xref: /openbmc/linux/include/linux/bio.h (revision 92a2c6b2)
1 /*
2  * 2.5 block I/O model
3  *
4  * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  *
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public Licens
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
19  */
20 #ifndef __LINUX_BIO_H
21 #define __LINUX_BIO_H
22 
23 #include <linux/highmem.h>
24 #include <linux/mempool.h>
25 #include <linux/ioprio.h>
26 #include <linux/bug.h>
27 
28 #ifdef CONFIG_BLOCK
29 
30 #include <asm/io.h>
31 
32 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
33 #include <linux/blk_types.h>
34 
35 #define BIO_DEBUG
36 
37 #ifdef BIO_DEBUG
38 #define BIO_BUG_ON	BUG_ON
39 #else
40 #define BIO_BUG_ON
41 #endif
42 
43 #define BIO_MAX_PAGES		256
44 #define BIO_MAX_SIZE		(BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
45 #define BIO_MAX_SECTORS		(BIO_MAX_SIZE >> 9)
46 
47 /*
48  * upper 16 bits of bi_rw define the io priority of this bio
49  */
50 #define BIO_PRIO_SHIFT	(8 * sizeof(unsigned long) - IOPRIO_BITS)
51 #define bio_prio(bio)	((bio)->bi_rw >> BIO_PRIO_SHIFT)
52 #define bio_prio_valid(bio)	ioprio_valid(bio_prio(bio))
53 
54 #define bio_set_prio(bio, prio)		do {			\
55 	WARN_ON(prio >= (1 << IOPRIO_BITS));			\
56 	(bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);		\
57 	(bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);	\
58 } while (0)
59 
60 /*
61  * various member access, note that bio_data should of course not be used
62  * on highmem page vectors
63  */
64 #define __bvec_iter_bvec(bvec, iter)	(&(bvec)[(iter).bi_idx])
65 
66 #define bvec_iter_page(bvec, iter)				\
67 	(__bvec_iter_bvec((bvec), (iter))->bv_page)
68 
69 #define bvec_iter_len(bvec, iter)				\
70 	min((iter).bi_size,					\
71 	    __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
72 
73 #define bvec_iter_offset(bvec, iter)				\
74 	(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
75 
76 #define bvec_iter_bvec(bvec, iter)				\
77 ((struct bio_vec) {						\
78 	.bv_page	= bvec_iter_page((bvec), (iter)),	\
79 	.bv_len		= bvec_iter_len((bvec), (iter)),	\
80 	.bv_offset	= bvec_iter_offset((bvec), (iter)),	\
81 })
82 
83 #define bio_iter_iovec(bio, iter)				\
84 	bvec_iter_bvec((bio)->bi_io_vec, (iter))
85 
86 #define bio_iter_page(bio, iter)				\
87 	bvec_iter_page((bio)->bi_io_vec, (iter))
88 #define bio_iter_len(bio, iter)					\
89 	bvec_iter_len((bio)->bi_io_vec, (iter))
90 #define bio_iter_offset(bio, iter)				\
91 	bvec_iter_offset((bio)->bi_io_vec, (iter))
92 
93 #define bio_page(bio)		bio_iter_page((bio), (bio)->bi_iter)
94 #define bio_offset(bio)		bio_iter_offset((bio), (bio)->bi_iter)
95 #define bio_iovec(bio)		bio_iter_iovec((bio), (bio)->bi_iter)
96 
97 #define bio_multiple_segments(bio)				\
98 	((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
99 #define bio_sectors(bio)	((bio)->bi_iter.bi_size >> 9)
100 #define bio_end_sector(bio)	((bio)->bi_iter.bi_sector + bio_sectors((bio)))
101 
102 /*
103  * Check whether this bio carries any data or not. A NULL bio is allowed.
104  */
105 static inline bool bio_has_data(struct bio *bio)
106 {
107 	if (bio &&
108 	    bio->bi_iter.bi_size &&
109 	    !(bio->bi_rw & REQ_DISCARD))
110 		return true;
111 
112 	return false;
113 }
114 
115 static inline bool bio_is_rw(struct bio *bio)
116 {
117 	if (!bio_has_data(bio))
118 		return false;
119 
120 	if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
121 		return false;
122 
123 	return true;
124 }
125 
126 static inline bool bio_mergeable(struct bio *bio)
127 {
128 	if (bio->bi_rw & REQ_NOMERGE_FLAGS)
129 		return false;
130 
131 	return true;
132 }
133 
134 static inline unsigned int bio_cur_bytes(struct bio *bio)
135 {
136 	if (bio_has_data(bio))
137 		return bio_iovec(bio).bv_len;
138 	else /* dataless requests such as discard */
139 		return bio->bi_iter.bi_size;
140 }
141 
142 static inline void *bio_data(struct bio *bio)
143 {
144 	if (bio_has_data(bio))
145 		return page_address(bio_page(bio)) + bio_offset(bio);
146 
147 	return NULL;
148 }
149 
150 /*
151  * will die
152  */
153 #define bio_to_phys(bio)	(page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
154 #define bvec_to_phys(bv)	(page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
155 
156 /*
157  * queues that have highmem support enabled may still need to revert to
158  * PIO transfers occasionally and thus map high pages temporarily. For
159  * permanent PIO fall back, user is probably better off disabling highmem
160  * I/O completely on that queue (see ide-dma for example)
161  */
162 #define __bio_kmap_atomic(bio, iter)				\
163 	(kmap_atomic(bio_iter_iovec((bio), (iter)).bv_page) +	\
164 		bio_iter_iovec((bio), (iter)).bv_offset)
165 
166 #define __bio_kunmap_atomic(addr)	kunmap_atomic(addr)
167 
168 /*
169  * merge helpers etc
170  */
171 
172 /* Default implementation of BIOVEC_PHYS_MERGEABLE */
173 #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
174 	((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
175 
176 /*
177  * allow arch override, for eg virtualized architectures (put in asm/io.h)
178  */
179 #ifndef BIOVEC_PHYS_MERGEABLE
180 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
181 	__BIOVEC_PHYS_MERGEABLE(vec1, vec2)
182 #endif
183 
184 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
185 	(((addr1) | (mask)) == (((addr2) - 1) | (mask)))
186 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
187 	__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
188 
189 /*
190  * Check if adding a bio_vec after bprv with offset would create a gap in
191  * the SG list. Most drivers don't care about this, but some do.
192  */
193 static inline bool bvec_gap_to_prev(struct bio_vec *bprv, unsigned int offset)
194 {
195 	return offset || ((bprv->bv_offset + bprv->bv_len) & (PAGE_SIZE - 1));
196 }
197 
198 #define bio_io_error(bio) bio_endio((bio), -EIO)
199 
200 /*
201  * drivers should _never_ use the all version - the bio may have been split
202  * before it got to the driver and the driver won't own all of it
203  */
204 #define bio_for_each_segment_all(bvl, bio, i)				\
205 	for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
206 
207 static inline void bvec_iter_advance(struct bio_vec *bv, struct bvec_iter *iter,
208 				     unsigned bytes)
209 {
210 	WARN_ONCE(bytes > iter->bi_size,
211 		  "Attempted to advance past end of bvec iter\n");
212 
213 	while (bytes) {
214 		unsigned len = min(bytes, bvec_iter_len(bv, *iter));
215 
216 		bytes -= len;
217 		iter->bi_size -= len;
218 		iter->bi_bvec_done += len;
219 
220 		if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
221 			iter->bi_bvec_done = 0;
222 			iter->bi_idx++;
223 		}
224 	}
225 }
226 
227 #define for_each_bvec(bvl, bio_vec, iter, start)			\
228 	for (iter = (start);						\
229 	     (iter).bi_size &&						\
230 		((bvl = bvec_iter_bvec((bio_vec), (iter))), 1);	\
231 	     bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
232 
233 
234 static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
235 				    unsigned bytes)
236 {
237 	iter->bi_sector += bytes >> 9;
238 
239 	if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
240 		iter->bi_size -= bytes;
241 	else
242 		bvec_iter_advance(bio->bi_io_vec, iter, bytes);
243 }
244 
245 #define __bio_for_each_segment(bvl, bio, iter, start)			\
246 	for (iter = (start);						\
247 	     (iter).bi_size &&						\
248 		((bvl = bio_iter_iovec((bio), (iter))), 1);		\
249 	     bio_advance_iter((bio), &(iter), (bvl).bv_len))
250 
251 #define bio_for_each_segment(bvl, bio, iter)				\
252 	__bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
253 
254 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
255 
256 static inline unsigned bio_segments(struct bio *bio)
257 {
258 	unsigned segs = 0;
259 	struct bio_vec bv;
260 	struct bvec_iter iter;
261 
262 	/*
263 	 * We special case discard/write same, because they interpret bi_size
264 	 * differently:
265 	 */
266 
267 	if (bio->bi_rw & REQ_DISCARD)
268 		return 1;
269 
270 	if (bio->bi_rw & REQ_WRITE_SAME)
271 		return 1;
272 
273 	bio_for_each_segment(bv, bio, iter)
274 		segs++;
275 
276 	return segs;
277 }
278 
279 /*
280  * get a reference to a bio, so it won't disappear. the intended use is
281  * something like:
282  *
283  * bio_get(bio);
284  * submit_bio(rw, bio);
285  * if (bio->bi_flags ...)
286  *	do_something
287  * bio_put(bio);
288  *
289  * without the bio_get(), it could potentially complete I/O before submit_bio
290  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
291  * runs
292  */
293 #define bio_get(bio)	atomic_inc(&(bio)->bi_cnt)
294 
295 enum bip_flags {
296 	BIP_BLOCK_INTEGRITY	= 1 << 0, /* block layer owns integrity data */
297 	BIP_MAPPED_INTEGRITY	= 1 << 1, /* ref tag has been remapped */
298 	BIP_CTRL_NOCHECK	= 1 << 2, /* disable HBA integrity checking */
299 	BIP_DISK_NOCHECK	= 1 << 3, /* disable disk integrity checking */
300 	BIP_IP_CHECKSUM		= 1 << 4, /* IP checksum */
301 };
302 
303 #if defined(CONFIG_BLK_DEV_INTEGRITY)
304 
305 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
306 {
307 	if (bio->bi_rw & REQ_INTEGRITY)
308 		return bio->bi_integrity;
309 
310 	return NULL;
311 }
312 
313 /*
314  * bio integrity payload
315  */
316 struct bio_integrity_payload {
317 	struct bio		*bip_bio;	/* parent bio */
318 
319 	struct bvec_iter	bip_iter;
320 
321 	bio_end_io_t		*bip_end_io;	/* saved I/O completion fn */
322 
323 	unsigned short		bip_slab;	/* slab the bip came from */
324 	unsigned short		bip_vcnt;	/* # of integrity bio_vecs */
325 	unsigned short		bip_max_vcnt;	/* integrity bio_vec slots */
326 	unsigned short		bip_flags;	/* control flags */
327 
328 	struct work_struct	bip_work;	/* I/O completion */
329 
330 	struct bio_vec		*bip_vec;
331 	struct bio_vec		bip_inline_vecs[0];/* embedded bvec array */
332 };
333 
334 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
335 {
336 	struct bio_integrity_payload *bip = bio_integrity(bio);
337 
338 	if (bip)
339 		return bip->bip_flags & flag;
340 
341 	return false;
342 }
343 
344 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
345 {
346 	return bip->bip_iter.bi_sector;
347 }
348 
349 static inline void bip_set_seed(struct bio_integrity_payload *bip,
350 				sector_t seed)
351 {
352 	bip->bip_iter.bi_sector = seed;
353 }
354 
355 #endif /* CONFIG_BLK_DEV_INTEGRITY */
356 
357 extern void bio_trim(struct bio *bio, int offset, int size);
358 extern struct bio *bio_split(struct bio *bio, int sectors,
359 			     gfp_t gfp, struct bio_set *bs);
360 
361 /**
362  * bio_next_split - get next @sectors from a bio, splitting if necessary
363  * @bio:	bio to split
364  * @sectors:	number of sectors to split from the front of @bio
365  * @gfp:	gfp mask
366  * @bs:		bio set to allocate from
367  *
368  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
369  * than @sectors, returns the original bio unchanged.
370  */
371 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
372 					 gfp_t gfp, struct bio_set *bs)
373 {
374 	if (sectors >= bio_sectors(bio))
375 		return bio;
376 
377 	return bio_split(bio, sectors, gfp, bs);
378 }
379 
380 extern struct bio_set *bioset_create(unsigned int, unsigned int);
381 extern struct bio_set *bioset_create_nobvec(unsigned int, unsigned int);
382 extern void bioset_free(struct bio_set *);
383 extern mempool_t *biovec_create_pool(int pool_entries);
384 
385 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
386 extern void bio_put(struct bio *);
387 
388 extern void __bio_clone_fast(struct bio *, struct bio *);
389 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
390 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
391 
392 extern struct bio_set *fs_bio_set;
393 
394 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
395 {
396 	return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
397 }
398 
399 static inline struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
400 {
401 	return bio_clone_bioset(bio, gfp_mask, fs_bio_set);
402 }
403 
404 static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
405 {
406 	return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
407 }
408 
409 static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
410 {
411 	return bio_clone_bioset(bio, gfp_mask, NULL);
412 
413 }
414 
415 extern void bio_endio(struct bio *, int);
416 extern void bio_endio_nodec(struct bio *, int);
417 struct request_queue;
418 extern int bio_phys_segments(struct request_queue *, struct bio *);
419 
420 extern int submit_bio_wait(int rw, struct bio *bio);
421 extern void bio_advance(struct bio *, unsigned);
422 
423 extern void bio_init(struct bio *);
424 extern void bio_reset(struct bio *);
425 void bio_chain(struct bio *, struct bio *);
426 
427 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
428 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
429 			   unsigned int, unsigned int);
430 extern int bio_get_nr_vecs(struct block_device *);
431 struct rq_map_data;
432 extern struct bio *bio_map_user_iov(struct request_queue *,
433 				    const struct iov_iter *, gfp_t);
434 extern void bio_unmap_user(struct bio *);
435 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
436 				gfp_t);
437 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
438 				 gfp_t, int);
439 extern void bio_set_pages_dirty(struct bio *bio);
440 extern void bio_check_pages_dirty(struct bio *bio);
441 
442 void generic_start_io_acct(int rw, unsigned long sectors,
443 			   struct hd_struct *part);
444 void generic_end_io_acct(int rw, 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(struct bio *dst, struct bio *src);
459 extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
460 
461 extern struct bio *bio_copy_user_iov(struct request_queue *,
462 				     struct rq_map_data *,
463 				     const struct iov_iter *,
464 				     gfp_t);
465 extern int bio_uncopy_user(struct bio *);
466 void zero_fill_bio(struct bio *bio);
467 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
468 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
469 extern unsigned int bvec_nr_vecs(unsigned short idx);
470 
471 #ifdef CONFIG_BLK_CGROUP
472 int bio_associate_current(struct bio *bio);
473 void bio_disassociate_task(struct bio *bio);
474 #else	/* CONFIG_BLK_CGROUP */
475 static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
476 static inline void bio_disassociate_task(struct bio *bio) { }
477 #endif	/* CONFIG_BLK_CGROUP */
478 
479 #ifdef CONFIG_HIGHMEM
480 /*
481  * remember never ever reenable interrupts between a bvec_kmap_irq and
482  * bvec_kunmap_irq!
483  */
484 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
485 {
486 	unsigned long addr;
487 
488 	/*
489 	 * might not be a highmem page, but the preempt/irq count
490 	 * balancing is a lot nicer this way
491 	 */
492 	local_irq_save(*flags);
493 	addr = (unsigned long) kmap_atomic(bvec->bv_page);
494 
495 	BUG_ON(addr & ~PAGE_MASK);
496 
497 	return (char *) addr + bvec->bv_offset;
498 }
499 
500 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
501 {
502 	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
503 
504 	kunmap_atomic((void *) ptr);
505 	local_irq_restore(*flags);
506 }
507 
508 #else
509 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
510 {
511 	return page_address(bvec->bv_page) + bvec->bv_offset;
512 }
513 
514 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
515 {
516 	*flags = 0;
517 }
518 #endif
519 
520 static inline char *__bio_kmap_irq(struct bio *bio, struct bvec_iter iter,
521 				   unsigned long *flags)
522 {
523 	return bvec_kmap_irq(&bio_iter_iovec(bio, iter), flags);
524 }
525 #define __bio_kunmap_irq(buf, flags)	bvec_kunmap_irq(buf, flags)
526 
527 #define bio_kmap_irq(bio, flags) \
528 	__bio_kmap_irq((bio), (bio)->bi_iter, (flags))
529 #define bio_kunmap_irq(buf,flags)	__bio_kunmap_irq(buf, flags)
530 
531 /*
532  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
533  *
534  * A bio_list anchors a singly-linked list of bios chained through the bi_next
535  * member of the bio.  The bio_list also caches the last list member to allow
536  * fast access to the tail.
537  */
538 struct bio_list {
539 	struct bio *head;
540 	struct bio *tail;
541 };
542 
543 static inline int bio_list_empty(const struct bio_list *bl)
544 {
545 	return bl->head == NULL;
546 }
547 
548 static inline void bio_list_init(struct bio_list *bl)
549 {
550 	bl->head = bl->tail = NULL;
551 }
552 
553 #define BIO_EMPTY_LIST	{ NULL, NULL }
554 
555 #define bio_list_for_each(bio, bl) \
556 	for (bio = (bl)->head; bio; bio = bio->bi_next)
557 
558 static inline unsigned bio_list_size(const struct bio_list *bl)
559 {
560 	unsigned sz = 0;
561 	struct bio *bio;
562 
563 	bio_list_for_each(bio, bl)
564 		sz++;
565 
566 	return sz;
567 }
568 
569 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
570 {
571 	bio->bi_next = NULL;
572 
573 	if (bl->tail)
574 		bl->tail->bi_next = bio;
575 	else
576 		bl->head = bio;
577 
578 	bl->tail = bio;
579 }
580 
581 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
582 {
583 	bio->bi_next = bl->head;
584 
585 	bl->head = bio;
586 
587 	if (!bl->tail)
588 		bl->tail = bio;
589 }
590 
591 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
592 {
593 	if (!bl2->head)
594 		return;
595 
596 	if (bl->tail)
597 		bl->tail->bi_next = bl2->head;
598 	else
599 		bl->head = bl2->head;
600 
601 	bl->tail = bl2->tail;
602 }
603 
604 static inline void bio_list_merge_head(struct bio_list *bl,
605 				       struct bio_list *bl2)
606 {
607 	if (!bl2->head)
608 		return;
609 
610 	if (bl->head)
611 		bl2->tail->bi_next = bl->head;
612 	else
613 		bl->tail = bl2->tail;
614 
615 	bl->head = bl2->head;
616 }
617 
618 static inline struct bio *bio_list_peek(struct bio_list *bl)
619 {
620 	return bl->head;
621 }
622 
623 static inline struct bio *bio_list_pop(struct bio_list *bl)
624 {
625 	struct bio *bio = bl->head;
626 
627 	if (bio) {
628 		bl->head = bl->head->bi_next;
629 		if (!bl->head)
630 			bl->tail = NULL;
631 
632 		bio->bi_next = NULL;
633 	}
634 
635 	return bio;
636 }
637 
638 static inline struct bio *bio_list_get(struct bio_list *bl)
639 {
640 	struct bio *bio = bl->head;
641 
642 	bl->head = bl->tail = NULL;
643 
644 	return bio;
645 }
646 
647 /*
648  * bio_set is used to allow other portions of the IO system to
649  * allocate their own private memory pools for bio and iovec structures.
650  * These memory pools in turn all allocate from the bio_slab
651  * and the bvec_slabs[].
652  */
653 #define BIO_POOL_SIZE 2
654 #define BIOVEC_NR_POOLS 6
655 #define BIOVEC_MAX_IDX	(BIOVEC_NR_POOLS - 1)
656 
657 struct bio_set {
658 	struct kmem_cache *bio_slab;
659 	unsigned int front_pad;
660 
661 	mempool_t *bio_pool;
662 	mempool_t *bvec_pool;
663 #if defined(CONFIG_BLK_DEV_INTEGRITY)
664 	mempool_t *bio_integrity_pool;
665 	mempool_t *bvec_integrity_pool;
666 #endif
667 
668 	/*
669 	 * Deadlock avoidance for stacking block drivers: see comments in
670 	 * bio_alloc_bioset() for details
671 	 */
672 	spinlock_t		rescue_lock;
673 	struct bio_list		rescue_list;
674 	struct work_struct	rescue_work;
675 	struct workqueue_struct	*rescue_workqueue;
676 };
677 
678 struct biovec_slab {
679 	int nr_vecs;
680 	char *name;
681 	struct kmem_cache *slab;
682 };
683 
684 /*
685  * a small number of entries is fine, not going to be performance critical.
686  * basically we just need to survive
687  */
688 #define BIO_SPLIT_ENTRIES 2
689 
690 #if defined(CONFIG_BLK_DEV_INTEGRITY)
691 
692 #define bip_for_each_vec(bvl, bip, iter)				\
693 	for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
694 
695 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)			\
696 	for_each_bio(_bio)						\
697 		bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
698 
699 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
700 extern void bio_integrity_free(struct bio *);
701 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
702 extern bool bio_integrity_enabled(struct bio *bio);
703 extern int bio_integrity_prep(struct bio *);
704 extern void bio_integrity_endio(struct bio *, int);
705 extern void bio_integrity_advance(struct bio *, unsigned int);
706 extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
707 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
708 extern int bioset_integrity_create(struct bio_set *, int);
709 extern void bioset_integrity_free(struct bio_set *);
710 extern void bio_integrity_init(void);
711 
712 #else /* CONFIG_BLK_DEV_INTEGRITY */
713 
714 static inline void *bio_integrity(struct bio *bio)
715 {
716 	return NULL;
717 }
718 
719 static inline bool bio_integrity_enabled(struct bio *bio)
720 {
721 	return false;
722 }
723 
724 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
725 {
726 	return 0;
727 }
728 
729 static inline void bioset_integrity_free (struct bio_set *bs)
730 {
731 	return;
732 }
733 
734 static inline int bio_integrity_prep(struct bio *bio)
735 {
736 	return 0;
737 }
738 
739 static inline void bio_integrity_free(struct bio *bio)
740 {
741 	return;
742 }
743 
744 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
745 				      gfp_t gfp_mask)
746 {
747 	return 0;
748 }
749 
750 static inline void bio_integrity_advance(struct bio *bio,
751 					 unsigned int bytes_done)
752 {
753 	return;
754 }
755 
756 static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
757 				      unsigned int sectors)
758 {
759 	return;
760 }
761 
762 static inline void bio_integrity_init(void)
763 {
764 	return;
765 }
766 
767 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
768 {
769 	return false;
770 }
771 
772 #endif /* CONFIG_BLK_DEV_INTEGRITY */
773 
774 #endif /* CONFIG_BLOCK */
775 #endif /* __LINUX_BIO_H */
776