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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> | |
f79ae415 | 14 | #include <linux/list_bl.h> |
a159c1ac | 15 | #include <linux/device-mapper.h> |
aea53d92 JB |
16 | |
17 | /* | |
18 | * The snapshot code deals with largish chunks of the disk at a | |
19 | * time. Typically 32k - 512k. | |
20 | */ | |
21 | typedef sector_t chunk_t; | |
22 | ||
23 | /* | |
24 | * An exception is used where an old chunk of data has been | |
25 | * replaced by a new one. | |
26 | * If chunk_t is 64 bits in size, the top 8 bits of new_chunk hold the number | |
27 | * of chunks that follow contiguously. Remaining bits hold the number of the | |
28 | * chunk within the device. | |
29 | */ | |
1d4989c8 | 30 | struct dm_exception { |
f79ae415 | 31 | struct hlist_bl_node hash_list; |
aea53d92 JB |
32 | |
33 | chunk_t old_chunk; | |
34 | chunk_t new_chunk; | |
35 | }; | |
36 | ||
37 | /* | |
38 | * Abstraction to handle the meta/layout of exception stores (the | |
39 | * COW device). | |
40 | */ | |
b2a11465 JB |
41 | struct dm_exception_store; |
42 | struct dm_exception_store_type { | |
493df71c JB |
43 | const char *name; |
44 | struct module *module; | |
45 | ||
b0d3cc01 | 46 | int (*ctr) (struct dm_exception_store *store, char *options); |
b2a11465 | 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, |
1d4989c8 | 67 | struct dm_exception *e); |
aea53d92 JB |
68 | |
69 | /* | |
70 | * Update the metadata with this exception. | |
71 | */ | |
1ae25f9c | 72 | void (*commit_exception) (struct dm_exception_store *store, |
385277bf | 73 | struct dm_exception *e, int valid, |
aea53d92 JB |
74 | void (*callback) (void *, int success), |
75 | void *callback_context); | |
76 | ||
4454a621 MP |
77 | /* |
78 | * Returns 0 if the exception store is empty. | |
79 | * | |
80 | * If there are exceptions still to be merged, sets | |
81 | * *last_old_chunk and *last_new_chunk to the most recent | |
82 | * still-to-be-merged chunk and returns the number of | |
83 | * consecutive previous ones. | |
84 | */ | |
85 | int (*prepare_merge) (struct dm_exception_store *store, | |
86 | chunk_t *last_old_chunk, chunk_t *last_new_chunk); | |
87 | ||
88 | /* | |
89 | * Clear the last n exceptions. | |
90 | * nr_merged must be <= the value returned by prepare_merge. | |
91 | */ | |
92 | int (*commit_merge) (struct dm_exception_store *store, int nr_merged); | |
93 | ||
aea53d92 JB |
94 | /* |
95 | * The snapshot is invalid, note this in the metadata. | |
96 | */ | |
1ae25f9c | 97 | void (*drop_snapshot) (struct dm_exception_store *store); |
aea53d92 | 98 | |
1e302a92 JB |
99 | unsigned (*status) (struct dm_exception_store *store, |
100 | status_type_t status, char *result, | |
101 | unsigned maxlen); | |
a159c1ac | 102 | |
aea53d92 JB |
103 | /* |
104 | * Return how full the snapshot is. | |
105 | */ | |
985903bb MS |
106 | void (*usage) (struct dm_exception_store *store, |
107 | sector_t *total_sectors, sector_t *sectors_allocated, | |
108 | sector_t *metadata_sectors); | |
493df71c JB |
109 | |
110 | /* For internal device-mapper use only. */ | |
111 | struct list_head list; | |
b2a11465 JB |
112 | }; |
113 | ||
fc56f6fb MS |
114 | struct dm_snapshot; |
115 | ||
b2a11465 | 116 | struct dm_exception_store { |
493df71c | 117 | struct dm_exception_store_type *type; |
fc56f6fb | 118 | struct dm_snapshot *snap; |
49beb2b8 | 119 | |
d0216849 | 120 | /* Size of data blocks saved - must be a power of 2 */ |
df96eee6 MP |
121 | unsigned chunk_size; |
122 | unsigned chunk_mask; | |
123 | unsigned chunk_shift; | |
d0216849 | 124 | |
aea53d92 | 125 | void *context; |
b0d3cc01 MS |
126 | |
127 | bool userspace_supports_overflow; | |
aea53d92 JB |
128 | }; |
129 | ||
fc56f6fb | 130 | /* |
c2411045 | 131 | * Obtain the origin or cow device used by a given snapshot. |
fc56f6fb | 132 | */ |
c2411045 | 133 | struct dm_dev *dm_snap_origin(struct dm_snapshot *snap); |
fc56f6fb MS |
134 | struct dm_dev *dm_snap_cow(struct dm_snapshot *snap); |
135 | ||
aea53d92 JB |
136 | /* |
137 | * Funtions to manipulate consecutive chunks | |
138 | */ | |
72deb455 CH |
139 | #define DM_CHUNK_CONSECUTIVE_BITS 8 |
140 | #define DM_CHUNK_NUMBER_BITS 56 | |
aea53d92 JB |
141 | |
142 | static inline chunk_t dm_chunk_number(chunk_t chunk) | |
143 | { | |
144 | return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL); | |
145 | } | |
146 | ||
1d4989c8 | 147 | static inline unsigned dm_consecutive_chunk_count(struct dm_exception *e) |
aea53d92 JB |
148 | { |
149 | return e->new_chunk >> DM_CHUNK_NUMBER_BITS; | |
150 | } | |
151 | ||
1d4989c8 | 152 | static inline void dm_consecutive_chunk_count_inc(struct dm_exception *e) |
aea53d92 JB |
153 | { |
154 | e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS); | |
155 | ||
156 | BUG_ON(!dm_consecutive_chunk_count(e)); | |
157 | } | |
158 | ||
1e03f97e MP |
159 | static inline void dm_consecutive_chunk_count_dec(struct dm_exception *e) |
160 | { | |
161 | BUG_ON(!dm_consecutive_chunk_count(e)); | |
162 | ||
163 | e->new_chunk -= (1ULL << DM_CHUNK_NUMBER_BITS); | |
164 | } | |
165 | ||
71fab00a JB |
166 | /* |
167 | * Return the number of sectors in the device. | |
168 | */ | |
169 | static inline sector_t get_dev_size(struct block_device *bdev) | |
170 | { | |
5657e8fa | 171 | return i_size_read(bdev->bd_inode) >> SECTOR_SHIFT; |
71fab00a JB |
172 | } |
173 | ||
174 | static inline chunk_t sector_to_chunk(struct dm_exception_store *store, | |
175 | sector_t sector) | |
176 | { | |
102c6ddb | 177 | return sector >> store->chunk_shift; |
71fab00a JB |
178 | } |
179 | ||
493df71c JB |
180 | int dm_exception_store_type_register(struct dm_exception_store_type *type); |
181 | int dm_exception_store_type_unregister(struct dm_exception_store_type *type); | |
182 | ||
2defcc3f | 183 | int dm_exception_store_set_chunk_size(struct dm_exception_store *store, |
df96eee6 | 184 | unsigned chunk_size, |
2defcc3f MP |
185 | char **error); |
186 | ||
fee1998e | 187 | int dm_exception_store_create(struct dm_target *ti, int argc, char **argv, |
fc56f6fb | 188 | struct dm_snapshot *snap, |
fee1998e | 189 | unsigned *args_used, |
493df71c JB |
190 | struct dm_exception_store **store); |
191 | void dm_exception_store_destroy(struct dm_exception_store *store); | |
192 | ||
4db6bfe0 AK |
193 | int dm_exception_store_init(void); |
194 | void dm_exception_store_exit(void); | |
195 | ||
aea53d92 JB |
196 | /* |
197 | * Two exception store implementations. | |
198 | */ | |
4db6bfe0 AK |
199 | int dm_persistent_snapshot_init(void); |
200 | void dm_persistent_snapshot_exit(void); | |
201 | ||
202 | int dm_transient_snapshot_init(void); | |
203 | void dm_transient_snapshot_exit(void); | |
204 | ||
aea53d92 | 205 | #endif /* _LINUX_DM_EXCEPTION_STORE */ |