On Tue, Feb 28, 2017 at 11:41:39PM +0800, Ming Lei wrote:
> Use this helper, instead of direct access to .bi_vcnt.
what We really need to do for the behind IO is:
- allocate memory and copy bio data to the memory
- let behind bio do IO against the memory
The behind bio doesn't need to have the exactly same bio_vec setting. If we
just track the new memory, we don't need use the bio_segments_all and access
bio_vec too.
Thanks,
Shaohua
> Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
> ---
> drivers/md/raid1.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 316bd6dd6cc1..7396c99ff7b1 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -1091,7 +1091,8 @@ static void alloc_behind_pages(struct bio *bio, struct r1bio *r1_bio)
> {
> int i;
> struct bio_vec *bvec;
> - struct bio_vec *bvecs = kzalloc(bio->bi_vcnt * sizeof(struct bio_vec),
> + unsigned vcnt = bio_segments_all(bio);
> + struct bio_vec *bvecs = kzalloc(vcnt * sizeof(struct bio_vec),
> GFP_NOIO);
> if (unlikely(!bvecs))
> return;
> @@ -1107,12 +1108,12 @@ static void alloc_behind_pages(struct bio *bio, struct r1bio *r1_bio)
> kunmap(bvec->bv_page);
> }
> r1_bio->behind_bvecs = bvecs;
> - r1_bio->behind_page_count = bio->bi_vcnt;
> + r1_bio->behind_page_count = vcnt;
> set_bit(R1BIO_BehindIO, &r1_bio->state);
> return;
>
> do_sync_io:
> - for (i = 0; i < bio->bi_vcnt; i++)
> + for (i = 0; i < vcnt; i++)
> if (bvecs[i].bv_page)
> put_page(bvecs[i].bv_page);
> kfree(bvecs);
> --
> 2.7.4
>
