linux/fs/ubifs/compress.c
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   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 */
  34static 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
  41static DEFINE_MUTEX(lzo_mutex);
  42
  43static 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
  50static struct ubifs_compressor lzo_compr = {
  51        .compr_type = UBIFS_COMPR_LZO,
  52        .name = "lzo",
  53};
  54#endif
  55
  56#ifdef CONFIG_UBIFS_FS_ZLIB
  57static DEFINE_MUTEX(deflate_mutex);
  58static DEFINE_MUTEX(inflate_mutex);
  59
  60static 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
  68static struct ubifs_compressor zlib_compr = {
  69        .compr_type = UBIFS_COMPR_ZLIB,
  70        .name = "zlib",
  71};
  72#endif
  73
  74/* All UBIFS compressors */
  75struct 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 */
  95void ubifs_compress(const void *in_buf, int in_len, void *out_buf, int *out_len,
  96                    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("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
 129no_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 */
 147int ubifs_decompress(const void *in_buf, int in_len, void *out_buf,
 148                     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("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("%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("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 */
 191static 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                        ubifs_err("cannot initialize compressor %s, error %ld",
 197                                  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 */
 210static 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 */
 223int __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
 238out_lzo:
 239        compr_exit(&lzo_compr);
 240        return err;
 241}
 242
 243/**
 244 * ubifs_compressors_exit - de-initialize UBIFS compressors.
 245 */
 246void ubifs_compressors_exit(void)
 247{
 248        compr_exit(&lzo_compr);
 249        compr_exit(&zlib_compr);
 250}
 251
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