From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754234Ab1JLVXF (ORCPT ); Wed, 12 Oct 2011 17:23:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12609 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751344Ab1JLVXC (ORCPT ); Wed, 12 Oct 2011 17:23:02 -0400 From: Jeff Moyer To: linux-kernel@vger.kernel.org, jaxboe@fusionio.com Cc: tj@kernel.org, christophe@saout.de, dm-devel@redhat.com, msnitzer@redhat.com, Jeff Moyer Subject: [PATCH 1/2] blk-flush: move the queue kick into blk_insert_cloned_request Date: Wed, 12 Oct 2011 17:22:41 -0400 Message-Id: <1318454562-25291-2-git-send-email-jmoyer@redhat.com> In-Reply-To: <1318454562-25291-1-git-send-email-jmoyer@redhat.com> References: <1318454562-25291-1-git-send-email-jmoyer@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- block/blk-core.c | 2 ++ block/blk-flush.c | 1 - 2 files changed, 2 insertions(+), 1 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index d34433a..795154e 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 491eb30..0ff29c6 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; } -- 1.7.1