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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/zio.h>
#include <sys/zio_checksum.h>
/*
* Checksum vectors.
*
* In the SPA, everything is checksummed. We support checksum vectors
* for three distinct reasons:
*
* 1. Different kinds of data need different levels of protection.
* For SPA metadata, we always want a very strong checksum.
* For user data, we let users make the trade-off between speed
* and checksum strength.
*
* 2. Cryptographic hash and MAC algorithms are an area of active research.
* It is likely that in future hash functions will be at least as strong
* as current best-of-breed, and may be substantially faster as well.
* We want the ability to take advantage of these new hashes as soon as
* they become available.
*
* 3. If someone develops hardware that can compute a strong hash quickly,
* we want the ability to take advantage of that hardware.
*
* Of course, we don't want a checksum upgrade to invalidate existing
* data, so we store the checksum *function* in five bits of the DVA.
* This gives us room for up to 32 different checksum functions.
*
* When writing a block, we always checksum it with the latest-and-greatest
* checksum function of the appropriate strength. When reading a block,
* we compare the expected checksum against the actual checksum, which we
* compute via the checksum function specified in the DVA encoding.
*/
/*ARGSUSED*/
static void
zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)
{
ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
}
zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
{{NULL, NULL}, 0, 0, "inherit"},
{{NULL, NULL}, 0, 0, "on"},
{{zio_checksum_off, zio_checksum_off}, 0, 0, "off"},
{{zio_checksum_SHA256, zio_checksum_SHA256}, 1, 1, "label"},
{{zio_checksum_SHA256, zio_checksum_SHA256}, 1, 1, "gang_header"},
{{fletcher_2_native, fletcher_2_byteswap}, 0, 1, "zilog"},
{{fletcher_2_native, fletcher_2_byteswap}, 0, 0, "fletcher2"},
{{fletcher_4_native, fletcher_4_byteswap}, 1, 0, "fletcher4"},
{{zio_checksum_SHA256, zio_checksum_SHA256}, 1, 0, "SHA256"},
};
uint8_t
zio_checksum_select(uint8_t child, uint8_t parent)
{
ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);
ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);
ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
if (child == ZIO_CHECKSUM_INHERIT)
return (parent);
if (child == ZIO_CHECKSUM_ON)
return (ZIO_CHECKSUM_ON_VALUE);
return (child);
}
/*
* Set the external verifier for a gang block based on <vdev, offset, txg>,
* a tuple which is guaranteed to be unique for the life of the pool.
*/
static void
zio_checksum_gang_verifier(zio_cksum_t *zcp, blkptr_t *bp)
{
dva_t *dva = BP_IDENTITY(bp);
uint64_t txg = bp->blk_birth;
ASSERT(BP_IS_GANG(bp));
ZIO_SET_CHECKSUM(zcp, DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), txg, 0);
}
/*
* Set the external verifier for a label block based on its offset.
* The vdev is implicit, and the txg is unknowable at pool open time --
* hence the logic in vdev_uberblock_load() to find the most recent copy.
*/
static void
zio_checksum_label_verifier(zio_cksum_t *zcp, uint64_t offset)
{
ZIO_SET_CHECKSUM(zcp, offset, 0, 0, 0);
}
/*
* Generate the checksum.
*/
void
zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
void *data, uint64_t size)
{
blkptr_t *bp = zio->io_bp;
uint64_t offset = zio->io_offset;
zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;
zio_checksum_info_t *ci = &zio_checksum_table[checksum];
zio_cksum_t zbt_cksum;
ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS);
ASSERT(ci->ci_func[0] != NULL);
if (ci->ci_zbt) {
if (checksum == ZIO_CHECKSUM_GANG_HEADER)
zio_checksum_gang_verifier(&zbt->zbt_cksum, bp);
else if (checksum == ZIO_CHECKSUM_LABEL)
zio_checksum_label_verifier(&zbt->zbt_cksum, offset);
else
bp->blk_cksum = zbt->zbt_cksum;
zbt->zbt_magic = ZBT_MAGIC;
ci->ci_func[0](data, size, &zbt_cksum);
zbt->zbt_cksum = zbt_cksum;
} else {
ci->ci_func[0](data, size, &bp->blk_cksum);
}
}
int
zio_checksum_error(zio_t *zio)
{
blkptr_t *bp = zio->io_bp;
uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum :
(BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
int byteswap;
void *data = zio->io_data;
uint64_t size = (bp == NULL ? zio->io_size :
(BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp)));
uint64_t offset = zio->io_offset;
zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;
zio_checksum_info_t *ci = &zio_checksum_table[checksum];
zio_cksum_t actual_cksum, expected_cksum, verifier;
if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
return (EINVAL);
if (ci->ci_zbt) {
if (checksum == ZIO_CHECKSUM_GANG_HEADER)
zio_checksum_gang_verifier(&verifier, bp);
else if (checksum == ZIO_CHECKSUM_LABEL)
zio_checksum_label_verifier(&verifier, offset);
else
verifier = bp->blk_cksum;
byteswap = (zbt->zbt_magic == BSWAP_64(ZBT_MAGIC));
if (byteswap)
byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
expected_cksum = zbt->zbt_cksum;
zbt->zbt_cksum = verifier;
ci->ci_func[byteswap](data, size, &actual_cksum);
zbt->zbt_cksum = expected_cksum;
if (byteswap)
byteswap_uint64_array(&expected_cksum,
sizeof (zio_cksum_t));
} else {
ASSERT(!BP_IS_GANG(bp));
byteswap = BP_SHOULD_BYTESWAP(bp);
expected_cksum = bp->blk_cksum;
ci->ci_func[byteswap](data, size, &actual_cksum);
}
if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
return (ECKSUM);
if (zio_injection_enabled && !zio->io_error)
return (zio_handle_fault_injection(zio, ECKSUM));
return (0);
}
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