compr.c

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/*
 * fs/logfs/compr.c - compression routines
 *
 * As should be obvious for Linux kernel code, license is GPLv2
 *
 * Copyright (c) 2005-2008 Joern Engel <[email protected]>
 */
#include "logfs.h"
#include <linux/vmalloc.h>
#include <linux/zlib.h>

#define COMPR_LEVEL 3

static DEFINE_MUTEX(compr_mutex);
static struct z_stream_s stream;

int logfs_compress(void *in, void *out, size_t inlen, size_t outlen)
{
    int err, ret;

    ret = -EIO;
    mutex_lock(&compr_mutex);
    err = zlib_deflateInit(&stream, COMPR_LEVEL);
    if (err != Z_OK)
        goto error;

    stream.next_in = in;
    stream.avail_in = inlen;
    stream.total_in = 0;
    stream.next_out = out;
    stream.avail_out = outlen;
    stream.total_out = 0;

    err = zlib_deflate(&stream, Z_FINISH);
    if (err != Z_STREAM_END)
        goto error;

    err = zlib_deflateEnd(&stream);
    if (err != Z_OK)
        goto error;

    if (stream.total_out >= stream.total_in)
        goto error;

    ret = stream.total_out;
error:
    mutex_unlock(&compr_mutex);
    return ret;
}

int logfs_uncompress(void *in, void *out, size_t inlen, size_t outlen)
{
    int err, ret;

    ret = -EIO;
    mutex_lock(&compr_mutex);
    err = zlib_inflateInit(&stream);
    if (err != Z_OK)
        goto error;

    stream.next_in = in;
    stream.avail_in = inlen;
    stream.total_in = 0;
    stream.next_out = out;
    stream.avail_out = outlen;
    stream.total_out = 0;

    err = zlib_inflate(&stream, Z_FINISH);
    if (err != Z_STREAM_END)
        goto error;

    err = zlib_inflateEnd(&stream);
    if (err != Z_OK)
        goto error;

    ret = 0;
error:
    mutex_unlock(&compr_mutex);
    return ret;
}

int __init logfs_compr_init(void)
{
    size_t size = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
            zlib_inflate_workspacesize());
    stream.workspace = vmalloc(size);
    if (!stream.workspace)
        return -ENOMEM;
    return 0;
}

void logfs_compr_exit(void)
{
    vfree(stream.workspace);
}