usr/src/uts/common/fs/zfs/zio_compress.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #include <sys/zfs_context.h>
  28 #include <sys/compress.h>
  29 #include <sys/spa.h>
  30 #include <sys/zio.h>
  31 #include <sys/zio_compress.h>
  32
  33 /*
  34  * Compression vectors.
  35  */
  36
  37 zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
  38         {NULL,                  NULL,                   0,      "inherit"},
  39         {NULL,                  NULL,                   0,      "on"},
  40         {NULL,                  NULL,                   0,      "uncompressed"},
  41         {lzjb_compress,         lzjb_decompress,        0,      "lzjb"},
  42         {NULL,                  NULL,                   0,      "empty"},
  43         {gzip_compress,         gzip_decompress,        1,      "gzip-1"},
  44         {gzip_compress,         gzip_decompress,        2,      "gzip-2"},
  45         {gzip_compress,         gzip_decompress,        3,      "gzip-3"},
  46         {gzip_compress,         gzip_decompress,        4,      "gzip-4"},
  47         {gzip_compress,         gzip_decompress,        5,      "gzip-5"},
  48         {gzip_compress,         gzip_decompress,        6,      "gzip-6"},
  49         {gzip_compress,         gzip_decompress,        7,      "gzip-7"},
  50         {gzip_compress,         gzip_decompress,        8,      "gzip-8"},
  51         {gzip_compress,         gzip_decompress,        9,      "gzip-9"},
  52         {zle_compress,          zle_decompress,         64,     "zle"},
  53 };
  54
  55 enum zio_compress
  56 zio_compress_select(enum zio_compress child, enum zio_compress parent)
  57 {
  58         ASSERT(child < ZIO_COMPRESS_FUNCTIONS);
  59         ASSERT(parent < ZIO_COMPRESS_FUNCTIONS);
  60         ASSERT(parent != ZIO_COMPRESS_INHERIT && parent != ZIO_COMPRESS_ON);
  61
  62         if (child == ZIO_COMPRESS_INHERIT)
  63                 return (parent);
  64
  65         if (child == ZIO_COMPRESS_ON)
  66                 return (ZIO_COMPRESS_ON_VALUE);
  67
  68         return (child);
  69 }
  70
  71 size_t
  72 zio_compress_data(enum zio_compress c, void *src, void *dst, size_t s_len)
  73 {
  74         uint64_t *word, *word_end;
  75         size_t c_len, d_len, r_len;
  76         zio_compress_info_t *ci = &zio_compress_table[c];
  77
  78         ASSERT((uint_t)c < ZIO_COMPRESS_FUNCTIONS);
  79         ASSERT((uint_t)c == ZIO_COMPRESS_EMPTY || ci->ci_compress != NULL);
  80
  81         /*
  82          * If the data is all zeroes, we don't even need to allocate
  83          * a block for it.  We indicate this by returning zero size.
  84          */
  85         word_end = (uint64_t *)((char *)src + s_len);
  86         for (word = src; word < word_end; word++)
  87                 if (*word != 0)
  88                         break;
  89
  90         if (word == word_end)
  91                 return (0);
  92
  93         if (c == ZIO_COMPRESS_EMPTY)
  94                 return (s_len);
  95
  96         /* Compress at least 12.5% */
  97         d_len = P2ALIGN(s_len - (s_len >> 3), (size_t)SPA_MINBLOCKSIZE);
  98         if (d_len == 0)
  99                 return (s_len);
 100
 101         c_len = ci->ci_compress(src, dst, s_len, d_len, ci->ci_level);
 102
 103         if (c_len > d_len)
 104                 return (s_len);
 105
 106         /*
 107          * Cool.  We compressed at least as much as we were hoping to.
 108          * For both security and repeatability, pad out the last sector.
 109          */
 110         r_len = P2ROUNDUP(c_len, (size_t)SPA_MINBLOCKSIZE);
 111         if (r_len > c_len) {
 112                 bzero((char *)dst + c_len, r_len - c_len);
 113                 c_len = r_len;
 114         }
 115
 116         ASSERT3U(c_len, <=, d_len);
 117         ASSERT(P2PHASE(c_len, (size_t)SPA_MINBLOCKSIZE) == 0);
 118
 119         return (c_len);
 120 }
 121
 122 int
 123 zio_decompress_data(enum zio_compress c, void *src, void *dst,
 124     size_t s_len, size_t d_len)
 125 {
 126         zio_compress_info_t *ci = &zio_compress_table[c];
 127
 128         if ((uint_t)c >= ZIO_COMPRESS_FUNCTIONS || ci->ci_decompress == NULL)
 129                 return (EINVAL);
 130
 131         return (ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level));
 132 }