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author | Tejun Heo <htejun@gmail.com> | 2005-11-10 07:49:19 (GMT) |
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committer | Jens Axboe <axboe@nelson.home.kernel.dk> | 2005-11-12 09:55:51 (GMT) |
commit | 1b5ed5e1f1315e37380e55102f58bcae3344d2a7 (patch) | |
tree | 785dc9675e2f22b60017030063ba103740c72f16 /block/cfq-iosched.c | |
parent | 407df2aa29a33fe16f6ee4bac8cdfa414783b9f1 (diff) | |
download | linux-fsl-qoriq-1b5ed5e1f1315e37380e55102f58bcae3344d2a7.tar.xz |
[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.c | 54 |
1 files changed, 45 insertions, 9 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index ecacca9..4525386 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); } |