Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933491AbdGKPce (ORCPT ); Tue, 11 Jul 2017 11:32:34 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:42276 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933461AbdGKPcc (ORCPT ); Tue, 11 Jul 2017 11:32:32 -0400 Subject: Re: [PATCH v2 1/4] scsi: scsi_dh_alua: allow I/O in target port unavailable and standby states To: Hannes Reinecke Cc: jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, bart.vanassche@sandisk.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <1499726857-7875-1-git-send-email-mauricfo@linux.vnet.ibm.com> <1499726857-7875-2-git-send-email-mauricfo@linux.vnet.ibm.com> From: Mauricio Faria de Oliveira Date: Tue, 11 Jul 2017 12:32:15 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable x-cbid: 17071115-1523-0000-0000-000002B41A07 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17071115-1524-0000-0000-00002A4D479A Message-Id: <224d8cd3-478c-2440-3479-0119885575cf@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-11_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1707110247 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1098 Lines: 33 On 07/11/2017 06:18 AM, Hannes Reinecke wrote: > NACK. > > The whole_point_ of having device handlers is to_avoid_ I/O errors > during booting. > > And the ALUA checker is prepared to handle this situation properly. > The directio checker of course doesn't know about this, but then no-one > expected the directio checker to work with ALUA. I lacked that more holistic understanding. Thanks for explaining. Now, for the sake of logging/debugging... Any problem with patches 2 and 4? Also, it seems the Unavailable/Standby states would not be logged without a recheck from alua_check_sense(), since the only callers of alua_rtpg_queue() are alua_activate() and alua_check[_sense]() [the call from alua_check_vpd() is only in the initialization path]. Isn't there a point in scheduling a recheck once those conditions are found in alua_check_sense() to get them logged? - since valid path checkers won't go through that function. (and it occurred to me that the state-change check of patch 3 can be done there, simpler.) cheers, -- Mauricio Faria de Oliveira IBM Linux Technology Center