[PATCH V10 09/19] block: introduce bio_bvecs()

[Ming Lei]

There are still cases in which we need to use bio_bvecs() for get the
number of multi-page segment, so introduce it.

Cc: Dave Chinner <dchinner at redhat.com>
Cc: Kent Overstreet <kent.overstreet at gmail.com>
Cc: Mike Snitzer <snitzer at redhat.com>
Cc: dm-devel at redhat.com
Cc: Alexander Viro <viro at zeniv.linux.org.uk>
Cc: linux-fsdevel at vger.kernel.org
Cc: Shaohua Li <shli at kernel.org>
Cc: linux-raid at vger.kernel.org
Cc: linux-erofs at lists.ozlabs.org
Cc: David Sterba <dsterba at suse.com>
Cc: linux-btrfs at vger.kernel.org
Cc: Darrick J. Wong <darrick.wong at oracle.com>
Cc: linux-xfs at vger.kernel.org
Cc: Gao Xiang <gaoxiang25 at huawei.com>
Cc: Christoph Hellwig <hch at lst.de>
Cc: Theodore Ts'o <tytso at mit.edu>
Cc: linux-ext4 at vger.kernel.org
Cc: Coly Li <colyli at suse.de>
Cc: linux-bcache at vger.kernel.org
Cc: Boaz Harrosh <ooo at electrozaur.com>
Cc: Bob Peterson <rpeterso at redhat.com>
Cc: cluster-devel at redhat.com
Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
 include/linux/bio.h | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 1f0dcf109841..3496c816946e 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -196,7 +196,6 @@ static inline unsigned bio_segments(struct bio *bio)
 	 * We special case discard/write same/write zeroes, because they
 	 * interpret bi_size differently:
 	 */
-
 	switch (bio_op(bio)) {
 	case REQ_OP_DISCARD:
 	case REQ_OP_SECURE_ERASE:
@@ -205,13 +204,34 @@ static inline unsigned bio_segments(struct bio *bio)
 	case REQ_OP_WRITE_SAME:
 		return 1;
 	default:
-		break;
+		bio_for_each_segment(bv, bio, iter)
+			segs++;
+		return segs;
 	}
+}
 
-	bio_for_each_segment(bv, bio, iter)
-		segs++;
+static inline unsigned bio_bvecs(struct bio *bio)
+{
+	unsigned bvecs = 0;
+	struct bio_vec bv;
+	struct bvec_iter iter;
 
-	return segs;
+	/*
+	 * We special case discard/write same/write zeroes, because they
+	 * interpret bi_size differently:
+	 */
+	switch (bio_op(bio)) {
+	case REQ_OP_DISCARD:
+	case REQ_OP_SECURE_ERASE:
+	case REQ_OP_WRITE_ZEROES:
+		return 0;
+	case REQ_OP_WRITE_SAME:
+		return 1;
+	default:
+		bio_for_each_bvec(bv, bio, iter)
+			bvecs++;
+		return bvecs;
+	}
 }
 
 /*
-- 
2.9.5