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.
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.
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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
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22 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
26 #pragma ident "@(#)zio_checksum.c 1.6 06/11/10 SMI"
28 #include <sys/zfs_context.h>
31 #include <sys/zio_checksum.h>
36 * In the SPA, everything is checksummed. We support checksum vectors
37 * for three distinct reasons:
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.
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.
50 * 3. If someone develops hardware that can compute a strong hash quickly,
51 * we want the ability to take advantage of that hardware.
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.
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.
65 zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)
67 ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
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"},
83 zio_checksum_select(uint8_t child, uint8_t parent)
85 ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);
86 ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);
87 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
89 if (child == ZIO_CHECKSUM_INHERIT)
92 if (child == ZIO_CHECKSUM_ON)
93 return (ZIO_CHECKSUM_ON_VALUE);
99 * Generate the checksum.
102 zio_checksum(uint_t checksum, zio_cksum_t *zcp, void *data, uint64_t size)
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;
108 ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);
109 ASSERT(ci->ci_func[0] != NULL);
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;
117 ci->ci_func[0](data, size, zcp);
122 zio_checksum_error(zio_t *zio)
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 :
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;
135 if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
139 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
140 zio_set_gang_verifier(zio, &zc);
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));
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));
154 expected_cksum = zbt->zbt_cksum;
156 ci->ci_func[0](data, size, &actual_cksum);
157 zbt->zbt_cksum = expected_cksum;
161 ASSERT(!BP_IS_GANG(bp));
162 ci->ci_func[byteswap](data, size, &actual_cksum);
165 if (!ZIO_CHECKSUM_EQUAL(actual_cksum, zc))
168 if (zio_injection_enabled && !zio->io_error)
169 return (zio_handle_fault_injection(zio, ECKSUM));