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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 { | |
493df71c JB |
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 | |
1e302a92 JB |
82 | unsigned (*status) (struct dm_exception_store *store, |
83 | status_type_t status, char *result, | |
84 | unsigned maxlen); | |
a159c1ac | 85 | |
aea53d92 JB |
86 | /* |
87 | * Return how full the snapshot is. | |
88 | */ | |
1ae25f9c | 89 | void (*fraction_full) (struct dm_exception_store *store, |
aea53d92 JB |
90 | sector_t *numerator, |
91 | sector_t *denominator); | |
493df71c JB |
92 | |
93 | /* For internal device-mapper use only. */ | |
94 | struct list_head list; | |
b2a11465 JB |
95 | }; |
96 | ||
97 | struct dm_exception_store { | |
493df71c | 98 | struct dm_exception_store_type *type; |
0cea9c78 | 99 | struct dm_target *ti; |
aea53d92 | 100 | |
49beb2b8 JB |
101 | struct dm_dev *cow; |
102 | ||
d0216849 JB |
103 | /* Size of data blocks saved - must be a power of 2 */ |
104 | chunk_t chunk_size; | |
105 | chunk_t chunk_mask; | |
106 | chunk_t chunk_shift; | |
107 | ||
aea53d92 JB |
108 | void *context; |
109 | }; | |
110 | ||
111 | /* | |
112 | * Funtions to manipulate consecutive chunks | |
113 | */ | |
90c699a9 | 114 | # if defined(CONFIG_LBDAF) || (BITS_PER_LONG == 64) |
aea53d92 JB |
115 | # define DM_CHUNK_CONSECUTIVE_BITS 8 |
116 | # define DM_CHUNK_NUMBER_BITS 56 | |
117 | ||
118 | static inline chunk_t dm_chunk_number(chunk_t chunk) | |
119 | { | |
120 | return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL); | |
121 | } | |
122 | ||
123 | static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e) | |
124 | { | |
125 | return e->new_chunk >> DM_CHUNK_NUMBER_BITS; | |
126 | } | |
127 | ||
128 | static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) | |
129 | { | |
130 | e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS); | |
131 | ||
132 | BUG_ON(!dm_consecutive_chunk_count(e)); | |
133 | } | |
134 | ||
135 | # else | |
136 | # define DM_CHUNK_CONSECUTIVE_BITS 0 | |
137 | ||
138 | static inline chunk_t dm_chunk_number(chunk_t chunk) | |
139 | { | |
140 | return chunk; | |
141 | } | |
142 | ||
143 | static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e) | |
144 | { | |
145 | return 0; | |
146 | } | |
147 | ||
148 | static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) | |
149 | { | |
150 | } | |
151 | ||
152 | # endif | |
153 | ||
71fab00a JB |
154 | /* |
155 | * Return the number of sectors in the device. | |
156 | */ | |
157 | static inline sector_t get_dev_size(struct block_device *bdev) | |
158 | { | |
159 | return bdev->bd_inode->i_size >> SECTOR_SHIFT; | |
160 | } | |
161 | ||
162 | static inline chunk_t sector_to_chunk(struct dm_exception_store *store, | |
163 | sector_t sector) | |
164 | { | |
165 | return (sector & ~store->chunk_mask) >> store->chunk_shift; | |
166 | } | |
167 | ||
493df71c JB |
168 | int dm_exception_store_type_register(struct dm_exception_store_type *type); |
169 | int dm_exception_store_type_unregister(struct dm_exception_store_type *type); | |
170 | ||
fee1998e JB |
171 | int dm_exception_store_create(struct dm_target *ti, int argc, char **argv, |
172 | unsigned *args_used, | |
493df71c JB |
173 | struct dm_exception_store **store); |
174 | void dm_exception_store_destroy(struct dm_exception_store *store); | |
175 | ||
4db6bfe0 AK |
176 | int dm_exception_store_init(void); |
177 | void dm_exception_store_exit(void); | |
178 | ||
aea53d92 JB |
179 | /* |
180 | * Two exception store implementations. | |
181 | */ | |
4db6bfe0 AK |
182 | int dm_persistent_snapshot_init(void); |
183 | void dm_persistent_snapshot_exit(void); | |
184 | ||
185 | int dm_transient_snapshot_init(void); | |
186 | void dm_transient_snapshot_exit(void); | |
187 | ||
aea53d92 | 188 | #endif /* _LINUX_DM_EXCEPTION_STORE */ |