From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chandra Seetharaman Subject: RE: [dm-devel] failover does not work with rdac device handler Date: Tue, 07 Oct 2008 12:19:06 -0700 Message-ID: <1223407146.14830.617.camel@chandra-ubuntu> References: <00FE57DD11E3A94893D5BD54C3358BE884BF36@AUSX3MPC128.aus.amer.dell.com> ,<1223081419.14830.585.camel@chandra-ubuntu> <1223322817.14830.593.camel@chandra-ubuntu> <1223345074.14830.601.camel@chandra-ubuntu> Reply-To: sekharan@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from e31.co.us.ibm.com ([32.97.110.149]:60335 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750983AbYJGTT6 (ORCPT ); Tue, 7 Oct 2008 15:19:58 -0400 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e31.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id m97JJuRK026017 for ; Tue, 7 Oct 2008 15:19:56 -0400 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id m97JJt95183854 for ; Tue, 7 Oct 2008 13:19:56 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m97JJQFg010002 for ; Tue, 7 Oct 2008 13:19:26 -0600 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Moger, Babu" Cc: device-mapper development , "linux-scsi@vger.kernel.org" Sorry, I sent an imcomplete patch. Here is the correct one. BTW, The panic you saw is caused by the line (one of the lines you added): dev = container_of(&scsi_dh_data, struct scsi_device, scsi_dh_data); in scsi_dh_release(). We cannot use pointer in a structure to get the parent structure. chandra Keep a reference count of attaches, so that same number of detaches are allowed. ----------- Signed-off-by: Chandra Seetharaman --- Index: linux-2.6.27-rc8-git5/drivers/scsi/device_handler/scsi_dh.c =================================================================== --- linux-2.6.27-rc8-git5.orig/drivers/scsi/device_handler/scsi_dh.c +++ linux-2.6.27-rc8-git5/drivers/scsi/device_handler/scsi_dh.c @@ -153,12 +153,28 @@ static int scsi_dh_handler_attach(struct if (sdev->scsi_dh_data) { if (sdev->scsi_dh_data->scsi_dh != scsi_dh) err = -EBUSY; - } else if (scsi_dh->attach) + else + kref_get(&sdev->scsi_dh_data->kref); + } else if (scsi_dh->attach) { err = scsi_dh->attach(sdev); + if (!err) { + kref_init(&sdev->scsi_dh_data->kref); + sdev->scsi_dh_data->sdev = sdev; + } + } return err; } +static void scsi_dh_release(struct kref *kref) +{ + struct scsi_dh_data *scsi_dh_data; + scsi_dh_data = container_of(kref, struct scsi_dh_data, kref); + + if (scsi_dh_data->scsi_dh && scsi_dh_data->scsi_dh->detach) + scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev); +} + /* * scsi_dh_handler_detach - Detach a device handler from a device * @sdev - SCSI device the device handler should be detached from @@ -176,11 +192,7 @@ static void scsi_dh_handler_detach(struc if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh) return; - if (!scsi_dh) - scsi_dh = sdev->scsi_dh_data->scsi_dh; - - if (scsi_dh && scsi_dh->detach) - scsi_dh->detach(sdev); + kref_put(&sdev->scsi_dh_data->kref, scsi_dh_release); } /* Index: linux-2.6.27-rc8-git5/include/scsi/scsi_device.h =================================================================== --- linux-2.6.27-rc8-git5.orig/include/scsi/scsi_device.h +++ linux-2.6.27-rc8-git5/include/scsi/scsi_device.h @@ -6,6 +6,7 @@ #include #include #include +#include #include #include @@ -191,6 +192,8 @@ struct scsi_device_handler { struct scsi_dh_data { struct scsi_device_handler *scsi_dh; + struct kref kref; + struct scsi_device *sdev; /* back reference */ char buf[0]; };