linux-kernel - [PATCH 006 of 35] Only call bi_end

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Date:	Tue, 31 Jul 2007 12:16:17 +1000
From:	NeilBrown <neilb@...e.de>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH 006 of 35] Only call bi_end_io once for any bio.


Current bi_end_io can be called multiple times as sub-requests complete.
However no ->bi_end_io function wants to know about that.  So
only call when the bio is complete.

Note that bi_sector and bi_size are now not updated when subrequests
complete.  This does not appear to be a problem as they are not
used (any longer) once a bio has been attached to a request,
except where bi_size is offset by rq->first_offset.

This allows us to remove q->bi_size as it is no longer needed.

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

### Diffstat output
 ./block/ll_rw_blk.c      |   20 +++-----------------
 ./include/linux/blkdev.h |    1 -
 2 files changed, 3 insertions(+), 18 deletions(-)

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
--- .prev/block/ll_rw_blk.c	2007-07-31 11:20:46.000000000 +1000
+++ ./block/ll_rw_blk.c	2007-07-31 11:20:47.000000000 +1000
@@ -430,7 +430,6 @@ static void queue_flush(struct request_q
 static inline struct request *start_ordered(struct request_queue *q,
 					    struct request *rq)
 {
-	q->bi_size = 0;
 	q->orderr = 0;
 	q->ordered = q->next_ordered;
 	q->ordseq |= QUEUE_ORDSEQ_STARTED;
@@ -530,23 +529,17 @@ int blk_do_ordered(struct request_queue 
 
 static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error)
 {
-	struct request_queue *q = bio->bi_private;
 
 	/*
 	 * This is dry run, restore bio_sector and size.  We'll finish
 	 * this request again with the original bi_end_io after an
 	 * error occurs or post flush is complete.
 	 */
-	q->bi_size += bytes;
-
-	if (bio->bi_size)
-		return 1;
 
 	/* Reset bio */
 	set_bit(BIO_UPTODATE, &bio->bi_flags);
-	bio->bi_size = q->bi_size;
-	bio->bi_sector -= (q->bi_size >> 9);
-	q->bi_size = 0;
+	bio->bi_size = bytes;
+	bio->bi_sector -= (bytes >> 9);
 
 	return 0;
 }
@@ -3473,14 +3466,7 @@ static int __end_that_request_first(stru
 	if (!req->bio)
 		return 0;
 
-	/*
-	 * 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->first_offset = bio_nbytes;
-	}
+	req->first_offset = bio_nbytes;
 
 	blk_recalc_rq_sectors(req, total_bytes >> 9);
 	blk_recalc_rq_segments(req);

diff .prev/include/linux/blkdev.h ./include/linux/blkdev.h
--- .prev/include/linux/blkdev.h	2007-07-31 11:20:46.000000000 +1000
+++ ./include/linux/blkdev.h	2007-07-31 11:20:47.000000000 +1000
@@ -472,7 +472,6 @@ struct request_queue
 	int			orderr, ordcolor;
 	struct request		pre_flush_rq, bar_rq, post_flush_rq;
 	struct request		*orig_bar_rq;
-	unsigned int		bi_size;
 
 	struct mutex		sysfs_lock;
 
-
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