fs/logfs/compr.c

   1 /*
   2  * fs/logfs/compr.c     - compression routines
   3  *
   4  * As should be obvious for Linux kernel code, license is GPLv2
   5  *
   6  * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
   7  */
   8 #include "logfs.h"
   9 #include <linux/vmalloc.h>
  10 #include <linux/zlib.h>
  11
  12 #define COMPR_LEVEL 3
  13
  14 static DEFINE_MUTEX(compr_mutex);
  15 static struct z_stream_s stream;
  16
  17 int logfs_compress(void *in, void *out, size_t inlen, size_t outlen)
  18 {
  19         int err, ret;
  20
  21         ret = -EIO;
  22         mutex_lock(&compr_mutex);
  23         err = zlib_deflateInit(&stream, COMPR_LEVEL);
  24         if (err != Z_OK)
  25                 goto error;
  26
  27         stream.next_in = in;
  28         stream.avail_in = inlen;
  29         stream.total_in = 0;
  30         stream.next_out = out;
  31         stream.avail_out = outlen;
  32         stream.total_out = 0;
  33
  34         err = zlib_deflate(&stream, Z_FINISH);
  35         if (err != Z_STREAM_END)
  36                 goto error;
  37
  38         err = zlib_deflateEnd(&stream);
  39         if (err != Z_OK)
  40                 goto error;
  41
  42         if (stream.total_out >= stream.total_in)
  43                 goto error;
  44
  45         ret = stream.total_out;
  46 error:
  47         mutex_unlock(&compr_mutex);
  48         return ret;
  49 }
  50
  51 int logfs_uncompress(void *in, void *out, size_t inlen, size_t outlen)
  52 {
  53         int err, ret;
  54
  55         ret = -EIO;
  56         mutex_lock(&compr_mutex);
  57         err = zlib_inflateInit(&stream);
  58         if (err != Z_OK)
  59                 goto error;
  60
  61         stream.next_in = in;
  62         stream.avail_in = inlen;
  63         stream.total_in = 0;
  64         stream.next_out = out;
  65         stream.avail_out = outlen;
  66         stream.total_out = 0;
  67
  68         err = zlib_inflate(&stream, Z_FINISH);
  69         if (err != Z_STREAM_END)
  70                 goto error;
  71
  72         err = zlib_inflateEnd(&stream);
  73         if (err != Z_OK)
  74                 goto error;
  75
  76         ret = 0;
  77 error:
  78         mutex_unlock(&compr_mutex);
  79         return ret;
  80 }
  81
  82 int __init logfs_compr_init(void)
  83 {
  84         size_t size = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
  85                         zlib_inflate_workspacesize());
  86         stream.workspace = vmalloc(size);
  87         if (!stream.workspace)
  88                 return -ENOMEM;
  89         return 0;
  90 }
  91
  92 void logfs_compr_exit(void)
  93 {
  94         vfree(stream.workspace);
  95 }