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From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Theodore Ts'o <tytso@mit.edu>,
	Omar Sandoval <osandov@fb.com>, Sagi Grimberg <sagi@grimberg.me>,
	Dave Chinner <dchinner@redhat.com>,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Mike Snitzer <snitzer@redhat.com>,
	dm-devel@redhat.com, Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org,
	David Sterba <dsterba@suse.com>,
	linux-btrfs@vger.kernel.org,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	linux-xfs@vger.kernel.org, Gao Xiang <gaoxiang25@huawei.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-ext4@vger.kernel.org, Coly Li <colyli@suse.de>,
	linux-bcache@vger.kernel.org, Boaz Harrosh <ooo@electrozaur.com>,
	Bob Peterson <rpeterso@redhat.com>,
	cluster-devel@redhat.com, Ming Lei <ming.lei@redhat.com>
Subject: [PATCH V14 08/18] block: introduce mp_bvec_last_segment()
Date: Mon, 21 Jan 2019 16:17:55 +0800
Message-ID: <20190121081805.32727-9-ming.lei@redhat.com> (raw)
In-Reply-To: <20190121081805.32727-1-ming.lei@redhat.com>

BTRFS and guard_bio_eod() need to get the last singlepage segment
from one multipage bvec, so introduce this helper to make them happy.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/linux/bvec.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 0ae729b1c9fe..21f76bad7be2 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -131,4 +131,26 @@ static inline bool bvec_iter_advance(const struct bio_vec *bv,
 	.bi_bvec_done	= 0,						\
 }
 
+/*
+ * Get the last single-page segment from the multi-page bvec and store it
+ * in @seg
+ */
+static inline void mp_bvec_last_segment(const struct bio_vec *bvec,
+					struct bio_vec *seg)
+{
+	unsigned total = bvec->bv_offset + bvec->bv_len;
+	unsigned last_page = (total - 1) / PAGE_SIZE;
+
+	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


  parent reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-21  8:17 [PATCH V14 00/18] block: support multi-page bvec Ming Lei
2019-01-21  8:17 ` [PATCH V14 01/18] btrfs: look at bi_size for repair decisions Ming Lei
2019-01-21  8:17 ` [PATCH V14 02/18] block: don't use bio->bi_vcnt to figure out segment number Ming Lei
2019-01-21  8:17 ` [PATCH V14 03/18] block: remove bvec_iter_rewind() Ming Lei
2019-01-21  8:17 ` [PATCH V14 04/18] block: introduce multi-page bvec helpers Ming Lei
2019-01-21  8:17 ` [PATCH V14 05/18] block: introduce bio_for_each_mp_bvec() and rq_for_each_mp_bvec() Ming Lei
2019-01-21  8:17 ` [PATCH V14 06/18] block: use bio_for_each_mp_bvec() to compute multi-page bvec count Ming Lei
2019-01-21  8:17 ` [PATCH V14 07/18] block: use bio_for_each_mp_bvec() to map sg Ming Lei
2019-01-21  8:17 ` Ming Lei [this message]
2019-01-21  8:17 ` [PATCH V14 09/18] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2019-01-21  8:17 ` [PATCH V14 10/18] btrfs: use mp_bvec_last_segment to get bio's last page Ming Lei
2019-01-21  8:17 ` [PATCH V14 11/18] block: loop: pass multi-page bvec to iov_iter Ming Lei
2019-01-21  8:17 ` [PATCH V14 12/18] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages() Ming Lei
2019-01-21  8:18 ` [PATCH V14 13/18] block: allow bio_for_each_segment_all() to iterate over multi-page bvec Ming Lei
2019-01-21  8:18 ` [PATCH V14 14/18] block: enable multipage bvecs Ming Lei
2019-01-21  8:18 ` [PATCH V14 15/18] block: always define BIO_MAX_PAGES as 256 Ming Lei
2019-01-21  8:18 ` [PATCH V14 16/18] block: document usage of bio iterator helpers Ming Lei
2019-01-21  8:18 ` [PATCH V14 17/18] block: kill QUEUE_FLAG_NO_SG_MERGE Ming Lei
2019-01-21  8:18 ` [PATCH V14 18/18] block: kill BLK_MQ_F_SG_MERGE Ming Lei
2019-01-21  8:22 ` [PATCH V14 00/18] block: support multi-page bvec Christoph Hellwig
2019-01-21  8:37   ` Ming Lei
2019-01-21  8:38     ` Christoph Hellwig
2019-01-21  8:40       ` Ming Lei
2019-01-21  9:43 ` Sagi Grimberg
2019-01-22  2:01   ` Ming Lei

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