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TOMOYO Linux Cross Reference
Linux/fs/jffs2/compr.c

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  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);
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);
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);
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 }
361 

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