drivers/block/zram/zcomp.c

   1 /*
   2  * Copyright (C) 2014 Sergey Senozhatsky.
   3  *
   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.
   8  */
   9
  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>
  18
  19 #include "zcomp.h"
  20
  21 static const char * const backends[] = {
  22         "lzo",
  23         "lzo-rle",
  24 #if IS_ENABLED(CONFIG_CRYPTO_LZ4)
  25         "lz4",
  26 #endif
  27 #if IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
  28         "lz4hc",
  29 #endif
  30 #if IS_ENABLED(CONFIG_CRYPTO_842)
  31         "842",
  32 #endif
  33 #if IS_ENABLED(CONFIG_CRYPTO_ZSTD)
  34         "zstd",
  35 #endif
  36         NULL
  37 };
  38
  39 static void zcomp_strm_free(struct zcomp_strm *zstrm)
  40 {
  41         if (!IS_ERR_OR_NULL(zstrm->tfm))
  42                 crypto_free_comp(zstrm->tfm);
  43         free_pages((unsigned long)zstrm->buffer, 1);
  44         kfree(zstrm);
  45 }
  46
  47 /*
  48  * allocate new zcomp_strm structure with ->tfm initialized by
  49  * backend, return NULL on error
  50  */
  51 static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
  52 {
  53         struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
  54         if (!zstrm)
  55                 return NULL;
  56
  57         zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
  58         /*
  59          * allocate 2 pages. 1 for compressed data, plus 1 extra for the
  60          * case when compressed size is larger than the original one
  61          */
  62         zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
  63         if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
  64                 zcomp_strm_free(zstrm);
  65                 zstrm = NULL;
  66         }
  67         return zstrm;
  68 }
  69
  70 bool zcomp_available_algorithm(const char *comp)
  71 {
  72         int i;
  73
  74         i = __sysfs_match_string(backends, -1, comp);
  75         if (i >= 0)
  76                 return true;
  77
  78         /*
  79          * Crypto does not ignore a trailing new line symbol,
  80          * so make sure you don't supply a string containing
  81          * one.
  82          * This also means that we permit zcomp initialisation
  83          * with any compressing algorithm known to crypto api.
  84          */
  85         return crypto_has_comp(comp, 0, 0) == 1;
  86 }
  87
  88 /* show available compressors */
  89 ssize_t zcomp_available_show(const char *comp, char *buf)
  90 {
  91         bool known_algorithm = false;
  92         ssize_t sz = 0;
  93         int i = 0;
  94
  95         for (; backends[i]; i++) {
  96                 if (!strcmp(comp, backends[i])) {
  97                         known_algorithm = true;
  98                         sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
  99                                         "[%s] ", backends[i]);
 100                 } else {
 101                         sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
 102                                         "%s ", backends[i]);
 103                 }
 104         }
 105
 106         /*
 107          * Out-of-tree module known to crypto api or a missing
 108          * entry in `backends'.
 109          */
 110         if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
 111                 sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
 112                                 "[%s] ", comp);
 113
 114         sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
 115         return sz;
 116 }
 117
 118 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
 119 {
 120         return *get_cpu_ptr(comp->stream);
 121 }
 122
 123 void zcomp_stream_put(struct zcomp *comp)
 124 {
 125         put_cpu_ptr(comp->stream);
 126 }
 127
 128 int zcomp_compress(struct zcomp_strm *zstrm,
 129                 const void *src, unsigned int *dst_len)
 130 {
 131         /*
 132          * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
 133          * because sometimes we can endup having a bigger compressed data
 134          * due to various reasons: for example compression algorithms tend
 135          * to add some padding to the compressed buffer. Speaking of padding,
 136          * comp algorithm `842' pads the compressed length to multiple of 8
 137          * and returns -ENOSP when the dst memory is not big enough, which
 138          * is not something that ZRAM wants to see. We can handle the
 139          * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
 140          * receive -ERRNO from the compressing backend we can't help it
 141          * anymore. To make `842' happy we need to tell the exact size of
 142          * the dst buffer, zram_drv will take care of the fact that
 143          * compressed buffer is too big.
 144          */
 145         *dst_len = PAGE_SIZE * 2;
 146
 147         return crypto_comp_compress(zstrm->tfm,
 148                         src, PAGE_SIZE,
 149                         zstrm->buffer, dst_len);
 150 }
 151
 152 int zcomp_decompress(struct zcomp_strm *zstrm,
 153                 const void *src, unsigned int src_len, void *dst)
 154 {
 155         unsigned int dst_len = PAGE_SIZE;
 156
 157         return crypto_comp_decompress(zstrm->tfm,
 158                         src, src_len,
 159                         dst, &dst_len);
 160 }
 161
 162 int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
 163 {
 164         struct zcomp *comp = hlist_entry(node, struct zcomp, node);
 165         struct zcomp_strm *zstrm;
 166
 167         if (WARN_ON(*per_cpu_ptr(comp->stream, cpu)))
 168                 return 0;
 169
 170         zstrm = zcomp_strm_alloc(comp);
 171         if (IS_ERR_OR_NULL(zstrm)) {
 172                 pr_err("Can't allocate a compression stream\n");
 173                 return -ENOMEM;
 174         }
 175         *per_cpu_ptr(comp->stream, cpu) = zstrm;
 176         return 0;
 177 }
 178
 179 int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
 180 {
 181         struct zcomp *comp = hlist_entry(node, struct zcomp, node);
 182         struct zcomp_strm *zstrm;
 183
 184         zstrm = *per_cpu_ptr(comp->stream, cpu);
 185         if (!IS_ERR_OR_NULL(zstrm))
 186                 zcomp_strm_free(zstrm);
 187         *per_cpu_ptr(comp->stream, cpu) = NULL;
 188         return 0;
 189 }
 190
 191 static int zcomp_init(struct zcomp *comp)
 192 {
 193         int ret;
 194
 195         comp->stream = alloc_percpu(struct zcomp_strm *);
 196         if (!comp->stream)
 197                 return -ENOMEM;
 198
 199         ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
 200         if (ret < 0)
 201                 goto cleanup;
 202         return 0;
 203
 204 cleanup:
 205         free_percpu(comp->stream);
 206         return ret;
 207 }
 208
 209 void zcomp_destroy(struct zcomp *comp)
 210 {
 211         cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
 212         free_percpu(comp->stream);
 213         kfree(comp);
 214 }
 215
 216 /*
 217  * search available compressors for requested algorithm.
 218  * allocate new zcomp and initialize it. return compressing
 219  * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
 220  * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
 221  * case of allocation error, or any other error potentially
 222  * returned by zcomp_init().
 223  */
 224 struct zcomp *zcomp_create(const char *compress)
 225 {
 226         struct zcomp *comp;
 227         int error;
 228
 229         if (!zcomp_available_algorithm(compress))
 230                 return ERR_PTR(-EINVAL);
 231
 232         comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
 233         if (!comp)
 234                 return ERR_PTR(-ENOMEM);
 235
 236         comp->name = compress;
 237         error = zcomp_init(comp);
 238         if (error) {
 239                 kfree(comp);
 240                 return ERR_PTR(error);
 241         }
 242         return comp;
 243 }