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 <[email protected]> > --- > 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 >
