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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"
#include <linux/list.h>
/* Move these to bitops.h eventually */
/* Improved generic_fls algorithm (in 2.4 there is no generic_fls so far) */
/* (c) 2002, D.Phillips and Sistina Software */
/* Licensed under Version 2 of the GPL */
static unsigned generic_fls8(unsigned n)
{
return n & 0xf0 ?
n & 0xc0 ? (n >> 7) + 7 : (n >> 5) + 5:
n & 0x0c ? (n >> 3) + 3 : n - ((n + 1) >> 2);
}
static inline unsigned generic_fls16(unsigned n)
{
return n & 0xff00? generic_fls8(n >> 8) + 8 : generic_fls8(n);
}
static inline unsigned generic_fls32(unsigned n)
{
return n & 0xffff0000 ? generic_fls16(n >> 16) + 16 : generic_fls16(n);
}
/* FIXME make this configurable */
#define DM_MAX_IO_REGIONS 8
struct io_region {
kdev_t dev;
sector_t sector;
sector_t count;
};
/*
* 'error' is a bitset, with each bit indicating whether an error
* occurred doing io to the corresponding region.
*/
typedef void (*io_notify_fn)(unsigned int 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 *pages, unsigned int offset,
unsigned int *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 *pages, unsigned int offset,
io_notify_fn fn, void *context);
#endif
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