From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Subject: Re: [RFC PATCH] SCSI: Correct UA being ignored when notifying of media-changed Date: Wed, 03 Aug 2011 18:14:45 -0500 Message-ID: <4E39D665.5000303@cs.wisc.edu> References: <1312378758-17308-1-git-send-email-revers@redhat.com> <1312410128.2855.94.camel@mulgrave> <4E39CC32.70305@cs.wisc.edu> <1312410999.2855.97.camel@mulgrave> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from sabe.cs.wisc.edu ([128.105.6.20]:32817 "EHLO sabe.cs.wisc.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755566Ab1HCXLa (ORCPT ); Wed, 3 Aug 2011 19:11:30 -0400 In-Reply-To: <1312410999.2855.97.camel@mulgrave> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Rob Evers , linux-scsi@vger.kernel.org On 08/03/2011 05:36 PM, James Bottomley wrote: > On Wed, 2011-08-03 at 17:31 -0500, Mike Christie wrote: >> On 08/03/2011 05:22 PM, James Bottomley wrote: >>> On Wed, 2011-08-03 at 09:39 -0400, Rob Evers wrote: >>>> Unit attention commands are getting ignored when a dvd is >>>> replaced, resulting in errors when accessing the new dvd. >>>> >>>> This problem occurred when a system is booted in rescue >>>> mode via dvd and the dvd is then replaced with another dvd. >>>> Subsequent commands to a filesystem on the dvd, such as >>>> 'fsck' and 'restore' report errors. >>>> >>>> Solution suggested by Mike Christie. >>>> >>>> Signed-off-by: Rob Evers >>>> --- >>>> drivers/scsi/scsi_error.c | 4 ++++ >>>> 1 files changed, 4 insertions(+), 0 deletions(-) >>>> >>>> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c >>>> index a4b9cdb..725cc11 100644 >>>> --- a/drivers/scsi/scsi_error.c >>>> +++ b/drivers/scsi/scsi_error.c >>>> @@ -294,6 +294,10 @@ static int scsi_check_sense(struct scsi_cmnd *scmd) >>>> */ >>>> if (scmd->device->expecting_cc_ua) { >>>> scmd->device->expecting_cc_ua = 0; >>>> + if (sdev->removable) { >>>> + sdev->changed = 1; >>>> + return SUCCESS; >>>> + } >>> >>> Are you sure about this? We only set expecting_cc_ua if the device was >>> reset in error handling ... and there we definitely *don't* want to >>> trigger a medium change. >>> >> >> What is happening is that we have a quirky device, and when you switch >> CD/DVDs the first command times out, so the scsi error handler runs. >> That is why the above code was modified. Before the patch the scsi layer >> would just retry the IO, and sr would not see the sense and so it would >> not detect the media changed. So the above code was meant to work like >> UA code in scsi_io_completion. > > The SCSI standard requires all SCSI devices to return UA after a reset > (that's the reason for the code). So, if I put this patch in, every > removable device would be flagged as having changed media if we go into > an error handling situation and reset it. I don't think that's a good > idea to fix a single non-standard CD. > Yeah, ok. Agree with you.