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[linux-rt-nao.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>

#ifdef CONFIG_BLOCK

#include <asm/io.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)

/*
 * 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;
struct bio_integrity_payload;
typedef void (bio_end_io_t) (struct bio *, 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;      /* device address in 512 byte
                                                   sectors */
        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 int            bi_phys_segments;

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

        /*
         * To keep track of the max segment size, we account for the
         * sizes of the first and last mergeable segments in this bio.
         */
        unsigned int            bi_seg_front_size;
        unsigned int            bi_seg_back_size;

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

        unsigned int            bi_comp_cpu;    /* completion CPU */

        atomic_t                bi_cnt;         /* pin count */

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

        bio_end_io_t            *bi_end_io;

        void                    *bi_private;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
        struct bio_integrity_payload *bi_integrity;  /* data integrity */
#endif

        bio_destructor_t        *bi_destructor; /* destructor */

        /*
         * We can inline a number of vecs at the end of the bio, to avoid
         * double allocations for a small number of bio_vecs. This member
         * MUST obviously be kept at the very end of the bio.
         */
        struct bio_vec          bi_inline_vecs[0];
};

/*
 * 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       /* bi_phys_segments 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_CPU_AFFINE  8       /* complete bio on same CPU as submitted */
#define BIO_NULL_MAPPED 9       /* contains invalid user pages */
#define BIO_FS_INTEGRITY 10     /* fs owns integrity data, not block layer */
#define BIO_QUIET       11      /* Make BIO Quiet */
#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 -- data direction
 *      If not set, bio is a read from device. If set, it's a write to device.
 * bit 1 -- rw-ahead when set
 * bit 2 -- barrier
 *      Insert a serialization point in the IO queue, forcing previously
 *      submitted IO to be completed before this one is issued.
 * bit 3 -- synchronous I/O hint: the block layer will unplug immediately
 *      Note that this does NOT indicate that the IO itself is sync, just
 *      that the block layer will not postpone issue of this IO by plugging.
 * bit 4 -- metadata request
 *      Used for tracing to differentiate metadata and data IO. May also
 *      get some preferential treatment in the IO scheduler
 * bit 5 -- discard sectors
 *      Informs the lower level device that this range of sectors is no longer
 *      used by the file system and may thus be freed by the device. Used
 *      for flash based storage.
 * bit 6 -- fail fast device errors
 * bit 7 -- fail fast transport errors
 * bit 8 -- fail fast driver errors
 *      Don't want driver retries for any fast fail whatever the reason.
 */
#define BIO_RW          0       /* Must match RW in req flags (blkdev.h) */
#define BIO_RW_AHEAD    1       /* Must match FAILFAST in req flags */
#define BIO_RW_BARRIER  2
#define BIO_RW_SYNCIO   3
#define BIO_RW_UNPLUG   4
#define BIO_RW_META     5
#define BIO_RW_DISCARD  6
#define BIO_RW_FAILFAST_DEV             7
#define BIO_RW_FAILFAST_TRANSPORT       8
#define BIO_RW_FAILFAST_DRIVER          9

#define bio_rw_flagged(bio, flag)       ((bio)->bi_rw & (1 << (flag)))

/*
 * Old defines, these should eventually be replaced by direct usage of
 * bio_rw_flagged()
 */
#define bio_barrier(bio)        bio_rw_flagged(bio, BIO_RW_BARRIER)
#define bio_sync(bio)           bio_rw_flagged(bio, BIO_RW_SYNCIO)
#define bio_unplug(bio)         bio_rw_flagged(bio, BIO_RW_UNPLUG)
#define bio_failfast_dev(bio)   bio_rw_flagged(bio, BIO_RW_FAILFAST_DEV)
#define bio_failfast_transport(bio)     \
                bio_rw_flagged(bio, BIO_RW_FAILFAST_TRANSPORT)
#define bio_failfast_driver(bio)        \
                bio_rw_flagged(bio, BIO_RW_FAILFAST_DRIVER)
#define bio_rw_ahead(bio)       bio_rw_flagged(bio, BIO_RW_AHEAD)
#define bio_rw_meta(bio)        bio_rw_flagged(bio, BIO_RW_META)
#define bio_discard(bio)        bio_rw_flagged(bio, BIO_RW_DISCARD)

/*
 * 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_empty_barrier(bio)  (bio_barrier(bio) && !bio_has_data(bio) && !bio_discard(bio))

static inline unsigned int bio_cur_sectors(struct bio *bio)
{
        if (bio->bi_vcnt)
                return bio_iovec(bio)->bv_len >> 9;
        else /* dataless requests such as discard */
                return bio->bi_size >> 9;
}

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, 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)

/* 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, (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) 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 */
        struct bio_vec          *bip_vec;       /* integrity data vector */

        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_pool;       /* pool the ivec 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 */
};
#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, int);
extern struct bio *bio_kmalloc(gfp_t, 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);
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);

/*
 * Allow queuer to specify a completion CPU for this bio
 */
static inline void bio_set_completion_cpu(struct bio *bio, unsigned int cpu)
{
        bio->bi_comp_cpu = cpu;
}

/*
 * 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;
extern struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly;

/*
 * 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!
 *
 * This function MUST be inlined - it plays with the CPU interrupt flags.
 */
static __always_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;
}

static __always_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

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;
}

#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_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_slab(void);

#else /* CONFIG_BLK_DEV_INTEGRITY */

#define bio_integrity(a)                (0)
#define bioset_integrity_create(a, b)   (0)
#define bio_integrity_prep(a)           (0)
#define bio_integrity_enabled(a)        (0)
#define bio_integrity_clone(a, b, c,d ) (0)
#define bioset_integrity_free(a)        do { } while (0)
#define bio_integrity_free(a, b)        do { } while (0)
#define bio_integrity_endio(a, b)       do { } while (0)
#define bio_integrity_advance(a, b)     do { } while (0)
#define bio_integrity_trim(a, b, c)     do { } while (0)
#define bio_integrity_split(a, b, c)    do { } while (0)
#define bio_integrity_set_tag(a, b, c)  do { } while (0)
#define bio_integrity_get_tag(a, b, c)  do { } while (0)
#define bio_integrity_init_slab(a)      do { } while (0)

#endif /* CONFIG_BLK_DEV_INTEGRITY */

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