1/*
2 * Copyright (C) 2003 Sistina Software
3 *
4 * This file is released under the LGPL.
5 */
6
7#ifndef DM_DIRTY_LOG
8#define DM_DIRTY_LOG
9
10#include "dm.h"
11
12typedef sector_t region_t;
13
14struct dirty_log_type;
15
16struct dirty_log {
17	struct dirty_log_type *type;
18	void *context;
19};
20
21struct dirty_log_type {
22	struct list_head list;
23	const char *name;
24	struct module *module;
25	unsigned int use_count;
26
27	int (*ctr)(struct dirty_log *log, struct dm_target *ti,
28		   unsigned int argc, char **argv);
29	void (*dtr)(struct dirty_log *log);
30
31	/*
32	 * There are times when we don't want the log to touch
33	 * the disk.
34	 */
35	int (*suspend)(struct dirty_log *log);
36	int (*resume)(struct dirty_log *log);
37
38	/*
39	 * Retrieves the smallest size of region that the log can
40	 * deal with.
41	 */
42	uint32_t (*get_region_size)(struct dirty_log *log);
43
44        /*
45	 * A predicate to say whether a region is clean or not.
46	 * May block.
47	 */
48	int (*is_clean)(struct dirty_log *log, region_t region);
49
50	/*
51	 *  Returns: 0, 1, -EWOULDBLOCK, < 0
52	 *
53	 * A predicate function to check the area given by
54	 * [sector, sector + len) is in sync.
55	 *
56	 * If -EWOULDBLOCK is returned the state of the region is
57	 * unknown, typically this will result in a read being
58	 * passed to a daemon to deal with, since a daemon is
59	 * allowed to block.
60	 */
61	int (*in_sync)(struct dirty_log *log, region_t region, int can_block);
62
63	/*
64	 * Flush the current log state (eg, to disk).  This
65	 * function may block.
66	 */
67	int (*flush)(struct dirty_log *log);
68
69	/*
70	 * Mark an area as clean or dirty.  These functions may
71	 * block, though for performance reasons blocking should
72	 * be extremely rare (eg, allocating another chunk of
73	 * memory for some reason).
74	 */
75	void (*mark_region)(struct dirty_log *log, region_t region);
76	void (*clear_region)(struct dirty_log *log, region_t region);
77
78	/*
79	 * Returns: <0 (error), 0 (no region), 1 (region)
80	 *
81	 * The mirrord will need perform recovery on regions of
82	 * the mirror that are in the NOSYNC state.  This
83	 * function asks the log to tell the caller about the
84	 * next region that this machine should recover.
85	 *
86	 * Do not confuse this function with 'in_sync()', one
87	 * tells you if an area is synchronised, the other
88	 * assigns recovery work.
89	*/
90	int (*get_resync_work)(struct dirty_log *log, region_t *region);
91
92	/*
93	 * This notifies the log that the resync status of a region
94	 * has changed.  It also clears the region from the recovering
95	 * list (if present).
96	 */
97	void (*set_region_sync)(struct dirty_log *log,
98				region_t region, int in_sync);
99
100        /*
101	 * Returns the number of regions that are in sync.
102         */
103        region_t (*get_sync_count)(struct dirty_log *log);
104
105	/*
106	 * Support function for mirror status requests.
107	 */
108	int (*status)(struct dirty_log *log, status_type_t status_type,
109		      char *result, unsigned int maxlen);
110};
111
112int dm_register_dirty_log_type(struct dirty_log_type *type);
113int dm_unregister_dirty_log_type(struct dirty_log_type *type);
114
115
116/*
117 * Make sure you use these two functions, rather than calling
118 * type->constructor/destructor() directly.
119 */
120struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
121				      unsigned int argc, char **argv);
122void dm_destroy_dirty_log(struct dirty_log *log);
123
124/*
125 * init/exit functions.
126 */
127int dm_dirty_log_init(void);
128void dm_dirty_log_exit(void);
129
130#endif
131