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aea53d92 JB |
1 | /* |
2 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. | |
3 | * Copyright (C) 2008 Red Hat, Inc. All rights reserved. | |
4 | * | |
5 | * Device-mapper snapshot exception store. | |
6 | * | |
7 | * This file is released under the GPL. | |
8 | */ | |
9 | ||
10 | #ifndef _LINUX_DM_EXCEPTION_STORE | |
11 | #define _LINUX_DM_EXCEPTION_STORE | |
12 | ||
13 | #include <linux/blkdev.h> | |
a159c1ac | 14 | #include <linux/device-mapper.h> |
aea53d92 JB |
15 | |
16 | /* | |
17 | * The snapshot code deals with largish chunks of the disk at a | |
18 | * time. Typically 32k - 512k. | |
19 | */ | |
20 | typedef sector_t chunk_t; | |
21 | ||
22 | /* | |
23 | * An exception is used where an old chunk of data has been | |
24 | * replaced by a new one. | |
25 | * If chunk_t is 64 bits in size, the top 8 bits of new_chunk hold the number | |
26 | * of chunks that follow contiguously. Remaining bits hold the number of the | |
27 | * chunk within the device. | |
28 | */ | |
29 | struct dm_snap_exception { | |
30 | struct list_head hash_list; | |
31 | ||
32 | chunk_t old_chunk; | |
33 | chunk_t new_chunk; | |
34 | }; | |
35 | ||
36 | /* | |
37 | * Abstraction to handle the meta/layout of exception stores (the | |
38 | * COW device). | |
39 | */ | |
b2a11465 JB |
40 | struct dm_exception_store; |
41 | struct dm_exception_store_type { | |
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42 | const char *name; |
43 | struct module *module; | |
44 | ||
b2a11465 JB |
45 | int (*ctr) (struct dm_exception_store *store, |
46 | unsigned argc, char **argv); | |
47 | ||
aea53d92 JB |
48 | /* |
49 | * Destroys this object when you've finished with it. | |
50 | */ | |
b2a11465 | 51 | void (*dtr) (struct dm_exception_store *store); |
aea53d92 JB |
52 | |
53 | /* | |
54 | * The target shouldn't read the COW device until this is | |
a159c1ac JB |
55 | * called. As exceptions are read from the COW, they are |
56 | * reported back via the callback. | |
aea53d92 | 57 | */ |
a159c1ac JB |
58 | int (*read_metadata) (struct dm_exception_store *store, |
59 | int (*callback)(void *callback_context, | |
60 | chunk_t old, chunk_t new), | |
61 | void *callback_context); | |
aea53d92 JB |
62 | |
63 | /* | |
64 | * Find somewhere to store the next exception. | |
65 | */ | |
1ae25f9c | 66 | int (*prepare_exception) (struct dm_exception_store *store, |
aea53d92 JB |
67 | struct dm_snap_exception *e); |
68 | ||
69 | /* | |
70 | * Update the metadata with this exception. | |
71 | */ | |
1ae25f9c | 72 | void (*commit_exception) (struct dm_exception_store *store, |
aea53d92 JB |
73 | struct dm_snap_exception *e, |
74 | void (*callback) (void *, int success), | |
75 | void *callback_context); | |
76 | ||
77 | /* | |
78 | * The snapshot is invalid, note this in the metadata. | |
79 | */ | |
1ae25f9c | 80 | void (*drop_snapshot) (struct dm_exception_store *store); |
aea53d92 | 81 | |
a159c1ac JB |
82 | int (*status) (struct dm_exception_store *store, status_type_t status, |
83 | char *result, unsigned int maxlen); | |
84 | ||
aea53d92 JB |
85 | /* |
86 | * Return how full the snapshot is. | |
87 | */ | |
1ae25f9c | 88 | void (*fraction_full) (struct dm_exception_store *store, |
aea53d92 JB |
89 | sector_t *numerator, |
90 | sector_t *denominator); | |
493df71c JB |
91 | |
92 | /* For internal device-mapper use only. */ | |
93 | struct list_head list; | |
b2a11465 JB |
94 | }; |
95 | ||
96 | struct dm_exception_store { | |
493df71c | 97 | struct dm_exception_store_type *type; |
0cea9c78 | 98 | struct dm_target *ti; |
aea53d92 JB |
99 | |
100 | struct dm_snapshot *snap; | |
b2a11465 | 101 | |
d0216849 JB |
102 | /* Size of data blocks saved - must be a power of 2 */ |
103 | chunk_t chunk_size; | |
104 | chunk_t chunk_mask; | |
105 | chunk_t chunk_shift; | |
106 | ||
aea53d92 JB |
107 | void *context; |
108 | }; | |
109 | ||
110 | /* | |
111 | * Funtions to manipulate consecutive chunks | |
112 | */ | |
113 | # if defined(CONFIG_LBD) || (BITS_PER_LONG == 64) | |
114 | # define DM_CHUNK_CONSECUTIVE_BITS 8 | |
115 | # define DM_CHUNK_NUMBER_BITS 56 | |
116 | ||
117 | static inline chunk_t dm_chunk_number(chunk_t chunk) | |
118 | { | |
119 | return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL); | |
120 | } | |
121 | ||
122 | static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e) | |
123 | { | |
124 | return e->new_chunk >> DM_CHUNK_NUMBER_BITS; | |
125 | } | |
126 | ||
127 | static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) | |
128 | { | |
129 | e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS); | |
130 | ||
131 | BUG_ON(!dm_consecutive_chunk_count(e)); | |
132 | } | |
133 | ||
134 | # else | |
135 | # define DM_CHUNK_CONSECUTIVE_BITS 0 | |
136 | ||
137 | static inline chunk_t dm_chunk_number(chunk_t chunk) | |
138 | { | |
139 | return chunk; | |
140 | } | |
141 | ||
142 | static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e) | |
143 | { | |
144 | return 0; | |
145 | } | |
146 | ||
147 | static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) | |
148 | { | |
149 | } | |
150 | ||
151 | # endif | |
152 | ||
493df71c JB |
153 | int dm_exception_store_type_register(struct dm_exception_store_type *type); |
154 | int dm_exception_store_type_unregister(struct dm_exception_store_type *type); | |
155 | ||
0cea9c78 | 156 | int dm_exception_store_create(const char *type_name, struct dm_target *ti, |
d0216849 JB |
157 | chunk_t chunk_size, chunk_t chunk_mask, |
158 | chunk_t chunk_shift, | |
493df71c JB |
159 | struct dm_exception_store **store); |
160 | void dm_exception_store_destroy(struct dm_exception_store *store); | |
161 | ||
4db6bfe0 AK |
162 | int dm_exception_store_init(void); |
163 | void dm_exception_store_exit(void); | |
164 | ||
aea53d92 JB |
165 | /* |
166 | * Two exception store implementations. | |
167 | */ | |
4db6bfe0 AK |
168 | int dm_persistent_snapshot_init(void); |
169 | void dm_persistent_snapshot_exit(void); | |
170 | ||
171 | int dm_transient_snapshot_init(void); | |
172 | void dm_transient_snapshot_exit(void); | |
173 | ||
aea53d92 | 174 | #endif /* _LINUX_DM_EXCEPTION_STORE */ |