1/*
2 * Copyright (C) 2003 Sistina Software
3 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
4 *
5 * Device-Mapper dirty region log.
6 *
7 * This file is released under the LGPL.
8 */
9
10#ifndef _LINUX_DM_DIRTY_LOG
11#define _LINUX_DM_DIRTY_LOG
12
13#ifdef __KERNEL__
14
15#include <linux/types.h>
16#include <linux/device-mapper.h>
17
18typedef sector_t region_t;
19
20struct dm_dirty_log_type;
21
22struct dm_dirty_log {
23	struct dm_dirty_log_type *type;
24	int (*flush_callback_fn)(struct dm_target *ti);
25	void *context;
26};
27
28struct dm_dirty_log_type {
29	const char *name;
30	struct module *module;
31
32	/* For internal device-mapper use */
33	struct list_head list;
34
35	int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
36		   unsigned argc, char **argv);
37	void (*dtr)(struct dm_dirty_log *log);
38
39	/*
40	 * There are times when we don't want the log to touch
41	 * the disk.
42	 */
43	int (*presuspend)(struct dm_dirty_log *log);
44	int (*postsuspend)(struct dm_dirty_log *log);
45	int (*resume)(struct dm_dirty_log *log);
46
47	/*
48	 * Retrieves the smallest size of region that the log can
49	 * deal with.
50	 */
51	uint32_t (*get_region_size)(struct dm_dirty_log *log);
52
53	/*
54	 * A predicate to say whether a region is clean or not.
55	 * May block.
56	 */
57	int (*is_clean)(struct dm_dirty_log *log, region_t region);
58
59	/*
60	 *  Returns: 0, 1, -EWOULDBLOCK, < 0
61	 *
62	 * A predicate function to check the area given by
63	 * [sector, sector + len) is in sync.
64	 *
65	 * If -EWOULDBLOCK is returned the state of the region is
66	 * unknown, typically this will result in a read being
67	 * passed to a daemon to deal with, since a daemon is
68	 * allowed to block.
69	 */
70	int (*in_sync)(struct dm_dirty_log *log, region_t region,
71		       int can_block);
72
73	/*
74	 * Flush the current log state (eg, to disk).  This
75	 * function may block.
76	 */
77	int (*flush)(struct dm_dirty_log *log);
78
79	/*
80	 * Mark an area as clean or dirty.  These functions may
81	 * block, though for performance reasons blocking should
82	 * be extremely rare (eg, allocating another chunk of
83	 * memory for some reason).
84	 */
85	void (*mark_region)(struct dm_dirty_log *log, region_t region);
86	void (*clear_region)(struct dm_dirty_log *log, region_t region);
87
88	/*
89	 * Returns: <0 (error), 0 (no region), 1 (region)
90	 *
91	 * The mirrord will need perform recovery on regions of
92	 * the mirror that are in the NOSYNC state.  This
93	 * function asks the log to tell the caller about the
94	 * next region that this machine should recover.
95	 *
96	 * Do not confuse this function with 'in_sync()', one
97	 * tells you if an area is synchronised, the other
98	 * assigns recovery work.
99	*/
100	int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
101
102	/*
103	 * This notifies the log that the resync status of a region
104	 * has changed.  It also clears the region from the recovering
105	 * list (if present).
106	 */
107	void (*set_region_sync)(struct dm_dirty_log *log,
108				region_t region, int in_sync);
109
110	/*
111	 * Returns the number of regions that are in sync.
112	 */
113	region_t (*get_sync_count)(struct dm_dirty_log *log);
114
115	/*
116	 * Support function for mirror status requests.
117	 */
118	int (*status)(struct dm_dirty_log *log, status_type_t status_type,
119		      char *result, unsigned maxlen);
120
121	/*
122	 * is_remote_recovering is necessary for cluster mirroring. It provides
123	 * a way to detect recovery on another node, so we aren't writing
124	 * concurrently.  This function is likely to block (when a cluster log
125	 * is used).
126	 *
127	 * Returns: 0, 1
128	 */
129	int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
130};
131
132int dm_dirty_log_type_register(struct dm_dirty_log_type *type);
133int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type);
134
135/*
136 * Make sure you use these two functions, rather than calling
137 * type->constructor/destructor() directly.
138 */
139struct dm_dirty_log *dm_dirty_log_create(const char *type_name,
140			struct dm_target *ti,
141			int (*flush_callback_fn)(struct dm_target *ti),
142			unsigned argc, char **argv);
143void dm_dirty_log_destroy(struct dm_dirty_log *log);
144
145#endif	/* __KERNEL__ */
146#endif	/* _LINUX_DM_DIRTY_LOG_H */
147