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    SubjectRe: [PATCH V12 14/20] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages()
    On Mon, Nov 26, 2018 at 10:17:14AM +0800, Ming Lei wrote:
    > bch_bio_alloc_pages() is always called on one new bio, so it is safe
    > to access the bvec table directly. Given it is the only kind of this
    > case, open code the bvec table access since bio_for_each_segment_all()
    > will be changed to support for iterating over multipage bvec.
    >
    > Acked-by: Coly Li <colyli@suse.de>
    > Reviewed-by: Christoph Hellwig <hch@lst.de>

    Reviewed-by: Omar Sandoval <osandov@fb.com>

    > Signed-off-by: Ming Lei <ming.lei@redhat.com>
    > ---
    > drivers/md/bcache/util.c | 6 +++++-
    > 1 file changed, 5 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c
    > index 20eddeac1531..62fb917f7a4f 100644
    > --- a/drivers/md/bcache/util.c
    > +++ b/drivers/md/bcache/util.c
    > @@ -270,7 +270,11 @@ int bch_bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
    > int i;
    > struct bio_vec *bv;
    >
    > - bio_for_each_segment_all(bv, bio, i) {
    > + /*
    > + * This is called on freshly new bio, so it is safe to access the
    > + * bvec table directly.
    > + */
    > + for (i = 0, bv = bio->bi_io_vec; i < bio->bi_vcnt; bv++, i++) {
    > bv->bv_page = alloc_page(gfp_mask);
    > if (!bv->bv_page) {
    > while (--bv >= bio->bi_io_vec)
    > --
    > 2.9.5
    >

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