usr/src/uts/common/fs/zfs/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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  */
  24
  25 #include <sys/zfs_context.h>
  26 #include <sys/spa.h>
  27 #include <sys/zio.h>
  28 #include <sys/zio_checksum.h>
  29 #include <sys/zil.h>
  30 #include <zfs_fletcher.h>
  31
  32 /*
  33  * Checksum vectors.
  34  *
  35  * In the SPA, everything is checksummed.  We support checksum vectors
  36  * for three distinct reasons:
  37  *
  38  *   1. Different kinds of data need different levels of protection.
  39  *      For SPA metadata, we always want a very strong checksum.
  40  *      For user data, we let users make the trade-off between speed
  41  *      and checksum strength.
  42  *
  43  *   2. Cryptographic hash and MAC algorithms are an area of active research.
  44  *      It is likely that in future hash functions will be at least as strong
  45  *      as current best-of-breed, and may be substantially faster as well.
  46  *      We want the ability to take advantage of these new hashes as soon as
  47  *      they become available.
  48  *
  49  *   3. If someone develops hardware that can compute a strong hash quickly,
  50  *      we want the ability to take advantage of that hardware.
  51  *
  52  * Of course, we don't want a checksum upgrade to invalidate existing
  53  * data, so we store the checksum *function* in eight bits of the bp.
  54  * This gives us room for up to 256 different checksum functions.
  55  *
  56  * When writing a block, we always checksum it with the latest-and-greatest
  57  * checksum function of the appropriate strength.  When reading a block,
  58  * we compare the expected checksum against the actual checksum, which we
  59  * compute via the checksum function specified by BP_GET_CHECKSUM(bp).
  60  */
  61
  62 /*ARGSUSED*/
  63 static void
  64 zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)
  65 {
  66         ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
  67 }
  68
  69 zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
  70         {{NULL,                 NULL},                  0, 0, 0, "inherit"},
  71         {{NULL,                 NULL},                  0, 0, 0, "on"},
  72         {{zio_checksum_off,     zio_checksum_off},      0, 0, 0, "off"},
  73         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 1, 0, "label"},
  74         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 1, 0, "gang_header"},
  75         {{fletcher_2_native,    fletcher_2_byteswap},   0, 1, 0, "zilog"},
  76         {{fletcher_2_native,    fletcher_2_byteswap},   0, 0, 0, "fletcher2"},
  77         {{fletcher_4_native,    fletcher_4_byteswap},   1, 0, 0, "fletcher4"},
  78         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 0, 1, "sha256"},
  79         {{fletcher_4_native,    fletcher_4_byteswap},   0, 1, 0, "zilog2"},
  80 };
  81
  82 enum zio_checksum
  83 zio_checksum_select(enum zio_checksum child, enum zio_checksum 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 enum zio_checksum
  99 zio_checksum_dedup_select(spa_t *spa, enum zio_checksum child,
 100     enum zio_checksum parent)
 101 {
 102         ASSERT((child & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
 103         ASSERT((parent & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
 104         ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
 105
 106         if (child == ZIO_CHECKSUM_INHERIT)
 107                 return (parent);
 108
 109         if (child == ZIO_CHECKSUM_ON)
 110                 return (spa_dedup_checksum(spa));
 111
 112         if (child == (ZIO_CHECKSUM_ON | ZIO_CHECKSUM_VERIFY))
 113                 return (spa_dedup_checksum(spa) | ZIO_CHECKSUM_VERIFY);
 114
 115         ASSERT(zio_checksum_table[child & ZIO_CHECKSUM_MASK].ci_dedup ||
 116             (child & ZIO_CHECKSUM_VERIFY) || child == ZIO_CHECKSUM_OFF);
 117
 118         return (child);
 119 }
 120
 121 /*
 122  * Set the external verifier for a gang block based on <vdev, offset, txg>,
 123  * a tuple which is guaranteed to be unique for the life of the pool.
 124  */
 125 static void
 126 zio_checksum_gang_verifier(zio_cksum_t *zcp, blkptr_t *bp)
 127 {
 128         dva_t *dva = BP_IDENTITY(bp);
 129         uint64_t txg = BP_PHYSICAL_BIRTH(bp);
 130
 131         ASSERT(BP_IS_GANG(bp));
 132
 133         ZIO_SET_CHECKSUM(zcp, DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), txg, 0);
 134 }
 135
 136 /*
 137  * Set the external verifier for a label block based on its offset.
 138  * The vdev is implicit, and the txg is unknowable at pool open time --
 139  * hence the logic in vdev_uberblock_load() to find the most recent copy.
 140  */
 141 static void
 142 zio_checksum_label_verifier(zio_cksum_t *zcp, uint64_t offset)
 143 {
 144         ZIO_SET_CHECKSUM(zcp, offset, 0, 0, 0);
 145 }
 146
 147 /*
 148  * Generate the checksum.
 149  */
 150 void
 151 zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
 152         void *data, uint64_t size)
 153 {
 154         blkptr_t *bp = zio->io_bp;
 155         uint64_t offset = zio->io_offset;
 156         zio_checksum_info_t *ci = &zio_checksum_table[checksum];
 157         zio_cksum_t cksum;
 158
 159         ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS);
 160         ASSERT(ci->ci_func[0] != NULL);
 161
 162         if (ci->ci_eck) {
 163                 zio_eck_t *eck;
 164
 165                 if (checksum == ZIO_CHECKSUM_ZILOG2) {
 166                         zil_chain_t *zilc = data;
 167
 168                         size = P2ROUNDUP_TYPED(zilc->zc_nused, ZIL_MIN_BLKSZ,
 169                             uint64_t);
 170                         eck = &zilc->zc_eck;
 171                 } else {
 172                         eck = (zio_eck_t *)((char *)data + size) - 1;
 173                 }
 174                 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
 175                         zio_checksum_gang_verifier(&eck->zec_cksum, bp);
 176                 else if (checksum == ZIO_CHECKSUM_LABEL)
 177                         zio_checksum_label_verifier(&eck->zec_cksum, offset);
 178                 else
 179                         bp->blk_cksum = eck->zec_cksum;
 180                 eck->zec_magic = ZEC_MAGIC;
 181                 ci->ci_func[0](data, size, &cksum);
 182                 eck->zec_cksum = cksum;
 183         } else {
 184                 ci->ci_func[0](data, size, &bp->blk_cksum);
 185         }
 186 }
 187
 188 int
 189 zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info)
 190 {
 191         blkptr_t *bp = zio->io_bp;
 192         uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum :
 193             (BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
 194         int byteswap;
 195         int error;
 196         uint64_t size = (bp == NULL ? zio->io_size :
 197             (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp)));
 198         uint64_t offset = zio->io_offset;
 199         void *data = zio->io_data;
 200         zio_checksum_info_t *ci = &zio_checksum_table[checksum];
 201         zio_cksum_t actual_cksum, expected_cksum, verifier;
 202
 203         if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
 204                 return (EINVAL);
 205
 206         if (ci->ci_eck) {
 207                 zio_eck_t *eck;
 208
 209                 if (checksum == ZIO_CHECKSUM_ZILOG2) {
 210                         zil_chain_t *zilc = data;
 211                         uint64_t nused;
 212
 213                         eck = &zilc->zc_eck;
 214                         if (eck->zec_magic == ZEC_MAGIC)
 215                                 nused = zilc->zc_nused;
 216                         else if (eck->zec_magic == BSWAP_64(ZEC_MAGIC))
 217                                 nused = BSWAP_64(zilc->zc_nused);
 218                         else
 219                                 return (ECKSUM);
 220
 221                         if (nused > size)
 222                                 return (ECKSUM);
 223
 224                         size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t);
 225                 } else {
 226                         eck = (zio_eck_t *)((char *)data + size) - 1;
 227                 }
 228
 229                 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
 230                         zio_checksum_gang_verifier(&verifier, bp);
 231                 else if (checksum == ZIO_CHECKSUM_LABEL)
 232                         zio_checksum_label_verifier(&verifier, offset);
 233                 else
 234                         verifier = bp->blk_cksum;
 235
 236                 byteswap = (eck->zec_magic == BSWAP_64(ZEC_MAGIC));
 237
 238                 if (byteswap)
 239                         byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
 240
 241                 expected_cksum = eck->zec_cksum;
 242                 eck->zec_cksum = verifier;
 243                 ci->ci_func[byteswap](data, size, &actual_cksum);
 244                 eck->zec_cksum = expected_cksum;
 245
 246                 if (byteswap)
 247                         byteswap_uint64_array(&expected_cksum,
 248                             sizeof (zio_cksum_t));
 249         } else {
 250                 ASSERT(!BP_IS_GANG(bp));
 251                 byteswap = BP_SHOULD_BYTESWAP(bp);
 252                 expected_cksum = bp->blk_cksum;
 253                 ci->ci_func[byteswap](data, size, &actual_cksum);
 254         }
 255
 256         info->zbc_expected = expected_cksum;
 257         info->zbc_actual = actual_cksum;
 258         info->zbc_checksum_name = ci->ci_name;
 259         info->zbc_byteswapped = byteswap;
 260         info->zbc_injected = 0;
 261         info->zbc_has_cksum = 1;
 262
 263         if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
 264                 return (ECKSUM);
 265
 266         if (zio_injection_enabled && !zio->io_error &&
 267             (error = zio_handle_fault_injection(zio, ECKSUM)) != 0) {
 268
 269                 info->zbc_injected = 1;
 270                 return (error);
 271         }
 272
 273         return (0);
 274 }