[PATCH 001 of 5] Don't update bi_hw_*_size if we aren't going to merge.

[NeilBrown <neilb@suse.de>]

ll_merge_requests_fn can update bi_hw_*_size in one case where we end
up not merging.  This is wrong.

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

### Diffstat output
 ./block/ll_rw_blk.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
--- .prev/block/ll_rw_blk.c	2007-08-16 14:57:39.000000000 +1000
+++ ./block/ll_rw_blk.c	2007-08-16 15:02:29.000000000 +1000
@@ -1518,11 +1518,13 @@ static int ll_merge_requests_fn(struct r
 		/*
 		 * propagate the combined length to the end of the requests
 		 */
+		total_hw_segments--;
+		if (total_hw_segments > q->max_hw_segments)
+			return 0;
 		if (req->nr_hw_segments == 1)
 			req->bio->bi_hw_front_size = len;
 		if (next->nr_hw_segments == 1)
 			next->biotail->bi_hw_back_size = len;
-		total_hw_segments--;
 	}
 
 	if (total_hw_segments > q->max_hw_segments)