[deliverable/linux.git] / include / 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>

/* Platforms may set this to teach the BIO layer about IOMMU hardware. */
#include <asm/io.h>

#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
#define BIOVEC_VIRT_OVERSIZE(x)	((x) > BIO_VMERGE_MAX_SIZE)
#else
#define BIOVEC_VIRT_START_SIZE(x)	0
#define BIOVEC_VIRT_OVERSIZE(x)		0
#endif

#ifndef BIO_VMERGE_BOUNDARY
#define BIO_VMERGE_BOUNDARY	0
#endif

#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)

/*
 * was unsigned short, but we might as well be ready for > 64kB I/O pages
 */
struct bio_vec {
	struct page	*bv_page;
	unsigned int	bv_len;
	unsigned int	bv_offset;
};

struct bio_set;
struct bio;
typedef int (bio_end_io_t) (struct bio *, unsigned int, int);
typedef void (bio_destructor_t) (struct bio *);

/*
 * main unit of I/O for the block layer and lower layers (ie drivers and
 * stacking drivers)
 */
struct bio {
	sector_t		bi_sector;
	struct bio		*bi_next;	/* request queue link */
	struct block_device	*bi_bdev;
	unsigned long		bi_flags;	/* status, command, etc */
	unsigned long		bi_rw;		/* bottom bits READ/WRITE,
						 * top bits priority
						 */

	unsigned short		bi_vcnt;	/* how many bio_vec's */
	unsigned short		bi_idx;		/* current index into bvl_vec */

	/* Number of segments in this BIO after
	 * physical address coalescing is performed.
	 */
	unsigned short		bi_phys_segments;

	/* Number of segments after physical and DMA remapping
	 * hardware coalescing is performed.
	 */
	unsigned short		bi_hw_segments;

	unsigned int		bi_size;	/* residual I/O count */

	/*
	 * To keep track of the max hw size, we account for the
	 * sizes of the first and last virtually mergeable segments
	 * in this bio
	 */
	unsigned int		bi_hw_front_size;
	unsigned int		bi_hw_back_size;

	unsigned int		bi_max_vecs;	/* max bvl_vecs we can hold */

	struct bio_vec		*bi_io_vec;	/* the actual vec list */

	bio_end_io_t		*bi_end_io;
	atomic_t		bi_cnt;		/* pin count */

	void			*bi_private;

	bio_destructor_t	*bi_destructor;	/* destructor */
	struct bio_set		*bi_set;	/* memory pools set */
};

/*
 * bio flags
 */
#define BIO_UPTODATE	0	/* ok after I/O completion */
#define BIO_RW_BLOCK	1	/* RW_AHEAD set, and read/write would block */
#define BIO_EOF		2	/* out-out-bounds error */
#define BIO_SEG_VALID	3	/* nr_hw_seg valid */
#define BIO_CLONED	4	/* doesn't own data */
#define BIO_BOUNCED	5	/* bio is a bounce bio */
#define BIO_USER_MAPPED 6	/* contains user pages */
#define BIO_EOPNOTSUPP	7	/* not supported */
#define bio_flagged(bio, flag)	((bio)->bi_flags & (1 << (flag)))

/*
 * top 4 bits of bio flags indicate the pool this bio came from
 */
#define BIO_POOL_BITS		(4)
#define BIO_POOL_OFFSET		(BITS_PER_LONG - BIO_POOL_BITS)
#define BIO_POOL_MASK		(1UL << BIO_POOL_OFFSET)
#define BIO_POOL_IDX(bio)	((bio)->bi_flags >> BIO_POOL_OFFSET)	

/*
 * bio bi_rw flags
 *
 * bit 0 -- read (not set) or write (set)
 * bit 1 -- rw-ahead when set
 * bit 2 -- barrier
 * bit 3 -- fail fast, don't want low level driver retries
 * bit 4 -- synchronous I/O hint: the block layer will unplug immediately
 */
#define BIO_RW		0
#define BIO_RW_AHEAD	1
#define BIO_RW_BARRIER	2
#define BIO_RW_FAILFAST	3
#define BIO_RW_SYNC	4

/*
 * 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)
#define bio_cur_sectors(bio)	(bio_iovec(bio)->bv_len >> 9)
#define bio_data(bio)		(page_address(bio_page((bio))) + bio_offset((bio)))
#define bio_barrier(bio)	((bio)->bi_rw & (1 << BIO_RW_BARRIER))
#define bio_sync(bio)		((bio)->bi_rw & (1 << BIO_RW_SYNC))
#define bio_failfast(bio)	((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
#define bio_rw_ahead(bio)	((bio)->bi_rw & (1 << BIO_RW_AHEAD))

/*
 * 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, kmtype) +	\
		bio_iovec_idx((bio), (idx))->bv_offset)

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

/*
 * 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)

/*
 * allow arch override, for eg virtualized architectures (put in asm/io.h)
 */
#ifndef BIOVEC_PHYS_MERGEABLE
#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
	((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
#endif

#define BIOVEC_VIRT_MERGEABLE(vec1, vec2)	\
	((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
#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, (q)->seg_boundary_mask)
#define BIO_SEG_BOUNDARY(q, b1, b2) \
	BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))

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


/*
 * 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;
	atomic_t	cnt;
	int		error;
};
extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
				  int first_sectors);
extern mempool_t *bio_split_pool;
extern void bio_pair_release(struct bio_pair *dbio);

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

extern struct bio *bio_alloc(unsigned int __nocast, int);
extern struct bio *bio_alloc_bioset(unsigned int __nocast, int, struct bio_set *);
extern void bio_put(struct bio *);

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

extern void __bio_clone(struct bio *, struct bio *);
extern struct bio *bio_clone(struct bio *, unsigned int __nocast);

extern void bio_init(struct bio *);

extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
extern int bio_get_nr_vecs(struct block_device *);
extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
				unsigned long, unsigned int, int);
extern void bio_unmap_user(struct bio *);
extern void bio_set_pages_dirty(struct bio *bio);
extern void bio_check_pages_dirty(struct bio *bio);
extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);
extern int bio_uncopy_user(struct bio *);
void zero_fill_bio(struct bio *bio);

#ifdef CONFIG_HIGHMEM
/*
 * remember to add offset! and never ever reenable interrupts between a
 * bvec_kmap_irq and bvec_kunmap_irq!!
 *
 * This function MUST be inlined - it plays with the CPU interrupt flags.
 * Hence the `extern inline'.
 */
extern 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, KM_BIO_SRC_IRQ);

	BUG_ON(addr & ~PAGE_MASK);

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

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

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

#else
#define bvec_kmap_irq(bvec, flags)	(page_address((bvec)->bv_page) + (bvec)->bv_offset)
#define bvec_kunmap_irq(buf, flags)	do { *(flags) = 0; } while (0)
#endif

extern 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)

#endif /* __LINUX_BIO_H */
Commit	Line	Data
1da177e4 LT	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>
22e2c507	25	#include <linux/ioprio.h>
1da177e4 LT	26
	27	/* Platforms may set this to teach the BIO layer about IOMMU hardware. */
	28	#include <asm/io.h>
	29
	30	#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
	31	#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
	32	#define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
	33	#else
	34	#define BIOVEC_VIRT_START_SIZE(x) 0
	35	#define BIOVEC_VIRT_OVERSIZE(x) 0
	36	#endif
	37
	38	#ifndef BIO_VMERGE_BOUNDARY
	39	#define BIO_VMERGE_BOUNDARY 0
	40	#endif
	41
	42	#define BIO_DEBUG
	43
	44	#ifdef BIO_DEBUG
	45	#define BIO_BUG_ON BUG_ON
	46	#else
	47	#define BIO_BUG_ON
	48	#endif
	49
	50	#define BIO_MAX_PAGES (256)
	51	#define BIO_MAX_SIZE (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
	52	#define BIO_MAX_SECTORS (BIO_MAX_SIZE >> 9)
	53
	54	/*
	55	* was unsigned short, but we might as well be ready for > 64kB I/O pages
	56	*/
	57	struct bio_vec {
	58	struct page *bv_page;
	59	unsigned int bv_len;
	60	unsigned int bv_offset;
	61	};
	62
	63	struct bio_set;
	64	struct bio;
	65	typedef int (bio_end_io_t) (struct bio *, unsigned int, int);
	66	typedef void (bio_destructor_t) (struct bio *);
	67
	68	/*
	69	* main unit of I/O for the block layer and lower layers (ie drivers and
	70	* stacking drivers)
	71	*/
	72	struct bio {
	73	sector_t bi_sector;
	74	struct bio bi_next; / request queue link */
	75	struct block_device *bi_bdev;
	76	unsigned long bi_flags; /* status, command, etc */
	77	unsigned long bi_rw; /* bottom bits READ/WRITE,
	78	* top bits priority
	79	*/
	80
	81	unsigned short bi_vcnt; /* how many bio_vec's */
	82	unsigned short bi_idx; /* current index into bvl_vec */
	83
	84	/* Number of segments in this BIO after
	85	* physical address coalescing is performed.
	86	*/
	87	unsigned short bi_phys_segments;
	88
	89	/* Number of segments after physical and DMA remapping
90	* hardware coalescing is performed.
91	*/
92	unsigned short bi_hw_segments;
93
94	unsigned int bi_size; /* residual I/O count */
95
96	/*
97	* To keep track of the max hw size, we account for the
98	* sizes of the first and last virtually mergeable segments
99	* in this bio
100	*/
101	unsigned int bi_hw_front_size;
102	unsigned int bi_hw_back_size;
103
104	unsigned int bi_max_vecs; /* max bvl_vecs we can hold */
105
106	struct bio_vec bi_io_vec; / the actual vec list */
107
108	bio_end_io_t *bi_end_io;
109	atomic_t bi_cnt; /* pin count */
110
111	void *bi_private;
112
113	bio_destructor_t bi_destructor; / destructor */
114	struct bio_set bi_set; / memory pools set */
115	};
116
117	/*
118	* bio flags
119	*/
120	#define BIO_UPTODATE 0 /* ok after I/O completion */
121	#define BIO_RW_BLOCK 1 /* RW_AHEAD set, and read/write would block */
122	#define BIO_EOF 2 /* out-out-bounds error */
123	#define BIO_SEG_VALID 3 /* nr_hw_seg valid */
124	#define BIO_CLONED 4 /* doesn't own data */
125	#define BIO_BOUNCED 5 /* bio is a bounce bio */
126	#define BIO_USER_MAPPED 6 /* contains user pages */
127	#define BIO_EOPNOTSUPP 7 /* not supported */
128	#define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
129
130	/*
131	* top 4 bits of bio flags indicate the pool this bio came from
132	*/
133	#define BIO_POOL_BITS (4)
134	#define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS)
135	#define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET)
136	#define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET)
137
138	/*
139	* bio bi_rw flags
140	*
141	* bit 0 -- read (not set) or write (set)
142	* bit 1 -- rw-ahead when set
143	* bit 2 -- barrier
144	* bit 3 -- fail fast, don't want low level driver retries
145	* bit 4 -- synchronous I/O hint: the block layer will unplug immediately
146	*/
147	#define BIO_RW 0
148	#define BIO_RW_AHEAD 1
149	#define BIO_RW_BARRIER 2
150	#define BIO_RW_FAILFAST 3
151	#define BIO_RW_SYNC 4
152
22e2c507 JA	153	/*
	154	* upper 16 bits of bi_rw define the io priority of this bio
	155	*/
	156	#define BIO_PRIO_SHIFT (8 * sizeof(unsigned long) - IOPRIO_BITS)
	157	#define bio_prio(bio) ((bio)->bi_rw >> BIO_PRIO_SHIFT)
	158	#define bio_prio_valid(bio) ioprio_valid(bio_prio(bio))
	159
	160	#define bio_set_prio(bio, prio) do { \
	161	WARN_ON(prio >= (1 << IOPRIO_BITS)); \
	162	(bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1); \
	163	(bio)->bi_rw \|= ((unsigned long) (prio) << BIO_PRIO_SHIFT); \
	164	} while (0)
	165
1da177e4 LT	166	/*
	167	* various member access, note that bio_data should of course not be used
	168	* on highmem page vectors
	169	*/
	170	#define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
	171	#define bio_iovec(bio) bio_iovec_idx((bio), (bio)->bi_idx)
	172	#define bio_page(bio) bio_iovec((bio))->bv_page
	173	#define bio_offset(bio) bio_iovec((bio))->bv_offset
	174	#define bio_segments(bio) ((bio)->bi_vcnt - (bio)->bi_idx)
	175	#define bio_sectors(bio) ((bio)->bi_size >> 9)
	176	#define bio_cur_sectors(bio) (bio_iovec(bio)->bv_len >> 9)
	177	#define bio_data(bio) (page_address(bio_page((bio))) + bio_offset((bio)))
	178	#define bio_barrier(bio) ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
	179	#define bio_sync(bio) ((bio)->bi_rw & (1 << BIO_RW_SYNC))
	180	#define bio_failfast(bio) ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
	181	#define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
	182
	183	/*
	184	* will die
	185	*/
	186	#define bio_to_phys(bio) (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
	187	#define bvec_to_phys(bv) (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
	188
	189	/*
	190	* queues that have highmem support enabled may still need to revert to
	191	* PIO transfers occasionally and thus map high pages temporarily. For
	192	* permanent PIO fall back, user is probably better off disabling highmem
	193	* I/O completely on that queue (see ide-dma for example)
	194	*/
	195	#define __bio_kmap_atomic(bio, idx, kmtype) \
	196	(kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) + \
	197	bio_iovec_idx((bio), (idx))->bv_offset)
	198
	199	#define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
	200
	201	/*
	202	* merge helpers etc
	203	*/
	204
	205	#define __BVEC_END(bio) bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
	206	#define __BVEC_START(bio) bio_iovec_idx((bio), (bio)->bi_idx)
	207
	208	/*
	209	* allow arch override, for eg virtualized architectures (put in asm/io.h)
	210	*/
	211	#ifndef BIOVEC_PHYS_MERGEABLE
	212	#define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \
	213	((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
	214	#endif
	215
	216	#define BIOVEC_VIRT_MERGEABLE(vec1, vec2) \
	217	((((bvec_to_phys((vec1)) + (vec1)->bv_len) \| bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
	218	#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
	219	(((addr1) \| (mask)) == (((addr2) - 1) \| (mask)))
	220	#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
	221	__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
	222	#define BIO_SEG_BOUNDARY(q, b1, b2) \
	223	BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
	224
	225	#define bio_io_error(bio, bytes) bio_endio((bio), (bytes), -EIO)
	226
	227	/*
	228	* drivers should not use the __ version unless they _really_ want to
	229	* run through the entire bio and not just pending pieces
230	*/
231	#define __bio_for_each_segment(bvl, bio, i, start_idx) \
232	for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx); \
233	i < (bio)->bi_vcnt; \
234	bvl++, i++)
235
236	#define bio_for_each_segment(bvl, bio, i) \
237	__bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
238
239	/*
240	* get a reference to a bio, so it won't disappear. the intended use is
241	* something like:
242	*
243	* bio_get(bio);
244	* submit_bio(rw, bio);
245	* if (bio->bi_flags ...)
246	* do_something
247	* bio_put(bio);
248	*
249	* without the bio_get(), it could potentially complete I/O before submit_bio
250	* returns. and then bio would be freed memory when if (bio->bi_flags ...)
251	* runs
252	*/
253	#define bio_get(bio) atomic_inc(&(bio)->bi_cnt)
254
255
256	/*
257	* A bio_pair is used when we need to split a bio.
258	* This can only happen for a bio that refers to just one
259	* page of data, and in the unusual situation when the
260	* page crosses a chunk/device boundary
261	*
262	* The address of the master bio is stored in bio1.bi_private
263	* The address of the pool the pair was allocated from is stored
264	* in bio2.bi_private
265	*/
266	struct bio_pair {
267	struct bio bio1, bio2;
268	struct bio_vec bv1, bv2;
269	atomic_t cnt;
270	int error;
271	};
272	extern struct bio_pair bio_split(struct bio bi, mempool_t *pool,
273	int first_sectors);
274	extern mempool_t *bio_split_pool;
275	extern void bio_pair_release(struct bio_pair *dbio);
276
277	extern struct bio_set *bioset_create(int, int, int);
278	extern void bioset_free(struct bio_set *);
279
280	extern struct bio *bio_alloc(unsigned int __nocast, int);
281	extern struct bio bio_alloc_bioset(unsigned int __nocast, int, struct bio_set );
282	extern void bio_put(struct bio *);
283
284	extern void bio_endio(struct bio *, unsigned int, int);
285	struct request_queue;
286	extern int bio_phys_segments(struct request_queue , struct bio );
287	extern int bio_hw_segments(struct request_queue , struct bio );
288
289	extern void __bio_clone(struct bio , struct bio );
290	extern struct bio bio_clone(struct bio , unsigned int __nocast);
291
292	extern void bio_init(struct bio *);
293
294	extern int bio_add_page(struct bio , struct page , unsigned int,unsigned int);
295	extern int bio_get_nr_vecs(struct block_device *);
296	extern struct bio bio_map_user(struct request_queue , struct block_device *,
297	unsigned long, unsigned int, int);
298	extern void bio_unmap_user(struct bio *);
299	extern void bio_set_pages_dirty(struct bio *bio);
300	extern void bio_check_pages_dirty(struct bio *bio);
301	extern struct bio bio_copy_user(struct request_queue , unsigned long, unsigned int, int);
302	extern int bio_uncopy_user(struct bio *);
303	void zero_fill_bio(struct bio *bio);
304
305	#ifdef CONFIG_HIGHMEM
306	/*
307	* remember to add offset! and never ever reenable interrupts between a
308	* bvec_kmap_irq and bvec_kunmap_irq!!
309	*
310	* This function MUST be inlined - it plays with the CPU interrupt flags.
311	* Hence the `extern inline'.
312	*/
313	extern inline char bvec_kmap_irq(struct bio_vec bvec, unsigned long *flags)
314	{
315	unsigned long addr;
316
317	/*
318	* might not be a highmem page, but the preempt/irq count
319	* balancing is a lot nicer this way
320	*/
321	local_irq_save(*flags);
322	addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
323
324	BUG_ON(addr & ~PAGE_MASK);
325
326	return (char *) addr + bvec->bv_offset;
327	}
328
329	extern inline void bvec_kunmap_irq(char buffer, unsigned long flags)
330	{
331	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
332
333	kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
334	local_irq_restore(*flags);
335	}
336
337	#else
338	#define bvec_kmap_irq(bvec, flags) (page_address((bvec)->bv_page) + (bvec)->bv_offset)
339	#define bvec_kunmap_irq(buf, flags) do { *(flags) = 0; } while (0)
340	#endif
341
342	extern inline char __bio_kmap_irq(struct bio bio, unsigned short idx,
343	unsigned long *flags)
344	{
345	return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
346	}
347	#define __bio_kunmap_irq(buf, flags) bvec_kunmap_irq(buf, flags)
348
349	#define bio_kmap_irq(bio, flags) \
350	__bio_kmap_irq((bio), (bio)->bi_idx, (flags))
351	#define bio_kunmap_irq(buf,flags) __bio_kunmap_irq(buf, flags)
352
353	#endif /* __LINUX_BIO_H */