blk-integrity.c

// SPDX-License-Identifier: GPL-2.0
/*
 * blk-integrity.c - Block layer data integrity extensions
 *
 * Copyright (C) 2007, 2008 Oracle Corporation
 * Written by: Martin K. Petersen <martin.petersen@oracle.com>
 */

#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/mempool.h>
#include <linux/bio.h>
#include <linux/scatterlist.h>
#include <linux/export.h>
#include <linux/slab.h>

#include "blk.h"

/**
 * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements
 * @q:		request queue
 * @bio:	bio with integrity metadata attached
 *
 * Description: Returns the number of elements required in a
 * scatterlist corresponding to the integrity metadata in a bio.
 */
int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)
{
	struct bio_vec iv, ivprv = { NULL };
	unsigned int segments = 0;
	unsigned int seg_size = 0;
	struct bvec_iter iter;
	int prev = 0;

	bio_for_each_integrity_vec(iv, bio, iter) {

		if (prev) {
			if (!biovec_phys_mergeable(q, &ivprv, &iv))
				goto new_segment;
			if (seg_size + iv.bv_len > queue_max_segment_size(q))
				goto new_segment;

			seg_size += iv.bv_len;
		} else {
new_segment:
			segments++;
			seg_size = iv.bv_len;
		}

		prev = 1;
		ivprv = iv;
	}

	return segments;
}
EXPORT_SYMBOL(blk_rq_count_integrity_sg);

/**
 * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
 * @q:		request queue
 * @bio:	bio with integrity metadata attached
 * @sglist:	target scatterlist
 *
 * Description: Map the integrity vectors in request into a
 * scatterlist.  The scatterlist must be big enough to hold all
 * elements.  I.e. sized using blk_rq_count_integrity_sg().
 */
int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
			    struct scatterlist *sglist)
{