From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936179Ab1KJD7T (ORCPT ); Wed, 9 Nov 2011 22:59:19 -0500 Received: from cantor2.suse.de ([195.135.220.15]:45015 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965932Ab1KJDrW (ORCPT ); Wed, 9 Nov 2011 22:47:22 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Nov 9 13:32:05 2011 Message-Id: <20111109213205.648847340@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 09 Nov 2011 13:34:37 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jeff Moyer , Tejun Heo , Jens Axboe Subject: [230/264] blk-flush: move the queue kick into In-Reply-To: <20111109213508.GA3476@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeff Moyer 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(-) --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1725,6 +1725,8 @@ int blk_insert_cloned_request(struct req 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; --- 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; }