compress.c

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/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 * Copyright (C) 2006, 2007 University of Szeged, Hungary
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Adrian Hunter
 *          Artem Bityutskiy (Битюцкий Артём)
 *          Zoltan Sogor
 */

/*
 * This file provides a single place to access to compression and
 * decompression.
 */

#include <linux/crypto.h>
#include "ubifs.h"

/* Fake description object for the "none" compressor */
static struct ubifs_compressor none_compr = {
    .compr_type = UBIFS_COMPR_NONE,
    .name = "none",
    .capi_name = "",
};

#ifdef CONFIG_UBIFS_FS_LZO
static DEFINE_MUTEX(lzo_mutex);

static struct ubifs_compressor lzo_compr = {
    .compr_type = UBIFS_COMPR_LZO,
    .comp_mutex = &lzo_mutex,
    .name = "lzo",
    .capi_name = "lzo",
};
#else
static struct ubifs_compressor lzo_compr = {
    .compr_type = UBIFS_COMPR_LZO,
    .name = "lzo",
};
#endif

#ifdef CONFIG_UBIFS_FS_ZLIB
static DEFINE_MUTEX(deflate_mutex);
static DEFINE_MUTEX(inflate_mutex);

static struct ubifs_compressor zlib_compr = {
    .compr_type = UBIFS_COMPR_ZLIB,
    .comp_mutex = &deflate_mutex,
    .decomp_mutex = &inflate_mutex,
    .name = "zlib",
    .capi_name = "deflate",
};
#else
static struct ubifs_compressor zlib_compr = {
    .compr_type = UBIFS_COMPR_ZLIB,
    .name = "zlib",
};
#endif

/* All UBIFS compressors */
struct ubifs_compressor *ubifs_compressors[UBIFS_COMPR_TYPES_CNT];

void ubifs_compress(const void *in_buf, int in_len, void *out_buf, int *out_len,
            int *compr_type)
{
    int err;
    struct ubifs_compressor *compr = ubifs_compressors[*compr_type];

    if (*compr_type == UBIFS_COMPR_NONE)
        goto no_compr;

    /* If the input data is small, do not even try to compress it */
    if (in_len < UBIFS_MIN_COMPR_LEN)
        goto no_compr;

    if (compr->comp_mutex)
        mutex_lock(compr->comp_mutex);
    err = crypto_comp_compress(compr->cc, in_buf, in_len, out_buf,
                   (unsigned int *)out_len);
    if (compr->comp_mutex)
        mutex_unlock(compr->comp_mutex);
    if (unlikely(err)) {
        ubifs_warn("cannot compress %d bytes, compressor %s, error %d, leave data uncompressed",
               in_len, compr->name, err);
         goto no_compr;
    }

    /*
     * If the data compressed only slightly, it is better to leave it
     * uncompressed to improve read speed.
     */
    if (in_len - *out_len < UBIFS_MIN_COMPRESS_DIFF)
        goto no_compr;

    return;

no_compr:
    memcpy(out_buf, in_buf, in_len);
    *out_len = in_len;
    *compr_type = UBIFS_COMPR_NONE;
}

int ubifs_decompress(const void *in_buf, int in_len, void *out_buf,
             int *out_len, int compr_type)
{
    int err;
    struct ubifs_compressor *compr;

    if (unlikely(compr_type < 0 || compr_type >= UBIFS_COMPR_TYPES_CNT)) {
        ubifs_err("invalid compression type %d", compr_type);
        return -EINVAL;
    }

    compr = ubifs_compressors[compr_type];

    if (unlikely(!compr->capi_name)) {
        ubifs_err("%s compression is not compiled in", compr->name);
        return -EINVAL;
    }

    if (compr_type == UBIFS_COMPR_NONE) {
        memcpy(out_buf, in_buf, in_len);
        *out_len = in_len;
        return 0;
    }

    if (compr->decomp_mutex)
        mutex_lock(compr->decomp_mutex);
    err = crypto_comp_decompress(compr->cc, in_buf, in_len, out_buf,
                     (unsigned int *)out_len);
    if (compr->decomp_mutex)
        mutex_unlock(compr->decomp_mutex);
    if (err)
        ubifs_err("cannot decompress %d bytes, compressor %s, error %d",
              in_len, compr->name, err);

    return err;
}

static int __init compr_init(struct ubifs_compressor *compr)
{
    if (compr->capi_name) {
        compr->cc = crypto_alloc_comp(compr->capi_name, 0, 0);
        if (IS_ERR(compr->cc)) {
            ubifs_err("cannot initialize compressor %s, error %ld",
                  compr->name, PTR_ERR(compr->cc));
            return PTR_ERR(compr->cc);
        }
    }

    ubifs_compressors[compr->compr_type] = compr;
    return 0;
}

static void compr_exit(struct ubifs_compressor *compr)
{
    if (compr->capi_name)
        crypto_free_comp(compr->cc);
    return;
}

int __init ubifs_compressors_init(void)
{
    int err;

    err = compr_init(&lzo_compr);
    if (err)
        return err;

    err = compr_init(&zlib_compr);
    if (err)
        goto out_lzo;

    ubifs_compressors[UBIFS_COMPR_NONE] = &none_compr;
    return 0;

out_lzo:
    compr_exit(&lzo_compr);
    return err;
}

void ubifs_compressors_exit(void)
{
    compr_exit(&lzo_compr);
    compr_exit(&zlib_compr);
}