xref: /openbmc/linux/include/linux/bio.h (revision ef833eab)
1 /*
2  * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  *
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public Licens
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
17  */
18 #ifndef __LINUX_BIO_H
19 #define __LINUX_BIO_H
20 
21 #include <linux/highmem.h>
22 #include <linux/mempool.h>
23 #include <linux/ioprio.h>
24 #include <linux/bug.h>
25 
26 #ifdef CONFIG_BLOCK
27 
28 #include <asm/io.h>
29 
30 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
31 #include <linux/blk_types.h>
32 
33 #define BIO_DEBUG
34 
35 #ifdef BIO_DEBUG
36 #define BIO_BUG_ON	BUG_ON
37 #else
38 #define BIO_BUG_ON
39 #endif
40 
41 #ifdef CONFIG_THP_SWAP
42 #if HPAGE_PMD_NR > 256
43 #define BIO_MAX_PAGES		HPAGE_PMD_NR
44 #else
45 #define BIO_MAX_PAGES		256
46 #endif
47 #else
48 #define BIO_MAX_PAGES		256
49 #endif
50 
51 #define bio_prio(bio)			(bio)->bi_ioprio
52 #define bio_set_prio(bio, prio)		((bio)->bi_ioprio = prio)
53 
54 #define bio_iter_iovec(bio, iter)				\
55 	bvec_iter_bvec((bio)->bi_io_vec, (iter))
56 
57 #define bio_iter_page(bio, iter)				\
58 	bvec_iter_page((bio)->bi_io_vec, (iter))
59 #define bio_iter_len(bio, iter)					\
60 	bvec_iter_len((bio)->bi_io_vec, (iter))
61 #define bio_iter_offset(bio, iter)				\
62 	bvec_iter_offset((bio)->bi_io_vec, (iter))
63 
64 #define bio_page(bio)		bio_iter_page((bio), (bio)->bi_iter)
65 #define bio_offset(bio)		bio_iter_offset((bio), (bio)->bi_iter)
66 #define bio_iovec(bio)		bio_iter_iovec((bio), (bio)->bi_iter)
67 
68 #define bio_multiple_segments(bio)				\
69 	((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
70 #define bio_sectors(bio)	((bio)->bi_iter.bi_size >> 9)
71 #define bio_end_sector(bio)	((bio)->bi_iter.bi_sector + bio_sectors((bio)))
72 
73 /*
74  * Return the data direction, READ or WRITE.
75  */
76 #define bio_data_dir(bio) \
77 	(op_is_write(bio_op(bio)) ? WRITE : READ)
78 
79 /*
80  * Check whether this bio carries any data or not. A NULL bio is allowed.
81  */
82 static inline bool bio_has_data(struct bio *bio)
83 {
84 	if (bio &&
85 	    bio->bi_iter.bi_size &&
86 	    bio_op(bio) != REQ_OP_DISCARD &&
87 	    bio_op(bio) != REQ_OP_SECURE_ERASE &&
88 	    bio_op(bio) != REQ_OP_WRITE_ZEROES)
89 		return true;
90 
91 	return false;
92 }
93 
94 static inline bool bio_no_advance_iter(struct bio *bio)
95 {
96 	return bio_op(bio) == REQ_OP_DISCARD ||
97 	       bio_op(bio) == REQ_OP_SECURE_ERASE ||
98 	       bio_op(bio) == REQ_OP_WRITE_SAME ||
99 	       bio_op(bio) == REQ_OP_WRITE_ZEROES;
100 }
101 
102 static inline bool bio_mergeable(struct bio *bio)
103 {
104 	if (bio->bi_opf & REQ_NOMERGE_FLAGS)
105 		return false;
106 
107 	return true;
108 }
109 
110 static inline unsigned int bio_cur_bytes(struct bio *bio)
111 {
112 	if (bio_has_data(bio))
113 		return bio_iovec(bio).bv_len;
114 	else /* dataless requests such as discard */
115 		return bio->bi_iter.bi_size;
116 }
117 
118 static inline void *bio_data(struct bio *bio)
119 {
120 	if (bio_has_data(bio))
121 		return page_address(bio_page(bio)) + bio_offset(bio);
122 
123 	return NULL;
124 }
125 
126 /*
127  * will die
128  */
129 #define bvec_to_phys(bv)	(page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
130 
131 /*
132  * queues that have highmem support enabled may still need to revert to
133  * PIO transfers occasionally and thus map high pages temporarily. For
134  * permanent PIO fall back, user is probably better off disabling highmem
135  * I/O completely on that queue (see ide-dma for example)
136  */
137 #define __bio_kmap_atomic(bio, iter)				\
138 	(kmap_atomic(bio_iter_iovec((bio), (iter)).bv_page) +	\
139 		bio_iter_iovec((bio), (iter)).bv_offset)
140 
141 #define __bio_kunmap_atomic(addr)	kunmap_atomic(addr)
142 
143 /*
144  * merge helpers etc
145  */
146 
147 /* Default implementation of BIOVEC_PHYS_MERGEABLE */
148 #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
149 	((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
150 
151 /*
152  * allow arch override, for eg virtualized architectures (put in asm/io.h)
153  */
154 #ifndef BIOVEC_PHYS_MERGEABLE
155 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
156 	__BIOVEC_PHYS_MERGEABLE(vec1, vec2)
157 #endif
158 
159 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
160 	(((addr1) | (mask)) == (((addr2) - 1) | (mask)))
161 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
162 	__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
163 
164 /*
165  * drivers should _never_ use the all version - the bio may have been split
166  * before it got to the driver and the driver won't own all of it
167  */
168 #define bio_for_each_segment_all(bvl, bio, i)				\
169 	for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
170 
171 static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
172 				    unsigned bytes)
173 {
174 	iter->bi_sector += bytes >> 9;
175 
176 	if (bio_no_advance_iter(bio)) {
177 		iter->bi_size -= bytes;
178 		iter->bi_done += bytes;
179 	} else {
180 		bvec_iter_advance(bio->bi_io_vec, iter, bytes);
181 		/* TODO: It is reasonable to complete bio with error here. */
182 	}
183 }
184 
185 static inline bool bio_rewind_iter(struct bio *bio, struct bvec_iter *iter,
186 		unsigned int bytes)
187 {
188 	iter->bi_sector -= bytes >> 9;
189 
190 	if (bio_no_advance_iter(bio)) {
191 		iter->bi_size += bytes;
192 		iter->bi_done -= bytes;
193 		return true;
194 	}
195 
196 	return bvec_iter_rewind(bio->bi_io_vec, iter, bytes);
197 }
198 
199 #define __bio_for_each_segment(bvl, bio, iter, start)			\
200 	for (iter = (start);						\
201 	     (iter).bi_size &&						\
202 		((bvl = bio_iter_iovec((bio), (iter))), 1);		\
203 	     bio_advance_iter((bio), &(iter), (bvl).bv_len))
204 
205 #define bio_for_each_segment(bvl, bio, iter)				\
206 	__bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
207 
208 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
209 
210 static inline unsigned bio_segments(struct bio *bio)
211 {
212 	unsigned segs = 0;
213 	struct bio_vec bv;
214 	struct bvec_iter iter;
215 
216 	/*
217 	 * We special case discard/write same/write zeroes, because they
218 	 * interpret bi_size differently:
219 	 */
220 
221 	switch (bio_op(bio)) {
222 	case REQ_OP_DISCARD:
223 	case REQ_OP_SECURE_ERASE:
224 	case REQ_OP_WRITE_ZEROES:
225 		return 0;
226 	case REQ_OP_WRITE_SAME:
227 		return 1;
228 	default:
229 		break;
230 	}
231 
232 	bio_for_each_segment(bv, bio, iter)
233 		segs++;
234 
235 	return segs;
236 }
237 
238 /*
239  * get a reference to a bio, so it won't disappear. the intended use is
240  * something like:
241  *
242  * bio_get(bio);
243  * submit_bio(rw, bio);
244  * if (bio->bi_flags ...)
245  *	do_something
246  * bio_put(bio);
247  *
248  * without the bio_get(), it could potentially complete I/O before submit_bio
249  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
250  * runs
251  */
252 static inline void bio_get(struct bio *bio)
253 {
254 	bio->bi_flags |= (1 << BIO_REFFED);
255 	smp_mb__before_atomic();
256 	atomic_inc(&bio->__bi_cnt);
257 }
258 
259 static inline void bio_cnt_set(struct bio *bio, unsigned int count)
260 {
261 	if (count != 1) {
262 		bio->bi_flags |= (1 << BIO_REFFED);
263 		smp_mb__before_atomic();
264 	}
265 	atomic_set(&bio->__bi_cnt, count);
266 }
267 
268 static inline bool bio_flagged(struct bio *bio, unsigned int bit)
269 {
270 	return (bio->bi_flags & (1U << bit)) != 0;
271 }
272 
273 static inline void bio_set_flag(struct bio *bio, unsigned int bit)
274 {
275 	bio->bi_flags |= (1U << bit);
276 }
277 
278 static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
279 {
280 	bio->bi_flags &= ~(1U << bit);
281 }
282 
283 static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
284 {
285 	*bv = bio_iovec(bio);
286 }
287 
288 static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
289 {
290 	struct bvec_iter iter = bio->bi_iter;
291 	int idx;
292 
293 	if (unlikely(!bio_multiple_segments(bio))) {
294 		*bv = bio_iovec(bio);
295 		return;
296 	}
297 
298 	bio_advance_iter(bio, &iter, iter.bi_size);
299 
300 	if (!iter.bi_bvec_done)
301 		idx = iter.bi_idx - 1;
302 	else	/* in the middle of bvec */
303 		idx = iter.bi_idx;
304 
305 	*bv = bio->bi_io_vec[idx];
306 
307 	/*
308 	 * iter.bi_bvec_done records actual length of the last bvec
309 	 * if this bio ends in the middle of one io vector
310 	 */
311 	if (iter.bi_bvec_done)
312 		bv->bv_len = iter.bi_bvec_done;
313 }
314 
315 enum bip_flags {
316 	BIP_BLOCK_INTEGRITY	= 1 << 0, /* block layer owns integrity data */
317 	BIP_MAPPED_INTEGRITY	= 1 << 1, /* ref tag has been remapped */
318 	BIP_CTRL_NOCHECK	= 1 << 2, /* disable HBA integrity checking */
319 	BIP_DISK_NOCHECK	= 1 << 3, /* disable disk integrity checking */
320 	BIP_IP_CHECKSUM		= 1 << 4, /* IP checksum */
321 };
322 
323 /*
324  * bio integrity payload
325  */
326 struct bio_integrity_payload {
327 	struct bio		*bip_bio;	/* parent bio */
328 
329 	struct bvec_iter	bip_iter;
330 
331 	unsigned short		bip_slab;	/* slab the bip came from */
332 	unsigned short		bip_vcnt;	/* # of integrity bio_vecs */
333 	unsigned short		bip_max_vcnt;	/* integrity bio_vec slots */
334 	unsigned short		bip_flags;	/* control flags */
335 
336 	struct work_struct	bip_work;	/* I/O completion */
337 
338 	struct bio_vec		*bip_vec;
339 	struct bio_vec		bip_inline_vecs[0];/* embedded bvec array */
340 };
341 
342 #if defined(CONFIG_BLK_DEV_INTEGRITY)
343 
344 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
345 {
346 	if (bio->bi_opf & REQ_INTEGRITY)
347 		return bio->bi_integrity;
348 
349 	return NULL;
350 }
351 
352 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
353 {
354 	struct bio_integrity_payload *bip = bio_integrity(bio);
355 
356 	if (bip)
357 		return bip->bip_flags & flag;
358 
359 	return false;
360 }
361 
362 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
363 {
364 	return bip->bip_iter.bi_sector;
365 }
366 
367 static inline void bip_set_seed(struct bio_integrity_payload *bip,
368 				sector_t seed)
369 {
370 	bip->bip_iter.bi_sector = seed;
371 }
372 
373 #endif /* CONFIG_BLK_DEV_INTEGRITY */
374 
375 extern void bio_trim(struct bio *bio, int offset, int size);
376 extern struct bio *bio_split(struct bio *bio, int sectors,
377 			     gfp_t gfp, struct bio_set *bs);
378 
379 /**
380  * bio_next_split - get next @sectors from a bio, splitting if necessary
381  * @bio:	bio to split
382  * @sectors:	number of sectors to split from the front of @bio
383  * @gfp:	gfp mask
384  * @bs:		bio set to allocate from
385  *
386  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
387  * than @sectors, returns the original bio unchanged.
388  */
389 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
390 					 gfp_t gfp, struct bio_set *bs)
391 {
392 	if (sectors >= bio_sectors(bio))
393 		return bio;
394 
395 	return bio_split(bio, sectors, gfp, bs);
396 }
397 
398 extern struct bio_set *bioset_create(unsigned int, unsigned int, int flags);
399 enum {
400 	BIOSET_NEED_BVECS = BIT(0),
401 	BIOSET_NEED_RESCUER = BIT(1),
402 };
403 extern void bioset_free(struct bio_set *);
404 extern mempool_t *biovec_create_pool(int pool_entries);
405 
406 extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
407 extern void bio_put(struct bio *);
408 
409 extern void __bio_clone_fast(struct bio *, struct bio *);
410 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
411 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
412 
413 extern struct bio_set *fs_bio_set;
414 
415 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
416 {
417 	return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
418 }
419 
420 static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
421 {
422 	return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
423 }
424 
425 static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
426 {
427 	return bio_clone_bioset(bio, gfp_mask, NULL);
428 
429 }
430 
431 extern blk_qc_t submit_bio(struct bio *);
432 
433 extern void bio_endio(struct bio *);
434 
435 static inline void bio_io_error(struct bio *bio)
436 {
437 	bio->bi_status = BLK_STS_IOERR;
438 	bio_endio(bio);
439 }
440 
441 static inline void bio_wouldblock_error(struct bio *bio)
442 {
443 	bio->bi_status = BLK_STS_AGAIN;
444 	bio_endio(bio);
445 }
446 
447 struct request_queue;
448 extern int bio_phys_segments(struct request_queue *, struct bio *);
449 
450 extern int submit_bio_wait(struct bio *bio);
451 extern void bio_advance(struct bio *, unsigned);
452 
453 extern void bio_init(struct bio *bio, struct bio_vec *table,
454 		     unsigned short max_vecs);
455 extern void bio_uninit(struct bio *);
456 extern void bio_reset(struct bio *);
457 void bio_chain(struct bio *, struct bio *);
458 
459 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
460 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
461 			   unsigned int, unsigned int);
462 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
463 struct rq_map_data;
464 extern struct bio *bio_map_user_iov(struct request_queue *,
465 				    const struct iov_iter *, gfp_t);
466 extern void bio_unmap_user(struct bio *);
467 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
468 				gfp_t);
469 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
470 				 gfp_t, int);
471 extern void bio_set_pages_dirty(struct bio *bio);
472 extern void bio_check_pages_dirty(struct bio *bio);
473 
474 void generic_start_io_acct(struct request_queue *q, int rw,
475 				unsigned long sectors, struct hd_struct *part);
476 void generic_end_io_acct(struct request_queue *q, int rw,
477 				struct hd_struct *part,
478 				unsigned long start_time);
479 
480 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
481 # error	"You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
482 #endif
483 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
484 extern void bio_flush_dcache_pages(struct bio *bi);
485 #else
486 static inline void bio_flush_dcache_pages(struct bio *bi)
487 {
488 }
489 #endif
490 
491 extern void bio_copy_data(struct bio *dst, struct bio *src);
492 extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
493 extern void bio_free_pages(struct bio *bio);
494 
495 extern struct bio *bio_copy_user_iov(struct request_queue *,
496 				     struct rq_map_data *,
497 				     const struct iov_iter *,
498 				     gfp_t);
499 extern int bio_uncopy_user(struct bio *);
500 void zero_fill_bio(struct bio *bio);
501 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
502 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
503 extern unsigned int bvec_nr_vecs(unsigned short idx);
504 
505 #define bio_set_dev(bio, bdev) 			\
506 do {						\
507 	(bio)->bi_disk = (bdev)->bd_disk;	\
508 	(bio)->bi_partno = (bdev)->bd_partno;	\
509 } while (0)
510 
511 #define bio_copy_dev(dst, src)			\
512 do {						\
513 	(dst)->bi_disk = (src)->bi_disk;	\
514 	(dst)->bi_partno = (src)->bi_partno;	\
515 } while (0)
516 
517 #define bio_dev(bio) \
518 	disk_devt((bio)->bi_disk)
519 
520 #define bio_devname(bio, buf) \
521 	__bdevname(bio_dev(bio), (buf))
522 
523 #ifdef CONFIG_BLK_CGROUP
524 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
525 int bio_associate_current(struct bio *bio);
526 void bio_disassociate_task(struct bio *bio);
527 void bio_clone_blkcg_association(struct bio *dst, struct bio *src);
528 #else	/* CONFIG_BLK_CGROUP */
529 static inline int bio_associate_blkcg(struct bio *bio,
530 			struct cgroup_subsys_state *blkcg_css) { return 0; }
531 static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
532 static inline void bio_disassociate_task(struct bio *bio) { }
533 static inline void bio_clone_blkcg_association(struct bio *dst,
534 			struct bio *src) { }
535 #endif	/* CONFIG_BLK_CGROUP */
536 
537 #ifdef CONFIG_HIGHMEM
538 /*
539  * remember never ever reenable interrupts between a bvec_kmap_irq and
540  * bvec_kunmap_irq!
541  */
542 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
543 {
544 	unsigned long addr;
545 
546 	/*
547 	 * might not be a highmem page, but the preempt/irq count
548 	 * balancing is a lot nicer this way
549 	 */
550 	local_irq_save(*flags);
551 	addr = (unsigned long) kmap_atomic(bvec->bv_page);
552 
553 	BUG_ON(addr & ~PAGE_MASK);
554 
555 	return (char *) addr + bvec->bv_offset;
556 }
557 
558 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
559 {
560 	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
561 
562 	kunmap_atomic((void *) ptr);
563 	local_irq_restore(*flags);
564 }
565 
566 #else
567 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
568 {
569 	return page_address(bvec->bv_page) + bvec->bv_offset;
570 }
571 
572 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
573 {
574 	*flags = 0;
575 }
576 #endif
577 
578 static inline char *__bio_kmap_irq(struct bio *bio, struct bvec_iter iter,
579 				   unsigned long *flags)
580 {
581 	return bvec_kmap_irq(&bio_iter_iovec(bio, iter), flags);
582 }
583 #define __bio_kunmap_irq(buf, flags)	bvec_kunmap_irq(buf, flags)
584 
585 #define bio_kmap_irq(bio, flags) \
586 	__bio_kmap_irq((bio), (bio)->bi_iter, (flags))
587 #define bio_kunmap_irq(buf,flags)	__bio_kunmap_irq(buf, flags)
588 
589 /*
590  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
591  *
592  * A bio_list anchors a singly-linked list of bios chained through the bi_next
593  * member of the bio.  The bio_list also caches the last list member to allow
594  * fast access to the tail.
595  */
596 struct bio_list {
597 	struct bio *head;
598 	struct bio *tail;
599 };
600 
601 static inline int bio_list_empty(const struct bio_list *bl)
602 {
603 	return bl->head == NULL;
604 }
605 
606 static inline void bio_list_init(struct bio_list *bl)
607 {
608 	bl->head = bl->tail = NULL;
609 }
610 
611 #define BIO_EMPTY_LIST	{ NULL, NULL }
612 
613 #define bio_list_for_each(bio, bl) \
614 	for (bio = (bl)->head; bio; bio = bio->bi_next)
615 
616 static inline unsigned bio_list_size(const struct bio_list *bl)
617 {
618 	unsigned sz = 0;
619 	struct bio *bio;
620 
621 	bio_list_for_each(bio, bl)
622 		sz++;
623 
624 	return sz;
625 }
626 
627 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
628 {
629 	bio->bi_next = NULL;
630 
631 	if (bl->tail)
632 		bl->tail->bi_next = bio;
633 	else
634 		bl->head = bio;
635 
636 	bl->tail = bio;
637 }
638 
639 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
640 {
641 	bio->bi_next = bl->head;
642 
643 	bl->head = bio;
644 
645 	if (!bl->tail)
646 		bl->tail = bio;
647 }
648 
649 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
650 {
651 	if (!bl2->head)
652 		return;
653 
654 	if (bl->tail)
655 		bl->tail->bi_next = bl2->head;
656 	else
657 		bl->head = bl2->head;
658 
659 	bl->tail = bl2->tail;
660 }
661 
662 static inline void bio_list_merge_head(struct bio_list *bl,
663 				       struct bio_list *bl2)
664 {
665 	if (!bl2->head)
666 		return;
667 
668 	if (bl->head)
669 		bl2->tail->bi_next = bl->head;
670 	else
671 		bl->tail = bl2->tail;
672 
673 	bl->head = bl2->head;
674 }
675 
676 static inline struct bio *bio_list_peek(struct bio_list *bl)
677 {
678 	return bl->head;
679 }
680 
681 static inline struct bio *bio_list_pop(struct bio_list *bl)
682 {
683 	struct bio *bio = bl->head;
684 
685 	if (bio) {
686 		bl->head = bl->head->bi_next;
687 		if (!bl->head)
688 			bl->tail = NULL;
689 
690 		bio->bi_next = NULL;
691 	}
692 
693 	return bio;
694 }
695 
696 static inline struct bio *bio_list_get(struct bio_list *bl)
697 {
698 	struct bio *bio = bl->head;
699 
700 	bl->head = bl->tail = NULL;
701 
702 	return bio;
703 }
704 
705 /*
706  * Increment chain count for the bio. Make sure the CHAIN flag update
707  * is visible before the raised count.
708  */
709 static inline void bio_inc_remaining(struct bio *bio)
710 {
711 	bio_set_flag(bio, BIO_CHAIN);
712 	smp_mb__before_atomic();
713 	atomic_inc(&bio->__bi_remaining);
714 }
715 
716 /*
717  * bio_set is used to allow other portions of the IO system to
718  * allocate their own private memory pools for bio and iovec structures.
719  * These memory pools in turn all allocate from the bio_slab
720  * and the bvec_slabs[].
721  */
722 #define BIO_POOL_SIZE 2
723 
724 struct bio_set {
725 	struct kmem_cache *bio_slab;
726 	unsigned int front_pad;
727 
728 	mempool_t *bio_pool;
729 	mempool_t *bvec_pool;
730 #if defined(CONFIG_BLK_DEV_INTEGRITY)
731 	mempool_t *bio_integrity_pool;
732 	mempool_t *bvec_integrity_pool;
733 #endif
734 
735 	/*
736 	 * Deadlock avoidance for stacking block drivers: see comments in
737 	 * bio_alloc_bioset() for details
738 	 */
739 	spinlock_t		rescue_lock;
740 	struct bio_list		rescue_list;
741 	struct work_struct	rescue_work;
742 	struct workqueue_struct	*rescue_workqueue;
743 };
744 
745 struct biovec_slab {
746 	int nr_vecs;
747 	char *name;
748 	struct kmem_cache *slab;
749 };
750 
751 /*
752  * a small number of entries is fine, not going to be performance critical.
753  * basically we just need to survive
754  */
755 #define BIO_SPLIT_ENTRIES 2
756 
757 #if defined(CONFIG_BLK_DEV_INTEGRITY)
758 
759 #define bip_for_each_vec(bvl, bip, iter)				\
760 	for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
761 
762 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)			\
763 	for_each_bio(_bio)						\
764 		bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
765 
766 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
767 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
768 extern bool bio_integrity_prep(struct bio *);
769 extern void bio_integrity_advance(struct bio *, unsigned int);
770 extern void bio_integrity_trim(struct bio *);
771 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
772 extern int bioset_integrity_create(struct bio_set *, int);
773 extern void bioset_integrity_free(struct bio_set *);
774 extern void bio_integrity_init(void);
775 
776 #else /* CONFIG_BLK_DEV_INTEGRITY */
777 
778 static inline void *bio_integrity(struct bio *bio)
779 {
780 	return NULL;
781 }
782 
783 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
784 {
785 	return 0;
786 }
787 
788 static inline void bioset_integrity_free (struct bio_set *bs)
789 {
790 	return;
791 }
792 
793 static inline bool bio_integrity_prep(struct bio *bio)
794 {
795 	return true;
796 }
797 
798 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
799 				      gfp_t gfp_mask)
800 {
801 	return 0;
802 }
803 
804 static inline void bio_integrity_advance(struct bio *bio,
805 					 unsigned int bytes_done)
806 {
807 	return;
808 }
809 
810 static inline void bio_integrity_trim(struct bio *bio)
811 {
812 	return;
813 }
814 
815 static inline void bio_integrity_init(void)
816 {
817 	return;
818 }
819 
820 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
821 {
822 	return false;
823 }
824 
825 static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
826 								unsigned int nr)
827 {
828 	return ERR_PTR(-EINVAL);
829 }
830 
831 static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
832 					unsigned int len, unsigned int offset)
833 {
834 	return 0;
835 }
836 
837 #endif /* CONFIG_BLK_DEV_INTEGRITY */
838 
839 #endif /* CONFIG_BLOCK */
840 #endif /* __LINUX_BIO_H */
841