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=-13.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 B8C6CC433E7 for ; Mon, 31 Aug 2020 07:30:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9EB8F206F0 for ; Mon, 31 Aug 2020 07:30:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727116AbgHaHaA (ORCPT ); Mon, 31 Aug 2020 03:30:00 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:10352 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725794AbgHaHaA (ORCPT ); Mon, 31 Aug 2020 03:30:00 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 976326E2594D1CC70A1E; Mon, 31 Aug 2020 15:29:56 +0800 (CST) Received: from [127.0.0.1] (10.174.179.92) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.487.0; Mon, 31 Aug 2020 15:29:49 +0800 Subject: Re: [PATCH v1] scsi: libsas: set data_dir as DMA_NONE if libata mark qc as NODATA To: Luo Jiaxing , , CC: , , , , References: <1598426666-54544-1-git-send-email-luojiaxing@huawei.com> From: Jason Yan Message-ID: Date: Mon, 31 Aug 2020 15:29:49 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <1598426666-54544-1-git-send-email-luojiaxing@huawei.com> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.92] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2020/8/26 15:24, Luo Jiaxing дµÀ: > We found that it will fail every time when set feature to SATA disk by > "sdparm -s WCE=0 /dev/sde". > > After checking protocol, we know that MODE SELECT is the SCSI command for > setting WCE, and it do not exist in the SATA protocol. Therefore, this > commands are encapsulated in the SET FEATURE command in SATA protocol. > The difference is that the MODE SELECT command sent to SAS disk contains > data and is sent through the DMA. But when send to SATA disk through > SET FEATURE command, it does not contain data. > > I think libsas was not thorough enough in dealing with the situation, at > sas_ata_qc_issue(), task->dma_dir is inherited from qc->dma_dir(qc->dma_dir > is also inherited from SCSI). However, in ATA driver, if qc->tf.protocol is > set to ATA_PROT_NODATA, ata_sg_setup() will not invoked by ata_qc_issue(). > It mean that ATA didn't use dma_dir and it's not reliable. So, if libsas > still inherits from qc->dma_dir when there is no data need to be send. As a > result, task with no data are mistakenly considered as carrying data and it > will make LLDD report an error on IO completion. > > So, When ATA driver mark tf->protocol as NODATA, dma_dir should be set as > DMA_NONE. And we can see WCE is successfully disable for SATA disk then. > > Euler:~ # sdparm -s WCE=0 /dev/sde > /dev/sde: ATA ST4000NM0035-1V4 TN03 > Euler:~ # sdparm /dev/sde > /dev/sde: ATA ST4000NM0035-1V4 TN03 > Read write error recovery mode page: > AWRE 1 [cha: n, def: 1] > ARRE 0 [cha: n, def: 0] > PER 0 [cha: n, def: 0] > Caching (SBC) mode page: > WCE 0 [cha: y, def: 0] > RCD 0 [cha: n, def: 0] > Control mode page: > SWP 0 [cha: n, def: 0] > > Fixes: fa1c1e8f1ece ("[SCSI] Add SATA support to libsas") > > Signed-off-by: Luo Jiaxing > Reviewed-by: John Garry > --- > drivers/scsi/libsas/sas_ata.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c > index 6a521ba..a488798 100644 > --- a/drivers/scsi/libsas/sas_ata.c > +++ b/drivers/scsi/libsas/sas_ata.c > @@ -209,7 +209,10 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc) > task->num_scatter = si; > } > > - task->data_dir = qc->dma_dir; > + if (qc->tf.protocol == ATA_PROT_NODATA) > + task->data_dir = DMA_NONE; > + else > + task->data_dir = qc->dma_dir; > task->scatter = qc->sg; > task->ata_task.retry_count = 1; > task->task_state_flags = SAS_TASK_STATE_PENDING; > Reviewed-by: Jason Yan