1 /*
2  * Copyright (C) 2012 Red Hat, Inc.
3  *
4  * This file is released under the GPL.
5  */
6 
7 #include "dm-bitset.h"
8 #include "dm-transaction-manager.h"
9 
10 #include <linux/export.h>
11 #include <linux/device-mapper.h>
12 
13 #define DM_MSG_PREFIX "bitset"
14 #define BITS_PER_ARRAY_ENTRY 64
15 
16 /*----------------------------------------------------------------*/
17 
18 static struct dm_btree_value_type bitset_bvt = {
19 	.context = NULL,
20 	.size = sizeof(__le64),
21 	.inc = NULL,
22 	.dec = NULL,
23 	.equal = NULL,
24 };
25 
26 /*----------------------------------------------------------------*/
27 
28 void dm_disk_bitset_init(struct dm_transaction_manager *tm,
29 			 struct dm_disk_bitset *info)
30 {
31 	dm_array_info_init(&info->array_info, tm, &bitset_bvt);
32 	info->current_index_set = false;
33 }
34 EXPORT_SYMBOL_GPL(dm_disk_bitset_init);
35 
36 int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *root)
37 {
38 	return dm_array_empty(&info->array_info, root);
39 }
40 EXPORT_SYMBOL_GPL(dm_bitset_empty);
41 
42 struct packer_context {
43 	bit_value_fn fn;
44 	unsigned nr_bits;
45 	void *context;
46 };
47 
48 static int pack_bits(uint32_t index, void *value, void *context)
49 {
50 	int r;
51 	struct packer_context *p = context;
52 	unsigned bit, nr = min(64u, p->nr_bits - (index * 64));
53 	uint64_t word = 0;
54 	bool bv;
55 
56 	for (bit = 0; bit < nr; bit++) {
57 		r = p->fn(index * 64 + bit, &bv, p->context);
58 		if (r)
59 			return r;
60 
61 		if (bv)
62 			set_bit(bit, (unsigned long *) &word);
63 		else
64 			clear_bit(bit, (unsigned long *) &word);
65 	}
66 
67 	*((__le64 *) value) = cpu_to_le64(word);
68 
69 	return 0;
70 }
71 
72 int dm_bitset_new(struct dm_disk_bitset *info, dm_block_t *root,
73 		  uint32_t size, bit_value_fn fn, void *context)
74 {
75 	struct packer_context p;
76 	p.fn = fn;
77 	p.nr_bits = size;
78 	p.context = context;
79 
80 	return dm_array_new(&info->array_info, root, dm_div_up(size, 64), pack_bits, &p);
81 }
82 EXPORT_SYMBOL_GPL(dm_bitset_new);
83 
84 int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t root,
85 		     uint32_t old_nr_entries, uint32_t new_nr_entries,
86 		     bool default_value, dm_block_t *new_root)
87 {
88 	uint32_t old_blocks = dm_div_up(old_nr_entries, BITS_PER_ARRAY_ENTRY);
89 	uint32_t new_blocks = dm_div_up(new_nr_entries, BITS_PER_ARRAY_ENTRY);
90 	__le64 value = default_value ? cpu_to_le64(~0) : cpu_to_le64(0);
91 
92 	__dm_bless_for_disk(&value);
93 	return dm_array_resize(&info->array_info, root, old_blocks, new_blocks,
94 			       &value, new_root);
95 }
96 EXPORT_SYMBOL_GPL(dm_bitset_resize);
97 
98 int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root)
99 {
100 	return dm_array_del(&info->array_info, root);
101 }
102 EXPORT_SYMBOL_GPL(dm_bitset_del);
103 
104 int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root,
105 		    dm_block_t *new_root)
106 {
107 	int r;
108 	__le64 value;
109 
110 	if (!info->current_index_set || !info->dirty)
111 		return 0;
112 
113 	value = cpu_to_le64(info->current_bits);
114 
115 	__dm_bless_for_disk(&value);
116 	r = dm_array_set_value(&info->array_info, root, info->current_index,
117 			       &value, new_root);
118 	if (r)
119 		return r;
120 
121 	info->current_index_set = false;
122 	info->dirty = false;
123 
124 	return 0;
125 }
126 EXPORT_SYMBOL_GPL(dm_bitset_flush);
127 
128 static int read_bits(struct dm_disk_bitset *info, dm_block_t root,
129 		     uint32_t array_index)
130 {
131 	int r;
132 	__le64 value;
133 
134 	r = dm_array_get_value(&info->array_info, root, array_index, &value);
135 	if (r)
136 		return r;
137 
138 	info->current_bits = le64_to_cpu(value);
139 	info->current_index_set = true;
140 	info->current_index = array_index;
141 	info->dirty = false;
142 
143 	return 0;
144 }
145 
146 static int get_array_entry(struct dm_disk_bitset *info, dm_block_t root,
147 			   uint32_t index, dm_block_t *new_root)
148 {
149 	int r;
150 	unsigned array_index = index / BITS_PER_ARRAY_ENTRY;
151 
152 	if (info->current_index_set) {
153 		if (info->current_index == array_index)
154 			return 0;
155 
156 		r = dm_bitset_flush(info, root, new_root);
157 		if (r)
158 			return r;
159 	}
160 
161 	return read_bits(info, root, array_index);
162 }
163 
164 int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root,
165 		      uint32_t index, dm_block_t *new_root)
166 {
167 	int r;
168 	unsigned b = index % BITS_PER_ARRAY_ENTRY;
169 
170 	r = get_array_entry(info, root, index, new_root);
171 	if (r)
172 		return r;
173 
174 	set_bit(b, (unsigned long *) &info->current_bits);
175 	info->dirty = true;
176 
177 	return 0;
178 }
179 EXPORT_SYMBOL_GPL(dm_bitset_set_bit);
180 
181 int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root,
182 			uint32_t index, dm_block_t *new_root)
183 {
184 	int r;
185 	unsigned b = index % BITS_PER_ARRAY_ENTRY;
186 
187 	r = get_array_entry(info, root, index, new_root);
188 	if (r)
189 		return r;
190 
191 	clear_bit(b, (unsigned long *) &info->current_bits);
192 	info->dirty = true;
193 
194 	return 0;
195 }
196 EXPORT_SYMBOL_GPL(dm_bitset_clear_bit);
197 
198 int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root,
199 		       uint32_t index, dm_block_t *new_root, bool *result)
200 {
201 	int r;
202 	unsigned b = index % BITS_PER_ARRAY_ENTRY;
203 
204 	r = get_array_entry(info, root, index, new_root);
205 	if (r)
206 		return r;
207 
208 	*result = test_bit(b, (unsigned long *) &info->current_bits);
209 	return 0;
210 }
211 EXPORT_SYMBOL_GPL(dm_bitset_test_bit);
212 
213 static int cursor_next_array_entry(struct dm_bitset_cursor *c)
214 {
215 	int r;
216 	__le64 *value;
217 
218 	r = dm_array_cursor_next(&c->cursor);
219 	if (r)
220 		return r;
221 
222 	dm_array_cursor_get_value(&c->cursor, (void **) &value);
223 	c->array_index++;
224 	c->bit_index = 0;
225 	c->current_bits = le64_to_cpu(*value);
226 	return 0;
227 }
228 
229 int dm_bitset_cursor_begin(struct dm_disk_bitset *info,
230 			   dm_block_t root, uint32_t nr_entries,
231 			   struct dm_bitset_cursor *c)
232 {
233 	int r;
234 	__le64 *value;
235 
236 	if (!nr_entries)
237 		return -ENODATA;
238 
239 	c->info = info;
240 	c->entries_remaining = nr_entries;
241 
242 	r = dm_array_cursor_begin(&info->array_info, root, &c->cursor);
243 	if (r)
244 		return r;
245 
246 	dm_array_cursor_get_value(&c->cursor, (void **) &value);
247 	c->array_index = 0;
248 	c->bit_index = 0;
249 	c->current_bits = le64_to_cpu(*value);
250 
251 	return r;
252 }
253 EXPORT_SYMBOL_GPL(dm_bitset_cursor_begin);
254 
255 void dm_bitset_cursor_end(struct dm_bitset_cursor *c)
256 {
257 	return dm_array_cursor_end(&c->cursor);
258 }
259 EXPORT_SYMBOL_GPL(dm_bitset_cursor_end);
260 
261 int dm_bitset_cursor_next(struct dm_bitset_cursor *c)
262 {
263 	int r = 0;
264 
265 	if (!c->entries_remaining)
266 		return -ENODATA;
267 
268 	c->entries_remaining--;
269 	if (++c->bit_index > 63)
270 		r = cursor_next_array_entry(c);
271 
272 	return r;
273 }
274 EXPORT_SYMBOL_GPL(dm_bitset_cursor_next);
275 
276 int dm_bitset_cursor_skip(struct dm_bitset_cursor *c, uint32_t count)
277 {
278 	int r;
279 	__le64 *value;
280 	uint32_t nr_array_skip;
281 	uint32_t remaining_in_word = 64 - c->bit_index;
282 
283 	if (c->entries_remaining < count)
284 		return -ENODATA;
285 
286 	if (count < remaining_in_word) {
287 		c->bit_index += count;
288 		c->entries_remaining -= count;
289 		return 0;
290 
291 	} else {
292 		c->entries_remaining -= remaining_in_word;
293 		count -= remaining_in_word;
294 	}
295 
296 	nr_array_skip = (count / 64) + 1;
297 	r = dm_array_cursor_skip(&c->cursor, nr_array_skip);
298 	if (r)
299 		return r;
300 
301 	dm_array_cursor_get_value(&c->cursor, (void **) &value);
302 	c->entries_remaining -= count;
303 	c->array_index += nr_array_skip;
304 	c->bit_index = count & 63;
305 	c->current_bits = le64_to_cpu(*value);
306 
307 	return 0;
308 }
309 EXPORT_SYMBOL_GPL(dm_bitset_cursor_skip);
310 
311 bool dm_bitset_cursor_get_value(struct dm_bitset_cursor *c)
312 {
313 	return test_bit(c->bit_index, (unsigned long *) &c->current_bits);
314 }
315 EXPORT_SYMBOL_GPL(dm_bitset_cursor_get_value);
316 
317 /*----------------------------------------------------------------*/
318