zcomp.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2
  3#include <linux/kernel.h>
  4#include <linux/string.h>
  5#include <linux/err.h>
  6#include <linux/slab.h>
  7#include <linux/wait.h>
  8#include <linux/sched.h>
  9#include <linux/cpuhotplug.h>
 10#include <linux/vmalloc.h>
 11#include <linux/sysfs.h>
 12
 13#include "zcomp.h"
 14
 15#include "backend_lzo.h"
 16#include "backend_lzorle.h"
 17#include "backend_lz4.h"
 18#include "backend_lz4hc.h"
 19#include "backend_zstd.h"
 20#include "backend_deflate.h"
 21#include "backend_842.h"
 22
 23static const struct zcomp_ops *backends[] = {
 24#if IS_ENABLED(CONFIG_ZRAM_BACKEND_LZO)
 25	&backend_lzorle,
 26	&backend_lzo,
 27#endif
 28#if IS_ENABLED(CONFIG_ZRAM_BACKEND_LZ4)
 29	&backend_lz4,
 30#endif
 31#if IS_ENABLED(CONFIG_ZRAM_BACKEND_LZ4HC)
 32	&backend_lz4hc,
 33#endif
 34#if IS_ENABLED(CONFIG_ZRAM_BACKEND_ZSTD)
 35	&backend_zstd,
 36#endif
 37#if IS_ENABLED(CONFIG_ZRAM_BACKEND_DEFLATE)
 38	&backend_deflate,
 39#endif
 40#if IS_ENABLED(CONFIG_ZRAM_BACKEND_842)
 41	&backend_842,
 42#endif
 43	NULL
 44};
 45
 46static void zcomp_strm_free(struct zcomp *comp, struct zcomp_strm *zstrm)
 47{
 48	comp->ops->destroy_ctx(&zstrm->ctx);
 49	vfree(zstrm->local_copy);
 50	vfree(zstrm->buffer);
 51	zstrm->buffer = NULL;
 52}
 53
 54static int zcomp_strm_init(struct zcomp *comp, struct zcomp_strm *zstrm)
 55{
 56	int ret;
 57
 58	ret = comp->ops->create_ctx(comp->params, &zstrm->ctx);
 59	if (ret)
 60		return ret;
 61
 62	zstrm->local_copy = vzalloc(PAGE_SIZE);
 63	/*
 64	 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
 65	 * case when compressed size is larger than the original one
 66	 */
 67	zstrm->buffer = vzalloc(2 * PAGE_SIZE);
 68	if (!zstrm->buffer || !zstrm->local_copy) {
 69		zcomp_strm_free(comp, zstrm);
 70		return -ENOMEM;
 71	}
 72	return 0;
 73}
 74
 75static const struct zcomp_ops *lookup_backend_ops(const char *comp)
 76{
 77	int i = 0;
 78
 79	while (backends[i]) {
 80		if (sysfs_streq(comp, backends[i]->name))
 81			break;
 82		i++;
 83	}
 84	return backends[i];
 85}
 86
 87bool zcomp_available_algorithm(const char *comp)
 88{
 89	return lookup_backend_ops(comp) != NULL;
 90}
 91
 92/* show available compressors */
 93ssize_t zcomp_available_show(const char *comp, char *buf, ssize_t at)
 94{
 95	int i;
 96
 97	for (i = 0; i < ARRAY_SIZE(backends) - 1; i++) {
 98		if (!strcmp(comp, backends[i]->name)) {
 99			at += sysfs_emit_at(buf, at, "[%s] ",
100					    backends[i]->name);
101		} else {
102			at += sysfs_emit_at(buf, at, "%s ", backends[i]->name);
103		}
104	}
105
106	at += sysfs_emit_at(buf, at, "\n");
107	return at;
108}
109
110struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
111{
112	for (;;) {
113		struct zcomp_strm *zstrm = raw_cpu_ptr(comp->stream);
114
115		/*
116		 * Inspired by zswap
117		 *
118		 * stream is returned with ->mutex locked which prevents
119		 * cpu_dead() from releasing this stream under us, however
120		 * there is still a race window between raw_cpu_ptr() and
121		 * mutex_lock(), during which we could have been migrated
122		 * from a CPU that has already destroyed its stream.  If
123		 * so then unlock and re-try on the current CPU.
124		 */
125		mutex_lock(&zstrm->lock);
126		if (likely(zstrm->buffer))
127			return zstrm;
128		mutex_unlock(&zstrm->lock);
129	}
130}
131
132void zcomp_stream_put(struct zcomp_strm *zstrm)
133{
134	mutex_unlock(&zstrm->lock);
135}
136
137int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
138		   const void *src, unsigned int *dst_len)
139{
140	struct zcomp_req req = {
141		.src = src,
142		.dst = zstrm->buffer,
143		.src_len = PAGE_SIZE,
144		.dst_len = 2 * PAGE_SIZE,
145	};
146	int ret;
147
148	might_sleep();
149	ret = comp->ops->compress(comp->params, &zstrm->ctx, &req);
150	if (!ret)
151		*dst_len = req.dst_len;
152	return ret;
153}
154
155int zcomp_decompress(struct zcomp *comp, struct zcomp_strm *zstrm,
156		     const void *src, unsigned int src_len, void *dst)
157{
158	struct zcomp_req req = {
159		.src = src,
160		.dst = dst,
161		.src_len = src_len,
162		.dst_len = PAGE_SIZE,
163	};
164
165	might_sleep();
166	return comp->ops->decompress(comp->params, &zstrm->ctx, &req);
167}
168
169int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
170{
171	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
172	struct zcomp_strm *zstrm = per_cpu_ptr(comp->stream, cpu);
173	int ret;
174
175	ret = zcomp_strm_init(comp, zstrm);
176	if (ret)
177		pr_err("Can't allocate a compression stream\n");
178	return ret;
179}
180
181int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
182{
183	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
184	struct zcomp_strm *zstrm = per_cpu_ptr(comp->stream, cpu);
185
186	mutex_lock(&zstrm->lock);
187	zcomp_strm_free(comp, zstrm);
188	mutex_unlock(&zstrm->lock);
189	return 0;
190}
191
192static int zcomp_init(struct zcomp *comp, struct zcomp_params *params)
193{
194	int ret, cpu;
195
196	comp->stream = alloc_percpu(struct zcomp_strm);
197	if (!comp->stream)
198		return -ENOMEM;
199
200	comp->params = params;
201	ret = comp->ops->setup_params(comp->params);
202	if (ret)
203		goto cleanup;
204
205	for_each_possible_cpu(cpu)
206		mutex_init(&per_cpu_ptr(comp->stream, cpu)->lock);
207
208	ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
209	if (ret < 0)
210		goto cleanup;
211
212	return 0;
213
214cleanup:
215	comp->ops->release_params(comp->params);
216	free_percpu(comp->stream);
217	return ret;
218}
219
220void zcomp_destroy(struct zcomp *comp)
221{
222	cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
223	comp->ops->release_params(comp->params);
224	free_percpu(comp->stream);
225	kfree(comp);
226}
227
228struct zcomp *zcomp_create(const char *alg, struct zcomp_params *params)
229{
230	struct zcomp *comp;
231	int error;
232
233	/*
234	 * The backends array has a sentinel NULL value, so the minimum
235	 * size is 1. In order to be valid the array, apart from the
236	 * sentinel NULL element, should have at least one compression
237	 * backend selected.
238	 */
239	BUILD_BUG_ON(ARRAY_SIZE(backends) <= 1);
240
241	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
242	if (!comp)
243		return ERR_PTR(-ENOMEM);
244
245	comp->ops = lookup_backend_ops(alg);
246	if (!comp->ops) {
247		kfree(comp);
248		return ERR_PTR(-EINVAL);
249	}
250
251	error = zcomp_init(comp, params);
252	if (error) {
253		kfree(comp);
254		return ERR_PTR(error);
255	}
256	return comp;
257}