From e94d1d00463f6fdcef956828ff698a2bce3f7a8f Mon Sep 17 00:00:00 2001 From: Jeff Moyer Date: Mon, 17 Oct 2011 12:57:23 +0200 Subject: [PATCH] blk-flush: move the queue kick into commit e67b77c791ca2778198c9e7088f3266ed2da7a55 upstream. A dm-multipath user reported[1] a problem when trying to boot a kernel with commit 4853abaae7e4a2af938115ce9071ef8684fb7af4 (block: fix flush machinery for stacking drivers with differring flush flags) applied. It turns out that an empty flush request can be sent into blk_insert_flush. When the BUG_ON was fixed to allow for this, I/O on the underlying device would stall. The reason is that blk_insert_cloned_request does not kick the queue. In the aforementioned commit, I had added a special case to kick the queue if data was sent down but the queue flags did not require a flush. A better solution is to push the queue kick up into blk_insert_cloned_request. This patch, along with a follow-on which fixes the BUG_ON, fixes the issue reported. [1] http://www.redhat.com/archives/dm-devel/2011-September/msg00154.html Reported-by: Christophe Saout Signed-off-by: Jeff Moyer Acked-by: Tejun Heo Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/blk-core.c | 2 ++ block/blk-flush.c | 1 - 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/block/blk-core.c b/block/blk-core.c index d34433ae791..795154e54a7 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1725,6 +1725,8 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq) where = ELEVATOR_INSERT_FLUSH; add_acct_request(q, rq, where); + if (where == ELEVATOR_INSERT_FLUSH) + __blk_run_queue(q); spin_unlock_irqrestore(q->queue_lock, flags); return 0; diff --git a/block/blk-flush.c b/block/blk-flush.c index 89ae3b9bf7c..720ad607ff9 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -330,7 +330,6 @@ void blk_insert_flush(struct request *rq) if ((policy & REQ_FSEQ_DATA) && !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { list_add_tail(&rq->queuelist, &q->queue_head); - blk_run_queue_async(q); return; } -- 2.11.4.GIT