[PATCH 01/10] block: introduce bio helpers for converting to multipage bvec

[Ming Lei <ming.lei@redhat.com>]

These helpers are introduced for converting current users of direct
access to bvec table, and prepares for supporting multipage bvec.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/linux/bio.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 82f0c8fd7be8..3f314e17364a 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -300,6 +300,30 @@ 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_nr_pages(struct bio *bio)
+{
+	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
+
+	return bio->bi_vcnt;
+}
+
+static inline struct bio_vec *bio_first_bvec(struct bio *bio)
+{
+	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
+	return bio->bi_io_vec;
+}
+
+static inline struct page *bio_first_page(struct bio *bio)
+{
+	return bio_first_bvec(bio)->bv_page;
+}
+
+static inline struct bio_vec *bio_last_bvec(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 */
-- 
2.9.5