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linux-2.6/include/linux/bio.h
Chen, Kenneth W e61c90188b [PATCH] optimize o_direct on block devices 
Implement block device specific .direct_IO method instead of going through
generic direct_io_worker for block device.

direct_io_worker() is fairly complex because it needs to handle O_DIRECT on
file system, where it needs to perform block allocation, hole detection,
extents file on write, and tons of other corner cases.  The end result is
that it takes tons of CPU time to submit an I/O.

For block device, the block allocation is much simpler and a tight triple
loop can be written to iterate each iovec and each page within the iovec in
order to construct/prepare bio structure and then subsequently submit it to
the block layer.  This significantly speeds up O_D on block device.

[akpm@osdl.org: small speedup]
Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13 09:05:50 -08:00

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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>
#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; /* 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 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 */
};
/*
* 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
#define BIO_RW_META 5
/*
* 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))
#define bio_rw_meta(bio) ((bio)->bi_rw & (1 << BIO_RW_META))
/*
* 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(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 *, 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 *, 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 struct bio *bio_map_user(struct request_queue *, struct block_device *,
unsigned long, unsigned int, int);
struct sg_iovec;
extern struct bio *bio_map_user_iov(struct request_queue *,
struct block_device *,
struct sg_iovec *, int, int);
extern void bio_unmap_user(struct bio *);
extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
gfp_t);
extern void bio_set_pages_dirty(struct bio *bio);
extern void bio_check_pages_dirty(struct bio *bio);
extern void bio_release_pages(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.
*/
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, KM_BIO_SRC_IRQ);
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, 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)
#endif /* __LINUX_BIO_H */
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