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3bd94003 | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
7a87edfe JT |
2 | /* |
3 | * Copyright (C) 2012 Red Hat, Inc. | |
4 | * | |
5 | * This file is released under the GPL. | |
6 | */ | |
7 | #ifndef _LINUX_DM_BITSET_H | |
8 | #define _LINUX_DM_BITSET_H | |
9 | ||
10 | #include "dm-array.h" | |
11 | ||
12 | /*----------------------------------------------------------------*/ | |
13 | ||
14 | /* | |
15 | * This bitset type is a thin wrapper round a dm_array of 64bit words. It | |
16 | * uses a tiny, one word cache to reduce the number of array lookups and so | |
17 | * increase performance. | |
18 | * | |
19 | * Like the dm-array that it's based on, the caller needs to keep track of | |
20 | * the size of the bitset separately. The underlying dm-array implicitly | |
21 | * knows how many words it's storing and will return -ENODATA if you try | |
22 | * and access an out of bounds word. However, an out of bounds bit in the | |
23 | * final word will _not_ be detected, you have been warned. | |
24 | * | |
25 | * Bits are indexed from zero. | |
26 | ||
27 | * Typical use: | |
28 | * | |
29 | * a) Initialise a dm_disk_bitset structure with dm_disk_bitset_init(). | |
30 | * This describes the bitset and includes the cache. It's not called it | |
31 | * dm_bitset_info in line with other data structures because it does | |
32 | * include instance data. | |
33 | * | |
34 | * b) Get yourself a root. The root is the index of a block of data on the | |
35 | * disk that holds a particular instance of an bitset. You may have a | |
36 | * pre existing root in your metadata that you wish to use, or you may | |
37 | * want to create a brand new, empty bitset with dm_bitset_empty(). | |
38 | * | |
39 | * Like the other data structures in this library, dm_bitset objects are | |
40 | * immutable between transactions. Update functions will return you the | |
41 | * root for a _new_ array. If you've incremented the old root, via | |
42 | * dm_tm_inc(), before calling the update function you may continue to use | |
43 | * it in parallel with the new root. | |
44 | * | |
45 | * Even read operations may trigger the cache to be flushed and as such | |
46 | * return a root for a new, updated bitset. | |
47 | * | |
48 | * c) resize a bitset with dm_bitset_resize(). | |
49 | * | |
50 | * d) Set a bit with dm_bitset_set_bit(). | |
51 | * | |
52 | * e) Clear a bit with dm_bitset_clear_bit(). | |
53 | * | |
54 | * f) Test a bit with dm_bitset_test_bit(). | |
55 | * | |
56 | * g) Flush all updates from the cache with dm_bitset_flush(). | |
57 | * | |
58 | * h) Destroy the bitset with dm_bitset_del(). This tells the transaction | |
59 | * manager that you're no longer using this data structure so it can | |
60 | * recycle it's blocks. (dm_bitset_dec() would be a better name for it, | |
61 | * but del is in keeping with dm_btree_del()). | |
62 | */ | |
63 | ||
64 | /* | |
65 | * Opaque object. Unlike dm_array_info, you should have one of these per | |
66 | * bitset. Initialise with dm_disk_bitset_init(). | |
67 | */ | |
68 | struct dm_disk_bitset { | |
69 | struct dm_array_info array_info; | |
70 | ||
71 | uint32_t current_index; | |
72 | uint64_t current_bits; | |
73 | ||
74 | bool current_index_set:1; | |
428e4698 | 75 | bool dirty:1; |
7a87edfe JT |
76 | }; |
77 | ||
78 | /* | |
79 | * Sets up a dm_disk_bitset structure. You don't need to do anything with | |
80 | * this structure when you finish using it. | |
81 | * | |
82 | * tm - the transaction manager that should supervise this structure | |
83 | * info - the structure being initialised | |
84 | */ | |
85 | void dm_disk_bitset_init(struct dm_transaction_manager *tm, | |
86 | struct dm_disk_bitset *info); | |
87 | ||
88 | /* | |
89 | * Create an empty, zero length bitset. | |
90 | * | |
91 | * info - describes the bitset | |
92 | * new_root - on success, points to the new root block | |
93 | */ | |
94 | int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *new_root); | |
95 | ||
2151249e JT |
96 | /* |
97 | * Creates a new bitset populated with values provided by a callback | |
98 | * function. This is more efficient than creating an empty bitset, | |
99 | * resizing, and then setting values since that process incurs a lot of | |
100 | * copying. | |
101 | * | |
102 | * info - describes the array | |
103 | * root - the root block of the array on disk | |
104 | * size - the number of entries in the array | |
105 | * fn - the callback | |
106 | * context - passed to the callback | |
107 | */ | |
108 | typedef int (*bit_value_fn)(uint32_t index, bool *value, void *context); | |
109 | int dm_bitset_new(struct dm_disk_bitset *info, dm_block_t *root, | |
110 | uint32_t size, bit_value_fn fn, void *context); | |
111 | ||
7a87edfe JT |
112 | /* |
113 | * Resize the bitset. | |
114 | * | |
115 | * info - describes the bitset | |
116 | * old_root - the root block of the array on disk | |
117 | * old_nr_entries - the number of bits in the old bitset | |
118 | * new_nr_entries - the number of bits you want in the new bitset | |
119 | * default_value - the value for any new bits | |
120 | * new_root - on success, points to the new root block | |
121 | */ | |
122 | int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t old_root, | |
123 | uint32_t old_nr_entries, uint32_t new_nr_entries, | |
124 | bool default_value, dm_block_t *new_root); | |
125 | ||
126 | /* | |
127 | * Frees the bitset. | |
128 | */ | |
129 | int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root); | |
130 | ||
131 | /* | |
132 | * Set a bit. | |
133 | * | |
134 | * info - describes the bitset | |
135 | * root - the root block of the bitset | |
136 | * index - the bit index | |
137 | * new_root - on success, points to the new root block | |
138 | * | |
139 | * -ENODATA will be returned if the index is out of bounds. | |
140 | */ | |
141 | int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root, | |
142 | uint32_t index, dm_block_t *new_root); | |
143 | ||
144 | /* | |
145 | * Clears a bit. | |
146 | * | |
147 | * info - describes the bitset | |
148 | * root - the root block of the bitset | |
149 | * index - the bit index | |
150 | * new_root - on success, points to the new root block | |
151 | * | |
152 | * -ENODATA will be returned if the index is out of bounds. | |
153 | */ | |
154 | int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root, | |
155 | uint32_t index, dm_block_t *new_root); | |
156 | ||
157 | /* | |
158 | * Tests a bit. | |
159 | * | |
160 | * info - describes the bitset | |
161 | * root - the root block of the bitset | |
162 | * index - the bit index | |
163 | * new_root - on success, points to the new root block (cached values may have been written) | |
164 | * result - the bit value you're after | |
165 | * | |
166 | * -ENODATA will be returned if the index is out of bounds. | |
167 | */ | |
168 | int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root, | |
169 | uint32_t index, dm_block_t *new_root, bool *result); | |
170 | ||
171 | /* | |
172 | * Flush any cached changes to disk. | |
173 | * | |
174 | * info - describes the bitset | |
175 | * root - the root block of the bitset | |
176 | * new_root - on success, points to the new root block | |
177 | */ | |
178 | int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root, | |
179 | dm_block_t *new_root); | |
180 | ||
6fe28dbf JT |
181 | struct dm_bitset_cursor { |
182 | struct dm_disk_bitset *info; | |
183 | struct dm_array_cursor cursor; | |
184 | ||
185 | uint32_t entries_remaining; | |
186 | uint32_t array_index; | |
187 | uint32_t bit_index; | |
188 | uint64_t current_bits; | |
189 | }; | |
190 | ||
191 | /* | |
192 | * Make sure you've flush any dm_disk_bitset and updated the root before | |
193 | * using this. | |
194 | */ | |
195 | int dm_bitset_cursor_begin(struct dm_disk_bitset *info, | |
196 | dm_block_t root, uint32_t nr_entries, | |
197 | struct dm_bitset_cursor *c); | |
198 | void dm_bitset_cursor_end(struct dm_bitset_cursor *c); | |
199 | ||
200 | int dm_bitset_cursor_next(struct dm_bitset_cursor *c); | |
9b696229 | 201 | int dm_bitset_cursor_skip(struct dm_bitset_cursor *c, uint32_t count); |
6fe28dbf JT |
202 | bool dm_bitset_cursor_get_value(struct dm_bitset_cursor *c); |
203 | ||
7a87edfe JT |
204 | /*----------------------------------------------------------------*/ |
205 | ||
206 | #endif /* _LINUX_DM_BITSET_H */ |