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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C56B2C433EF for ; Tue, 11 Jan 2022 18:21:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242284AbiAKSVx (ORCPT ); Tue, 11 Jan 2022 13:21:53 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:30442 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242057AbiAKSVw (ORCPT ); Tue, 11 Jan 2022 13:21:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641925312; 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=5BL/Z9jZkrOVYFK7HhKccychDhStBWbDZbasY7oM2OA=; b=PszB0HvHHMB8sAdqzzVBoIJhedXpwXWk3LumMYAT56HR/hPo/5WNBPK7joV0qvz1WleUF7 o0ZKUsLbyUdZ5jV6GOOs6c7xheFMN0oW1FDNlYAEbWP98quc2WnIOWIJmZ/kw74rx6PByV IUmh7W/AxDbOx0Iq2PyWL9phinJomvE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-564-nGqmbmKKO_uDREgOHCH5kA-1; Tue, 11 Jan 2022 13:21:49 -0500 X-MC-Unique: nGqmbmKKO_uDREgOHCH5kA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0BC75100F944; Tue, 11 Jan 2022 18:21:48 +0000 (UTC) Received: from segfault.boston.devel.redhat.com (segfault.boston.devel.redhat.com [10.19.60.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 053C67A3F6; Tue, 11 Jan 2022 18:21:22 +0000 (UTC) From: Jeff Moyer To: Christoph Hellwig Cc: Mike Snitzer , Jens Axboe , dm-devel@redhat.com, linux-block@vger.kernel.org, Ming Lei Subject: Re: [dm-devel] [PATCH 0/3] blk-mq/dm-rq: support BLK_MQ_F_BLOCKING for dm-rq References: <20211221141459.1368176-1-ming.lei@redhat.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 Date: Tue, 11 Jan 2022 13:23:53 -0500 In-Reply-To: (Christoph Hellwig's message of "Tue, 11 Jan 2022 00:34:30 -0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Christoph Hellwig writes: > On Tue, Dec 28, 2021 at 04:30:08PM -0500, Mike Snitzer wrote: >> Yeah, people use request-based for IO scheduling and more capable path >> selectors. Imposing bio-based would be a pretty jarring workaround for >> BLK_MQ_F_BLOCKING. request-based DM should properly support it. > > Given that nvme-tcp is the only blocking driver that has multipath > driver that driver explicitly does not intend to support dm-multipath > I'm absolutely against adding block layer cruft for this particular > use case. Maybe I have bad taste, but the patches didn't look like cruft to me. :) I'm not sure why we'd prevent users from using dm-mpath on nvmeof. I think there's agreement that the nvme native multipath implementation is the preferred way (that's the default in rhel9, even), but I don't think that's a reason to nack this patch set. Or have I missed your point entirely? Thanks! Jeff