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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 9DECEC43441 for ; Wed, 14 Nov 2018 16:47:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D62E22360 for ; Wed, 14 Nov 2018 16:47:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5D62E22360 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728045AbeKOCvl (ORCPT ); Wed, 14 Nov 2018 21:51:41 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:34344 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728085AbeKOCvl (ORCPT ); Wed, 14 Nov 2018 21:51:41 -0500 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wAEGjuAx129677 for ; Wed, 14 Nov 2018 11:47:43 -0500 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2nrmqvhrpg-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 14 Nov 2018 11:46:29 -0500 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 14 Nov 2018 16:44:31 -0000 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wAEGiUtl56164552 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 14 Nov 2018 16:44:30 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A13125204F; Wed, 14 Nov 2018 16:44:30 +0000 (GMT) Received: from w530-pk1mzal (unknown [9.152.212.21]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTPS id 8D51F52059; Wed, 14 Nov 2018 16:44:30 +0000 (GMT) Received: from bblock by w530-pk1mzal with local (Exim 4.91) (envelope-from ) id 1gMyHG-0001sV-A2; Wed, 14 Nov 2018 17:44:30 +0100 Date: Wed, 14 Nov 2018 17:44:30 +0100 From: Benjamin Block To: Christoph Hellwig Cc: axboe@kernel.dk, martin.petersen@oracle.com, ooo@electrozaur.com, Johannes Thumshirn , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 6/8] bsg-lib: handle bidi requests without block layer help References: <20181111133211.13926-1-hch@lst.de> <20181111133211.13926-7-hch@lst.de> <20181113143520.GB7222@w530-pk1mzal> <20181114154857.GA28985@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20181114154857.GA28985@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 x-cbid: 18111416-0012-0000-0000-000002CA7AC0 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18111416-0013-0000-0000-000020FF8E03 Message-Id: <20181114164430.GC7222@w530-pk1mzal> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-11-14_13:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 lowpriorityscore=0 mlxlogscore=916 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1811140151 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Nov 14, 2018 at 04:48:57PM +0100, Christoph Hellwig wrote: > On Tue, Nov 13, 2018 at 03:35:20PM +0100, Benjamin Block wrote: > > This seems like a non-obvious user-breakage. So apart from removing the > > in-kernel stuff that uses bidirectional commands you also forbid > > userspace from every using them? That seems wrong to me. > > > > There is other SCSI Command Sets than OSD that provide bidirectional > > commands, even SBC has some (i.e. X*WRITE*, COMPARE AND WRITE). > > Yes, there are a few. But the only driver that even supports them > right now is iscsi_tcp to start with, and we have to drag a significant > amount of code around just to support this corner case. > But we are not talking about kernel-support here, this interface is user-facing, and for an interfaces that was made so people could send arbitrary SCSI commands, that the kernel doesn't support. Its probably also more complicated to make sure that no one is using that, in contrast to the OSD stuff that - as state in the patch-letter - never made it out of academia. Its not like anyone has to release anything open if they use BSG/SG, its just syscalls after all. -- With Best Regards, Benjamin Block / Linux on IBM Z Kernel Development IBM Systems & Technology Group / IBM Deutschland Research & Development GmbH Vorsitz. AufsR.: Martina Koederitz / Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen / Registergericht: AmtsG Stuttgart, HRB 243294