[PATCH v2 6/7] fs: make _submit_bh consistent with generic bio chaining

[Dongsu Park]

From: Kent Overstreet <kmo@xxxxxxxxxxxxx>

Make _submit_bh() handle refcounting by increasing bio->bi_remaining,
followed by bio_endio(). Since bio chaining was introduced with
196d38bccfcf ("block: Generic bio chaining"), refcounting should be
done on bi_remaining instead of ancient bio_cnt. Doing that, calling
convention can be consistent with the immutable biovecs API.

Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Signed-off-by: Kent Overstreet <kmo@xxxxxxxxxxxxx>
[dpark: add more description in commit message]
Signed-off-by: Dongsu Park <dongsu.park@xxxxxxxxxxxxxxxx>
---
 fs/buffer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 20805db..dbe5699 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3041,13 +3041,13 @@ int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags)
 	if (buffer_prio(bh))
 		rw |= REQ_PRIO;
 
-	bio_get(bio);
+	atomic_inc(&bio->bi_remaining);
 	submit_bio(rw, bio);
 
 	if (bio_flagged(bio, BIO_EOPNOTSUPP))
 		ret = -EOPNOTSUPP;
 
-	bio_put(bio);
+	bio_endio(bio, 0);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(_submit_bh);
-- 
2.1.0

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