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block: Find bio sector offset given idx and offset

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

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Martin K. Petersen 2008-10-01 22:42:53 -04:00 committed by Jens Axboe
parent b02739b01c
commit ad3316bf4e
2 changed files with 37 additions and 0 deletions
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36
fs/bio.c
View File

@ -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.

1
include/linux/bio.h
View File

@ -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;