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authorJens Axboe <jens.axboe@oracle.com>2009-10-05 11:03:39 +0200
committerJens Axboe <jens.axboe@oracle.com>2009-10-05 11:03:39 +0200
commit30996f40bffe73f05abb92a4cec254befa8cecf7 (patch)
tree2ce2cf9ed92aff3f930b7553711f4b439d6cb89e /block
parent374576a8b6f865022c0fd1ca62396889b23d66dd (diff)
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 <czoccolo@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c15
1 files changed, 7 insertions, 8 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9c4b679908f..e7f9e4e3a27 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);