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Commit ad3316bf authored by Martin K. Petersen's avatar Martin K. Petersen Committed by Jens Axboe
Browse files

block: Find bio sector offset given idx and offset 



Helper function to find the sector offset in a bio given bvec index
and page offset.

Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent b02739b0

fs/bio.c

+36 −0
Original line number Diff line number Diff line
@@ -1300,6 +1300,42 @@ struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, int first_sectors) 
	return bp;

}



/**

 *      bio_sector_offset - Find hardware sector offset in bio

 *      @bio:           bio to inspect

 *      @index:         bio_vec index

 *      @offset:        offset in bv_page

 *

 *      Return the number of hardware sectors between beginning of bio

 *      and an end point indicated by a bio_vec index and an offset

 *      within that vector's page.

 */

sector_t bio_sector_offset(struct bio *bio, unsigned short index,

			   unsigned int offset)

{

	unsigned int sector_sz = queue_hardsect_size(bio->bi_bdev->bd_disk->queue);

	struct bio_vec *bv;

	sector_t sectors;

	int i;



	sectors = 0;



	if (index >= bio->bi_idx)

		index = bio->bi_vcnt - 1;



	__bio_for_each_segment(bv, bio, i, 0) {

		if (i == index) {

			if (offset > bv->bv_offset)

				sectors += (offset - bv->bv_offset) / sector_sz;

			break;

		}



		sectors += bv->bv_len / sector_sz;

	}



	return sectors;

}

EXPORT_SYMBOL(bio_sector_offset);



/*

 * create memory pools for biovec's in a bio_set.

include/linux/bio.h

+1 −0
Original line number Diff line number Diff line
@@ -327,6 +327,7 @@ extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int); 
extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,

			   unsigned int, unsigned int);

extern int bio_get_nr_vecs(struct block_device *);

extern sector_t bio_sector_offset(struct bio *, unsigned short, unsigned int);

extern struct bio *bio_map_user(struct request_queue *, struct block_device *,

				unsigned long, unsigned int, int, gfp_t);

struct sg_iovec;