/*
   * Copyright (C) 2001 - 2003 Sistina Software
   * Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
   *
   * kcopyd provides a simple interface for copying an area of one
   * block-device to one or more other block-devices, either synchronous
   * or with an asynchronous completion notification.
   *
   * This file is released under the GPL.
   */
  
  #ifndef _LINUX_DM_KCOPYD_H
  #define _LINUX_DM_KCOPYD_H
  
  #ifdef __KERNEL__
  
  #include <linux/dm-io.h>
  
  /* FIXME: make this configurable */
  #define DM_KCOPYD_MAX_REGIONS 8
  
  #define DM_KCOPYD_IGNORE_ERROR 1
  
  struct dm_kcopyd_throttle {
  	unsigned throttle;
  	unsigned num_io_jobs;
  	unsigned io_period;
  	unsigned total_period;
  	unsigned last_jiffies;
  };
  
  /*
   * kcopyd clients that want to support throttling must pass an initialised
   * dm_kcopyd_throttle struct into dm_kcopyd_client_create().
   * Two or more clients may share the same instance of this struct between
   * them if they wish to be throttled as a group.
   *
   * This macro also creates a corresponding module parameter to configure
   * the amount of throttling.
   */
  #define DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(name, description)	\
  static struct dm_kcopyd_throttle dm_kcopyd_throttle = { 100, 0, 0, 0, 0 }; \
  module_param_named(name, dm_kcopyd_throttle.throttle, uint, 0644); \
  MODULE_PARM_DESC(name, description)
  
  /*
   * To use kcopyd you must first create a dm_kcopyd_client object.
   * throttle can be NULL if you don't want any throttling.
   */
  struct dm_kcopyd_client;
  struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle);
  void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc);
  
  /*
   * Submit a copy job to kcopyd.  This is built on top of the
   * previous three fns.
   *
   * read_err is a boolean,
   * write_err is a bitset, with 1 bit for each destination region
   */
  typedef void (*dm_kcopyd_notify_fn)(int read_err, unsigned long write_err,
  				    void *context);
  
  int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
  		   unsigned num_dests, struct dm_io_region *dests,
  		   unsigned flags, dm_kcopyd_notify_fn fn, void *context);
  
  /*
   * Prepare a callback and submit it via the kcopyd thread.
   *
   * dm_kcopyd_prepare_callback allocates a callback structure and returns it.
   * It must not be called from interrupt context.
   * The returned value should be passed into dm_kcopyd_do_callback.
   *
   * dm_kcopyd_do_callback submits the callback.
   * It may be called from interrupt context.
   * The callback is issued from the kcopyd thread.
   */
  void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
  				 dm_kcopyd_notify_fn fn, void *context);
  void dm_kcopyd_do_callback(void *job, int read_err, unsigned long write_err);
  
  int dm_kcopyd_zero(struct dm_kcopyd_client *kc,
  		   unsigned num_dests, struct dm_io_region *dests,
  		   unsigned flags, dm_kcopyd_notify_fn fn, void *context);
  
  #endif	/* __KERNEL__ */
  #endif	/* _LINUX_DM_KCOPYD_H */