summaryrefslogtreecommitdiff
path: root/drivers/target/target_core_iblock.c
blob: 4069a1edcfa34d8e25162e5062d8e311c743046c (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*******************************************************************************
 * Filename:  target_core_iblock.c
 *
 * This file contains the Storage Engine  <-> Linux BlockIO transport
 * specific functions.
 *
 * (c) Copyright 2003-2013 Datera, Inc.
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 ******************************************************************************/

#include <linux/string.h>
#include <linux/parser.h>
#include <linux/timer.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/bio.h>
#include <linux/genhd.h>
#include <linux/file.h>
#include <linux/module.h>
#include <scsi/scsi_proto.h>
#include <asm/unaligned.h>

#include <target/target_core_base.h>
#include <target/target_core_backend.h>

#include "target_core_iblock.h"

#define IBLOCK_MAX_BIO_PER_TASK	 32	/* max # of bios to submit at a time */
#define IBLOCK_BIO_POOL_SIZE	128

static inline struct iblock_dev *IBLOCK_DEV(struct se_device *dev)
{
	return container_of(dev, struct iblock_dev, dev);
}


static int iblock_attach_hba(struct se_hba *hba, u32 host_id)
{
	pr_debug("CORE_HBA[%d] - TCM iBlock HBA Driver %s on"
		" Generic Target Core Stack %s\n", hba->hba_id,
		IBLOCK_VERSION, TARGET_CORE_VERSION);
	return 0;
}

static void iblock_detach_hba(struct se_hba *hba)
{
}

static struct se_device *iblock_alloc_device(struct se_hba *hba, const char *name)
{
	struct iblock_dev *ib_dev = NULL;

	ib_dev = kzalloc(sizeof(struct iblock_dev), GFP_KERNEL);
	if (!ib_dev) {
		pr_err("Unable to allocate struct iblock_dev\n");
		return NULL;
	}

	ib_dev->ibd_plug = kcalloc(nr_cpu_ids, sizeof(*ib_dev->ibd_plug),
				   GFP_KERNEL);
	if (!ib_dev->ibd_plug)
		goto free_dev;

	pr_debug( "IBLOCK: Allocated ib_dev for %s\n", name);

	return &ib_dev->dev;

free_dev:
	kfree(ib_dev);
	return NULL;
}

static int iblock_configure_device(struct se_device *dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	struct request_queue *q;
	struct block_device *bd = NULL;
	struct blk_integrity *bi;
	fmode_t mode;
	unsigned int max_write_zeroes_sectors;
	int ret;

	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
		pr_err("Missing udev_path= parameters for IBLOCK\n");
		return -EINVAL;
	}

	ret = bioset_init(&ib_dev->ibd_bio_set, IBLOCK_BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
	if (ret) {
		pr_err("IBLOCK: Unable to create bioset\n");
		goto out;
	}

	pr_debug( "IBLOCK: Claiming struct block_device: %s\n",
			ib_dev->ibd_udev_path);

	mode = FMODE_READ|FMODE_EXCL;
	if (!ib_dev->ibd_readonly)
		mode |= FMODE_WRITE;
	else
		dev->dev_flags |= DF_READ_ONLY;

	bd = blkdev_get_by_path(ib_dev->ibd_udev_path, mode, ib_dev);
	if (IS_ERR(bd)) {
		ret = PTR_ERR(bd);
		goto out_free_bioset;
	}
	ib_dev->ibd_bd = bd;

	q = bdev_get_queue(bd);

	dev->dev_attrib.hw_block_size = bdev_logical_block_size(bd);
	dev->dev_attrib.hw_max_sectors = queue_max_hw_sectors(q);
	dev->dev_attrib.hw_queue_depth = q->nr_requests;

	if (target_configure_unmap_from_queue(&dev->dev_attrib, q))
		pr_debug("IBLOCK: BLOCK Discard support available,"
			 " disabled by default\n");

	/*
	 * Enable write same emulation for IBLOCK and use 0xFFFF as
	 * the smaller WRITE_SAME(10) only has a two-byte block count.
	 */
	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
	if (max_write_zeroes_sectors)
		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
	else
		dev->dev_attrib.max_write_same_len = 0xFFFF;

	if (blk_queue_nonrot(q))
		dev->dev_attrib.is_nonrot = 1;

	bi = bdev_get_integrity(bd);
	if (bi) {
		struct bio_set *bs = &ib_dev->ibd_bio_set;

		if (!strcmp(bi->profile->name, "T10-DIF-TYPE3-IP") ||
		    !strcmp(bi->profile->name, "T10-DIF-TYPE1-IP")) {
			pr_err("IBLOCK export of blk_integrity: %s not"
			       " supported\n", bi->profile->name);
			ret = -ENOSYS;
			goto out_blkdev_put;
		}

		if (!strcmp(bi->profile->name, "T10-DIF-TYPE3-CRC")) {
			dev->dev_attrib.pi_prot_type = TARGET_DIF_TYPE3_PROT;
		} else if (!strcmp(bi->profile->name, "T10-DIF-TYPE1-CRC")) {
			dev->dev_attrib.pi_prot_type = TARGET_DIF_TYPE1_PROT;
		}

		if (dev->dev_attrib.pi_prot_type) {
			if (bioset_integrity_create(bs, IBLOCK_BIO_POOL_SIZE) < 0) {
				pr_err("Unable to allocate bioset for PI\n");
				ret = -ENOMEM;
				goto out_blkdev_put;
			}
			pr_debug("IBLOCK setup BIP bs->bio_integrity_pool: %p\n",
				 &bs->bio_integrity_pool);
		}
		dev->dev_attrib.hw_pi_prot_type = dev->dev_attrib.pi_prot_type;
	}

	return 0;

out_blkdev_put:
	blkdev_put(ib_dev->ibd_bd, FMODE_WRITE|FMODE_READ|FMODE_EXCL);
out_free_bioset:
	bioset_exit(&ib_dev->ibd_bio_set);
out:
	return ret;
}

static void iblock_dev_call_rcu(struct rcu_head *p)
{
	struct se_device *dev = container_of(p, struct se_device, rcu_head);
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);

	kfree(ib_dev->ibd_plug);
	kfree(ib_dev);
}

static void iblock_free_device(struct se_device *dev)
{
	call_rcu(&dev->rcu_head, iblock_dev_call_rcu);
}

static void iblock_destroy_device(struct se_device *dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);

	if (ib_dev->ibd_bd != NULL)
		blkdev_put(ib_dev->ibd_bd, FMODE_WRITE|FMODE_READ|FMODE_EXCL);
	bioset_exit(&ib_dev->ibd_bio_set);
}

static struct se_dev_plug *iblock_plug_device(struct se_device *se_dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(se_dev);
	struct iblock_dev_plug *ib_dev_plug;

	/*
	 * Each se_device has a per cpu work this can be run from. We
	 * shouldn't have multiple threads on the same cpu calling this
	 * at the same time.
	 */
	ib_dev_plug = &ib_dev->ibd_plug[raw_smp_processor_id()];
	if (test_and_set_bit(IBD_PLUGF_PLUGGED, &ib_dev_plug->flags))
		return NULL;

	blk_start_plug(&ib_dev_plug->blk_plug);
	return &ib_dev_plug->se_plug;
}

static void iblock_unplug_device(struct se_dev_plug *se_plug)
{
	struct iblock_dev_plug *ib_dev_plug = container_of(se_plug,
					struct iblock_dev_plug, se_plug);

	blk_finish_plug(&ib_dev_plug->blk_plug);
	clear_bit(IBD_PLUGF_PLUGGED, &ib_dev_plug->flags);
}

static unsigned long long iblock_emulate_read_cap_with_block_size(
	struct se_device *dev,
	struct block_device *bd,
	struct request_queue *q)
{
	unsigned long long blocks_long = (div_u64(i_size_read(bd->bd_inode),
					bdev_logical_block_size(bd)) - 1);
	u32 block_size = bdev_logical_block_size(bd);

	if (block_size == dev->dev_attrib.block_size)
		return blocks_long;

	switch (block_size) {
	case 4096:
		switch (dev->dev_attrib.block_size) {
		case 2048:
			blocks_long <<= 1;
			break;
		case 1024:
			blocks_long <<= 2;
			break;
		case 512:
			blocks_long <<= 3;
			break;
		default:
			break;
		}
		break;
	case 2048:
		switch (dev->dev_attrib.block_size) {
		case 4096:
			blocks_long >>= 1;
			break;
		case 1024:
			blocks_long <<= 1;
			break;
		case 512:
			blocks_long <<= 2;
			break;
		default:
			break;
		}
		break;
	case 1024:
		switch (dev->dev_attrib.block_size) {
		case 4096:
			blocks_long >>= 2;
			break;
		case 2048:
			blocks_long >>= 1;
			break;
		case 512:
			blocks_long <<= 1;
			break;
		default:
			break;
		}
		break;
	case 512:
		switch (dev->dev_attrib.block_size) {
		case 4096:
			blocks_long >>= 3;
			break;
		case 2048:
			blocks_long >>= 2;
			break;
		case 1024:
			blocks_long >>= 1;
			break;
		default:
			break;
		}
		break;
	default:
		break;
	}

	return blocks_long;
}

static void iblock_complete_cmd(struct se_cmd *cmd)
{
	struct iblock_req *ibr = cmd->priv;
	u8 status;

	if (!refcount_dec_and_test(&ibr->pending))
		return;

	if (atomic_read(&ibr->ib_bio_err_cnt))
		status = SAM_STAT_CHECK_CONDITION;
	else
		status = SAM_STAT_GOOD;

	target_complete_cmd(cmd, status);
	kfree(ibr);
}

static void iblock_bio_done(struct bio *bio)
{
	struct se_cmd *cmd = bio->bi_private;
	struct iblock_req *ibr = cmd->priv;

	if (bio->bi_status) {
		pr_err("bio error: %p,  err: %d\n", bio, bio->bi_status);
		/*
		 * Bump the ib_bio_err_cnt and release bio.
		 */
		atomic_inc(&ibr->ib_bio_err_cnt);
		smp_mb__after_atomic();
	}

	bio_put(bio);

	iblock_complete_cmd(cmd);
}

static struct bio *iblock_get_bio(struct se_cmd *cmd, sector_t lba, u32 sg_num,
				  unsigned int opf)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(cmd->se_dev);
	struct bio *bio;

	/*
	 * Only allocate as many vector entries as the bio code allows us to,
	 * we'll loop later on until we have handled the whole request.
	 */
	bio = bio_alloc_bioset(GFP_NOIO, bio_max_segs(sg_num),
				&ib_dev->ibd_bio_set);
	if (!bio) {
		pr_err("Unable to allocate memory for bio\n");
		return NULL;
	}

	bio_set_dev(bio, ib_dev->ibd_bd);
	bio->bi_private = cmd;
	bio->bi_end_io = &iblock_bio_done;
	bio->bi_iter.bi_sector = lba;
	bio->bi_opf = opf;

	return bio;
}

static void iblock_submit_bios(struct bio_list *list)
{
	struct blk_plug plug;
	struct bio *bio;
	/*
	 * The block layer handles nested plugs, so just plug/unplug to handle
	 * fabric drivers that didn't support batching and multi bio cmds.
	 */
	blk_start_plug(&plug);
	while ((bio = bio_list_pop(list)))
		submit_bio(bio);
	blk_finish_plug(&plug);
}

static void iblock_end_io_flush(struct bio *bio)
{
	struct se_cmd *cmd = bio->bi_private;

	if (bio->bi_status)
		pr_err("IBLOCK: cache flush failed: %d\n", bio->bi_status);

	if (cmd) {
		if (bio->bi_status)
			target_complete_cmd(cmd, SAM_STAT_CHECK_CONDITION);
		else
			target_complete_cmd(cmd, SAM_STAT_GOOD);
	}

	bio_put(bio);
}

/*
 * Implement SYCHRONIZE CACHE.  Note that we can't handle lba ranges and must
 * always flush the whole cache.
 */
static sense_reason_t
iblock_execute_sync_cache(struct se_cmd *cmd)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(cmd->se_dev);
	int immed = (cmd->t_task_cdb[1] & 0x2);
	struct bio *bio;

	/*
	 * If the Immediate bit is set, queue up the GOOD response
	 * for this SYNCHRONIZE_CACHE op.
	 */
	if (immed)
		target_complete_cmd(cmd, SAM_STAT_GOOD);

	bio = bio_alloc(GFP_KERNEL, 0);
	bio->bi_end_io = iblock_end_io_flush;
	bio_set_dev(bio, ib_dev->ibd_bd);
	bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
	if (!immed)
		bio->bi_private = cmd;
	submit_bio(bio);
	return 0;
}

static sense_reason_t
iblock_execute_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb)
{
	struct block_device *bdev = IBLOCK_DEV(cmd->se_dev)->ibd_bd;
	struct se_device *dev = cmd->se_dev;
	int ret;

	ret = blkdev_issue_discard(bdev,
				   target_to_linux_sector(dev, lba),
				   target_to_linux_sector(dev,  nolb),
				   GFP_KERNEL, 0);
	if (ret < 0) {
		pr_err("blkdev_issue_discard() failed: %d\n", ret);
		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
	}

	return 0;
}

static sense_reason_t
iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
{
	struct se_device *dev = cmd->se_dev;
	struct scatterlist *sg = &cmd->t_data_sg[0];
	unsigned char *buf, *not_zero;
	int ret;

	buf = kmap(sg_page(sg)) + sg->offset;
	if (!buf)
		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
	/*
	 * Fall back to block_execute_write_same() slow-path if
	 * incoming WRITE_SAME payload does not contain zeros.
	 */
	not_zero = memchr_inv(buf, 0x00, cmd->data_length);
	kunmap(sg_page(sg));

	if (not_zero)
		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

	ret = blkdev_issue_zeroout(bdev,
				target_to_linux_sector(dev, cmd->t_task_lba),
				target_to_linux_sector(dev,
					sbc_get_write_same_sectors(cmd)),
				GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
	if (ret)
		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

	target_complete_cmd(cmd, SAM_STAT_GOOD);
	return 0;
}

static sense_reason_t
iblock_execute_write_same(struct se_cmd *cmd)
{
	struct block_device *bdev = IBLOCK_DEV(cmd->se_dev)->ibd_bd;
	struct iblock_req *ibr;
	struct scatterlist *sg;
	struct bio *bio;
	struct bio_list list;
	struct se_device *dev = cmd->se_dev;
	sector_t block_lba = target_to_linux_sector(dev, cmd->t_task_lba);
	sector_t sectors = target_to_linux_sector(dev,
					sbc_get_write_same_sectors(cmd));

	if (cmd->prot_op) {
		pr_err("WRITE_SAME: Protection information with IBLOCK"
		       " backends not supported\n");
		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
	}
	sg = &cmd->t_data_sg[0];

	if (cmd->t_data_nents > 1 ||
	    sg->length != cmd->se_dev->dev_attrib.block_size) {
		pr_err("WRITE_SAME: Illegal SGL t_data_nents: %u length: %u"
			" block_size: %u\n", cmd->t_data_nents, sg->length,
			cmd->se_dev->dev_attrib.block_size);
		return TCM_INVALID_CDB_FIELD;
	}

	if (bdev_write_zeroes_sectors(bdev)) {
		if (!iblock_execute_zero_out(bdev, cmd))
			return 0;
	}

	ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
	if (!ibr)
		goto fail;
	cmd->priv = ibr;

	bio = iblock_get_bio(cmd, block_lba, 1, REQ_OP_WRITE);
	if (!bio)
		goto fail_free_ibr;

	bio_list_init(&list);
	bio_list_add(&list, bio);

	refcount_set(&ibr->pending, 1);

	while (sectors) {
		while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
				!= sg->length) {

			bio = iblock_get_bio(cmd, block_lba, 1, REQ_OP_WRITE);
			if (!bio)
				goto fail_put_bios;

			refcount_inc(&ibr->pending);
			bio_list_add(&list, bio);
		}

		/* Always in 512 byte units for Linux/Block */
		block_lba += sg->length >> SECTOR_SHIFT;
		sectors -= sg->length >> SECTOR_SHIFT;
	}

	iblock_submit_bios(&list);
	return 0;

fail_put_bios:
	while ((bio = bio_list_pop(&list)))
		bio_put(bio);
fail_free_ibr:
	kfree(ibr);
fail:
	return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}

enum {
	Opt_udev_path, Opt_readonly, Opt_force, Opt_err
};

static match_table_t tokens = {
	{Opt_udev_path, "udev_path=%s"},
	{Opt_readonly, "readonly=%d"},
	{Opt_force, "force=%d"},
	{Opt_err, NULL}
};

static ssize_t iblock_set_configfs_dev_params(struct se_device *dev,
		const char *page, ssize_t count)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	char *orig, *ptr, *arg_p, *opts;
	substring_t args[MAX_OPT_ARGS];
	int ret = 0, token;
	unsigned long tmp_readonly;

	opts = kstrdup(page, GFP_KERNEL);
	if (!opts)
		return -ENOMEM;

	orig = opts;

	while ((ptr = strsep(&opts, ",\n")) != NULL) {
		if (!*ptr)
			continue;

		token = match_token(ptr, tokens, args);
		switch (token) {
		case Opt_udev_path:
			if (ib_dev->ibd_bd) {
				pr_err("Unable to set udev_path= while"
					" ib_dev->ibd_bd exists\n");
				ret = -EEXIST;
				goto out;
			}
			if (match_strlcpy(ib_dev->ibd_udev_path, &args[0],
				SE_UDEV_PATH_LEN) == 0) {
				ret = -EINVAL;
				break;
			}
			pr_debug("IBLOCK: Referencing UDEV path: %s\n",
					ib_dev->ibd_udev_path);
			ib_dev->ibd_flags |= IBDF_HAS_UDEV_PATH;
			break;
		case Opt_readonly:
			arg_p = match_strdup(&args[0]);
			if (!arg_p) {
				ret = -ENOMEM;
				break;
			}
			ret = kstrtoul(arg_p, 0, &tmp_readonly);
			kfree(arg_p);
			if (ret < 0) {
				pr_err("kstrtoul() failed for"
						" readonly=\n");
				goto out;
			}
			ib_dev->ibd_readonly = tmp_readonly;
			pr_debug("IBLOCK: readonly: %d\n", ib_dev->ibd_readonly);
			break;
		case Opt_force:
			break;
		default:
			break;
		}
	}

out:
	kfree(orig);
	return (!ret) ? count : ret;
}

static ssize_t iblock_show_configfs_dev_params(struct se_device *dev, char *b)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	struct block_device *bd = ib_dev->ibd_bd;
	char buf[BDEVNAME_SIZE];
	ssize_t bl = 0;

	if (bd)
		bl += sprintf(b + bl, "iBlock device: %s",
				bdevname(bd, buf));
	if (ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)
		bl += sprintf(b + bl, "  UDEV PATH: %s",
				ib_dev->ibd_udev_path);
	bl += sprintf(b + bl, "  readonly: %d\n", ib_dev->ibd_readonly);

	bl += sprintf(b + bl, "        ");
	if (bd) {
		bl += sprintf(b + bl, "Major: %d Minor: %d  %s\n",
			MAJOR(bd->bd_dev), MINOR(bd->bd_dev),
			"CLAIMED: IBLOCK");
	} else {
		bl += sprintf(b + bl, "Major: 0 Minor: 0\n");
	}

	return bl;
}

static int
iblock_alloc_bip(struct se_cmd *cmd, struct bio *bio,
		 struct sg_mapping_iter *miter)
{
	struct se_device *dev = cmd->se_dev;
	struct blk_integrity *bi;
	struct bio_integrity_payload *bip;
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	int rc;
	size_t resid, len;

	bi = bdev_get_integrity(ib_dev->ibd_bd);
	if (!bi) {
		pr_err("Unable to locate bio_integrity\n");
		return -ENODEV;
	}

	bip = bio_integrity_alloc(bio, GFP_NOIO, bio_max_segs(cmd->t_prot_nents));
	if (IS_ERR(bip)) {
		pr_err("Unable to allocate bio_integrity_payload\n");
		return PTR_ERR(bip);
	}

	bip->bip_iter.bi_size = bio_integrity_bytes(bi, bio_sectors(bio));
	/* virtual start sector must be in integrity interval units */
	bip_set_seed(bip, bio->bi_iter.bi_sector >>
				  (bi->interval_exp - SECTOR_SHIFT));

	pr_debug("IBLOCK BIP Size: %u Sector: %llu\n", bip->bip_iter.bi_size,
		 (unsigned long long)bip->bip_iter.bi_sector);

	resid = bip->bip_iter.bi_size;
	while (resid > 0 && sg_miter_next(miter)) {

		len = min_t(size_t, miter->length, resid);
		rc = bio_integrity_add_page(bio, miter->page, len,
					    offset_in_page(miter->addr));
		if (rc != len) {
			pr_err("bio_integrity_add_page() failed; %d\n", rc);
			sg_miter_stop(miter);
			return -ENOMEM;
		}

		pr_debug("Added bio integrity page: %p length: %zu offset: %lu\n",
			  miter->page, len, offset_in_page(miter->addr));

		resid -= len;
		if (len < miter->length)
			miter->consumed -= miter->length - len;
	}
	sg_miter_stop(miter);

	return 0;
}

static sense_reason_t
iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
		  enum dma_data_direction data_direction)
{
	struct se_device *dev = cmd->se_dev;
	sector_t block_lba = target_to_linux_sector(dev, cmd->t_task_lba);
	struct iblock_req *ibr;
	struct bio *bio;
	struct bio_list list;
	struct scatterlist *sg;
	u32 sg_num = sgl_nents;
	unsigned int opf;
	unsigned bio_cnt;
	int i, rc;
	struct sg_mapping_iter prot_miter;
	unsigned int miter_dir;

	if (data_direction == DMA_TO_DEVICE) {
		struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
		struct request_queue *q = bdev_get_queue(ib_dev->ibd_bd);
		/*
		 * Force writethrough using REQ_FUA if a volatile write cache
		 * is not enabled, or if initiator set the Force Unit Access bit.
		 */
		opf = REQ_OP_WRITE;
		miter_dir = SG_MITER_TO_SG;
		if (test_bit(QUEUE_FLAG_FUA, &q->queue_flags)) {
			if (cmd->se_cmd_flags & SCF_FUA)
				opf |= REQ_FUA;
			else if (!test_bit(QUEUE_FLAG_WC, &q->queue_flags))
				opf |= REQ_FUA;
		}
	} else {
		opf = REQ_OP_READ;
		miter_dir = SG_MITER_FROM_SG;
	}

	ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
	if (!ibr)
		goto fail;
	cmd->priv = ibr;

	if (!sgl_nents) {
		refcount_set(&ibr->pending, 1);
		iblock_complete_cmd(cmd);
		return 0;
	}

	bio = iblock_get_bio(cmd, block_lba, sgl_nents, opf);
	if (!bio)
		goto fail_free_ibr;

	bio_list_init(&list);
	bio_list_add(&list, bio);

	refcount_set(&ibr->pending, 2);
	bio_cnt = 1;

	if (cmd->prot_type && dev->dev_attrib.pi_prot_type)
		sg_miter_start(&prot_miter, cmd->t_prot_sg, cmd->t_prot_nents,
			       miter_dir);

	for_each_sg(sgl, sg, sgl_nents, i) {
		/*
		 * XXX: if the length the device accepts is shorter than the
		 *	length of the S/G list entry this will cause and
		 *	endless loop.  Better hope no driver uses huge pages.
		 */
		while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
				!= sg->length) {
			if (cmd->prot_type && dev->dev_attrib.pi_prot_type) {
				rc = iblock_alloc_bip(cmd, bio, &prot_miter);
				if (rc)
					goto fail_put_bios;
			}

			if (bio_cnt >= IBLOCK_MAX_BIO_PER_TASK) {
				iblock_submit_bios(&list);
				bio_cnt = 0;
			}

			bio = iblock_get_bio(cmd, block_lba, sg_num, opf);
			if (!bio)
				goto fail_put_bios;

			refcount_inc(&ibr->pending);
			bio_list_add(&list, bio);
			bio_cnt++;
		}

		/* Always in 512 byte units for Linux/Block */
		block_lba += sg->length >> SECTOR_SHIFT;
		sg_num--;
	}

	if (cmd->prot_type && dev->dev_attrib.pi_prot_type) {
		rc = iblock_alloc_bip(cmd, bio, &prot_miter);
		if (rc)
			goto fail_put_bios;
	}

	iblock_submit_bios(&list);
	iblock_complete_cmd(cmd);
	return 0;

fail_put_bios:
	while ((bio = bio_list_pop(&list)))
		bio_put(bio);
fail_free_ibr:
	kfree(ibr);
fail:
	return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}

static sector_t iblock_get_blocks(struct se_device *dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	struct block_device *bd = ib_dev->ibd_bd;
	struct request_queue *q = bdev_get_queue(bd);

	return iblock_emulate_read_cap_with_block_size(dev, bd, q);
}

static sector_t iblock_get_alignment_offset_lbas(struct se_device *dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	struct block_device *bd = ib_dev->ibd_bd;
	int ret;

	ret = bdev_alignment_offset(bd);
	if (ret == -1)
		return 0;

	/* convert offset-bytes to offset-lbas */
	return ret / bdev_logical_block_size(bd);
}

static unsigned int iblock_get_lbppbe(struct se_device *dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	struct block_device *bd = ib_dev->ibd_bd;
	unsigned int logs_per_phys =
		bdev_physical_block_size(bd) / bdev_logical_block_size(bd);

	return ilog2(logs_per_phys);
}

static unsigned int iblock_get_io_min(struct se_device *dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	struct block_device *bd = ib_dev->ibd_bd;

	return bdev_io_min(bd);
}

static unsigned int iblock_get_io_opt(struct se_device *dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	struct block_device *bd = ib_dev->ibd_bd;

	return bdev_io_opt(bd);
}

static struct sbc_ops iblock_sbc_ops = {
	.execute_rw		= iblock_execute_rw,
	.execute_sync_cache	= iblock_execute_sync_cache,
	.execute_write_same	= iblock_execute_write_same,
	.execute_unmap		= iblock_execute_unmap,
};

static sense_reason_t
iblock_parse_cdb(struct se_cmd *cmd)
{
	return sbc_parse_cdb(cmd, &iblock_sbc_ops);
}

static bool iblock_get_write_cache(struct se_device *dev)
{
	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
	struct block_device *bd = ib_dev->ibd_bd;
	struct request_queue *q = bdev_get_queue(bd);

	return test_bit(QUEUE_FLAG_WC, &q->queue_flags);
}

static const struct target_backend_ops iblock_ops = {
	.name			= "iblock",
	.inquiry_prod		= "IBLOCK",
	.inquiry_rev		= IBLOCK_VERSION,
	.owner			= THIS_MODULE,
	.attach_hba		= iblock_attach_hba,
	.detach_hba		= iblock_detach_hba,
	.alloc_device		= iblock_alloc_device,
	.configure_device	= iblock_configure_device,
	.destroy_device		= iblock_destroy_device,
	.free_device		= iblock_free_device,
	.plug_device		= iblock_plug_device,
	.unplug_device		= iblock_unplug_device,
	.parse_cdb		= iblock_parse_cdb,
	.set_configfs_dev_params = iblock_set_configfs_dev_params,
	.show_configfs_dev_params = iblock_show_configfs_dev_params,
	.get_device_type	= sbc_get_device_type,
	.get_blocks		= iblock_get_blocks,
	.get_alignment_offset_lbas = iblock_get_alignment_offset_lbas,
	.get_lbppbe		= iblock_get_lbppbe,
	.get_io_min		= iblock_get_io_min,
	.get_io_opt		= iblock_get_io_opt,
	.get_write_cache	= iblock_get_write_cache,
	.tb_dev_attrib_attrs	= sbc_attrib_attrs,
};

static int __init iblock_module_init(void)
{
	return transport_backend_register(&iblock_ops);
}

static void __exit iblock_module_exit(void)
{
	target_backend_unregister(&iblock_ops);
}

MODULE_DESCRIPTION("TCM IBLOCK subsystem plugin");
MODULE_AUTHOR("nab@Linux-iSCSI.org");
MODULE_LICENSE("GPL");

module_init(iblock_module_init);
module_exit(iblock_module_exit);