[PATCH] fix queue stalling while barrier sequencing
If ordered tag isn't supported, request ordering for barrier sequencing is performed by queue draining, which basically hangs the request queue until elv_completed_request() reports completion of all previous fs requests. The condition check in elv_completed_request() was only performed for fs requests. If a special request is queued between the last to-be-drained request and the barrier sequence, draining is never completed and the queue is stalled forever. This patch moves the end-of-draining condition check such that it's performed for all requests. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jens Axboe <axboe@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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1 changed files with 10 additions and 10 deletions
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@ -610,23 +610,23 @@ void elv_completed_request(request_queue_t *q, struct request *rq)
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* request is released from the driver, io must be done
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*/
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if (blk_account_rq(rq)) {
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struct request *first_rq = list_entry_rq(q->queue_head.next);
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q->in_flight--;
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if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)
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e->ops->elevator_completed_req_fn(q, rq);
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}
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/*
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* Check if the queue is waiting for fs requests to be
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* drained for flush sequence.
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*/
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if (q->ordseq && q->in_flight == 0 &&
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/*
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* Check if the queue is waiting for fs requests to be
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* drained for flush sequence.
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*/
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if (unlikely(q->ordseq)) {
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struct request *first_rq = list_entry_rq(q->queue_head.next);
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if (q->in_flight == 0 &&
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blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
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blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) {
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blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
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q->request_fn(q);
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}
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if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)
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e->ops->elevator_completed_req_fn(q, rq);
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}
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}
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