2 * Copyright (C) 2014 Sergey Senozhatsky.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
10 #include <linux/kernel.h>
11 #include <linux/string.h>
12 #include <linux/err.h>
13 #include <linux/slab.h>
14 #include <linux/wait.h>
15 #include <linux/sched.h>
16 #include <linux/cpu.h>
17 #include <linux/crypto.h>
21 static const char * const backends[] = {
23 #ifdef CONFIG_ZRAM_LZ4_COMPRESS
29 static const char *find_backend(const char *compress)
33 if (sysfs_streq(compress, backends[i]))
40 static void zcomp_strm_free(struct zcomp_strm *zstrm)
42 if (!IS_ERR_OR_NULL(zstrm->tfm))
43 crypto_free_comp(zstrm->tfm);
44 free_pages((unsigned long)zstrm->buffer, 1);
49 * allocate new zcomp_strm structure with ->tfm initialized by
50 * backend, return NULL on error
52 static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp, gfp_t flags)
54 struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), flags);
58 zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
60 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
61 * case when compressed size is larger than the original one
63 zstrm->buffer = (void *)__get_free_pages(flags | __GFP_ZERO, 1);
64 if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
65 zcomp_strm_free(zstrm);
71 /* show available compressors */
72 ssize_t zcomp_available_show(const char *comp, char *buf)
78 if (!strcmp(comp, backends[i]))
79 sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
80 "[%s] ", backends[i]);
82 sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
86 sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
90 bool zcomp_available_algorithm(const char *comp)
92 return find_backend(comp) != NULL;
95 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
97 return *get_cpu_ptr(comp->stream);
100 void zcomp_stream_put(struct zcomp *comp)
102 put_cpu_ptr(comp->stream);
105 int zcomp_compress(struct zcomp_strm *zstrm,
106 const void *src, unsigned int *dst_len)
109 * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
110 * because sometimes we can endup having a bigger compressed data
111 * due to various reasons: for example compression algorithms tend
112 * to add some padding to the compressed buffer. Speaking of padding,
113 * comp algorithm `842' pads the compressed length to multiple of 8
114 * and returns -ENOSP when the dst memory is not big enough, which
115 * is not something that ZRAM wants to see. We can handle the
116 * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
117 * receive -ERRNO from the compressing backend we can't help it
118 * anymore. To make `842' happy we need to tell the exact size of
119 * the dst buffer, zram_drv will take care of the fact that
120 * compressed buffer is too big.
122 *dst_len = PAGE_SIZE * 2;
124 return crypto_comp_compress(zstrm->tfm,
126 zstrm->buffer, dst_len);
129 int zcomp_decompress(struct zcomp_strm *zstrm,
130 const void *src, unsigned int src_len, void *dst)
132 unsigned int dst_len = PAGE_SIZE;
134 return crypto_comp_decompress(zstrm->tfm,
139 static int __zcomp_cpu_notifier(struct zcomp *comp,
140 unsigned long action, unsigned long cpu)
142 struct zcomp_strm *zstrm;
146 if (WARN_ON(*per_cpu_ptr(comp->stream, cpu)))
148 zstrm = zcomp_strm_alloc(comp, GFP_KERNEL);
149 if (IS_ERR_OR_NULL(zstrm)) {
150 pr_err("Can't allocate a compression stream\n");
153 *per_cpu_ptr(comp->stream, cpu) = zstrm;
156 case CPU_UP_CANCELED:
157 zstrm = *per_cpu_ptr(comp->stream, cpu);
158 if (!IS_ERR_OR_NULL(zstrm))
159 zcomp_strm_free(zstrm);
160 *per_cpu_ptr(comp->stream, cpu) = NULL;
168 static int zcomp_cpu_notifier(struct notifier_block *nb,
169 unsigned long action, void *pcpu)
171 unsigned long cpu = (unsigned long)pcpu;
172 struct zcomp *comp = container_of(nb, typeof(*comp), notifier);
174 return __zcomp_cpu_notifier(comp, action, cpu);
177 static int zcomp_init(struct zcomp *comp)
182 comp->notifier.notifier_call = zcomp_cpu_notifier;
184 comp->stream = alloc_percpu(struct zcomp_strm *);
188 cpu_notifier_register_begin();
189 for_each_online_cpu(cpu) {
190 ret = __zcomp_cpu_notifier(comp, CPU_UP_PREPARE, cpu);
191 if (ret == NOTIFY_BAD)
194 __register_cpu_notifier(&comp->notifier);
195 cpu_notifier_register_done();
199 for_each_online_cpu(cpu)
200 __zcomp_cpu_notifier(comp, CPU_UP_CANCELED, cpu);
201 cpu_notifier_register_done();
205 void zcomp_destroy(struct zcomp *comp)
209 cpu_notifier_register_begin();
210 for_each_online_cpu(cpu)
211 __zcomp_cpu_notifier(comp, CPU_UP_CANCELED, cpu);
212 __unregister_cpu_notifier(&comp->notifier);
213 cpu_notifier_register_done();
215 free_percpu(comp->stream);
220 * search available compressors for requested algorithm.
221 * allocate new zcomp and initialize it. return compressing
222 * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
223 * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
224 * case of allocation error, or any other error potentially
225 * returned by zcomp_init().
227 struct zcomp *zcomp_create(const char *compress)
233 backend = find_backend(compress);
235 return ERR_PTR(-EINVAL);
237 comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
239 return ERR_PTR(-ENOMEM);
241 comp->name = backend;
242 error = zcomp_init(comp);
245 return ERR_PTR(error);