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