Hi James, I posted a patch (as below) last year about this. http://www.kerneltrap.org/mailarchive/linux-scsi/2010/12/22/6887895 I intended to distinguish UA caused by media change from UA caused by other reasons like resetting a device. First, it should be notified to upper layer driver, sr, but the other must be retried as scsi_error.c coded. At least SCSI driver should not squash all UAs, I think. -- taruisi (2011/08/04 7:36), 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 <revers@xxxxxxxxxx> >>>> --- >>>> 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. > > James > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
