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/*

 * 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>

/* Platforms may set this to teach the BIO layer about IOMMU hardware. */

#include <asm/io.h>

#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;

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 */

        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 */

};

/*

 * 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_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

 */

#define BIO_RW          0

#define BIO_RW_AHEAD    1

#define BIO_RW_BARRIER  2

#define BIO_RW_FAILFAST 3

/*

 * 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))

/*

 * 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), 0)

#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \

        ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))

#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 *bio_alloc(int, int);

extern void bio_put(struct bio *);

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

struct request_queue;

extern inline int bio_phys_segments(struct request_queue *, struct bio *);

extern inline int bio_hw_segments(struct request_queue *, struct bio *);

extern inline void __bio_clone(struct bio *, struct bio *);

extern struct bio *bio_clone(struct bio *, int);

extern inline 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 block_device *, unsigned long,

                                unsigned int, int);

extern void bio_unmap_user(struct bio *, int);

extern void bio_set_pages_dirty(struct bio *bio);

extern void bio_check_pages_dirty(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);

        if (addr & ~PAGE_MASK)

                BUG();

        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 */