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dm-io.h

/*
 * Copyright (C) 2003 Sistina Software
 *
 * This file is released under the GPL.
 */

#ifndef _DM_IO_H
#define _DM_IO_H

#include "dm.h"

struct 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 io_region *region, unsigned long *sync_error_bits);

#endif

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