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 <[email protected]>
hjking · Feb 11, 2007 · 783660b · 783660b
1 parent cad9751
commit 783660b
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/block/elevator.c b/block/elevator.c
@@ -413,6 +413,8 @@ void elv_dispatch_sort(request_queue_t *q, struct request *rq)
 	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) {