From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f200.google.com (mail-qt0-f200.google.com [209.85.216.200]) by kanga.kvack.org (Postfix) with ESMTP id 8989B6B029A for ; Thu, 24 May 2018 23:48:26 -0400 (EDT) Received: by mail-qt0-f200.google.com with SMTP id x2-v6so2830343qto.10 for ; Thu, 24 May 2018 20:48:26 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id n12-v6si5817090qkl.306.2018.05.24.20.48.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 24 May 2018 20:48:25 -0700 (PDT) From: Ming Lei Subject: [RESEND PATCH V5 08/33] block: introduce segment_last_page() Date: Fri, 25 May 2018 11:45:56 +0800 Message-Id: <20180525034621.31147-9-ming.lei@redhat.com> In-Reply-To: <20180525034621.31147-1-ming.lei@redhat.com> References: <20180525034621.31147-1-ming.lei@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jens Axboe , Christoph Hellwig , Alexander Viro , Kent Overstreet Cc: David Sterba , Huang Ying , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Theodore Ts'o , "Darrick J . Wong" , Coly Li , Filipe Manana , Ming Lei BTRFS and guard_bio_eod() need to get the last page from one segment, so introduce this helper to make them happy. Signed-off-by: Ming Lei --- include/linux/bvec.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/include/linux/bvec.h b/include/linux/bvec.h index 84c395feed49..217afcd83a15 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -219,4 +219,26 @@ static inline bool bvec_iter_seg_advance(const struct bio_vec *bv, .bi_bvec_done = 0, \ } +/* get the last page from the multipage bvec and store it in @pg */ +static inline void segment_last_page(const struct bio_vec *seg, + struct bio_vec *pg) +{ + unsigned total = seg->bv_offset + seg->bv_len; + unsigned last_page = total / PAGE_SIZE; + + if (last_page * PAGE_SIZE == total) + last_page--; + + pg->bv_page = nth_page(seg->bv_page, last_page); + + /* the whole segment is inside the last page */ + if (seg->bv_offset >= last_page * PAGE_SIZE) { + pg->bv_offset = seg->bv_offset % PAGE_SIZE; + pg->bv_len = seg->bv_len; + } else { + pg->bv_offset = 0; + pg->bv_len = total - last_page * PAGE_SIZE; + } +} + #endif /* __LINUX_BVEC_ITER_H */ -- 2.9.5