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1 | /* |
2 | * Copyright (C) 2012 Red Hat, Inc. |
3 | * |
4 | * This file is released under the GPL. |
5 | */ |
6 | |
7 | #ifndef DM_CACHE_METADATA_H |
8 | #define DM_CACHE_METADATA_H |
9 | |
10 | #include "dm-cache-block-types.h" |
11 | #include "dm-cache-policy-internal.h" |
12 | |
13 | /*----------------------------------------------------------------*/ |
14 | |
15 | #define DM_CACHE_METADATA_BLOCK_SIZE 4096 |
16 | |
17 | /* FIXME: remove this restriction */ |
18 | /* |
19 | * The metadata device is currently limited in size. |
20 | * |
21 | * We have one block of index, which can hold 255 index entries. Each |
22 | * index entry contains allocation info about 16k metadata blocks. |
23 | */ |
24 | #define DM_CACHE_METADATA_MAX_SECTORS (255 * (1 << 14) * (DM_CACHE_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT))) |
25 | |
26 | /* |
27 | * A metadata device larger than 16GB triggers a warning. |
28 | */ |
29 | #define DM_CACHE_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT)) |
30 | |
31 | /*----------------------------------------------------------------*/ |
32 | |
33 | /* |
34 | * Ext[234]-style compat feature flags. |
35 | * |
36 | * A new feature which old metadata will still be compatible with should |
37 | * define a DM_CACHE_FEATURE_COMPAT_* flag (rarely useful). |
38 | * |
39 | * A new feature that is not compatible with old code should define a |
40 | * DM_CACHE_FEATURE_INCOMPAT_* flag and guard the relevant code with |
41 | * that flag. |
42 | * |
43 | * A new feature that is not compatible with old code accessing the |
44 | * metadata RDWR should define a DM_CACHE_FEATURE_RO_COMPAT_* flag and |
45 | * guard the relevant code with that flag. |
46 | * |
47 | * As these various flags are defined they should be added to the |
48 | * following masks. |
49 | */ |
50 | #define DM_CACHE_FEATURE_COMPAT_SUPP 0UL |
51 | #define DM_CACHE_FEATURE_COMPAT_RO_SUPP 0UL |
52 | #define DM_CACHE_FEATURE_INCOMPAT_SUPP 0UL |
53 | |
54 | /* |
55 | * Reopens or creates a new, empty metadata volume. |
56 | * Returns an ERR_PTR on failure. |
57 | */ |
58 | struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev, |
59 | sector_t data_block_size, |
60 | bool may_format_device, |
61 | size_t policy_hint_size); |
62 | |
63 | void dm_cache_metadata_close(struct dm_cache_metadata *cmd); |
64 | |
65 | /* |
66 | * The metadata needs to know how many cache blocks there are. We don't |
67 | * care about the origin, assuming the core target is giving us valid |
68 | * origin blocks to map to. |
69 | */ |
70 | int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size); |
71 | dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd); |
72 | |
73 | int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd, |
74 | sector_t discard_block_size, |
75 | dm_dblock_t new_nr_entries); |
76 | |
77 | typedef int (*load_discard_fn)(void *context, sector_t discard_block_size, |
78 | dm_dblock_t dblock, bool discarded); |
79 | int dm_cache_load_discards(struct dm_cache_metadata *cmd, |
80 | load_discard_fn fn, void *context); |
81 | |
82 | int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard); |
83 | |
84 | int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock); |
85 | int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock); |
86 | int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd); |
87 | |
88 | typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock, |
89 | dm_cblock_t cblock, bool dirty, |
90 | uint32_t hint, bool hint_valid); |
91 | int dm_cache_load_mappings(struct dm_cache_metadata *cmd, |
92 | struct dm_cache_policy *policy, |
93 | load_mapping_fn fn, |
94 | void *context); |
95 | |
96 | int dm_cache_set_dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty); |
97 | |
98 | struct dm_cache_statistics { |
99 | uint32_t read_hits; |
100 | uint32_t read_misses; |
101 | uint32_t write_hits; |
102 | uint32_t write_misses; |
103 | }; |
104 | |
105 | void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd, |
106 | struct dm_cache_statistics *stats); |
107 | void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd, |
108 | struct dm_cache_statistics *stats); |
109 | |
110 | int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown); |
111 | |
112 | int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd, |
113 | dm_block_t *result); |
114 | |
115 | int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd, |
116 | dm_block_t *result); |
117 | |
118 | void dm_cache_dump(struct dm_cache_metadata *cmd); |
119 | |
120 | /* |
121 | * The policy is invited to save a 32bit hint value for every cblock (eg, |
122 | * for a hit count). These are stored against the policy name. If |
123 | * policies are changed, then hints will be lost. If the machine crashes, |
124 | * hints will be lost. |
125 | * |
126 | * The hints are indexed by the cblock, but many policies will not |
127 | * neccessarily have a fast way of accessing efficiently via cblock. So |
128 | * rather than querying the policy for each cblock, we let it walk its data |
129 | * structures and fill in the hints in whatever order it wishes. |
130 | */ |
131 | |
132 | int dm_cache_begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p); |
133 | |
134 | /* |
135 | * requests hints for every cblock and stores in the metadata device. |
136 | */ |
137 | int dm_cache_save_hint(struct dm_cache_metadata *cmd, |
138 | dm_cblock_t cblock, uint32_t hint); |
139 | |
140 | /*----------------------------------------------------------------*/ |
141 | |
142 | #endif /* DM_CACHE_METADATA_H */ |
143 |
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