From 30996f40bffe73f05abb92a4cec254befa8cecf7 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 5 Oct 2009 11:03:39 +0200 Subject: [PATCH] cfq-iosched: fix issue with rq-rq merging and fifo list ordering cfq uses rq->start_time as the fifo indicator, but that field may get modified prior to cfq doing it's fifo list adjustment when a request gets merged with another request. This can cause the fifo list to become unordered. Reported-by: Corrado Zoccolo Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 9c4b679908f4..e7f9e4e3a270 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -827,8 +827,10 @@ cfq_merged_requests(struct request_queue *q, struct request *rq, * reposition in fifo if next is older than rq */ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && - time_before(next->start_time, rq->start_time)) + time_before(rq_fifo_time(next), rq_fifo_time(rq))) { list_move(&rq->queuelist, &next->queuelist); + rq_set_fifo_time(rq, rq_fifo_time(next)); + } cfq_remove_request(next); } @@ -1129,9 +1131,7 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) */ static struct request *cfq_check_fifo(struct cfq_queue *cfqq) { - struct cfq_data *cfqd = cfqq->cfqd; - struct request *rq; - int fifo; + struct request *rq = NULL; if (cfq_cfqq_fifo_expire(cfqq)) return NULL; @@ -1141,13 +1141,11 @@ static struct request *cfq_check_fifo(struct cfq_queue *cfqq) if (list_empty(&cfqq->fifo)) return NULL; - fifo = cfq_cfqq_sync(cfqq); rq = rq_entry_fifo(cfqq->fifo.next); - - if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) + if (time_before(jiffies, rq_fifo_time(rq))) rq = NULL; - cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq); + cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); return rq; } @@ -2130,6 +2128,7 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq) cfq_add_rq_rb(rq); + rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); list_add_tail(&rq->queuelist, &cfqq->fifo); cfq_rq_enqueued(cfqd, cfqq, rq); -- 2.30.2