block: use rq complete marking in blk_abort_request()

We cannot abort a request if we raced with the timeout handler already,
or with the IO completion. So make blk_abort_request() mark the request
as complete, and only continue if we succeeded.

Found and suggested by Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/blk-timeout.c

@@ -158,6 +158,8 @@ void blk_rq_timed_out_timer(unsigned long data)
  */
 void blk_abort_request(struct request *req)
 {
+	if (blk_mark_rq_complete(req))
+		return;
 	blk_delete_timer(req);
 	blk_rq_timed_out(req);
 }