id:%u\n", __func__, ld_type->id);
	spin_lock(&pnfs_spinlock);
	list_del(&ld_type->pnfs_tblid);
	spin_unlock(&pnfs_spinlock);
}
EXPORT_SYMBOL_GPL(pnfs_unregister_layoutdriver);

/*
 * pNFS client layout cache
 */

/* Need to hold i_lock if caller does not already hold reference */
void
get_layout_hdr(struct pnfs_layout_hdr *lo)
{
	atomic_inc(&lo->plh_refcount);
}

static struct pnfs_layout_hdr *
pnfs_alloc_layout_hdr(struct inode *ino, gfp_t gfp_flags)
{
	struct pnfs_layoutdriver_type *ld = NFS_SERVER(ino)->pnfs_curr_ld;
	return ld->alloc_layout_hdr ? ld->alloc_layout_hdr(ino, gfp_flags) :
		kzalloc(sizeof(struct pnfs_layout_hdr), gfp_flags);
}

static void
pnfs_free_layout_hdr(struct pnfs_layout_hdr *lo)
{
	struct pnfs_layoutdriver_type *ld = NFS_SERVER(lo->plh_inode)->pnfs_curr_ld;
	put_rpccred(lo->plh_lc_cred);
	return ld->alloc_layout_hdr ? ld->free_layout_hdr(lo) : kfree(lo);
}

static void
destroy_layout_hdr(struct pnfs_layout_hdr *lo)
{
	dprintk("%s: freeing layout cache %p\n", __func__, lo);
	BUG_ON(!list_empty(&lo->plh_layouts));
	NFS_I(lo->plh_inode)->layout = NULL;
	pnfs_free_layout_hdr(lo);
}

static void
put_layout_hdr_locked(struct pnfs_layout_hdr *lo)
{
	if (atomic_dec_and_test(&lo->plh_refcount))
		destroy_layout_hdr(lo);
}

void
put_layout_hdr(struct pnfs_layout_hdr *lo)
{
	struct inode *inode = lo->plh_inode;

	if (atomic_dec_and_lock(&lo->plh_refcount, &inode->i_lock)) {
		destroy_layout_hdr(lo);
		spin_unlock(&inode->i_lock);
	}
}

static void
init_lseg(struct pnfs_layout_hdr *lo, struct pnfs_layout_segment *lseg)
{
	INIT_LIST_HEAD(&lseg->pls_list);
	INIT_LIST_HEAD(&lseg->pls_lc_list);
	atomic_set(&lseg->pls_refcount, 1);
	smp_mb();
	set_bit(NFS_LSEG_VALID, &lseg->pls_flags);
	lseg->pls_layout = lo;
}

static void free_lseg(struct pnfs_layout_segment *lseg)
{
	struct inode *ino = lseg->pls_layout->plh_inode;

	NFS_SERVER(ino)->pnfs_curr_ld->free_lseg(lseg);
	/* Matched by get_layout_hdr in pnfs_insert_layout */
	put_layout_hdr(NFS_I(ino)->layout);
}

static void
put_lseg_common(struct pnfs_layout_segment *lseg)
{
	struct inode *inode = lseg->pls_layout->plh_inode;

	WARN_ON(test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
	list_del_init(&lseg->pls_list);
	if (list_empty(&lseg->pls_layout->plh_segs)) {
		set_bit(NFS_LAYOUT_DESTROYED, &lseg->pls_layout->plh_flags);
		/* Matched by initial refcount set in alloc_init_layout_hdr */
		put_layout_hdr_locked(lseg->pls_layout);
	}
	rpc_wake_up(&NFS_SERVER(inode)->roc_rpcwaitq);
}

void
put_lseg(struct pnfs_layout_segment *lseg)
{
	struct inode *inode;

	if (!lseg)
		return;

	dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg,
		atomic_read(&lseg->pls_refcount),
		test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
	inode = lseg->pls_layout->plh_inode;
	if (atomic_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
		LIST_HEAD(free_me);

		put_lseg_common(lseg);
		list_add(&lseg->pls_list, &free_me);
		spin_unlock(&inode->i_lock);
		pnfs_free_lseg_list(&free_me);
	}
}
EXPORT_SYMBOL_GPL(put_lseg);

static inline u64
end_offset(u64 start, u64 len)
{
	u64 end;

	end = start + len;
	return end >= start ? end : NFS4_MAX_UINT64;
}

/* last octet in a range */
static inline u64
last_byte_offset(u64 start, u64 len)
{
	u64 end;

	BUG_ON(!len);
	end = start + len;
	return end > start ? end - 1 : NFS4_MAX_UINT64;
}

/*
 * is l2 fully contained in l1?
 *   start1                             end1
 *   [----------------------------------)
 *           start2           end2
 *           [----------------)
 */
static inline int
lo_seg_contained(struct pnfs_layout_range *l1,
		 struct pnfs_layout_range *l2)
{
	u64 start1 = l1->offset;
	u64 end1 = end_offset(start1, l1->length);
	u64 start2 = l2->offset;
	u64 end2 = end_offset(start2, l2->length);

	return (start1 <= start2) && (end1 >= end2);
}

/*
 * is l1 and l2 intersecting?
 *   start1                             end1
 *   [----------------------------------)
 *                              start2           end2
 *                              [----------------)
 */
static inline int
lo_seg_intersecting(struct pnfs_layout_range *l1,
		    struct pnfs_layout_range *l2)
{
	u64 start1 = l1->offset;
	u64 end1 = end_offset(start1, l1->length);
	u64 start2 = l2->offset;
	u64 end2 = end_offset(start2, l2->length);

	return (end1 == NFS4_MAX_UINT64 || end1 > start2) &&
	       (end2 == NFS4_MAX_UINT64 || end2 > start1);
}

static bool
should_free_lseg(struct pnfs_layout_range *lseg_range,
		 struct pnfs_layout_range *recall_range)
{
	return (recall_range->iomode == IOMODE_ANY ||
		lseg_range->iomode == recall_range->iomode) &&
	       lo_seg_intersecting(lseg_range, recall_range);
}

/* Returns 1 if lseg is removed from list, 0 otherwise */
static int mark_lseg_invalid(struct pnfs_layout_segment *lseg,
			     struct list_head *tmp_list)
{
	int rv = 0;

	if (test_and_clear_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
		/* Remove the reference keeping the lseg in the
		 * list.  It will now be removed when all
		 * outstanding io is finished.
		 */
		dprintk("%s: lseg %p ref %d\n", __func__, lseg,
			atomic_read(&lseg->pls_refcount));
		if (atomic_dec_and_test(&lseg->pls_refcount)) {
			put_lseg_common(lseg);
			list_add(&lseg->pls_list, tmp_list);
			rv = 1;
		}
	}
	return rv;
}

/* Returns count of number of matching invalid lsegs remaining in list
 * after call.
 */
int
mark_matching_lsegs_invalid(struct pnfs_layout_hdr *lo,
			    struct list_head *tmp_list,
			    struct pnfs_layout_range *recall_range)
{
	struct pnfs_layout_segment *lseg, *next;
	int invalid = 0, removed = 0;

	dprintk("%s:Begin lo %p\n", __func__, lo);

	if (list_empty(&lo->plh_segs)) {
		if (!test_and_set_bit(NFS_LAYOUT_DESTROYED, &lo->plh_flags))
			put_layout_hdr_locked(lo);
		return 0;
	}
	list_for_each_entry_safe(lseg, next, &lo->plh_segs, pls_list)
		if (!recall_range ||
		    should_free_lseg(&lseg->pls_range, recall_range)) {
			dprintk("%s: freeing lseg %p iomode %d "
				"offset %llu length %llu\n", __func__,
				lseg, lseg->pls_range.iomode, lseg->pls_range.offset,
				lseg->pls_range.length);
			invalid++;
			removed += mark_lseg_invalid(lseg, tmp_list);
		}
	dprintk("%s:Return %i\n", __func__, invalid - removed);
	return invalid - removed;
}

/* note free_me must contain lsegs from a single layout_hdr */
void
pnfs_free_lseg_list(struct list_head *free_me)
{
	struct pnfs_layout_segment *lseg, *tmp;
	struct pnfs_layout_hdr *lo;

	if (list_empty(free_me))
		return;

	lo = list_first_entry(free_me, struct pnfs_layout_segment,
			      pls_list)->pls_layout;

	if (test_bit(NFS_LAYOUT_DESTROYED, &lo->plh_flags)) {
		struct nfs_client *clp;

		clp = NFS_SERVER(lo->plh_inode)->nfs_client;
		spin_lock(&clp->cl_lock);
		list_del_init(&lo->plh_layouts);
		spin_unlock(&clp->cl_lock);
	}
	list_for_each_entry_safe(lseg, tmp, free_me, pls_list) {
		list_del(&lseg->pls_list);
		free_lseg(lseg);
	}
}

void
pnfs_destroy_layout(struct nfs_inode *nfsi)
{
	struct pnfs_layout_hdr *lo;
	LIST_HEAD(tmp_list);

	spin_lock(&nfsi->vfs_inode.i_lock);
	lo = nfsi->layout;
	if (lo) {
		lo->plh_block_lgets++; /* permanently block new LAYOUTGETs */
		mark_matching_lsegs_invalid(lo, &tmp_list, NULL);
	}
	spin_unlock(&nfsi->vfs_inode.i_lock);
	pnfs_free_lseg_list(&tmp_list);
}

/*
 * Called by the state manger to remove all layouts established under an
 * expired lease.
 */
void
pnfs_destroy_all_layouts(struct nfs_client *clp)
{
	struct nfs_server *server;
	struct pnfs_layout_hdr *lo;
	LIST_HEAD(tmp_list);

	nfs4_deviceid_mark_client_invalid(clp);
	nfs4_deviceid_purge_client(clp);

	spin_lock(&clp->cl_lock);
	rcu_read_lock();
	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
		if (!list_empty(&server->layouts))
			list_splice_init(&server->layouts, &tmp_list);
	}
	rcu_read_unlock();
	spin_unlock(&clp->cl_lock);

	while (!list_empty(&tmp_list)) {
		lo = list_entry(tmp_list.next, struct pnfs_layout_hdr,
				plh_layouts);
		dprintk("%s freeing layout for inode %lu\n", __func__,
			lo->plh_inode->i_ino);
		list_del_init(&lo->plh_layouts);
		pnfs_destroy_layout(NFS_I(lo->plh_inode));
	}
}

/* update lo->plh_stateid with new if is more recent */
void
pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo, const nfs4_stateid *new,
			bool update_barrier)
{
	u32 oldseq, newseq;

	oldseq = be32_to_cpu(lo->plh_stateid.stateid.seqid);
	newseq = be32_to_cpu(new->stateid.seqid);
	if ((int)(newseq - oldseq) > 0) {
		memcpy(&lo->plh_stateid, &new->stateid, sizeof(new->stateid));
		if (update_barrier) {
			u32 new_barrier = be32_to_cpu(new->stateid.seqid);

			if ((int)(new_barrier - lo->plh_barrier))
				lo->plh_barrier = new_barrier;
		} else {
			/* Because of wraparound, we want to keep the barrier
			 * "close" to the current seqids.  It needs to be
			 * within 2**31 to count as "behind", so if it
			 * gets too near that limit, give us a litle leeway
			 * and bring it to within 2**30.
			 * NOTE - and yes, this is all unsigned arithmetic.
			 */
			if (unlikely((newseq - lo->plh_barrier) > (3 << 29)))
				lo->plh_barrier = newseq - (1 << 30);
		}
	}
}

/* lget is set to 1 if called from inside send_layoutget call chain */
static bool
pnfs_layoutgets_blocked(struct pnfs_layout_hdr *lo, nfs4_stateid *stateid,
			int lget)
{
	if ((stateid) &&
	    (int)(lo->plh_barrier - be32_to_cpu(stateid->stateid.seqid)) >= 0)
		return true;
	return lo->plh_block_lgets ||
		test_bit(NFS_LAYOUT_DESTROYED, &lo->plh_flags) ||
		test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags) ||
		(list_empty(&lo->plh_segs) &&
		 (atomic_read(&lo->plh_outstanding) > lget));
}

int
pnfs_choose_layoutget_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo,
			      struct nfs4_state *open_state)
{
	int status = 0;

	dprintk("--> %s\n", __func__);
	spin_lock(&lo->plh_inode->i_lock);
	if (pnfs_layoutgets_blocked(lo, NULL, 1)) {
		status = -EAGAIN;
	} else if (list_empty(&lo->plh_segs)) {
		int seq;

		do {
			seq = read_seqbegin(&open_state->seqlock);
			memcpy(dst->data, open_state->stateid.data,
			       sizeof(open_state->stateid.data));
		} while (read_seqretry(&open_state->seqlock, seq));
	} else
		memcpy(dst->data, lo->plh_stateid.data, sizeof(lo->plh_stateid.data));
	spin_unlock(&lo->plh_inode->i_lock);
	dprintk("<-- %s\n", __func__);
	return status;
}

/*
* Get layout from server.
*    for now, assume that whole file layouts are requested.
*    arg->offset: 0
*    arg->length: all ones
*/
static struct pnfs_layout_segment *
send_layoutget(struct pnfs_layout_hdr *lo,
	   struct nfs_open_context *ctx,
	   struct pnfs_layout_range *range,
	   gfp_t gfp_flags)
{
	struct inode *ino = lo->plh_inode;
	struct nfs_server *server = NFS_SERVER(ino);
	struct nfs4_layoutget *lgp;
	struct pnfs_layout_segment *lseg = NULL;
	struct page **pages = NULL;
	int i;
	u32 max_resp_sz, max_pages;

	dprintk("--> %s\n", __func__);

	BUG_ON(ctx == NULL);
	lgp = kzalloc(sizeof(*lgp), gfp_flags);
	if (lgp == NULL)
		return NULL;

	/* allocate pages for xdr post processing */
	max_resp_sz = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
	max_pages = max_resp_sz >> PAGE_SHIFT;

	pages = kzalloc(max_pages * sizeof(struct page *), gfp_flags);
	if (!pages)
		goto out_err_free;

	for (i = 0; i < max_pages; i++) {
		pages[i] = alloc_page(gfp_flags);
		if (!pages[i])
			goto out_err_free;
	}

	lgp->args.minlength = PAGE_CACHE_SIZE;
	if (lgp->args.minlength > range->length)
		lgp->args.minlength = range->length;
	lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
	lgp->args.range = *range;
	lgp->args.type = server->pnfs_curr_ld->id;
	lgp->args.inode = ino;
	lgp->args.ctx = get_nfs_open_context(ctx);
	lgp->args.layout.pages = pages;
	lgp->args.layout.pglen = max_pages * PAGE_SIZE;
	lgp->lsegpp = &lseg;
	lgp->gfp_flags = gfp_flags;

	/* Synchronously retrieve layout information from server and
	 * store in lseg.
	 */
	nfs4_proc_layoutget(lgp);
	if (!lseg) {
		/* remember that LAYOUTGET failed and suspend trying */
		set_bit(lo_fail_bit(range->iomode), &lo->plh_flags);
	}

	/* free xdr pages */
	for (i = 0; i < max_pages; i++)
		__free_page(pages[i]);
	kfree(pages);

	return lseg;

out_err_free:
	/* free any allocated xdr pages, lgp as it's not used */
	if (pages) {
		for (i = 0; i < max_pages; i++) {
			if (!pages[i])
				break;
			__free_page(pages[i]);
		}
		kfree(pages);
	}
	kfree(lgp);
	return NULL;
}

/* Initiates a LAYOUTRETURN(FILE) */
int
_pnfs_return_layout(struct inode *ino)
{
	struct pnfs_layout_hdr *lo = NULL;
	struct nfs_inode *nfsi = NFS_I(ino);
	LIST_HEAD(tmp_list);
	struct nfs4_layoutreturn *lrp;
	nfs4_stateid stateid;
	int status = 0;

	dprintk("--> %s\n", __func__);

	spin_lock(&ino->i_lock);
	lo = nfsi->layout;
	if (!lo) {
		spin_unlock(&ino->i_lock);
		dprintk("%s: no layout to return\n", __func__);
		return status;
	}
	stateid = nfsi->layout->plh_stateid;
	/* Reference matched in nfs4_layoutreturn_release */
	get_layout_hdr(lo);
	mark_matching_lsegs_invalid(lo, &tmp_list, NULL);
	lo->plh_block_lgets++;
	spin_unlock(&ino->i_lock);
	pnfs_free_lseg_list(&tmp_list);

	WARN_ON(test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags));

	lrp = kzalloc(sizeof(*lrp), GFP_KERNEL);
	if (unlikely(lrp == NULL)) {
		status = -ENOMEM;
		set_bit(NFS_LAYOUT_RW_FAILED, &lo->plh_flags);
		set_bit(NFS_LAYOUT_RO_FAILED, &lo->plh_flags);
		put_layout_hdr(lo);
		goto out;
	}

	lrp->args.stateid = stateid;
	lrp->args.layout_type = NFS_SERVER(ino)->pnfs_curr_ld->id;
	lrp->args.inode = ino;
	lrp->args.layout = lo;
	lrp->clp = NFS_SERVER(ino)->nfs_client;

	status = nfs4_proc_layoutreturn(lrp);
out:
	dprintk("<-- %s status: %d\n", __func__, status);
	return status;
}

bool pnfs_roc(struct inode *ino)
{
	struct pnfs_layout_hdr *lo;
	struct pnfs_layout_segment *lseg, *tmp;
	LIST_HEAD(tmp_list);
	bool found = false;

	spin_lock(&ino->i_lock);
	lo = NFS_I(ino)->layout;
	if (!lo || !test_and_clear_bit(NFS_LAYOUT_ROC, &lo->plh_flags) ||
	    test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags))
		goto out_nolayout;
	list_for_each_entry_safe(lseg, tmp, &lo->plh_segs, pls_list)
		if (test_bit(NFS_LSEG_ROC, &lseg->pls_flags)) {
			mark_lseg_invalid(lseg, &tmp_list);
			found = true;
		}
	if (!found)
		goto out_nolayout;
	lo->plh_block_lgets++;
	get_layout_hdr(lo); /* matched in pnfs_roc_release */
	spin_unlock(&ino->i_lock);
	pnfs_free_lseg_list(&tmp_list);
	return true;

out_nolayout:
	spin_unlock(&ino->i_lock);
	return false;
}

void pnfs_roc_release(struct inode *ino)
{
	struct pnfs_layout_hdr *lo;

	spin_lock(&ino->i_lock);
	lo = NFS_I(ino)->layout;
	lo->plh_block_lgets--;
	put_layout_hdr_locked(lo);
	spin_unlock(&ino->i_lock);
}

void pnfs_roc_set_barrier(struct inode *ino, u32 barrier)
{
	struct pnfs_layout_hdr *lo;

	spin_lock(&ino->i_lock);
	lo = NFS_I(ino)->layout;
	if ((int)(barrier - lo->plh_barrier) > 0)
		lo->plh_barrier = barrier;
	spin_unlock(&ino->i_lock);
}

bool pnfs_roc_drain(struct inode *ino, u32 *barrier)
{
	struct nfs_inode *nfsi = NFS_I(ino);
	struct pnfs_layout_segment *lseg;
	bool found = false;

	spin_lock(&ino->i_lock);
	list_for_each_entry(lseg, &nfsi->layout->plh_segs, pls_list)
		if (test_bit(NFS_LSEG_ROC, &lseg->pls_flags)) {
			found = true;
			break;
		}
	if (!found) {
		struct pnfs_layout_hdr *lo = nfsi->layout;
		u32 current_seqid = be32_to_cpu(lo->plh_stateid.stateid.seqid);

		/* Since close does not return a layout stateid for use as
		 * a barrier, we choose the worst-case barrier.
		 */
		*barrier = current_seqid + atomic_read(&lo->plh_outstanding);
	}
	spin_unlock(&ino->i_lock);
	return found;
}

/*
 * Compare two layout segments for sorting into layout cache.
 * We want to preferentially return RW over RO layouts, so ensure those
 * are seen first.
 */
static s64
cmp_layout(struct pnfs_layout_range *l1,
	   struct pnfs_layout_range *l2)
{
	s64 d;

	/* high offset > low offset */
	d = l1->offset - l2->offset;
	if (d)
		return d;

	/* short length > long length */
	d = l2->length - l1->length;
	if (d)
		return d;

	/* read > read/write */
	return (int)(l1->iomode == IOMODE_READ) - (int)(l2->iomode == IOMODE_READ);
}

static void
pnfs_insert_layout(struct pnfs_layout_hdr *lo,
		   struct pnfs_layout_segment *lseg)
{
	struct pnfs_layout_segment *lp;

	dprintk("%s:Begin\n", __func__);

	assert_spin_locked(&lo->plh_inode->i_lock);
	list_for_each_entry(lp, &lo->plh_segs, pls_list) {
		if (cmp_layout(&lseg->pls_range, &lp->pls_range) > 0)
			continue;
		list_add_tail(&lseg->pls_list, &lp->pls_list);
		dprintk("%s: inserted lseg %p "
			"iomode %d offset %llu length %llu before "
			"lp %p iomode %d offset %llu length %llu\n",
			__func__, lseg, lseg->pls_range.iomode,
			lseg->pls_range.offset, lseg->pls_range.length,
			lp, lp->pls_range.iomode, lp->pls_range.offset,
			lp->pls_range.length);
		goto out;
	}
	list_add_tail(&lseg->pls_list, &lo->plh_segs);
	dprintk("%s: inserted lseg %p "
		"iomode %d offset %llu length %llu at tail\n",
		__func__, lseg, lseg->pls_range.iomode,
		lseg->pls_range.offset, lseg->pls_range.length);
out:
	get_layout_hdr(lo);

	dprintk("%s:Return\n", __func__);
}

static struct pnfs_layout_hdr *
alloc_init_layout_hdr(struct inode *ino,
		      struct nfs_open_context *ctx,
		      gfp_t gfp_flags)
{
	struct pnfs_layout_hdr *lo;

	lo = pnfs_alloc_layout_hdr(ino, gfp_flags);
	if (!lo)
		return NULL;
	atomic_set(&lo->plh_refcount, 1);
	INIT_LIST_HEAD(&lo->plh_layouts);
	INIT_LIST_HEAD(&lo->plh_segs);
	INIT_LIST_HEAD(&lo->plh_bulk_recall);
	lo->plh_inode = ino;
	lo->plh_lc_cred = get_rpccred(ctx->state->owner->so_cred);
	return lo;
}

static struct pnfs_layout_hdr *
pnfs_find_alloc_layout(struct inode *ino,
		       struct nfs_open_context *ctx,
		       gfp_t gfp_flags)
{
	struct nfs_inode *nfsi = NFS_I(ino);
	struct pnfs_layout_hdr *new = NULL;

	dprintk("%s Begin ino=%p layout=%p\n", __func__, ino, nfsi->layout);

	assert_spin_locked(&ino->i_lock);
	if (nfsi->layout) {
		if (test_bit(NFS_LAYOUT_DESTROYED, &nfsi->layout->plh_flags))
			return NULL;
		else
			return nfsi->layout;
	}
	spin_unlock(&ino->i_lock);
	new = alloc_init_layout_hdr(ino, ctx, gfp_flags);
	spin_lock(&ino->i_lock);

	if (likely(nfsi->layout == NULL))	/* Won the race? */
		nfsi->layout = new;
	else
		pnfs_free_layout_hdr(new);
	return nfsi->layout;
}

/*
 * iomode matching rules:
 * iomode	lseg	match
 * -----	-----	-----
 * ANY		READ	true
 * ANY		RW	true
 * RW		READ	false
 * RW		RW	true
 * READ		READ	true
 * READ		RW	true
 */
static int
is_matching_lseg(struct pnfs_layout_range *ls_range,
		 struct pnfs_layout_range *range)
{
	struct pnfs_layout_range range1;

	if ((range->iomode == IOMODE_RW &&
	     ls_range->iomode != IOMODE_RW) ||
	    !lo_seg_intersecting(ls_range, range))
		return 0;

	/* range1 covers only the first byte in the range */
	range1 = *range;
	range1.length = 1;
	return lo_seg_contained(ls_range, &range1);
}

/*
 * lookup range in layout
 */
static struct pnfs_layout_segment *
pnfs_find_lseg(struct pnfs_layout_hdr *lo,
		struct pnfs_layout_range *range)
{
	struct pnfs_layout_segment *lseg, *ret = NULL;

	dprintk("%s:Begin\n", __func__);

	assert_spin_locked(&lo->plh_inode->i_lock);
	list_for_each_entry(lseg, &lo->plh_segs, pls_list) {
		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags) &&
		    is_matching_lseg(&lseg->pls_range, range)) {
			ret = get_lseg(lseg);
			break;
		}
		if (lseg->pls_range.offset > range->offset)
			break;
	}

	dprintk("%s:Return lseg %p ref %d\n",
		__func__, ret, ret ? atomic_read(&ret->pls_refcount) : 0);
	return ret;
}

/*
 * Layout segment is retreived from the server if not cached.
 * The appropriate layout segment is referenced and returned to the caller.
 */
struct pnfs_layout_segment *
pnfs_update_layout(struct inode *ino,
		   struct nfs_open_context *ctx,
		   loff_t pos,
		   u64 count,
		   enum pnfs_iomode iomode,
		   gfp_t gfp_flags)
{
	struct pnfs_layout_range arg = {
		.iomode = iomode,
		.offset = pos,
		.length = count,
	};
	unsigned pg_offset;
	struct nfs_inode *nfsi = NFS_I(ino);
	struct nfs_server *server = NFS_SERVER(ino);
	struct nfs_client *clp = server->nfs_client;
	struct pnfs_layout_hdr *lo;
	struct pnfs_layout_segment *lseg = NULL;
	bool first = false;

	if (!pnfs_enabled_sb(NFS_SERVER(ino)))
		return NULL;
	spin_lock(&ino->i_lock);
	lo = pnfs_find_alloc_layout(ino, ctx, gfp_flags);
	if (lo == NULL) {
		dprintk("%s ERROR: can't get pnfs_layout_hdr\n", __func__);
		goto out_unlock;
	}

	/* Do we even need to bother with this? */
	if (test_bit(NFS4CLNT_LAYOUTRECALL, &clp->cl_state) ||
	    test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
		dprintk("%s matches recall, use MDS\n", __func__);
		goto out_unlock;
	}

	/* if LAYOUTGET already failed once we don't try again */
	if (test_bit(lo_fail_bit(iomode), &nfsi->layout->plh_flags))
		goto out_unlock;

	/* Check to see if the layout for the given range already exists */
	lseg = pnfs_find_lseg(lo, &arg);
	if (lseg)
		goto out_unlock;

	if (pnfs_layoutgets_blocked(lo, NULL, 0))
		goto out_unlock;
	atomic_inc(&lo->plh_outstanding);

	get_layout_hdr(lo);
	if (list_empty(&lo->plh_segs))
		first = true;
	spin_unlock(&ino->i_lock);
	if (first) {
		/* The lo must be on the clp list if there is any
		 * chance of a CB_LAYOUTRECALL(FILE) coming in.
		 */
		spin_lock(&clp->cl_lock);
		BUG_ON(!list_empty(&lo->plh_layouts));
		list_add_tail(&lo->plh_layouts, &server->layouts);
		spin_unlock(&clp->cl_lock);
	}

	pg_offset = arg.offset & ~PAGE_CACHE_MASK;
	if (pg_offset) {
		arg.offset -= pg_offset;
		arg.length += pg_offset;
	}
	if (arg.length != NFS4_MAX_UINT64)
		arg.length = PAGE_CACHE_ALIGN(arg.length);

	lseg = send_layoutget(lo, ctx, &arg, gfp_flags);
	if (!lseg && first) {
		spin_lock(&clp->cl_lock);
		list_del_init(&lo->plh_layouts);
		spin_unlock(&clp->cl_lock);
	}
	atomic_dec(&lo->plh_outstanding);
	put_layout_hdr(lo);
out:
	dprintk("%s end, state 0x%lx lseg %p\n", __func__,
		nfsi->layout ? nfsi->layout->plh_flags : -1, lseg);
	return lseg;
out_unlock:
	spin_unlock(&ino->i_lock);
	goto out;
}
EXPORT_SYMBOL_GPL(pnfs_update_layout);

int
pnfs_layout_process(struct nfs4_layoutget *lgp)
{
	struct pnfs_layout_hdr *lo = NFS_I(lgp->args.inode)->layout;
	struct nfs4_layoutget_res *res = &lgp->res;
	struct pnfs_layout_segment *lseg;
	struct inode *ino = lo->plh_inode;
	struct nfs_client *clp = NFS_SERVER(ino)->nfs_client;
	int status = 0;

	/* Inject layout blob into I/O device driver */
	lseg = NFS_SERVER(ino)->pnfs_curr_ld->alloc_lseg(lo, res, lgp->gfp_flags);
	if (!lseg || IS_ERR(lseg)) {
		if (!lseg)
			status = -ENOMEM;
		else
			status = PTR_ERR(lseg);
		dprintk("%s: Could not allocate layout: error %d\n",
		       __func__, status);
		goto out;
	}

	spin_lock(&ino->i_lock);
	if (test_bit(NFS4CLNT_LAYOUTRECALL, &clp->cl_state) ||
	    test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
		dprintk("%s forget reply due to recall\n", __func__);
		goto out_forget_reply;
	}

	if (pnfs_layoutgets_blocked(lo, &res->stateid, 1)) {
		dprintk("%s forget reply due to state\n", __func__);
		goto out_forget_reply;
	}
	init_lseg(lo, lseg);
	lseg->pls_range = res->range;
	*lgp->lsegpp = get_lseg(lseg);
	pnfs_insert_layout(lo, lseg);

	if (res->return_on_close) {
		set_bit(NFS_LSEG_ROC, &lseg->pls_flags);
		set_bit(NFS_LAYOUT_ROC, &lo->plh_flags);
	}

	/* Done processing layoutget. Set the layout stateid */
	pnfs_set_layout_stateid(lo, &res->stateid, false);
	spin_unlock(&ino->i_lock);
out:
	return status;

out_forget_reply:
	spin_unlock(&ino->i_lock);
	lseg->pls_layout = lo;
	NFS_SERVER(ino)->pnfs_curr_ld->free_lseg(lseg);
	goto out;
}

void
pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
{
	BUG_ON(pgio->pg_lseg != NULL);

	pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
					   req->wb_context,
					   req_offset(req),
					   req->wb_bytes,
					   IOMODE_READ,
					   GFP_KERNEL);
	/* If no lseg, fall back to read through mds */
	if (pgio->pg_lseg == NULL)
		nfs_pageio_reset_read_mds(pgio);

}
EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_read);

void
pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
{
	BUG_ON(pgio->pg_lseg != NULL);

	pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
					   req->wb_context,
					   req_offset(req),
					   req->wb_bytes,
					   IOMODE_RW,
					   GFP_NOFS);
	/* If no lseg, fall back to write through mds */
	if (pgio->pg_lseg == NULL)
		nfs_pageio_reset_write_mds(pgio);
}
EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_write);

bool
pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode)
{
	struct nfs_server *server = NFS_SERVER(inode);
	struct pnfs_layoutdriver_type *ld = server->pnfs_curr_ld;

	if (ld == NULL)
		return false;
	nfs_pageio_init(pgio, inode, ld->pg_read_ops, server->rsize, 0);
	return true;
}

bool
pnfs_pageio_init_write(struct nfs_pageio_descriptor *pgio, struct inode *inode, int ioflags)
{
	struct nfs_server *server = NFS_SERVER(inode);
	struct pnfs_layoutdriver_type *ld = server->pnfs_curr_ld;

	if (ld == NULL)
		return false;
	nfs_pageio_init(pgio, inode, ld->pg_write_ops, server->wsize, ioflags);
	return true;
}

bool
pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
		     struct nfs_page *req)
{
	if (pgio->pg_lseg == NULL)
		return nfs_generic_pg_test(pgio, prev, req);

	/*
	 * Test if a nfs_page is fully contained in the pnfs_layout_range.
	 * Note that this test makes several assumptions:
	 * - that the previous nfs_page in the struct nfs_pageio_descriptor
	 *   is known to lie within the range.
	 *   - that the nfs_page being tested is known to be contiguous with the
	 *   previous nfs_page.
	 *   - Layout ranges are page aligned, so we only have to test the
	 *   start offset of the request.
	 *
	 * Please also note that 'end_offset' is actually the offset of the
	 * first byte that lies outside the pnfs_layout_range. FIXME?
	 *
	 */
	return req_offset(req) < end_offset(pgio->pg_lseg->pls_range.offset,
					 pgio->pg_lseg->pls_range.length);
}
EXPORT_SYMBOL_GPL(pnfs_generic_pg_test);

static int pnfs_write_done_resend_to_mds(struct inode *inode, struct list_head *head)
{
	struct nfs_pageio_descriptor pgio;
	LIST_HEAD(failed);

	/* Resend all requests through the MDS */
	nfs_pageio_init_write_mds(&pgio, inode, FLUSH_STABLE);
	while (!list_empty(head)) {
		struct nfs_page *req = nfs_list_entry(head->next);

		nfs_list_remove_request(req);
		if (!nfs_pageio_add_request(&pgio, req))
			nfs_list_add_request(req, &failed);
	}
	nfs_pageio_complete(&pgio);

	if (!list_empty(&failed)) {
		/* For some reason our attempt to resend pages. Mark the
		 * overall send request as having failed, and let
		 * nfs_writeback_release_full deal with the error.
		 */
		list_move(&failed, head);
		return -EIO;
	}
	return 0;
}

/*
 * Called by non rpc-based layout drivers
 */
void pnfs_ld_write_done(struct nfs_write_data *data)
{
	if (likely(!data->pnfs_error)) {
		pnfs_set_layoutcommit(data);
		data->mds_ops->rpc_call_done(&data->task, data);
	} else {
		dprintk("pnfs write error = %d\n", data->pnfs_error);
		if (NFS_SERVER(data->inode)->pnfs_curr_ld->flags &
						PNFS_LAYOUTRET_ON_ERROR) {
			/* Don't lo_commit on error, Server will needs to
			 * preform a file recovery.
			 */
			clear_bit(NFS_INO_LAYOUTCOMMIT,
				  &NFS_I(data->inode)->flags);
			pnfs_return_layout(data->inode);
		}
		data->task.tk_status = pnfs_write_done_resend_to_mds(data->inode, &data->pages);
	}
	data->mds_ops->rpc_release(data);
}
EXPORT_SYMBOL_GPL(pnfs_ld_write_done);

static void
pnfs_write_through_mds(struct nfs_pageio_descriptor *desc,
		struct nfs_write_data *data)
{
	list_splice_tail_init(&data->pages, &desc->pg_list);
	if (data->req && list_empty(&data->req->wb_list))
		nfs_list_add_request(data->req, &desc->pg_list);
	nfs_pageio_reset_write_mds(desc);
	desc->pg_recoalesce = 1;
	nfs_writedata_release(data);
}

static enum pnfs_try_status
pnfs_try_to_write_data(struct nfs_write_data *wdata,
			const struct rpc_call_ops *call_ops,
			struct pnfs_layout_segment *lseg,
			int how)
{
	struct inode *inode = wdata->inode;
	enum pnfs_try_status trypnfs;
	struct nfs_server *nfss = NFS_SERVER(inode);

	wdata->mds_ops = call_ops;
	wdata->lseg = get_lseg(lseg);

	dprintk("%s: Writing ino:%lu %u@%llu (how %d)\n", __func__,
		inode->i_ino, wdata->args.count, wdata->args.offset, how);

	trypnfs = nfss->pnfs_curr_ld->write_pagelist(wdata, how);
	if (trypnfs == PNFS_NOT_ATTEMPTED) {
		put_lseg(wdata->lseg);
		wdata->lseg = NULL;
	} else
		nfs_inc_stats(inode, NFSIOS_PNFS_WRITE);

	dprintk("%s End (trypnfs:%d)\n", __func__, trypnfs);
	return trypnfs;
}

static void
pnfs_do_multiple_writes(struct nfs_pageio_descriptor *desc, struct list_head *head, int how)
{
	struct nfs_write_data *data;
	const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
	struct pnfs_layout_segment *lseg = desc->pg_lseg;

	desc->pg_lseg = NULL;
	while (!list_empty(head)) {
		enum pnfs_try_status trypnfs;

		data = list_entry(head->next, struct nfs_write_data, list);
		list_del_init(&data->list);

		trypnfs = pnfs_try_to_write_data(data, call_ops, lseg, how);
		if (trypnfs == PNFS_NOT_ATTEMPTED)
			pnfs_write_through_mds(desc, data);
	}
	put_lseg(lseg);
}

int
pnfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
{
	LIST_HEAD(head);
	int ret;

	ret = nfs_generic_flush(desc, &head);
	if (ret != 0) {
		put_lseg(desc->pg_lseg);
		desc->pg_lseg = NULL;
		return ret;
	}
	pnfs_do_multiple_writes(desc, &head, desc->pg_ioflags);
	return 0;
}
EXPORT_SYMBOL_GPL(pnfs_generic_pg_writepages);

static void pnfs_ld_handle_read_error(struct nfs_read_data *data)
{
	struct nfs_pageio_descriptor pgio;

	put_lseg(data->lseg);
	data->lseg = NULL;
	dprintk("pnfs write error = %d\n", data->pnfs_error);
	if (NFS_SERVER(data->inode)->pnfs_curr_ld->flags &
						PNFS_LAYOUTRET_ON_ERROR)
		pnfs_return_layout(data->inode);

	nfs_pageio_init_read_mds(&pgio, data->inode);

	while (!list_empty(&data->pages)) {
		struct nfs_page *req = nfs_list_entry(data->pages.next);

		nfs_list_remove_request(req);
		nfs_pageio_add_request(&pgio, req);
	}
	nfs_pageio_complete(&pgio);
}

/*
 * Called by non rpc-based layout drivers
 */
void pnfs_ld_read_done(struct nfs_read_data *data)
{
	if (likely(!data->pnfs_error)) {
		__nfs4_read_done_cb(data);
		data->mds_ops->rpc_call_done(&data->task, data);
	} else
		pnfs_ld_handle_read_error(data);
	data->mds_ops->rpc_release(data);
}
EXPORT_SYMBOL_GPL(pnfs_ld_read_done);

static void
pnfs_read_through_mds(struct nfs_pageio_descriptor *desc,
		struct nfs_read_data *data)
{
	list_splice_tail_init(&data->pages, &desc->pg_list);
	if (data->req && list_empty(&data->req->wb_list))
		nfs_list_add_request(data->req, &desc->pg_list);
	nfs_pageio_reset_read_mds(desc);
	desc->pg_recoalesce = 1;
	nfs_readdata_release(data);
}

/*
 * Call the appropriate parallel I/O subsystem read function.
 */
static enum pnfs_try_status
pnfs_try_to_read_data(struct nfs_read_data *rdata,
		       const struct rpc_call_ops *call_ops,
		       struct pnfs_layout_segment *lseg)
{
	struct inode *inode = rdata->inode;
	struct nfs_server *nfss = NFS_SERVER(inode);
	enum pnfs_try_status trypnfs;

	rdata->mds_ops = call_ops;
	rdata->lseg = get_lseg(lseg);

	dprintk("%s: Reading ino:%lu %u@%llu\n",
		__func__, inode->i_ino, rdata->args.count, rdata->args.offset);

	trypnfs = nfss->pnfs_curr_ld->read_pagelist(rdata);
	if (trypnfs == PNFS_NOT_ATTEMPTED) {
		put_lseg(rdata->lseg);
		rdata->lseg = NULL;
	} else {
		nfs_inc_stats(inode, NFSIOS_PNFS_READ);
	}
	dprintk("%s End (trypnfs:%d)\n", __func__, trypnfs);
	return trypnfs;
}

static void
pnfs_do_multiple_reads(struct nfs_pageio_descriptor *desc, struct list_head *head)
{
	struct nfs_read_data *data;
	const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
	struct pnfs_layout_segment *lseg = desc->pg_lseg;

	desc->pg_lseg = NULL;
	while (!list_empty(head)) {
		enum pnfs_try_status trypnfs;

		data = list_entry(head->next, struct nfs_read_data, list);
		list_del_init(&data->list);

		trypnfs = pnfs_try_to_read_data(data, call_ops, lseg);
		if (trypnfs == PNFS_NOT_ATTEMPTED)
			pnfs_read_through_mds(desc, data);
	}
	put_lseg(lseg);
}

int
pnfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
{
	LIST_HEAD(head);
	int ret;

	ret = nfs_generic_pagein(desc, &head);
	if (ret != 0) {
		put_lseg(desc->pg_lseg);
		desc->pg_lseg = NULL;
		return ret;
	}
	pnfs_do_multiple_reads(desc, &head);
	return 0;
}
EXPORT_SYMBOL_GPL(pnfs_generic_pg_readpages);

/*
 * There can be multiple RW segments.
 */
static void pnfs_list_write_lseg(struct inode *inode, struct list_head *listp)
{
	struct pnfs_layout_segment *lseg;

	list_for_each_entry(lseg, &NFS_I(inode)->layout->plh_segs, pls_list) {
		if (lseg->pls_range.iomode == IOMODE_RW &&
		    test_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))
			list_add(&lseg->pls_lc_list, listp);
	}
}

void pnfs_set_lo_fail(struct pnfs_layout_segment *lseg)
{
	if (lseg->pls_range.iomode == IOMODE_RW) {
		dprintk("%s Setting layout IOMODE_RW fail bit\n", __func__);
		set_bit(lo_fail_bit(IOMODE_RW), &lseg->pls_layout->plh_flags);
	} else {
		dprintk("%s Setting layout IOMODE_READ fail bit\n", __func__);
		set_bit(lo_fail_bit(IOMODE_READ), &lseg->pls_layout->plh_flags);
	}
}
EXPORT_SYMBOL_GPL(pnfs_set_lo_fail);

void
pnfs_set_layoutcommit(struct nfs_write_data *wdata)
{
	struct nfs_inode *nfsi = NFS_I(wdata->inode);
	loff_t end_pos = wdata->mds_offset + wdata->res.count;
	bool mark_as_dirty = false;

	spin_lock(&nfsi->vfs_inode.i_lock);
	if (!test_and_set_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags)) {
		mark_as_dirty = true;
		dprintk("%s: Set layoutcommit for inode %lu ",
			__func__, wdata->inode->i_ino);
	}
	if (!test_and_set_bit(NFS_LSEG_LAYOUTCOMMIT, &wdata->lseg->pls_flags)) {
		/* references matched in nfs4_layoutcommit_release */
		get_lseg(wdata->lseg);
	}
	if (end_pos > nfsi->layout->plh_lwb)
		nfsi->layout->plh_lwb = end_pos;
	spin_unlock(&nfsi->vfs_inode.i_lock);
	dprintk("%s: lseg %p end_pos %llu\n",
		__func__, wdata->lseg, nfsi->layout->plh_lwb);

	/* if pnfs_layoutcommit_inode() runs between inode locks, the next one
	 * will be a noop because NFS_INO_LAYOUTCOMMIT will not be set */
	if (mark_as_dirty)
		mark_inode_dirty_sync(wdata->inode);
}
EXPORT_SYMBOL_GPL(pnfs_set_layoutcommit);

void pnfs_cleanup_layoutcommit(struct nfs4_layoutcommit_data *data)
{
	struct nfs_server *nfss = NFS_SERVER(data->args.inode);

	if (nfss->pnfs_curr_ld->cleanup_layoutcommit)
		nfss->pnfs_curr_ld->cleanup_layoutcommit(data);
}

/*
 * For the LAYOUT4_NFSV4_1_FILES layout type, NFS_DATA_SYNC WRITEs and
 * NFS_UNSTABLE WRITEs with a COMMIT to data servers must store enough
 * data to disk to allow the server to recover the data if it crashes.
 * LAYOUTCOMMIT is only needed when the NFL4_UFLG_COMMIT_THRU_MDS flag
 * is off, and a COMMIT is sent to a data server, or
 * if WRITEs to a data server return NFS_DATA_SYNC.
 */
int
pnfs_layoutcommit_inode(struct inode *inode, bool sync)
{
	struct nfs4_layoutcommit_data *data;
	struct nfs_inode *nfsi = NFS_I(inode);
	loff_t end_pos;
	int status = 0;

	dprintk("--> %s inode %lu\n", __func__, inode->i_ino);

	if (!test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags))
		return 0;

	/* Note kzalloc ensures data->res.seq_res.sr_slot == NULL */
	data = kzalloc(sizeof(*data), GFP_NOFS);
	if (!data) {
		status = -ENOMEM;
		goto out;
	}

	if (!test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags))
		goto out_free;

	if (test_and_set_bit(NFS_INO_LAYOUTCOMMITTING, &nfsi->flags)) {
		if (!sync) {
			status = -EAGAIN;
			goto out_free;
		}
		status = wait_on_bit_lock(&nfsi->flags, NFS_INO_LAYOUTCOMMITTING,
					nfs_wait_bit_killable, TASK_KILLABLE);
		if (status)
			goto out_free;
	}

	INIT_LIST_HEAD(&data->lseg_list);
	spin_lock(&inode->i_lock);
	if (!test_and_clear_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags)) {
		clear_bit(NFS_INO_LAYOUTCOMMITTING, &nfsi->flags);
		spin_unlock(&inode->i_lock);
		wake_up_bit(&nfsi->flags, NFS_INO_LAYOUTCOMMITTING);
		goto out_free;
	}

	pnfs_list_write_lseg(inode, &data->lseg_list);

	end_pos = nfsi->layout->plh_lwb;
	nfsi->layout->plh_lwb = 0;

	memcpy(&data->args.stateid.data, nfsi->layout->plh_stateid.data,
		sizeof(nfsi->layout->plh_stateid.data));
	spin_unlock(&inode->i_lock);

	data->args.inode = inode;
	data->cred = get_rpccred(nfsi->layout->plh_lc_cred);
	nfs_fattr_init(&data->fattr);
	data->args.bitmask = NFS_SERVER(inode)->cache_consistency_bitmask;
	data->res.fattr = &data->fattr;
	data->args.lastbytewritten = end_pos - 1;
	data->res.server = NFS_SERVER(inode);

	status = nfs4_proc_layoutcommit(data, sync);
out:
	if (status)
		mark_inode_dirty_sync(inode);
	dprintk("<-- %s status %d\n", __func__, status);
	return status;
out_free:
	kfree(data);
	goto out;
}