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3bd94003 | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
aea53d92 JB |
2 | /* |
3 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. | |
4 | * Copyright (C) 2008 Red Hat, Inc. All rights reserved. | |
5 | * | |
6 | * Device-mapper snapshot exception store. | |
7 | * | |
8 | * This file is released under the GPL. | |
9 | */ | |
10 | ||
11 | #ifndef _LINUX_DM_EXCEPTION_STORE | |
12 | #define _LINUX_DM_EXCEPTION_STORE | |
13 | ||
14 | #include <linux/blkdev.h> | |
f79ae415 | 15 | #include <linux/list_bl.h> |
a159c1ac | 16 | #include <linux/device-mapper.h> |
aea53d92 JB |
17 | |
18 | /* | |
19 | * The snapshot code deals with largish chunks of the disk at a | |
20 | * time. Typically 32k - 512k. | |
21 | */ | |
22 | typedef sector_t chunk_t; | |
23 | ||
24 | /* | |
25 | * An exception is used where an old chunk of data has been | |
26 | * replaced by a new one. | |
27 | * If chunk_t is 64 bits in size, the top 8 bits of new_chunk hold the number | |
28 | * of chunks that follow contiguously. Remaining bits hold the number of the | |
29 | * chunk within the device. | |
30 | */ | |
1d4989c8 | 31 | struct dm_exception { |
f79ae415 | 32 | struct hlist_bl_node hash_list; |
aea53d92 JB |
33 | |
34 | chunk_t old_chunk; | |
35 | chunk_t new_chunk; | |
36 | }; | |
37 | ||
38 | /* | |
39 | * Abstraction to handle the meta/layout of exception stores (the | |
40 | * COW device). | |
41 | */ | |
b2a11465 JB |
42 | struct dm_exception_store; |
43 | struct dm_exception_store_type { | |
493df71c JB |
44 | const char *name; |
45 | struct module *module; | |
46 | ||
8ca817c4 | 47 | int (*ctr)(struct dm_exception_store *store, char *options); |
b2a11465 | 48 | |
aea53d92 JB |
49 | /* |
50 | * Destroys this object when you've finished with it. | |
51 | */ | |
8ca817c4 | 52 | void (*dtr)(struct dm_exception_store *store); |
aea53d92 JB |
53 | |
54 | /* | |
55 | * The target shouldn't read the COW device until this is | |
a159c1ac JB |
56 | * called. As exceptions are read from the COW, they are |
57 | * reported back via the callback. | |
aea53d92 | 58 | */ |
8ca817c4 HM |
59 | int (*read_metadata)(struct dm_exception_store *store, |
60 | int (*callback)(void *callback_context, | |
61 | chunk_t old, chunk_t new), | |
62 | void *callback_context); | |
aea53d92 JB |
63 | |
64 | /* | |
65 | * Find somewhere to store the next exception. | |
66 | */ | |
8ca817c4 HM |
67 | int (*prepare_exception)(struct dm_exception_store *store, |
68 | struct dm_exception *e); | |
aea53d92 JB |
69 | |
70 | /* | |
71 | * Update the metadata with this exception. | |
72 | */ | |
8ca817c4 HM |
73 | void (*commit_exception)(struct dm_exception_store *store, |
74 | struct dm_exception *e, int valid, | |
75 | void (*callback)(void *, int success), | |
76 | void *callback_context); | |
aea53d92 | 77 | |
4454a621 MP |
78 | /* |
79 | * Returns 0 if the exception store is empty. | |
80 | * | |
81 | * If there are exceptions still to be merged, sets | |
82 | * *last_old_chunk and *last_new_chunk to the most recent | |
83 | * still-to-be-merged chunk and returns the number of | |
84 | * consecutive previous ones. | |
85 | */ | |
8ca817c4 HM |
86 | int (*prepare_merge)(struct dm_exception_store *store, |
87 | chunk_t *last_old_chunk, chunk_t *last_new_chunk); | |
4454a621 MP |
88 | |
89 | /* | |
90 | * Clear the last n exceptions. | |
91 | * nr_merged must be <= the value returned by prepare_merge. | |
92 | */ | |
8ca817c4 | 93 | int (*commit_merge)(struct dm_exception_store *store, int nr_merged); |
4454a621 | 94 | |
aea53d92 JB |
95 | /* |
96 | * The snapshot is invalid, note this in the metadata. | |
97 | */ | |
8ca817c4 | 98 | void (*drop_snapshot)(struct dm_exception_store *store); |
aea53d92 | 99 | |
8ca817c4 HM |
100 | unsigned int (*status)(struct dm_exception_store *store, |
101 | status_type_t status, char *result, | |
102 | unsigned int maxlen); | |
a159c1ac | 103 | |
aea53d92 JB |
104 | /* |
105 | * Return how full the snapshot is. | |
106 | */ | |
8ca817c4 HM |
107 | void (*usage)(struct dm_exception_store *store, |
108 | sector_t *total_sectors, sector_t *sectors_allocated, | |
109 | sector_t *metadata_sectors); | |
493df71c JB |
110 | |
111 | /* For internal device-mapper use only. */ | |
112 | struct list_head list; | |
b2a11465 JB |
113 | }; |
114 | ||
fc56f6fb MS |
115 | struct dm_snapshot; |
116 | ||
b2a11465 | 117 | struct dm_exception_store { |
493df71c | 118 | struct dm_exception_store_type *type; |
fc56f6fb | 119 | struct dm_snapshot *snap; |
49beb2b8 | 120 | |
d0216849 | 121 | /* Size of data blocks saved - must be a power of 2 */ |
86a3238c HM |
122 | unsigned int chunk_size; |
123 | unsigned int chunk_mask; | |
124 | unsigned int chunk_shift; | |
d0216849 | 125 | |
aea53d92 | 126 | void *context; |
b0d3cc01 MS |
127 | |
128 | bool userspace_supports_overflow; | |
aea53d92 JB |
129 | }; |
130 | ||
fc56f6fb | 131 | /* |
c2411045 | 132 | * Obtain the origin or cow device used by a given snapshot. |
fc56f6fb | 133 | */ |
c2411045 | 134 | struct dm_dev *dm_snap_origin(struct dm_snapshot *snap); |
fc56f6fb MS |
135 | struct dm_dev *dm_snap_cow(struct dm_snapshot *snap); |
136 | ||
aea53d92 JB |
137 | /* |
138 | * Funtions to manipulate consecutive chunks | |
139 | */ | |
72deb455 CH |
140 | #define DM_CHUNK_CONSECUTIVE_BITS 8 |
141 | #define DM_CHUNK_NUMBER_BITS 56 | |
aea53d92 JB |
142 | |
143 | static inline chunk_t dm_chunk_number(chunk_t chunk) | |
144 | { | |
145 | return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL); | |
146 | } | |
147 | ||
86a3238c | 148 | static inline unsigned int dm_consecutive_chunk_count(struct dm_exception *e) |
aea53d92 JB |
149 | { |
150 | return e->new_chunk >> DM_CHUNK_NUMBER_BITS; | |
151 | } | |
152 | ||
1d4989c8 | 153 | static inline void dm_consecutive_chunk_count_inc(struct dm_exception *e) |
aea53d92 JB |
154 | { |
155 | e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS); | |
156 | ||
157 | BUG_ON(!dm_consecutive_chunk_count(e)); | |
158 | } | |
159 | ||
1e03f97e MP |
160 | static inline void dm_consecutive_chunk_count_dec(struct dm_exception *e) |
161 | { | |
162 | BUG_ON(!dm_consecutive_chunk_count(e)); | |
163 | ||
164 | e->new_chunk -= (1ULL << DM_CHUNK_NUMBER_BITS); | |
165 | } | |
166 | ||
71fab00a JB |
167 | /* |
168 | * Return the number of sectors in the device. | |
169 | */ | |
170 | static inline sector_t get_dev_size(struct block_device *bdev) | |
171 | { | |
6dcbb52c | 172 | return bdev_nr_sectors(bdev); |
71fab00a JB |
173 | } |
174 | ||
175 | static inline chunk_t sector_to_chunk(struct dm_exception_store *store, | |
176 | sector_t sector) | |
177 | { | |
102c6ddb | 178 | return sector >> store->chunk_shift; |
71fab00a JB |
179 | } |
180 | ||
493df71c JB |
181 | int dm_exception_store_type_register(struct dm_exception_store_type *type); |
182 | int dm_exception_store_type_unregister(struct dm_exception_store_type *type); | |
183 | ||
2defcc3f | 184 | int dm_exception_store_set_chunk_size(struct dm_exception_store *store, |
86a3238c | 185 | unsigned int chunk_size, |
2defcc3f MP |
186 | char **error); |
187 | ||
fee1998e | 188 | int dm_exception_store_create(struct dm_target *ti, int argc, char **argv, |
fc56f6fb | 189 | struct dm_snapshot *snap, |
86a3238c | 190 | unsigned int *args_used, |
493df71c JB |
191 | struct dm_exception_store **store); |
192 | void dm_exception_store_destroy(struct dm_exception_store *store); | |
193 | ||
4db6bfe0 AK |
194 | int dm_exception_store_init(void); |
195 | void dm_exception_store_exit(void); | |
196 | ||
aea53d92 JB |
197 | /* |
198 | * Two exception store implementations. | |
199 | */ | |
4db6bfe0 AK |
200 | int dm_persistent_snapshot_init(void); |
201 | void dm_persistent_snapshot_exit(void); | |
202 | ||
203 | int dm_transient_snapshot_init(void); | |
204 | void dm_transient_snapshot_exit(void); | |
205 | ||
aea53d92 | 206 | #endif /* _LINUX_DM_EXCEPTION_STORE */ |