Commit 8b70f45e authored Jun 02, 2015 by Akinobu Mita Committed by Jens Axboe Jun 01, 2015

null_blk: restart request processing on completion handler



When irqmode=2 (IRQ completion handler is timer) and queue_mode=1
(Block interface to use is rq), the completion handler should restart
request handling for any pending requests on a queue because request
processing stops when the number of commands are queued more than
hw_queue_depth (null_rq_prep_fn returns BLKPREP_DEFER).

Without this change, the following command cannot finish.

	# modprobe null_blk irqmode=2 queue_mode=1 hw_queue_depth=1
	# fio --name=t --rw=read --size=1g --direct=1 \
	  --ioengine=libaio --iodepth=64 --filename=/dev/nullb0

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 419c21a3

drivers/block/null_blk.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -243,6 +243,17 @@ static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
		cmd = container_of(entry, struct nullb_cmd, ll_list);
		entry = entry->next;
		end_cmd(cmd);

		if (cmd->rq) {
		struct request_queue *q = cmd->rq->q;

		if (!q->mq_ops && blk_queue_stopped(q)) {
		spin_lock(q->queue_lock);
		if (blk_queue_stopped(q))
		blk_start_queue(q);
		spin_unlock(q->queue_lock);
		}
		}
		} while (entry);
		}

		@@ -334,6 +345,7 @@ static int null_rq_prep_fn(struct request_queue q, struct request req)
		req->special = cmd;
		return BLKPREP_OK;
		}
		blk_stop_queue(q);

		return BLKPREP_DEFER;
		}