kernel/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  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  28  * Copyright (c) 2013, 2018 by Delphix. All rights reserved.
  29  */
  30
  31 #include <sys/zfs_context.h>
  32 #include <sys/compress.h>
  33 #include <sys/spa.h>
  34 #include <sys/zfeature.h>
  35 #include <sys/zio.h>
  36 #include <sys/zio_compress.h>
  37
  38 /*
  39  * If nonzero, every 1/X decompression attempts will fail, simulating
  40  * an undetected memory error.
  41  */
  42 uint64_t zio_decompress_fail_fraction = 0;
  43
  44 /*
  45  * Compression vectors.
  46  */
  47 zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
  48         {"inherit",             0,      NULL,           NULL},
  49         {"on",                  0,      NULL,           NULL},
  50         {"uncompressed",        0,      NULL,           NULL},
  51         {"lzjb",                0,      lzjb_compress,  lzjb_decompress},
  52         {"empty",               0,      NULL,           NULL},
  53         {"gzip-1",              1,      gzip_compress,  gzip_decompress},
  54         {"gzip-2",              2,      gzip_compress,  gzip_decompress},
  55         {"gzip-3",              3,      gzip_compress,  gzip_decompress},
  56         {"gzip-4",              4,      gzip_compress,  gzip_decompress},
  57         {"gzip-5",              5,      gzip_compress,  gzip_decompress},
  58         {"gzip-6",              6,      gzip_compress,  gzip_decompress},
  59         {"gzip-7",              7,      gzip_compress,  gzip_decompress},
  60         {"gzip-8",              8,      gzip_compress,  gzip_decompress},
  61         {"gzip-9",              9,      gzip_compress,  gzip_decompress},
  62         {"zle",                 64,     zle_compress,   zle_decompress},
  63         {"lz4",                 0,      lz4_compress,   lz4_decompress}
  64 };
  65
  66 enum zio_compress
  67 zio_compress_select(spa_t *spa, enum zio_compress child,
  68     enum zio_compress parent)
  69 {
  70         enum zio_compress result;
  71
  72         ASSERT(child < ZIO_COMPRESS_FUNCTIONS);
  73         ASSERT(parent < ZIO_COMPRESS_FUNCTIONS);
  74         ASSERT(parent != ZIO_COMPRESS_INHERIT);
  75
  76         result = child;
  77         if (result == ZIO_COMPRESS_INHERIT)
  78                 result = parent;
  79
  80         if (result == ZIO_COMPRESS_ON) {
  81                 if (spa_feature_is_active(spa, SPA_FEATURE_LZ4_COMPRESS))
  82                         result = ZIO_COMPRESS_LZ4_ON_VALUE;
  83                 else
  84                         result = ZIO_COMPRESS_LEGACY_ON_VALUE;
  85         }
  86
  87         return (result);
  88 }
  89
  90 /*ARGSUSED*/
  91 static int
  92 zio_compress_zeroed_cb(void *data, size_t len, void *private)
  93 {
  94         uint64_t *end = (uint64_t *)((char *)data + len);
  95         for (uint64_t *word = (uint64_t *)data; word < end; word++)
  96                 if (*word != 0)
  97                         return (1);
  98
  99         return (0);
 100 }
 101
 102 size_t
 103 zio_compress_data(enum zio_compress c, abd_t *src, void *dst, size_t s_len)
 104 {
 105         size_t c_len, d_len;
 106         zio_compress_info_t *ci = &zio_compress_table[c];
 107
 108         ASSERT((uint_t)c < ZIO_COMPRESS_FUNCTIONS);
 109         ASSERT((uint_t)c == ZIO_COMPRESS_EMPTY || ci->ci_compress != NULL);
 110
 111         /*
 112          * If the data is all zeroes, we don't even need to allocate
 113          * a block for it.  We indicate this by returning zero size.
 114          */
 115         if (abd_iterate_func(src, 0, s_len, zio_compress_zeroed_cb, NULL) == 0)
 116                 return (0);
 117
 118         if (c == ZIO_COMPRESS_EMPTY)
 119                 return (s_len);
 120
 121         /* Compress at least 12.5% */
 122         d_len = s_len - (s_len >> 3);
 123
 124         /* No compression algorithms can read from ABDs directly */
 125         void *tmp = abd_borrow_buf_copy(src, s_len);
 126         c_len = ci->ci_compress(tmp, dst, s_len, d_len, ci->ci_level);
 127         abd_return_buf(src, tmp, s_len);
 128
 129         if (c_len > d_len)
 130                 return (s_len);
 131
 132         ASSERT3U(c_len, <=, d_len);
 133         return (c_len);
 134 }
 135
 136 int
 137 zio_decompress_data_buf(enum zio_compress c, void *src, void *dst,
 138     size_t s_len, size_t d_len)
 139 {
 140         zio_compress_info_t *ci = &zio_compress_table[c];
 141         if ((uint_t)c >= ZIO_COMPRESS_FUNCTIONS || ci->ci_decompress == NULL)
 142                 return (SET_ERROR(EINVAL));
 143
 144         return (ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level));
 145 }
 146
 147 int
 148 zio_decompress_data(enum zio_compress c, abd_t *src, void *dst,
 149     size_t s_len, size_t d_len)
 150 {
 151         void *tmp = abd_borrow_buf_copy(src, s_len);
 152         int ret = zio_decompress_data_buf(c, tmp, dst, s_len, d_len);
 153         abd_return_buf(src, tmp, s_len);
 154
 155         /*
 156          * Decompression shouldn't fail, because we've already verifyied
 157          * the checksum.  However, for extra protection (e.g. against bitflips
 158          * in non-ECC RAM), we handle this error (and test it).
 159          */
 160         ASSERT0(ret);
 161         if (zio_decompress_fail_fraction != 0 &&
 162             spa_get_random(zio_decompress_fail_fraction) == 0)
 163                 ret = SET_ERROR(EINVAL);
 164
 165         return (ret);
 166 }