linux-kernel - [PATCH v1 31/54] block: introduce bio_segments

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Message-Id: <1482854250-13481-32-git-send-email-tom.leiming@gmail.com>
Date:   Tue, 27 Dec 2016 23:56:20 +0800
From:   Ming Lei <tom.leiming@...il.com>
To:     Jens Axboe <axboe@...com>, linux-kernel@...r.kernel.org
Cc:     linux-block@...r.kernel.org, Christoph Hellwig <hch@...radead.org>,
        Ming Lei <tom.leiming@...il.com>,
        Mike Christie <mchristi@...hat.com>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Hannes Reinecke <hare@...e.com>,
        Chaitanya Kulkarni <chaitanya.kulkarni@...t.com>
Subject: [PATCH v1 31/54] block: introduce bio_segments_all()

There are still several direct access to .bi_vcnt, so
introduce this helper to replace that usage for supporting
multipage bvec.

Signed-off-by: Ming Lei <tom.leiming@...il.com>
---
 include/linux/bio.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index efa0b3627735..b0929cf8c7fe 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -391,6 +391,27 @@ static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 		bv->bv_len = iter.bi_bvec_done;
 }
 
+/*
+ * Return how many singlepage bvecs included in this bio,
+ * and this helper is only used for some fs to replace
+ * bio->bi_vcnt.
+ */
+static inline unsigned bio_segments_all(struct bio *bio)
+{
+	unsigned segs = 0;
+	int i;
+	struct bio_vec *bv;
+	struct bvec_iter_all bia;
+
+	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
+
+	bio_for_each_segment_all_sp(bv, bio, i, bia)
+		segs++;
+
+	return segs;
+}
+
+
 enum bip_flags {
 	BIP_BLOCK_INTEGRITY	= 1 << 0, /* block layer owns integrity data */
 	BIP_MAPPED_INTEGRITY	= 1 << 1, /* ref tag has been remapped */
-- 
2.7.4