xref: /linux/include/linux/bio.h (revision 7ca44303f9f6160a2f87ae3d5d2326d9127cd61c)
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/mempool.h>
9 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
10 #include <linux/blk_types.h>
11 #include <linux/uio.h>
12 
13 #define BIO_MAX_VECS		256U
14 #define BIO_MAX_INLINE_VECS	UIO_MAXIOV
15 
16 struct queue_limits;
17 
18 static inline unsigned int bio_max_segs(unsigned int nr_segs)
19 {
20 	return min(nr_segs, BIO_MAX_VECS);
21 }
22 
23 #define bio_iter_iovec(bio, iter)				\
24 	bvec_iter_bvec((bio)->bi_io_vec, (iter))
25 
26 #define bio_iter_page(bio, iter)				\
27 	bvec_iter_page((bio)->bi_io_vec, (iter))
28 #define bio_iter_len(bio, iter)					\
29 	bvec_iter_len((bio)->bi_io_vec, (iter))
30 #define bio_iter_offset(bio, iter)				\
31 	bvec_iter_offset((bio)->bi_io_vec, (iter))
32 
33 #define bio_page(bio)		bio_iter_page((bio), (bio)->bi_iter)
34 #define bio_offset(bio)		bio_iter_offset((bio), (bio)->bi_iter)
35 #define bio_iovec(bio)		bio_iter_iovec((bio), (bio)->bi_iter)
36 
37 #define bvec_iter_sectors(iter)	((iter).bi_size >> 9)
38 #define bvec_iter_end_sector(iter) ((iter).bi_sector + bvec_iter_sectors((iter)))
39 
40 #define bio_sectors(bio)	bvec_iter_sectors((bio)->bi_iter)
41 #define bio_end_sector(bio)	bvec_iter_end_sector((bio)->bi_iter)
42 
43 /*
44  * Return the data direction, READ or WRITE.
45  */
46 #define bio_data_dir(bio) \
47 	(op_is_write(bio_op(bio)) ? WRITE : READ)
48 
49 static inline bool bio_flagged(const struct bio *bio, unsigned int bit)
50 {
51 	return bio->bi_flags & (1U << bit);
52 }
53 
54 static inline void bio_set_flag(struct bio *bio, unsigned int bit)
55 {
56 	bio->bi_flags |= (1U << bit);
57 }
58 
59 static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
60 {
61 	bio->bi_flags &= ~(1U << bit);
62 }
63 
64 /*
65  * Check whether this bio carries any data or not. A NULL bio is allowed.
66  */
67 static inline bool bio_has_data(struct bio *bio)
68 {
69 	if (bio &&
70 	    bio->bi_iter.bi_size &&
71 	    bio_op(bio) != REQ_OP_DISCARD &&
72 	    bio_op(bio) != REQ_OP_SECURE_ERASE &&
73 	    bio_op(bio) != REQ_OP_WRITE_ZEROES)
74 		return true;
75 
76 	return false;
77 }
78 
79 static inline bool bio_no_advance_iter(const struct bio *bio)
80 {
81 	return bio_op(bio) == REQ_OP_DISCARD ||
82 	       bio_op(bio) == REQ_OP_SECURE_ERASE ||
83 	       bio_op(bio) == REQ_OP_WRITE_ZEROES;
84 }
85 
86 static inline void *bio_data(struct bio *bio)
87 {
88 	if (bio_has_data(bio))
89 		return page_address(bio_page(bio)) + bio_offset(bio);
90 
91 	return NULL;
92 }
93 
94 static inline bool bio_next_segment(const struct bio *bio,
95 				    struct bvec_iter_all *iter)
96 {
97 	if (iter->idx >= bio->bi_vcnt)
98 		return false;
99 
100 	bvec_advance(&bio->bi_io_vec[iter->idx], iter);
101 	return true;
102 }
103 
104 /*
105  * drivers should _never_ use the all version - the bio may have been split
106  * before it got to the driver and the driver won't own all of it
107  */
108 #define bio_for_each_segment_all(bvl, bio, iter) \
109 	for (bvl = bvec_init_iter_all(&iter); bio_next_segment((bio), &iter); )
110 
111 static inline void bio_advance_iter(const struct bio *bio,
112 				    struct bvec_iter *iter, unsigned int bytes)
113 {
114 	iter->bi_sector += bytes >> 9;
115 
116 	if (bio_no_advance_iter(bio))
117 		iter->bi_size -= bytes;
118 	else
119 		bvec_iter_advance(bio->bi_io_vec, iter, bytes);
120 		/* TODO: It is reasonable to complete bio with error here. */
121 }
122 
123 /* @bytes should be less or equal to bvec[i->bi_idx].bv_len */
124 static inline void bio_advance_iter_single(const struct bio *bio,
125 					   struct bvec_iter *iter,
126 					   unsigned int bytes)
127 {
128 	iter->bi_sector += bytes >> 9;
129 
130 	if (bio_no_advance_iter(bio))
131 		iter->bi_size -= bytes;
132 	else
133 		bvec_iter_advance_single(bio->bi_io_vec, iter, bytes);
134 }
135 
136 void __bio_advance(struct bio *, unsigned bytes);
137 
138 /**
139  * bio_advance - increment/complete a bio by some number of bytes
140  * @bio:	bio to advance
141  * @nbytes:	number of bytes to complete
142  *
143  * This updates bi_sector, bi_size and bi_idx; if the number of bytes to
144  * complete doesn't align with a bvec boundary, then bv_len and bv_offset will
145  * be updated on the last bvec as well.
146  *
147  * @bio will then represent the remaining, uncompleted portion of the io.
148  */
149 static inline void bio_advance(struct bio *bio, unsigned int nbytes)
150 {
151 	if (nbytes == bio->bi_iter.bi_size) {
152 		bio->bi_iter.bi_size = 0;
153 		return;
154 	}
155 	__bio_advance(bio, nbytes);
156 }
157 
158 #define __bio_for_each_segment(bvl, bio, iter, start)			\
159 	for (iter = (start);						\
160 	     (iter).bi_size &&						\
161 		((bvl = bio_iter_iovec((bio), (iter))), 1);		\
162 	     bio_advance_iter_single((bio), &(iter), (bvl).bv_len))
163 
164 #define bio_for_each_segment(bvl, bio, iter)				\
165 	__bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
166 
167 #define __bio_for_each_bvec(bvl, bio, iter, start)		\
168 	for (iter = (start);						\
169 	     (iter).bi_size &&						\
170 		((bvl = mp_bvec_iter_bvec((bio)->bi_io_vec, (iter))), 1); \
171 	     bio_advance_iter_single((bio), &(iter), (bvl).bv_len))
172 
173 /* iterate over multi-page bvec */
174 #define bio_for_each_bvec(bvl, bio, iter)			\
175 	__bio_for_each_bvec(bvl, bio, iter, (bio)->bi_iter)
176 
177 /*
178  * Iterate over all multi-page bvecs. Drivers shouldn't use this version for the
179  * same reasons as bio_for_each_segment_all().
180  */
181 #define bio_for_each_bvec_all(bvl, bio, i)		\
182 	for (i = 0, bvl = bio_first_bvec_all(bio);	\
183 	     i < (bio)->bi_vcnt; i++, bvl++)
184 
185 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
186 
187 static inline unsigned bio_segments(struct bio *bio)
188 {
189 	unsigned segs = 0;
190 	struct bio_vec bv;
191 	struct bvec_iter iter;
192 
193 	/*
194 	 * We special case discard/write same/write zeroes, because they
195 	 * interpret bi_size differently:
196 	 */
197 
198 	switch (bio_op(bio)) {
199 	case REQ_OP_DISCARD:
200 	case REQ_OP_SECURE_ERASE:
201 	case REQ_OP_WRITE_ZEROES:
202 		return 0;
203 	default:
204 		break;
205 	}
206 
207 	bio_for_each_segment(bv, bio, iter)
208 		segs++;
209 
210 	return segs;
211 }
212 
213 /*
214  * get a reference to a bio, so it won't disappear. the intended use is
215  * something like:
216  *
217  * bio_get(bio);
218  * submit_bio(rw, bio);
219  * if (bio->bi_flags ...)
220  *	do_something
221  * bio_put(bio);
222  *
223  * without the bio_get(), it could potentially complete I/O before submit_bio
224  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
225  * runs
226  */
227 static inline void bio_get(struct bio *bio)
228 {
229 	bio->bi_flags |= (1 << BIO_REFFED);
230 	smp_mb__before_atomic();
231 	atomic_inc(&bio->__bi_cnt);
232 }
233 
234 static inline void bio_cnt_set(struct bio *bio, unsigned int count)
235 {
236 	if (count != 1) {
237 		bio->bi_flags |= (1 << BIO_REFFED);
238 		smp_mb();
239 	}
240 	atomic_set(&bio->__bi_cnt, count);
241 }
242 
243 static inline struct bio_vec *bio_first_bvec_all(struct bio *bio)
244 {
245 	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
246 	return bio->bi_io_vec;
247 }
248 
249 static inline struct page *bio_first_page_all(struct bio *bio)
250 {
251 	return bio_first_bvec_all(bio)->bv_page;
252 }
253 
254 static inline struct folio *bio_first_folio_all(struct bio *bio)
255 {
256 	return page_folio(bio_first_page_all(bio));
257 }
258 
259 static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
260 {
261 	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
262 	return &bio->bi_io_vec[bio->bi_vcnt - 1];
263 }
264 
265 /**
266  * struct folio_iter - State for iterating all folios in a bio.
267  * @folio: The current folio we're iterating.  NULL after the last folio.
268  * @offset: The byte offset within the current folio.
269  * @length: The number of bytes in this iteration (will not cross folio
270  *	boundary).
271  */
272 struct folio_iter {
273 	struct folio *folio;
274 	size_t offset;
275 	size_t length;
276 	/* private: for use by the iterator */
277 	struct folio *_next;
278 	size_t _seg_count;
279 	int _i;
280 };
281 
282 static inline void bio_first_folio(struct folio_iter *fi, struct bio *bio,
283 				   int i)
284 {
285 	struct bio_vec *bvec = bio_first_bvec_all(bio) + i;
286 
287 	if (unlikely(i >= bio->bi_vcnt)) {
288 		fi->folio = NULL;
289 		return;
290 	}
291 
292 	fi->folio = page_folio(bvec->bv_page);
293 	fi->offset = bvec->bv_offset +
294 			PAGE_SIZE * folio_page_idx(fi->folio, bvec->bv_page);
295 	fi->_seg_count = bvec->bv_len;
296 	fi->length = min(folio_size(fi->folio) - fi->offset, fi->_seg_count);
297 	fi->_next = folio_next(fi->folio);
298 	fi->_i = i;
299 }
300 
301 static inline void bio_next_folio(struct folio_iter *fi, struct bio *bio)
302 {
303 	fi->_seg_count -= fi->length;
304 	if (fi->_seg_count) {
305 		fi->folio = fi->_next;
306 		fi->offset = 0;
307 		fi->length = min(folio_size(fi->folio), fi->_seg_count);
308 		fi->_next = folio_next(fi->folio);
309 	} else {
310 		bio_first_folio(fi, bio, fi->_i + 1);
311 	}
312 }
313 
314 /**
315  * bio_for_each_folio_all - Iterate over each folio in a bio.
316  * @fi: struct folio_iter which is updated for each folio.
317  * @bio: struct bio to iterate over.
318  */
319 #define bio_for_each_folio_all(fi, bio)				\
320 	for (bio_first_folio(&fi, bio, 0); fi.folio; bio_next_folio(&fi, bio))
321 
322 void bio_trim(struct bio *bio, sector_t offset, sector_t size);
323 extern struct bio *bio_split(struct bio *bio, int sectors,
324 			     gfp_t gfp, struct bio_set *bs);
325 int bio_split_io_at(struct bio *bio, const struct queue_limits *lim,
326 		unsigned *segs, unsigned max_bytes, unsigned len_align);
327 u8 bio_seg_gap(struct request_queue *q, struct bio *prev, struct bio *next,
328 		u8 gaps_bit);
329 
330 /**
331  * bio_next_split - get next @sectors from a bio, splitting if necessary
332  * @bio:	bio to split
333  * @sectors:	number of sectors to split from the front of @bio
334  * @gfp:	gfp mask
335  * @bs:		bio set to allocate from
336  *
337  * Return: a bio representing the next @sectors of @bio - if the bio is smaller
338  * than @sectors, returns the original bio unchanged.
339  */
340 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
341 					 gfp_t gfp, struct bio_set *bs)
342 {
343 	if (sectors >= bio_sectors(bio))
344 		return bio;
345 
346 	return bio_split(bio, sectors, gfp, bs);
347 }
348 
349 enum {
350 	BIOSET_NEED_BVECS = BIT(0),
351 	BIOSET_NEED_RESCUER = BIT(1),
352 	BIOSET_PERCPU_CACHE = BIT(2),
353 };
354 extern int bioset_init(struct bio_set *, unsigned int, unsigned int, int flags);
355 extern void bioset_exit(struct bio_set *);
356 extern int biovec_init_pool(mempool_t *pool, int pool_entries);
357 
358 struct bio *bio_alloc_bioset(struct block_device *bdev, unsigned short nr_vecs,
359 			     blk_opf_t opf, gfp_t gfp_mask,
360 			     struct bio_set *bs);
361 struct bio *bio_kmalloc(unsigned short nr_vecs, gfp_t gfp_mask);
362 extern void bio_put(struct bio *);
363 
364 struct bio *bio_alloc_clone(struct block_device *bdev, struct bio *bio_src,
365 		gfp_t gfp, struct bio_set *bs);
366 int bio_init_clone(struct block_device *bdev, struct bio *bio,
367 		struct bio *bio_src, gfp_t gfp);
368 
369 extern struct bio_set fs_bio_set;
370 
371 static inline struct bio *bio_alloc(struct block_device *bdev,
372 		unsigned short nr_vecs, blk_opf_t opf, gfp_t gfp_mask)
373 {
374 	return bio_alloc_bioset(bdev, nr_vecs, opf, gfp_mask, &fs_bio_set);
375 }
376 
377 void submit_bio(struct bio *bio);
378 
379 extern void bio_endio(struct bio *);
380 
381 static inline void bio_io_error(struct bio *bio)
382 {
383 	bio->bi_status = BLK_STS_IOERR;
384 	bio_endio(bio);
385 }
386 
387 static inline void bio_wouldblock_error(struct bio *bio)
388 {
389 	bio_set_flag(bio, BIO_QUIET);
390 	bio->bi_status = BLK_STS_AGAIN;
391 	bio_endio(bio);
392 }
393 
394 /*
395  * Calculate number of bvec segments that should be allocated to fit data
396  * pointed by @iter. If @iter is backed by bvec it's going to be reused
397  * instead of allocating a new one.
398  */
399 static inline int bio_iov_vecs_to_alloc(struct iov_iter *iter, int max_segs)
400 {
401 	if (iov_iter_is_bvec(iter))
402 		return 0;
403 	return iov_iter_npages(iter, max_segs);
404 }
405 
406 struct request_queue;
407 
408 void bio_init(struct bio *bio, struct block_device *bdev, struct bio_vec *table,
409 	      unsigned short max_vecs, blk_opf_t opf);
410 static inline void bio_init_inline(struct bio *bio, struct block_device *bdev,
411 	      unsigned short max_vecs, blk_opf_t opf)
412 {
413 	bio_init(bio, bdev, bio_inline_vecs(bio), max_vecs, opf);
414 }
415 extern void bio_uninit(struct bio *);
416 void bio_reset(struct bio *bio, struct block_device *bdev, blk_opf_t opf);
417 void bio_reuse(struct bio *bio, blk_opf_t opf);
418 void bio_chain(struct bio *, struct bio *);
419 
420 int __must_check bio_add_page(struct bio *bio, struct page *page, unsigned len,
421 			      unsigned off);
422 bool __must_check bio_add_folio(struct bio *bio, struct folio *folio,
423 				size_t len, size_t off);
424 void __bio_add_page(struct bio *bio, struct page *page,
425 		unsigned int len, unsigned int off);
426 void bio_add_folio_nofail(struct bio *bio, struct folio *folio, size_t len,
427 			  size_t off);
428 void bio_add_virt_nofail(struct bio *bio, void *vaddr, unsigned len);
429 
430 /**
431  * bio_add_max_vecs - number of bio_vecs needed to add data to a bio
432  * @kaddr: kernel virtual address to add
433  * @len: length in bytes to add
434  *
435  * Calculate how many bio_vecs need to be allocated to add the kernel virtual
436  * address range in [@kaddr:@len] in the worse case.
437  */
438 static inline unsigned int bio_add_max_vecs(void *kaddr, unsigned int len)
439 {
440 	if (is_vmalloc_addr(kaddr))
441 		return DIV_ROUND_UP(offset_in_page(kaddr) + len, PAGE_SIZE);
442 	return 1;
443 }
444 
445 unsigned int bio_add_vmalloc_chunk(struct bio *bio, void *vaddr, unsigned len);
446 bool bio_add_vmalloc(struct bio *bio, void *vaddr, unsigned int len);
447 
448 int submit_bio_wait(struct bio *bio);
449 int bdev_rw_virt(struct block_device *bdev, sector_t sector, void *data,
450 		size_t len, enum req_op op);
451 
452 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter,
453 		unsigned len_align_mask);
454 
455 void bio_iov_bvec_set(struct bio *bio, const struct iov_iter *iter);
456 void __bio_release_pages(struct bio *bio, bool mark_dirty);
457 extern void bio_set_pages_dirty(struct bio *bio);
458 extern void bio_check_pages_dirty(struct bio *bio);
459 
460 extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
461 			       struct bio *src, struct bvec_iter *src_iter);
462 extern void bio_copy_data(struct bio *dst, struct bio *src);
463 extern void bio_free_pages(struct bio *bio);
464 void guard_bio_eod(struct bio *bio);
465 void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter);
466 
467 static inline void zero_fill_bio(struct bio *bio)
468 {
469 	zero_fill_bio_iter(bio, bio->bi_iter);
470 }
471 
472 static inline void bio_release_pages(struct bio *bio, bool mark_dirty)
473 {
474 	if (bio_flagged(bio, BIO_PAGE_PINNED))
475 		__bio_release_pages(bio, mark_dirty);
476 }
477 
478 #define bio_dev(bio) \
479 	disk_devt((bio)->bi_bdev->bd_disk)
480 
481 #ifdef CONFIG_BLK_CGROUP
482 void bio_associate_blkg(struct bio *bio);
483 void bio_associate_blkg_from_css(struct bio *bio,
484 				 struct cgroup_subsys_state *css);
485 void bio_clone_blkg_association(struct bio *dst, struct bio *src);
486 void blkcg_punt_bio_submit(struct bio *bio);
487 #else	/* CONFIG_BLK_CGROUP */
488 static inline void bio_associate_blkg(struct bio *bio) { }
489 static inline void bio_associate_blkg_from_css(struct bio *bio,
490 					       struct cgroup_subsys_state *css)
491 { }
492 static inline void bio_clone_blkg_association(struct bio *dst,
493 					      struct bio *src) { }
494 static inline void blkcg_punt_bio_submit(struct bio *bio)
495 {
496 	submit_bio(bio);
497 }
498 #endif	/* CONFIG_BLK_CGROUP */
499 
500 static inline void bio_set_dev(struct bio *bio, struct block_device *bdev)
501 {
502 	bio_clear_flag(bio, BIO_REMAPPED);
503 	if (bio->bi_bdev != bdev)
504 		bio_clear_flag(bio, BIO_BPS_THROTTLED);
505 	bio->bi_bdev = bdev;
506 	bio_associate_blkg(bio);
507 }
508 
509 /*
510  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
511  *
512  * A bio_list anchors a singly-linked list of bios chained through the bi_next
513  * member of the bio.  The bio_list also caches the last list member to allow
514  * fast access to the tail.
515  */
516 struct bio_list {
517 	struct bio *head;
518 	struct bio *tail;
519 };
520 
521 static inline int bio_list_empty(const struct bio_list *bl)
522 {
523 	return bl->head == NULL;
524 }
525 
526 static inline void bio_list_init(struct bio_list *bl)
527 {
528 	bl->head = bl->tail = NULL;
529 }
530 
531 #define BIO_EMPTY_LIST	{ NULL, NULL }
532 
533 #define bio_list_for_each(bio, bl) \
534 	for (bio = (bl)->head; bio; bio = bio->bi_next)
535 
536 static inline unsigned bio_list_size(const struct bio_list *bl)
537 {
538 	unsigned sz = 0;
539 	struct bio *bio;
540 
541 	bio_list_for_each(bio, bl)
542 		sz++;
543 
544 	return sz;
545 }
546 
547 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
548 {
549 	bio->bi_next = NULL;
550 
551 	if (bl->tail)
552 		bl->tail->bi_next = bio;
553 	else
554 		bl->head = bio;
555 
556 	bl->tail = bio;
557 }
558 
559 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
560 {
561 	bio->bi_next = bl->head;
562 
563 	bl->head = bio;
564 
565 	if (!bl->tail)
566 		bl->tail = bio;
567 }
568 
569 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
570 {
571 	if (!bl2->head)
572 		return;
573 
574 	if (bl->tail)
575 		bl->tail->bi_next = bl2->head;
576 	else
577 		bl->head = bl2->head;
578 
579 	bl->tail = bl2->tail;
580 }
581 
582 static inline void bio_list_merge_init(struct bio_list *bl,
583 		struct bio_list *bl2)
584 {
585 	bio_list_merge(bl, bl2);
586 	bio_list_init(bl2);
587 }
588 
589 static inline void bio_list_merge_head(struct bio_list *bl,
590 				       struct bio_list *bl2)
591 {
592 	if (!bl2->head)
593 		return;
594 
595 	if (bl->head)
596 		bl2->tail->bi_next = bl->head;
597 	else
598 		bl->tail = bl2->tail;
599 
600 	bl->head = bl2->head;
601 }
602 
603 static inline struct bio *bio_list_peek(struct bio_list *bl)
604 {
605 	return bl->head;
606 }
607 
608 static inline struct bio *bio_list_pop(struct bio_list *bl)
609 {
610 	struct bio *bio = bl->head;
611 
612 	if (bio) {
613 		bl->head = bl->head->bi_next;
614 		if (!bl->head)
615 			bl->tail = NULL;
616 
617 		bio->bi_next = NULL;
618 	}
619 
620 	return bio;
621 }
622 
623 static inline struct bio *bio_list_get(struct bio_list *bl)
624 {
625 	struct bio *bio = bl->head;
626 
627 	bl->head = bl->tail = NULL;
628 
629 	return bio;
630 }
631 
632 /*
633  * Increment chain count for the bio. Make sure the CHAIN flag update
634  * is visible before the raised count.
635  */
636 static inline void bio_inc_remaining(struct bio *bio)
637 {
638 	bio_set_flag(bio, BIO_CHAIN);
639 	smp_mb__before_atomic();
640 	atomic_inc(&bio->__bi_remaining);
641 }
642 
643 /*
644  * bio_set is used to allow other portions of the IO system to
645  * allocate their own private memory pools for bio and iovec structures.
646  * These memory pools in turn all allocate from the bio_slab
647  * and the bvec_slabs[].
648  */
649 #define BIO_POOL_SIZE 2
650 
651 struct bio_set {
652 	struct kmem_cache *bio_slab;
653 	unsigned int front_pad;
654 
655 	/*
656 	 * per-cpu bio alloc cache
657 	 */
658 	struct bio_alloc_cache __percpu *cache;
659 
660 	mempool_t bio_pool;
661 	mempool_t bvec_pool;
662 
663 	unsigned int back_pad;
664 	/*
665 	 * Deadlock avoidance for stacking block drivers: see comments in
666 	 * bio_alloc_bioset() for details
667 	 */
668 	spinlock_t		rescue_lock;
669 	struct bio_list		rescue_list;
670 	struct work_struct	rescue_work;
671 	struct workqueue_struct	*rescue_workqueue;
672 
673 	/*
674 	 * Hot un-plug notifier for the per-cpu cache, if used
675 	 */
676 	struct hlist_node cpuhp_dead;
677 };
678 
679 static inline bool bioset_initialized(struct bio_set *bs)
680 {
681 	return bs->bio_slab != NULL;
682 }
683 
684 /*
685  * Mark a bio as polled. Note that for async polled IO, the caller must
686  * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
687  * We cannot block waiting for requests on polled IO, as those completions
688  * must be found by the caller. This is different than IRQ driven IO, where
689  * it's safe to wait for IO to complete.
690  */
691 static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
692 {
693 	bio->bi_opf |= REQ_POLLED;
694 	if (kiocb->ki_flags & IOCB_NOWAIT)
695 		bio->bi_opf |= REQ_NOWAIT;
696 }
697 
698 static inline void bio_clear_polled(struct bio *bio)
699 {
700 	bio->bi_opf &= ~REQ_POLLED;
701 }
702 
703 /**
704  * bio_is_zone_append - is this a zone append bio?
705  * @bio:	bio to check
706  *
707  * Check if @bio is a zone append operation.  Core block layer code and end_io
708  * handlers must use this instead of an open coded REQ_OP_ZONE_APPEND check
709  * because the block layer can rewrite REQ_OP_ZONE_APPEND to REQ_OP_WRITE if
710  * it is not natively supported.
711  */
712 static inline bool bio_is_zone_append(struct bio *bio)
713 {
714 	if (!IS_ENABLED(CONFIG_BLK_DEV_ZONED))
715 		return false;
716 	return bio_op(bio) == REQ_OP_ZONE_APPEND ||
717 		bio_flagged(bio, BIO_EMULATES_ZONE_APPEND);
718 }
719 
720 struct bio *blk_next_bio(struct bio *bio, struct block_device *bdev,
721 		unsigned int nr_pages, blk_opf_t opf, gfp_t gfp);
722 struct bio *bio_chain_and_submit(struct bio *prev, struct bio *new);
723 
724 struct bio *blk_alloc_discard_bio(struct block_device *bdev,
725 		sector_t *sector, sector_t *nr_sects, gfp_t gfp_mask);
726 
727 #endif /* __LINUX_BIO_H */
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