1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
8 #include <linux/highmem.h>
9 #include <linux/mempool.h>
10 #include <linux/ioprio.h>
11 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
12 #include <linux/blk_types.h>
17 #define BIO_BUG_ON BUG_ON
22 #define BIO_MAX_PAGES 256
24 #define bio_prio(bio) (bio)->bi_ioprio
25 #define bio_set_prio(bio, prio) ((bio)->bi_ioprio = prio)
27 #define bio_iter_iovec(bio, iter) \
28 bvec_iter_bvec((bio)->bi_io_vec, (iter))
30 #define bio_iter_page(bio, iter) \
31 bvec_iter_page((bio)->bi_io_vec, (iter))
32 #define bio_iter_len(bio, iter) \
33 bvec_iter_len((bio)->bi_io_vec, (iter))
34 #define bio_iter_offset(bio, iter) \
35 bvec_iter_offset((bio)->bi_io_vec, (iter))
37 #define bio_page(bio) bio_iter_page((bio), (bio)->bi_iter)
38 #define bio_offset(bio) bio_iter_offset((bio), (bio)->bi_iter)
39 #define bio_iovec(bio) bio_iter_iovec((bio), (bio)->bi_iter)
41 #define bio_multiple_segments(bio) \
42 ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
44 #define bvec_iter_sectors(iter) ((iter).bi_size >> 9)
45 #define bvec_iter_end_sector(iter) ((iter).bi_sector + bvec_iter_sectors((iter)))
47 #define bio_sectors(bio) bvec_iter_sectors((bio)->bi_iter)
48 #define bio_end_sector(bio) bvec_iter_end_sector((bio)->bi_iter)
51 * Return the data direction, READ or WRITE.
53 #define bio_data_dir(bio) \
54 (op_is_write(bio_op(bio)) ? WRITE : READ)
57 * Check whether this bio carries any data or not. A NULL bio is allowed.
59 static inline bool bio_has_data(struct bio
*bio
)
62 bio
->bi_iter
.bi_size
&&
63 bio_op(bio
) != REQ_OP_DISCARD
&&
64 bio_op(bio
) != REQ_OP_SECURE_ERASE
&&
65 bio_op(bio
) != REQ_OP_WRITE_ZEROES
)
71 static inline bool bio_no_advance_iter(const struct bio
*bio
)
73 return bio_op(bio
) == REQ_OP_DISCARD
||
74 bio_op(bio
) == REQ_OP_SECURE_ERASE
||
75 bio_op(bio
) == REQ_OP_WRITE_SAME
||
76 bio_op(bio
) == REQ_OP_WRITE_ZEROES
;
79 static inline bool bio_mergeable(struct bio
*bio
)
81 if (bio
->bi_opf
& REQ_NOMERGE_FLAGS
)
87 static inline unsigned int bio_cur_bytes(struct bio
*bio
)
89 if (bio_has_data(bio
))
90 return bio_iovec(bio
).bv_len
;
91 else /* dataless requests such as discard */
92 return bio
->bi_iter
.bi_size
;
95 static inline void *bio_data(struct bio
*bio
)
97 if (bio_has_data(bio
))
98 return page_address(bio_page(bio
)) + bio_offset(bio
);
104 * bio_full - check if the bio is full
106 * @len: length of one segment to be added
108 * Return true if @bio is full and one segment with @len bytes can't be
109 * added to the bio, otherwise return false
111 static inline bool bio_full(struct bio
*bio
, unsigned len
)
113 if (bio
->bi_vcnt
>= bio
->bi_max_vecs
)
116 if (bio
->bi_iter
.bi_size
> UINT_MAX
- len
)
122 static inline bool bio_next_segment(const struct bio
*bio
,
123 struct bvec_iter_all
*iter
)
125 if (iter
->idx
>= bio
->bi_vcnt
)
128 bvec_advance(&bio
->bi_io_vec
[iter
->idx
], iter
);
133 * drivers should _never_ use the all version - the bio may have been split
134 * before it got to the driver and the driver won't own all of it
136 #define bio_for_each_segment_all(bvl, bio, iter) \
137 for (bvl = bvec_init_iter_all(&iter); bio_next_segment((bio), &iter); )
139 static inline void bio_advance_iter(const struct bio
*bio
,
140 struct bvec_iter
*iter
, unsigned int bytes
)
142 iter
->bi_sector
+= bytes
>> 9;
144 if (bio_no_advance_iter(bio
))
145 iter
->bi_size
-= bytes
;
147 bvec_iter_advance(bio
->bi_io_vec
, iter
, bytes
);
148 /* TODO: It is reasonable to complete bio with error here. */
151 /* @bytes should be less or equal to bvec[i->bi_idx].bv_len */
152 static inline void bio_advance_iter_single(const struct bio
*bio
,
153 struct bvec_iter
*iter
,
156 iter
->bi_sector
+= bytes
>> 9;
158 if (bio_no_advance_iter(bio
))
159 iter
->bi_size
-= bytes
;
161 bvec_iter_advance_single(bio
->bi_io_vec
, iter
, bytes
);
164 #define __bio_for_each_segment(bvl, bio, iter, start) \
165 for (iter = (start); \
167 ((bvl = bio_iter_iovec((bio), (iter))), 1); \
168 bio_advance_iter_single((bio), &(iter), (bvl).bv_len))
170 #define bio_for_each_segment(bvl, bio, iter) \
171 __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
173 #define __bio_for_each_bvec(bvl, bio, iter, start) \
174 for (iter = (start); \
176 ((bvl = mp_bvec_iter_bvec((bio)->bi_io_vec, (iter))), 1); \
177 bio_advance_iter_single((bio), &(iter), (bvl).bv_len))
179 /* iterate over multi-page bvec */
180 #define bio_for_each_bvec(bvl, bio, iter) \
181 __bio_for_each_bvec(bvl, bio, iter, (bio)->bi_iter)
184 * Iterate over all multi-page bvecs. Drivers shouldn't use this version for the
185 * same reasons as bio_for_each_segment_all().
187 #define bio_for_each_bvec_all(bvl, bio, i) \
188 for (i = 0, bvl = bio_first_bvec_all(bio); \
189 i < (bio)->bi_vcnt; i++, bvl++) \
191 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
193 static inline unsigned bio_segments(struct bio
*bio
)
197 struct bvec_iter iter
;
200 * We special case discard/write same/write zeroes, because they
201 * interpret bi_size differently:
204 switch (bio_op(bio
)) {
206 case REQ_OP_SECURE_ERASE
:
207 case REQ_OP_WRITE_ZEROES
:
209 case REQ_OP_WRITE_SAME
:
215 bio_for_each_segment(bv
, bio
, iter
)
222 * get a reference to a bio, so it won't disappear. the intended use is
226 * submit_bio(rw, bio);
227 * if (bio->bi_flags ...)
231 * without the bio_get(), it could potentially complete I/O before submit_bio
232 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
235 static inline void bio_get(struct bio
*bio
)
237 bio
->bi_flags
|= (1 << BIO_REFFED
);
238 smp_mb__before_atomic();
239 atomic_inc(&bio
->__bi_cnt
);
242 static inline void bio_cnt_set(struct bio
*bio
, unsigned int count
)
245 bio
->bi_flags
|= (1 << BIO_REFFED
);
248 atomic_set(&bio
->__bi_cnt
, count
);
251 static inline bool bio_flagged(struct bio
*bio
, unsigned int bit
)
253 return (bio
->bi_flags
& (1U << bit
)) != 0;
256 static inline void bio_set_flag(struct bio
*bio
, unsigned int bit
)
258 bio
->bi_flags
|= (1U << bit
);
261 static inline void bio_clear_flag(struct bio
*bio
, unsigned int bit
)
263 bio
->bi_flags
&= ~(1U << bit
);
266 static inline void bio_get_first_bvec(struct bio
*bio
, struct bio_vec
*bv
)
268 *bv
= bio_iovec(bio
);
271 static inline void bio_get_last_bvec(struct bio
*bio
, struct bio_vec
*bv
)
273 struct bvec_iter iter
= bio
->bi_iter
;
276 if (unlikely(!bio_multiple_segments(bio
))) {
277 *bv
= bio_iovec(bio
);
281 bio_advance_iter(bio
, &iter
, iter
.bi_size
);
283 if (!iter
.bi_bvec_done
)
284 idx
= iter
.bi_idx
- 1;
285 else /* in the middle of bvec */
288 *bv
= bio
->bi_io_vec
[idx
];
291 * iter.bi_bvec_done records actual length of the last bvec
292 * if this bio ends in the middle of one io vector
294 if (iter
.bi_bvec_done
)
295 bv
->bv_len
= iter
.bi_bvec_done
;
298 static inline struct bio_vec
*bio_first_bvec_all(struct bio
*bio
)
300 WARN_ON_ONCE(bio_flagged(bio
, BIO_CLONED
));
301 return bio
->bi_io_vec
;
304 static inline struct page
*bio_first_page_all(struct bio
*bio
)
306 return bio_first_bvec_all(bio
)->bv_page
;
309 static inline struct bio_vec
*bio_last_bvec_all(struct bio
*bio
)
311 WARN_ON_ONCE(bio_flagged(bio
, BIO_CLONED
));
312 return &bio
->bi_io_vec
[bio
->bi_vcnt
- 1];
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 */
324 * bio integrity payload
326 struct bio_integrity_payload
{
327 struct bio
*bip_bio
; /* parent bio */
329 struct bvec_iter bip_iter
;
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 */
336 struct bvec_iter bio_iter
; /* for rewinding parent bio */
338 struct work_struct bip_work
; /* I/O completion */
340 struct bio_vec
*bip_vec
;
341 struct bio_vec bip_inline_vecs
[];/* embedded bvec array */
344 #if defined(CONFIG_BLK_DEV_INTEGRITY)
346 static inline struct bio_integrity_payload
*bio_integrity(struct bio
*bio
)
348 if (bio
->bi_opf
& REQ_INTEGRITY
)
349 return bio
->bi_integrity
;
354 static inline bool bio_integrity_flagged(struct bio
*bio
, enum bip_flags flag
)
356 struct bio_integrity_payload
*bip
= bio_integrity(bio
);
359 return bip
->bip_flags
& flag
;
364 static inline sector_t
bip_get_seed(struct bio_integrity_payload
*bip
)
366 return bip
->bip_iter
.bi_sector
;
369 static inline void bip_set_seed(struct bio_integrity_payload
*bip
,
372 bip
->bip_iter
.bi_sector
= seed
;
375 #endif /* CONFIG_BLK_DEV_INTEGRITY */
377 extern void bio_trim(struct bio
*bio
, int offset
, int size
);
378 extern struct bio
*bio_split(struct bio
*bio
, int sectors
,
379 gfp_t gfp
, struct bio_set
*bs
);
382 * bio_next_split - get next @sectors from a bio, splitting if necessary
384 * @sectors: number of sectors to split from the front of @bio
386 * @bs: bio set to allocate from
388 * Returns a bio representing the next @sectors of @bio - if the bio is smaller
389 * than @sectors, returns the original bio unchanged.
391 static inline struct bio
*bio_next_split(struct bio
*bio
, int sectors
,
392 gfp_t gfp
, struct bio_set
*bs
)
394 if (sectors
>= bio_sectors(bio
))
397 return bio_split(bio
, sectors
, gfp
, bs
);
401 BIOSET_NEED_BVECS
= BIT(0),
402 BIOSET_NEED_RESCUER
= BIT(1),
404 extern int bioset_init(struct bio_set
*, unsigned int, unsigned int, int flags
);
405 extern void bioset_exit(struct bio_set
*);
406 extern int biovec_init_pool(mempool_t
*pool
, int pool_entries
);
407 extern int bioset_init_from_src(struct bio_set
*bs
, struct bio_set
*src
);
409 extern struct bio
*bio_alloc_bioset(gfp_t
, unsigned int, struct bio_set
*);
410 extern void bio_put(struct bio
*);
412 extern void __bio_clone_fast(struct bio
*, struct bio
*);
413 extern struct bio
*bio_clone_fast(struct bio
*, gfp_t
, struct bio_set
*);
415 extern struct bio_set fs_bio_set
;
417 static inline struct bio
*bio_alloc(gfp_t gfp_mask
, unsigned int nr_iovecs
)
419 return bio_alloc_bioset(gfp_mask
, nr_iovecs
, &fs_bio_set
);
422 static inline struct bio
*bio_kmalloc(gfp_t gfp_mask
, unsigned int nr_iovecs
)
424 return bio_alloc_bioset(gfp_mask
, nr_iovecs
, NULL
);
427 extern blk_qc_t
submit_bio(struct bio
*);
429 extern void bio_endio(struct bio
*);
431 static inline void bio_io_error(struct bio
*bio
)
433 bio
->bi_status
= BLK_STS_IOERR
;
437 static inline void bio_wouldblock_error(struct bio
*bio
)
439 bio_set_flag(bio
, BIO_QUIET
);
440 bio
->bi_status
= BLK_STS_AGAIN
;
444 struct request_queue
;
446 extern int submit_bio_wait(struct bio
*bio
);
447 extern void bio_advance(struct bio
*, unsigned);
449 extern void bio_init(struct bio
*bio
, struct bio_vec
*table
,
450 unsigned short max_vecs
);
451 extern void bio_uninit(struct bio
*);
452 extern void bio_reset(struct bio
*);
453 void bio_chain(struct bio
*, struct bio
*);
455 extern int bio_add_page(struct bio
*, struct page
*, unsigned int,unsigned int);
456 extern int bio_add_pc_page(struct request_queue
*, struct bio
*, struct page
*,
457 unsigned int, unsigned int);
458 bool __bio_try_merge_page(struct bio
*bio
, struct page
*page
,
459 unsigned int len
, unsigned int off
, bool *same_page
);
460 void __bio_add_page(struct bio
*bio
, struct page
*page
,
461 unsigned int len
, unsigned int off
);
462 int bio_iov_iter_get_pages(struct bio
*bio
, struct iov_iter
*iter
);
463 void bio_release_pages(struct bio
*bio
, bool mark_dirty
);
464 extern void bio_set_pages_dirty(struct bio
*bio
);
465 extern void bio_check_pages_dirty(struct bio
*bio
);
467 extern void bio_copy_data_iter(struct bio
*dst
, struct bvec_iter
*dst_iter
,
468 struct bio
*src
, struct bvec_iter
*src_iter
);
469 extern void bio_copy_data(struct bio
*dst
, struct bio
*src
);
470 extern void bio_list_copy_data(struct bio
*dst
, struct bio
*src
);
471 extern void bio_free_pages(struct bio
*bio
);
472 void zero_fill_bio_iter(struct bio
*bio
, struct bvec_iter iter
);
473 void bio_truncate(struct bio
*bio
, unsigned new_size
);
474 void guard_bio_eod(struct bio
*bio
);
476 static inline void zero_fill_bio(struct bio
*bio
)
478 zero_fill_bio_iter(bio
, bio
->bi_iter
);
481 extern struct bio_vec
*bvec_alloc(gfp_t
, int, unsigned long *, mempool_t
*);
482 extern void bvec_free(mempool_t
*, struct bio_vec
*, unsigned int);
483 extern unsigned int bvec_nr_vecs(unsigned short idx
);
484 extern const char *bio_devname(struct bio
*bio
, char *buffer
);
486 #define bio_set_dev(bio, bdev) \
488 if ((bio)->bi_disk != (bdev)->bd_disk) \
489 bio_clear_flag(bio, BIO_THROTTLED);\
490 (bio)->bi_disk = (bdev)->bd_disk; \
491 (bio)->bi_partno = (bdev)->bd_partno; \
492 bio_associate_blkg(bio); \
495 #define bio_copy_dev(dst, src) \
497 (dst)->bi_disk = (src)->bi_disk; \
498 (dst)->bi_partno = (src)->bi_partno; \
499 bio_clone_blkg_association(dst, src); \
502 #define bio_dev(bio) \
503 disk_devt((bio)->bi_disk)
505 #ifdef CONFIG_BLK_CGROUP
506 void bio_associate_blkg(struct bio
*bio
);
507 void bio_associate_blkg_from_css(struct bio
*bio
,
508 struct cgroup_subsys_state
*css
);
509 void bio_clone_blkg_association(struct bio
*dst
, struct bio
*src
);
510 #else /* CONFIG_BLK_CGROUP */
511 static inline void bio_associate_blkg(struct bio
*bio
) { }
512 static inline void bio_associate_blkg_from_css(struct bio
*bio
,
513 struct cgroup_subsys_state
*css
)
515 static inline void bio_clone_blkg_association(struct bio
*dst
,
517 #endif /* CONFIG_BLK_CGROUP */
519 #ifdef CONFIG_HIGHMEM
521 * remember never ever reenable interrupts between a bvec_kmap_irq and
524 static inline char *bvec_kmap_irq(struct bio_vec
*bvec
, unsigned long *flags
)
529 * might not be a highmem page, but the preempt/irq count
530 * balancing is a lot nicer this way
532 local_irq_save(*flags
);
533 addr
= (unsigned long) kmap_atomic(bvec
->bv_page
);
535 BUG_ON(addr
& ~PAGE_MASK
);
537 return (char *) addr
+ bvec
->bv_offset
;
540 static inline void bvec_kunmap_irq(char *buffer
, unsigned long *flags
)
542 unsigned long ptr
= (unsigned long) buffer
& PAGE_MASK
;
544 kunmap_atomic((void *) ptr
);
545 local_irq_restore(*flags
);
549 static inline char *bvec_kmap_irq(struct bio_vec
*bvec
, unsigned long *flags
)
551 return page_address(bvec
->bv_page
) + bvec
->bv_offset
;
554 static inline void bvec_kunmap_irq(char *buffer
, unsigned long *flags
)
561 * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
563 * A bio_list anchors a singly-linked list of bios chained through the bi_next
564 * member of the bio. The bio_list also caches the last list member to allow
565 * fast access to the tail.
572 static inline int bio_list_empty(const struct bio_list
*bl
)
574 return bl
->head
== NULL
;
577 static inline void bio_list_init(struct bio_list
*bl
)
579 bl
->head
= bl
->tail
= NULL
;
582 #define BIO_EMPTY_LIST { NULL, NULL }
584 #define bio_list_for_each(bio, bl) \
585 for (bio = (bl)->head; bio; bio = bio->bi_next)
587 static inline unsigned bio_list_size(const struct bio_list
*bl
)
592 bio_list_for_each(bio
, bl
)
598 static inline void bio_list_add(struct bio_list
*bl
, struct bio
*bio
)
603 bl
->tail
->bi_next
= bio
;
610 static inline void bio_list_add_head(struct bio_list
*bl
, struct bio
*bio
)
612 bio
->bi_next
= bl
->head
;
620 static inline void bio_list_merge(struct bio_list
*bl
, struct bio_list
*bl2
)
626 bl
->tail
->bi_next
= bl2
->head
;
628 bl
->head
= bl2
->head
;
630 bl
->tail
= bl2
->tail
;
633 static inline void bio_list_merge_head(struct bio_list
*bl
,
634 struct bio_list
*bl2
)
640 bl2
->tail
->bi_next
= bl
->head
;
642 bl
->tail
= bl2
->tail
;
644 bl
->head
= bl2
->head
;
647 static inline struct bio
*bio_list_peek(struct bio_list
*bl
)
652 static inline struct bio
*bio_list_pop(struct bio_list
*bl
)
654 struct bio
*bio
= bl
->head
;
657 bl
->head
= bl
->head
->bi_next
;
667 static inline struct bio
*bio_list_get(struct bio_list
*bl
)
669 struct bio
*bio
= bl
->head
;
671 bl
->head
= bl
->tail
= NULL
;
677 * Increment chain count for the bio. Make sure the CHAIN flag update
678 * is visible before the raised count.
680 static inline void bio_inc_remaining(struct bio
*bio
)
682 bio_set_flag(bio
, BIO_CHAIN
);
683 smp_mb__before_atomic();
684 atomic_inc(&bio
->__bi_remaining
);
688 * bio_set is used to allow other portions of the IO system to
689 * allocate their own private memory pools for bio and iovec structures.
690 * These memory pools in turn all allocate from the bio_slab
691 * and the bvec_slabs[].
693 #define BIO_POOL_SIZE 2
696 struct kmem_cache
*bio_slab
;
697 unsigned int front_pad
;
701 #if defined(CONFIG_BLK_DEV_INTEGRITY)
702 mempool_t bio_integrity_pool
;
703 mempool_t bvec_integrity_pool
;
707 * Deadlock avoidance for stacking block drivers: see comments in
708 * bio_alloc_bioset() for details
710 spinlock_t rescue_lock
;
711 struct bio_list rescue_list
;
712 struct work_struct rescue_work
;
713 struct workqueue_struct
*rescue_workqueue
;
719 struct kmem_cache
*slab
;
722 static inline bool bioset_initialized(struct bio_set
*bs
)
724 return bs
->bio_slab
!= NULL
;
727 #if defined(CONFIG_BLK_DEV_INTEGRITY)
729 #define bip_for_each_vec(bvl, bip, iter) \
730 for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
732 #define bio_for_each_integrity_vec(_bvl, _bio, _iter) \
734 bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
736 extern struct bio_integrity_payload
*bio_integrity_alloc(struct bio
*, gfp_t
, unsigned int);
737 extern int bio_integrity_add_page(struct bio
*, struct page
*, unsigned int, unsigned int);
738 extern bool bio_integrity_prep(struct bio
*);
739 extern void bio_integrity_advance(struct bio
*, unsigned int);
740 extern void bio_integrity_trim(struct bio
*);
741 extern int bio_integrity_clone(struct bio
*, struct bio
*, gfp_t
);
742 extern int bioset_integrity_create(struct bio_set
*, int);
743 extern void bioset_integrity_free(struct bio_set
*);
744 extern void bio_integrity_init(void);
746 #else /* CONFIG_BLK_DEV_INTEGRITY */
748 static inline void *bio_integrity(struct bio
*bio
)
753 static inline int bioset_integrity_create(struct bio_set
*bs
, int pool_size
)
758 static inline void bioset_integrity_free (struct bio_set
*bs
)
763 static inline bool bio_integrity_prep(struct bio
*bio
)
768 static inline int bio_integrity_clone(struct bio
*bio
, struct bio
*bio_src
,
774 static inline void bio_integrity_advance(struct bio
*bio
,
775 unsigned int bytes_done
)
780 static inline void bio_integrity_trim(struct bio
*bio
)
785 static inline void bio_integrity_init(void)
790 static inline bool bio_integrity_flagged(struct bio
*bio
, enum bip_flags flag
)
795 static inline void *bio_integrity_alloc(struct bio
* bio
, gfp_t gfp
,
798 return ERR_PTR(-EINVAL
);
801 static inline int bio_integrity_add_page(struct bio
*bio
, struct page
*page
,
802 unsigned int len
, unsigned int offset
)
807 #endif /* CONFIG_BLK_DEV_INTEGRITY */
810 * Mark a bio as polled. Note that for async polled IO, the caller must
811 * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
812 * We cannot block waiting for requests on polled IO, as those completions
813 * must be found by the caller. This is different than IRQ driven IO, where
814 * it's safe to wait for IO to complete.
816 static inline void bio_set_polled(struct bio
*bio
, struct kiocb
*kiocb
)
818 bio
->bi_opf
|= REQ_HIPRI
;
819 if (!is_sync_kiocb(kiocb
))
820 bio
->bi_opf
|= REQ_NOWAIT
;
823 #endif /* __LINUX_BIO_H */