fs/ubifs/compress.c

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation.
   5  * Copyright (C) 2006, 2007 University of Szeged, Hungary
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 as published by
   9  * the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14  * more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along with
  17  * this program; if not, write to the Free Software Foundation, Inc., 51
  18  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  *
  20  * Authors: Adrian Hunter
  21  *          Artem Bityutskiy (Битюцкий Артём)
  22  *          Zoltan Sogor
  23  */
  24
  25 /*
  26  * This file provides a single place to access to compression and
  27  * decompression.
  28  */
  29
  30 #include <linux/crypto.h>
  31 #include "ubifs.h"
  32
  33 /* Fake description object for the "none" compressor */
  34 static struct ubifs_compressor none_compr = {
  35         .compr_type = UBIFS_COMPR_NONE,
  36         .name = "none",
  37         .capi_name = "",
  38 };
  39
  40 #ifdef CONFIG_UBIFS_FS_LZO
  41 static DEFINE_MUTEX(lzo_mutex);
  42
  43 static struct ubifs_compressor lzo_compr = {
  44         .compr_type = UBIFS_COMPR_LZO,
  45         .comp_mutex = &lzo_mutex,
  46         .name = "lzo",
  47         .capi_name = "lzo",
  48 };
  49 #else
  50 static struct ubifs_compressor lzo_compr = {
  51         .compr_type = UBIFS_COMPR_LZO,
  52         .name = "lzo",
  53 };
  54 #endif
  55
  56 #ifdef CONFIG_UBIFS_FS_ZLIB
  57 static DEFINE_MUTEX(deflate_mutex);
  58 static DEFINE_MUTEX(inflate_mutex);
  59
  60 static struct ubifs_compressor zlib_compr = {
  61         .compr_type = UBIFS_COMPR_ZLIB,
  62         .comp_mutex = &deflate_mutex,
  63         .decomp_mutex = &inflate_mutex,
  64         .name = "zlib",
  65         .capi_name = "deflate",
  66 };
  67 #else
  68 static struct ubifs_compressor zlib_compr = {
  69         .compr_type = UBIFS_COMPR_ZLIB,
  70         .name = "zlib",
  71 };
  72 #endif
  73
  74 /* All UBIFS compressors */
  75 struct ubifs_compressor *ubifs_compressors[UBIFS_COMPR_TYPES_CNT];
  76
  77 /**
  78  * ubifs_compress - compress data.
  79  * @in_buf: data to compress
  80  * @in_len: length of the data to compress
  81  * @out_buf: output buffer where compressed data should be stored
  82  * @out_len: output buffer length is returned here
  83  * @compr_type: type of compression to use on enter, actually used compression
  84  *              type on exit
  85  *
  86  * This function compresses input buffer @in_buf of length @in_len and stores
  87  * the result in the output buffer @out_buf and the resulting length in
  88  * @out_len. If the input buffer does not compress, it is just copied to the
  89  * @out_buf. The same happens if @compr_type is %UBIFS_COMPR_NONE or if
  90  * compression error occurred.
  91  *
  92  * Note, if the input buffer was not compressed, it is copied to the output
  93  * buffer and %UBIFS_COMPR_NONE is returned in @compr_type.
  94  */
  95 void ubifs_compress(const struct ubifs_info *c, const void *in_buf,
  96                     int in_len, void *out_buf, int *out_len, int *compr_type)
  97 {
  98         int err;
  99         struct ubifs_compressor *compr = ubifs_compressors[*compr_type];
 100
 101         if (*compr_type == UBIFS_COMPR_NONE)
 102                 goto no_compr;
 103
 104         /* If the input data is small, do not even try to compress it */
 105         if (in_len < UBIFS_MIN_COMPR_LEN)
 106                 goto no_compr;
 107
 108         if (compr->comp_mutex)
 109                 mutex_lock(compr->comp_mutex);
 110         err = crypto_comp_compress(compr->cc, in_buf, in_len, out_buf,
 111                                    (unsigned int *)out_len);
 112         if (compr->comp_mutex)
 113                 mutex_unlock(compr->comp_mutex);
 114         if (unlikely(err)) {
 115                 ubifs_warn(c, "cannot compress %d bytes, compressor %s, error %d, leave data uncompressed",
 116                            in_len, compr->name, err);
 117                 goto no_compr;
 118         }
 119
 120         /*
 121          * If the data compressed only slightly, it is better to leave it
 122          * uncompressed to improve read speed.
 123          */
 124         if (in_len - *out_len < UBIFS_MIN_COMPRESS_DIFF)
 125                 goto no_compr;
 126
 127         return;
 128
 129 no_compr:
 130         memcpy(out_buf, in_buf, in_len);
 131         *out_len = in_len;
 132         *compr_type = UBIFS_COMPR_NONE;
 133 }
 134
 135 /**
 136  * ubifs_decompress - decompress data.
 137  * @in_buf: data to decompress
 138  * @in_len: length of the data to decompress
 139  * @out_buf: output buffer where decompressed data should
 140  * @out_len: output length is returned here
 141  * @compr_type: type of compression
 142  *
 143  * This function decompresses data from buffer @in_buf into buffer @out_buf.
 144  * The length of the uncompressed data is returned in @out_len. This functions
 145  * returns %0 on success or a negative error code on failure.
 146  */
 147 int ubifs_decompress(const struct ubifs_info *c, const void *in_buf,
 148                      int in_len, void *out_buf, int *out_len, int compr_type)
 149 {
 150         int err;
 151         struct ubifs_compressor *compr;
 152
 153         if (unlikely(compr_type < 0 || compr_type >= UBIFS_COMPR_TYPES_CNT)) {
 154                 ubifs_err(c, "invalid compression type %d", compr_type);
 155                 return -EINVAL;
 156         }
 157
 158         compr = ubifs_compressors[compr_type];
 159
 160         if (unlikely(!compr->capi_name)) {
 161                 ubifs_err(c, "%s compression is not compiled in", compr->name);
 162                 return -EINVAL;
 163         }
 164
 165         if (compr_type == UBIFS_COMPR_NONE) {
 166                 memcpy(out_buf, in_buf, in_len);
 167                 *out_len = in_len;
 168                 return 0;
 169         }
 170
 171         if (compr->decomp_mutex)
 172                 mutex_lock(compr->decomp_mutex);
 173         err = crypto_comp_decompress(compr->cc, in_buf, in_len, out_buf,
 174                                      (unsigned int *)out_len);
 175         if (compr->decomp_mutex)
 176                 mutex_unlock(compr->decomp_mutex);
 177         if (err)
 178                 ubifs_err(c, "cannot decompress %d bytes, compressor %s, error %d",
 179                           in_len, compr->name, err);
 180
 181         return err;
 182 }
 183
 184 /**
 185  * compr_init - initialize a compressor.
 186  * @compr: compressor description object
 187  *
 188  * This function initializes the requested compressor and returns zero in case
 189  * of success or a negative error code in case of failure.
 190  */
 191 static int __init compr_init(struct ubifs_compressor *compr)
 192 {
 193         if (compr->capi_name) {
 194                 compr->cc = crypto_alloc_comp(compr->capi_name, 0, 0);
 195                 if (IS_ERR(compr->cc)) {
 196                         pr_err("UBIFS error (pid %d): cannot initialize compressor %s, error %ld",
 197                                current->pid, compr->name, PTR_ERR(compr->cc));
 198                         return PTR_ERR(compr->cc);
 199                 }
 200         }
 201
 202         ubifs_compressors[compr->compr_type] = compr;
 203         return 0;
 204 }
 205
 206 /**
 207  * compr_exit - de-initialize a compressor.
 208  * @compr: compressor description object
 209  */
 210 static void compr_exit(struct ubifs_compressor *compr)
 211 {
 212         if (compr->capi_name)
 213                 crypto_free_comp(compr->cc);
 214         return;
 215 }
 216
 217 /**
 218  * ubifs_compressors_init - initialize UBIFS compressors.
 219  *
 220  * This function initializes the compressor which were compiled in. Returns
 221  * zero in case of success and a negative error code in case of failure.
 222  */
 223 int __init ubifs_compressors_init(void)
 224 {
 225         int err;
 226
 227         err = compr_init(&lzo_compr);
 228         if (err)
 229                 return err;
 230
 231         err = compr_init(&zlib_compr);
 232         if (err)
 233                 goto out_lzo;
 234
 235         ubifs_compressors[UBIFS_COMPR_NONE] = &none_compr;
 236         return 0;
 237
 238 out_lzo:
 239         compr_exit(&lzo_compr);
 240         return err;
 241 }
 242
 243 /**
 244  * ubifs_compressors_exit - de-initialize UBIFS compressors.
 245  */
 246 void ubifs_compressors_exit(void)
 247 {
 248         compr_exit(&lzo_compr);
 249         compr_exit(&zlib_compr);
 250 }