/*
   * Copyright (C) 2001 Sistina Software (UK) Limited.
   * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
   *
   * This file is released under the LGPL.
   */
  
  #ifndef _LINUX_DEVICE_MAPPER_H
  #define _LINUX_DEVICE_MAPPER_H

  #ifdef __KERNEL__

  struct dm_target;
  struct dm_table;
  struct dm_dev;

  struct mapped_device;

  
  typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  
  union map_info {
  	void *ptr;
  	unsigned long long ll;
  };
  
  /*
   * In the constructor the target parameter will already have the
   * table, type, begin and len fields filled in.
   */
  typedef int (*dm_ctr_fn) (struct dm_target *target,
  			  unsigned int argc, char **argv);
  
  /*
   * The destructor doesn't need to free the dm_target, just
   * anything hidden ti->private.
   */
  typedef void (*dm_dtr_fn) (struct dm_target *ti);
  
  /*
   * The map function must return:
   * < 0: error
   * = 0: The target will handle the io by resubmitting it later

   * = 1: simple remap complete

   * = 2: The target wants to push back the io

   */
  typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  			  union map_info *map_context);
  
  /*
   * Returns:
   * < 0 : error (currently ignored)
   * 0   : ended successfully
   * 1   : for some reason the io has still not completed (eg,
   *       multipath target might want to requeue a failed io).

   * 2   : The target wants to push back the io

   */
  typedef int (*dm_endio_fn) (struct dm_target *ti,
  			    struct bio *bio, int error,
  			    union map_info *map_context);

  typedef void (*dm_flush_fn) (struct dm_target *ti);

  typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  typedef void (*dm_postsuspend_fn) (struct dm_target *ti);

  typedef int (*dm_preresume_fn) (struct dm_target *ti);

  typedef void (*dm_resume_fn) (struct dm_target *ti);
  
  typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  			     char *result, unsigned int maxlen);
  
  typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);

  typedef int (*dm_ioctl_fn) (struct dm_target *ti, struct inode *inode,
  			    struct file *filp, unsigned int cmd,
  			    unsigned long arg);

  void dm_error(const char *message);
  
  /*

   * Combine device limits.
   */
  void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev);
  
  /*

   * Constructors should call these functions to ensure destination devices
   * are opened/closed correctly.
   * FIXME: too many arguments.
   */
  int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
  		  sector_t len, int mode, struct dm_dev **result);
  void dm_put_device(struct dm_target *ti, struct dm_dev *d);
  
  /*
   * Information about a target type
   */
  struct target_type {
  	const char *name;
  	struct module *module;

  	unsigned version[3];

  	dm_ctr_fn ctr;
  	dm_dtr_fn dtr;
  	dm_map_fn map;
  	dm_endio_fn end_io;

  	dm_flush_fn flush;

  	dm_presuspend_fn presuspend;
  	dm_postsuspend_fn postsuspend;

  	dm_preresume_fn preresume;

  	dm_resume_fn resume;
  	dm_status_fn status;
  	dm_message_fn message;

  	dm_ioctl_fn ioctl;

  };
  
  struct io_restrictions {

  	unsigned int		max_sectors;

  	unsigned short		max_phys_segments;
  	unsigned short		max_hw_segments;
  	unsigned short		hardsect_size;
  	unsigned int		max_segment_size;
  	unsigned long		seg_boundary_mask;

  	unsigned char		no_cluster; /* inverted so that 0 is default */

  };
  
  struct dm_target {
  	struct dm_table *table;
  	struct target_type *type;
  
  	/* target limits */
  	sector_t begin;
  	sector_t len;
  
  	/* FIXME: turn this into a mask, and merge with io_restrictions */
  	/* Always a power of 2 */
  	sector_t split_io;
  
  	/*
  	 * These are automatically filled in by
  	 * dm_table_get_device.
  	 */
  	struct io_restrictions limits;
  
  	/* target specific data */
  	void *private;
  
  	/* Used to provide an error string from the ctr */
  	char *error;
  };
  
  int dm_register_target(struct target_type *t);
  int dm_unregister_target(struct target_type *t);

  
  /*-----------------------------------------------------------------
   * Functions for creating and manipulating mapped devices.
   * Drop the reference with dm_put when you finish with the object.
   *---------------------------------------------------------------*/
  
  /*
   * DM_ANY_MINOR chooses the next available minor number.
   */
  #define DM_ANY_MINOR (-1)
  int dm_create(int minor, struct mapped_device **md);
  
  /*
   * Reference counting for md.
   */
  struct mapped_device *dm_get_md(dev_t dev);
  void dm_get(struct mapped_device *md);
  void dm_put(struct mapped_device *md);
  
  /*
   * An arbitrary pointer may be stored alongside a mapped device.
   */
  void dm_set_mdptr(struct mapped_device *md, void *ptr);
  void *dm_get_mdptr(struct mapped_device *md);
  
  /*
   * A device can still be used while suspended, but I/O is deferred.
   */

  int dm_suspend(struct mapped_device *md, unsigned suspend_flags);

  int dm_resume(struct mapped_device *md);
  
  /*
   * Event functions.
   */
  uint32_t dm_get_event_nr(struct mapped_device *md);
  int dm_wait_event(struct mapped_device *md, int event_nr);
  
  /*
   * Info functions.
   */

  const char *dm_device_name(struct mapped_device *md);

  struct gendisk *dm_disk(struct mapped_device *md);
  int dm_suspended(struct mapped_device *md);

  int dm_noflush_suspending(struct dm_target *ti);

  
  /*
   * Geometry functions.
   */
  int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
  int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
  
  
  /*-----------------------------------------------------------------
   * Functions for manipulating device-mapper tables.
   *---------------------------------------------------------------*/
  
  /*
   * First create an empty table.
   */
  int dm_table_create(struct dm_table **result, int mode,
  		    unsigned num_targets, struct mapped_device *md);
  
  /*
   * Then call this once for each target.
   */
  int dm_table_add_target(struct dm_table *t, const char *type,
  			sector_t start, sector_t len, char *params);
  
  /*
   * Finally call this to make the table ready for use.
   */
  int dm_table_complete(struct dm_table *t);
  
  /*
   * Table reference counting.
   */
  struct dm_table *dm_get_table(struct mapped_device *md);
  void dm_table_get(struct dm_table *t);
  void dm_table_put(struct dm_table *t);
  
  /*
   * Queries
   */
  sector_t dm_table_get_size(struct dm_table *t);
  unsigned int dm_table_get_num_targets(struct dm_table *t);
  int dm_table_get_mode(struct dm_table *t);
  struct mapped_device *dm_table_get_md(struct dm_table *t);
  
  /*
   * Trigger an event.
   */
  void dm_table_event(struct dm_table *t);
  
  /*
   * The device must be suspended before calling this method.
   */
  int dm_swap_table(struct mapped_device *md, struct dm_table *t);

  /*
   * Prepare a table for a device that will error all I/O.
   * To make it active, call dm_suspend(), dm_swap_table() then dm_resume().
   */
  int dm_create_error_table(struct dm_table **result, struct mapped_device *md);

  #endif	/* __KERNEL__ */
  #endif	/* _LINUX_DEVICE_MAPPER_H */