summaryrefslogtreecommitdiffstats
path: root/drivers/block/zram/zcomp.c
blob: 965d1afb0eaa72558a1c6c36869e791733ec7350 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
/*
 * Copyright (C) 2014 Sergey Senozhatsky.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/sched.h>

#include "zcomp.h"
#include "zcomp_lzo.h"
#ifdef CONFIG_ZRAM_LZ4_COMPRESS
#include "zcomp_lz4.h"
#endif

/*
 * single zcomp_strm backend
 */
struct zcomp_strm_single {
	struct mutex strm_lock;
	struct zcomp_strm *zstrm;
};

/*
 * multi zcomp_strm backend
 */
struct zcomp_strm_multi {
	/* protect strm list */
	spinlock_t strm_lock;
	/* max possible number of zstrm streams */
	int max_strm;
	/* number of available zstrm streams */
	int avail_strm;
	/* list of available strms */
	struct list_head idle_strm;
	wait_queue_head_t strm_wait;
};

static struct zcomp_backend *backends[] = {
	&zcomp_lzo,
#ifdef CONFIG_ZRAM_LZ4_COMPRESS
	&zcomp_lz4,
#endif
	NULL
};

static struct zcomp_backend *find_backend(const char *compress)
{
	int i = 0;
	while (backends[i]) {
		if (sysfs_streq(compress, backends[i]->name))
			break;
		i++;
	}
	return backends[i];
}

static void zcomp_strm_free(struct zcomp *comp, struct zcomp_strm *zstrm)
{
	if (zstrm->private)
		comp->backend->destroy(zstrm->private);
	free_pages((unsigned long)zstrm->buffer, 1);
	kfree(zstrm);
}

/*
 * allocate new zcomp_strm structure with ->private initialized by
 * backend, return NULL on error
 */
static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
{
	struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
	if (!zstrm)
		return NULL;

	zstrm->private = comp->backend->create();
	/*
	 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
	 * case when compressed size is larger than the original one
	 */
	zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
	if (!zstrm->private || !zstrm->buffer) {
		zcomp_strm_free(comp, zstrm);
		zstrm = NULL;
	}
	return zstrm;
}

/*
 * get idle zcomp_strm or wait until other process release
 * (zcomp_strm_release()) one for us
 */
static struct zcomp_strm *zcomp_strm_multi_find(struct zcomp *comp)
{
	struct zcomp_strm_multi *zs = comp->stream;
	struct zcomp_strm *zstrm;

	while (1) {
		spin_lock(&zs->strm_lock);
		if (!list_empty(&zs->idle_strm)) {
			zstrm = list_entry(zs->idle_strm.next,
					struct zcomp_strm, list);
			list_del(&zstrm->list);
			spin_unlock(&zs->strm_lock);
			return zstrm;
		}
		/* zstrm streams limit reached, wait for idle stream */
		if (zs->avail_strm >= zs->max_strm) {
			spin_unlock(&zs->strm_lock);
			wait_event(zs->strm_wait, !list_empty(&zs->idle_strm));
			continue;
		}
		/* allocate new zstrm stream */
		zs->avail_strm++;
		spin_unlock(&zs->strm_lock);

		zstrm = zcomp_strm_alloc(comp);
		if (!zstrm) {
			spin_lock(&zs->strm_lock);
			zs->avail_strm--;
			spin_unlock(&zs->strm_lock);
			wait_event(zs->strm_wait, !list_empty(&zs->idle_strm));
			continue;
		}
		break;
	}
	return zstrm;
}

/* add stream back to idle list and wake up waiter or free the stream */
static void zcomp_strm_multi_release(struct zcomp *comp, struct zcomp_strm *zstrm)
{
	struct zcomp_strm_multi *zs = comp->stream;

	spin_lock(&zs->strm_lock);
	if (zs->avail_strm <= zs->max_strm) {
		list_add(&zstrm->list, &zs->idle_strm);
		spin_unlock(&zs->strm_lock);
		wake_up(&zs->strm_wait);
		return;
	}

	zs->avail_strm--;
	spin_unlock(&zs->strm_lock);
	zcomp_strm_free(comp, zstrm);
}

/* change max_strm limit */
static bool zcomp_strm_multi_set_max_streams(struct zcomp *comp, int num_strm)
{
	struct zcomp_strm_multi *zs = comp->stream;
	struct zcomp_strm *zstrm;

	spin_lock(&zs->strm_lock);
	zs->max_strm = num_strm;
	/*
	 * if user has lowered the limit and there are idle streams,
	 * immediately free as much streams (and memory) as we can.
	 */
	while (zs->avail_strm > num_strm && !list_empty(&zs->idle_strm)) {
		zstrm = list_entry(zs->idle_strm.next,
				struct zcomp_strm, list);
		list_del(&zstrm->list);
		zcomp_strm_free(comp, zstrm);
		zs->avail_strm--;
	}
	spin_unlock(&zs->strm_lock);
	return true;
}

static void zcomp_strm_multi_destroy(struct zcomp *comp)
{
	struct zcomp_strm_multi *zs = comp->stream;
	struct zcomp_strm *zstrm;

	while (!list_empty(&zs->idle_strm)) {
		zstrm = list_entry(zs->idle_strm.next,
				struct zcomp_strm, list);
		list_del(&zstrm->list);
		zcomp_strm_free(comp, zstrm);
	}
	kfree(zs);
}

static int zcomp_strm_multi_create(struct zcomp *comp, int max_strm)
{
	struct zcomp_strm *zstrm;
	struct zcomp_strm_multi *zs;

	comp->destroy = zcomp_strm_multi_destroy;
	comp->strm_find = zcomp_strm_multi_find;
	comp->strm_release = zcomp_strm_multi_release;
	comp->set_max_streams = zcomp_strm_multi_set_max_streams;
	zs = kmalloc(sizeof(struct zcomp_strm_multi), GFP_KERNEL);
	if (!zs)
		return -ENOMEM;

	comp->stream = zs;
	spin_lock_init(&zs->strm_lock);
	INIT_LIST_HEAD(&zs->idle_strm);
	init_waitqueue_head(&zs->strm_wait);
	zs->max_strm = max_strm;
	zs->avail_strm = 1;

	zstrm = zcomp_strm_alloc(comp);
	if (!zstrm) {
		kfree(zs);
		return -ENOMEM;
	}
	list_add(&zstrm->list, &zs->idle_strm);
	return 0;
}

static struct zcomp_strm *zcomp_strm_single_find(struct zcomp *comp)
{
	struct zcomp_strm_single *zs = comp->stream;
	mutex_lock(&zs->strm_lock);
	return zs->zstrm;
}

static void zcomp_strm_single_release(struct zcomp *comp,
		struct zcomp_strm *zstrm)
{
	struct zcomp_strm_single *zs = comp->stream;
	mutex_unlock(&zs->strm_lock);
}

static bool zcomp_strm_single_set_max_streams(struct zcomp *comp, int num_strm)
{
	/* zcomp_strm_single support only max_comp_streams == 1 */
	return false;
}

static void zcomp_strm_single_destroy(struct zcomp *comp)
{
	struct zcomp_strm_single *zs = comp->stream;
	zcomp_strm_free(comp, zs->zstrm);
	kfree(zs);
}

static int zcomp_strm_single_create(struct zcomp *comp)
{
	struct zcomp_strm_single *zs;

	comp->destroy = zcomp_strm_single_destroy;
	comp->strm_find = zcomp_strm_single_find;
	comp->strm_release = zcomp_strm_single_release;
	comp->set_max_streams = zcomp_strm_single_set_max_streams;
	zs = kmalloc(sizeof(struct zcomp_strm_single), GFP_KERNEL);
	if (!zs)
		return -ENOMEM;

	comp->stream = zs;
	mutex_init(&zs->strm_lock);
	zs->zstrm = zcomp_strm_alloc(comp);
	if (!zs->zstrm) {
		kfree(zs);
		return -ENOMEM;
	}
	return 0;
}

/* show available compressors */
ssize_t zcomp_available_show(const char *comp, char *buf)
{
	ssize_t sz = 0;
	int i = 0;

	while (backends[i]) {
		if (!strcmp(comp, backends[i]->name))
			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
					"[%s] ", backends[i]->name);
		else
			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
					"%s ", backends[i]->name);
		i++;
	}
	sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
	return sz;
}

bool zcomp_available_algorithm(const char *comp)
{
	return find_backend(comp) != NULL;
}

bool zcomp_set_max_streams(struct zcomp *comp, int num_strm)
{
	return comp->set_max_streams(comp, num_strm);
}

struct zcomp_strm *zcomp_strm_find(struct zcomp *comp)
{
	return comp->strm_find(comp);
}

void zcomp_strm_release(struct zcomp *comp, struct zcomp_strm *zstrm)
{
	comp->strm_release(comp, zstrm);
}

int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
		const unsigned char *src, size_t *dst_len)
{
	return comp->backend->compress(src, zstrm->buffer, dst_len,
			zstrm->private);
}

int zcomp_decompress(struct zcomp *comp, const unsigned char *src,
		size_t src_len, unsigned char *dst)
{
	return comp->backend->decompress(src, src_len, dst);
}

void zcomp_destroy(struct zcomp *comp)
{
	comp->destroy(comp);
	kfree(comp);
}

/*
 * search available compressors for requested algorithm.
 * allocate new zcomp and initialize it. return compressing
 * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
 * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
 * case of allocation error.
 */
struct zcomp *zcomp_create(const char *compress, int max_strm)
{
	struct zcomp *comp;
	struct zcomp_backend *backend;

	backend = find_backend(compress);
	if (!backend)
		return ERR_PTR(-EINVAL);

	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
	if (!comp)
		return ERR_PTR(-ENOMEM);

	comp->backend = backend;
	if (max_strm > 1)
		zcomp_strm_multi_create(comp, max_strm);
	else
		zcomp_strm_single_create(comp);
	if (!comp->stream) {
		kfree(comp);
		return ERR_PTR(-ENOMEM);
	}
	return comp;
}