Commit 6077c2d7 authored Apr 07, 2017 by Bart Van Assche Committed by Jens Axboe Apr 07, 2017

dm rq: Avoid that request processing stalls sporadically



While running the srp-test software I noticed that request
processing stalls sporadically at the beginning of a test, namely
when mkfs is run against a dm-mpath device. Every time when that
happened the following command was sufficient to resume request
processing:

    echo run >/sys/kernel/debug/block/dm-0/state

This patch avoids that such request processing stalls occur. The
test I ran is as follows:

    while srp-test/run_tests -d -r 30 -t 02-mq; do :; done

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 36e3cf27

drivers/md/dm-rq.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -755,6 +755,7 @@ static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
		/* Undo dm_start_request() before requeuing */
		rq_end_stats(md, rq);
		rq_completed(md, rq_data_dir(rq), false);
		blk_mq_delay_run_hw_queue(hctx, 100/ms/);
		return BLK_MQ_RQ_QUEUE_BUSY;
		}

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