From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFE2AC3A5A8 for ; Wed, 4 Sep 2019 09:29:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2DA12339D for ; Wed, 4 Sep 2019 09:29:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727768AbfIDJ3n (ORCPT ); Wed, 4 Sep 2019 05:29:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60470 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725840AbfIDJ3m (ORCPT ); Wed, 4 Sep 2019 05:29:42 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6F9A57FDE9; Wed, 4 Sep 2019 09:29:42 +0000 (UTC) Received: from ming.t460p (ovpn-8-23.pek2.redhat.com [10.72.8.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1323160625; Wed, 4 Sep 2019 09:29:21 +0000 (UTC) Date: Wed, 4 Sep 2019 17:29:17 +0800 From: Ming Lei To: Damien Le Moal Cc: linux-block@vger.kernel.org, Jens Axboe , linux-scsi@vger.kernel.org, "Martin K . Petersen" , Mike Snitzer , dm-devel@redhat.com Subject: Re: [PATCH v3 5/7] block: Delay default elevator initialization Message-ID: <20190904092915.GF7578@ming.t460p> References: <20190904084247.23338-1-damien.lemoal@wdc.com> <20190904084247.23338-6-damien.lemoal@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190904084247.23338-6-damien.lemoal@wdc.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 04 Sep 2019 09:29:42 +0000 (UTC) Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On Wed, Sep 04, 2019 at 05:42:45PM +0900, Damien Le Moal wrote: > When elevator_init_mq() is called from blk_mq_init_allocated_queue(), > the only information known about the device is the number of hardware > queues as the block device scan by the device driver is not completed > yet. The device type and the device required features are not set yet, > preventing to correctly choose the default elevator most suitable for > the device. > > This currently affects all multi-queue zoned block devices which default > to the "none" elevator instead of the required "mq-deadline" elevator. > These drives currently include host-managed SMR disks connected to a > smartpqi HBA and null_blk block devices with zoned mode enabled. > Upcoming NVMe Zoned Namespace devices will also be affected. > > Fix this by moving the execution of elevator_init_mq() from > blk_mq_init_allocated_queue() into __device_add_disk() to allow for the > device driver to probe the device characteristics and set attributes > of the device request queue prior to the elevator initialization. > > Also to make sure that the elevator initialization is never done while > requests are in-flight (there should be none when the device driver > calls device_add_disk()), freeze and quiesce the device request queue > before executing blk_mq_init_sched(). > > Signed-off-by: Damien Le Moal > --- > block/blk-mq.c | 2 -- > block/elevator.c | 7 +++++++ > block/genhd.c | 8 ++++++++ > 3 files changed, 15 insertions(+), 2 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index ee4caf0c0807..a37503984206 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -2902,8 +2902,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, > blk_mq_add_queue_tag_set(set, q); > blk_mq_map_swqueue(q); > > - elevator_init_mq(q); > - > return q; > > err_hctxs: > diff --git a/block/elevator.c b/block/elevator.c > index 520d6b224b74..096a670d22d7 100644 > --- a/block/elevator.c > +++ b/block/elevator.c > @@ -712,7 +712,14 @@ void elevator_init_mq(struct request_queue *q) > if (!e) > return; > > + blk_mq_freeze_queue(q); > + blk_mq_quiesce_queue(q); > + > err = blk_mq_init_sched(q, e); > + > + blk_mq_unquiesce_queue(q); > + blk_mq_unfreeze_queue(q); > + > if (err) { > pr_warn("\"%s\" elevator initialization failed, " > "falling back to \"none\"\n", e->elevator_name); > diff --git a/block/genhd.c b/block/genhd.c > index 54f1f0d381f4..7380dd7b2257 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -695,6 +695,13 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk, > dev_t devt; > int retval; > > + /* > + * The disk queue should now be all set with enough information about > + * the device for the elevator code to pick an adequate default > + * elevator. > + */ > + elevator_init_mq(disk->queue); > + For dm-rq, add_disk_no_queue_reg() is called before blk_mq_init_allocated_queue(). That means this patch actually sets elevator early for dm-rq, and I guess this way may not work as expected since hw/sw queues aren't allocated yet. Thanks, Ming