From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Dmitry Monakhov To: fstests@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, Dmitry Monakhov Subject: [PATCH 8/9] bio: add bvec_iter rewind API Date: Wed, 10 May 2017 19:20:51 +0400 Message-Id: <1494429652-9488-9-git-send-email-dmonakhov@openvz.org> In-Reply-To: <1494429652-9488-1-git-send-email-dmonakhov@openvz.org> References: <1494429652-9488-1-git-send-email-dmonakhov@openvz.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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 --- include/linux/bio.h | 21 +++++++++++++++++++-- include/linux/bvec.h | 27 +++++++++++++++++++++++++++ 2 files changed, 46 insertions(+), 2 deletions(-) diff --git a/include/linux/bio.h b/include/linux/bio.h index 643ecba..ab812a0 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -166,9 +166,10 @@ 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 { int err; err = bvec_iter_advance(bio->bi_io_vec, iter, bytes); @@ -176,6 +177,22 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter, } } +static inline int bio_rewind_iter(struct bio *bio, struct bvec_iter *iter, + unsigned int bytes) +{ + int err = 0; + + iter->bi_sector -= bytes >> 9; + + if (bio_no_advance_iter(bio)) { + iter->bi_size += bytes; + iter->bi_done -= bytes; + } else { + err = bvec_iter_rewind(bio->bi_io_vec, iter, bytes); + } + return err; +} + #define __bio_for_each_segment(bvl, bio, iter, start) \ for (iter = (start); \ (iter).bi_size && \ diff --git a/include/linux/bvec.h b/include/linux/bvec.h index 984a7a8..8cfe4d6 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -40,6 +40,8 @@ struct bvec_iter { unsigned int bi_idx; /* current index into bvl_vec */ + unsigned int bi_done; /* number of bytes completed */ + unsigned int bi_bvec_done; /* number of bytes completed in current bvec */ }; @@ -84,6 +86,7 @@ static inline int bvec_iter_advance(const struct bio_vec *bv, bytes -= len; iter->bi_size -= len; iter->bi_bvec_done += len; + iter->bi_done += len; if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) { iter->bi_bvec_done = 0; @@ -93,6 +96,30 @@ static inline int bvec_iter_advance(const struct bio_vec *bv, return 0; } +static inline int bvec_iter_rewind(const struct bio_vec *bv, + struct bvec_iter *iter, + unsigned int bytes) +{ + while (bytes) { + unsigned len = min(bytes, iter->bi_bvec_done); + + if (iter->bi_bvec_done == 0) { + if (WARN_ONCE(iter->bi_idx == 0, + "Attempted to rewind iter beyond " + "bvec's boundaries\n")) { + return -EINVAL; + } + iter->bi_idx--; + iter->bi_bvec_done = __bvec_iter_bvec(bv, *iter)->bv_len; + continue; + } + bytes -= len; + iter->bi_size += len; + iter->bi_bvec_done -= len; + } + return 0; +} + #define for_each_bvec(bvl, bio_vec, iter, start) \ for (iter = (start); \ (iter).bi_size && \ -- 2.9.3