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 */
90