/*
* Copyright (C) 2003 Sistina Software
* Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
*
* Device-Mapper low-level I/O.
*
* This file is released under the GPL.
*/

#ifndef _LINUX_DM_IO_H
#define _LINUX_DM_IO_H

#ifdef __KERNEL__

#include <linux/types.h>

struct dm_io_region {
struct block_device *bdev;
sector_t sector;
sector_t count; /* If this is zero the region is ignored. */
};

struct page_list {
struct page_list *next;
struct page *page;
};

typedef void (*io_notify_fn)(unsigned long error, void *context);

enum dm_io_mem_type {
DM_IO_PAGE_LIST,/* Page list */
DM_IO_BVEC, /* Bio vector */
DM_IO_VMA, /* Virtual memory area */
DM_IO_KMEM, /* Kernel memory */
};

struct dm_io_memory {
enum dm_io_mem_type type;

union {
struct page_list *pl;
struct bio_vec *bvec;
void *vma;
void *addr;
} ptr;

unsigned offset;
};

struct dm_io_notify {
io_notify_fn fn; /* Callback for asynchronous requests */
void *context; /* Passed to callback */
};

/*
* IO request structure
*/
struct dm_io_client;
struct dm_io_request {
int bi_rw; /* READ|WRITE - not READA */
struct dm_io_memory mem; /* Memory to use for io */
struct dm_io_notify notify; /* Synchronous if notify.fn is NULL */
struct dm_io_client *client; /* Client memory handler */
};

/*
* For async io calls, users can alternatively use the dm_io() function below
* and dm_io_client_create() to create private mempools for the client.
*
* Create/destroy may block.
*/
struct dm_io_client *dm_io_client_create(unsigned num_pages);
int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client);
void dm_io_client_destroy(struct dm_io_client *client);

/*
* IO interface using private per-client pools.
* Each bit in the optional 'sync_error_bits' bitset indicates whether an
* error occurred doing io to the corresponding region.
*/
int dm_io(struct dm_io_request *io_req, unsigned num_regions,
struct dm_io_region *region, unsigned long *sync_error_bits);

#endif /* __KERNEL__ */
#endif /* _LINUX_DM_IO_H */

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