zfs/lib/libzpool/zio_checksum.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  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 #pragma ident   "@(#)zio_checksum.c     1.6     06/11/10 SMI"
  27
  28 #include <sys/zfs_context.h>
  29 #include <sys/spa.h>
  30 #include <sys/zio.h>
  31 #include <sys/zio_checksum.h>
  32
  33 /*
  34  * Checksum vectors.
  35  *
  36  * In the SPA, everything is checksummed.  We support checksum vectors
  37  * for three distinct reasons:
  38  *
  39  *   1. Different kinds of data need different levels of protection.
  40  *      For SPA metadata, we always want a very strong checksum.
  41  *      For user data, we let users make the trade-off between speed
  42  *      and checksum strength.
  43  *
  44  *   2. Cryptographic hash and MAC algorithms are an area of active research.
  45  *      It is likely that in future hash functions will be at least as strong
  46  *      as current best-of-breed, and may be substantially faster as well.
  47  *      We want the ability to take advantage of these new hashes as soon as
  48  *      they become available.
  49  *
  50  *   3. If someone develops hardware that can compute a strong hash quickly,
  51  *      we want the ability to take advantage of that hardware.
  52  *
  53  * Of course, we don't want a checksum upgrade to invalidate existing
  54  * data, so we store the checksum *function* in five bits of the DVA.
  55  * This gives us room for up to 32 different checksum functions.
  56  *
  57  * When writing a block, we always checksum it with the latest-and-greatest
  58  * checksum function of the appropriate strength.  When reading a block,
  59  * we compare the expected checksum against the actual checksum, which we
  60  * compute via the checksum function specified in the DVA encoding.
  61  */
  62
  63 /*ARGSUSED*/
  64 static void
  65 zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)
  66 {
  67         ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
  68 }
  69
  70 zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
  71         {{NULL,                 NULL},                  0, 0,   "inherit"},
  72         {{NULL,                 NULL},                  0, 0,   "on"},
  73         {{zio_checksum_off,     zio_checksum_off},      0, 0,   "off"},
  74         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 1,   "label"},
  75         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 1,   "gang_header"},
  76         {{fletcher_2_native,    fletcher_2_byteswap},   0, 1,   "zilog"},
  77         {{fletcher_2_native,    fletcher_2_byteswap},   0, 0,   "fletcher2"},
  78         {{fletcher_4_native,    fletcher_4_byteswap},   1, 0,   "fletcher4"},
  79         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 0,   "SHA256"},
  80 };
  81
  82 uint8_t
  83 zio_checksum_select(uint8_t child, uint8_t parent)
  84 {
  85         ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);
  86         ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);
  87         ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
  88
  89         if (child == ZIO_CHECKSUM_INHERIT)
  90                 return (parent);
  91
  92         if (child == ZIO_CHECKSUM_ON)
  93                 return (ZIO_CHECKSUM_ON_VALUE);
  94
  95         return (child);
  96 }
  97
  98 /*
  99  * Generate the checksum.
 100  */
 101 void
 102 zio_checksum(uint_t checksum, zio_cksum_t *zcp, void *data, uint64_t size)
 103 {
 104         zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;
 105         zio_checksum_info_t *ci = &zio_checksum_table[checksum];
 106         zio_cksum_t zbt_cksum;
 107
 108         ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);
 109         ASSERT(ci->ci_func[0] != NULL);
 110
 111         if (ci->ci_zbt) {
 112                 *zcp = zbt->zbt_cksum;
 113                 zbt->zbt_magic = ZBT_MAGIC;
 114                 ci->ci_func[0](data, size, &zbt_cksum);
 115                 zbt->zbt_cksum = zbt_cksum;
 116         } else {
 117                 ci->ci_func[0](data, size, zcp);
 118         }
 119 }
 120
 121 int
 122 zio_checksum_error(zio_t *zio)
 123 {
 124         blkptr_t *bp = zio->io_bp;
 125         zio_cksum_t zc = bp->blk_cksum;
 126         uint_t checksum = BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER :
 127             BP_GET_CHECKSUM(bp);
 128         int byteswap = BP_SHOULD_BYTESWAP(bp);
 129         void *data = zio->io_data;
 130         uint64_t size = ZIO_GET_IOSIZE(zio);
 131         zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;
 132         zio_checksum_info_t *ci = &zio_checksum_table[checksum];
 133         zio_cksum_t actual_cksum, expected_cksum;
 134
 135         if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
 136                 return (EINVAL);
 137
 138         if (ci->ci_zbt) {
 139                 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
 140                         zio_set_gang_verifier(zio, &zc);
 141
 142                 if (zbt->zbt_magic == BSWAP_64(ZBT_MAGIC)) {
 143                         expected_cksum = zbt->zbt_cksum;
 144                         byteswap_uint64_array(&expected_cksum,
 145                             sizeof (zio_cksum_t));
 146                         zbt->zbt_cksum = zc;
 147                         byteswap_uint64_array(&zbt->zbt_cksum,
 148                             sizeof (zio_cksum_t));
 149                         ci->ci_func[1](data, size, &actual_cksum);
 150                         zbt->zbt_cksum = expected_cksum;
 151                         byteswap_uint64_array(&zbt->zbt_cksum,
 152                             sizeof (zio_cksum_t));
 153                 } else {
 154                         expected_cksum = zbt->zbt_cksum;
 155                         zbt->zbt_cksum = zc;
 156                         ci->ci_func[0](data, size, &actual_cksum);
 157                         zbt->zbt_cksum = expected_cksum;
 158                 }
 159                 zc = expected_cksum;
 160         } else {
 161                 ASSERT(!BP_IS_GANG(bp));
 162                 ci->ci_func[byteswap](data, size, &actual_cksum);
 163         }
 164
 165         if (!ZIO_CHECKSUM_EQUAL(actual_cksum, zc))
 166                 return (ECKSUM);
 167
 168         if (zio_injection_enabled && !zio->io_error)
 169                 return (zio_handle_fault_injection(zio, ECKSUM));
 170
 171         return (0);
 172 }