Commit | Line | Data |
---|---|---|
7a87edfe JT |
1 | /* |
2 | * Copyright (C) 2012 Red Hat, Inc. | |
3 | * | |
4 | * This file is released under the GPL. | |
5 | */ | |
6 | #ifndef _LINUX_DM_BITSET_H | |
7 | #define _LINUX_DM_BITSET_H | |
8 | ||
9 | #include "dm-array.h" | |
10 | ||
11 | /*----------------------------------------------------------------*/ | |
12 | ||
13 | /* | |
14 | * This bitset type is a thin wrapper round a dm_array of 64bit words. It | |
15 | * uses a tiny, one word cache to reduce the number of array lookups and so | |
16 | * increase performance. | |
17 | * | |
18 | * Like the dm-array that it's based on, the caller needs to keep track of | |
19 | * the size of the bitset separately. The underlying dm-array implicitly | |
20 | * knows how many words it's storing and will return -ENODATA if you try | |
21 | * and access an out of bounds word. However, an out of bounds bit in the | |
22 | * final word will _not_ be detected, you have been warned. | |
23 | * | |
24 | * Bits are indexed from zero. | |
25 | ||
26 | * Typical use: | |
27 | * | |
28 | * a) Initialise a dm_disk_bitset structure with dm_disk_bitset_init(). | |
29 | * This describes the bitset and includes the cache. It's not called it | |
30 | * dm_bitset_info in line with other data structures because it does | |
31 | * include instance data. | |
32 | * | |
33 | * b) Get yourself a root. The root is the index of a block of data on the | |
34 | * disk that holds a particular instance of an bitset. You may have a | |
35 | * pre existing root in your metadata that you wish to use, or you may | |
36 | * want to create a brand new, empty bitset with dm_bitset_empty(). | |
37 | * | |
38 | * Like the other data structures in this library, dm_bitset objects are | |
39 | * immutable between transactions. Update functions will return you the | |
40 | * root for a _new_ array. If you've incremented the old root, via | |
41 | * dm_tm_inc(), before calling the update function you may continue to use | |
42 | * it in parallel with the new root. | |
43 | * | |
44 | * Even read operations may trigger the cache to be flushed and as such | |
45 | * return a root for a new, updated bitset. | |
46 | * | |
47 | * c) resize a bitset with dm_bitset_resize(). | |
48 | * | |
49 | * d) Set a bit with dm_bitset_set_bit(). | |
50 | * | |
51 | * e) Clear a bit with dm_bitset_clear_bit(). | |
52 | * | |
53 | * f) Test a bit with dm_bitset_test_bit(). | |
54 | * | |
55 | * g) Flush all updates from the cache with dm_bitset_flush(). | |
56 | * | |
57 | * h) Destroy the bitset with dm_bitset_del(). This tells the transaction | |
58 | * manager that you're no longer using this data structure so it can | |
59 | * recycle it's blocks. (dm_bitset_dec() would be a better name for it, | |
60 | * but del is in keeping with dm_btree_del()). | |
61 | */ | |
62 | ||
63 | /* | |
64 | * Opaque object. Unlike dm_array_info, you should have one of these per | |
65 | * bitset. Initialise with dm_disk_bitset_init(). | |
66 | */ | |
67 | struct dm_disk_bitset { | |
68 | struct dm_array_info array_info; | |
69 | ||
70 | uint32_t current_index; | |
71 | uint64_t current_bits; | |
72 | ||
73 | bool current_index_set:1; | |
428e4698 | 74 | bool dirty:1; |
7a87edfe JT |
75 | }; |
76 | ||
77 | /* | |
78 | * Sets up a dm_disk_bitset structure. You don't need to do anything with | |
79 | * this structure when you finish using it. | |
80 | * | |
81 | * tm - the transaction manager that should supervise this structure | |
82 | * info - the structure being initialised | |
83 | */ | |
84 | void dm_disk_bitset_init(struct dm_transaction_manager *tm, | |
85 | struct dm_disk_bitset *info); | |
86 | ||
87 | /* | |
88 | * Create an empty, zero length bitset. | |
89 | * | |
90 | * info - describes the bitset | |
91 | * new_root - on success, points to the new root block | |
92 | */ | |
93 | int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *new_root); | |
94 | ||
95 | /* | |
96 | * Resize the bitset. | |
97 | * | |
98 | * info - describes the bitset | |
99 | * old_root - the root block of the array on disk | |
100 | * old_nr_entries - the number of bits in the old bitset | |
101 | * new_nr_entries - the number of bits you want in the new bitset | |
102 | * default_value - the value for any new bits | |
103 | * new_root - on success, points to the new root block | |
104 | */ | |
105 | int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t old_root, | |
106 | uint32_t old_nr_entries, uint32_t new_nr_entries, | |
107 | bool default_value, dm_block_t *new_root); | |
108 | ||
109 | /* | |
110 | * Frees the bitset. | |
111 | */ | |
112 | int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root); | |
113 | ||
114 | /* | |
115 | * Set a bit. | |
116 | * | |
117 | * info - describes the bitset | |
118 | * root - the root block of the bitset | |
119 | * index - the bit index | |
120 | * new_root - on success, points to the new root block | |
121 | * | |
122 | * -ENODATA will be returned if the index is out of bounds. | |
123 | */ | |
124 | int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root, | |
125 | uint32_t index, dm_block_t *new_root); | |
126 | ||
127 | /* | |
128 | * Clears a bit. | |
129 | * | |
130 | * info - describes the bitset | |
131 | * root - the root block of the bitset | |
132 | * index - the bit index | |
133 | * new_root - on success, points to the new root block | |
134 | * | |
135 | * -ENODATA will be returned if the index is out of bounds. | |
136 | */ | |
137 | int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root, | |
138 | uint32_t index, dm_block_t *new_root); | |
139 | ||
140 | /* | |
141 | * Tests a bit. | |
142 | * | |
143 | * info - describes the bitset | |
144 | * root - the root block of the bitset | |
145 | * index - the bit index | |
146 | * new_root - on success, points to the new root block (cached values may have been written) | |
147 | * result - the bit value you're after | |
148 | * | |
149 | * -ENODATA will be returned if the index is out of bounds. | |
150 | */ | |
151 | int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root, | |
152 | uint32_t index, dm_block_t *new_root, bool *result); | |
153 | ||
154 | /* | |
155 | * Flush any cached changes to disk. | |
156 | * | |
157 | * info - describes the bitset | |
158 | * root - the root block of the bitset | |
159 | * new_root - on success, points to the new root block | |
160 | */ | |
161 | int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root, | |
162 | dm_block_t *new_root); | |
163 | ||
164 | /*----------------------------------------------------------------*/ | |
165 | ||
166 | #endif /* _LINUX_DM_BITSET_H */ |