Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755545AbdDDS5C (ORCPT ); Tue, 4 Apr 2017 14:57:02 -0400 Received: from mail-lf0-f66.google.com ([209.85.215.66]:35077 "EHLO mail-lf0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755440AbdDDS46 (ORCPT ); Tue, 4 Apr 2017 14:56:58 -0400 From: Dmitry Monakhov To: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, martin.petersen@oracle.com Cc: Dmitry Monakhov Subject: [PATCH 8/9] bio: add bvec_iter rewind API Date: Tue, 4 Apr 2017 22:56:40 +0400 Message-Id: <1491332201-26926-9-git-send-email-dmonakhov@openvz.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1491332201-26926-1-git-send-email-dmonakhov@openvz.org> References: <1491332201-26926-1-git-send-email-dmonakhov@openvz.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3286 Lines: 108 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 Signed-off-by: Dmitry Monakhov --- include/linux/bio.h | 21 +++++++++++++++++++-- include/linux/bvec.h | 26 ++++++++++++++++++++++++++ 2 files changed, 45 insertions(+), 2 deletions(-) diff --git a/include/linux/bio.h b/include/linux/bio.h index 12b7fcd..491fb0c 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); if (unlikely(err)) @@ -176,6 +177,22 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter, } } +static inline void bio_rewind_iter(struct bio *bio, struct bvec_iter *iter, + unsigned bytes) +{ + iter->bi_sector -= bytes >> 9; + + if (bio_no_advance_iter(bio)) { + iter->bi_size += bytes; + iter->bi_done -= bytes; + } else { + int err; + err = bvec_iter_rewind(bio->bi_io_vec, iter, bytes); + if (unlikely(err)) + bio->bi_error = 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..35cb97b 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 +96,29 @@ 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 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