Some drivers often use external bvec table, so introduce
this helper for this case. It is always safe to access the
bio->bi_io_vec in this way for this case.

After converting to this usage, it will becomes a bit easier
to evaluate the remaining direct access to bio->bi_io_vec,
so it can help to prepare for the following multipage bvec
support.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
 block/bio.c                   |  8 ++++++--
 drivers/block/floppy.c        |  3 +--
 drivers/md/bcache/io.c        |  4 +---
 drivers/md/bcache/journal.c   |  4 +---
 drivers/md/bcache/movinggc.c  |  6 ++----
 drivers/md/bcache/request.c   |  2 +-
 drivers/md/bcache/super.c     | 12 +++---------
 drivers/md/bcache/writeback.c |  5 ++---
 drivers/md/dm-bufio.c         |  4 +---
 drivers/md/dm.c               |  2 +-
 drivers/md/multipath.c        |  2 +-
 drivers/md/raid5-cache.c      |  2 +-
 drivers/md/raid5.c            |  9 ++-------
 drivers/nvme/target/io-cmd.c  |  4 +---
 fs/logfs/dev_bdev.c           |  4 +---
 include/linux/bio.h           |  3 ++-
 16 files changed, 27 insertions(+), 47 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 2cf6ebabc68c..de257ced69b1 100644
--- a/block/bio.c
+++ b/block/bio.c

@@ -270,11 +270,15 @@ static void bio_free(struct bio *bio)
 	}
 }
 
-void bio_init(struct bio *bio)
+void bio_init(struct bio *bio, struct bio_vec *table,
+	      unsigned short max_vecs)
 {
 	memset(bio, 0, sizeof(*bio));
 	atomic_set(&bio->__bi_remaining, 1);
 	atomic_set(&bio->__bi_cnt, 1);
+
+	bio->bi_io_vec = table;
+	bio->bi_max_vecs = max_vecs;
 }
 EXPORT_SYMBOL(bio_init);
 

@@ -480,7 +484,7 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
 		return NULL;
 
 	bio = p + front_pad;
-	bio_init(bio);
+	bio_init(bio, NULL, 0);
 
 	if (nr_iovecs > inline_vecs) {
 		unsigned long idx = 0;

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index e3d8e4ced4a2..6a3ff2b2e3ae 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c

@@ -3806,8 +3806,7 @@ static int __floppy_read_block_0(struct block_device *bdev, int drive)
 
 	cbdata.drive = drive;
 
-	bio_init(&bio);
-	bio.bi_io_vec = &bio_vec;
+	bio_init(&bio, &bio_vec, 1);
 	bio_vec.bv_page = page;
 	bio_vec.bv_len = size;
 	bio_vec.bv_offset = 0;

diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c
index e97b0acf7b8d..db45a88c0ce9 100644
--- a/drivers/md/bcache/io.c
+++ b/drivers/md/bcache/io.c

@@ -24,9 +24,7 @@ struct bio *bch_bbio_alloc(struct cache_set *c)
 	struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO);
 	struct bio *bio = &b->bio;
 
-	bio_init(bio);
-	bio->bi_max_vecs	 = bucket_pages(c);
-	bio->bi_io_vec		 = bio->bi_inline_vecs;
+	bio_init(bio, bio->bi_inline_vecs, bucket_pages(c));
 
 	return bio;
 }

diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 6925023e12d4..1198e53d5670 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c

@@ -448,13 +448,11 @@ static void do_journal_discard(struct cache *ca)
 
 		atomic_set(&ja->discard_in_flight, DISCARD_IN_FLIGHT);
 
-		bio_init(bio);
+		bio_init(bio, bio->bi_inline_vecs, 1);
 		bio_set_op_attrs(bio, REQ_OP_DISCARD, 0);
 		bio->bi_iter.bi_sector	= bucket_to_sector(ca->set,
 						ca->sb.d[ja->discard_idx]);
 		bio->bi_bdev		= ca->bdev;
-		bio->bi_max_vecs	= 1;
-		bio->bi_io_vec		= bio->bi_inline_vecs;
 		bio->bi_iter.bi_size	= bucket_bytes(ca);
 		bio->bi_end_io		= journal_discard_endio;
 

diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index 5c4bddecfaf0..13b8a907006d 100644
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c

@@ -77,15 +77,13 @@ static void moving_init(struct moving_io *io)
 {
 	struct bio *bio = &io->bio.bio;
 
-	bio_init(bio);
+	bio_init(bio, bio->bi_inline_vecs,
+		 DIV_ROUND_UP(KEY_SIZE(&io->w->key), PAGE_SECTORS));
 	bio_get(bio);
 	bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
 
 	bio->bi_iter.bi_size	= KEY_SIZE(&io->w->key) << 9;
-	bio->bi_max_vecs	= DIV_ROUND_UP(KEY_SIZE(&io->w->key),
-					       PAGE_SECTORS);
 	bio->bi_private		= &io->cl;
-	bio->bi_io_vec		= bio->bi_inline_vecs;
 	bch_bio_map(bio, NULL);
 }
 

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 0d99b5f4b3e6..f49c5417527d 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c

@@ -623,7 +623,7 @@ static void do_bio_hook(struct search *s, struct bio *orig_bio)
 {
 	struct bio *bio = &s->bio.bio;
 
-	bio_init(bio);
+	bio_init(bio, NULL, 0);
 	__bio_clone_fast(bio, orig_bio);