summaryrefslogtreecommitdiff
path: root/include/linux/bio.h
blob: f87abaa898f0035f21613dc66e12594d04201f0b (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
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
 */
#ifndef __LINUX_BIO_H
#define __LINUX_BIO_H

#include <linux/highmem.h>
#include <linux/mempool.h>
#include <linux/ioprio.h>

#ifdef CONFIG_BLOCK
/* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
#include <linux/blk_types.h>

#define BIO_DEBUG

#ifdef BIO_DEBUG
#define BIO_BUG_ON	BUG_ON
#else
#define BIO_BUG_ON
#endif

#define BIO_MAX_PAGES		256

#define bio_prio(bio)			(bio)->bi_ioprio
#define bio_set_prio(bio, prio)		((bio)->bi_ioprio = prio)

#define bio_iter_iovec(bio, iter)				\
	bvec_iter_bvec((bio)->bi_io_vec, (iter))

#define bio_iter_page(bio, iter)				\
	bvec_iter_page((bio)->bi_io_vec, (iter))
#define bio_iter_len(bio, iter)					\
	bvec_iter_len((bio)->bi_io_vec, (iter))
#define bio_iter_offset(bio, iter)				\
	bvec_iter_offset((bio)->bi_io_vec, (iter))

#define bio_page(bio)		bio_iter_page((bio), (bio)->bi_iter)
#define bio_offset(bio)		bio_iter_offset((bio), (bio)->bi_iter)
#define bio_iovec(bio)		bio_iter_iovec((bio), (bio)->bi_iter)

#define bio_multiple_segments(bio)				\
	((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)

#define bvec_iter_sectors(iter)	((iter).bi_size >> 9)
#define bvec_iter_end_sector(iter) ((iter).bi_sector + bvec_iter_sectors((iter)))

#define bio_sectors(bio)	bvec_iter_sectors((bio)->bi_iter)
#define bio_end_sector(bio)	bvec_iter_end_sector((bio)->bi_iter)

/*
 * Return the data direction, READ or WRITE.
 */
#define bio_data_dir(bio) \
	(op_is_write(bio_op(bio)) ? WRITE : READ)

/*
 * Check whether this bio carries any data or not. A NULL bio is allowed.
 */
static inline bool bio_has_data(struct bio *bio)
{
	if (bio &&
	    bio->bi_iter.bi_size &&
	    bio_op(bio) != REQ_OP_DISCARD &&
	    bio_op(bio) != REQ_OP_SECURE_ERASE &&
	    bio_op(bio) != REQ_OP_WRITE_ZEROES)
		return true;

	return false;
}

static inline bool bio_no_advance_iter(struct bio *bio)
{
	return bio_op(bio) == REQ_OP_DISCARD ||
	       bio_op(bio) == REQ_OP_SECURE_ERASE ||
	       bio_op(bio) == REQ_OP_WRITE_SAME ||
	       bio_op(bio) == REQ_OP_WRITE_ZEROES;
}

static inline bool bio_mergeable(struct bio *bio)
{
	if (bio->bi_opf & REQ_NOMERGE_FLAGS)
		return false;

	return true;
}

static inline unsigned int bio_cur_bytes(struct bio *bio)
{
	if (bio_has_data(bio))
		return bio_iovec(bio).bv_len;
	else /* dataless requests such as discard */
		return bio->bi_iter.bi_size;
}

static inline void *bio_data(struct bio *bio)
{
	if (bio_has_data(bio))
		return page_address(bio_page(bio)) + bio_offset(bio);

	return NULL;
}

static inline bool bio_full(struct bio *bio)
{
	return bio->bi_vcnt >= bio->bi_max_vecs;
}

static inline bool bio_next_segment(const struct bio *bio,
				    struct bvec_iter_all *iter)
{
	if (iter->idx >= bio->bi_vcnt)
		return false;

	bvec_advance(&bio->bi_io_vec[iter->idx], iter);
	return true;
}

/*
 * drivers should _never_ use the all version - the bio may have been split
 * before it got to the driver and the driver won't own all of it
 */
#define bio_for_each_segment_all(bvl, bio, iter) \
	for (bvl = bvec_init_iter_all(&iter); bio_next_segment((bio), &iter); )

static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
				    unsigned bytes)
{
	iter->bi_sector += bytes >> 9;

	if (bio_no_advance_iter(bio))
		iter->bi_size -= bytes;
	else
		bvec_iter_advance(bio->bi_io_vec, iter, bytes);
		/* TODO: It is reasonable to complete bio with error here. */
}

#define __bio_for_each_segment(bvl, bio, iter, start)			\
	for (iter = (start);						\
	     (iter).bi_size &&						\
		((bvl = bio_iter_iovec((bio), (iter))), 1);		\
	     bio_advance_iter((bio), &(iter), (bvl).bv_len))

#define bio_for_each_segment(bvl, bio, iter)				\
	__bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)

#define __bio_for_each_bvec(bvl, bio, iter, start)		\
	for (iter = (start);						\
	     (iter).bi_size &&						\
		((bvl = mp_bvec_iter_bvec((bio)->bi_io_vec, (iter))), 1); \
	     bio_advance_iter((bio), &(iter), (bvl).bv_len))

/* iterate over multi-page bvec */
#define bio_for_each_bvec(bvl, bio, iter)			\
	__bio_for_each_bvec(bvl, bio, iter, (bio)->bi_iter)

#define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)

static inline unsigned bio_segments(struct bio *bio)
{
	unsigned segs = 0;
	struct bio_vec bv;
	struct bvec_iter iter;

	/*
	 * We special case discard/write same/write zeroes, because they
	 * interpret bi_size differently:
	 */

	switch (bio_op(bio)) {
	case REQ_OP_DISCARD:
	case REQ_OP_SECURE_ERASE:
	case REQ_OP_WRITE_ZEROES:
		return 0;
	case REQ_OP_WRITE_SAME:
		return 1;
	default:
		break;
	}

	bio_for_each_segment(bv, bio, iter)
		segs++;

	return segs;
}

/*
 * get a reference to a bio, so it won't disappear. the intended use is
 * something like:
 *
 * bio_get(bio);
 * submit_bio(rw, bio);
 * if (bio->bi_flags ...)
 *	do_something
 * bio_put(bio);
 *
 * without the bio_get(), it could potentially complete I/O before submit_bio
 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 * runs
 */
static inline void bio_get(struct bio *bio)
{
	bio->bi_flags |= (1 << BIO_REFFED);
	smp_mb__before_atomic();
	atomic_inc(&bio->__bi_cnt);
}

static inline void bio_cnt_set(struct bio *bio, unsigned int count)
{
	if (count != 1) {
		bio->bi_flags |= (1 << BIO_REFFED);
		smp_mb();
	}
	atomic_set(&bio->__bi_cnt, count);
}

static inline bool bio_flagged(struct bio *bio, unsigned int bit)
{
	return (bio->bi_flags & (1U << bit)) != 0;
}

static inline void bio_set_flag(struct bio *bio, unsigned int bit)
{
	bio->bi_flags |= (1U << bit);
}

static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
{
	bio->bi_flags &= ~(1U << bit);
}

static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
{
	*bv = bio_iovec(bio);
}

static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
{
	struct bvec_iter iter = bio->bi_iter;
	int idx;

	if (unlikely(!bio_multiple_segments(bio))) {
		*bv = bio_iovec(bio);
		return;
	}

	bio_advance_iter(bio, &iter, iter.bi_size);

	if (!iter.bi_bvec_done)
		idx = iter.bi_idx - 1;
	else	/* in the middle of bvec */
		idx = iter.bi_idx;

	*bv = bio->bi_io_vec[idx];

	/*
	 * iter.bi_bvec_done records actual length of the last bvec
	 * if this bio ends in the middle of one io vector
	 */
	if (iter.bi_bvec_done)
		bv->bv_len = iter.bi_bvec_done;
}

static inline struct bio_vec *bio_first_bvec_all(struct bio *bio)
{
	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
	return bio->bi_io_vec;
}

static inline struct page *bio_first_page_all(struct bio *bio)
{
	return bio_first_bvec_all(bio)->bv_page;
}

static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
{
	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
	return &bio->bi_io_vec[bio->bi_vcnt - 1];
}

enum bip_flags {
	BIP_BLOCK_INTEGRITY	= 1 << 0, /* block layer owns integrity data */
	BIP_MAPPED_INTEGRITY	= 1 << 1, /* ref tag has been remapped */
	BIP_CTRL_NOCHECK	= 1 << 2, /* disable HBA integrity checking */
	BIP_DISK_NOCHECK	= 1 << 3, /* disable disk integrity checking */
	BIP_IP_CHECKSUM		= 1 << 4, /* IP checksum */
};

/*
 * bio integrity payload
 */
struct bio_integrity_payload {
	struct bio		*bip_bio;	/* parent bio */

	struct bvec_iter	bip_iter;

	unsigned short		bip_slab;	/* slab the bip came from */
	unsigned short		bip_vcnt;	/* # of integrity bio_vecs */
	unsigned short		bip_max_vcnt;	/* integrity bio_vec slots */
	unsigned short		bip_flags;	/* control flags */

	struct bvec_iter	bio_iter;	/* for rewinding parent bio */

	struct work_struct	bip_work;	/* I/O completion */

	struct bio_vec		*bip_vec;
	struct bio_vec		bip_inline_vecs[0];/* embedded bvec array */
};

#if defined(CONFIG_BLK_DEV_INTEGRITY)

static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
{
	if (bio->bi_opf & REQ_INTEGRITY)
		return bio->bi_integrity;

	return NULL;
}

static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
{
	struct bio_integrity_payload *bip = bio_integrity(bio);

	if (bip)
		return bip->bip_flags & flag;

	return false;
}

static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
{
	return bip->bip_iter.bi_sector;
}

static inline void bip_set_seed(struct bio_integrity_payload *bip,
				sector_t seed)
{
	bip->bip_iter.bi_sector = seed;
}

#endif /* CONFIG_BLK_DEV_INTEGRITY */

extern void bio_trim(struct bio *bio, int offset, int size);
extern struct bio *bio_split(struct bio *bio, int sectors,
			     gfp_t gfp, struct bio_set *bs);

/**
 * bio_next_split - get next @sectors from a bio, splitting if necessary
 * @bio:	bio to split
 * @sectors:	number of sectors to split from the front of @bio
 * @gfp:	gfp mask
 * @bs:		bio set to allocate from
 *
 * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 * than @sectors, returns the original bio unchanged.
 */
static inline struct bio *bio_next_split(struct bio *bio, int sectors,
					 gfp_t gfp, struct bio_set *bs)
{
	if (sectors >= bio_sectors(bio))
		return bio;

	return bio_split(bio, sectors, gfp, bs);
}

enum {
	BIOSET_NEED_BVECS = BIT(0),
	BIOSET_NEED_RESCUER = BIT(1),
};
extern int bioset_init(struct bio_set *, unsigned int, unsigned int, int flags);
extern void bioset_exit(struct bio_set *);
extern int biovec_init_pool(mempool_t *pool, int pool_entries);
extern int bioset_init_from_src(struct bio_set *bs, struct bio_set *src);

extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
extern void bio_put(struct bio *);

extern void __bio_clone_fast(struct bio *, struct bio *);
extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);

extern struct bio_set fs_bio_set;

static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
{
	return bio_alloc_bioset(gfp_mask, nr_iovecs, &fs_bio_set);
}

static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
{
	return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
}

extern blk_qc_t submit_bio(struct bio *);

extern void bio_endio(struct bio *);

static inline void bio_io_error(struct bio *bio)
{
	bio->bi_status = BLK_STS_IOERR;
	bio_endio(bio);
}

static inline void bio_wouldblock_error(struct bio *bio)
{
	bio->bi_status = BLK_STS_AGAIN;
	bio_endio(bio);
}

struct request_queue;
extern int bio_phys_segments(struct request_queue *, struct bio *);

extern int submit_bio_wait(struct bio *bio);
extern void bio_advance(struct bio *, unsigned);

extern void bio_init(struct bio *bio, struct bio_vec *table,
		     unsigned short max_vecs);
extern void bio_uninit(struct bio *);
extern void bio_reset(struct bio *);
void bio_chain(struct bio *, struct bio *);

extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
			   unsigned int, unsigned int);
bool __bio_try_merge_page(struct bio *bio, struct page *page,
		unsigned int len, unsigned int off, bool *same_page);
void __bio_add_page(struct bio *bio, struct page *page,
		unsigned int len, unsigned int off);
int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
struct rq_map_data;
extern struct bio *bio_map_user_iov(struct request_queue *,
				    struct iov_iter *, gfp_t);
extern void bio_unmap_user(struct bio *);
extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
				gfp_t);
extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
				 gfp_t, int);
extern void bio_set_pages_dirty(struct bio *bio);
extern void bio_check_pages_dirty(struct bio *bio);

void generic_start_io_acct(struct request_queue *q, int op,
				unsigned long sectors, struct hd_struct *part);
void generic_end_io_acct(struct request_queue *q, int op,
				struct hd_struct *part,
				unsigned long start_time);

#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
# error	"You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
#endif
#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
extern void bio_flush_dcache_pages(struct bio *bi);
#else
static inline void bio_flush_dcache_pages(struct bio *bi)
{
}
#endif

extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
			       struct bio *src, struct bvec_iter *src_iter);
extern void bio_copy_data(struct bio *dst, struct bio *src);
extern void bio_list_copy_data(struct bio *dst, struct bio *src);
extern void bio_free_pages(struct bio *bio);

extern struct bio *bio_copy_user_iov(struct request_queue *,
				     struct rq_map_data *,
				     struct iov_iter *,
				     gfp_t);
extern int bio_uncopy_user(struct bio *);
void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter);

static inline void zero_fill_bio(struct bio *bio)
{
	zero_fill_bio_iter(bio, bio->bi_iter);
}

extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
extern unsigned int bvec_nr_vecs(unsigned short idx);
extern const char *bio_devname(struct bio *bio, char *buffer);

#define bio_set_dev(bio, bdev) 			\
do {						\
	if ((bio)->bi_disk != (bdev)->bd_disk)	\
		bio_clear_flag(bio, BIO_THROTTLED);\
	(bio)->bi_disk = (bdev)->bd_disk;	\
	(bio)->bi_partno = (bdev)->bd_partno;	\
	bio_associate_blkg(bio);		\
} while (0)

#define bio_copy_dev(dst, src)			\
do {						\
	(dst)->bi_disk = (src)->bi_disk;	\
	(dst)->bi_partno = (src)->bi_partno;	\
	bio_clone_blkg_association(dst, src);	\
} while (0)

#define bio_dev(bio) \
	disk_devt((bio)->bi_disk)

#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
void bio_associate_blkg_from_page(struct bio *bio, struct page *page);
#else
static inline void bio_associate_blkg_from_page(struct bio *bio,
						struct page *page) { }
#endif

#ifdef CONFIG_BLK_CGROUP
void bio_disassociate_blkg(struct bio *bio);
void bio_associate_blkg(struct bio *bio);
void bio_associate_blkg_from_css(struct bio *bio,
				 struct cgroup_subsys_state *css);
void bio_clone_blkg_association(struct bio *dst, struct bio *src);
#else	/* CONFIG_BLK_CGROUP */
static inline void bio_disassociate_blkg(struct bio *bio) { }
static inline void bio_associate_blkg(struct bio *bio) { }
static inline void bio_associate_blkg_from_css(struct bio *bio,
					       struct cgroup_subsys_state *css)
{ }
static inline void bio_clone_blkg_association(struct bio *dst,
					      struct bio *src) { }
#endif	/* CONFIG_BLK_CGROUP */

#ifdef CONFIG_HIGHMEM
/*
 * remember never ever reenable interrupts between a bvec_kmap_irq and
 * bvec_kunmap_irq!
 */
static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
{
	unsigned long addr;

	/*
	 * might not be a highmem page, but the preempt/irq count
	 * balancing is a lot nicer this way
	 */
	local_irq_save(*flags);
	addr = (unsigned long) kmap_atomic(bvec->bv_page);

	BUG_ON(addr & ~PAGE_MASK);

	return (char *) addr + bvec->bv_offset;
}

static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
{
	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;

	kunmap_atomic((void *) ptr);
	local_irq_restore(*flags);
}

#else
static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
{
	return page_address(bvec->bv_page) + bvec->bv_offset;
}

static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
{
	*flags = 0;
}
#endif

/*
 * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 *
 * A bio_list anchors a singly-linked list of bios chained through the bi_next
 * member of the bio.  The bio_list also caches the last list member to allow
 * fast access to the tail.
 */
struct bio_list {
	struct bio *head;
	struct bio *tail;
};

static inline int bio_list_empty(const struct bio_list *bl)
{
	return bl->head == NULL;
}

static inline void bio_list_init(struct bio_list *bl)
{
	bl->head = bl->tail = NULL;
}

#define BIO_EMPTY_LIST	{ NULL, NULL }

#define bio_list_for_each(bio, bl) \
	for (bio = (bl)->head; bio; bio = bio->bi_next)

static inline unsigned bio_list_size(const struct bio_list *bl)
{
	unsigned sz = 0;
	struct bio *bio;

	bio_list_for_each(bio, bl)
		sz++;

	return sz;
}

static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
{
	bio->bi_next = NULL;

	if (bl->tail)
		bl->tail->bi_next = bio;
	else
		bl->head = bio;

	bl->tail = bio;
}

static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
{
	bio->bi_next = bl->head;

	bl->head = bio;

	if (!bl->tail)
		bl->tail = bio;
}

static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
{
	if (!bl2->head)
		return;

	if (bl->tail)
		bl->tail->bi_next = bl2->head;
	else
		bl->head = bl2->head;

	bl->tail = bl2->tail;
}

static inline void bio_list_merge_head(struct bio_list *bl,
				       struct bio_list *bl2)
{
	if (!bl2->head)
		return;

	if (bl->head)
		bl2->tail->bi_next = bl->head;
	else
		bl->tail = bl2->tail;

	bl->head = bl2->head;
}

static inline struct bio *bio_list_peek(struct bio_list *bl)
{
	return bl->head;
}

static inline struct bio *bio_list_pop(struct bio_list *bl)
{
	struct bio *bio = bl->head;

	if (bio) {
		bl->head = bl->head->bi_next;
		if (!bl->head)
			bl->tail = NULL;

		bio->bi_next = NULL;
	}

	return bio;
}

static inline struct bio *bio_list_get(struct bio_list *bl)
{
	struct bio *bio = bl->head;

	bl->head = bl->tail = NULL;

	return bio;
}

/*
 * Increment chain count for the bio. Make sure the CHAIN flag update
 * is visible before the raised count.
 */
static inline void bio_inc_remaining(struct bio *bio)
{
	bio_set_flag(bio, BIO_CHAIN);
	smp_mb__before_atomic();
	atomic_inc(&bio->__bi_remaining);
}

/*
 * bio_set is used to allow other portions of the IO system to
 * allocate their own private memory pools for bio and iovec structures.
 * These memory pools in turn all allocate from the bio_slab
 * and the bvec_slabs[].
 */
#define BIO_POOL_SIZE 2

struct bio_set {
	struct kmem_cache *bio_slab;
	unsigned int front_pad;

	mempool_t bio_pool;
	mempool_t bvec_pool;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
	mempool_t bio_integrity_pool;
	mempool_t bvec_integrity_pool;
#endif

	/*
	 * Deadlock avoidance for stacking block drivers: see comments in
	 * bio_alloc_bioset() for details
	 */
	spinlock_t		rescue_lock;
	struct bio_list		rescue_list;
	struct work_struct	rescue_work;
	struct workqueue_struct	*rescue_workqueue;
};

struct biovec_slab {
	int nr_vecs;
	char *name;
	struct kmem_cache *slab;
};

static inline bool bioset_initialized(struct bio_set *bs)
{
	return bs->bio_slab != NULL;
}

/*
 * a small number of entries is fine, not going to be performance critical.
 * basically we just need to survive
 */
#define BIO_SPLIT_ENTRIES 2

#if defined(CONFIG_BLK_DEV_INTEGRITY)

#define bip_for_each_vec(bvl, bip, iter)				\
	for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)

#define bio_for_each_integrity_vec(_bvl, _bio, _iter)			\
	for_each_bio(_bio)						\
		bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)

extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
extern bool bio_integrity_prep(struct bio *);
extern void bio_integrity_advance(struct bio *, unsigned int);
extern void bio_integrity_trim(struct bio *);
extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
extern int bioset_integrity_create(struct bio_set *, int);
extern void bioset_integrity_free(struct bio_set *);
extern void bio_integrity_init(void);

#else /* CONFIG_BLK_DEV_INTEGRITY */

static inline void *bio_integrity(struct bio *bio)
{
	return NULL;
}

static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
{
	return 0;
}

static inline void bioset_integrity_free (struct bio_set *bs)
{
	return;
}

static inline bool bio_integrity_prep(struct bio *bio)
{
	return true;
}

static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
				      gfp_t gfp_mask)
{
	return 0;
}

static inline void bio_integrity_advance(struct bio *bio,
					 unsigned int bytes_done)
{
	return;
}

static inline void bio_integrity_trim(struct bio *bio)
{
	return;
}

static inline void bio_integrity_init(void)
{
	return;
}

static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
{
	return false;
}

static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
								unsigned int nr)
{
	return ERR_PTR(-EINVAL);
}

static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
					unsigned int len, unsigned int offset)
{
	return 0;
}

#endif /* CONFIG_BLK_DEV_INTEGRITY */

/*
 * Mark a bio as polled. Note that for async polled IO, the caller must
 * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
 * We cannot block waiting for requests on polled IO, as those completions
 * must be found by the caller. This is different than IRQ driven IO, where
 * it's safe to wait for IO to complete.
 */
static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
{
	bio->bi_opf |= REQ_HIPRI;
	if (!is_sync_kiocb(kiocb))
		bio->bi_opf |= REQ_NOWAIT;
}

#endif /* CONFIG_BLOCK */
#endif /* __LINUX_BIO_H */