| Message ID | 1455519687-23873-2-git-send-email-ming.lei@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> +/* > + * bio_get_last_bvec() is introduced to get the last bvec of one > + * bio for bio_will_gap(). > + * > + * TODO: make it more efficient. > + */ > +static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv) > +{ > + struct bvec_iter iter; > + > + bio_for_each_segment(*bv, bio, iter) > + if (bv->bv_len == iter.bi_size) > + break; > +} This helper is used for each req/bio once or more. I'd say it's critical to make it efficient and not settle for a quick bail for drivers that don't have a virt_boundary like you did in patch #2. However, given that it's a regression bug fix I'm not sure it's the best idea to add logic here. -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/bio.h b/include/linux/bio.h index 5349e68..56d2db8 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -265,6 +265,26 @@ static inline unsigned bio_segments(struct bio *bio) return segs; } +static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv) +{ + *bv = bio_iovec(bio); +} + +/* + * bio_get_last_bvec() is introduced to get the last bvec of one + * bio for bio_will_gap(). + * + * TODO: make it more efficient. + */ +static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv) +{ + struct bvec_iter iter; + + bio_for_each_segment(*bv, bio, iter) + if (bv->bv_len == iter.bi_size) + break; +} + /* * get a reference to a bio, so it won't disappear. the intended use is * something like:
After bio splitting is introduced, the splitted bio can be fast-cloned, which is correct because biovecs has become immutable since v3.13. Unfortunately bio_will_gap() isn't ready for this kind of change, because it figures out the last bvec via 'bi_io_vec[prev->bi_vcnt - 1]'. This patch introduces two helpers for getting the first and last bvec of one bio. Cc: stable@vger.kernel.org # v4.3+ Reported-by: Sagi Grimberg <sagig@dev.mellanox.co.il> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Ming Lei <ming.lei@canonical.com> --- include/linux/bio.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)