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 /* jffs2_compress:
  57  * @data_in: Pointer to uncompressed data
  58  * @cpage_out: Pointer to returned pointer to buffer for compressed data
  59  * @datalen: On entry, holds the amount of data available for compression.
  60  *      On exit, expected to hold the amount of data actually compressed.
  61  * @cdatalen: On entry, holds the amount of space available for compressed
  62  *      data. On exit, expected to hold the actual size of the compressed
  63  *      data.
  64  *
  65  * Returns: Lower byte to be stored with data indicating compression type used.
  66  * Zero is used to show that the data could not be compressed - the
  67  * compressed version was actually larger than the original.
  68  * Upper byte will be used later. (soon)
  69  *
  70  * If the cdata buffer isn't large enough to hold all the uncompressed data,
  71  * jffs2_compress should compress as much as will fit, and should set
  72  * *datalen accordingly to show the amount of data which were compressed.
  73  */
  74 uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
  75                         unsigned char *data_in, unsigned char **cpage_out,
  76                         uint32_t *datalen, uint32_t *cdatalen)
  77 {
  78         int ret = JFFS2_COMPR_NONE;
  79         int compr_ret;
  80         struct jffs2_compressor *this, *best=NULL;
  81         unsigned char *output_buf = NULL, *tmp_buf;
  82         uint32_t orig_slen, orig_dlen;
  83         uint32_t best_slen=0, best_dlen=0;
  84
  85         switch (jffs2_compression_mode) {
  86         case JFFS2_COMPR_MODE_NONE:
  87                 break;
  88         case JFFS2_COMPR_MODE_PRIORITY:
  89                 output_buf = kmalloc(*cdatalen,GFP_KERNEL);
  90                 if (!output_buf) {
  91                         printk(KERN_WARNING "JFFS2: No memory for compressor allocation. Compression failed.\n");
  92                         goto out;
  93                 }
  94                 orig_slen = *datalen;
  95                 orig_dlen = *cdatalen;
  96                 spin_lock(&jffs2_compressor_list_lock);
  97                 list_for_each_entry(this, &jffs2_compressor_list, list) {
  98                         /* Skip decompress-only backwards-compatibility and disabled modules */
  99                         if ((!this->compress)||(this->disabled))
 100                                 continue;
 101
 102                         this->usecount++;
 103                         spin_unlock(&jffs2_compressor_list_lock);
 104                         *datalen  = orig_slen;
 105                         *cdatalen = orig_dlen;
 106                         compr_ret = this->compress(data_in, output_buf, datalen, cdatalen, NULL);
 107                         spin_lock(&jffs2_compressor_list_lock);
 108                         this->usecount--;
 109                         if (!compr_ret) {
 110                                 ret = this->compr;
 111                                 this->stat_compr_blocks++;
 112                                 this->stat_compr_orig_size += *datalen;
 113                                 this->stat_compr_new_size  += *cdatalen;
 114                                 break;
 115                         }
 116                 }
 117                 spin_unlock(&jffs2_compressor_list_lock);
 118                 if (ret == JFFS2_COMPR_NONE)
 119                         kfree(output_buf);
 120                 break;
 121         case JFFS2_COMPR_MODE_SIZE:
 122         case JFFS2_COMPR_MODE_FAVOURLZO:
 123                 orig_slen = *datalen;
 124                 orig_dlen = *cdatalen;
 125                 spin_lock(&jffs2_compressor_list_lock);
 126                 list_for_each_entry(this, &jffs2_compressor_list, list) {
 127                         /* Skip decompress-only backwards-compatibility and disabled modules */
 128                         if ((!this->compress)||(this->disabled))
 129                                 continue;
 130                         /* Allocating memory for output buffer if necessary */
 131                         if ((this->compr_buf_size < orig_slen) && (this->compr_buf)) {
 132                                 spin_unlock(&jffs2_compressor_list_lock);
 133                                 kfree(this->compr_buf);
 134                                 spin_lock(&jffs2_compressor_list_lock);
 135                                 this->compr_buf_size=0;
 136                                 this->compr_buf=NULL;
 137                         }
 138                         if (!this->compr_buf) {
 139                                 spin_unlock(&jffs2_compressor_list_lock);
 140                                 tmp_buf = kmalloc(orig_slen, GFP_KERNEL);
 141                                 spin_lock(&jffs2_compressor_list_lock);
 142                                 if (!tmp_buf) {
 143                                         printk(KERN_WARNING "JFFS2: No memory for compressor allocation. (%d bytes)\n", orig_slen);
 144                                         continue;
 145                                 }
 146                                 else {
 147                                         this->compr_buf = tmp_buf;
 148                                         this->compr_buf_size = orig_slen;
 149                                 }
 150                         }
 151                         this->usecount++;
 152                         spin_unlock(&jffs2_compressor_list_lock);
 153                         *datalen  = orig_slen;
 154                         *cdatalen = orig_dlen;
 155                         compr_ret = this->compress(data_in, this->compr_buf, datalen, cdatalen, NULL);
 156                         spin_lock(&jffs2_compressor_list_lock);
 157                         this->usecount--;
 158                         if (!compr_ret) {
 159                                 if (((!best_dlen) || jffs2_is_best_compression(this, best, *cdatalen, best_dlen))
 160                                                 && (*cdatalen < *datalen)) {
 161                                         best_dlen = *cdatalen;
 162                                         best_slen = *datalen;
 163                                         best = this;
 164                                 }
 165                         }
 166                 }
 167                 if (best_dlen) {
 168                         *cdatalen = best_dlen;
 169                         *datalen  = best_slen;
 170                         output_buf = best->compr_buf;
 171                         best->compr_buf = NULL;
 172                         best->compr_buf_size = 0;
 173                         best->stat_compr_blocks++;
 174                         best->stat_compr_orig_size += best_slen;
 175                         best->stat_compr_new_size  += best_dlen;
 176                         ret = best->compr;
 177                 }
 178                 spin_unlock(&jffs2_compressor_list_lock);
 179                 break;
 180         default:
 181                 printk(KERN_ERR "JFFS2: unknown compression mode.\n");
 182         }
 183  out:
 184         if (ret == JFFS2_COMPR_NONE) {
 185                 *cpage_out = data_in;
 186                 *datalen = *cdatalen;
 187                 none_stat_compr_blocks++;
 188                 none_stat_compr_size += *datalen;
 189         }
 190         else {
 191                 *cpage_out = output_buf;
 192         }
 193         return ret;
 194 }
 195
 196 int jffs2_decompress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 197                      uint16_t comprtype, unsigned char *cdata_in,
 198                      unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)
 199 {
 200         struct jffs2_compressor *this;
 201         int ret;
 202
 203         /* Older code had a bug where it would write non-zero 'usercompr'
 204            fields. Deal with it. */
 205         if ((comprtype & 0xff) <= JFFS2_COMPR_ZLIB)
 206                 comprtype &= 0xff;
 207
 208         switch (comprtype & 0xff) {
 209         case JFFS2_COMPR_NONE:
 210                 /* This should be special-cased elsewhere, but we might as well deal with it */
 211                 memcpy(data_out, cdata_in, datalen);
 212                 none_stat_decompr_blocks++;
 213                 break;
 214         case JFFS2_COMPR_ZERO:
 215                 memset(data_out, 0, datalen);
 216                 break;
 217         default:
 218                 spin_lock(&jffs2_compressor_list_lock);
 219                 list_for_each_entry(this, &jffs2_compressor_list, list) {
 220                         if (comprtype == this->compr) {
 221                                 this->usecount++;
 222                                 spin_unlock(&jffs2_compressor_list_lock);
 223                                 ret = this->decompress(cdata_in, data_out, cdatalen, datalen, NULL);
 224                                 spin_lock(&jffs2_compressor_list_lock);
 225                                 if (ret) {
 226                                         printk(KERN_WARNING "Decompressor \"%s\" returned %d\n", this->name, ret);
 227                                 }
 228                                 else {
 229                                         this->stat_decompr_blocks++;
 230                                 }
 231                                 this->usecount--;
 232                                 spin_unlock(&jffs2_compressor_list_lock);
 233                                 return ret;
 234                         }
 235                 }
 236                 printk(KERN_WARNING "JFFS2 compression type 0x%02x not available.\n", comprtype);
 237                 spin_unlock(&jffs2_compressor_list_lock);
 238                 return -EIO;
 239         }
 240         return 0;
 241 }
 242
 243 int jffs2_register_compressor(struct jffs2_compressor *comp)
 244 {
 245         struct jffs2_compressor *this;
 246
 247         if (!comp->name) {
 248                 printk(KERN_WARNING "NULL compressor name at registering JFFS2 compressor. Failed.\n");
 249                 return -1;
 250         }
 251         comp->compr_buf_size=0;
 252         comp->compr_buf=NULL;
 253         comp->usecount=0;
 254         comp->stat_compr_orig_size=0;
 255         comp->stat_compr_new_size=0;
 256         comp->stat_compr_blocks=0;
 257         comp->stat_decompr_blocks=0;
 258         D1(printk(KERN_DEBUG "Registering JFFS2 compressor \"%s\"\n", comp->name));
 259
 260         spin_lock(&jffs2_compressor_list_lock);
 261
 262         list_for_each_entry(this, &jffs2_compressor_list, list) {
 263                 if (this->priority < comp->priority) {
 264                         list_add(&comp->list, this->list.prev);
 265                         goto out;
 266                 }
 267         }
 268         list_add_tail(&comp->list, &jffs2_compressor_list);
 269 out:
 270         D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
 271                 printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
 272         })
 273
 274         spin_unlock(&jffs2_compressor_list_lock);
 275
 276         return 0;
 277 }
 278
 279 int jffs2_unregister_compressor(struct jffs2_compressor *comp)
 280 {
 281         D2(struct jffs2_compressor *this;)
 282
 283         D1(printk(KERN_DEBUG "Unregistering JFFS2 compressor \"%s\"\n", comp->name));
 284
 285         spin_lock(&jffs2_compressor_list_lock);
 286
 287         if (comp->usecount) {
 288                 spin_unlock(&jffs2_compressor_list_lock);
 289                 printk(KERN_WARNING "JFFS2: Compressor modul is in use. Unregister failed.\n");
 290                 return -1;
 291         }
 292         list_del(&comp->list);
 293
 294         D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
 295                 printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
 296         })
 297         spin_unlock(&jffs2_compressor_list_lock);
 298         return 0;
 299 }
 300
 301 void jffs2_free_comprbuf(unsigned char *comprbuf, unsigned char *orig)
 302 {
 303         if (orig != comprbuf)
 304                 kfree(comprbuf);
 305 }
 306
 307 int __init jffs2_compressors_init(void)
 308 {
 309 /* Registering compressors */
 310 #ifdef CONFIG_JFFS2_ZLIB
 311         jffs2_zlib_init();
 312 #endif
 313 #ifdef CONFIG_JFFS2_RTIME
 314         jffs2_rtime_init();
 315 #endif
 316 #ifdef CONFIG_JFFS2_RUBIN
 317         jffs2_rubinmips_init();
 318         jffs2_dynrubin_init();
 319 #endif
 320 #ifdef CONFIG_JFFS2_LZO
 321         jffs2_lzo_init();
 322 #endif
 323 /* Setting default compression mode */
 324 #ifdef CONFIG_JFFS2_CMODE_NONE
 325         jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;
 326         D1(printk(KERN_INFO "JFFS2: default compression mode: none\n");)
 327 #else
 328 #ifdef CONFIG_JFFS2_CMODE_SIZE
 329         jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;
 330         D1(printk(KERN_INFO "JFFS2: default compression mode: size\n");)
 331 #else
 332 #ifdef CONFIG_JFFS2_CMODE_FAVOURLZO
 333         jffs2_compression_mode = JFFS2_COMPR_MODE_FAVOURLZO;
 334         D1(printk(KERN_INFO "JFFS2: default compression mode: favourlzo\n");)
 335 #else
 336         D1(printk(KERN_INFO "JFFS2: default compression mode: priority\n");)
 337 #endif
 338 #endif
 339 #endif
 340         return 0;
 341 }
 342
 343 int jffs2_compressors_exit(void)
 344 {
 345 /* Unregistering compressors */
 346 #ifdef CONFIG_JFFS2_LZO
 347         jffs2_lzo_exit();
 348 #endif
 349 #ifdef CONFIG_JFFS2_RUBIN
 350         jffs2_dynrubin_exit();
 351         jffs2_rubinmips_exit();
 352 #endif
 353 #ifdef CONFIG_JFFS2_RTIME
 354         jffs2_rtime_exit();
 355 #endif
 356 #ifdef CONFIG_JFFS2_ZLIB
 357         jffs2_zlib_exit();
 358 #endif
 359         return 0;
 360 }