1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2003 Sistina Software
4 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
5 *
6 * Device-Mapper dirty region log.
7 *
8 * This file is released under the LGPL.
9 */
10
11 #ifndef _LINUX_DM_DIRTY_LOG
12 #define _LINUX_DM_DIRTY_LOG
13
14 #ifdef __KERNEL__
15
16 #include <linux/types.h>
17 #include <linux/device-mapper.h>
18
19 typedef sector_t region_t;
20
21 struct dm_dirty_log_type;
22
23 struct dm_dirty_log {
24 struct dm_dirty_log_type *type;
25 int (*flush_callback_fn)(struct dm_target *ti);
26 void *context;
27 };
28
29 struct dm_dirty_log_type {
30 const char *name;
31 struct module *module;
32
33 /* For internal device-mapper use */
34 struct list_head list;
35
36 int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
37 unsigned int argc, char **argv);
38 void (*dtr)(struct dm_dirty_log *log);
39
40 /*
41 * There are times when we don't want the log to touch
42 * the disk.
43 */
44 int (*presuspend)(struct dm_dirty_log *log);
45 int (*postsuspend)(struct dm_dirty_log *log);
46 int (*resume)(struct dm_dirty_log *log);
47
48 /*
49 * Retrieves the smallest size of region that the log can
50 * deal with.
51 */
52 uint32_t (*get_region_size)(struct dm_dirty_log *log);
53
54 /*
55 * A predicate to say whether a region is clean or not.
56 * May block.
57 */
58 int (*is_clean)(struct dm_dirty_log *log, region_t region);
59
60 /*
61 * Returns: 0, 1, -EWOULDBLOCK, < 0
62 *
63 * A predicate function to check the area given by
64 * [sector, sector + len) is in sync.
65 *
66 * If -EWOULDBLOCK is returned the state of the region is
67 * unknown, typically this will result in a read being
68 * passed to a daemon to deal with, since a daemon is
69 * allowed to block.
70 */
71 int (*in_sync)(struct dm_dirty_log *log, region_t region,
72 int can_block);
73
74 /*
75 * Flush the current log state (eg, to disk). This
76 * function may block.
77 */
78 int (*flush)(struct dm_dirty_log *log);
79
80 /*
81 * Mark an area as clean or dirty. These functions may
82 * block, though for performance reasons blocking should
83 * be extremely rare (eg, allocating another chunk of
84 * memory for some reason).
85 */
86 void (*mark_region)(struct dm_dirty_log *log, region_t region);
87 void (*clear_region)(struct dm_dirty_log *log, region_t region);
88
89 /*
90 * Returns: <0 (error), 0 (no region), 1 (region)
91 *
92 * The mirrord will need perform recovery on regions of
93 * the mirror that are in the NOSYNC state. This
94 * function asks the log to tell the caller about the
95 * next region that this machine should recover.
96 *
97 * Do not confuse this function with 'in_sync()', one
98 * tells you if an area is synchronised, the other
99 * assigns recovery work.
100 */
101 int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
102
103 /*
104 * This notifies the log that the resync status of a region
105 * has changed. It also clears the region from the recovering
106 * list (if present).
107 */
108 void (*set_region_sync)(struct dm_dirty_log *log,
109 region_t region, int in_sync);
110
111 /*
112 * Returns the number of regions that are in sync.
113 */
114 region_t (*get_sync_count)(struct dm_dirty_log *log);
115
116 /*
117 * Support function for mirror status requests.
118 */
119 int (*status)(struct dm_dirty_log *log, status_type_t status_type,
120 char *result, unsigned int maxlen);
121
122 /*
123 * is_remote_recovering is necessary for cluster mirroring. It provides
124 * a way to detect recovery on another node, so we aren't writing
125 * concurrently. This function is likely to block (when a cluster log
126 * is used).
127 *
128 * Returns: 0, 1
129 */
130 int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
131 };
132
133 int dm_dirty_log_type_register(struct dm_dirty_log_type *type);
134 int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type);
135
136 /*
137 * Make sure you use these two functions, rather than calling
138 * type->constructor/destructor() directly.
139 */
140 struct dm_dirty_log *dm_dirty_log_create(const char *type_name,
141 struct dm_target *ti,
142 int (*flush_callback_fn)(struct dm_target *ti),
143 unsigned int argc, char **argv);
144 void dm_dirty_log_destroy(struct dm_dirty_log *log);
145
146 #endif /* __KERNEL__ */
147 #endif /* _LINUX_DM_DIRTY_LOG_H */
148
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