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    Subject[RESEND PATCH V5 17/33] block: bio: introduce bio_for_each_page_all2 and bio_for_each_segment_all
    Date
    This patch introduces bio_for_each_page_all2(), which is for replacing
    bio_for_each_page_all() in case that the returned bvec has to be single
    page bvec.

    Given the interface type has to be changed for passing one local iterator
    variable of 'bvec_iter_all', and doing all changes in one single patch
    isn't realistic, so use the name of bio_for_each_page_all2() temporarily
    for conversion, and once all bio_for_each_page_all() is converted, the
    original name of bio_for_each_page_all() will be recovered finally.

    This patch introduce bio_for_each_segment_all too, which is used for
    updating bvec table directly, and users should be carful about this
    helper since it returns real multipage segment now.

    Signed-off-by: Ming Lei <ming.lei@redhat.com>
    ---
    include/linux/bio.h | 18 ++++++++++++++++++
    include/linux/bvec.h | 6 ++++++
    2 files changed, 24 insertions(+)

    diff --git a/include/linux/bio.h b/include/linux/bio.h
    index 61a04c131641..75baad77d9a8 100644
    --- a/include/linux/bio.h
    +++ b/include/linux/bio.h
    @@ -225,6 +225,24 @@ static inline bool bio_rewind_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_segment_all(bvl, bio, i) \
    + bio_for_each_page_all((bvl), (bio), (i))
    +
    +/*
    + * This helper returns singlepage bvec to caller, and the sp bvec is
    + * generated in-flight from multipage bvec stored in bvec table. So we
    + * can _not_ change the bvec stored in bio->bi_io_vec[] via this helper.
    + *
    + * If bvec need to be updated in the table, please use
    + * bio_for_each_segment_all() and make sure it is correctly used since
    + * bvec may points to one multipage bvec.
    + */
    +#define bio_for_each_page_all2(bvl, bio, i, bi) \
    + for ((bi).iter = BVEC_ITER_ALL_INIT, i = 0, bvl = &(bi).bv; \
    + (bi).iter.bi_idx < (bio)->bi_vcnt && \
    + (((bi).bv = bio_iter_iovec((bio), (bi).iter)), 1); \
    + bio_advance_iter((bio), &(bi).iter, (bi).bv.bv_len), i++)
    +
    #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)

    static inline unsigned __bio_elements(struct bio *bio, bool seg)
    diff --git a/include/linux/bvec.h b/include/linux/bvec.h
    index 217afcd83a15..2deee87b823e 100644
    --- a/include/linux/bvec.h
    +++ b/include/linux/bvec.h
    @@ -84,6 +84,12 @@ struct bvec_iter {
    current bvec */
    };

    +/* this iter is only for implementing bio_for_each_page_all2() */
    +struct bvec_iter_all {
    + struct bvec_iter iter;
    + struct bio_vec bv; /* in-flight singlepage bvec */
    +};
    +
    /*
    * various member access, note that bio_data should of course not be used
    * on highmem page vectors
    --
    2.9.5
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