fs/jffs2/compr.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright © 2001-2007 Red Hat, Inc.
   5  * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
   6  * Copyright © 2004 Ferenc Havasi <havasi@inf.u-szeged.hu>,
   7  *                  University of Szeged, Hungary
   8  *
   9  * Created by Arjan van de Ven <arjan@infradead.org>
  10  *
  11  * For licensing information, see the file 'LICENCE' in this directory.
  12  *
  13  */
  14
  15 #include "compr.h"
  16
  17 static DEFINE_SPINLOCK(jffs2_compressor_list_lock);
  18
  19 /* Available compressors are on this list */
  20 static LIST_HEAD(jffs2_compressor_list);
  21
  22 /* Actual compression mode */
  23 static int jffs2_compression_mode = JFFS2_COMPR_MODE_PRIORITY;
  24
  25 /* Statistics for blocks stored without compression */
  26 static uint32_t none_stat_compr_blocks=0,none_stat_decompr_blocks=0,none_stat_compr_size=0;
  27
  28
  29 /*
  30  * Return 1 to use this compression
  31  */
  32 static int jffs2_is_best_compression(struct jffs2_compressor *this,
  33                 struct jffs2_compressor *best, uint32_t size, uint32_t bestsize)
  34 {
  35         switch (jffs2_compression_mode) {
  36         case JFFS2_COMPR_MODE_SIZE:
  37                 if (bestsize > size)
  38                         return 1;
  39                 return 0;
  40         case JFFS2_COMPR_MODE_FAVOURLZO:
  41                 if ((this->compr == JFFS2_COMPR_LZO) && (bestsize > size))
  42                         return 1;
  43                 if ((best->compr != JFFS2_COMPR_LZO) && (bestsize > size))
  44                         return 1;
  45                 if ((this->compr == JFFS2_COMPR_LZO) && (bestsize > (size * FAVOUR_LZO_PERCENT / 100)))
  46                         return 1;
  47                 if ((bestsize * FAVOUR_LZO_PERCENT / 100) > size)
  48                         return 1;
  49
  50                 return 0;
  51         }
  52         /* Shouldn't happen */
  53         return 0;
  54 }
  55
  56 /*
  57  * jffs2_selected_compress:
  58  * @compr: Explicit compression type to use (ie, JFFS2_COMPR_ZLIB).
  59  *      If 0, just take the first available compression mode.
  60  * @data_in: Pointer to uncompressed data
  61  * @cpage_out: Pointer to returned pointer to buffer for compressed data
  62  * @datalen: On entry, holds the amount of data available for compression.
  63  *      On exit, expected to hold the amount of data actually compressed.
  64  * @cdatalen: On entry, holds the amount of space available for compressed
  65  *      data. On exit, expected to hold the actual size of the compressed
  66  *      data.
  67  *
  68  * Returns: the compression type used.  Zero is used to show that the data
  69  * could not be compressed; probably because we couldn't find the requested
  70  * compression mode.
  71  */
  72 static int jffs2_selected_compress(u8 compr, unsigned char *data_in,
  73                 unsigned char **cpage_out, u32 *datalen, u32 *cdatalen)
  74 {
  75         struct jffs2_compressor *this;
  76         int err, ret = JFFS2_COMPR_NONE;
  77         uint32_t orig_slen, orig_dlen;
  78         char *output_buf;
  79
  80         output_buf = kmalloc(*cdatalen, GFP_KERNEL);
  81         if (!output_buf) {
  82                 printk(KERN_WARNING "JFFS2: No memory for compressor allocation. Compression failed.\n");
  83                 return ret;
  84         }
  85         orig_slen = *datalen;
  86         orig_dlen = *cdatalen;
  87         spin_lock(&jffs2_compressor_list_lock);
  88         list_for_each_entry(this, &jffs2_compressor_list, list) {
  89                 /* Skip decompress-only and disabled modules */
  90                 if (!this->compress || this->disabled)
  91                         continue;
  92
  93                 /* Skip if not the desired compression type */
  94                 if (compr && (compr != this->compr))
  95                         continue;
  96
  97                 /*
  98                  * Either compression type was unspecified, or we found our
  99                  * compressor; either way, we're good to go.
 100                  */
 101                 this->usecount++;
 102                 spin_unlock(&jffs2_compressor_list_lock);
 103
 104                 *datalen  = orig_slen;
 105                 *cdatalen = orig_dlen;
 106                 err = this->compress(data_in, output_buf, datalen, cdatalen);
 107
 108                 spin_lock(&jffs2_compressor_list_lock);
 109                 this->usecount--;
 110                 if (!err) {
 111                         /* Success */
 112                         ret = this->compr;
 113                         this->stat_compr_blocks++;
 114                         this->stat_compr_orig_size += *datalen;
 115                         this->stat_compr_new_size += *cdatalen;
 116                         break;
 117                 }
 118         }
 119         spin_unlock(&jffs2_compressor_list_lock);
 120         if (ret == JFFS2_COMPR_NONE)
 121                 kfree(output_buf);
 122         else
 123                 *cpage_out = output_buf;
 124
 125         return ret;
 126 }
 127
 128 /* jffs2_compress:
 129  * @data_in: Pointer to uncompressed data
 130  * @cpage_out: Pointer to returned pointer to buffer for compressed data
 131  * @datalen: On entry, holds the amount of data available for compression.
 132  *      On exit, expected to hold the amount of data actually compressed.
 133  * @cdatalen: On entry, holds the amount of space available for compressed
 134  *      data. On exit, expected to hold the actual size of the compressed
 135  *      data.
 136  *
 137  * Returns: Lower byte to be stored with data indicating compression type used.
 138  * Zero is used to show that the data could not be compressed - the
 139  * compressed version was actually larger than the original.
 140  * Upper byte will be used later. (soon)
 141  *
 142  * If the cdata buffer isn't large enough to hold all the uncompressed data,
 143  * jffs2_compress should compress as much as will fit, and should set
 144  * *datalen accordingly to show the amount of data which were compressed.
 145  */
 146 uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 147                         unsigned char *data_in, unsigned char **cpage_out,
 148                         uint32_t *datalen, uint32_t *cdatalen)
 149 {
 150         int ret = JFFS2_COMPR_NONE;
 151         int mode, compr_ret;
 152         struct jffs2_compressor *this, *best=NULL;
 153         unsigned char *output_buf = NULL, *tmp_buf;
 154         uint32_t orig_slen, orig_dlen;
 155         uint32_t best_slen=0, best_dlen=0;
 156
 157         if (c->mount_opts.override_compr)
 158                 mode = c->mount_opts.compr;
 159         else
 160                 mode = jffs2_compression_mode;
 161
 162         switch (mode) {
 163         case JFFS2_COMPR_MODE_NONE:
 164                 break;
 165         case JFFS2_COMPR_MODE_PRIORITY:
 166                 ret = jffs2_selected_compress(0, data_in, cpage_out, datalen,
 167                                 cdatalen);
 168                 break;
 169         case JFFS2_COMPR_MODE_SIZE:
 170         case JFFS2_COMPR_MODE_FAVOURLZO:
 171                 orig_slen = *datalen;
 172                 orig_dlen = *cdatalen;
 173                 spin_lock(&jffs2_compressor_list_lock);
 174                 list_for_each_entry(this, &jffs2_compressor_list, list) {
 175                         /* Skip decompress-only backwards-compatibility and disabled modules */
 176                         if ((!this->compress)||(this->disabled))
 177                                 continue;
 178                         /* Allocating memory for output buffer if necessary */
 179                         if ((this->compr_buf_size < orig_slen) && (this->compr_buf)) {
 180                                 spin_unlock(&jffs2_compressor_list_lock);
 181                                 kfree(this->compr_buf);
 182                                 spin_lock(&jffs2_compressor_list_lock);
 183                                 this->compr_buf_size=0;
 184                                 this->compr_buf=NULL;
 185                         }
 186                         if (!this->compr_buf) {
 187                                 spin_unlock(&jffs2_compressor_list_lock);
 188                                 tmp_buf = kmalloc(orig_slen, GFP_KERNEL);
 189                                 spin_lock(&jffs2_compressor_list_lock);
 190                                 if (!tmp_buf) {
 191                                         printk(KERN_WARNING "JFFS2: No memory for compressor allocation. (%d bytes)\n", orig_slen);
 192                                         continue;
 193                                 }
 194                                 else {
 195                                         this->compr_buf = tmp_buf;
 196                                         this->compr_buf_size = orig_slen;
 197                                 }
 198                         }
 199                         this->usecount++;
 200                         spin_unlock(&jffs2_compressor_list_lock);
 201                         *datalen  = orig_slen;
 202                         *cdatalen = orig_dlen;
 203                         compr_ret = this->compress(data_in, this->compr_buf, datalen, cdatalen);
 204                         spin_lock(&jffs2_compressor_list_lock);
 205                         this->usecount--;
 206                         if (!compr_ret) {
 207                                 if (((!best_dlen) || jffs2_is_best_compression(this, best, *cdatalen, best_dlen))
 208                                                 && (*cdatalen < *datalen)) {
 209                                         best_dlen = *cdatalen;
 210                                         best_slen = *datalen;
 211                                         best = this;
 212                                 }
 213                         }
 214                 }
 215                 if (best_dlen) {
 216                         *cdatalen = best_dlen;
 217                         *datalen  = best_slen;
 218                         output_buf = best->compr_buf;
 219                         best->compr_buf = NULL;
 220                         best->compr_buf_size = 0;
 221                         best->stat_compr_blocks++;
 222                         best->stat_compr_orig_size += best_slen;
 223                         best->stat_compr_new_size  += best_dlen;
 224                         ret = best->compr;
 225                         *cpage_out = output_buf;
 226                 }
 227                 spin_unlock(&jffs2_compressor_list_lock);
 228                 break;
 229         case JFFS2_COMPR_MODE_FORCELZO:
 230                 ret = jffs2_selected_compress(JFFS2_COMPR_LZO, data_in,
 231                                 cpage_out, datalen, cdatalen);
 232                 break;
 233         case JFFS2_COMPR_MODE_FORCEZLIB:
 234                 ret = jffs2_selected_compress(JFFS2_COMPR_ZLIB, data_in,
 235                                 cpage_out, datalen, cdatalen);
 236                 break;
 237         default:
 238                 printk(KERN_ERR "JFFS2: unknown compression mode.\n");
 239         }
 240
 241         if (ret == JFFS2_COMPR_NONE) {
 242                 *cpage_out = data_in;
 243                 *datalen = *cdatalen;
 244                 none_stat_compr_blocks++;
 245                 none_stat_compr_size += *datalen;
 246         }
 247         return ret;
 248 }
 249
 250 int jffs2_decompress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 251                      uint16_t comprtype, unsigned char *cdata_in,
 252                      unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)
 253 {
 254         struct jffs2_compressor *this;
 255         int ret;
 256
 257         /* Older code had a bug where it would write non-zero 'usercompr'
 258            fields. Deal with it. */
 259         if ((comprtype & 0xff) <= JFFS2_COMPR_ZLIB)
 260                 comprtype &= 0xff;
 261
 262         switch (comprtype & 0xff) {
 263         case JFFS2_COMPR_NONE:
 264                 /* This should be special-cased elsewhere, but we might as well deal with it */
 265                 memcpy(data_out, cdata_in, datalen);
 266                 none_stat_decompr_blocks++;
 267                 break;
 268         case JFFS2_COMPR_ZERO:
 269                 memset(data_out, 0, datalen);
 270                 break;
 271         default:
 272                 spin_lock(&jffs2_compressor_list_lock);
 273                 list_for_each_entry(this, &jffs2_compressor_list, list) {
 274                         if (comprtype == this->compr) {
 275                                 this->usecount++;
 276                                 spin_unlock(&jffs2_compressor_list_lock);
 277                                 ret = this->decompress(cdata_in, data_out, cdatalen, datalen);
 278                                 spin_lock(&jffs2_compressor_list_lock);
 279                                 if (ret) {
 280                                         printk(KERN_WARNING "Decompressor \"%s\" returned %d\n", this->name, ret);
 281                                 }
 282                                 else {
 283                                         this->stat_decompr_blocks++;
 284                                 }
 285                                 this->usecount--;
 286                                 spin_unlock(&jffs2_compressor_list_lock);
 287                                 return ret;
 288                         }
 289                 }
 290                 printk(KERN_WARNING "JFFS2 compression type 0x%02x not available.\n", comprtype);
 291                 spin_unlock(&jffs2_compressor_list_lock);
 292                 return -EIO;
 293         }
 294         return 0;
 295 }
 296
 297 int jffs2_register_compressor(struct jffs2_compressor *comp)
 298 {
 299         struct jffs2_compressor *this;
 300
 301         if (!comp->name) {
 302                 printk(KERN_WARNING "NULL compressor name at registering JFFS2 compressor. Failed.\n");
 303                 return -1;
 304         }
 305         comp->compr_buf_size=0;
 306         comp->compr_buf=NULL;
 307         comp->usecount=0;
 308         comp->stat_compr_orig_size=0;
 309         comp->stat_compr_new_size=0;
 310         comp->stat_compr_blocks=0;
 311         comp->stat_decompr_blocks=0;
 312         D1(printk(KERN_DEBUG "Registering JFFS2 compressor \"%s\"\n", comp->name));
 313
 314         spin_lock(&jffs2_compressor_list_lock);
 315
 316         list_for_each_entry(this, &jffs2_compressor_list, list) {
 317                 if (this->priority < comp->priority) {
 318                         list_add(&comp->list, this->list.prev);
 319                         goto out;
 320                 }
 321         }
 322         list_add_tail(&comp->list, &jffs2_compressor_list);
 323 out:
 324         D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
 325                 printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
 326         })
 327
 328         spin_unlock(&jffs2_compressor_list_lock);
 329
 330         return 0;
 331 }
 332
 333 int jffs2_unregister_compressor(struct jffs2_compressor *comp)
 334 {
 335         D2(struct jffs2_compressor *this;)
 336
 337         D1(printk(KERN_DEBUG "Unregistering JFFS2 compressor \"%s\"\n", comp->name));
 338
 339         spin_lock(&jffs2_compressor_list_lock);
 340
 341         if (comp->usecount) {
 342                 spin_unlock(&jffs2_compressor_list_lock);
 343                 printk(KERN_WARNING "JFFS2: Compressor module is in use. Unregister failed.\n");
 344                 return -1;
 345         }
 346         list_del(&comp->list);
 347
 348         D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
 349                 printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
 350         })
 351         spin_unlock(&jffs2_compressor_list_lock);
 352         return 0;
 353 }
 354
 355 void jffs2_free_comprbuf(unsigned char *comprbuf, unsigned char *orig)
 356 {
 357         if (orig != comprbuf)
 358                 kfree(comprbuf);
 359 }
 360
 361 int __init jffs2_compressors_init(void)
 362 {
 363 /* Registering compressors */
 364 #ifdef CONFIG_JFFS2_ZLIB
 365         jffs2_zlib_init();
 366 #endif
 367 #ifdef CONFIG_JFFS2_RTIME
 368         jffs2_rtime_init();
 369 #endif
 370 #ifdef CONFIG_JFFS2_RUBIN
 371         jffs2_rubinmips_init();
 372         jffs2_dynrubin_init();
 373 #endif
 374 #ifdef CONFIG_JFFS2_LZO
 375         jffs2_lzo_init();
 376 #endif
 377 /* Setting default compression mode */
 378 #ifdef CONFIG_JFFS2_CMODE_NONE
 379         jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;
 380         D1(printk(KERN_INFO "JFFS2: default compression mode: none\n");)
 381 #else
 382 #ifdef CONFIG_JFFS2_CMODE_SIZE
 383         jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;
 384         D1(printk(KERN_INFO "JFFS2: default compression mode: size\n");)
 385 #else
 386 #ifdef CONFIG_JFFS2_CMODE_FAVOURLZO
 387         jffs2_compression_mode = JFFS2_COMPR_MODE_FAVOURLZO;
 388         D1(printk(KERN_INFO "JFFS2: default compression mode: favourlzo\n");)
 389 #else
 390         D1(printk(KERN_INFO "JFFS2: default compression mode: priority\n");)
 391 #endif
 392 #endif
 393 #endif
 394         return 0;
 395 }
 396
 397 int jffs2_compressors_exit(void)
 398 {
 399 /* Unregistering compressors */
 400 #ifdef CONFIG_JFFS2_LZO
 401         jffs2_lzo_exit();
 402 #endif
 403 #ifdef CONFIG_JFFS2_RUBIN
 404         jffs2_dynrubin_exit();
 405         jffs2_rubinmips_exit();
 406 #endif
 407 #ifdef CONFIG_JFFS2_RTIME
 408         jffs2_rtime_exit();
 409 #endif
 410 #ifdef CONFIG_JFFS2_ZLIB
 411         jffs2_zlib_exit();
 412 #endif
 413         return 0;
 414 }