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 void 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 void 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 */