/*

 * 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 */