From f9df1cd99ebd82f05e8f5e0aa7e38cb8d3c791d7 Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Thu, 29 Jun 2017 11:31:14 -0700 Subject: bio: add bvec_iter rewind API Some ->bi_end_io handlers (for example: pi_verify or decrypt handlers) need to know original data vector, but after bio traverse io-stack it may be advanced, splited and relocated many times so it is hard to guess original iterator. Let's add 'bi_done' conter which accounts number of bytes iterator was advanced during it's evolution. Later end_io handler may easily restore original iterator by rewinding iterator to iter->bi_done. Note: this change makes sizeof (struct bvec_iter) multiple to 8 Reviewed-by: Hannes Reinecke Reviewed-by: Christoph Hellwig Signed-off-by: Dmitry Monakhov [hch: switched to true/false return] Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- include/linux/bio.h | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'include/linux/bio.h') diff --git a/include/linux/bio.h b/include/linux/bio.h index d5e8689f86b8..1eba19580185 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -165,14 +165,29 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter, { iter->bi_sector += bytes >> 9; - if (bio_no_advance_iter(bio)) + if (bio_no_advance_iter(bio)) { iter->bi_size -= bytes; - else { + iter->bi_done += bytes; + } else { bvec_iter_advance(bio->bi_io_vec, iter, bytes); /* TODO: It is reasonable to complete bio with error here. */ } } +static inline bool bio_rewind_iter(struct bio *bio, struct bvec_iter *iter, + unsigned int bytes) +{ + iter->bi_sector -= bytes >> 9; + + if (bio_no_advance_iter(bio)) { + iter->bi_size += bytes; + iter->bi_done -= bytes; + return true; + } + + return bvec_iter_rewind(bio->bi_io_vec, iter, bytes); +} + #define __bio_for_each_segment(bvl, bio, iter, start) \ for (iter = (start); \ (iter).bi_size && \ -- cgit v1.2.3-59-g8ed1b