text: /*
   * 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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2013 by Delphix. All rights reserved.
   * Copyright (c) 2013, Joyent, Inc. All rights reserved.
   */
  
  #include <sys/zfs_context.h>
  #include <sys/spa.h>
  #include <sys/zio.h>
  #include <sys/zio_checksum.h>
  #include <sys/zil.h>
  #include <zfs_fletcher.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 eight bits of the bp.
   * This gives us room for up to 256 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 by BP_GET_CHECKSUM(bp).
   */
  
  /*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, 0, "inherit"},
  	{{NULL,			NULL},			0, 0, 0, "on"},
  	{{zio_checksum_off,	zio_checksum_off},	0, 0, 0, "off"},
  	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 1, 0, "label"},
  	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 1, 0, "gang_header"},
  	{{fletcher_2_native,	fletcher_2_byteswap},	0, 1, 0, "zilog"},
  	{{fletcher_2_native,	fletcher_2_byteswap},	0, 0, 0, "fletcher2"},
  	{{fletcher_4_native,	fletcher_4_byteswap},	1, 0, 0, "fletcher4"},
  	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 0, 1, "sha256"},
  	{{fletcher_4_native,	fletcher_4_byteswap},	0, 1, 0, "zilog2"},
  	{{zio_checksum_off,	zio_checksum_off},	0, 0, 0, "noparity"},
  };
  
  enum zio_checksum
  zio_checksum_select(enum zio_checksum child, enum zio_checksum 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);
  }
  
  enum zio_checksum
  zio_checksum_dedup_select(spa_t *spa, enum zio_checksum child,
      enum zio_checksum parent)
  {
  	ASSERT((child & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
  	ASSERT((parent & ZIO_CHECKSUM_MASK) < 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 (spa_dedup_checksum(spa));
  
  	if (child == (ZIO_CHECKSUM_ON | ZIO_CHECKSUM_VERIFY))
  		return (spa_dedup_checksum(spa) | ZIO_CHECKSUM_VERIFY);
  
  	ASSERT(zio_checksum_table[child & ZIO_CHECKSUM_MASK].ci_dedup ||
  	    (child & ZIO_CHECKSUM_VERIFY) || child == ZIO_CHECKSUM_OFF);
  
  	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_PHYSICAL_BIRTH(bp);
  
  	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_checksum_info_t *ci = &zio_checksum_table[checksum];
  	zio_cksum_t cksum;
  
  	ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS);
  	ASSERT(ci->ci_func[0] != NULL);
  
  	if (ci->ci_eck) {
  		zio_eck_t *eck;
  
  		if (checksum == ZIO_CHECKSUM_ZILOG2) {
  			zil_chain_t *zilc = data;
  
  			size = P2ROUNDUP_TYPED(zilc->zc_nused, ZIL_MIN_BLKSZ,
  			    uint64_t);
  			eck = &zilc->zc_eck;
  		} else {
  			eck = (zio_eck_t *)((char *)data + size) - 1;
  		}
  		if (checksum == ZIO_CHECKSUM_GANG_HEADER)
  			zio_checksum_gang_verifier(&eck->zec_cksum, bp);
  		else if (checksum == ZIO_CHECKSUM_LABEL)
  			zio_checksum_label_verifier(&eck->zec_cksum, offset);
  		else
  			bp->blk_cksum = eck->zec_cksum;
  		eck->zec_magic = ZEC_MAGIC;
  		ci->ci_func[0](data, size, &cksum);
  		eck->zec_cksum = cksum;
  	} else {
  		ci->ci_func[0](data, size, &bp->blk_cksum);
  	}
  }
  
  int
  zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info)
  {
  	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;
  	int error;
  	uint64_t size = (bp == NULL ? zio->io_size :
  	    (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp)));
  	uint64_t offset = zio->io_offset;
  	void *data = zio->io_data;
  	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 (SET_ERROR(EINVAL));
  
  	if (ci->ci_eck) {
  		zio_eck_t *eck;
  
  		if (checksum == ZIO_CHECKSUM_ZILOG2) {
  			zil_chain_t *zilc = data;
  			uint64_t nused;
  
  			eck = &zilc->zc_eck;
  			if (eck->zec_magic == ZEC_MAGIC)
  				nused = zilc->zc_nused;
  			else if (eck->zec_magic == BSWAP_64(ZEC_MAGIC))
  				nused = BSWAP_64(zilc->zc_nused);
  			else
  				return (SET_ERROR(ECKSUM));
  
  			if (nused > size)
  				return (SET_ERROR(ECKSUM));
  
  			size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t);
  		} else {
  			eck = (zio_eck_t *)((char *)data + size) - 1;
  		}
  
  		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 = (eck->zec_magic == BSWAP_64(ZEC_MAGIC));
  
  		if (byteswap)
  			byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
  
  		expected_cksum = eck->zec_cksum;
  		eck->zec_cksum = verifier;
  		ci->ci_func[byteswap](data, size, &actual_cksum);
  		eck->zec_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);
  	}
  
  	info->zbc_expected = expected_cksum;
  	info->zbc_actual = actual_cksum;
  	info->zbc_checksum_name = ci->ci_name;
  	info->zbc_byteswapped = byteswap;
  	info->zbc_injected = 0;
  	info->zbc_has_cksum = 1;
  
  	if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
  		return (SET_ERROR(ECKSUM));
  
  	if (zio_injection_enabled && !zio->io_error &&
  	    (error = zio_handle_fault_injection(zio, ECKSUM)) != 0) {
  
  		info->zbc_injected = 1;
  		return (error);
  	}
  
  	return (0);
  }
  