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