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/slab.h>
  13 #include <linux/wait.h>
  14 #include <linux/sched.h>
  15
  16 #include "zcomp.h"
  17 #include "zcomp_lzo.h"
  18 #ifdef CONFIG_ZRAM_LZ4_COMPRESS
  19 #include "zcomp_lz4.h"
  20 #endif
  21
  22 /*
  23  * single zcomp_strm backend
  24  */
  25 struct zcomp_strm_single {
  26         struct mutex strm_lock;
  27         struct zcomp_strm *zstrm;
  28 };
  29
  30 /*
  31  * multi zcomp_strm backend
  32  */
  33 struct zcomp_strm_multi {
  34         /* protect strm list */
  35         spinlock_t strm_lock;
  36         /* max possible number of zstrm streams */
  37         int max_strm;
  38         /* number of available zstrm streams */
  39         int avail_strm;
  40         /* list of available strms */
  41         struct list_head idle_strm;
  42         wait_queue_head_t strm_wait;
  43 };
  44
  45 static struct zcomp_backend *backends[] = {
  46         &zcomp_lzo,
  47 #ifdef CONFIG_ZRAM_LZ4_COMPRESS
  48         &zcomp_lz4,
  49 #endif
  50         NULL
  51 };
  52
  53 static struct zcomp_backend *find_backend(const char *compress)
  54 {
  55         int i = 0;
  56         while (backends[i]) {
  57                 if (sysfs_streq(compress, backends[i]->name))
  58                         break;
  59                 i++;
  60         }
  61         return backends[i];
  62 }
  63
  64 static void zcomp_strm_free(struct zcomp *comp, struct zcomp_strm *zstrm)
  65 {
  66         if (zstrm->private)
  67                 comp->backend->destroy(zstrm->private);
  68         free_pages((unsigned long)zstrm->buffer, 1);
  69         kfree(zstrm);
  70 }
  71
  72 /*
  73  * allocate new zcomp_strm structure with ->private initialized by
  74  * backend, return NULL on error
  75  */
  76 static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
  77 {
  78         struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
  79         if (!zstrm)
  80                 return NULL;
  81
  82         zstrm->private = comp->backend->create();
  83         /*
  84          * allocate 2 pages. 1 for compressed data, plus 1 extra for the
  85          * case when compressed size is larger than the original one
  86          */
  87         zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
  88         if (!zstrm->private || !zstrm->buffer) {
  89                 zcomp_strm_free(comp, zstrm);
  90                 zstrm = NULL;
  91         }
  92         return zstrm;
  93 }
  94
  95 /*
  96  * get idle zcomp_strm or wait until other process release
  97  * (zcomp_strm_release()) one for us
  98  */
  99 static struct zcomp_strm *zcomp_strm_multi_find(struct zcomp *comp)
 100 {
 101         struct zcomp_strm_multi *zs = comp->stream;
 102         struct zcomp_strm *zstrm;
 103
 104         while (1) {
 105                 spin_lock(&zs->strm_lock);
 106                 if (!list_empty(&zs->idle_strm)) {
 107                         zstrm = list_entry(zs->idle_strm.next,
 108                                         struct zcomp_strm, list);
 109                         list_del(&zstrm->list);
 110                         spin_unlock(&zs->strm_lock);
 111                         return zstrm;
 112                 }
 113                 /* zstrm streams limit reached, wait for idle stream */
 114                 if (zs->avail_strm >= zs->max_strm) {
 115                         spin_unlock(&zs->strm_lock);
 116                         wait_event(zs->strm_wait, !list_empty(&zs->idle_strm));
 117                         continue;
 118                 }
 119                 /* allocate new zstrm stream */
 120                 zs->avail_strm++;
 121                 spin_unlock(&zs->strm_lock);
 122
 123                 zstrm = zcomp_strm_alloc(comp);
 124                 if (!zstrm) {
 125                         spin_lock(&zs->strm_lock);
 126                         zs->avail_strm--;
 127                         spin_unlock(&zs->strm_lock);
 128                         wait_event(zs->strm_wait, !list_empty(&zs->idle_strm));
 129                         continue;
 130                 }
 131                 break;
 132         }
 133         return zstrm;
 134 }
 135
 136 /* add stream back to idle list and wake up waiter or free the stream */
 137 static void zcomp_strm_multi_release(struct zcomp *comp, struct zcomp_strm *zstrm)
 138 {
 139         struct zcomp_strm_multi *zs = comp->stream;
 140
 141         spin_lock(&zs->strm_lock);
 142         if (zs->avail_strm <= zs->max_strm) {
 143                 list_add(&zstrm->list, &zs->idle_strm);
 144                 spin_unlock(&zs->strm_lock);
 145                 wake_up(&zs->strm_wait);
 146                 return;
 147         }
 148
 149         zs->avail_strm--;
 150         spin_unlock(&zs->strm_lock);
 151         zcomp_strm_free(comp, zstrm);
 152 }
 153
 154 /* change max_strm limit */
 155 static int zcomp_strm_multi_set_max_streams(struct zcomp *comp, int num_strm)
 156 {
 157         struct zcomp_strm_multi *zs = comp->stream;
 158         struct zcomp_strm *zstrm;
 159
 160         spin_lock(&zs->strm_lock);
 161         zs->max_strm = num_strm;
 162         /*
 163          * if user has lowered the limit and there are idle streams,
 164          * immediately free as much streams (and memory) as we can.
 165          */
 166         while (zs->avail_strm > num_strm && !list_empty(&zs->idle_strm)) {
 167                 zstrm = list_entry(zs->idle_strm.next,
 168                                 struct zcomp_strm, list);
 169                 list_del(&zstrm->list);
 170                 zcomp_strm_free(comp, zstrm);
 171                 zs->avail_strm--;
 172         }
 173         spin_unlock(&zs->strm_lock);
 174         return 0;
 175 }
 176
 177 static void zcomp_strm_multi_destroy(struct zcomp *comp)
 178 {
 179         struct zcomp_strm_multi *zs = comp->stream;
 180         struct zcomp_strm *zstrm;
 181
 182         while (!list_empty(&zs->idle_strm)) {
 183                 zstrm = list_entry(zs->idle_strm.next,
 184                                 struct zcomp_strm, list);
 185                 list_del(&zstrm->list);
 186                 zcomp_strm_free(comp, zstrm);
 187         }
 188         kfree(zs);
 189 }
 190
 191 static int zcomp_strm_multi_create(struct zcomp *comp, int max_strm)
 192 {
 193         struct zcomp_strm *zstrm;
 194         struct zcomp_strm_multi *zs;
 195
 196         comp->destroy = zcomp_strm_multi_destroy;
 197         comp->strm_find = zcomp_strm_multi_find;
 198         comp->strm_release = zcomp_strm_multi_release;
 199         comp->set_max_streams = zcomp_strm_multi_set_max_streams;
 200         zs = kmalloc(sizeof(struct zcomp_strm_multi), GFP_KERNEL);
 201         if (!zs)
 202                 return -ENOMEM;
 203
 204         comp->stream = zs;
 205         spin_lock_init(&zs->strm_lock);
 206         INIT_LIST_HEAD(&zs->idle_strm);
 207         init_waitqueue_head(&zs->strm_wait);
 208         zs->max_strm = max_strm;
 209         zs->avail_strm = 1;
 210
 211         zstrm = zcomp_strm_alloc(comp);
 212         if (!zstrm) {
 213                 kfree(zs);
 214                 return -ENOMEM;
 215         }
 216         list_add(&zstrm->list, &zs->idle_strm);
 217         return 0;
 218 }
 219
 220 static struct zcomp_strm *zcomp_strm_single_find(struct zcomp *comp)
 221 {
 222         struct zcomp_strm_single *zs = comp->stream;
 223         mutex_lock(&zs->strm_lock);
 224         return zs->zstrm;
 225 }
 226
 227 static void zcomp_strm_single_release(struct zcomp *comp,
 228                 struct zcomp_strm *zstrm)
 229 {
 230         struct zcomp_strm_single *zs = comp->stream;
 231         mutex_unlock(&zs->strm_lock);
 232 }
 233
 234 static int zcomp_strm_single_set_max_streams(struct zcomp *comp, int num_strm)
 235 {
 236         /* zcomp_strm_single support only max_comp_streams == 1 */
 237         return -ENOTSUPP;
 238 }
 239
 240 static void zcomp_strm_single_destroy(struct zcomp *comp)
 241 {
 242         struct zcomp_strm_single *zs = comp->stream;
 243         zcomp_strm_free(comp, zs->zstrm);
 244         kfree(zs);
 245 }
 246
 247 static int zcomp_strm_single_create(struct zcomp *comp)
 248 {
 249         struct zcomp_strm_single *zs;
 250
 251         comp->destroy = zcomp_strm_single_destroy;
 252         comp->strm_find = zcomp_strm_single_find;
 253         comp->strm_release = zcomp_strm_single_release;
 254         comp->set_max_streams = zcomp_strm_single_set_max_streams;
 255         zs = kmalloc(sizeof(struct zcomp_strm_single), GFP_KERNEL);
 256         if (!zs)
 257                 return -ENOMEM;
 258
 259         comp->stream = zs;
 260         mutex_init(&zs->strm_lock);
 261         zs->zstrm = zcomp_strm_alloc(comp);
 262         if (!zs->zstrm) {
 263                 kfree(zs);
 264                 return -ENOMEM;
 265         }
 266         return 0;
 267 }
 268
 269 /* show available compressors */
 270 ssize_t zcomp_available_show(const char *comp, char *buf)
 271 {
 272         ssize_t sz = 0;
 273         int i = 0;
 274
 275         while (backends[i]) {
 276                 if (sysfs_streq(comp, backends[i]->name))
 277                         sz += sprintf(buf + sz, "[%s] ", backends[i]->name);
 278                 else
 279                         sz += sprintf(buf + sz, "%s ", backends[i]->name);
 280                 i++;
 281         }
 282         sz += sprintf(buf + sz, "\n");
 283         return sz;
 284 }
 285
 286 int zcomp_set_max_streams(struct zcomp *comp, int num_strm)
 287 {
 288         return comp->set_max_streams(comp, num_strm);
 289 }
 290
 291 struct zcomp_strm *zcomp_strm_find(struct zcomp *comp)
 292 {
 293         return comp->strm_find(comp);
 294 }
 295
 296 void zcomp_strm_release(struct zcomp *comp, struct zcomp_strm *zstrm)
 297 {
 298         comp->strm_release(comp, zstrm);
 299 }
 300
 301 int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
 302                 const unsigned char *src, size_t *dst_len)
 303 {
 304         return comp->backend->compress(src, zstrm->buffer, dst_len,
 305                         zstrm->private);
 306 }
 307
 308 int zcomp_decompress(struct zcomp *comp, const unsigned char *src,
 309                 size_t src_len, unsigned char *dst)
 310 {
 311         return comp->backend->decompress(src, src_len, dst);
 312 }
 313
 314 void zcomp_destroy(struct zcomp *comp)
 315 {
 316         comp->destroy(comp);
 317         kfree(comp);
 318 }
 319
 320 /*
 321  * search available compressors for requested algorithm.
 322  * allocate new zcomp and initialize it. return NULL
 323  * if requested algorithm is not supported or in case
 324  * of init error
 325  */
 326 struct zcomp *zcomp_create(const char *compress, int max_strm)
 327 {
 328         struct zcomp *comp;
 329         struct zcomp_backend *backend;
 330
 331         backend = find_backend(compress);
 332         if (!backend)
 333                 return NULL;
 334
 335         comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
 336         if (!comp)
 337                 return NULL;
 338
 339         comp->backend = backend;
 340         if (max_strm > 1)
 341                 zcomp_strm_multi_create(comp, max_strm);
 342         else
 343                 zcomp_strm_single_create(comp);
 344         if (!comp->stream) {
 345                 kfree(comp);
 346                 return NULL;
 347         }
 348         return comp;
 349 }