[dm-devel] [PATCH 1/4] dm: fix clone_bio() to trigger blk_recount_segments()

[Ming Lei]

On Sat, Jan 19, 2019 at 01:05:03PM -0500, Mike Snitzer wrote:
> DM's clone_bio() now benefits from using bio_trim() by fixing the fact
> that clone_bio() wasn't clearing BIO_SEG_VALID like bio_trim() does;
> which triggers blk_recount_segments() via bio_phys_segments().
> 
> Signed-off-by: Mike Snitzer <snitzer at redhat.com>
> ---
>  drivers/md/dm.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index d67c95ef8d7e..fcb97b0a5743 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1320,7 +1320,7 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio,
>  
>  	__bio_clone_fast(clone, bio);
>  
> -	if (unlikely(bio_integrity(bio) != NULL)) {
> +	if (bio_integrity(bio)) {
>  		int r;
>  
>  		if (unlikely(!dm_target_has_integrity(tio->ti->type) &&
> @@ -1336,11 +1336,7 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio,
>  			return r;
>  	}
>  
> -	bio_advance(clone, to_bytes(sector - clone->bi_iter.bi_sector));
> -	clone->bi_iter.bi_size = to_bytes(len);
> -
> -	if (unlikely(bio_integrity(bio) != NULL))
> -		bio_integrity_trim(clone);
> +	bio_trim(clone, sector - clone->bi_iter.bi_sector, len);
>  
>  	return 0;
>  }
> -- 
> 2.15.0
> 

Reviewed-by: Ming Lei <ming.lei at redhat.com>

Thanks,
Ming