text: /*
   * fs/logfs/compr.c	- compression routines
   *
   * As should be obvious for Linux kernel code, license is GPLv2
   *
   * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
   */
  #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(),
  			zlib_inflate_workspacesize());
  	stream.workspace = vmalloc(size);
  	if (!stream.workspace)
  		return -ENOMEM;
  	return 0;
  }
  
  void logfs_compr_exit(void)
  {
  	vfree(stream.workspace);
  }
  