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
19typedef sector_t region_t;
20
21struct dm_dirty_log_type;
22
23struct dm_dirty_log {
24	struct dm_dirty_log_type *type;
25	int (*flush_callback_fn)(struct dm_target *ti);
26	void *context;
27};
28
29struct 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
133int dm_dirty_log_type_register(struct dm_dirty_log_type *type);
134int 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 */
140struct 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);
144void dm_dirty_log_destroy(struct dm_dirty_log *log);
145
146#endif	/* __KERNEL__ */
147#endif	/* _LINUX_DM_DIRTY_LOG_H */
148