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