include/linux/dm-kcopyd.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2001 - 2003 Sistina Software
   4  * Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
   5  *
   6  * kcopyd provides a simple interface for copying an area of one
   7  * block-device to one or more other block-devices, either synchronous
   8  * or with an asynchronous completion notification.
   9  *
  10  * This file is released under the GPL.
  11  */
  12
  13 #ifndef _LINUX_DM_KCOPYD_H
  14 #define _LINUX_DM_KCOPYD_H
  15
  16 #ifdef __KERNEL__
  17
  18 #include <linux/dm-io.h>
  19
  20 /* FIXME: make this configurable */
  21 #define DM_KCOPYD_MAX_REGIONS 8
  22
  23 #define DM_KCOPYD_IGNORE_ERROR 1
  24 #define DM_KCOPYD_WRITE_SEQ    2
  25
  26 struct dm_kcopyd_throttle {
  27         unsigned int throttle;
  28         unsigned int num_io_jobs;
  29         unsigned int io_period;
  30         unsigned int total_period;
  31         unsigned int last_jiffies;
  32 };
  33
  34 /*
  35  * kcopyd clients that want to support throttling must pass an initialised
  36  * dm_kcopyd_throttle struct into dm_kcopyd_client_create().
  37  * Two or more clients may share the same instance of this struct between
  38  * them if they wish to be throttled as a group.
  39  *
  40  * This macro also creates a corresponding module parameter to configure
  41  * the amount of throttling.
  42  */
  43 #define DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(name, description)  \
  44 static struct dm_kcopyd_throttle dm_kcopyd_throttle = { 100, 0, 0, 0, 0 }; \
  45 module_param_named(name, dm_kcopyd_throttle.throttle, uint, 0644); \
  46 MODULE_PARM_DESC(name, description)
  47
  48 /*
  49  * To use kcopyd you must first create a dm_kcopyd_client object.
  50  * throttle can be NULL if you don't want any throttling.
  51  */
  52 struct dm_kcopyd_client;
  53 struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle);
  54 void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc);
  55 void dm_kcopyd_client_flush(struct dm_kcopyd_client *kc);
  56
  57 /*
  58  * Submit a copy job to kcopyd.  This is built on top of the
  59  * previous three fns.
  60  *
  61  * read_err is a boolean,
  62  * write_err is a bitset, with 1 bit for each destination region
  63  */
  64 typedef void (*dm_kcopyd_notify_fn)(int read_err, unsigned int long write_err,
  65                                     void *context);
  66
  67 void dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
  68                     unsigned int num_dests, struct dm_io_region *dests,
  69                     unsigned int flags, dm_kcopyd_notify_fn fn, void *context);
  70
  71 /*
  72  * Prepare a callback and submit it via the kcopyd thread.
  73  *
  74  * dm_kcopyd_prepare_callback allocates a callback structure and returns it.
  75  * It must not be called from interrupt context.
  76  * The returned value should be passed into dm_kcopyd_do_callback.
  77  *
  78  * dm_kcopyd_do_callback submits the callback.
  79  * It may be called from interrupt context.
  80  * The callback is issued from the kcopyd thread.
  81  */
  82 void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
  83                                  dm_kcopyd_notify_fn fn, void *context);
  84 void dm_kcopyd_do_callback(void *job, int read_err, unsigned int long write_err);
  85
  86 void dm_kcopyd_zero(struct dm_kcopyd_client *kc,
  87                     unsigned int num_dests, struct dm_io_region *dests,
  88                     unsigned int flags, dm_kcopyd_notify_fn fn, void *context);
  89
  90 #endif  /* __KERNEL__ */
  91 #endif  /* _LINUX_DM_KCOPYD_H */