78 строки
2.0 KiB
C
78 строки
2.0 KiB
C
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/*
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* Copyright (C) 2003 Sistina Software
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*
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* This file is released under the GPL.
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*/
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#ifndef _DM_IO_H
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#define _DM_IO_H
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#include "dm.h"
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/* FIXME make this configurable */
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#define DM_MAX_IO_REGIONS 8
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struct io_region {
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struct block_device *bdev;
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sector_t sector;
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sector_t count;
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};
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struct page_list {
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struct page_list *next;
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struct page *page;
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};
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/*
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* 'error' is a bitset, with each bit indicating whether an error
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* occurred doing io to the corresponding region.
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*/
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typedef void (*io_notify_fn)(unsigned long error, void *context);
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/*
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* Before anyone uses the IO interface they should call
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* dm_io_get(), specifying roughly how many pages they are
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* expecting to perform io on concurrently.
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*
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* This function may block.
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*/
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int dm_io_get(unsigned int num_pages);
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void dm_io_put(unsigned int num_pages);
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/*
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* Synchronous IO.
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*
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* Please ensure that the rw flag in the next two functions is
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* either READ or WRITE, ie. we don't take READA. Any
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* regions with a zero count field will be ignored.
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*/
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int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
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struct page_list *pl, unsigned int offset,
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unsigned long *error_bits);
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int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
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struct bio_vec *bvec, unsigned long *error_bits);
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int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
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void *data, unsigned long *error_bits);
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/*
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* Aynchronous IO.
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*
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* The 'where' array may be safely allocated on the stack since
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* the function takes a copy.
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*/
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int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
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struct page_list *pl, unsigned int offset,
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io_notify_fn fn, void *context);
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int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
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struct bio_vec *bvec, io_notify_fn fn, void *context);
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int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
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void *data, io_notify_fn fn, void *context);
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#endif
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