summaryrefslogtreecommitdiffstats
path: root/fs/nfs/blocklayout/extents.c
blob: 1abac09f7cd5f9fd46cc07401873067e49a4b7f7 (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
/*
 *  linux/fs/nfs/blocklayout/blocklayout.h
 *
 *  Module for the NFSv4.1 pNFS block layout driver.
 *
 *  Copyright (c) 2006 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson <andros@citi.umich.edu>
 *  Fred Isaman <iisaman@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 from the
 * university of michigan as to its fitness for any purpose, and without
 * warranty by the university of michigan of any kind, either express
 * or implied, including without limitation the implied warranties of
 * merchantability and fitness for a particular purpose.  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 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 "blocklayout.h"
#define NFSDBG_FACILITY         NFSDBG_PNFS_LD

/* Bit numbers */
#define EXTENT_INITIALIZED 0
#define EXTENT_WRITTEN     1
#define EXTENT_IN_COMMIT   2
#define INTERNAL_EXISTS    MY_MAX_TAGS
#define INTERNAL_MASK      ((1 << INTERNAL_EXISTS) - 1)

/* Returns largest t<=s s.t. t%base==0 */
static inline sector_t normalize(sector_t s, int base)
{
	sector_t tmp = s; /* Since do_div modifies its argument */
	return s - do_div(tmp, base);
}

static inline sector_t normalize_up(sector_t s, int base)
{
	return normalize(s + base - 1, base);
}

/* Complete stub using list while determine API wanted */

/* Returns tags, or negative */
static int32_t _find_entry(struct my_tree *tree, u64 s)
{
	struct pnfs_inval_tracking *pos;

	dprintk("%s(%llu) enter\n", __func__, s);
	list_for_each_entry_reverse(pos, &tree->mtt_stub, it_link) {
		if (pos->it_sector > s)
			continue;
		else if (pos->it_sector == s)
			return pos->it_tags & INTERNAL_MASK;
		else
			break;
	}
	return -ENOENT;
}

static inline
int _has_tag(struct my_tree *tree, u64 s, int32_t tag)
{
	int32_t tags;

	dprintk("%s(%llu, %i) enter\n", __func__, s, tag);
	s = normalize(s, tree->mtt_step_size);
	tags = _find_entry(tree, s);
	if ((tags < 0) || !(tags & (1 << tag)))
		return 0;
	else
		return 1;
}

/* Creates entry with tag, or if entry already exists, unions tag to it.
 * If storage is not NULL, newly created entry will use it.
 * Returns number of entries added, or negative on error.
 */
static int _add_entry(struct my_tree *tree, u64 s, int32_t tag,
		      struct pnfs_inval_tracking *storage)
{
	int found = 0;
	struct pnfs_inval_tracking *pos;

	dprintk("%s(%llu, %i, %p) enter\n", __func__, s, tag, storage);
	list_for_each_entry_reverse(pos, &tree->mtt_stub, it_link) {
		if (pos->it_sector > s)
			continue;
		else if (pos->it_sector == s) {
			found = 1;
			break;
		} else
			break;
	}
	if (found) {
		pos->it_tags |= (1 << tag);
		return 0;
	} else {
		struct pnfs_inval_tracking *new;
		new = storage;
		new->it_sector = s;
		new->it_tags = (1 << tag);
		list_add(&new->it_link, &pos->it_link);
		return 1;
	}
}

/* XXXX Really want option to not create */
/* Over range, unions tag with existing entries, else creates entry with tag */
static int _set_range(struct my_tree *tree, int32_t tag, u64 s, u64 length)
{
	u64 i;

	dprintk("%s(%i, %llu, %llu) enter\n", __func__, tag, s, length);
	for (i = normalize(s, tree->mtt_step_size); i < s + length;
	     i += tree->mtt_step_size)
		if (_add_entry(tree, i, tag, NULL))
			return -ENOMEM;
	return 0;
}

/* Ensure that future operations on given range of tree will not malloc */
static int _preload_range(struct pnfs_inval_markings *marks,
		u64 offset, u64 length)
{
	u64 start, end, s;
	int count, i, used = 0, status = -ENOMEM;
	struct pnfs_inval_tracking **storage;
	struct my_tree  *tree = &marks->im_tree;

	dprintk("%s(%llu, %llu) enter\n", __func__, offset, length);
	start = normalize(offset, tree->mtt_step_size);
	end = normalize_up(offset + length, tree->mtt_step_size);
	count = (int)(end - start) / (int)tree->mtt_step_size;

	/* Pre-malloc what memory we might need */
	storage = kmalloc(sizeof(*storage) * count, GFP_NOFS);
	if (!storage)
		return -ENOMEM;
	for (i = 0; i < count; i++) {
		storage[i] = kmalloc(sizeof(struct pnfs_inval_tracking),
				     GFP_NOFS);
		if (!storage[i])
			goto out_cleanup;
	}

	spin_lock_bh(&marks->im_lock);
	for (s = start; s < end; s += tree->mtt_step_size)
		used += _add_entry(tree, s, INTERNAL_EXISTS, storage[used]);
	spin_unlock_bh(&marks->im_lock);

	status = 0;

 out_cleanup:
	for (i = used; i < count; i++) {
		if (!storage[i])
			break;
		kfree(storage[i]);
	}
	kfree(storage);
	return status;
}

/* We are relying on page lock to serialize this */
int bl_is_sector_init(struct pnfs_inval_markings *marks, sector_t isect)
{
	int rv;

	spin_lock_bh(&marks->im_lock);
	rv = _has_tag(&marks->im_tree, isect, EXTENT_INITIALIZED);
	spin_unlock_bh(&marks->im_lock);
	return rv;
}

/* Assume start, end already sector aligned */
static int
_range_has_tag(struct my_tree *tree, u64 start, u64 end, int32_t tag)
{
	struct pnfs_inval_tracking *pos;
	u64 expect = 0;

	dprintk("%s(%llu, %llu, %i) enter\n", __func__, start, end, tag);
	list_for_each_entry_reverse(pos, &tree->mtt_stub, it_link) {
		if (pos->it_sector >= end)
			continue;
		if (!expect) {
			if ((pos->it_sector == end - tree->mtt_step_size) &&
			    (pos->it_tags & (1 << tag))) {
				expect = pos->it_sector - tree->mtt_step_size;
				if (pos->it_sector < tree->mtt_step_size || expect < start)
					return 1;
				continue;
			} else {
				return 0;
			}
		}
		if (pos->it_sector != expect || !(pos->it_tags & (1 << tag)))
			return 0;
		expect -= tree->mtt_step_size;
		if (expect < start)
			return 1;
	}
	return 0;
}

static int is_range_written(struct pnfs_inval_markings *marks,
			    sector_t start, sector_t end)
{
	int rv;

	spin_lock_bh(&marks->im_lock);
	rv = _range_has_tag(&marks->im_tree, start, end, EXTENT_WRITTEN);
	spin_unlock_bh(&marks->im_lock);
	return rv;
}

/* Marks sectors in [offest, offset_length) as having been initialized.
 * All lengths are step-aligned, where step is min(pagesize, blocksize).
 * Currently assumes offset is page-aligned
 */
int bl_mark_sectors_init(struct pnfs_inval_markings *marks,
			     sector_t offset, sector_t length)
{
	sector_t start, end;

	dprintk("%s(offset=%llu,len=%llu) enter\n",
		__func__, (u64)offset, (u64)length);

	start = normalize(offset, marks->im_block_size);
	end = normalize_up(offset + length, marks->im_block_size);
	if (_preload_range(marks, start, end - start))
		goto outerr;

	spin_lock_bh(&marks->im_lock);
	if (_set_range(&marks->im_tree, EXTENT_INITIALIZED, offset, length))
		goto out_unlock;
	spin_unlock_bh(&marks->im_lock);

	return 0;

out_unlock:
	spin_unlock_bh(&marks->im_lock);
outerr:
	return -ENOMEM;
}

/* Marks sectors in [offest, offset+length) as having been written to disk.
 * All lengths should be block aligned.
 */
static int mark_written_sectors(struct pnfs_inval_markings *marks,
				sector_t offset, sector_t length)
{
	int status;

	dprintk("%s(offset=%llu,len=%llu) enter\n", __func__,
		(u64)offset, (u64)length);
	spin_lock_bh(&marks->im_lock);
	status = _set_range(&marks->im_tree, EXTENT_WRITTEN, offset, length);
	spin_unlock_bh(&marks->im_lock);
	return status;
}

static void print_short_extent(struct pnfs_block_short_extent *be)
{
	dprintk("PRINT SHORT EXTENT extent %p\n", be);
	if (be) {
		dprintk("        be_f_offset %llu\n", (u64)be->bse_f_offset);
		dprintk("        be_length   %llu\n", (u64)be->bse_length);
	}
}

static void print_clist(struct list_head *list, unsigned int count)
{
	struct pnfs_block_short_extent *be;
	unsigned int i = 0;

	ifdebug(FACILITY) {
		printk(KERN_DEBUG "****************\n");
		printk(KERN_DEBUG "Extent list looks like:\n");
		list_for_each_entry(be, list, bse_node) {
			i++;
			print_short_extent(be);
		}
		if (i != count)
			printk(KERN_DEBUG "\n\nExpected %u entries\n\n\n", count);
		printk(KERN_DEBUG "****************\n");
	}
}

/* Note: In theory, we should do more checking that devid's match between
 * old and new, but if they don't, the lists are too corrupt to salvage anyway.
 */
/* Note this is very similar to bl_add_merge_extent */
static void add_to_commitlist(struct pnfs_block_layout *bl,
			      struct pnfs_block_short_extent *new)
{
	struct list_head *clist = &bl->bl_commit;
	struct pnfs_block_short_extent *old, *save;
	sector_t end = new->bse_f_offset + new->bse_length;

	dprintk("%s enter\n", __func__);
	print_short_extent(new);
	print_clist(clist, bl->bl_count);
	bl->bl_count++;
	/* Scan for proper place to insert, extending new to the left
	 * as much as possible.
	 */
	list_for_each_entry_safe(old, save, clist, bse_node) {
		if (new->bse_f_offset < old->bse_f_offset)
			break;
		if (end <= old->bse_f_offset + old->bse_length) {
			/* Range is already in list */
			bl->bl_count--;
			kfree(new);
			return;
		} else if (new->bse_f_offset <=
				old->bse_f_offset + old->bse_length) {
			/* new overlaps or abuts existing be */
			if (new->bse_mdev == old->bse_mdev) {
				/* extend new to fully replace old */
				new->bse_length += new->bse_f_offset -
						old->bse_f_offset;
				new->bse_f_offset = old->bse_f_offset;
				list_del(&old->bse_node);
				bl->bl_count--;
				kfree(old);
			}
		}
	}
	/* Note that if we never hit the above break, old will not point to a
	 * valid extent.  However, in that case &old->bse_node==list.
	 */
	list_add_tail(&new->bse_node, &old->bse_node);
	/* Scan forward for overlaps.  If we find any, extend new and
	 * remove the overlapped extent.
	 */
	old = list_prepare_entry(new, clist, bse_node);
	list_for_each_entry_safe_continue(old, save, clist, bse_node) {
		if (end < old->bse_f_offset)
			break;
		/* new overlaps or abuts old */
		if (new->bse_mdev == old->bse_mdev) {
			if (end < old->bse_f_offset + old->bse_length) {
				/* extend new to fully cover old */
				end = old->bse_f_offset + old->bse_length;
				new->bse_length = end - new->bse_f_offset;
			}
			list_del(&old->bse_node);
			bl->bl_count--;
			kfree(old);
		}
	}
	dprintk("%s: after merging\n", __func__);
	print_clist(clist, bl->bl_count);
}

/* Note the range described by offset, length is guaranteed to be contained
 * within be.
 * new will be freed, either by this function or add_to_commitlist if they
 * decide not to use it, or after LAYOUTCOMMIT uses it in the commitlist.
 */
int bl_mark_for_commit(struct pnfs_block_extent *be,
		    sector_t offset, sector_t length,
		    struct pnfs_block_short_extent *new)
{
	sector_t new_end, end = offset + length;
	struct pnfs_block_layout *bl = container_of(be->be_inval,
						    struct pnfs_block_layout,
						    bl_inval);

	mark_written_sectors(be->be_inval, offset, length);
	/* We want to add the range to commit list, but it must be
	 * block-normalized, and verified that the normalized range has
	 * been entirely written to disk.
	 */
	new->bse_f_offset = offset;
	offset = normalize(offset, bl->bl_blocksize);
	if (offset < new->bse_f_offset) {
		if (is_range_written(be->be_inval, offset, new->bse_f_offset))
			new->bse_f_offset = offset;
		else
			new->bse_f_offset = offset + bl->bl_blocksize;
	}
	new_end = normalize_up(end, bl->bl_blocksize);
	if (end < new_end) {
		if (is_range_written(be->be_inval, end, new_end))
			end = new_end;
		else
			end = new_end - bl->bl_blocksize;
	}
	if (end <= new->bse_f_offset) {
		kfree(new);
		return 0;
	}
	new->bse_length = end - new->bse_f_offset;
	new->bse_devid = be->be_devid;
	new->bse_mdev = be->be_mdev;

	spin_lock(&bl->bl_ext_lock);
	add_to_commitlist(bl, new);
	spin_unlock(&bl->bl_ext_lock);
	return 0;
}

static void print_bl_extent(struct pnfs_block_extent *be)
{
	dprintk("PRINT EXTENT extent %p\n", be);
	if (be) {
		dprintk("        be_f_offset %llu\n", (u64)be->be_f_offset);
		dprintk("        be_length   %llu\n", (u64)be->be_length);
		dprintk("        be_v_offset %llu\n", (u64)be->be_v_offset);
		dprintk("        be_state    %d\n", be->be_state);
	}
}

static void
destroy_extent(struct kref *kref)
{
	struct pnfs_block_extent *be;

	be = container_of(kref, struct pnfs_block_extent, be_refcnt);
	dprintk("%s be=%p\n", __func__, be);
	kfree(be);
}

void
bl_put_extent(struct pnfs_block_extent *be)
{
	if (be) {
		dprintk("%s enter %p (%i)\n", __func__, be,
			atomic_read(&be->be_refcnt.refcount));
		kref_put(&be->be_refcnt, destroy_extent);
	}
}

struct pnfs_block_extent *bl_alloc_extent(void)
{
	struct pnfs_block_extent *be;

	be = kmalloc(sizeof(struct pnfs_block_extent), GFP_NOFS);
	if (!be)
		return NULL;
	INIT_LIST_HEAD(&be->be_node);
	kref_init(&be->be_refcnt);
	be->be_inval = NULL;
	return be;
}

static void print_elist(struct list_head *list)
{
	struct pnfs_block_extent *be;
	dprintk("****************\n");
	dprintk("Extent list looks like:\n");
	list_for_each_entry(be, list, be_node) {
		print_bl_extent(be);
	}
	dprintk("****************\n");
}

static inline int
extents_consistent(struct pnfs_block_extent *old, struct pnfs_block_extent *new)
{
	/* Note this assumes new->be_f_offset >= old->be_f_offset */
	return (new->be_state == old->be_state) &&
		((new->be_state == PNFS_BLOCK_NONE_DATA) ||
		 ((new->be_v_offset - old->be_v_offset ==
		   new->be_f_offset - old->be_f_offset) &&
		  new->be_mdev == old->be_mdev));
}

/* Adds new to appropriate list in bl, modifying new and removing existing
 * extents as appropriate to deal with overlaps.
 *
 * See bl_find_get_extent for list constraints.
 *
 * Refcount on new is already set.  If end up not using it, or error out,
 * need to put the reference.
 *
 * bl->bl_ext_lock is held by caller.
 */
int
bl_add_merge_extent(struct pnfs_block_layout *bl,
		     struct pnfs_block_extent *new)
{
	struct pnfs_block_extent *be, *tmp;
	sector_t end = new->be_f_offset + new->be_length;
	struct list_head *list;

	dprintk("%s enter with be=%p\n", __func__, new);
	print_bl_extent(new);
	list = &bl->bl_extents[bl_choose_list(new->be_state)];
	print_elist(list);

	/* Scan for proper place to insert, extending new to the left
	 * as much as possible.
	 */
	list_for_each_entry_safe_reverse(be, tmp, list, be_node) {
		if (new->be_f_offset >= be->be_f_offset + be->be_length)
			break;
		if (new->be_f_offset >= be->be_f_offset) {
			if (end <= be->be_f_offset + be->be_length) {
				/* new is a subset of existing be*/
				if (extents_consistent(be, new)) {
					dprintk("%s: new is subset, ignoring\n",
						__func__);
					bl_put_extent(new);
					return 0;
				} else {
					goto out_err;
				}
			} else {
				/* |<--   be   -->|
				 *          |<--   new   -->| */
				if (extents_consistent(be, new)) {
					/* extend new to fully replace be */
					new->be_length += new->be_f_offset -
						be->be_f_offset;
					new->be_f_offset = be->be_f_offset;
					new->be_v_offset = be->be_v_offset;
					dprintk("%s: removing %p\n", __func__, be);
					list_del(&be->be_node);
					bl_put_extent(be);
				} else {
					goto out_err;
				}
			}
		} else if (end >= be->be_f_offset + be->be_length) {
			/* new extent overlap existing be */
			if (extents_consistent(be, new)) {
				/* extend new to fully replace be */
				dprintk("%s: removing %p\n", __func__, be);
				list_del(&be->be_node);
				bl_put_extent(be);
			} else {
				goto out_err;
			}
		} else if (end > be->be_f_offset) {
			/*           |<--   be   -->|
			 *|<--   new   -->| */
			if (extents_consistent(new, be)) {
				/* extend new to fully replace be */
				new->be_length += be->be_f_offset + be->be_length -
					new->be_f_offset - new->be_length;
				dprintk("%s: removing %p\n", __func__, be);
				list_del(&be->be_node);
				bl_put_extent(be);
			} else {
				goto out_err;
			}
		}
	}
	/* Note that if we never hit the above break, be will not point to a
	 * valid extent.  However, in that case &be->be_node==list.
	 */
	list_add(&new->be_node, &be->be_node);
	dprintk("%s: inserting new\n", __func__);
	print_elist(list);
	/* FIXME - The per-list consistency checks have all been done,
	 * should now check cross-list consistency.
	 */
	return 0;

 out_err:
	bl_put_extent(new);
	return -EIO;
}

/* Returns extent, or NULL.  If a second READ extent exists, it is returned
 * in cow_read, if given.
 *
 * The extents are kept in two seperate ordered lists, one for READ and NONE,
 * one for READWRITE and INVALID.  Within each list, we assume:
 * 1. Extents are ordered by file offset.
 * 2. For any given isect, there is at most one extents that matches.
 */
struct pnfs_block_extent *
bl_find_get_extent(struct pnfs_block_layout *bl, sector_t isect,
	    struct pnfs_block_extent **cow_read)
{
	struct pnfs_block_extent *be, *cow, *ret;
	int i;

	dprintk("%s enter with isect %llu\n", __func__, (u64)isect);
	cow = ret = NULL;
	spin_lock(&bl->bl_ext_lock);
	for (i = 0; i < EXTENT_LISTS; i++) {
		list_for_each_entry_reverse(be, &bl->bl_extents[i], be_node) {
			if (isect >= be->be_f_offset + be->be_length)
				break;
			if (isect >= be->be_f_offset) {
				/* We have found an extent */
				dprintk("%s Get %p (%i)\n", __func__, be,
					atomic_read(&be->be_refcnt.refcount));
				kref_get(&be->be_refcnt);
				if (!ret)
					ret = be;
				else if (be->be_state != PNFS_BLOCK_READ_DATA)
					bl_put_extent(be);
				else
					cow = be;
				break;
			}
		}
		if (ret &&
		    (!cow_read || ret->be_state != PNFS_BLOCK_INVALID_DATA))
			break;
	}
	spin_unlock(&bl->bl_ext_lock);
	if (cow_read)
		*cow_read = cow;
	print_bl_extent(ret);
	return ret;
}

/* Similar to bl_find_get_extent, but called with lock held, and ignores cow */
static struct pnfs_block_extent *
bl_find_get_extent_locked(struct pnfs_block_layout *bl, sector_t isect)
{
	struct pnfs_block_extent *be, *ret = NULL;
	int i;

	dprintk("%s enter with isect %llu\n", __func__, (u64)isect);
	for (i = 0; i < EXTENT_LISTS; i++) {
		if (ret)
			break;
		list_for_each_entry_reverse(be, &bl->bl_extents[i], be_node) {
			if (isect >= be->be_f_offset + be->be_length)
				break;
			if (isect >= be->be_f_offset) {
				/* We have found an extent */
				dprintk("%s Get %p (%i)\n", __func__, be,
					atomic_read(&be->be_refcnt.refcount));
				kref_get(&be->be_refcnt);
				ret = be;
				break;
			}
		}
	}
	print_bl_extent(ret);
	return ret;
}

int
encode_pnfs_block_layoutupdate(struct pnfs_block_layout *bl,
			       struct xdr_stream *xdr,
			       const struct nfs4_layoutcommit_args *arg)
{
	struct pnfs_block_short_extent *lce, *save;
	unsigned int count = 0;
	__be32 *p, *xdr_start;

	dprintk("%s enter\n", __func__);
	/* BUG - creation of bl_commit is buggy - need to wait for
	 * entire block to be marked WRITTEN before it can be added.
	 */
	spin_lock(&bl->bl_ext_lock);
	/* Want to adjust for possible truncate */
	/* We now want to adjust argument range */

	/* XDR encode the ranges found */
	xdr_start = xdr_reserve_space(xdr, 8);
	if (!xdr_start)
		goto out;
	list_for_each_entry_safe(lce, save, &bl->bl_commit, bse_node) {
		p = xdr_reserve_space(xdr, 7 * 4 + sizeof(lce->bse_devid.data));
		if (!p)
			break;
		p = xdr_encode_opaque_fixed(p, lce->bse_devid.data, NFS4_DEVICEID4_SIZE);
		p = xdr_encode_hyper(p, lce->bse_f_offset << SECTOR_SHIFT);
		p = xdr_encode_hyper(p, lce->bse_length << SECTOR_SHIFT);
		p = xdr_encode_hyper(p, 0LL);
		*p++ = cpu_to_be32(PNFS_BLOCK_READWRITE_DATA);
		list_del(&lce->bse_node);
		list_add_tail(&lce->bse_node, &bl->bl_committing);
		bl->bl_count--;
		count++;
	}
	xdr_start[0] = cpu_to_be32((xdr->p - xdr_start - 1) * 4);
	xdr_start[1] = cpu_to_be32(count);
out:
	spin_unlock(&bl->bl_ext_lock);
	dprintk("%s found %i ranges\n", __func__, count);
	return 0;
}

/* Helper function to set_to_rw that initialize a new extent */
static void
_prep_new_extent(struct pnfs_block_extent *new,
		 struct pnfs_block_extent *orig,
		 sector_t offset, sector_t length, int state)
{
	kref_init(&new->be_refcnt);
	/* don't need to INIT_LIST_HEAD(&new->be_node) */
	memcpy(&new->be_devid, &orig->be_devid, sizeof(struct nfs4_deviceid));
	new->be_mdev = orig->be_mdev;
	new->be_f_offset = offset;
	new->be_length = length;
	new->be_v_offset = orig->be_v_offset - orig->be_f_offset + offset;
	new->be_state = state;
	new->be_inval = orig->be_inval;
}

/* Tries to merge be with extent in front of it in list.
 * Frees storage if not used.
 */
static struct pnfs_block_extent *
_front_merge(struct pnfs_block_extent *be, struct list_head *head,
	     struct pnfs_block_extent *storage)
{
	struct pnfs_block_extent *prev;

	if (!storage)
		goto no_merge;
	if (&be->be_node == head || be->be_node.prev == head)
		goto no_merge;
	prev = list_entry(be->be_node.prev, struct pnfs_block_extent, be_node);
	if ((prev->be_f_offset + prev->be_length != be->be_f_offset) ||
	    !extents_consistent(prev, be))
		goto no_merge;
	_prep_new_extent(storage, prev, prev->be_f_offset,
			 prev->be_length + be->be_length, prev->be_state);
	list_replace(&prev->be_node, &storage->be_node);
	bl_put_extent(prev);
	list_del(&be->be_node);
	bl_put_extent(be);
	return storage;

 no_merge:
	kfree(storage);
	return be;
}

static u64
set_to_rw(struct pnfs_block_layout *bl, u64 offset, u64 length)
{
	u64 rv = offset + length;
	struct pnfs_block_extent *be, *e1, *e2, *e3, *new, *old;
	struct pnfs_block_extent *children[3];
	struct pnfs_block_extent *merge1 = NULL, *merge2 = NULL;
	int i = 0, j;

	dprintk("%s(%llu, %llu)\n", __func__, offset, length);
	/* Create storage for up to three new extents e1, e2, e3 */
	e1 = kmalloc(sizeof(*e1), GFP_ATOMIC);
	e2 = kmalloc(sizeof(*e2), GFP_ATOMIC);
	e3 = kmalloc(sizeof(*e3), GFP_ATOMIC);
	/* BUG - we are ignoring any failure */
	if (!e1 || !e2 || !e3)
		goto out_nosplit;

	spin_lock(&bl->bl_ext_lock);
	be = bl_find_get_extent_locked(bl, offset);
	rv = be->be_f_offset + be->be_length;
	if (be->be_state != PNFS_BLOCK_INVALID_DATA) {
		spin_unlock(&bl->bl_ext_lock);
		goto out_nosplit;
	}
	/* Add e* to children, bumping e*'s krefs */
	if (be->be_f_offset != offset) {
		_prep_new_extent(e1, be, be->be_f_offset,
				 offset - be->be_f_offset,
				 PNFS_BLOCK_INVALID_DATA);
		children[i++] = e1;
		print_bl_extent(e1);
	} else
		merge1 = e1;
	_prep_new_extent(e2, be, offset,
			 min(length, be->be_f_offset + be->be_length - offset),
			 PNFS_BLOCK_READWRITE_DATA);
	children[i++] = e2;
	print_bl_extent(e2);
	if (offset + length < be->be_f_offset + be->be_length) {
		_prep_new_extent(e3, be, e2->be_f_offset + e2->be_length,
				 be->be_f_offset + be->be_length -
				 offset - length,
				 PNFS_BLOCK_INVALID_DATA);
		children[i++] = e3;
		print_bl_extent(e3);
	} else
		merge2 = e3;

	/* Remove be from list, and insert the e* */
	/* We don't get refs on e*, since this list is the base reference
	 * set when init'ed.
	 */
	if (i < 3)
		children[i] = NULL;
	new = children[0];
	list_replace(&be->be_node, &new->be_node);
	bl_put_extent(be);
	new = _front_merge(new, &bl->bl_extents[RW_EXTENT], merge1);
	for (j = 1; j < i; j++) {
		old = new;
		new = children[j];
		list_add(&new->be_node, &old->be_node);
	}
	if (merge2) {
		/* This is a HACK, should just create a _back_merge function */
		new = list_entry(new->be_node.next,
				 struct pnfs_block_extent, be_node);
		new = _front_merge(new, &bl->bl_extents[RW_EXTENT], merge2);
	}
	spin_unlock(&bl->bl_ext_lock);

	/* Since we removed the base reference above, be is now scheduled for
	 * destruction.
	 */
	bl_put_extent(be);
	dprintk("%s returns %llu after split\n", __func__, rv);
	return rv;

 out_nosplit:
	kfree(e1);
	kfree(e2);
	kfree(e3);
	dprintk("%s returns %llu without splitting\n", __func__, rv);
	return rv;
}

void
clean_pnfs_block_layoutupdate(struct pnfs_block_layout *bl,
			      const struct nfs4_layoutcommit_args *arg,
			      int status)
{
	struct pnfs_block_short_extent *lce, *save;

	dprintk("%s status %d\n", __func__, status);
	list_for_each_entry_safe(lce, save, &bl->bl_committing, bse_node) {
		if (likely(!status)) {
			u64 offset = lce->bse_f_offset;
			u64 end = offset + lce->bse_length;

			do {
				offset = set_to_rw(bl, offset, end - offset);
			} while (offset < end);
			list_del(&lce->bse_node);

			kfree(lce);
		} else {
			list_del(&lce->bse_node);
			spin_lock(&bl->bl_ext_lock);
			add_to_commitlist(bl, lce);
			spin_unlock(&bl->bl_ext_lock);
		}
	}
}

int bl_push_one_short_extent(struct pnfs_inval_markings *marks)
{
	struct pnfs_block_short_extent *new;

	new = kmalloc(sizeof(*new), GFP_NOFS);
	if (unlikely(!new))
		return -ENOMEM;

	spin_lock_bh(&marks->im_lock);
	list_add(&new->bse_node, &marks->im_extents);
	spin_unlock_bh(&marks->im_lock);

	return 0;
}

struct pnfs_block_short_extent *
bl_pop_one_short_extent(struct pnfs_inval_markings *marks)
{
	struct pnfs_block_short_extent *rv = NULL;

	spin_lock_bh(&marks->im_lock);
	if (!list_empty(&marks->im_extents)) {
		rv = list_entry((&marks->im_extents)->next,
				struct pnfs_block_short_extent, bse_node);
		list_del_init(&rv->bse_node);
	}
	spin_unlock_bh(&marks->im_lock);

	return rv;
}

void bl_free_short_extents(struct pnfs_inval_markings *marks, int num_to_free)
{
	struct pnfs_block_short_extent *se = NULL, *tmp;

	if (num_to_free <= 0)
		return;

	spin_lock(&marks->im_lock);
	list_for_each_entry_safe(se, tmp, &marks->im_extents, bse_node) {
		list_del(&se->bse_node);
		kfree(se);
		if (--num_to_free == 0)
			break;
	}
	spin_unlock(&marks->im_lock);

	BUG_ON(num_to_free > 0);
}