Don't decrement bi_size in bio_endio

The only caller of bio_endio that does not pass the full bi_size
is end_that_request_first.  Also, no ->bi_end_io method is really
interested in bi_size being decremented.

So move the decrement and related code into ll_rw_blk and merge it
with order_bio_endio to form req_bio_endio which does endio functionality
specific to request completion.

As some ->bi_end_io methods do check bi_size of 0, we set it thus for
now, but that will go in the next patch.

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
 ./block/ll_rw_blk.c |   42 +++++++++++++++++++++++++++---------------
 ./fs/bio.c          |   23 +++++++++++------------
 2 files changed, 38 insertions(+), 27 deletions(-)

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 27 insertions, 15 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index dfe0948ec8b2..b55ed0df33f0 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -527,22 +527,36 @@ int blk_do_ordered(struct request_queue *q, struct request **rqp)
 	return 1;
 }
 
-static int ordered_bio_endio(struct request *rq, struct bio *bio,
-			     unsigned int nbytes, int error)
+static void req_bio_endio(struct request *rq, struct bio *bio,
+			  unsigned int nbytes, int error)
 {
 	struct request_queue *q = rq->q;
 
-	if (&q->bar_rq != rq)
-		return 0;
+	if (&q->bar_rq != rq) {
+		if (error)
+			clear_bit(BIO_UPTODATE, &bio->bi_flags);
+		else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+			error = -EIO;
 
-	/*
-	 * Okay, this is the barrier request in progress, just
-	 * record the error;
-	 */
-	if (error && !q->orderr)
-		q->orderr = error;
+		if (unlikely(nbytes > bio->bi_size)) {
+			printk("%s: want %u bytes done, only %u left\n",
+			       __FUNCTION__, nbytes, bio->bi_size);
+			nbytes = bio->bi_size;
+		}
 
-	return 1;
+		bio->bi_size -= nbytes;
+		bio->bi_sector += (nbytes >> 9);
+		if (bio->bi_size == 0)
+			bio_endio(bio, bio->bi_size, error);
+	} else {
+
+		/*
+		 * Okay, this is the barrier request in progress, just
+		 * record the error;
+		 */
+		if (error && !q->orderr)
+			q->orderr = error;
+	}
 }
 
 /**
@@ -3388,8 +3402,7 @@ static int __end_that_request_first(struct request *req, int uptodate,
 		if (nr_bytes >= bio->bi_size) {
 			req->bio = bio->bi_next;
 			nbytes = bio->bi_size;
-			if (!ordered_bio_endio(req, bio, nbytes, error))
-				bio_endio(bio, nbytes, error);
+			req_bio_endio(req, bio, nbytes, error);
 			next_idx = 0;
 			bio_nbytes = 0;
 		} else {
@@ -3444,8 +3457,7 @@ static int __end_that_request_first(struct request *req, int uptodate,
 	 * if the request wasn't completed, update state
 	 */
 	if (bio_nbytes) {
-		if (!ordered_bio_endio(req, bio, bio_nbytes, error))
-			bio_endio(bio, bio_nbytes, error);
+		req_bio_endio(req, bio, bio_nbytes, error);
 		bio->bi_idx += next_idx;
 		bio_iovec(bio)->bv_offset += nr_bytes;
 		bio_iovec(bio)->bv_len -= nr_bytes;