commit 783660b2f60418144e168ab75a06786f9695fc70
author Jens Axboe <jens.axboe@oracle.com> Fri Jan 19 11:27:47 2007 +1100
committer Jens Axboe <axboe@carl.home.kernel.dk> Sun Feb 11 23:14:44 2007 +0100
tree c25135f978bb2b400852b8aa27458a6d1649e999
parent cad9751642b62cbb5f62feedc546b4f7890497d4

elevator: don't sort reads between writes

Don't allow elv_dispatch_sort() to mix reads and writes together,
it's rarely a good idea.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/elevator.c

diff --git a/block/elevator.c b/block/elevator.c
index d037623..25f6ef2 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -413,6 +413,8 @@
 	list_for_each_prev(entry, &q->queue_head) {
 		struct request *pos = list_entry_rq(entry);
 
+		if (rq_data_dir(rq) != rq_data_dir(pos))
+			break;
 		if (pos->cmd_flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED))
 			break;
 		if (rq->sector >= boundary) {