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    Subject[PATCH V12 08/20] block: introduce bio_for_each_bvec() and rq_for_each_bvec()
    Date
    bio_for_each_bvec() is used for iterating over multi-page bvec for bio
    split & merge code.

    rq_for_each_bvec() can be used for drivers which may handle the
    multi-page bvec directly, so far loop is one perfect use case.

    Reviewed-by: Omar Sandoval <osandov@fb.com>
    Signed-off-by: Ming Lei <ming.lei@redhat.com>
    ---
    include/linux/bio.h | 10 ++++++++++
    include/linux/blkdev.h | 4 ++++
    include/linux/bvec.h | 7 +++++++
    3 files changed, 21 insertions(+)

    diff --git a/include/linux/bio.h b/include/linux/bio.h
    index 6a0ff02f4d1c..46fd0e03233b 100644
    --- a/include/linux/bio.h
    +++ b/include/linux/bio.h
    @@ -156,6 +156,16 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
    #define bio_for_each_segment(bvl, bio, iter) \
    __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)

    +#define __bio_for_each_bvec(bvl, bio, iter, start) \
    + for (iter = (start); \
    + (iter).bi_size && \
    + ((bvl = bvec_iter_bvec((bio)->bi_io_vec, (iter))), 1); \
    + bio_advance_iter((bio), &(iter), (bvl).bv_len))
    +
    +/* iterate over multi-page bvec */
    +#define bio_for_each_bvec(bvl, bio, iter) \
    + __bio_for_each_bvec(bvl, bio, iter, (bio)->bi_iter)
    +
    #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)

    static inline unsigned bio_segments(struct bio *bio)
    diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
    index 399a7a415609..fa263de3f1d1 100644
    --- a/include/linux/blkdev.h
    +++ b/include/linux/blkdev.h
    @@ -799,6 +799,10 @@ struct req_iterator {
    __rq_for_each_bio(_iter.bio, _rq) \
    bio_for_each_segment(bvl, _iter.bio, _iter.iter)

    +#define rq_for_each_bvec(bvl, _rq, _iter) \
    + __rq_for_each_bio(_iter.bio, _rq) \
    + bio_for_each_bvec(bvl, _iter.bio, _iter.iter)
    +
    #define rq_iter_last(bvec, _iter) \
    (_iter.bio->bi_next == NULL && \
    bio_iter_last(bvec, _iter.iter))
    diff --git a/include/linux/bvec.h b/include/linux/bvec.h
    index babc6316c117..d441486db605 100644
    --- a/include/linux/bvec.h
    +++ b/include/linux/bvec.h
    @@ -65,6 +65,13 @@ struct bvec_iter {
    #define bvec_iter_page_idx(bvec, iter) \
    (bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)

    +#define bvec_iter_bvec(bvec, iter) \
    +((struct bio_vec) { \
    + .bv_page = bvec_iter_page((bvec), (iter)), \
    + .bv_len = bvec_iter_len((bvec), (iter)), \
    + .bv_offset = bvec_iter_offset((bvec), (iter)), \
    +})
    +
    /* For building single-page bvec(segment) in flight */
    #define segment_iter_offset(bvec, iter) \
    (bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
    --
    2.9.5
    \
     
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