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 DC01AC433F5 for ; Thu, 7 Apr 2022 14:32:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231252AbiDGOed (ORCPT ); Thu, 7 Apr 2022 10:34:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344006AbiDGOeW (ORCPT ); Thu, 7 Apr 2022 10:34:22 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9688D198526; Thu, 7 Apr 2022 07:32:12 -0700 (PDT) Received: from fraeml707-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4KZ3gw30svz681Z4; Thu, 7 Apr 2022 22:30:20 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml707-chm.china.huawei.com (10.206.15.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 7 Apr 2022 16:32:10 +0200 Received: from [10.47.80.129] (10.47.80.129) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 7 Apr 2022 15:32:09 +0100 Message-ID: <3e1914a8-5f6b-8fcf-7fb3-2d1edb9766e1@huawei.com> Date: Thu, 7 Apr 2022 15:32:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 From: John Garry Subject: Re: [PATCH 03/11] libata: Send internal commands through the block layer To: Christoph Hellwig CC: , , , , , , , , , , , , , References: <1647945585-197349-1-git-send-email-john.garry@huawei.com> <1647945585-197349-4-git-send-email-john.garry@huawei.com> <20220322112057.GC29270@lst.de> In-Reply-To: <20220322112057.GC29270@lst.de> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.80.129] X-ClientProxiedBy: lhreml728-chm.china.huawei.com (10.201.108.79) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/03/2022 11:20, Christoph Hellwig wrote: > On Tue, Mar 22, 2022 at 06:39:37PM +0800, John Garry wrote: >> When SCSI HBA device drivers are required to process an ATA internal >> command they still need a tag for the IO. This often requires the driver >> to set aside a set of tags for these sorts of IOs and manage the tags >> themselves. >> >> If we associate a SCSI command (and request) with an ATA internal command >> then the tag is already provided, so introduce the change to send ATA >> internal commands through the block layer with a set of custom blk-mq ops. >> >> note: I think that the timeout handling needs to be fixed up. Hi Christoph, > Any reason to not just send them through an ATA_16 passthrough CDB and > just use all the normal SCSI command handling? I had a go at implementing this but I have come up against a few issues: - ATA_16 handling translates the passthrough CDB to a ATA TF. However ata_exec_internal_sg() is passed a TF already. So what to do? Change the callers to generate a ATA_16 CDB? I guess not. Otherwise we could put the already-generated TF in the SCSI cmd CDB somehow and use directly. - We may have no SCSI device (yet) for the target when issuing an internal command, but only the ATA port+dev. So need a method to pass these pointers to ATA_16 handling - we would need to change ata_scsi_translate(), ata_scsi_pass_thru() and other friends to deal with ATA_TAG_INTERNAL and its peculiarities - today it just deals with regular qc's. It still does seem a reasonable idea to use ATA_16, but it looks like significant modifications would be required.... Thanks, John