From: Ming Lei <ming.lei@redhat.com>
Date: Mon, 18 Dec 2017 20:22:03 +0800
Subject: [PATCH] block: introduce bio helpers for converting to multipage bvec
Git-commit: 86292abc5af206f64192a0b60da06fd604debdc0
Patch-mainline: v4.16-rc1
References: bsc#1104967,FATE#325924

The following helpers are introduced for converting current users of
direct access to bvec table, and prepares for supporting multipage bvec:

	bio_pages_all()
	bio_first_bvec_all()
	bio_first_page_all()
	bio_last_bvec_all()

All are named as bio_*_all() to following bio_for_each_segment_all(),
they can only be used on bio of !bio_flagged(bio, BIO_CLONED), that means
the whole bvec table is covered.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 include/linux/bio.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 82f0c8fd7be8..435ddf04e889 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -300,6 +300,29 @@ static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 		bv->bv_len = iter.bi_bvec_done;
 }
 
+static inline unsigned bio_pages_all(struct bio *bio)
+{
+	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
+	return bio->bi_vcnt;
+}
+
+static inline struct bio_vec *bio_first_bvec_all(struct bio *bio)
+{
+	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
+	return bio->bi_io_vec;
+}
+
+static inline struct page *bio_first_page_all(struct bio *bio)
+{
+	return bio_first_bvec_all(bio)->bv_page;
+}
+
+static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
+{
+	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
+	return &bio->bi_io_vec[bio->bi_vcnt - 1];
+}
+
 enum bip_flags {
 	BIP_BLOCK_INTEGRITY	= 1 << 0, /* block layer owns integrity data */
 	BIP_MAPPED_INTEGRITY	= 1 << 1, /* ref tag has been remapped */
-- 
2.16.4