[PATCH 3/5] buffer_head: separate out create_bh_bio() from submit_bh_wbc()

[Tejun Heo <tj@kernel.org>]

submit_bh_wbc() creates a bio matching the specific @bh and submits it
at the end.  This patch separates out the bio creation part to its own
function, create_bh_bio(), and reimplement submit_bh[_wbc]() using the
function.

As bio can now be manipulated before submitted, we can move out @wbc
handling into submit_bh_wbc() and similarly this will make adding more
submit_bh variants straight-forward.

This patch is pure refactoring and doesn't cause any functional
changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Jan Kara <jack@suse.cz>
---
 fs/buffer.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 170df85..b4b2169 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3086,8 +3086,8 @@ void guard_bio_eod(int op, struct bio *bio)
 	}
 }
 
-static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
-			 enum rw_hint write_hint, struct writeback_control *wbc)
+struct bio *create_bh_bio(int op, int op_flags, struct buffer_head *bh,
+                          enum rw_hint write_hint)
 {
 	struct bio *bio;
 
@@ -3109,11 +3109,6 @@ static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
 	 */
 	bio = bio_alloc(GFP_NOIO, 1);
 
-	if (wbc) {
-		wbc_init_bio(wbc, bio);
-		wbc_account_io(wbc, bh->b_page, bh->b_size);
-	}
-
 	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 	bio_set_dev(bio, bh->b_bdev);
 	bio->bi_write_hint = write_hint;
@@ -3133,13 +3128,32 @@ static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
 		op_flags |= REQ_PRIO;
 	bio_set_op_attrs(bio, op, op_flags);
 
+	return bio;
+}
+
+static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
+			 enum rw_hint write_hint, struct writeback_control *wbc)
+{
+	struct bio *bio;
+
+	bio = create_bh_bio(op, op_flags, bh, write_hint);
+
+	if (wbc) {
+		wbc_init_bio(wbc, bio);
+		wbc_account_io(wbc, bh->b_page, bh->b_size);
+	}
+
 	submit_bio(bio);
 	return 0;
 }
 
 int submit_bh(int op, int op_flags, struct buffer_head *bh)
 {
-	return submit_bh_wbc(op, op_flags, bh, 0, NULL);
+	struct bio *bio;
+
+	bio = create_bh_bio(op, op_flags, bh, 0);
+	submit_bio(bio);
+	return 0;
 }
 EXPORT_SYMBOL(submit_bh);
 
-- 
2.9.5