include/linux/bio.h - kernel/msm-4.9 - Gitiles

 /*
  * 2.5 block I/O model
  *
  * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  *
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public Licens
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
  */
 #ifndef __LINUX_BIO_H
 #define __LINUX_BIO_H

 #include <linux/highmem.h>
 #include <linux/mempool.h>
 #include <linux/ioprio.h>
 #include <linux/bug.h>

 #ifdef CONFIG_BLOCK

 #include <asm/io.h>

 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
 #include <linux/blk_types.h>

 #define BIO_DEBUG

 #ifdef BIO_DEBUG
 #define BIO_BUG_ON	BUG_ON
 #else
 #define BIO_BUG_ON
 #endif

 #define BIO_MAX_PAGES		256
 #define BIO_MAX_SIZE		(BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
 #define BIO_MAX_SECTORS		(BIO_MAX_SIZE >> 9)

 /*
  * upper 16 bits of bi_rw define the io priority of this bio
  */
 #define BIO_PRIO_SHIFT	(8 * sizeof(unsigned long) - IOPRIO_BITS)
 #define bio_prio(bio)	((bio)->bi_rw >> BIO_PRIO_SHIFT)
 #define bio_prio_valid(bio)	ioprio_valid(bio_prio(bio))

 #define bio_set_prio(bio, prio)		do {			\
 	WARN_ON(prio >= (1 << IOPRIO_BITS));			\
 	(bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);		\
 	(bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);	\
 } while (0)

 /*
  * various member access, note that bio_data should of course not be used
  * on highmem page vectors
  */
 #define bio_iovec_idx(bio, idx)	(&((bio)->bi_io_vec[(idx)]))
 #define bio_iovec(bio)		bio_iovec_idx((bio), (bio)->bi_idx)
 #define bio_page(bio)		bio_iovec((bio))->bv_page
 #define bio_offset(bio)		bio_iovec((bio))->bv_offset
 #define bio_segments(bio)	((bio)->bi_vcnt - (bio)->bi_idx)
 #define bio_sectors(bio)	((bio)->bi_size >> 9)

 static inline unsigned int bio_cur_bytes(struct bio *bio)
 {
 	if (bio->bi_vcnt)
 		return bio_iovec(bio)->bv_len;
 	else /* dataless requests such as discard */
 		return bio->bi_size;
 }

 static inline void *bio_data(struct bio *bio)
 {
 	if (bio->bi_vcnt)
 		return page_address(bio_page(bio)) + bio_offset(bio);

 	return NULL;
 }

 static inline int bio_has_allocated_vec(struct bio *bio)
 {
 	return bio->bi_io_vec && bio->bi_io_vec != bio->bi_inline_vecs;
 }

 /*
  * will die
  */
 #define bio_to_phys(bio)	(page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
 #define bvec_to_phys(bv)	(page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)

 /*
  * queues that have highmem support enabled may still need to revert to
  * PIO transfers occasionally and thus map high pages temporarily. For
  * permanent PIO fall back, user is probably better off disabling highmem
  * I/O completely on that queue (see ide-dma for example)
  */
 #define __bio_kmap_atomic(bio, idx, kmtype)				\
 	(kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page) +	\
 		bio_iovec_idx((bio), (idx))->bv_offset)

 #define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr)

 /*
  * merge helpers etc
  */

 #define __BVEC_END(bio)		bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
 #define __BVEC_START(bio)	bio_iovec_idx((bio), (bio)->bi_idx)

 /* Default implementation of BIOVEC_PHYS_MERGEABLE */
 #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
 	((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))

 /*
  * allow arch override, for eg virtualized architectures (put in asm/io.h)
  */
 #ifndef BIOVEC_PHYS_MERGEABLE
 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
 	__BIOVEC_PHYS_MERGEABLE(vec1, vec2)
 #endif

 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 	(((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 	__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
 #define BIO_SEG_BOUNDARY(q, b1, b2) \
 	BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))

 #define bio_io_error(bio) bio_endio((bio), -EIO)

 /*
  * drivers should not use the __ version unless they _really_ want to
  * run through the entire bio and not just pending pieces
  */
 #define __bio_for_each_segment(bvl, bio, i, start_idx)			\
 	for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);	\
 	     i < (bio)->bi_vcnt;					\
 	     bvl++, i++)

 #define bio_for_each_segment(bvl, bio, i)				\
 	__bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)

 /*
  * get a reference to a bio, so it won't disappear. the intended use is
  * something like:
  *
  * bio_get(bio);
  * submit_bio(rw, bio);
  * if (bio->bi_flags ...)
  *	do_something
  * bio_put(bio);
  *
  * without the bio_get(), it could potentially complete I/O before submit_bio
  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
  * runs
  */
 #define bio_get(bio)	atomic_inc(&(bio)->bi_cnt)

 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 /*
  * bio integrity payload
  */
 struct bio_integrity_payload {
 	struct bio		*bip_bio;	/* parent bio */

 	sector_t		bip_sector;	/* virtual start sector */

 	void			*bip_buf;	/* generated integrity data */
 	bio_end_io_t		*bip_end_io;	/* saved I/O completion fn */

 	unsigned int		bip_size;

 	unsigned short		bip_slab;	/* slab the bip came from */
 	unsigned short		bip_vcnt;	/* # of integrity bio_vecs */
 	unsigned short		bip_idx;	/* current bip_vec index */

 	struct work_struct	bip_work;	/* I/O completion */
 	struct bio_vec		bip_vec[0];	/* embedded bvec array */
 };
 #endif /* CONFIG_BLK_DEV_INTEGRITY */

 /*
  * A bio_pair is used when we need to split a bio.
  * This can only happen for a bio that refers to just one
  * page of data, and in the unusual situation when the
  * page crosses a chunk/device boundary
  *
  * The address of the master bio is stored in bio1.bi_private
  * The address of the pool the pair was allocated from is stored
  *   in bio2.bi_private
  */
 struct bio_pair {
 	struct bio			bio1, bio2;
 	struct bio_vec			bv1, bv2;
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 	struct bio_integrity_payload	bip1, bip2;
 	struct bio_vec			iv1, iv2;
 #endif
 	atomic_t			cnt;
 	int				error;
 };
 extern struct bio_pair *bio_split(struct bio *bi, int first_sectors);
 extern void bio_pair_release(struct bio_pair *dbio);

 extern struct bio_set *bioset_create(unsigned int, unsigned int);
 extern void bioset_free(struct bio_set *);

 extern struct bio *bio_alloc(gfp_t, unsigned int);
 extern struct bio *bio_kmalloc(gfp_t, unsigned int);
 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 extern void bio_put(struct bio *);
 extern void bio_free(struct bio *, struct bio_set *);

 extern void bio_endio(struct bio *, int);
 struct request_queue;
 extern int bio_phys_segments(struct request_queue *, struct bio *);

 extern void __bio_clone(struct bio *, struct bio *);
 extern struct bio *bio_clone(struct bio *, gfp_t);

 extern void bio_init(struct bio *);

 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 			   unsigned int, unsigned int);
 extern int bio_get_nr_vecs(struct block_device *);
 extern sector_t bio_sector_offset(struct bio *, unsigned short, unsigned int);
 extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 				unsigned long, unsigned int, int, gfp_t);
 struct sg_iovec;
 struct rq_map_data;
 extern struct bio *bio_map_user_iov(struct request_queue *,
 				    struct block_device *,
 				    struct sg_iovec *, int, int, gfp_t);
 extern void bio_unmap_user(struct bio *);
 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 				gfp_t);
 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 				 gfp_t, int);
 extern void bio_set_pages_dirty(struct bio *bio);
 extern void bio_check_pages_dirty(struct bio *bio);

 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 # error	"You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 #endif
 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 extern void bio_flush_dcache_pages(struct bio *bi);
 #else
 static inline void bio_flush_dcache_pages(struct bio *bi)
 {
 }
 #endif

 extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
 				 unsigned long, unsigned int, int, gfp_t);
 extern struct bio *bio_copy_user_iov(struct request_queue *,
 				     struct rq_map_data *, struct sg_iovec *,
 				     int, int, gfp_t);
 extern int bio_uncopy_user(struct bio *);
 void zero_fill_bio(struct bio *bio);
 extern struct bio_vec *bvec_alloc_bs(gfp_t, int, unsigned long *, struct bio_set *);
 extern void bvec_free_bs(struct bio_set *, struct bio_vec *, unsigned int);
 extern unsigned int bvec_nr_vecs(unsigned short idx);

 /*
  * bio_set is used to allow other portions of the IO system to
  * allocate their own private memory pools for bio and iovec structures.
  * These memory pools in turn all allocate from the bio_slab
  * and the bvec_slabs[].
  */
 #define BIO_POOL_SIZE 2
 #define BIOVEC_NR_POOLS 6
 #define BIOVEC_MAX_IDX	(BIOVEC_NR_POOLS - 1)

 struct bio_set {
 	struct kmem_cache *bio_slab;
 	unsigned int front_pad;

 	mempool_t *bio_pool;
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 	mempool_t *bio_integrity_pool;
 #endif
 	mempool_t *bvec_pool;
 };

 struct biovec_slab {
 	int nr_vecs;
 	char *name;
 	struct kmem_cache *slab;
 };

 extern struct bio_set *fs_bio_set;

 /*
  * a small number of entries is fine, not going to be performance critical.
  * basically we just need to survive
  */
 #define BIO_SPLIT_ENTRIES 2

 #ifdef CONFIG_HIGHMEM
 /*
  * remember never ever reenable interrupts between a bvec_kmap_irq and
  * bvec_kunmap_irq!
  */
 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 {
 	unsigned long addr;

 	/*
 	 * might not be a highmem page, but the preempt/irq count
 	 * balancing is a lot nicer this way
 	 */
 	local_irq_save(*flags);
 	addr = (unsigned long) kmap_atomic(bvec->bv_page);

 	BUG_ON(addr & ~PAGE_MASK);

 	return (char *) addr + bvec->bv_offset;
 }

 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 {
 	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;

 	kunmap_atomic((void *) ptr);
 	local_irq_restore(*flags);
 }

 #else
 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 {
 	return page_address(bvec->bv_page) + bvec->bv_offset;
 }

 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 {
 	*flags = 0;
 }
 #endif

 static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 				   unsigned long *flags)
 {
 	return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
 }
 #define __bio_kunmap_irq(buf, flags)	bvec_kunmap_irq(buf, flags)

 #define bio_kmap_irq(bio, flags) \
 	__bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 #define bio_kunmap_irq(buf,flags)	__bio_kunmap_irq(buf, flags)

 /*
  * Check whether this bio carries any data or not. A NULL bio is allowed.
  */
 static inline int bio_has_data(struct bio *bio)
 {
 	return bio && bio->bi_io_vec != NULL;
 }

 /*
  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
  *
  * A bio_list anchors a singly-linked list of bios chained through the bi_next
  * member of the bio.  The bio_list also caches the last list member to allow
  * fast access to the tail.
  */
 struct bio_list {
 	struct bio *head;
 	struct bio *tail;
 };

 static inline int bio_list_empty(const struct bio_list *bl)
 {
 	return bl->head == NULL;
 }

 static inline void bio_list_init(struct bio_list *bl)
 {
 	bl->head = bl->tail = NULL;
 }

 #define bio_list_for_each(bio, bl) \
 	for (bio = (bl)->head; bio; bio = bio->bi_next)

 static inline unsigned bio_list_size(const struct bio_list *bl)
 {
 	unsigned sz = 0;
 	struct bio *bio;

 	bio_list_for_each(bio, bl)
 		sz++;

 	return sz;
 }

 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 {
 	bio->bi_next = NULL;

 	if (bl->tail)
 		bl->tail->bi_next = bio;
 	else
 		bl->head = bio;

 	bl->tail = bio;
 }

 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 {
 	bio->bi_next = bl->head;

 	bl->head = bio;

 	if (!bl->tail)
 		bl->tail = bio;
 }

 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 {
 	if (!bl2->head)
 		return;

 	if (bl->tail)
 		bl->tail->bi_next = bl2->head;
 	else
 		bl->head = bl2->head;

 	bl->tail = bl2->tail;
 }

 static inline void bio_list_merge_head(struct bio_list *bl,
 				       struct bio_list *bl2)
 {
 	if (!bl2->head)
 		return;

 	if (bl->head)
 		bl2->tail->bi_next = bl->head;
 	else
 		bl->tail = bl2->tail;

 	bl->head = bl2->head;
 }

 static inline struct bio *bio_list_peek(struct bio_list *bl)
 {
 	return bl->head;
 }

 static inline struct bio *bio_list_pop(struct bio_list *bl)
 {
 	struct bio *bio = bl->head;

 	if (bio) {
 		bl->head = bl->head->bi_next;
 		if (!bl->head)
 			bl->tail = NULL;

 		bio->bi_next = NULL;
 	}

 	return bio;
 }

 static inline struct bio *bio_list_get(struct bio_list *bl)
 {
 	struct bio *bio = bl->head;

 	bl->head = bl->tail = NULL;

 	return bio;
 }

 #if defined(CONFIG_BLK_DEV_INTEGRITY)

 #define bip_vec_idx(bip, idx)	(&(bip->bip_vec[(idx)]))
 #define bip_vec(bip)		bip_vec_idx(bip, 0)

 #define __bip_for_each_vec(bvl, bip, i, start_idx)			\
 	for (bvl = bip_vec_idx((bip), (start_idx)), i = (start_idx);	\
 	     i < (bip)->bip_vcnt;					\
 	     bvl++, i++)

 #define bip_for_each_vec(bvl, bip, i)					\
 	__bip_for_each_vec(bvl, bip, i, (bip)->bip_idx)

 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)			\
 	for_each_bio(_bio)						\
 		bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)

 #define bio_integrity(bio) (bio->bi_integrity != NULL)

 extern struct bio_integrity_payload *bio_integrity_alloc_bioset(struct bio *, gfp_t, unsigned int, struct bio_set *);
 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 extern void bio_integrity_free(struct bio *, struct bio_set *);
 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 extern int bio_integrity_enabled(struct bio *bio);
 extern int bio_integrity_set_tag(struct bio *, void *, unsigned int);
 extern int bio_integrity_get_tag(struct bio *, void *, unsigned int);
 extern int bio_integrity_prep(struct bio *);
 extern void bio_integrity_endio(struct bio *, int);
 extern void bio_integrity_advance(struct bio *, unsigned int);
 extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
 extern void bio_integrity_split(struct bio *, struct bio_pair *, int);
 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t, struct bio_set *);
 extern int bioset_integrity_create(struct bio_set *, int);
 extern void bioset_integrity_free(struct bio_set *);
 extern void bio_integrity_init(void);

 #else /* CONFIG_BLK_DEV_INTEGRITY */

 static inline int bio_integrity(struct bio *bio)
 {
 	return 0;
 }

 static inline int bio_integrity_enabled(struct bio *bio)
 {
 	return 0;
 }

 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 {
 	return 0;
 }

 static inline void bioset_integrity_free (struct bio_set *bs)
 {
 	return;
 }

 static inline int bio_integrity_prep(struct bio *bio)
 {
 	return 0;
 }

 static inline void bio_integrity_free(struct bio *bio, struct bio_set *bs)
 {
 	return;
 }

 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 				      gfp_t gfp_mask, struct bio_set *bs)
 {
 	return 0;
 }

 static inline void bio_integrity_split(struct bio *bio, struct bio_pair *bp,
 				       int sectors)
 {
 	return;
 }

 static inline void bio_integrity_advance(struct bio *bio,
 					 unsigned int bytes_done)
 {
 	return;
 }

 static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
 				      unsigned int sectors)
 {
 	return;
 }

 static inline void bio_integrity_init(void)
 {
 	return;
 }

 #endif /* CONFIG_BLK_DEV_INTEGRITY */

 #endif /* CONFIG_BLOCK */
 #endif /* __LINUX_BIO_H */
	/*
	* 2.5 block I/O model
	*
	* Copyright (C) 2001 Jens Axboe <axboe@suse.de>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	*
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public Licens
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
	*/
	#ifndef __LINUX_BIO_H
	#define __LINUX_BIO_H

	#include <linux/highmem.h>
	#include <linux/mempool.h>
	#include <linux/ioprio.h>
	#include <linux/bug.h>

	#ifdef CONFIG_BLOCK

	#include <asm/io.h>

	/* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
	#include <linux/blk_types.h>

	#define BIO_DEBUG

	#ifdef BIO_DEBUG
	#define BIO_BUG_ON BUG_ON
	#else
	#define BIO_BUG_ON
	#endif

	#define BIO_MAX_PAGES 256
	#define BIO_MAX_SIZE (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
	#define BIO_MAX_SECTORS (BIO_MAX_SIZE >> 9)

	/*
	* upper 16 bits of bi_rw define the io priority of this bio
	*/
	#define BIO_PRIO_SHIFT (8 * sizeof(unsigned long) - IOPRIO_BITS)
	#define bio_prio(bio) ((bio)->bi_rw >> BIO_PRIO_SHIFT)
	#define bio_prio_valid(bio) ioprio_valid(bio_prio(bio))

	#define bio_set_prio(bio, prio) do { \
	WARN_ON(prio >= (1 << IOPRIO_BITS)); \
	(bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1); \
	(bio)->bi_rw \|= ((unsigned long) (prio) << BIO_PRIO_SHIFT); \
	} while (0)

	/*
	* various member access, note that bio_data should of course not be used
	* on highmem page vectors
	*/
	#define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
	#define bio_iovec(bio) bio_iovec_idx((bio), (bio)->bi_idx)
	#define bio_page(bio) bio_iovec((bio))->bv_page
	#define bio_offset(bio) bio_iovec((bio))->bv_offset
	#define bio_segments(bio) ((bio)->bi_vcnt - (bio)->bi_idx)
	#define bio_sectors(bio) ((bio)->bi_size >> 9)

	static inline unsigned int bio_cur_bytes(struct bio *bio)
	{
	if (bio->bi_vcnt)
	return bio_iovec(bio)->bv_len;
	else /* dataless requests such as discard */
	return bio->bi_size;
	}

	static inline void bio_data(struct bio bio)
	{
	if (bio->bi_vcnt)
	return page_address(bio_page(bio)) + bio_offset(bio);

	return NULL;
	}

	static inline int bio_has_allocated_vec(struct bio *bio)
	{
	return bio->bi_io_vec && bio->bi_io_vec != bio->bi_inline_vecs;
	}

	/*
	* will die
	*/
	#define bio_to_phys(bio) (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
	#define bvec_to_phys(bv) (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)

	/*
	* queues that have highmem support enabled may still need to revert to
	* PIO transfers occasionally and thus map high pages temporarily. For
	* permanent PIO fall back, user is probably better off disabling highmem
	* I/O completely on that queue (see ide-dma for example)
	*/
	#define __bio_kmap_atomic(bio, idx, kmtype) \
	(kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page) + \
	bio_iovec_idx((bio), (idx))->bv_offset)

	#define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr)

	/*
	* merge helpers etc
	*/

	#define __BVEC_END(bio) bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
	#define __BVEC_START(bio) bio_iovec_idx((bio), (bio)->bi_idx)

	/* Default implementation of BIOVEC_PHYS_MERGEABLE */
	#define __BIOVEC_PHYS_MERGEABLE(vec1, vec2) \
	((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))

	/*
	* allow arch override, for eg virtualized architectures (put in asm/io.h)
	*/
	#ifndef BIOVEC_PHYS_MERGEABLE
	#define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \
	__BIOVEC_PHYS_MERGEABLE(vec1, vec2)
	#endif

	#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
	(((addr1) \| (mask)) == (((addr2) - 1) \| (mask)))
	#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
	__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
	#define BIO_SEG_BOUNDARY(q, b1, b2) \
	BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))

	#define bio_io_error(bio) bio_endio((bio), -EIO)

	/*
	* drivers should not use the __ version unless they _really_ want to
	* run through the entire bio and not just pending pieces
	*/
	#define __bio_for_each_segment(bvl, bio, i, start_idx) \
	for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx); \
	i < (bio)->bi_vcnt; \
	bvl++, i++)

	#define bio_for_each_segment(bvl, bio, i) \
	__bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)

	/*
	* get a reference to a bio, so it won't disappear. the intended use is
	* something like:
	*
	* bio_get(bio);
	* submit_bio(rw, bio);
	* if (bio->bi_flags ...)
	* do_something
	* bio_put(bio);
	*
	* without the bio_get(), it could potentially complete I/O before submit_bio
	* returns. and then bio would be freed memory when if (bio->bi_flags ...)
	* runs
	*/
	#define bio_get(bio) atomic_inc(&(bio)->bi_cnt)

	#if defined(CONFIG_BLK_DEV_INTEGRITY)
	/*
	* bio integrity payload
	*/
	struct bio_integrity_payload {
	struct bio bip_bio; / parent bio */

	sector_t bip_sector; /* virtual start sector */

	void bip_buf; / generated integrity data */
	bio_end_io_t bip_end_io; / saved I/O completion fn */

	unsigned int bip_size;

	unsigned short bip_slab; /* slab the bip came from */
	unsigned short bip_vcnt; /* # of integrity bio_vecs */
	unsigned short bip_idx; /* current bip_vec index */

	struct work_struct bip_work; /* I/O completion */
	struct bio_vec bip_vec[0]; /* embedded bvec array */
	};
	#endif /* CONFIG_BLK_DEV_INTEGRITY */

	/*
	* A bio_pair is used when we need to split a bio.
	* This can only happen for a bio that refers to just one
	* page of data, and in the unusual situation when the
	* page crosses a chunk/device boundary
	*
	* The address of the master bio is stored in bio1.bi_private
	* The address of the pool the pair was allocated from is stored
	* in bio2.bi_private
	*/
	struct bio_pair {
	struct bio bio1, bio2;
	struct bio_vec bv1, bv2;
	#if defined(CONFIG_BLK_DEV_INTEGRITY)
	struct bio_integrity_payload bip1, bip2;
	struct bio_vec iv1, iv2;
	#endif
	atomic_t cnt;
	int error;
	};
	extern struct bio_pair bio_split(struct bio bi, int first_sectors);
	extern void bio_pair_release(struct bio_pair *dbio);

	extern struct bio_set *bioset_create(unsigned int, unsigned int);
	extern void bioset_free(struct bio_set *);

	extern struct bio *bio_alloc(gfp_t, unsigned int);
	extern struct bio *bio_kmalloc(gfp_t, unsigned int);
	extern struct bio bio_alloc_bioset(gfp_t, int, struct bio_set );
	extern void bio_put(struct bio *);
	extern void bio_free(struct bio , struct bio_set );

	extern void bio_endio(struct bio *, int);
	struct request_queue;
	extern int bio_phys_segments(struct request_queue , struct bio );

	extern void __bio_clone(struct bio , struct bio );
	extern struct bio bio_clone(struct bio , gfp_t);

	extern void bio_init(struct bio *);

	extern int bio_add_page(struct bio , struct page , unsigned int,unsigned int);
	extern int bio_add_pc_page(struct request_queue , struct bio , struct page *,
	unsigned int, unsigned int);
	extern int bio_get_nr_vecs(struct block_device *);
	extern sector_t bio_sector_offset(struct bio *, unsigned short, unsigned int);
	extern struct bio bio_map_user(struct request_queue , struct block_device *,
	unsigned long, unsigned int, int, gfp_t);
	struct sg_iovec;
	struct rq_map_data;
	extern struct bio bio_map_user_iov(struct request_queue ,
	struct block_device *,
	struct sg_iovec *, int, int, gfp_t);
	extern void bio_unmap_user(struct bio *);
	extern struct bio bio_map_kern(struct request_queue , void *, unsigned int,
	gfp_t);
	extern struct bio bio_copy_kern(struct request_queue , void *, unsigned int,
	gfp_t, int);
	extern void bio_set_pages_dirty(struct bio *bio);
	extern void bio_check_pages_dirty(struct bio *bio);

	#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
	# error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
	#endif
	#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
	extern void bio_flush_dcache_pages(struct bio *bi);
	#else
	static inline void bio_flush_dcache_pages(struct bio *bi)
	{
	}
	#endif

	extern struct bio bio_copy_user(struct request_queue , struct rq_map_data *,
	unsigned long, unsigned int, int, gfp_t);
	extern struct bio bio_copy_user_iov(struct request_queue ,
	struct rq_map_data , struct sg_iovec ,
	int, int, gfp_t);
	extern int bio_uncopy_user(struct bio *);
	void zero_fill_bio(struct bio *bio);
	extern struct bio_vec bvec_alloc_bs(gfp_t, int, unsigned long , struct bio_set *);
	extern void bvec_free_bs(struct bio_set , struct bio_vec , unsigned int);
	extern unsigned int bvec_nr_vecs(unsigned short idx);

	/*
	* bio_set is used to allow other portions of the IO system to
	* allocate their own private memory pools for bio and iovec structures.
	* These memory pools in turn all allocate from the bio_slab
	* and the bvec_slabs[].
	*/
	#define BIO_POOL_SIZE 2
	#define BIOVEC_NR_POOLS 6
	#define BIOVEC_MAX_IDX (BIOVEC_NR_POOLS - 1)

	struct bio_set {
	struct kmem_cache *bio_slab;
	unsigned int front_pad;

	mempool_t *bio_pool;
	#if defined(CONFIG_BLK_DEV_INTEGRITY)
	mempool_t *bio_integrity_pool;
	#endif
	mempool_t *bvec_pool;
	};

	struct biovec_slab {
	int nr_vecs;
	char *name;
	struct kmem_cache *slab;
	};

	extern struct bio_set *fs_bio_set;

	/*
	* a small number of entries is fine, not going to be performance critical.
	* basically we just need to survive
	*/
	#define BIO_SPLIT_ENTRIES 2

	#ifdef CONFIG_HIGHMEM
	/*
	* remember never ever reenable interrupts between a bvec_kmap_irq and
	* bvec_kunmap_irq!
	*/
	static inline char bvec_kmap_irq(struct bio_vec bvec, unsigned long *flags)
	{
	unsigned long addr;

	/*
	* might not be a highmem page, but the preempt/irq count
	* balancing is a lot nicer this way
	*/
	local_irq_save(*flags);
	addr = (unsigned long) kmap_atomic(bvec->bv_page);

	BUG_ON(addr & ~PAGE_MASK);

	return (char *) addr + bvec->bv_offset;
	}

	static inline void bvec_kunmap_irq(char buffer, unsigned long flags)
	{
	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;

	kunmap_atomic((void *) ptr);
	local_irq_restore(*flags);
	}

	#else
	static inline char bvec_kmap_irq(struct bio_vec bvec, unsigned long *flags)
	{
	return page_address(bvec->bv_page) + bvec->bv_offset;
	}

	static inline void bvec_kunmap_irq(char buffer, unsigned long flags)
	{
	*flags = 0;
	}
	#endif

	static inline char __bio_kmap_irq(struct bio bio, unsigned short idx,
	unsigned long *flags)
	{
	return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
	}
	#define __bio_kunmap_irq(buf, flags) bvec_kunmap_irq(buf, flags)

	#define bio_kmap_irq(bio, flags) \
	__bio_kmap_irq((bio), (bio)->bi_idx, (flags))
	#define bio_kunmap_irq(buf,flags) __bio_kunmap_irq(buf, flags)

	/*
	* Check whether this bio carries any data or not. A NULL bio is allowed.
	*/
	static inline int bio_has_data(struct bio *bio)
	{
	return bio && bio->bi_io_vec != NULL;
	}

	/*
	* BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
	*
	* A bio_list anchors a singly-linked list of bios chained through the bi_next
	* member of the bio. The bio_list also caches the last list member to allow
	* fast access to the tail.
	*/
	struct bio_list {
	struct bio *head;
	struct bio *tail;
	};

	static inline int bio_list_empty(const struct bio_list *bl)
	{
	return bl->head == NULL;
	}

	static inline void bio_list_init(struct bio_list *bl)
	{
	bl->head = bl->tail = NULL;
	}

	#define bio_list_for_each(bio, bl) \
	for (bio = (bl)->head; bio; bio = bio->bi_next)

	static inline unsigned bio_list_size(const struct bio_list *bl)
	{
	unsigned sz = 0;
	struct bio *bio;

	bio_list_for_each(bio, bl)
	sz++;

	return sz;
	}

	static inline void bio_list_add(struct bio_list bl, struct bio bio)
	{
	bio->bi_next = NULL;

	if (bl->tail)
	bl->tail->bi_next = bio;
	else
	bl->head = bio;

	bl->tail = bio;
	}

	static inline void bio_list_add_head(struct bio_list bl, struct bio bio)
	{
	bio->bi_next = bl->head;

	bl->head = bio;

	if (!bl->tail)
	bl->tail = bio;
	}

	static inline void bio_list_merge(struct bio_list bl, struct bio_list bl2)
	{
	if (!bl2->head)
	return;

	if (bl->tail)
	bl->tail->bi_next = bl2->head;
	else
	bl->head = bl2->head;

	bl->tail = bl2->tail;
	}

	static inline void bio_list_merge_head(struct bio_list *bl,
	struct bio_list *bl2)
	{
	if (!bl2->head)
	return;

	if (bl->head)
	bl2->tail->bi_next = bl->head;
	else
	bl->tail = bl2->tail;

	bl->head = bl2->head;
	}

	static inline struct bio bio_list_peek(struct bio_list bl)
	{
	return bl->head;
	}

	static inline struct bio bio_list_pop(struct bio_list bl)
	{
	struct bio *bio = bl->head;

	if (bio) {
	bl->head = bl->head->bi_next;
	if (!bl->head)
	bl->tail = NULL;

	bio->bi_next = NULL;
	}

	return bio;
	}

	static inline struct bio bio_list_get(struct bio_list bl)
	{
	struct bio *bio = bl->head;

	bl->head = bl->tail = NULL;

	return bio;
	}

	#if defined(CONFIG_BLK_DEV_INTEGRITY)

	#define bip_vec_idx(bip, idx) (&(bip->bip_vec[(idx)]))
	#define bip_vec(bip) bip_vec_idx(bip, 0)

	#define __bip_for_each_vec(bvl, bip, i, start_idx) \
	for (bvl = bip_vec_idx((bip), (start_idx)), i = (start_idx); \
	i < (bip)->bip_vcnt; \
	bvl++, i++)

	#define bip_for_each_vec(bvl, bip, i) \
	__bip_for_each_vec(bvl, bip, i, (bip)->bip_idx)

	#define bio_for_each_integrity_vec(_bvl, _bio, _iter) \
	for_each_bio(_bio) \
	bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)

	#define bio_integrity(bio) (bio->bi_integrity != NULL)

	extern struct bio_integrity_payload bio_integrity_alloc_bioset(struct bio , gfp_t, unsigned int, struct bio_set *);
	extern struct bio_integrity_payload bio_integrity_alloc(struct bio , gfp_t, unsigned int);
	extern void bio_integrity_free(struct bio , struct bio_set );
	extern int bio_integrity_add_page(struct bio , struct page , unsigned int, unsigned int);
	extern int bio_integrity_enabled(struct bio *bio);
	extern int bio_integrity_set_tag(struct bio , void , unsigned int);
	extern int bio_integrity_get_tag(struct bio , void , unsigned int);
	extern int bio_integrity_prep(struct bio *);
	extern void bio_integrity_endio(struct bio *, int);
	extern void bio_integrity_advance(struct bio *, unsigned int);
	extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
	extern void bio_integrity_split(struct bio , struct bio_pair , int);
	extern int bio_integrity_clone(struct bio , struct bio , gfp_t, struct bio_set *);
	extern int bioset_integrity_create(struct bio_set *, int);
	extern void bioset_integrity_free(struct bio_set *);
	extern void bio_integrity_init(void);

	#else /* CONFIG_BLK_DEV_INTEGRITY */

	static inline int bio_integrity(struct bio *bio)
	{
	return 0;
	}

	static inline int bio_integrity_enabled(struct bio *bio)
	{
	return 0;
	}

	static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
	{
	return 0;
	}

	static inline void bioset_integrity_free (struct bio_set *bs)
	{
	return;
	}

	static inline int bio_integrity_prep(struct bio *bio)
	{
	return 0;
	}

	static inline void bio_integrity_free(struct bio bio, struct bio_set bs)
	{
	return;
	}

	static inline int bio_integrity_clone(struct bio bio, struct bio bio_src,
	gfp_t gfp_mask, struct bio_set *bs)
	{
	return 0;
	}

	static inline void bio_integrity_split(struct bio bio, struct bio_pair bp,
	int sectors)
	{
	return;
	}

	static inline void bio_integrity_advance(struct bio *bio,
	unsigned int bytes_done)
	{
	return;
	}

	static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
	unsigned int sectors)
	{
	return;
	}

	static inline void bio_integrity_init(void)
	{
	return;
	}

	#endif /* CONFIG_BLK_DEV_INTEGRITY */

	#endif /* CONFIG_BLOCK */
	#endif /* __LINUX_BIO_H */