module/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  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  28  */
  29
  30 /*
  31  * Copyright (c) 2013, 2018 by Delphix. All rights reserved.
  32  */
  33
  34 #include <sys/zfs_context.h>
  35 #include <sys/spa.h>
  36 #include <sys/zfeature.h>
  37 #include <sys/zio.h>
  38 #include <sys/zio_compress.h>
  39
  40 /*
  41  * If nonzero, every 1/X decompression attempts will fail, simulating
  42  * an undetected memory error.
  43  */
  44 unsigned long zio_decompress_fail_fraction = 0;
  45
  46 /*
  47  * Compression vectors.
  48  */
  49 zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
  50         {"inherit",             0,      NULL,           NULL},
  51         {"on",                  0,      NULL,           NULL},
  52         {"uncompressed",        0,      NULL,           NULL},
  53         {"lzjb",                0,      lzjb_compress,  lzjb_decompress},
  54         {"empty",               0,      NULL,           NULL},
  55         {"gzip-1",              1,      gzip_compress,  gzip_decompress},
  56         {"gzip-2",              2,      gzip_compress,  gzip_decompress},
  57         {"gzip-3",              3,      gzip_compress,  gzip_decompress},
  58         {"gzip-4",              4,      gzip_compress,  gzip_decompress},
  59         {"gzip-5",              5,      gzip_compress,  gzip_decompress},
  60         {"gzip-6",              6,      gzip_compress,  gzip_decompress},
  61         {"gzip-7",              7,      gzip_compress,  gzip_decompress},
  62         {"gzip-8",              8,      gzip_compress,  gzip_decompress},
  63         {"gzip-9",              9,      gzip_compress,  gzip_decompress},
  64         {"zle",                 64,     zle_compress,   zle_decompress},
  65         {"lz4",                 0,      lz4_compress_zfs, lz4_decompress_zfs}
  66 };
  67
  68 enum zio_compress
  69 zio_compress_select(spa_t *spa, enum zio_compress child,
  70     enum zio_compress parent)
  71 {
  72         enum zio_compress result;
  73
  74         ASSERT(child < ZIO_COMPRESS_FUNCTIONS);
  75         ASSERT(parent < ZIO_COMPRESS_FUNCTIONS);
  76         ASSERT(parent != ZIO_COMPRESS_INHERIT);
  77
  78         result = child;
  79         if (result == ZIO_COMPRESS_INHERIT)
  80                 result = parent;
  81
  82         if (result == ZIO_COMPRESS_ON) {
  83                 if (spa_feature_is_active(spa, SPA_FEATURE_LZ4_COMPRESS))
  84                         result = ZIO_COMPRESS_LZ4_ON_VALUE;
  85                 else
  86                         result = ZIO_COMPRESS_LEGACY_ON_VALUE;
  87         }
  88
  89         return (result);
  90 }
  91
  92 /*ARGSUSED*/
  93 static int
  94 zio_compress_zeroed_cb(void *data, size_t len, void *private)
  95 {
  96         uint64_t *end = (uint64_t *)((char *)data + len);
  97         for (uint64_t *word = (uint64_t *)data; word < end; word++)
  98                 if (*word != 0)
  99                         return (1);
 100
 101         return (0);
 102 }
 103
 104 size_t
 105 zio_compress_data(enum zio_compress c, abd_t *src, void *dst, size_t s_len)
 106 {
 107         size_t c_len, d_len;
 108         zio_compress_info_t *ci = &zio_compress_table[c];
 109
 110         ASSERT((uint_t)c < ZIO_COMPRESS_FUNCTIONS);
 111         ASSERT((uint_t)c == ZIO_COMPRESS_EMPTY || ci->ci_compress != NULL);
 112
 113         /*
 114          * If the data is all zeroes, we don't even need to allocate
 115          * a block for it.  We indicate this by returning zero size.
 116          */
 117         if (abd_iterate_func(src, 0, s_len, zio_compress_zeroed_cb, NULL) == 0)
 118                 return (0);
 119
 120         if (c == ZIO_COMPRESS_EMPTY)
 121                 return (s_len);
 122
 123         /* Compress at least 12.5% */
 124         d_len = s_len - (s_len >> 3);
 125
 126         /* No compression algorithms can read from ABDs directly */
 127         void *tmp = abd_borrow_buf_copy(src, s_len);
 128         c_len = ci->ci_compress(tmp, dst, s_len, d_len, ci->ci_level);
 129         abd_return_buf(src, tmp, s_len);
 130
 131         if (c_len > d_len)
 132                 return (s_len);
 133
 134         ASSERT3U(c_len, <=, d_len);
 135         return (c_len);
 136 }
 137
 138 int
 139 zio_decompress_data_buf(enum zio_compress c, void *src, void *dst,
 140     size_t s_len, size_t d_len)
 141 {
 142         zio_compress_info_t *ci = &zio_compress_table[c];
 143         if ((uint_t)c >= ZIO_COMPRESS_FUNCTIONS || ci->ci_decompress == NULL)
 144                 return (SET_ERROR(EINVAL));
 145
 146         return (ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level));
 147 }
 148
 149 int
 150 zio_decompress_data(enum zio_compress c, abd_t *src, void *dst,
 151     size_t s_len, size_t d_len)
 152 {
 153         void *tmp = abd_borrow_buf_copy(src, s_len);
 154         int ret = zio_decompress_data_buf(c, tmp, dst, s_len, d_len);
 155         abd_return_buf(src, tmp, s_len);
 156
 157         /*
 158          * Decompression shouldn't fail, because we've already verifyied
 159          * the checksum.  However, for extra protection (e.g. against bitflips
 160          * in non-ECC RAM), we handle this error (and test it).
 161          */
 162         ASSERT0(ret);
 163         if (zio_decompress_fail_fraction != 0 &&
 164             spa_get_random(zio_decompress_fail_fraction) == 0)
 165                 ret = SET_ERROR(EINVAL);
 166
 167         return (ret);
 168 }