From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D2C7C210F5A for ; Thu, 24 Apr 2025 09:03:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745485395; cv=none; b=VzWlKeD6HzTQnIp2Go8nDuo5zNN5GJ+9Co3gtoHUxA4bn/P1FOs/ueg5rxst7DBOjoa8UmVjDeTklKU5kMl3VsV3EhcFQ3SAS+i/VzxYp6EAr6JLmUqWPPocnIXR/YWs0ZjydfOnXDGD/OpbW0gEOs4l7Oc2EzDlRDtFzC4J0Kg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745485395; c=relaxed/simple; bh=LxxZ3PnM3GnSmQVc4b35vmUhaH1YtHOD2luSa1Hv2FA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=k9YdX0ZFXhPnGjnscPs0yDnDgGpeE0KfkrdDPurOaFQYVNxAVd8NsK55Jb3U7+vcGUwGPBt48NE/CQq75AILMWxnrrSSJZQlkAAn6hk4F4UkdDfiVxIT3wyyfn3tn+CwH2RoE43kroTufktBVVH/a1FysOXBsItVdJdUYwrRDqw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=WTIoglLA; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WTIoglLA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745485391; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=yQlNEGSJgij/t3GaaKCbDm9GBD8YV1Z5HMPR6Qwn3Uc=; b=WTIoglLAwCsjONgPVN/lCHkTDkABPk/XrsEOGGR07s/NT11rDNUd2CvoQiwwguO3Pm8+Jm xFfJFxEDbMK7rgiSIaD9TFMr4fEUilz3M8x9E8+In1RTFI1PjtFAblpE0v1fw+aaVb4CZs J2KUro2Vzf/5Gm9xjBWkBlXOaQbmPIA= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-146-fEpUFpxbOZGKJ5sRVGC3Mw-1; Thu, 24 Apr 2025 05:03:07 -0400 X-MC-Unique: fEpUFpxbOZGKJ5sRVGC3Mw-1 X-Mimecast-MFC-AGG-ID: fEpUFpxbOZGKJ5sRVGC3Mw_1745485386 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E95ED180036E; Thu, 24 Apr 2025 09:03:05 +0000 (UTC) Received: from fedora (unknown [10.72.116.127]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4303D1800374; Thu, 24 Apr 2025 09:03:00 +0000 (UTC) Date: Thu, 24 Apr 2025 17:02:56 +0800 From: Ming Lei To: Nilay Shroff Cc: Jens Axboe , linux-block@vger.kernel.org, Shinichiro Kawasaki , Thomas =?iso-8859-1?Q?Hellstr=F6m?= , Christoph Hellwig Subject: Re: [PATCH V2 13/20] block: unifying elevator change Message-ID: References: <20250418163708.442085-1-ming.lei@redhat.com> <20250418163708.442085-14-ming.lei@redhat.com> <28d4f3b8-1e42-451e-9754-ebf639b05aa2@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <28d4f3b8-1e42-451e-9754-ebf639b05aa2@linux.ibm.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On Sat, Apr 19, 2025 at 06:56:14PM +0530, Nilay Shroff wrote: > > > On 4/18/25 10:06 PM, Ming Lei wrote: > > elevator change is one well-define behavior: > > > > - tear down current elevator if it exists > > > > - setup new elevator > > > > It is supposed to cover any case for changing elevator by single > > internal API, typically the following cases: > > > > - setup default elevator in add_disk() > > > > - switch to none in del_disk() > > > > - reset elevator in blk_mq_update_nr_hw_queues() > > > > - switch elevator in sysfs `store` elevator attribute > > > > This patch uses elevator_change() to cover all above cases: > > > > - every elevator switch is serialized with each other: add_disk/del_disk/ > > store elevator is serialized already, blk_mq_update_nr_hw_queues() uses > > srcu for syncing with the other three cases > > > > - for both add_disk()/del_disk(), queue freeze works at atomic mode > > or has been froze, so the freeze in elevator_change() won't add extra > > delay > > > > - `struct elev_change_ctx` instance holds any info for changing elevator > > > > Signed-off-by: Ming Lei > > --- > > block/blk-sysfs.c | 18 ++++------- > > block/blk.h | 5 ++- > > block/elevator.c | 81 ++++++++++++++++++++++++++--------------------- > > block/elevator.h | 1 + > > block/genhd.c | 19 +---------- > > 5 files changed, 55 insertions(+), 69 deletions(-) > > > > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c > > index a2882751f0d2..58c50709bc14 100644 > > --- a/block/blk-sysfs.c > > +++ b/block/blk-sysfs.c > > @@ -869,14 +869,8 @@ int blk_register_queue(struct gendisk *disk) > > if (ret) > > goto out_unregister_ia_ranges; > > > > + elevator_set_default(q); > > mutex_lock(&q->elevator_lock); > > - if (q->elevator) { > > - ret = elv_register_queue(q, false); > > - if (ret) { > > - mutex_unlock(&q->elevator_lock); > > - goto out_crypto_sysfs_unregister; > > - } > > - } > > wbt_enable_default(disk); > > mutex_unlock(&q->elevator_lock); > > > [...] > [...] > > /* > > diff --git a/block/genhd.c b/block/genhd.c > > index 86c3db5b9305..de227aa923ed 100644 > > --- a/block/genhd.c > > +++ b/block/genhd.c > > @@ -438,12 +438,6 @@ static int __add_disk_fwnode(struct gendisk_data *data) > > */ > > if (disk->fops->submit_bio || disk->fops->poll_bio) > > return -EINVAL; > > - > > - /* > > - * Initialize the I/O scheduler code and pick a default one if > > - * needed. > > - */ > > - elevator_init_mq(disk->queue); > > } else { > > if (!disk->fops->submit_bio) > > return -EINVAL; > > @@ -587,11 +581,7 @@ static int __add_disk_fwnode(struct gendisk_data *data) > > if (disk->major == BLOCK_EXT_MAJOR) > > blk_free_ext_minor(disk->first_minor); > > out_exit_elevator: > > - if (disk->queue->elevator) { > > - mutex_lock(&disk->queue->elevator_lock); > > - elevator_exit(disk->queue); > > - mutex_unlock(&disk->queue->elevator_lock); > > - } > > + elevator_set_none(disk->queue); > > return ret; > > } > As we moved elevator init function (elevator_set_default) inside blk_register_queue, > we probably now don't need label out_exit_elevator in __add_disk_fwnode. In fact, > no code in __add_disk_fwnode shall jump to this label. > I think, elevator_set_none may be called anytime after we see failure post > blk_register_queue returns. Good catch, 'out_exit_elevator' can rename as 'out', and the last elevator_set_none() can be dropped. Thanks, Ming