fs/jffs2/compr.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright © 2001-2007 Red Hat, Inc.
   5  * Created by Arjan van de Ven <arjanv@redhat.com>
   6  *
   7  * Copyright © 2004 Ferenc Havasi <havasi@inf.u-szeged.hu>,
   8  *                  University of Szeged, Hungary
   9  *
  10  * For licensing information, see the file 'LICENCE' in this directory.
  11  *
  12  */
  13
  14 #include "compr.h"
  15
  16 static DEFINE_SPINLOCK(jffs2_compressor_list_lock);
  17
  18 /* Available compressors are on this list */
  19 static LIST_HEAD(jffs2_compressor_list);
  20
  21 /* Actual compression mode */
  22 static int jffs2_compression_mode = JFFS2_COMPR_MODE_PRIORITY;
  23
  24 /* Statistics for blocks stored without compression */
  25 static uint32_t none_stat_compr_blocks=0,none_stat_decompr_blocks=0,none_stat_compr_size=0;
  26
  27
  28 /*
  29  * Return 1 to use this compression
  30  */
  31 static int jffs2_is_best_compression(struct jffs2_compressor *this,
  32                 struct jffs2_compressor *best, uint32_t size, uint32_t bestsize)
  33 {
  34         switch (jffs2_compression_mode) {
  35         case JFFS2_COMPR_MODE_SIZE:
  36                 if (bestsize > size)
  37                         return 1;
  38                 return 0;
  39         case JFFS2_COMPR_MODE_FAVOURLZO:
  40                 if ((this->compr == JFFS2_COMPR_LZO) && (bestsize > size))
  41                         return 1;
  42                 if ((best->compr != JFFS2_COMPR_LZO) && (bestsize > size))
  43                         return 1;
  44                 if ((this->compr == JFFS2_COMPR_LZO) && (bestsize > (size * FAVOUR_LZO_PERCENT / 100)))
  45                         return 1;
  46                 if ((bestsize * FAVOUR_LZO_PERCENT / 100) > size)
  47                         return 1;
  48
  49                 return 0;
  50         }
  51         /* Shouldn't happen */
  52         return 0;
  53 }
  54
  55 /* jffs2_compress:
  56  * @data_in: Pointer to uncompressed data
  57  * @cpage_out: Pointer to returned pointer to buffer for compressed data
  58  * @datalen: On entry, holds the amount of data available for compression.
  59  *      On exit, expected to hold the amount of data actually compressed.
  60  * @cdatalen: On entry, holds the amount of space available for compressed
  61  *      data. On exit, expected to hold the actual size of the compressed
  62  *      data.
  63  *
  64  * Returns: Lower byte to be stored with data indicating compression type used.
  65  * Zero is used to show that the data could not be compressed - the
  66  * compressed version was actually larger than the original.
  67  * Upper byte will be used later. (soon)
  68  *
  69  * If the cdata buffer isn't large enough to hold all the uncompressed data,
  70  * jffs2_compress should compress as much as will fit, and should set
  71  * *datalen accordingly to show the amount of data which were compressed.
  72  */
  73 uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
  74                         unsigned char *data_in, unsigned char **cpage_out,
  75                         uint32_t *datalen, uint32_t *cdatalen)
  76 {
  77         int ret = JFFS2_COMPR_NONE;
  78         int compr_ret;
  79         struct jffs2_compressor *this, *best=NULL;
  80         unsigned char *output_buf = NULL, *tmp_buf;
  81         uint32_t orig_slen, orig_dlen;
  82         uint32_t best_slen=0, best_dlen=0;
  83
  84         switch (jffs2_compression_mode) {
  85         case JFFS2_COMPR_MODE_NONE:
  86                 break;
  87         case JFFS2_COMPR_MODE_PRIORITY:
  88                 output_buf = kmalloc(*cdatalen,GFP_KERNEL);
  89                 if (!output_buf) {
  90                         printk(KERN_WARNING "JFFS2: No memory for compressor allocation. Compression failed.\n");
  91                         goto out;
  92                 }
  93                 orig_slen = *datalen;
  94                 orig_dlen = *cdatalen;
  95                 spin_lock(&jffs2_compressor_list_lock);
  96                 list_for_each_entry(this, &jffs2_compressor_list, list) {
  97                         /* Skip decompress-only backwards-compatibility and disabled modules */
  98                         if ((!this->compress)||(this->disabled))
  99                                 continue;
 100
 101                         this->usecount++;
 102                         spin_unlock(&jffs2_compressor_list_lock);
 103                         *datalen  = orig_slen;
 104                         *cdatalen = orig_dlen;
 105                         compr_ret = this->compress(data_in, output_buf, datalen, cdatalen, NULL);
 106                         spin_lock(&jffs2_compressor_list_lock);
 107                         this->usecount--;
 108                         if (!compr_ret) {
 109                                 ret = this->compr;
 110                                 this->stat_compr_blocks++;
 111                                 this->stat_compr_orig_size += *datalen;
 112                                 this->stat_compr_new_size  += *cdatalen;
 113                                 break;
 114                         }
 115                 }
 116                 spin_unlock(&jffs2_compressor_list_lock);
 117                 if (ret == JFFS2_COMPR_NONE)
 118                         kfree(output_buf);
 119                 break;
 120         case JFFS2_COMPR_MODE_SIZE:
 121         case JFFS2_COMPR_MODE_FAVOURLZO:
 122                 orig_slen = *datalen;
 123                 orig_dlen = *cdatalen;
 124                 spin_lock(&jffs2_compressor_list_lock);
 125                 list_for_each_entry(this, &jffs2_compressor_list, list) {
 126                         /* Skip decompress-only backwards-compatibility and disabled modules */
 127                         if ((!this->compress)||(this->disabled))
 128                                 continue;
 129                         /* Allocating memory for output buffer if necessary */
 130                         if ((this->compr_buf_size < orig_slen) && (this->compr_buf)) {
 131                                 spin_unlock(&jffs2_compressor_list_lock);
 132                                 kfree(this->compr_buf);
 133                                 spin_lock(&jffs2_compressor_list_lock);
 134                                 this->compr_buf_size=0;
 135                                 this->compr_buf=NULL;
 136                         }
 137                         if (!this->compr_buf) {
 138                                 spin_unlock(&jffs2_compressor_list_lock);
 139                                 tmp_buf = kmalloc(orig_slen, GFP_KERNEL);
 140                                 spin_lock(&jffs2_compressor_list_lock);
 141                                 if (!tmp_buf) {
 142                                         printk(KERN_WARNING "JFFS2: No memory for compressor allocation. (%d bytes)\n", orig_slen);
 143                                         continue;
 144                                 }
 145                                 else {
 146                                         this->compr_buf = tmp_buf;
 147                                         this->compr_buf_size = orig_slen;
 148                                 }
 149                         }
 150                         this->usecount++;
 151                         spin_unlock(&jffs2_compressor_list_lock);
 152                         *datalen  = orig_slen;
 153                         *cdatalen = orig_dlen;
 154                         compr_ret = this->compress(data_in, this->compr_buf, datalen, cdatalen, NULL);
 155                         spin_lock(&jffs2_compressor_list_lock);
 156                         this->usecount--;
 157                         if (!compr_ret) {
 158                                 if (((!best_dlen) || jffs2_is_best_compression(this, best, *cdatalen, best_dlen))
 159                                                 && (*cdatalen < *datalen)) {
 160                                         best_dlen = *cdatalen;
 161                                         best_slen = *datalen;
 162                                         best = this;
 163                                 }
 164                         }
 165                 }
 166                 if (best_dlen) {
 167                         *cdatalen = best_dlen;
 168                         *datalen  = best_slen;
 169                         output_buf = best->compr_buf;
 170                         best->compr_buf = NULL;
 171                         best->compr_buf_size = 0;
 172                         best->stat_compr_blocks++;
 173                         best->stat_compr_orig_size += best_slen;
 174                         best->stat_compr_new_size  += best_dlen;
 175                         ret = best->compr;
 176                 }
 177                 spin_unlock(&jffs2_compressor_list_lock);
 178                 break;
 179         default:
 180                 printk(KERN_ERR "JFFS2: unknow compression mode.\n");
 181         }
 182  out:
 183         if (ret == JFFS2_COMPR_NONE) {
 184                 *cpage_out = data_in;
 185                 *datalen = *cdatalen;
 186                 none_stat_compr_blocks++;
 187                 none_stat_compr_size += *datalen;
 188         }
 189         else {
 190                 *cpage_out = output_buf;
 191         }
 192         return ret;
 193 }
 194
 195 int jffs2_decompress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 196                      uint16_t comprtype, unsigned char *cdata_in,
 197                      unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)
 198 {
 199         struct jffs2_compressor *this;
 200         int ret;
 201
 202         /* Older code had a bug where it would write non-zero 'usercompr'
 203            fields. Deal with it. */
 204         if ((comprtype & 0xff) <= JFFS2_COMPR_ZLIB)
 205                 comprtype &= 0xff;
 206
 207         switch (comprtype & 0xff) {
 208         case JFFS2_COMPR_NONE:
 209                 /* This should be special-cased elsewhere, but we might as well deal with it */
 210                 memcpy(data_out, cdata_in, datalen);
 211                 none_stat_decompr_blocks++;
 212                 break;
 213         case JFFS2_COMPR_ZERO:
 214                 memset(data_out, 0, datalen);
 215                 break;
 216         default:
 217                 spin_lock(&jffs2_compressor_list_lock);
 218                 list_for_each_entry(this, &jffs2_compressor_list, list) {
 219                         if (comprtype == this->compr) {
 220                                 this->usecount++;
 221                                 spin_unlock(&jffs2_compressor_list_lock);
 222                                 ret = this->decompress(cdata_in, data_out, cdatalen, datalen, NULL);
 223                                 spin_lock(&jffs2_compressor_list_lock);
 224                                 if (ret) {
 225                                         printk(KERN_WARNING "Decompressor \"%s\" returned %d\n", this->name, ret);
 226                                 }
 227                                 else {
 228                                         this->stat_decompr_blocks++;
 229                                 }
 230                                 this->usecount--;
 231                                 spin_unlock(&jffs2_compressor_list_lock);
 232                                 return ret;
 233                         }
 234                 }
 235                 printk(KERN_WARNING "JFFS2 compression type 0x%02x not available.\n", comprtype);
 236                 spin_unlock(&jffs2_compressor_list_lock);
 237                 return -EIO;
 238         }
 239         return 0;
 240 }
 241
 242 int jffs2_register_compressor(struct jffs2_compressor *comp)
 243 {
 244         struct jffs2_compressor *this;
 245
 246         if (!comp->name) {
 247                 printk(KERN_WARNING "NULL compressor name at registering JFFS2 compressor. Failed.\n");
 248                 return -1;
 249         }
 250         comp->compr_buf_size=0;
 251         comp->compr_buf=NULL;
 252         comp->usecount=0;
 253         comp->stat_compr_orig_size=0;
 254         comp->stat_compr_new_size=0;
 255         comp->stat_compr_blocks=0;
 256         comp->stat_decompr_blocks=0;
 257         D1(printk(KERN_DEBUG "Registering JFFS2 compressor \"%s\"\n", comp->name));
 258
 259         spin_lock(&jffs2_compressor_list_lock);
 260
 261         list_for_each_entry(this, &jffs2_compressor_list, list) {
 262                 if (this->priority < comp->priority) {
 263                         list_add(&comp->list, this->list.prev);
 264                         goto out;
 265                 }
 266         }
 267         list_add_tail(&comp->list, &jffs2_compressor_list);
 268 out:
 269         D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
 270                 printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
 271         })
 272
 273         spin_unlock(&jffs2_compressor_list_lock);
 274
 275         return 0;
 276 }
 277
 278 int jffs2_unregister_compressor(struct jffs2_compressor *comp)
 279 {
 280         D2(struct jffs2_compressor *this;)
 281
 282         D1(printk(KERN_DEBUG "Unregistering JFFS2 compressor \"%s\"\n", comp->name));
 283
 284         spin_lock(&jffs2_compressor_list_lock);
 285
 286         if (comp->usecount) {
 287                 spin_unlock(&jffs2_compressor_list_lock);
 288                 printk(KERN_WARNING "JFFS2: Compressor modul is in use. Unregister failed.\n");
 289                 return -1;
 290         }
 291         list_del(&comp->list);
 292
 293         D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
 294                 printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
 295         })
 296         spin_unlock(&jffs2_compressor_list_lock);
 297         return 0;
 298 }
 299
 300 void jffs2_free_comprbuf(unsigned char *comprbuf, unsigned char *orig)
 301 {
 302         if (orig != comprbuf)
 303                 kfree(comprbuf);
 304 }
 305
 306 int __init jffs2_compressors_init(void)
 307 {
 308 /* Registering compressors */
 309 #ifdef CONFIG_JFFS2_ZLIB
 310         jffs2_zlib_init();
 311 #endif
 312 #ifdef CONFIG_JFFS2_RTIME
 313         jffs2_rtime_init();
 314 #endif
 315 #ifdef CONFIG_JFFS2_RUBIN
 316         jffs2_rubinmips_init();
 317         jffs2_dynrubin_init();
 318 #endif
 319 #ifdef CONFIG_JFFS2_LZO
 320         jffs2_lzo_init();
 321 #endif
 322 /* Setting default compression mode */
 323 #ifdef CONFIG_JFFS2_CMODE_NONE
 324         jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;
 325         D1(printk(KERN_INFO "JFFS2: default compression mode: none\n");)
 326 #else
 327 #ifdef CONFIG_JFFS2_CMODE_SIZE
 328         jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;
 329         D1(printk(KERN_INFO "JFFS2: default compression mode: size\n");)
 330 #else
 331 #ifdef CONFIG_JFFS2_CMODE_FAVOURLZO
 332         jffs2_compression_mode = JFFS2_COMPR_MODE_FAVOURLZO;
 333         D1(printk(KERN_INFO "JFFS2: default compression mode: favourlzo\n");)
 334 #else
 335         D1(printk(KERN_INFO "JFFS2: default compression mode: priority\n");)
 336 #endif
 337 #endif
 338 #endif
 339         return 0;
 340 }
 341
 342 int jffs2_compressors_exit(void)
 343 {
 344 /* Unregistering compressors */
 345 #ifdef CONFIG_JFFS2_LZO
 346         jffs2_lzo_exit();
 347 #endif
 348 #ifdef CONFIG_JFFS2_RUBIN
 349         jffs2_dynrubin_exit();
 350         jffs2_rubinmips_exit();
 351 #endif
 352 #ifdef CONFIG_JFFS2_RTIME
 353         jffs2_rtime_exit();
 354 #endif
 355 #ifdef CONFIG_JFFS2_ZLIB
 356         jffs2_zlib_exit();
 357 #endif
 358         return 0;
 359 }