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authorTejun Heo <htejun@gmail.com>2005-11-10 08:49:19 +0100
committerJens Axboe <axboe@nelson.home.kernel.dk>2005-11-12 10:55:51 +0100
commit1b5ed5e1f1315e37380e55102f58bcae3344d2a7 (patch)
tree785dc9675e2f22b60017030063ba103740c72f16 /block/cfq-iosched.c
parent407df2aa29a33fe16f6ee4bac8cdfa414783b9f1 (diff)
downloadlinux-2.6.34-ux500-1b5ed5e1f1315e37380e55102f58bcae3344d2a7.tar.gz
[BLOCK] cfq-iosched: cfq forced dispatching fix
cfq forced dispatching might not return all requests on the queue. This bug can hang elevator switchinig and corrupt request ordering during flush sequence. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jens Axboe <axboe@suse.de>
Diffstat (limited to 'block/cfq-iosched.c')
-rw-r--r--block/cfq-iosched.c54
1 files changed, 45 insertions, 9 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ecacca9c877..452538644bc 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -999,7 +999,7 @@ cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
/*
* get next queue for service
*/
-static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd, int force)
+static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
{
unsigned long now = jiffies;
struct cfq_queue *cfqq;
@@ -1023,7 +1023,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd, int force)
*/
if (!RB_EMPTY(&cfqq->sort_list))
goto keep_queue;
- else if (!force && cfq_cfqq_class_sync(cfqq) &&
+ else if (cfq_cfqq_class_sync(cfqq) &&
time_before(now, cfqq->slice_end)) {
if (cfq_arm_slice_timer(cfqd, cfqq))
return NULL;
@@ -1092,6 +1092,42 @@ __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
}
static int
+cfq_forced_dispatch_cfqqs(struct list_head *list)
+{
+ int dispatched = 0;
+ struct cfq_queue *cfqq, *next;
+ struct cfq_rq *crq;
+
+ list_for_each_entry_safe(cfqq, next, list, cfq_list) {
+ while ((crq = cfqq->next_crq)) {
+ cfq_dispatch_insert(cfqq->cfqd->queue, crq);
+ dispatched++;
+ }
+ BUG_ON(!list_empty(&cfqq->fifo));
+ }
+ return dispatched;
+}
+
+static int
+cfq_forced_dispatch(struct cfq_data *cfqd)
+{
+ int i, dispatched = 0;
+
+ for (i = 0; i < CFQ_PRIO_LISTS; i++)
+ dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]);
+
+ dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr);
+ dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);
+ dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
+
+ cfq_slice_expired(cfqd, 0);
+
+ BUG_ON(cfqd->busy_queues);
+
+ return dispatched;
+}
+
+static int
cfq_dispatch_requests(request_queue_t *q, int force)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
@@ -1100,7 +1136,10 @@ cfq_dispatch_requests(request_queue_t *q, int force)
if (!cfqd->busy_queues)
return 0;
- cfqq = cfq_select_queue(cfqd, force);
+ if (unlikely(force))
+ return cfq_forced_dispatch(cfqd);
+
+ cfqq = cfq_select_queue(cfqd);
if (cfqq) {
int max_dispatch;
@@ -1115,12 +1154,9 @@ cfq_dispatch_requests(request_queue_t *q, int force)
cfq_clear_cfqq_wait_request(cfqq);
del_timer(&cfqd->idle_slice_timer);
- if (!force) {
- max_dispatch = cfqd->cfq_quantum;
- if (cfq_class_idle(cfqq))
- max_dispatch = 1;
- } else
- max_dispatch = INT_MAX;
+ max_dispatch = cfqd->cfq_quantum;
+ if (cfq_class_idle(cfqq))
+ max_dispatch = 1;
return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
}