345 lines
11 KiB
C
345 lines
11 KiB
C
/*
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* 2.5 block I/O model
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*
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* Copyright (C) 2001 Jens Axboe <axboe@suse.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public Licens
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
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*/
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#ifndef __LINUX_BIO_H
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#define __LINUX_BIO_H
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#include <linux/highmem.h>
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#include <linux/mempool.h>
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/* Platforms may set this to teach the BIO layer about IOMMU hardware. */
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#include <asm/io.h>
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#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
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#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
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#define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
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#else
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#define BIOVEC_VIRT_START_SIZE(x) 0
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#define BIOVEC_VIRT_OVERSIZE(x) 0
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#endif
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#ifndef BIO_VMERGE_BOUNDARY
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#define BIO_VMERGE_BOUNDARY 0
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#endif
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#define BIO_DEBUG
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#ifdef BIO_DEBUG
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#define BIO_BUG_ON BUG_ON
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#else
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#define BIO_BUG_ON
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#endif
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#define BIO_MAX_PAGES (256)
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#define BIO_MAX_SIZE (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
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#define BIO_MAX_SECTORS (BIO_MAX_SIZE >> 9)
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/*
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* was unsigned short, but we might as well be ready for > 64kB I/O pages
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*/
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struct bio_vec {
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struct page *bv_page;
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unsigned int bv_len;
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unsigned int bv_offset;
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};
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struct bio_set;
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struct bio;
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typedef int (bio_end_io_t) (struct bio *, unsigned int, int);
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typedef void (bio_destructor_t) (struct bio *);
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/*
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* main unit of I/O for the block layer and lower layers (ie drivers and
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* stacking drivers)
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*/
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struct bio {
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sector_t bi_sector;
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struct bio *bi_next; /* request queue link */
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struct block_device *bi_bdev;
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unsigned long bi_flags; /* status, command, etc */
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unsigned long bi_rw; /* bottom bits READ/WRITE,
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* top bits priority
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*/
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unsigned short bi_vcnt; /* how many bio_vec's */
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unsigned short bi_idx; /* current index into bvl_vec */
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/* Number of segments in this BIO after
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* physical address coalescing is performed.
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*/
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unsigned short bi_phys_segments;
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/* Number of segments after physical and DMA remapping
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* hardware coalescing is performed.
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*/
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unsigned short bi_hw_segments;
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unsigned int bi_size; /* residual I/O count */
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/*
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* To keep track of the max hw size, we account for the
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* sizes of the first and last virtually mergeable segments
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* in this bio
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*/
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unsigned int bi_hw_front_size;
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unsigned int bi_hw_back_size;
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unsigned int bi_max_vecs; /* max bvl_vecs we can hold */
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struct bio_vec *bi_io_vec; /* the actual vec list */
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bio_end_io_t *bi_end_io;
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atomic_t bi_cnt; /* pin count */
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void *bi_private;
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bio_destructor_t *bi_destructor; /* destructor */
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struct bio_set *bi_set; /* memory pools set */
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};
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/*
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* bio flags
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*/
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#define BIO_UPTODATE 0 /* ok after I/O completion */
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#define BIO_RW_BLOCK 1 /* RW_AHEAD set, and read/write would block */
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#define BIO_EOF 2 /* out-out-bounds error */
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#define BIO_SEG_VALID 3 /* nr_hw_seg valid */
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#define BIO_CLONED 4 /* doesn't own data */
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#define BIO_BOUNCED 5 /* bio is a bounce bio */
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#define BIO_USER_MAPPED 6 /* contains user pages */
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#define BIO_EOPNOTSUPP 7 /* not supported */
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#define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
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/*
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* top 4 bits of bio flags indicate the pool this bio came from
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*/
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#define BIO_POOL_BITS (4)
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#define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS)
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#define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET)
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#define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET)
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/*
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* bio bi_rw flags
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*
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* bit 0 -- read (not set) or write (set)
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* bit 1 -- rw-ahead when set
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* bit 2 -- barrier
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* bit 3 -- fail fast, don't want low level driver retries
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* bit 4 -- synchronous I/O hint: the block layer will unplug immediately
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*/
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#define BIO_RW 0
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#define BIO_RW_AHEAD 1
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#define BIO_RW_BARRIER 2
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#define BIO_RW_FAILFAST 3
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#define BIO_RW_SYNC 4
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/*
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* various member access, note that bio_data should of course not be used
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* on highmem page vectors
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*/
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#define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
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#define bio_iovec(bio) bio_iovec_idx((bio), (bio)->bi_idx)
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#define bio_page(bio) bio_iovec((bio))->bv_page
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#define bio_offset(bio) bio_iovec((bio))->bv_offset
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#define bio_segments(bio) ((bio)->bi_vcnt - (bio)->bi_idx)
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#define bio_sectors(bio) ((bio)->bi_size >> 9)
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#define bio_cur_sectors(bio) (bio_iovec(bio)->bv_len >> 9)
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#define bio_data(bio) (page_address(bio_page((bio))) + bio_offset((bio)))
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#define bio_barrier(bio) ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
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#define bio_sync(bio) ((bio)->bi_rw & (1 << BIO_RW_SYNC))
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#define bio_failfast(bio) ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
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#define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
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/*
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* will die
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*/
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#define bio_to_phys(bio) (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
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#define bvec_to_phys(bv) (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
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/*
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* queues that have highmem support enabled may still need to revert to
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* PIO transfers occasionally and thus map high pages temporarily. For
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* permanent PIO fall back, user is probably better off disabling highmem
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* I/O completely on that queue (see ide-dma for example)
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*/
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#define __bio_kmap_atomic(bio, idx, kmtype) \
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(kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) + \
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bio_iovec_idx((bio), (idx))->bv_offset)
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#define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
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/*
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* merge helpers etc
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*/
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#define __BVEC_END(bio) bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
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#define __BVEC_START(bio) bio_iovec_idx((bio), (bio)->bi_idx)
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/*
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* allow arch override, for eg virtualized architectures (put in asm/io.h)
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*/
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#ifndef BIOVEC_PHYS_MERGEABLE
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#define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \
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((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
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#endif
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#define BIOVEC_VIRT_MERGEABLE(vec1, vec2) \
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((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
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#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
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(((addr1) | (mask)) == (((addr2) - 1) | (mask)))
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#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
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__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
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#define BIO_SEG_BOUNDARY(q, b1, b2) \
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BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
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#define bio_io_error(bio, bytes) bio_endio((bio), (bytes), -EIO)
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/*
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* drivers should not use the __ version unless they _really_ want to
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* run through the entire bio and not just pending pieces
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*/
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#define __bio_for_each_segment(bvl, bio, i, start_idx) \
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for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx); \
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i < (bio)->bi_vcnt; \
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bvl++, i++)
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#define bio_for_each_segment(bvl, bio, i) \
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__bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
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/*
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* get a reference to a bio, so it won't disappear. the intended use is
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* something like:
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*
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* bio_get(bio);
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* submit_bio(rw, bio);
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* if (bio->bi_flags ...)
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* do_something
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* bio_put(bio);
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*
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* without the bio_get(), it could potentially complete I/O before submit_bio
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* returns. and then bio would be freed memory when if (bio->bi_flags ...)
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* runs
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*/
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#define bio_get(bio) atomic_inc(&(bio)->bi_cnt)
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/*
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* A bio_pair is used when we need to split a bio.
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* This can only happen for a bio that refers to just one
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* page of data, and in the unusual situation when the
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* page crosses a chunk/device boundary
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*
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* The address of the master bio is stored in bio1.bi_private
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* The address of the pool the pair was allocated from is stored
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* in bio2.bi_private
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*/
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struct bio_pair {
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struct bio bio1, bio2;
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struct bio_vec bv1, bv2;
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atomic_t cnt;
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int error;
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};
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extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
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int first_sectors);
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extern mempool_t *bio_split_pool;
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extern void bio_pair_release(struct bio_pair *dbio);
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extern struct bio_set *bioset_create(int, int, int);
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extern void bioset_free(struct bio_set *);
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extern struct bio *bio_alloc(unsigned int __nocast, int);
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extern struct bio *bio_alloc_bioset(unsigned int __nocast, int, struct bio_set *);
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extern void bio_put(struct bio *);
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extern void bio_endio(struct bio *, unsigned int, int);
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struct request_queue;
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extern int bio_phys_segments(struct request_queue *, struct bio *);
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extern int bio_hw_segments(struct request_queue *, struct bio *);
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extern void __bio_clone(struct bio *, struct bio *);
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extern struct bio *bio_clone(struct bio *, unsigned int __nocast);
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extern void bio_init(struct bio *);
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extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
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extern int bio_get_nr_vecs(struct block_device *);
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extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
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unsigned long, unsigned int, int);
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struct sg_iovec;
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extern struct bio *bio_map_user_iov(struct request_queue *,
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struct block_device *,
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struct sg_iovec *, int, int);
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extern void bio_unmap_user(struct bio *);
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extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
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unsigned int);
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extern void bio_set_pages_dirty(struct bio *bio);
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extern void bio_check_pages_dirty(struct bio *bio);
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extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);
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extern int bio_uncopy_user(struct bio *);
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void zero_fill_bio(struct bio *bio);
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#ifdef CONFIG_HIGHMEM
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/*
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* remember to add offset! and never ever reenable interrupts between a
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* bvec_kmap_irq and bvec_kunmap_irq!!
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*
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* This function MUST be inlined - it plays with the CPU interrupt flags.
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* Hence the `extern inline'.
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*/
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extern inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
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{
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unsigned long addr;
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/*
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* might not be a highmem page, but the preempt/irq count
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* balancing is a lot nicer this way
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*/
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local_irq_save(*flags);
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addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
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BUG_ON(addr & ~PAGE_MASK);
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return (char *) addr + bvec->bv_offset;
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}
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extern inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
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{
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unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
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kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
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local_irq_restore(*flags);
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}
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#else
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#define bvec_kmap_irq(bvec, flags) (page_address((bvec)->bv_page) + (bvec)->bv_offset)
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#define bvec_kunmap_irq(buf, flags) do { *(flags) = 0; } while (0)
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#endif
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extern inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
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unsigned long *flags)
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{
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return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
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}
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#define __bio_kunmap_irq(buf, flags) bvec_kunmap_irq(buf, flags)
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#define bio_kmap_irq(bio, flags) \
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__bio_kmap_irq((bio), (bio)->bi_idx, (flags))
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#define bio_kunmap_irq(buf,flags) __bio_kunmap_irq(buf, flags)
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#endif /* __LINUX_BIO_H */
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