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 43EA1C43334 for ; Thu, 14 Jul 2022 03:41:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232198AbiGNDlK (ORCPT ); Wed, 13 Jul 2022 23:41:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232130AbiGNDlJ (ORCPT ); Wed, 13 Jul 2022 23:41:09 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 37FD725EB3 for ; Wed, 13 Jul 2022 20:41:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657770067; 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=3PqAwSujQrcFKBakWmxqsGxJDNIOKr6UoNvVqvwCEF4=; b=MmiaS8OhO/Vw1XlnNVqWgs3gEhj97Q7Sx6uOnFsK9mxfvdD89wnWszme+dI0amE20DB+MP jZ+5erJ/1KUERAHAEcA3jnYsSNZud1grxLfSQiu+Cg3lWIW8EUgRr4omOsn85YwyUVT0cB tgEggFpgb4/bD4Bgv3KydFir7DTO+/4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-498-lj0l3Q0eN2CkbUOOcky_hw-1; Wed, 13 Jul 2022 23:41:00 -0400 X-MC-Unique: lj0l3Q0eN2CkbUOOcky_hw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E77CB1C14487; Thu, 14 Jul 2022 03:40:59 +0000 (UTC) Received: from T590 (ovpn-8-16.pek2.redhat.com [10.72.8.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2D52C40CF8EE; Thu, 14 Jul 2022 03:40:51 +0000 (UTC) Date: Thu, 14 Jul 2022 11:40:46 +0800 From: Ming Lei To: Sagi Grimberg Cc: Jens Axboe , Kanchan Joshi , hch@lst.de, kbusch@kernel.org, io-uring@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, asml.silence@gmail.com, joshiiitr@gmail.com, anuj20.g@samsung.com, gost.dev@samsung.com, ming.lei@redhat.com Subject: Re: [PATCH for-next 3/4] io_uring: grow a field in struct io_uring_cmd Message-ID: References: <20220711110155.649153-1-joshi.k@samsung.com> <20220711110155.649153-4-joshi.k@samsung.com> <2b644543-9a54-c6c4-fd94-f2a64d0701fa@kernel.dk> <43955a42-7185-2afc-9a55-80cc2de53bf9@grimberg.me> <96fcba9a-76ad-8e04-e94e-b6ec5934f84e@grimberg.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <96fcba9a-76ad-8e04-e94e-b6ec5934f84e@grimberg.me> X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Mon, Jul 11, 2022 at 09:22:54PM +0300, Sagi Grimberg wrote: > > > > > Use the leftover space to carve 'next' field that enables linking of > > > > io_uring_cmd structs. Also introduce a list head and few helpers. > > > > > > > > This is in preparation to support nvme-mulitpath, allowing multiple > > > > uring passthrough commands to be queued. > > > > > > It's not clear to me why we need linking at that level? > > > > I think the attempt is to allow something like blk_steal_bios that > > nvme leverages for io_uring_cmd(s). > > I'll rephrase because now that I read it, I think my phrasing is > confusing. > > I think the attempt is to allow something like blk_steal_bios that > nvme leverages, but for io_uring_cmd(s). Essentially allow io_uring_cmd > to be linked in a requeue_list. io_uring_cmd is 1:1 with pt request, so I am wondering why not retry on io_uring_cmd instance directly via io_uring_cmd_execute_in_task(). I feels it isn't necessary to link io_uring_cmd into list. Thanks, Ming