This patches introduce bio_for_each_segment_all_sp() and bio_for_each_segment_all_mp(). bio_for_each_segment_all_sp() is for replacing bio_for_each_segment_all() in case that the returned bvec has to be single page bvec. bio_for_each_segment_all_mp() is for replacing bio_for_each_segment_all() in case that user wants to update the returned bvec via the pointer. Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> --- include/linux/bio.h | 24 ++++++++++++++++++++++++ include/linux/blk_types.h | 6 ++++++ 2 files changed, 30 insertions(+) diff --git a/include/linux/bio.h b/include/linux/bio.h index bdbc9480229d..a4bb694b4da5 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -216,6 +216,30 @@ static inline void bio_advance_iter_mp(struct bio *bio, struct bvec_iter *iter, #define bio_for_each_segment_mp(bvl, bio, iter) \ __bio_for_each_segment_mp(bvl, bio, iter, (bio)->bi_iter) +/* + * This helper returns each bvec stored in bvec table directly, + * so the returned bvec points to one multipage bvec in the table + * and caller can update the bvec via the returnd pointer. + */ +#define bio_for_each_segment_all_mp(bvl, bio, i) \ + bio_for_each_segment_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 someone need to update bvec in the table, please use + * bio_for_each_segment_all_mp() and make sure it is correctly used + * since the bvec points to one multipage bvec. + */ +#define bio_for_each_segment_all_sp(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_segments(struct bio *bio) diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index e210da6d14b8..3650932f2080 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -118,6 +118,12 @@ struct bio { #define BIO_RESET_BYTES offsetof(struct bio, bi_max_vecs) +/* this iter is only for implementing bio_for_each_segment_rd() */ +struct bvec_iter_all { + struct bvec_iter iter; + struct bio_vec bv; /* in-flight singlepage bvec */ +}; + /* * bio flags */ -- 2.9.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>