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 
49 #define DM_CACHE_FEATURE_COMPAT_SUPP	  0UL
50 #define DM_CACHE_FEATURE_COMPAT_RO_SUPP	  0UL
51 #define DM_CACHE_FEATURE_INCOMPAT_SUPP	  0UL
52 
53 /*
54  * Reopens or creates a new, empty metadata volume.  Returns an ERR_PTR on
55  * failure.  If reopening then features must match.
56  */
57 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
58 						 sector_t data_block_size,
59 						 bool may_format_device,
60 						 size_t policy_hint_size,
61 						 unsigned metadata_version);
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 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result);
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_bits(struct dm_cache_metadata *cmd,
97 			    unsigned nr_bits, unsigned long *bits);
98 
99 struct dm_cache_statistics {
100 	uint32_t read_hits;
101 	uint32_t read_misses;
102 	uint32_t write_hits;
103 	uint32_t write_misses;
104 };
105 
106 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
107 				 struct dm_cache_statistics *stats);
108 
109 /*
110  * 'void' because it's no big deal if it fails.
111  */
112 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
113 				 struct dm_cache_statistics *stats);
114 
115 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown);
116 
117 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
118 					   dm_block_t *result);
119 
120 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
121 				   dm_block_t *result);
122 
123 void dm_cache_dump(struct dm_cache_metadata *cmd);
124 
125 /*
126  * The policy is invited to save a 32bit hint value for every cblock (eg,
127  * for a hit count).  These are stored against the policy name.  If
128  * policies are changed, then hints will be lost.  If the machine crashes,
129  * hints will be lost.
130  *
131  * The hints are indexed by the cblock, but many policies will not
132  * neccessarily have a fast way of accessing efficiently via cblock.  So
133  * rather than querying the policy for each cblock, we let it walk its data
134  * structures and fill in the hints in whatever order it wishes.
135  */
136 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p);
137 
138 /*
139  * Query method.  Are all the blocks in the cache clean?
140  */
141 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result);
142 
143 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result);
144 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd);
145 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd);
146 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd);
147 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd);
148 
149 /*----------------------------------------------------------------*/
150 
151 #endif /* DM_CACHE_METADATA_H */
152