xref: /openbmc/linux/include/linux/bio.h (revision 8f762fe5)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
4  */
5 #ifndef __LINUX_BIO_H
6 #define __LINUX_BIO_H
7 
8 #include <linux/highmem.h>
9 #include <linux/mempool.h>
10 #include <linux/ioprio.h>
11 
12 #ifdef CONFIG_BLOCK
13 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
14 #include <linux/blk_types.h>
15 
16 #define BIO_DEBUG
17 
18 #ifdef BIO_DEBUG
19 #define BIO_BUG_ON	BUG_ON
20 #else
21 #define BIO_BUG_ON
22 #endif
23 
24 #define BIO_MAX_PAGES		256
25 
26 #define bio_prio(bio)			(bio)->bi_ioprio
27 #define bio_set_prio(bio, prio)		((bio)->bi_ioprio = prio)
28 
29 #define bio_iter_iovec(bio, iter)				\
30 	bvec_iter_bvec((bio)->bi_io_vec, (iter))
31 
32 #define bio_iter_page(bio, iter)				\
33 	bvec_iter_page((bio)->bi_io_vec, (iter))
34 #define bio_iter_len(bio, iter)					\
35 	bvec_iter_len((bio)->bi_io_vec, (iter))
36 #define bio_iter_offset(bio, iter)				\
37 	bvec_iter_offset((bio)->bi_io_vec, (iter))
38 
39 #define bio_page(bio)		bio_iter_page((bio), (bio)->bi_iter)
40 #define bio_offset(bio)		bio_iter_offset((bio), (bio)->bi_iter)
41 #define bio_iovec(bio)		bio_iter_iovec((bio), (bio)->bi_iter)
42 
43 #define bio_multiple_segments(bio)				\
44 	((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
45 
46 #define bvec_iter_sectors(iter)	((iter).bi_size >> 9)
47 #define bvec_iter_end_sector(iter) ((iter).bi_sector + bvec_iter_sectors((iter)))
48 
49 #define bio_sectors(bio)	bvec_iter_sectors((bio)->bi_iter)
50 #define bio_end_sector(bio)	bvec_iter_end_sector((bio)->bi_iter)
51 
52 /*
53  * Return the data direction, READ or WRITE.
54  */
55 #define bio_data_dir(bio) \
56 	(op_is_write(bio_op(bio)) ? WRITE : READ)
57 
58 /*
59  * Check whether this bio carries any data or not. A NULL bio is allowed.
60  */
61 static inline bool bio_has_data(struct bio *bio)
62 {
63 	if (bio &&
64 	    bio->bi_iter.bi_size &&
65 	    bio_op(bio) != REQ_OP_DISCARD &&
66 	    bio_op(bio) != REQ_OP_SECURE_ERASE &&
67 	    bio_op(bio) != REQ_OP_WRITE_ZEROES)
68 		return true;
69 
70 	return false;
71 }
72 
73 static inline bool bio_no_advance_iter(struct bio *bio)
74 {
75 	return bio_op(bio) == REQ_OP_DISCARD ||
76 	       bio_op(bio) == REQ_OP_SECURE_ERASE ||
77 	       bio_op(bio) == REQ_OP_WRITE_SAME ||
78 	       bio_op(bio) == REQ_OP_WRITE_ZEROES;
79 }
80 
81 static inline bool bio_mergeable(struct bio *bio)
82 {
83 	if (bio->bi_opf & REQ_NOMERGE_FLAGS)
84 		return false;
85 
86 	return true;
87 }
88 
89 static inline unsigned int bio_cur_bytes(struct bio *bio)
90 {
91 	if (bio_has_data(bio))
92 		return bio_iovec(bio).bv_len;
93 	else /* dataless requests such as discard */
94 		return bio->bi_iter.bi_size;
95 }
96 
97 static inline void *bio_data(struct bio *bio)
98 {
99 	if (bio_has_data(bio))
100 		return page_address(bio_page(bio)) + bio_offset(bio);
101 
102 	return NULL;
103 }
104 
105 static inline bool bio_full(struct bio *bio)
106 {
107 	return bio->bi_vcnt >= bio->bi_max_vecs;
108 }
109 
110 static inline bool bio_next_segment(const struct bio *bio,
111 				    struct bvec_iter_all *iter)
112 {
113 	if (iter->idx >= bio->bi_vcnt)
114 		return false;
115 
116 	bvec_advance(&bio->bi_io_vec[iter->idx], iter);
117 	return true;
118 }
119 
120 /*
121  * drivers should _never_ use the all version - the bio may have been split
122  * before it got to the driver and the driver won't own all of it
123  */
124 #define bio_for_each_segment_all(bvl, bio, iter) \
125 	for (bvl = bvec_init_iter_all(&iter); bio_next_segment((bio), &iter); )
126 
127 static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
128 				    unsigned bytes)
129 {
130 	iter->bi_sector += bytes >> 9;
131 
132 	if (bio_no_advance_iter(bio))
133 		iter->bi_size -= bytes;
134 	else
135 		bvec_iter_advance(bio->bi_io_vec, iter, bytes);
136 		/* TODO: It is reasonable to complete bio with error here. */
137 }
138 
139 #define __bio_for_each_segment(bvl, bio, iter, start)			\
140 	for (iter = (start);						\
141 	     (iter).bi_size &&						\
142 		((bvl = bio_iter_iovec((bio), (iter))), 1);		\
143 	     bio_advance_iter((bio), &(iter), (bvl).bv_len))
144 
145 #define bio_for_each_segment(bvl, bio, iter)				\
146 	__bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
147 
148 #define __bio_for_each_bvec(bvl, bio, iter, start)		\
149 	for (iter = (start);						\
150 	     (iter).bi_size &&						\
151 		((bvl = mp_bvec_iter_bvec((bio)->bi_io_vec, (iter))), 1); \
152 	     bio_advance_iter((bio), &(iter), (bvl).bv_len))
153 
154 /* iterate over multi-page bvec */
155 #define bio_for_each_bvec(bvl, bio, iter)			\
156 	__bio_for_each_bvec(bvl, bio, iter, (bio)->bi_iter)
157 
158 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
159 
160 static inline unsigned bio_segments(struct bio *bio)
161 {
162 	unsigned segs = 0;
163 	struct bio_vec bv;
164 	struct bvec_iter iter;
165 
166 	/*
167 	 * We special case discard/write same/write zeroes, because they
168 	 * interpret bi_size differently:
169 	 */
170 
171 	switch (bio_op(bio)) {
172 	case REQ_OP_DISCARD:
173 	case REQ_OP_SECURE_ERASE:
174 	case REQ_OP_WRITE_ZEROES:
175 		return 0;
176 	case REQ_OP_WRITE_SAME:
177 		return 1;
178 	default:
179 		break;
180 	}
181 
182 	bio_for_each_segment(bv, bio, iter)
183 		segs++;
184 
185 	return segs;
186 }
187 
188 /*
189  * get a reference to a bio, so it won't disappear. the intended use is
190  * something like:
191  *
192  * bio_get(bio);
193  * submit_bio(rw, bio);
194  * if (bio->bi_flags ...)
195  *	do_something
196  * bio_put(bio);
197  *
198  * without the bio_get(), it could potentially complete I/O before submit_bio
199  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
200  * runs
201  */
202 static inline void bio_get(struct bio *bio)
203 {
204 	bio->bi_flags |= (1 << BIO_REFFED);
205 	smp_mb__before_atomic();
206 	atomic_inc(&bio->__bi_cnt);
207 }
208 
209 static inline void bio_cnt_set(struct bio *bio, unsigned int count)
210 {
211 	if (count != 1) {
212 		bio->bi_flags |= (1 << BIO_REFFED);
213 		smp_mb__before_atomic();
214 	}
215 	atomic_set(&bio->__bi_cnt, count);
216 }
217 
218 static inline bool bio_flagged(struct bio *bio, unsigned int bit)
219 {
220 	return (bio->bi_flags & (1U << bit)) != 0;
221 }
222 
223 static inline void bio_set_flag(struct bio *bio, unsigned int bit)
224 {
225 	bio->bi_flags |= (1U << bit);
226 }
227 
228 static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
229 {
230 	bio->bi_flags &= ~(1U << bit);
231 }
232 
233 static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
234 {
235 	*bv = bio_iovec(bio);
236 }
237 
238 static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
239 {
240 	struct bvec_iter iter = bio->bi_iter;
241 	int idx;
242 
243 	if (unlikely(!bio_multiple_segments(bio))) {
244 		*bv = bio_iovec(bio);
245 		return;
246 	}
247 
248 	bio_advance_iter(bio, &iter, iter.bi_size);
249 
250 	if (!iter.bi_bvec_done)
251 		idx = iter.bi_idx - 1;
252 	else	/* in the middle of bvec */
253 		idx = iter.bi_idx;
254 
255 	*bv = bio->bi_io_vec[idx];
256 
257 	/*
258 	 * iter.bi_bvec_done records actual length of the last bvec
259 	 * if this bio ends in the middle of one io vector
260 	 */
261 	if (iter.bi_bvec_done)
262 		bv->bv_len = iter.bi_bvec_done;
263 }
264 
265 static inline struct bio_vec *bio_first_bvec_all(struct bio *bio)
266 {
267 	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
268 	return bio->bi_io_vec;
269 }
270 
271 static inline struct page *bio_first_page_all(struct bio *bio)
272 {
273 	return bio_first_bvec_all(bio)->bv_page;
274 }
275 
276 static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
277 {
278 	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
279 	return &bio->bi_io_vec[bio->bi_vcnt - 1];
280 }
281 
282 enum bip_flags {
283 	BIP_BLOCK_INTEGRITY	= 1 << 0, /* block layer owns integrity data */
284 	BIP_MAPPED_INTEGRITY	= 1 << 1, /* ref tag has been remapped */
285 	BIP_CTRL_NOCHECK	= 1 << 2, /* disable HBA integrity checking */
286 	BIP_DISK_NOCHECK	= 1 << 3, /* disable disk integrity checking */
287 	BIP_IP_CHECKSUM		= 1 << 4, /* IP checksum */
288 };
289 
290 /*
291  * bio integrity payload
292  */
293 struct bio_integrity_payload {
294 	struct bio		*bip_bio;	/* parent bio */
295 
296 	struct bvec_iter	bip_iter;
297 
298 	unsigned short		bip_slab;	/* slab the bip came from */
299 	unsigned short		bip_vcnt;	/* # of integrity bio_vecs */
300 	unsigned short		bip_max_vcnt;	/* integrity bio_vec slots */
301 	unsigned short		bip_flags;	/* control flags */
302 
303 	struct bvec_iter	bio_iter;	/* for rewinding parent bio */
304 
305 	struct work_struct	bip_work;	/* I/O completion */
306 
307 	struct bio_vec		*bip_vec;
308 	struct bio_vec		bip_inline_vecs[0];/* embedded bvec array */
309 };
310 
311 #if defined(CONFIG_BLK_DEV_INTEGRITY)
312 
313 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
314 {
315 	if (bio->bi_opf & REQ_INTEGRITY)
316 		return bio->bi_integrity;
317 
318 	return NULL;
319 }
320 
321 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
322 {
323 	struct bio_integrity_payload *bip = bio_integrity(bio);
324 
325 	if (bip)
326 		return bip->bip_flags & flag;
327 
328 	return false;
329 }
330 
331 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
332 {
333 	return bip->bip_iter.bi_sector;
334 }
335 
336 static inline void bip_set_seed(struct bio_integrity_payload *bip,
337 				sector_t seed)
338 {
339 	bip->bip_iter.bi_sector = seed;
340 }
341 
342 #endif /* CONFIG_BLK_DEV_INTEGRITY */
343 
344 extern void bio_trim(struct bio *bio, int offset, int size);
345 extern struct bio *bio_split(struct bio *bio, int sectors,
346 			     gfp_t gfp, struct bio_set *bs);
347 
348 /**
349  * bio_next_split - get next @sectors from a bio, splitting if necessary
350  * @bio:	bio to split
351  * @sectors:	number of sectors to split from the front of @bio
352  * @gfp:	gfp mask
353  * @bs:		bio set to allocate from
354  *
355  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
356  * than @sectors, returns the original bio unchanged.
357  */
358 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
359 					 gfp_t gfp, struct bio_set *bs)
360 {
361 	if (sectors >= bio_sectors(bio))
362 		return bio;
363 
364 	return bio_split(bio, sectors, gfp, bs);
365 }
366 
367 enum {
368 	BIOSET_NEED_BVECS = BIT(0),
369 	BIOSET_NEED_RESCUER = BIT(1),
370 };
371 extern int bioset_init(struct bio_set *, unsigned int, unsigned int, int flags);
372 extern void bioset_exit(struct bio_set *);
373 extern int biovec_init_pool(mempool_t *pool, int pool_entries);
374 extern int bioset_init_from_src(struct bio_set *bs, struct bio_set *src);
375 
376 extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
377 extern void bio_put(struct bio *);
378 
379 extern void __bio_clone_fast(struct bio *, struct bio *);
380 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
381 
382 extern struct bio_set fs_bio_set;
383 
384 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
385 {
386 	return bio_alloc_bioset(gfp_mask, nr_iovecs, &fs_bio_set);
387 }
388 
389 static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
390 {
391 	return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
392 }
393 
394 extern blk_qc_t submit_bio(struct bio *);
395 
396 extern void bio_endio(struct bio *);
397 
398 static inline void bio_io_error(struct bio *bio)
399 {
400 	bio->bi_status = BLK_STS_IOERR;
401 	bio_endio(bio);
402 }
403 
404 static inline void bio_wouldblock_error(struct bio *bio)
405 {
406 	bio->bi_status = BLK_STS_AGAIN;
407 	bio_endio(bio);
408 }
409 
410 struct request_queue;
411 extern int bio_phys_segments(struct request_queue *, struct bio *);
412 
413 extern int submit_bio_wait(struct bio *bio);
414 extern void bio_advance(struct bio *, unsigned);
415 
416 extern void bio_init(struct bio *bio, struct bio_vec *table,
417 		     unsigned short max_vecs);
418 extern void bio_uninit(struct bio *);
419 extern void bio_reset(struct bio *);
420 void bio_chain(struct bio *, struct bio *);
421 
422 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
423 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
424 			   unsigned int, unsigned int);
425 bool __bio_try_merge_page(struct bio *bio, struct page *page,
426 		unsigned int len, unsigned int off, bool same_page);
427 void __bio_add_page(struct bio *bio, struct page *page,
428 		unsigned int len, unsigned int off);
429 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
430 struct rq_map_data;
431 extern struct bio *bio_map_user_iov(struct request_queue *,
432 				    struct iov_iter *, gfp_t);
433 extern void bio_unmap_user(struct bio *);
434 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
435 				gfp_t);
436 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
437 				 gfp_t, int);
438 extern void bio_set_pages_dirty(struct bio *bio);
439 extern void bio_check_pages_dirty(struct bio *bio);
440 
441 void generic_start_io_acct(struct request_queue *q, int op,
442 				unsigned long sectors, struct hd_struct *part);
443 void generic_end_io_acct(struct request_queue *q, int op,
444 				struct hd_struct *part,
445 				unsigned long start_time);
446 
447 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
448 # error	"You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
449 #endif
450 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
451 extern void bio_flush_dcache_pages(struct bio *bi);
452 #else
453 static inline void bio_flush_dcache_pages(struct bio *bi)
454 {
455 }
456 #endif
457 
458 extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
459 			       struct bio *src, struct bvec_iter *src_iter);
460 extern void bio_copy_data(struct bio *dst, struct bio *src);
461 extern void bio_list_copy_data(struct bio *dst, struct bio *src);
462 extern void bio_free_pages(struct bio *bio);
463 
464 extern struct bio *bio_copy_user_iov(struct request_queue *,
465 				     struct rq_map_data *,
466 				     struct iov_iter *,
467 				     gfp_t);
468 extern int bio_uncopy_user(struct bio *);
469 void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter);
470 
471 static inline void zero_fill_bio(struct bio *bio)
472 {
473 	zero_fill_bio_iter(bio, bio->bi_iter);
474 }
475 
476 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
477 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
478 extern unsigned int bvec_nr_vecs(unsigned short idx);
479 extern const char *bio_devname(struct bio *bio, char *buffer);
480 
481 #define bio_set_dev(bio, bdev) 			\
482 do {						\
483 	if ((bio)->bi_disk != (bdev)->bd_disk)	\
484 		bio_clear_flag(bio, BIO_THROTTLED);\
485 	(bio)->bi_disk = (bdev)->bd_disk;	\
486 	(bio)->bi_partno = (bdev)->bd_partno;	\
487 	bio_associate_blkg(bio);		\
488 } while (0)
489 
490 #define bio_copy_dev(dst, src)			\
491 do {						\
492 	(dst)->bi_disk = (src)->bi_disk;	\
493 	(dst)->bi_partno = (src)->bi_partno;	\
494 	bio_clone_blkg_association(dst, src);	\
495 } while (0)
496 
497 #define bio_dev(bio) \
498 	disk_devt((bio)->bi_disk)
499 
500 #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
501 void bio_associate_blkg_from_page(struct bio *bio, struct page *page);
502 #else
503 static inline void bio_associate_blkg_from_page(struct bio *bio,
504 						struct page *page) { }
505 #endif
506 
507 #ifdef CONFIG_BLK_CGROUP
508 void bio_disassociate_blkg(struct bio *bio);
509 void bio_associate_blkg(struct bio *bio);
510 void bio_associate_blkg_from_css(struct bio *bio,
511 				 struct cgroup_subsys_state *css);
512 void bio_clone_blkg_association(struct bio *dst, struct bio *src);
513 #else	/* CONFIG_BLK_CGROUP */
514 static inline void bio_disassociate_blkg(struct bio *bio) { }
515 static inline void bio_associate_blkg(struct bio *bio) { }
516 static inline void bio_associate_blkg_from_css(struct bio *bio,
517 					       struct cgroup_subsys_state *css)
518 { }
519 static inline void bio_clone_blkg_association(struct bio *dst,
520 					      struct bio *src) { }
521 #endif	/* CONFIG_BLK_CGROUP */
522 
523 #ifdef CONFIG_HIGHMEM
524 /*
525  * remember never ever reenable interrupts between a bvec_kmap_irq and
526  * bvec_kunmap_irq!
527  */
528 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
529 {
530 	unsigned long addr;
531 
532 	/*
533 	 * might not be a highmem page, but the preempt/irq count
534 	 * balancing is a lot nicer this way
535 	 */
536 	local_irq_save(*flags);
537 	addr = (unsigned long) kmap_atomic(bvec->bv_page);
538 
539 	BUG_ON(addr & ~PAGE_MASK);
540 
541 	return (char *) addr + bvec->bv_offset;
542 }
543 
544 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
545 {
546 	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
547 
548 	kunmap_atomic((void *) ptr);
549 	local_irq_restore(*flags);
550 }
551 
552 #else
553 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
554 {
555 	return page_address(bvec->bv_page) + bvec->bv_offset;
556 }
557 
558 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
559 {
560 	*flags = 0;
561 }
562 #endif
563 
564 /*
565  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
566  *
567  * A bio_list anchors a singly-linked list of bios chained through the bi_next
568  * member of the bio.  The bio_list also caches the last list member to allow
569  * fast access to the tail.
570  */
571 struct bio_list {
572 	struct bio *head;
573 	struct bio *tail;
574 };
575 
576 static inline int bio_list_empty(const struct bio_list *bl)
577 {
578 	return bl->head == NULL;
579 }
580 
581 static inline void bio_list_init(struct bio_list *bl)
582 {
583 	bl->head = bl->tail = NULL;
584 }
585 
586 #define BIO_EMPTY_LIST	{ NULL, NULL }
587 
588 #define bio_list_for_each(bio, bl) \
589 	for (bio = (bl)->head; bio; bio = bio->bi_next)
590 
591 static inline unsigned bio_list_size(const struct bio_list *bl)
592 {
593 	unsigned sz = 0;
594 	struct bio *bio;
595 
596 	bio_list_for_each(bio, bl)
597 		sz++;
598 
599 	return sz;
600 }
601 
602 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
603 {
604 	bio->bi_next = NULL;
605 
606 	if (bl->tail)
607 		bl->tail->bi_next = bio;
608 	else
609 		bl->head = bio;
610 
611 	bl->tail = bio;
612 }
613 
614 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
615 {
616 	bio->bi_next = bl->head;
617 
618 	bl->head = bio;
619 
620 	if (!bl->tail)
621 		bl->tail = bio;
622 }
623 
624 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
625 {
626 	if (!bl2->head)
627 		return;
628 
629 	if (bl->tail)
630 		bl->tail->bi_next = bl2->head;
631 	else
632 		bl->head = bl2->head;
633 
634 	bl->tail = bl2->tail;
635 }
636 
637 static inline void bio_list_merge_head(struct bio_list *bl,
638 				       struct bio_list *bl2)
639 {
640 	if (!bl2->head)
641 		return;
642 
643 	if (bl->head)
644 		bl2->tail->bi_next = bl->head;
645 	else
646 		bl->tail = bl2->tail;
647 
648 	bl->head = bl2->head;
649 }
650 
651 static inline struct bio *bio_list_peek(struct bio_list *bl)
652 {
653 	return bl->head;
654 }
655 
656 static inline struct bio *bio_list_pop(struct bio_list *bl)
657 {
658 	struct bio *bio = bl->head;
659 
660 	if (bio) {
661 		bl->head = bl->head->bi_next;
662 		if (!bl->head)
663 			bl->tail = NULL;
664 
665 		bio->bi_next = NULL;
666 	}
667 
668 	return bio;
669 }
670 
671 static inline struct bio *bio_list_get(struct bio_list *bl)
672 {
673 	struct bio *bio = bl->head;
674 
675 	bl->head = bl->tail = NULL;
676 
677 	return bio;
678 }
679 
680 /*
681  * Increment chain count for the bio. Make sure the CHAIN flag update
682  * is visible before the raised count.
683  */
684 static inline void bio_inc_remaining(struct bio *bio)
685 {
686 	bio_set_flag(bio, BIO_CHAIN);
687 	smp_mb__before_atomic();
688 	atomic_inc(&bio->__bi_remaining);
689 }
690 
691 /*
692  * bio_set is used to allow other portions of the IO system to
693  * allocate their own private memory pools for bio and iovec structures.
694  * These memory pools in turn all allocate from the bio_slab
695  * and the bvec_slabs[].
696  */
697 #define BIO_POOL_SIZE 2
698 
699 struct bio_set {
700 	struct kmem_cache *bio_slab;
701 	unsigned int front_pad;
702 
703 	mempool_t bio_pool;
704 	mempool_t bvec_pool;
705 #if defined(CONFIG_BLK_DEV_INTEGRITY)
706 	mempool_t bio_integrity_pool;
707 	mempool_t bvec_integrity_pool;
708 #endif
709 
710 	/*
711 	 * Deadlock avoidance for stacking block drivers: see comments in
712 	 * bio_alloc_bioset() for details
713 	 */
714 	spinlock_t		rescue_lock;
715 	struct bio_list		rescue_list;
716 	struct work_struct	rescue_work;
717 	struct workqueue_struct	*rescue_workqueue;
718 };
719 
720 struct biovec_slab {
721 	int nr_vecs;
722 	char *name;
723 	struct kmem_cache *slab;
724 };
725 
726 static inline bool bioset_initialized(struct bio_set *bs)
727 {
728 	return bs->bio_slab != NULL;
729 }
730 
731 /*
732  * a small number of entries is fine, not going to be performance critical.
733  * basically we just need to survive
734  */
735 #define BIO_SPLIT_ENTRIES 2
736 
737 #if defined(CONFIG_BLK_DEV_INTEGRITY)
738 
739 #define bip_for_each_vec(bvl, bip, iter)				\
740 	for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
741 
742 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)			\
743 	for_each_bio(_bio)						\
744 		bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
745 
746 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
747 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
748 extern bool bio_integrity_prep(struct bio *);
749 extern void bio_integrity_advance(struct bio *, unsigned int);
750 extern void bio_integrity_trim(struct bio *);
751 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
752 extern int bioset_integrity_create(struct bio_set *, int);
753 extern void bioset_integrity_free(struct bio_set *);
754 extern void bio_integrity_init(void);
755 
756 #else /* CONFIG_BLK_DEV_INTEGRITY */
757 
758 static inline void *bio_integrity(struct bio *bio)
759 {
760 	return NULL;
761 }
762 
763 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
764 {
765 	return 0;
766 }
767 
768 static inline void bioset_integrity_free (struct bio_set *bs)
769 {
770 	return;
771 }
772 
773 static inline bool bio_integrity_prep(struct bio *bio)
774 {
775 	return true;
776 }
777 
778 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
779 				      gfp_t gfp_mask)
780 {
781 	return 0;
782 }
783 
784 static inline void bio_integrity_advance(struct bio *bio,
785 					 unsigned int bytes_done)
786 {
787 	return;
788 }
789 
790 static inline void bio_integrity_trim(struct bio *bio)
791 {
792 	return;
793 }
794 
795 static inline void bio_integrity_init(void)
796 {
797 	return;
798 }
799 
800 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
801 {
802 	return false;
803 }
804 
805 static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
806 								unsigned int nr)
807 {
808 	return ERR_PTR(-EINVAL);
809 }
810 
811 static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
812 					unsigned int len, unsigned int offset)
813 {
814 	return 0;
815 }
816 
817 #endif /* CONFIG_BLK_DEV_INTEGRITY */
818 
819 /*
820  * Mark a bio as polled. Note that for async polled IO, the caller must
821  * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
822  * We cannot block waiting for requests on polled IO, as those completions
823  * must be found by the caller. This is different than IRQ driven IO, where
824  * it's safe to wait for IO to complete.
825  */
826 static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
827 {
828 	bio->bi_opf |= REQ_HIPRI;
829 	if (!is_sync_kiocb(kiocb))
830 		bio->bi_opf |= REQ_NOWAIT;
831 }
832 
833 #endif /* CONFIG_BLOCK */
834 #endif /* __LINUX_BIO_H */
835