linux/include/linux/dm-kcopyd.h
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   1/*
   2 * Copyright (C) 2001 - 2003 Sistina Software
   3 * Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
   4 *
   5 * kcopyd provides a simple interface for copying an area of one
   6 * block-device to one or more other block-devices, either synchronous
   7 * or with an asynchronous completion notification.
   8 *
   9 * This file is released under the GPL.
  10 */
  11
  12#ifndef _LINUX_DM_KCOPYD_H
  13#define _LINUX_DM_KCOPYD_H
  14
  15#ifdef __KERNEL__
  16
  17#include <linux/dm-io.h>
  18
  19/* FIXME: make this configurable */
  20#define DM_KCOPYD_MAX_REGIONS 8
  21
  22#define DM_KCOPYD_IGNORE_ERROR 1
  23
  24struct dm_kcopyd_throttle {
  25        unsigned throttle;
  26        unsigned num_io_jobs;
  27        unsigned io_period;
  28        unsigned total_period;
  29        unsigned last_jiffies;
  30};
  31
  32/*
  33 * kcopyd clients that want to support throttling must pass an initialised
  34 * dm_kcopyd_throttle struct into dm_kcopyd_client_create().
  35 * Two or more clients may share the same instance of this struct between
  36 * them if they wish to be throttled as a group.
  37 *
  38 * This macro also creates a corresponding module parameter to configure
  39 * the amount of throttling.
  40 */
  41#define DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(name, description)  \
  42static struct dm_kcopyd_throttle dm_kcopyd_throttle = { 100, 0, 0, 0, 0 }; \
  43module_param_named(name, dm_kcopyd_throttle.throttle, uint, 0644); \
  44MODULE_PARM_DESC(name, description)
  45
  46/*
  47 * To use kcopyd you must first create a dm_kcopyd_client object.
  48 * throttle can be NULL if you don't want any throttling.
  49 */
  50struct dm_kcopyd_client;
  51struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle);
  52void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc);
  53
  54/*
  55 * Submit a copy job to kcopyd.  This is built on top of the
  56 * previous three fns.
  57 *
  58 * read_err is a boolean,
  59 * write_err is a bitset, with 1 bit for each destination region
  60 */
  61typedef void (*dm_kcopyd_notify_fn)(int read_err, unsigned long write_err,
  62                                    void *context);
  63
  64int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
  65                   unsigned num_dests, struct dm_io_region *dests,
  66                   unsigned flags, dm_kcopyd_notify_fn fn, void *context);
  67
  68/*
  69 * Prepare a callback and submit it via the kcopyd thread.
  70 *
  71 * dm_kcopyd_prepare_callback allocates a callback structure and returns it.
  72 * It must not be called from interrupt context.
  73 * The returned value should be passed into dm_kcopyd_do_callback.
  74 *
  75 * dm_kcopyd_do_callback submits the callback.
  76 * It may be called from interrupt context.
  77 * The callback is issued from the kcopyd thread.
  78 */
  79void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
  80                                 dm_kcopyd_notify_fn fn, void *context);
  81void dm_kcopyd_do_callback(void *job, int read_err, unsigned long write_err);
  82
  83int dm_kcopyd_zero(struct dm_kcopyd_client *kc,
  84                   unsigned num_dests, struct dm_io_region *dests,
  85                   unsigned flags, dm_kcopyd_notify_fn fn, void *context);
  86
  87#endif  /* __KERNEL__ */
  88#endif  /* _LINUX_DM_KCOPYD_H */
  89
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