include/linux/dm-kcopyd.h

   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 #define DM_KCOPYD_WRITE_SEQ    2
  24
  25 struct dm_kcopyd_throttle {
  26         unsigned throttle;
  27         unsigned num_io_jobs;
  28         unsigned io_period;
  29         unsigned total_period;
  30         unsigned last_jiffies;
  31 };
  32
  33 /*
  34  * kcopyd clients that want to support throttling must pass an initialised
  35  * dm_kcopyd_throttle struct into dm_kcopyd_client_create().
  36  * Two or more clients may share the same instance of this struct between
  37  * them if they wish to be throttled as a group.
  38  *
  39  * This macro also creates a corresponding module parameter to configure
  40  * the amount of throttling.
  41  */
  42 #define DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(name, description)  \
  43 static struct dm_kcopyd_throttle dm_kcopyd_throttle = { 100, 0, 0, 0, 0 }; \
  44 module_param_named(name, dm_kcopyd_throttle.throttle, uint, 0644); \
  45 MODULE_PARM_DESC(name, description)
  46
  47 /*
  48  * To use kcopyd you must first create a dm_kcopyd_client object.
  49  * throttle can be NULL if you don't want any throttling.
  50  */
  51 struct dm_kcopyd_client;
  52 struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle);
  53 void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc);
  54
  55 /*
  56  * Submit a copy job to kcopyd.  This is built on top of the
  57  * previous three fns.
  58  *
  59  * read_err is a boolean,
  60  * write_err is a bitset, with 1 bit for each destination region
  61  */
  62 typedef void (*dm_kcopyd_notify_fn)(int read_err, unsigned long write_err,
  63                                     void *context);
  64
  65 int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
  66                    unsigned num_dests, struct dm_io_region *dests,
  67                    unsigned flags, dm_kcopyd_notify_fn fn, void *context);
  68
  69 /*
  70  * Prepare a callback and submit it via the kcopyd thread.
  71  *
  72  * dm_kcopyd_prepare_callback allocates a callback structure and returns it.
  73  * It must not be called from interrupt context.
  74  * The returned value should be passed into dm_kcopyd_do_callback.
  75  *
  76  * dm_kcopyd_do_callback submits the callback.
  77  * It may be called from interrupt context.
  78  * The callback is issued from the kcopyd thread.
  79  */
  80 void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
  81                                  dm_kcopyd_notify_fn fn, void *context);
  82 void dm_kcopyd_do_callback(void *job, int read_err, unsigned long write_err);
  83
  84 int dm_kcopyd_zero(struct dm_kcopyd_client *kc,
  85                    unsigned num_dests, struct dm_io_region *dests,
  86                    unsigned flags, dm_kcopyd_notify_fn fn, void *context);
  87
  88 #endif  /* __KERNEL__ */
  89 #endif  /* _LINUX_DM_KCOPYD_H */