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
  17 #include "zcomp.h"
  18 #include "zcomp_lzo.h"
  19 #ifdef CONFIG_ZRAM_LZ4_COMPRESS
  20 #include "zcomp_lz4.h"
  21 #endif
  22
  23 /*
  24  * single zcomp_strm backend
  25  */
  26 struct zcomp_strm_single {
  27         struct mutex strm_lock;
  28         struct zcomp_strm *zstrm;
  29 };
  30
  31 /*
  32  * multi zcomp_strm backend
  33  */
  34 struct zcomp_strm_multi {
  35         /* protect strm list */
  36         spinlock_t strm_lock;
  37         /* max possible number of zstrm streams */
  38         int max_strm;
  39         /* number of available zstrm streams */
  40         int avail_strm;
  41         /* list of available strms */
  42         struct list_head idle_strm;
  43         wait_queue_head_t strm_wait;
  44 };
  45
  46 static struct zcomp_backend *backends[] = {
  47         &zcomp_lzo,
  48 #ifdef CONFIG_ZRAM_LZ4_COMPRESS
  49         &zcomp_lz4,
  50 #endif
  51         NULL
  52 };
  53
  54 static struct zcomp_backend *find_backend(const char *compress)
  55 {
  56         int i = 0;
  57         while (backends[i]) {
  58                 if (sysfs_streq(compress, backends[i]->name))
  59                         break;
  60                 i++;
  61         }
  62         return backends[i];
  63 }
  64
  65 static void zcomp_strm_free(struct zcomp *comp, struct zcomp_strm *zstrm)
  66 {
  67         if (zstrm->private)
  68                 comp->backend->destroy(zstrm->private);
  69         free_pages((unsigned long)zstrm->buffer, 1);
  70         kfree(zstrm);
  71 }
  72
  73 /*
  74  * allocate new zcomp_strm structure with ->private initialized by
  75  * backend, return NULL on error
  76  */
  77 static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
  78 {
  79         struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
  80         if (!zstrm)
  81                 return NULL;
  82
  83         zstrm->private = comp->backend->create();
  84         /*
  85          * allocate 2 pages. 1 for compressed data, plus 1 extra for the
  86          * case when compressed size is larger than the original one
  87          */
  88         zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
  89         if (!zstrm->private || !zstrm->buffer) {
  90                 zcomp_strm_free(comp, zstrm);
  91                 zstrm = NULL;
  92         }
  93         return zstrm;
  94 }
  95
  96 /*
  97  * get idle zcomp_strm or wait until other process release
  98  * (zcomp_strm_release()) one for us
  99  */
 100 static struct zcomp_strm *zcomp_strm_multi_find(struct zcomp *comp)
 101 {
 102         struct zcomp_strm_multi *zs = comp->stream;
 103         struct zcomp_strm *zstrm;
 104
 105         while (1) {
 106                 spin_lock(&zs->strm_lock);
 107                 if (!list_empty(&zs->idle_strm)) {
 108                         zstrm = list_entry(zs->idle_strm.next,
 109                                         struct zcomp_strm, list);
 110                         list_del(&zstrm->list);
 111                         spin_unlock(&zs->strm_lock);
 112                         return zstrm;
 113                 }
 114                 /* zstrm streams limit reached, wait for idle stream */
 115                 if (zs->avail_strm >= zs->max_strm) {
 116                         spin_unlock(&zs->strm_lock);
 117                         wait_event(zs->strm_wait, !list_empty(&zs->idle_strm));
 118                         continue;
 119                 }
 120                 /* allocate new zstrm stream */
 121                 zs->avail_strm++;
 122                 spin_unlock(&zs->strm_lock);
 123
 124                 zstrm = zcomp_strm_alloc(comp);
 125                 if (!zstrm) {
 126                         spin_lock(&zs->strm_lock);
 127                         zs->avail_strm--;
 128                         spin_unlock(&zs->strm_lock);
 129                         wait_event(zs->strm_wait, !list_empty(&zs->idle_strm));
 130                         continue;
 131                 }
 132                 break;
 133         }
 134         return zstrm;
 135 }
 136
 137 /* add stream back to idle list and wake up waiter or free the stream */
 138 static void zcomp_strm_multi_release(struct zcomp *comp, struct zcomp_strm *zstrm)
 139 {
 140         struct zcomp_strm_multi *zs = comp->stream;
 141
 142         spin_lock(&zs->strm_lock);
 143         if (zs->avail_strm <= zs->max_strm) {
 144                 list_add(&zstrm->list, &zs->idle_strm);
 145                 spin_unlock(&zs->strm_lock);
 146                 wake_up(&zs->strm_wait);
 147                 return;
 148         }
 149
 150         zs->avail_strm--;
 151         spin_unlock(&zs->strm_lock);
 152         zcomp_strm_free(comp, zstrm);
 153 }
 154
 155 /* change max_strm limit */
 156 static bool zcomp_strm_multi_set_max_streams(struct zcomp *comp, int num_strm)
 157 {
 158         struct zcomp_strm_multi *zs = comp->stream;
 159         struct zcomp_strm *zstrm;
 160
 161         spin_lock(&zs->strm_lock);
 162         zs->max_strm = num_strm;
 163         /*
 164          * if user has lowered the limit and there are idle streams,
 165          * immediately free as much streams (and memory) as we can.
 166          */
 167         while (zs->avail_strm > num_strm && !list_empty(&zs->idle_strm)) {
 168                 zstrm = list_entry(zs->idle_strm.next,
 169                                 struct zcomp_strm, list);
 170                 list_del(&zstrm->list);
 171                 zcomp_strm_free(comp, zstrm);
 172                 zs->avail_strm--;
 173         }
 174         spin_unlock(&zs->strm_lock);
 175         return true;
 176 }
 177
 178 static void zcomp_strm_multi_destroy(struct zcomp *comp)
 179 {
 180         struct zcomp_strm_multi *zs = comp->stream;
 181         struct zcomp_strm *zstrm;
 182
 183         while (!list_empty(&zs->idle_strm)) {
 184                 zstrm = list_entry(zs->idle_strm.next,
 185                                 struct zcomp_strm, list);
 186                 list_del(&zstrm->list);
 187                 zcomp_strm_free(comp, zstrm);
 188         }
 189         kfree(zs);
 190 }
 191
 192 static int zcomp_strm_multi_create(struct zcomp *comp, int max_strm)
 193 {
 194         struct zcomp_strm *zstrm;
 195         struct zcomp_strm_multi *zs;
 196
 197         comp->destroy = zcomp_strm_multi_destroy;
 198         comp->strm_find = zcomp_strm_multi_find;
 199         comp->strm_release = zcomp_strm_multi_release;
 200         comp->set_max_streams = zcomp_strm_multi_set_max_streams;
 201         zs = kmalloc(sizeof(struct zcomp_strm_multi), GFP_KERNEL);
 202         if (!zs)
 203                 return -ENOMEM;
 204
 205         comp->stream = zs;
 206         spin_lock_init(&zs->strm_lock);
 207         INIT_LIST_HEAD(&zs->idle_strm);
 208         init_waitqueue_head(&zs->strm_wait);
 209         zs->max_strm = max_strm;
 210         zs->avail_strm = 1;
 211
 212         zstrm = zcomp_strm_alloc(comp);
 213         if (!zstrm) {
 214                 kfree(zs);
 215                 return -ENOMEM;
 216         }
 217         list_add(&zstrm->list, &zs->idle_strm);
 218         return 0;
 219 }
 220
 221 static struct zcomp_strm *zcomp_strm_single_find(struct zcomp *comp)
 222 {
 223         struct zcomp_strm_single *zs = comp->stream;
 224         mutex_lock(&zs->strm_lock);
 225         return zs->zstrm;
 226 }
 227
 228 static void zcomp_strm_single_release(struct zcomp *comp,
 229                 struct zcomp_strm *zstrm)
 230 {
 231         struct zcomp_strm_single *zs = comp->stream;
 232         mutex_unlock(&zs->strm_lock);
 233 }
 234
 235 static bool zcomp_strm_single_set_max_streams(struct zcomp *comp, int num_strm)
 236 {
 237         /* zcomp_strm_single support only max_comp_streams == 1 */
 238         return false;
 239 }
 240
 241 static void zcomp_strm_single_destroy(struct zcomp *comp)
 242 {
 243         struct zcomp_strm_single *zs = comp->stream;
 244         zcomp_strm_free(comp, zs->zstrm);
 245         kfree(zs);
 246 }
 247
 248 static int zcomp_strm_single_create(struct zcomp *comp)
 249 {
 250         struct zcomp_strm_single *zs;
 251
 252         comp->destroy = zcomp_strm_single_destroy;
 253         comp->strm_find = zcomp_strm_single_find;
 254         comp->strm_release = zcomp_strm_single_release;
 255         comp->set_max_streams = zcomp_strm_single_set_max_streams;
 256         zs = kmalloc(sizeof(struct zcomp_strm_single), GFP_KERNEL);
 257         if (!zs)
 258                 return -ENOMEM;
 259
 260         comp->stream = zs;
 261         mutex_init(&zs->strm_lock);
 262         zs->zstrm = zcomp_strm_alloc(comp);
 263         if (!zs->zstrm) {
 264                 kfree(zs);
 265                 return -ENOMEM;
 266         }
 267         return 0;
 268 }
 269
 270 /* show available compressors */
 271 ssize_t zcomp_available_show(const char *comp, char *buf)
 272 {
 273         ssize_t sz = 0;
 274         int i = 0;
 275
 276         while (backends[i]) {
 277                 if (!strcmp(comp, backends[i]->name))
 278                         sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
 279                                         "[%s] ", backends[i]->name);
 280                 else
 281                         sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
 282                                         "%s ", backends[i]->name);
 283                 i++;
 284         }
 285         sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
 286         return sz;
 287 }
 288
 289 bool zcomp_available_algorithm(const char *comp)
 290 {
 291         return find_backend(comp) != NULL;
 292 }
 293
 294 bool zcomp_set_max_streams(struct zcomp *comp, int num_strm)
 295 {
 296         return comp->set_max_streams(comp, num_strm);
 297 }
 298
 299 struct zcomp_strm *zcomp_strm_find(struct zcomp *comp)
 300 {
 301         return comp->strm_find(comp);
 302 }
 303
 304 void zcomp_strm_release(struct zcomp *comp, struct zcomp_strm *zstrm)
 305 {
 306         comp->strm_release(comp, zstrm);
 307 }
 308
 309 int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
 310                 const unsigned char *src, size_t *dst_len)
 311 {
 312         return comp->backend->compress(src, zstrm->buffer, dst_len,
 313                         zstrm->private);
 314 }
 315
 316 int zcomp_decompress(struct zcomp *comp, const unsigned char *src,
 317                 size_t src_len, unsigned char *dst)
 318 {
 319         return comp->backend->decompress(src, src_len, dst);
 320 }
 321
 322 void zcomp_destroy(struct zcomp *comp)
 323 {
 324         comp->destroy(comp);
 325         kfree(comp);
 326 }
 327
 328 /*
 329  * search available compressors for requested algorithm.
 330  * allocate new zcomp and initialize it. return compressing
 331  * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
 332  * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
 333  * case of allocation error, or any other error potentially
 334  * returned by functions zcomp_strm_{multi,single}_create.
 335  */
 336 struct zcomp *zcomp_create(const char *compress, int max_strm)
 337 {
 338         struct zcomp *comp;
 339         struct zcomp_backend *backend;
 340         int error;
 341
 342         backend = find_backend(compress);
 343         if (!backend)
 344                 return ERR_PTR(-EINVAL);
 345
 346         comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
 347         if (!comp)
 348                 return ERR_PTR(-ENOMEM);
 349
 350         comp->backend = backend;
 351         if (max_strm > 1)
 352                 error = zcomp_strm_multi_create(comp, max_strm);
 353         else
 354                 error = zcomp_strm_single_create(comp);
 355         if (error) {
 356                 kfree(comp);
 357                 return ERR_PTR(error);
 358         }
 359         return comp;
 360 }