Commit | Line | Data |
---|---|---|
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 | */ | |
1ae25f9c | 40 | struct dm_exception_store { |
aea53d92 JB |
41 | /* |
42 | * Destroys this object when you've finished with it. | |
43 | */ | |
1ae25f9c | 44 | void (*destroy) (struct dm_exception_store *store); |
aea53d92 JB |
45 | |
46 | /* | |
47 | * The target shouldn't read the COW device until this is | |
a159c1ac JB |
48 | * called. As exceptions are read from the COW, they are |
49 | * reported back via the callback. | |
aea53d92 | 50 | */ |
a159c1ac JB |
51 | int (*read_metadata) (struct dm_exception_store *store, |
52 | int (*callback)(void *callback_context, | |
53 | chunk_t old, chunk_t new), | |
54 | void *callback_context); | |
aea53d92 JB |
55 | |
56 | /* | |
57 | * Find somewhere to store the next exception. | |
58 | */ | |
1ae25f9c | 59 | int (*prepare_exception) (struct dm_exception_store *store, |
aea53d92 JB |
60 | struct dm_snap_exception *e); |
61 | ||
62 | /* | |
63 | * Update the metadata with this exception. | |
64 | */ | |
1ae25f9c | 65 | void (*commit_exception) (struct dm_exception_store *store, |
aea53d92 JB |
66 | struct dm_snap_exception *e, |
67 | void (*callback) (void *, int success), | |
68 | void *callback_context); | |
69 | ||
70 | /* | |
71 | * The snapshot is invalid, note this in the metadata. | |
72 | */ | |
1ae25f9c | 73 | void (*drop_snapshot) (struct dm_exception_store *store); |
aea53d92 | 74 | |
a159c1ac JB |
75 | int (*status) (struct dm_exception_store *store, status_type_t status, |
76 | char *result, unsigned int maxlen); | |
77 | ||
aea53d92 JB |
78 | /* |
79 | * Return how full the snapshot is. | |
80 | */ | |
1ae25f9c | 81 | void (*fraction_full) (struct dm_exception_store *store, |
aea53d92 JB |
82 | sector_t *numerator, |
83 | sector_t *denominator); | |
84 | ||
85 | struct dm_snapshot *snap; | |
86 | void *context; | |
87 | }; | |
88 | ||
89 | /* | |
90 | * Funtions to manipulate consecutive chunks | |
91 | */ | |
92 | # if defined(CONFIG_LBD) || (BITS_PER_LONG == 64) | |
93 | # define DM_CHUNK_CONSECUTIVE_BITS 8 | |
94 | # define DM_CHUNK_NUMBER_BITS 56 | |
95 | ||
96 | static inline chunk_t dm_chunk_number(chunk_t chunk) | |
97 | { | |
98 | return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL); | |
99 | } | |
100 | ||
101 | static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e) | |
102 | { | |
103 | return e->new_chunk >> DM_CHUNK_NUMBER_BITS; | |
104 | } | |
105 | ||
106 | static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) | |
107 | { | |
108 | e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS); | |
109 | ||
110 | BUG_ON(!dm_consecutive_chunk_count(e)); | |
111 | } | |
112 | ||
113 | # else | |
114 | # define DM_CHUNK_CONSECUTIVE_BITS 0 | |
115 | ||
116 | static inline chunk_t dm_chunk_number(chunk_t chunk) | |
117 | { | |
118 | return chunk; | |
119 | } | |
120 | ||
121 | static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e) | |
122 | { | |
123 | return 0; | |
124 | } | |
125 | ||
126 | static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) | |
127 | { | |
128 | } | |
129 | ||
130 | # endif | |
131 | ||
4db6bfe0 AK |
132 | int dm_exception_store_init(void); |
133 | void dm_exception_store_exit(void); | |
134 | ||
aea53d92 JB |
135 | /* |
136 | * Two exception store implementations. | |
137 | */ | |
4db6bfe0 AK |
138 | int dm_persistent_snapshot_init(void); |
139 | void dm_persistent_snapshot_exit(void); | |
140 | ||
141 | int dm_transient_snapshot_init(void); | |
142 | void dm_transient_snapshot_exit(void); | |
143 | ||
1ae25f9c | 144 | int dm_create_persistent(struct dm_exception_store *store); |
aea53d92 | 145 | |
1ae25f9c | 146 | int dm_create_transient(struct dm_exception_store *store); |
aea53d92 JB |
147 | |
148 | #endif /* _LINUX_DM_EXCEPTION_STORE */ |