From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Date: Thu, 15 Nov 2018 16:52:52 +0800 Subject: [Cluster-devel] [PATCH V10 05/19] block: introduce bvec_last_segment() In-Reply-To: <20181115085306.9910-1-ming.lei@redhat.com> References: <20181115085306.9910-1-ming.lei@redhat.com> Message-ID: <20181115085306.9910-6-ming.lei@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit BTRFS and guard_bio_eod() need to get the last singlepage segment from one multipage bvec, so introduce this helper to make them happy. Cc: Dave Chinner Cc: Kent Overstreet Cc: Mike Snitzer Cc: dm-devel at redhat.com Cc: Alexander Viro Cc: linux-fsdevel at vger.kernel.org Cc: Shaohua Li Cc: linux-raid at vger.kernel.org Cc: linux-erofs at lists.ozlabs.org Cc: David Sterba Cc: linux-btrfs at vger.kernel.org Cc: Darrick J. Wong Cc: linux-xfs at vger.kernel.org Cc: Gao Xiang Cc: Christoph Hellwig Cc: Theodore Ts'o Cc: linux-ext4 at vger.kernel.org Cc: Coly Li Cc: linux-bcache at vger.kernel.org Cc: Boaz Harrosh Cc: Bob Peterson Cc: cluster-devel at redhat.com Signed-off-by: Ming Lei --- include/linux/bvec.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/linux/bvec.h b/include/linux/bvec.h index 3d61352cd8cf..01616a0b6220 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -216,4 +216,29 @@ static inline bool mp_bvec_iter_advance(const struct bio_vec *bv, .bi_bvec_done = 0, \ } +/* + * Get the last singlepage segment from the multipage bvec and store it + * in @seg + */ +static inline void bvec_last_segment(const struct bio_vec *bvec, + struct bio_vec *seg) +{ + unsigned total = bvec->bv_offset + bvec->bv_len; + unsigned last_page = total / PAGE_SIZE; + + if (last_page * PAGE_SIZE == total) + last_page--; + + seg->bv_page = nth_page(bvec->bv_page, last_page); + + /* the whole segment is inside the last page */ + if (bvec->bv_offset >= last_page * PAGE_SIZE) { + seg->bv_offset = bvec->bv_offset % PAGE_SIZE; + seg->bv_len = bvec->bv_len; + } else { + seg->bv_offset = 0; + seg->bv_len = total - last_page * PAGE_SIZE; + } +} + #endif /* __LINUX_BVEC_ITER_H */ -- 2.9.5