/*-
 *   BSD LICENSE
 *
 *   Copyright (c) Intel Corporation.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "spdk/dif.h"
#include "spdk/crc16.h"
#include "spdk/endian.h"
#include "spdk/log.h"
#include "spdk/util.h"

/* Context to iterate a iovec array. */
struct _iov_iter {
	/* Current iovec in the iteration */
	struct iovec *iov;

	/* Remaining count of iovecs in the iteration. */
	int iovcnt;

	/* Current offset in the iovec */
	uint32_t iov_offset;
};

static inline void
_iov_iter_init(struct _iov_iter *i, struct iovec *iovs, int iovcnt)
{
	i->iov = iovs;
	i->iovcnt = iovcnt;
	i->iov_offset = 0;
}

static inline void
_iov_iter_advance(struct _iov_iter *i, uint32_t step)
{
	i->iov_offset += step;
	if (i->iov_offset == i->iov->iov_len) {
		i->iov++;
		assert(i->iovcnt > 0);
		i->iovcnt--;
		i->iov_offset = 0;
	}
}

static inline void
_iov_iter_get_buf(struct _iov_iter *i, void **_buf, uint32_t *_buf_len)
{
	if (_buf != NULL) {
		*_buf = i->iov->iov_base + i->iov_offset;
	}
	if (_buf_len != NULL) {
		*_buf_len = i->iov->iov_len - i->iov_offset;
	}
}

static void
_iov_iter_fast_forward(struct _iov_iter *i, uint32_t offset)
{
	i->iov_offset = offset;
	while (i->iovcnt != 0) {
		if (i->iov_offset < i->iov->iov_len) {
			break;
		}

		i->iov_offset -= i->iov->iov_len;
		i->iov++;
		i->iovcnt--;
	}
}

static bool
_are_iovs_bytes_multiple(struct iovec *iovs, int iovcnt, uint32_t bytes)
{
	int i;

	for (i = 0; i < iovcnt; i++) {
		if (iovs[i].iov_len % bytes) {
			return false;
		}
	}

	return true;
}

static bool
_are_iovs_valid(struct iovec *iovs, int iovcnt, uint32_t bytes)
{
	uint64_t total = 0;
	int i;

	for (i = 0; i < iovcnt; i++) {
		total += iovs[i].iov_len;
	}

	return total >= bytes;
}

static bool
_dif_type_is_valid(enum spdk_dif_type dif_type, uint32_t dif_flags)
{
	switch (dif_type) {
	case SPDK_DIF_TYPE1:
	case SPDK_DIF_TYPE2:
	case SPDK_DIF_DISABLE:
		break;
	case SPDK_DIF_TYPE3:
		if (dif_flags & SPDK_DIF_FLAGS_REFTAG_CHECK) {
			SPDK_ERRLOG("Reference Tag should not be checked for Type 3\n");
			return false;
		}
		break;
	default:
		SPDK_ERRLOG("Unknown DIF Type: %d\n", dif_type);
		return false;
	}

	return true;
}

static bool
_dif_is_disabled(enum spdk_dif_type dif_type)
{
	if (dif_type == SPDK_DIF_DISABLE) {
		return true;
	} else {
		return false;
	}
}


static uint32_t
_get_guard_interval(uint32_t block_size, uint32_t md_size, bool dif_loc, bool md_interleave)
{
	if (!dif_loc) {
		/* For metadata formats with more than 8 bytes, if the DIF is
		 * contained in the last 8 bytes of metadata, then the CRC
		 * covers all metadata up to but excluding these last 8 bytes.
		 */
		if (md_interleave) {
			return block_size - sizeof(struct spdk_dif);
		} else {
			return md_size - sizeof(struct spdk_dif);
		}
	} else {
		/* For metadata formats with more than 8 bytes, if the DIF is
		 * contained in the first 8 bytes of metadata, then the CRC
		 * does not cover any metadata.
		 */
		if (md_interleave) {
			return block_size - md_size;
		} else {
			return 0;
		}
	}
}

int
spdk_dif_ctx_init(struct spdk_dif_ctx *ctx, uint32_t block_size, uint32_t md_size,
		  bool md_interleave, bool dif_loc, enum spdk_dif_type dif_type, uint32_t dif_flags,
		  uint32_t init_ref_tag, uint16_t apptag_mask, uint16_t app_tag)
{
	if (md_size < sizeof(struct spdk_dif)) {
		SPDK_ERRLOG("Metadata size is smaller than DIF size.\n");
		return -EINVAL;
	}

	if (md_interleave) {
		if (block_size < md_size) {
			SPDK_ERRLOG("Block size is smaller than DIF size.\n");
			return -EINVAL;
		}
	} else {
		if (block_size == 0 || (block_size % 512) != 0) {
			SPDK_ERRLOG("Zero block size is not allowed\n");
			return -EINVAL;
		}
	}

	if (!_dif_type_is_valid(dif_type, dif_flags)) {
		SPDK_ERRLOG("DIF type is invalid.\n");
		return -EINVAL;
	}

	ctx->block_size = block_size;
	ctx->md_size = md_size;
	ctx->guard_interval = _get_guard_interval(block_size, md_size, dif_loc, md_interleave);
	ctx->dif_type = dif_type;
	ctx->dif_flags = dif_flags;
	ctx->init_ref_tag = init_ref_tag;
	ctx->apptag_mask = apptag_mask;
	ctx->app_tag = app_tag;

	return 0;
}

static void
_dif_generate(void *_dif, uint16_t guard, uint32_t offset_blocks,
	      const struct spdk_dif_ctx *ctx)
{
	struct spdk_dif *dif = _dif;
	uint32_t ref_tag;

	if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
		to_be16(&dif->guard, guard);
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_APPTAG_CHECK) {
		to_be16(&dif->app_tag, ctx->app_tag);
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_REFTAG_CHECK) {
		/* For type 1 and 2, the reference tag is incremented for each
		 * subsequent logical block. For type 3, the reference tag
		 * remains the same as the initial reference tag.
		 */
		if (ctx->dif_type != SPDK_DIF_TYPE3) {
			ref_tag = ctx->init_ref_tag + offset_blocks;
		} else {
			ref_tag = ctx->init_ref_tag;
		}

		to_be32(&dif->ref_tag, ref_tag);
	}
}

static void
dif_generate(struct iovec *iovs, int iovcnt, uint32_t num_blocks,
	     const struct spdk_dif_ctx *ctx)
{
	struct _iov_iter iter;
	uint32_t offset_blocks;
	void *buf;
	uint16_t guard = 0;

	offset_blocks = 0;
	_iov_iter_init(&iter, iovs, iovcnt);

	while (offset_blocks < num_blocks) {
		_iov_iter_get_buf(&iter, &buf, NULL);

		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif(0, buf, ctx->guard_interval);
		}

		_dif_generate(buf + ctx->guard_interval, guard, offset_blocks, ctx);

		_iov_iter_advance(&iter, ctx->block_size);
		offset_blocks++;
	}
}

static void
_dif_generate_split(struct _iov_iter *iter, uint32_t offset_blocks,
		    const struct spdk_dif_ctx *ctx)
{
	uint32_t offset_in_block, offset_in_dif, buf_len;
	void *buf;
	uint16_t guard;
	struct spdk_dif dif = {};

	guard = 0;
	offset_in_block = 0;

	while (offset_in_block < ctx->block_size) {
		_iov_iter_get_buf(iter, &buf, &buf_len);

		if (offset_in_block < ctx->guard_interval) {
			buf_len = spdk_min(buf_len, ctx->guard_interval - offset_in_block);

			if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
				/* Compute CRC over split logical block data. */
				guard = spdk_crc16_t10dif(guard, buf, buf_len);
			}

			if (offset_in_block + buf_len == ctx->guard_interval) {
				/* If a whole logical block data is parsed, generate DIF
				 * and save it to the temporary DIF area.
				 */
				_dif_generate(&dif, guard, offset_blocks, ctx);
			}
		} else if (offset_in_block < ctx->guard_interval + sizeof(struct spdk_dif)) {
			/* Copy generated DIF to the split DIF field. */
			offset_in_dif = offset_in_block - ctx->guard_interval;
			buf_len = spdk_min(buf_len, sizeof(struct spdk_dif) - offset_in_dif);

			memcpy(buf, ((uint8_t *)&dif) + offset_in_dif, buf_len);
		} else {
			/* Skip metadata field after DIF field. */
			buf_len = spdk_min(buf_len, ctx->block_size - offset_in_block);
		}

		_iov_iter_advance(iter, buf_len);
		offset_in_block += buf_len;
	}
}

static void
dif_generate_split(struct iovec *iovs, int iovcnt, uint32_t num_blocks,
		   const struct spdk_dif_ctx *ctx)
{
	struct _iov_iter iter;
	uint32_t offset_blocks;

	offset_blocks = 0;
	_iov_iter_init(&iter, iovs, iovcnt);

	while (offset_blocks < num_blocks) {
		_dif_generate_split(&iter, offset_blocks, ctx);
		offset_blocks++;
	}
}

int
spdk_dif_generate(struct iovec *iovs, int iovcnt, uint32_t num_blocks,
		  const struct spdk_dif_ctx *ctx)
{
	if (!_are_iovs_valid(iovs, iovcnt, ctx->block_size * num_blocks)) {
		SPDK_ERRLOG("Size of iovec array is not valid.\n");
		return -EINVAL;
	}

	if (_dif_is_disabled(ctx->dif_type)) {
		return 0;
	}

	if (_are_iovs_bytes_multiple(iovs, iovcnt, ctx->block_size)) {
		dif_generate(iovs, iovcnt, num_blocks, ctx);
	} else {
		dif_generate_split(iovs, iovcnt, num_blocks, ctx);
	}

	return 0;
}

static void
_dif_error_set(struct spdk_dif_error *err_blk, uint8_t err_type,
	       uint32_t expected, uint32_t actual, uint32_t err_offset)
{
	if (err_blk) {
		err_blk->err_type = err_type;
		err_blk->expected = expected;
		err_blk->actual = actual;
		err_blk->err_offset = err_offset;
	}
}

static int
_dif_verify(void *_dif, uint16_t guard, uint32_t offset_blocks,
	    const struct spdk_dif_ctx *ctx, struct spdk_dif_error *err_blk)
{
	struct spdk_dif *dif = _dif;
	uint16_t _guard;
	uint16_t _app_tag;
	uint32_t ref_tag, _ref_tag;

	switch (ctx->dif_type) {
	case SPDK_DIF_TYPE1:
	case SPDK_DIF_TYPE2:
		/* If Type 1 or 2 is used, then all DIF checks are disabled when
		 * the Application Tag is 0xFFFF.
		 */
		if (dif->app_tag == 0xFFFF) {
			return 0;
		}
		break;
	case SPDK_DIF_TYPE3:
		/* If Type 3 is used, then all DIF checks are disabled when the
		 * Application Tag is 0xFFFF and the Reference Tag is 0xFFFFFFFF.
		 */
		if (dif->app_tag == 0xFFFF && dif->ref_tag == 0xFFFFFFFF) {
			return 0;
		}
		break;
	default:
		break;
	}

	/* For type 1 and 2, the reference tag is incremented for each
	 * subsequent logical block. For type 3, the reference tag
	 * remains the same as the initial reference tag.
	 */
	if (ctx->dif_type != SPDK_DIF_TYPE3) {
		ref_tag = ctx->init_ref_tag + offset_blocks;
	} else {
		ref_tag = ctx->init_ref_tag;
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
		/* Compare the DIF Guard field to the CRC computed over the logical
		 * block data.
		 */
		_guard = from_be16(&dif->guard);
		if (_guard != guard) {
			_dif_error_set(err_blk, SPDK_DIF_GUARD_ERROR, _guard, guard,
				       offset_blocks);
			SPDK_ERRLOG("Failed to compare Guard: LBA=%" PRIu32 "," \
				    "  Expected=%x, Actual=%x\n",
				    ref_tag, _guard, guard);
			return -1;
		}
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_APPTAG_CHECK) {
		/* Compare unmasked bits in the DIF Application Tag field to the
		 * passed Application Tag.
		 */
		_app_tag = from_be16(&dif->app_tag);
		if ((_app_tag & ctx->apptag_mask) != ctx->app_tag) {
			_dif_error_set(err_blk, SPDK_DIF_APPTAG_ERROR, ctx->app_tag,
				       (_app_tag & ctx->apptag_mask), offset_blocks);
			SPDK_ERRLOG("Failed to compare App Tag: LBA=%" PRIu32 "," \
				    "  Expected=%x, Actual=%x\n",
				    ref_tag, ctx->app_tag, (_app_tag & ctx->apptag_mask));
			return -1;
		}
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_REFTAG_CHECK) {
		switch (ctx->dif_type) {
		case SPDK_DIF_TYPE1:
		case SPDK_DIF_TYPE2:
			/* Compare the DIF Reference Tag field to the passed Reference Tag.
			 * The passed Reference Tag will be the least significant 4 bytes
			 * of the LBA when Type 1 is used, and application specific value
			 * if Type 2 is used,
			 */
			_ref_tag = from_be32(&dif->ref_tag);
			if (_ref_tag != ref_tag) {
				_dif_error_set(err_blk, SPDK_DIF_REFTAG_ERROR, ref_tag,
					       _ref_tag, offset_blocks);
				SPDK_ERRLOG("Failed to compare Ref Tag: LBA=%" PRIu32 "," \
					    " Expected=%x, Actual=%x\n",
					    ref_tag, ref_tag, _ref_tag);
				return -1;
			}
			break;
		case SPDK_DIF_TYPE3:
			/* For Type 3, computed Reference Tag remains unchanged.
			 * Hence ignore the Reference Tag field.
			 */
			break;
		default:
			break;
		}
	}

	return 0;
}

static int
dif_verify(struct iovec *iovs, int iovcnt, uint32_t num_blocks,
	   const struct spdk_dif_ctx *ctx, struct spdk_dif_error *err_blk)
{
	struct _iov_iter iter;
	uint32_t offset_blocks;
	int rc;
	void *buf;
	uint16_t guard = 0;

	offset_blocks = 0;
	_iov_iter_init(&iter, iovs, iovcnt);

	while (offset_blocks < num_blocks) {
		_iov_iter_get_buf(&iter, &buf, NULL);

		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif(0, buf, ctx->guard_interval);
		}

		rc = _dif_verify(buf + ctx->guard_interval, guard, offset_blocks, ctx, err_blk);
		if (rc != 0) {
			return rc;
		}

		_iov_iter_advance(&iter, ctx->block_size);
		offset_blocks++;
	}

	return 0;
}

static int
_dif_verify_split(struct _iov_iter *iter, uint32_t offset_blocks,
		  const struct spdk_dif_ctx *ctx, struct spdk_dif_error *err_blk)
{
	uint32_t offset_in_block, offset_in_dif, buf_len;
	void *buf;
	uint16_t guard;
	struct spdk_dif dif = {};

	guard = 0;
	offset_in_block = 0;

	while (offset_in_block < ctx->block_size) {
		_iov_iter_get_buf(iter, &buf, &buf_len);

		if (offset_in_block < ctx->guard_interval) {
			buf_len = spdk_min(buf_len, ctx->guard_interval - offset_in_block);

			if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
				/* Compute CRC over split logical block data. */
				guard = spdk_crc16_t10dif(guard, buf, buf_len);
			}
		} else if (offset_in_block < ctx->guard_interval + sizeof(struct spdk_dif)) {
			/* Copy the split DIF field to the temporary DIF buffer. */
			offset_in_dif = offset_in_block - ctx->guard_interval;
			buf_len = spdk_min(buf_len, sizeof(struct spdk_dif) - offset_in_dif);

			memcpy((uint8_t *)&dif + offset_in_dif, buf, buf_len);
		} else {
			/* Skip metadata field after DIF field. */
			buf_len = spdk_min(buf_len, ctx->block_size - offset_in_block);
		}

		_iov_iter_advance(iter, buf_len);
		offset_in_block += buf_len;
	}

	return _dif_verify(&dif, guard, offset_blocks, ctx, err_blk);
}

static int
dif_verify_split(struct iovec *iovs, int iovcnt, uint32_t num_blocks,
		 const struct spdk_dif_ctx *ctx, struct spdk_dif_error *err_blk)
{
	struct _iov_iter iter;
	uint32_t offset_blocks;
	int rc;

	offset_blocks = 0;
	_iov_iter_init(&iter, iovs, iovcnt);

	while (offset_blocks < num_blocks) {
		rc = _dif_verify_split(&iter, offset_blocks, ctx, err_blk);
		if (rc != 0) {
			return rc;
		}
		offset_blocks++;
	}

	return 0;
}

int
spdk_dif_verify(struct iovec *iovs, int iovcnt, uint32_t num_blocks,
		const struct spdk_dif_ctx *ctx, struct spdk_dif_error *err_blk)
{
	if (!_are_iovs_valid(iovs, iovcnt, ctx->block_size * num_blocks)) {
		SPDK_ERRLOG("Size of iovec array is not valid.\n");
		return -EINVAL;
	}

	if (_dif_is_disabled(ctx->dif_type)) {
		return 0;
	}

	if (_are_iovs_bytes_multiple(iovs, iovcnt, ctx->block_size)) {
		return dif_verify(iovs, iovcnt, num_blocks, ctx, err_blk);
	} else {
		return dif_verify_split(iovs, iovcnt, num_blocks, ctx, err_blk);
	}
}

static void
dif_generate_copy(struct iovec *iovs, int iovcnt, struct iovec *bounce_iov,
		  uint32_t num_blocks, const struct spdk_dif_ctx *ctx)
{
	struct _iov_iter src_iter, dst_iter;
	uint32_t offset_blocks, data_block_size;
	void *src, *dst;
	uint16_t guard;

	offset_blocks = 0;
	_iov_iter_init(&src_iter, iovs, iovcnt);
	_iov_iter_init(&dst_iter, bounce_iov, 1);

	data_block_size = ctx->block_size - ctx->md_size;

	while (offset_blocks < num_blocks) {

		_iov_iter_get_buf(&src_iter, &src, NULL);
		_iov_iter_get_buf(&dst_iter, &dst, NULL);

		guard = 0;
		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif_copy(0, dst, src, data_block_size);
			guard = spdk_crc16_t10dif(guard, dst + data_block_size,
						  ctx->guard_interval - data_block_size);
		} else {
			memcpy(dst, src, data_block_size);
		}

		_dif_generate(dst + ctx->guard_interval, guard, offset_blocks, ctx);

		_iov_iter_advance(&src_iter, data_block_size);
		_iov_iter_advance(&dst_iter, ctx->block_size);
		offset_blocks++;
	}
}

static void
_dif_generate_copy_split(struct _iov_iter *src_iter, struct _iov_iter *dst_iter,
			 uint32_t offset_blocks, const struct spdk_dif_ctx *ctx)
{
	uint32_t offset_in_block, src_len, data_block_size;
	uint16_t guard;
	void *src, *dst;

	_iov_iter_get_buf(dst_iter, &dst, NULL);

	data_block_size = ctx->block_size - ctx->md_size;

	guard = 0;
	offset_in_block = 0;

	while (offset_in_block < data_block_size) {
		/* Compute CRC over split logical block data and copy
		 * data to bounce buffer.
		 */
		_iov_iter_get_buf(src_iter, &src, &src_len);
		src_len = spdk_min(src_len, data_block_size - offset_in_block);

		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif_copy(guard, dst + offset_in_block,
						       src, src_len);
		} else {
			memcpy(dst + offset_in_block, src, src_len);
		}

		_iov_iter_advance(src_iter, src_len);
		offset_in_block += src_len;
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
		guard = spdk_crc16_t10dif(guard, dst + data_block_size,
					  ctx->guard_interval - data_block_size);
	}

	_iov_iter_advance(dst_iter, ctx->block_size);

	_dif_generate(dst + ctx->guard_interval, guard, offset_blocks, ctx);
}

static void
dif_generate_copy_split(struct iovec *iovs, int iovcnt, struct iovec *bounce_iov,
			uint32_t num_blocks, const struct spdk_dif_ctx *ctx)
{
	struct _iov_iter src_iter, dst_iter;
	uint32_t offset_blocks;

	offset_blocks = 0;
	_iov_iter_init(&src_iter, iovs, iovcnt);
	_iov_iter_init(&dst_iter, bounce_iov, 1);

	while (offset_blocks < num_blocks) {
		_dif_generate_copy_split(&src_iter, &dst_iter, offset_blocks, ctx);
		offset_blocks++;
	}
}

int
spdk_dif_generate_copy(struct iovec *iovs, int iovcnt, struct iovec *bounce_iov,
		       uint32_t num_blocks, const struct spdk_dif_ctx *ctx)
{
	uint32_t data_block_size;

	data_block_size = ctx->block_size - ctx->md_size;

	if (!_are_iovs_valid(iovs, iovcnt, data_block_size * num_blocks) ||
	    !_are_iovs_valid(bounce_iov, 1, ctx->block_size * num_blocks)) {
		SPDK_ERRLOG("Size of iovec arrays are not valid.\n");
		return -EINVAL;
	}

	if (_dif_is_disabled(ctx->dif_type)) {
		return 0;
	}

	if (_are_iovs_bytes_multiple(iovs, iovcnt, data_block_size)) {
		dif_generate_copy(iovs, iovcnt, bounce_iov, num_blocks, ctx);
	} else {
		dif_generate_copy_split(iovs, iovcnt, bounce_iov, num_blocks, ctx);
	}

	return 0;
}

static int
dif_verify_copy(struct iovec *iovs, int iovcnt, struct iovec *bounce_iov,
		uint32_t num_blocks, const struct spdk_dif_ctx *ctx,
		struct spdk_dif_error *err_blk)
{
	struct _iov_iter src_iter, dst_iter;
	uint32_t offset_blocks, data_block_size;
	void *src, *dst;
	int rc;
	uint16_t guard;

	offset_blocks = 0;
	_iov_iter_init(&src_iter, bounce_iov, 1);
	_iov_iter_init(&dst_iter, iovs, iovcnt);

	data_block_size = ctx->block_size - ctx->md_size;

	while (offset_blocks < num_blocks) {

		_iov_iter_get_buf(&src_iter, &src, NULL);
		_iov_iter_get_buf(&dst_iter, &dst, NULL);

		guard = 0;
		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif_copy(0, dst, src, data_block_size);
			guard = spdk_crc16_t10dif(guard, src + data_block_size,
						  ctx->guard_interval - data_block_size);
		} else {
			memcpy(dst, src, data_block_size);
		}

		rc = _dif_verify(src + ctx->guard_interval, guard, offset_blocks, ctx, err_blk);
		if (rc != 0) {
			return rc;
		}

		_iov_iter_advance(&src_iter, ctx->block_size);
		_iov_iter_advance(&dst_iter, data_block_size);
		offset_blocks++;
	}

	return 0;
}

static int
_dif_verify_copy_split(struct _iov_iter *src_iter, struct _iov_iter *dst_iter,
		       uint32_t offset_blocks, const struct spdk_dif_ctx *ctx,
		       struct spdk_dif_error *err_blk)
{
	uint32_t offset_in_block, dst_len, data_block_size;
	uint16_t guard;
	void *src, *dst;

	_iov_iter_get_buf(src_iter, &src, NULL);

	data_block_size = ctx->block_size - ctx->md_size;

	guard = 0;
	offset_in_block = 0;

	while (offset_in_block < data_block_size) {
		/* Compute CRC over split logical block data and copy
		 * data to bounce buffer.
		 */
		_iov_iter_get_buf(dst_iter, &dst, &dst_len);
		dst_len = spdk_min(dst_len, data_block_size - offset_in_block);

		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif_copy(guard, dst,
						       src + offset_in_block, dst_len);
		} else {
			memcpy(dst, src + offset_in_block, dst_len);
		}

		_iov_iter_advance(dst_iter, dst_len);
		offset_in_block += dst_len;
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
		guard = spdk_crc16_t10dif(guard, src + data_block_size,
					  ctx->guard_interval - data_block_size);
	}

	_iov_iter_advance(src_iter, ctx->block_size);

	return _dif_verify(src + ctx->guard_interval, guard, offset_blocks, ctx, err_blk);
}

static int
dif_verify_copy_split(struct iovec *iovs, int iovcnt, struct iovec *bounce_iov,
		      uint32_t num_blocks, const struct spdk_dif_ctx *ctx,
		      struct spdk_dif_error *err_blk)
{
	struct _iov_iter src_iter, dst_iter;
	uint32_t offset_blocks;
	int rc;

	offset_blocks = 0;
	_iov_iter_init(&src_iter, bounce_iov, 1);
	_iov_iter_init(&dst_iter, iovs, iovcnt);

	while (offset_blocks < num_blocks) {
		rc = _dif_verify_copy_split(&src_iter, &dst_iter, offset_blocks, ctx, err_blk);
		if (rc != 0) {
			return rc;
		}
		offset_blocks++;
	}

	return 0;
}

int
spdk_dif_verify_copy(struct iovec *iovs, int iovcnt, struct iovec *bounce_iov,
		     uint32_t num_blocks, const struct spdk_dif_ctx *ctx,
		     struct spdk_dif_error *err_blk)
{
	uint32_t data_block_size;

	data_block_size = ctx->block_size - ctx->md_size;

	if (!_are_iovs_valid(iovs, iovcnt, data_block_size * num_blocks) ||
	    !_are_iovs_valid(bounce_iov, 1, ctx->block_size * num_blocks)) {
		SPDK_ERRLOG("Size of iovec arrays are not valid\n");
		return -EINVAL;
	}

	if (_dif_is_disabled(ctx->dif_type)) {
		return 0;
	}

	if (_are_iovs_bytes_multiple(iovs, iovcnt, data_block_size)) {
		return dif_verify_copy(iovs, iovcnt, bounce_iov, num_blocks, ctx, err_blk);
	} else {
		return dif_verify_copy_split(iovs, iovcnt, bounce_iov, num_blocks, ctx, err_blk);
	}
}

static void
_bit_flip(uint8_t *buf, uint32_t flip_bit)
{
	uint8_t byte;

	byte = *buf;
	byte ^= 1 << flip_bit;
	*buf = byte;
}

static int
_dif_inject_error(struct iovec *iovs, int iovcnt,
		  uint32_t block_size, uint32_t num_blocks,
		  uint32_t inject_offset_blocks,
		  uint32_t inject_offset_bytes,
		  uint32_t inject_offset_bits)
{
	struct _iov_iter iter;
	uint32_t offset_in_block, buf_len;
	void *buf;

	_iov_iter_init(&iter, iovs, iovcnt);

	_iov_iter_fast_forward(&iter, block_size * inject_offset_blocks);

	offset_in_block = 0;

	while (offset_in_block < block_size) {
		_iov_iter_get_buf(&iter, &buf, &buf_len);
		buf_len = spdk_min(buf_len, block_size - offset_in_block);

		if (inject_offset_bytes >= offset_in_block &&
		    inject_offset_bytes < offset_in_block + buf_len) {
			buf += inject_offset_bytes - offset_in_block;
			_bit_flip(buf, inject_offset_bits);
			return 0;
		}

		_iov_iter_advance(&iter, buf_len);
		offset_in_block += buf_len;
	}

	return -1;
}

static int
dif_inject_error(struct iovec *iovs, int iovcnt,
		 uint32_t block_size, uint32_t num_blocks,
		 uint32_t start_inject_bytes, uint32_t inject_range_bytes,
		 uint32_t *inject_offset)
{
	uint32_t inject_offset_blocks, inject_offset_bytes, inject_offset_bits;
	uint32_t offset_blocks;
	int rc;

	srand(time(0));

	inject_offset_blocks = rand() % num_blocks;
	inject_offset_bytes = start_inject_bytes + (rand() % inject_range_bytes);
	inject_offset_bits = rand() % 8;

	for (offset_blocks = 0; offset_blocks < num_blocks; offset_blocks++) {
		if (offset_blocks == inject_offset_blocks) {
			rc = _dif_inject_error(iovs, iovcnt, block_size, num_blocks,
					       inject_offset_blocks,
					       inject_offset_bytes,
					       inject_offset_bits);
			if (rc == 0) {
				*inject_offset = inject_offset_blocks;
			}
			return rc;
		}
	}

	return -1;
}

#define _member_size(type, member)	sizeof(((type *)0)->member)

int
spdk_dif_inject_error(struct iovec *iovs, int iovcnt, uint32_t num_blocks,
		      const struct spdk_dif_ctx *ctx, uint32_t inject_flags,
		      uint32_t *inject_offset)
{
	int rc;

	if (!_are_iovs_valid(iovs, iovcnt, ctx->block_size * num_blocks)) {
		SPDK_ERRLOG("Size of iovec array is not valid.\n");
		return -EINVAL;
	}

	if (inject_flags & SPDK_DIF_REFTAG_ERROR) {
		rc = dif_inject_error(iovs, iovcnt, ctx->block_size, num_blocks,
				      ctx->guard_interval + offsetof(struct spdk_dif, ref_tag),
				      _member_size(struct spdk_dif, ref_tag),
				      inject_offset);
		if (rc != 0) {
			SPDK_ERRLOG("Failed to inject error to Reference Tag.\n");
			return rc;
		}
	}

	if (inject_flags & SPDK_DIF_APPTAG_ERROR) {
		rc = dif_inject_error(iovs, iovcnt, ctx->block_size, num_blocks,
				      ctx->guard_interval + offsetof(struct spdk_dif, app_tag),
				      _member_size(struct spdk_dif, app_tag),
				      inject_offset);
		if (rc != 0) {
			SPDK_ERRLOG("Failed to inject error to Application Tag.\n");
			return rc;
		}
	}
	if (inject_flags & SPDK_DIF_GUARD_ERROR) {
		rc = dif_inject_error(iovs, iovcnt, ctx->block_size, num_blocks,
				      ctx->guard_interval,
				      _member_size(struct spdk_dif, guard),
				      inject_offset);
		if (rc != 0) {
			SPDK_ERRLOG("Failed to inject error to Guard.\n");
			return rc;
		}
	}

	if (inject_flags & SPDK_DIF_DATA_ERROR) {
		/* If the DIF information is contained within the last 8 bytes of
		 * metadata, then the CRC covers all metadata bytes up to but excluding
		 * the last 8 bytes. But error injection does not cover these metadata
		 * because classification is not determined yet.
		 *
		 * Note: Error injection to data block is expected to be detected as
		 * guard error.
		 */
		rc = dif_inject_error(iovs, iovcnt, ctx->block_size, num_blocks,
				      0,
				      ctx->block_size - ctx->md_size,
				      inject_offset);
		if (rc != 0) {
			SPDK_ERRLOG("Failed to inject error to data block.\n");
			return rc;
		}
	}

	return 0;
}

static void
dix_generate(struct iovec *iovs, int iovcnt, struct iovec *md_iov,
	     uint32_t num_blocks, const struct spdk_dif_ctx *ctx)
{
	struct _iov_iter data_iter, md_iter;
	uint32_t offset_blocks;
	uint16_t guard;
	void *data_buf, *md_buf;

	offset_blocks = 0;
	_iov_iter_init(&data_iter, iovs, iovcnt);
	_iov_iter_init(&md_iter, md_iov, 1);

	while (offset_blocks < num_blocks) {

		_iov_iter_get_buf(&data_iter, &data_buf, NULL);
		_iov_iter_get_buf(&md_iter, &md_buf, NULL);

		guard = 0;
		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif(0, data_buf, ctx->block_size);
			guard = spdk_crc16_t10dif(guard, md_buf, ctx->guard_interval);
		}

		_dif_generate(md_buf + ctx->guard_interval, guard, offset_blocks, ctx);

		_iov_iter_advance(&data_iter, ctx->block_size);
		_iov_iter_advance(&md_iter, ctx->md_size);
		offset_blocks++;
	}
}

static void
_dix_generate_split(struct _iov_iter *data_iter, struct _iov_iter *md_iter,
		    uint32_t offset_blocks, const struct spdk_dif_ctx *ctx)
{
	uint32_t offset_in_block, data_buf_len;
	uint16_t guard;
	void *data_buf, *md_buf;

	_iov_iter_get_buf(md_iter, &md_buf, NULL);

	guard = 0;
	offset_in_block = 0;

	while (offset_in_block < ctx->block_size) {
		_iov_iter_get_buf(data_iter, &data_buf, &data_buf_len);
		data_buf_len = spdk_min(data_buf_len, ctx->block_size - offset_in_block);

		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif(guard, data_buf, data_buf_len);
		}

		_iov_iter_advance(data_iter, data_buf_len);
		offset_in_block += data_buf_len;
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
		guard = spdk_crc16_t10dif(guard, md_buf, ctx->guard_interval);
	}

	_iov_iter_advance(md_iter, ctx->md_size);

	_dif_generate(md_buf + ctx->guard_interval, guard, offset_blocks, ctx);
}

static void
dix_generate_split(struct iovec *iovs, int iovcnt, struct iovec *md_iov,
		   uint32_t num_blocks, const struct spdk_dif_ctx *ctx)
{
	struct _iov_iter data_iter, md_iter;
	uint32_t offset_blocks;

	offset_blocks = 0;
	_iov_iter_init(&data_iter, iovs, iovcnt);
	_iov_iter_init(&md_iter, md_iov, 1);

	while (offset_blocks < num_blocks) {
		_dix_generate_split(&data_iter, &md_iter, offset_blocks, ctx);
		offset_blocks++;
	}
}

int
spdk_dix_generate(struct iovec *iovs, int iovcnt, struct iovec *md_iov,
		  uint32_t num_blocks, const struct spdk_dif_ctx *ctx)
{
	if (!_are_iovs_valid(iovs, iovcnt, ctx->block_size * num_blocks) ||
	    !_are_iovs_valid(md_iov, 1, ctx->md_size * num_blocks)) {
		SPDK_ERRLOG("Size of iovec array is not valid.\n");
		return -EINVAL;
	}

	if (_dif_is_disabled(ctx->dif_type)) {
		return 0;
	}

	if (_are_iovs_bytes_multiple(iovs, iovcnt, ctx->block_size)) {
		dix_generate(iovs, iovcnt, md_iov, num_blocks, ctx);
	} else {
		dix_generate_split(iovs, iovcnt, md_iov, num_blocks, ctx);
	}

	return 0;
}

static int
dix_verify(struct iovec *iovs, int iovcnt, struct iovec *md_iov,
	   uint32_t num_blocks, const struct spdk_dif_ctx *ctx,
	   struct spdk_dif_error *err_blk)
{
	struct _iov_iter data_iter, md_iter;
	uint32_t offset_blocks;
	uint16_t guard;
	void *data_buf, *md_buf;
	int rc;

	offset_blocks = 0;
	_iov_iter_init(&data_iter, iovs, iovcnt);
	_iov_iter_init(&md_iter, md_iov, 1);

	while (offset_blocks < num_blocks) {

		_iov_iter_get_buf(&data_iter, &data_buf, NULL);
		_iov_iter_get_buf(&md_iter, &md_buf, NULL);

		guard = 0;
		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif(0, data_buf, ctx->block_size);
			guard = spdk_crc16_t10dif(guard, md_buf, ctx->guard_interval);
		}

		rc = _dif_verify(md_buf + ctx->guard_interval, guard, offset_blocks, ctx, err_blk);
		if (rc != 0) {
			return rc;
		}

		_iov_iter_advance(&data_iter, ctx->block_size);
		_iov_iter_advance(&md_iter, ctx->md_size);
		offset_blocks++;
	}

	return 0;
}

static int
_dix_verify_split(struct _iov_iter *data_iter, struct _iov_iter *md_iter,
		  uint32_t offset_blocks, const struct spdk_dif_ctx *ctx,
		  struct spdk_dif_error *err_blk)
{
	uint32_t offset_in_block, data_buf_len;
	uint16_t guard;
	void *data_buf, *md_buf;

	_iov_iter_get_buf(md_iter, &md_buf, NULL);

	guard = 0;
	offset_in_block = 0;

	while (offset_in_block < ctx->block_size) {
		_iov_iter_get_buf(data_iter, &data_buf, &data_buf_len);
		data_buf_len = spdk_min(data_buf_len, ctx->block_size - offset_in_block);

		if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
			guard = spdk_crc16_t10dif(guard, data_buf, data_buf_len);
		}

		_iov_iter_advance(data_iter, data_buf_len);
		offset_in_block += data_buf_len;
	}

	if (ctx->dif_flags & SPDK_DIF_FLAGS_GUARD_CHECK) {
		guard = spdk_crc16_t10dif(guard, md_buf, ctx->guard_interval);
	}

	_iov_iter_advance(md_iter, ctx->md_size);

	return _dif_verify(md_buf + ctx->guard_interval, guard, offset_blocks, ctx, err_blk);
}

static int
dix_verify_split(struct iovec *iovs, int iovcnt, struct iovec *md_iov,
		 uint32_t num_blocks, const struct spdk_dif_ctx *ctx,
		 struct spdk_dif_error *err_blk)
{
	struct _iov_iter data_iter, md_iter;
	uint32_t offset_blocks;
	int rc;

	offset_blocks = 0;
	_iov_iter_init(&data_iter, iovs, iovcnt);
	_iov_iter_init(&md_iter, md_iov, 1);

	while (offset_blocks < num_blocks) {
		rc = _dix_verify_split(&data_iter, &md_iter, offset_blocks, ctx, err_blk);
		if (rc != 0) {
			return rc;
		}
		offset_blocks++;
	}

	return 0;
}

int
spdk_dix_verify(struct iovec *iovs, int iovcnt, struct iovec *md_iov,
		uint32_t num_blocks, const struct spdk_dif_ctx *ctx,
		struct spdk_dif_error *err_blk)
{
	if (!_are_iovs_valid(iovs, iovcnt, ctx->block_size * num_blocks) ||
	    !_are_iovs_valid(md_iov, 1, ctx->md_size * num_blocks)) {
		SPDK_ERRLOG("Size of iovec array is not valid.\n");
		return -EINVAL;
	}

	if (_dif_is_disabled(ctx->dif_type)) {
		return 0;
	}

	if (_are_iovs_bytes_multiple(iovs, iovcnt, ctx->block_size)) {
		return dix_verify(iovs, iovcnt, md_iov, num_blocks, ctx, err_blk);
	} else {
		return dix_verify_split(iovs, iovcnt, md_iov, num_blocks, ctx, err_blk);
	}
}

int
spdk_dix_inject_error(struct iovec *iovs, int iovcnt, struct iovec *md_iov,
		      uint32_t num_blocks, const struct spdk_dif_ctx *ctx,
		      uint32_t inject_flags, uint32_t *inject_offset)
{
	int rc;

	if (!_are_iovs_valid(iovs, iovcnt, ctx->block_size * num_blocks) ||
	    !_are_iovs_valid(md_iov, 1, ctx->md_size * num_blocks)) {
		SPDK_ERRLOG("Size of iovec array is not valid.\n");
		return -EINVAL;
	}

	if (inject_flags & SPDK_DIF_REFTAG_ERROR) {
		rc = dif_inject_error(md_iov, 1, ctx->md_size, num_blocks,
				      ctx->guard_interval + offsetof(struct spdk_dif, ref_tag),
				      _member_size(struct spdk_dif, ref_tag),
				      inject_offset);
		if (rc != 0) {
			SPDK_ERRLOG("Failed to inject error to Reference Tag.\n");
			return rc;
		}
	}

	if (inject_flags & SPDK_DIF_APPTAG_ERROR) {
		rc = dif_inject_error(md_iov, 1, ctx->md_size, num_blocks,
				      ctx->guard_interval + offsetof(struct spdk_dif, app_tag),
				      _member_size(struct spdk_dif, app_tag),
				      inject_offset);
		if (rc != 0) {
			SPDK_ERRLOG("Failed to inject error to Application Tag.\n");
			return rc;
		}
	}

	if (inject_flags & SPDK_DIF_GUARD_ERROR) {
		rc = dif_inject_error(md_iov, 1, ctx->md_size, num_blocks,
				      ctx->guard_interval,
				      _member_size(struct spdk_dif, guard),
				      inject_offset);
		if (rc != 0) {
			SPDK_ERRLOG("Failed to inject error to Guard.\n");
			return rc;
		}
	}

	if (inject_flags & SPDK_DIF_DATA_ERROR) {
		/* Note: Error injection to data block is expected to be detected
		 * as guard error.
		 */
		rc = dif_inject_error(iovs, iovcnt, ctx->block_size, num_blocks,
				      0,
				      ctx->block_size,
				      inject_offset);
		if (rc != 0) {
			SPDK_ERRLOG("Failed to inject error to Guard.\n");
			return rc;
		}
	}

	return 0;
}