Re: [PATCH] 2.5.51 SCSI_IOCTL_GET_IDLUN + _GET_BUS_NUMBER

[Jens Axboe <axboe@suse.de>]

On Thu, Dec 12 2002, James Bottomley wrote:
> dougg@torque.net said:
> > For disks both the SCSI_IOCTL_GET_IDLUN and SCSI_IOCTL_GET_BUS_NUMBER
> > ioctls return the value 0 (type: int) in all cases. The attachment
> > removes the dummy definitions of these ioctls in driver/block/
> > scsi_ioctl.c so they fall through to the scsi mid level which
> > correctly implements them (at least in terms of lk 2.4). 
> 
> I'm not sure this is the correct thing to do.  These ioctls may be there 
> because cdrecord is using them.  In the new scheme, you can record a CD 
> without ever troubling the scsi mid-layer, so if cdrecord wants them, they 
> have to be provided in some fashion without relying on a fall through.
> 
> I've copied Jens on this mail, since he's the one that knows this stuff and 
> should be able to confirm or deny this suspicion.  Jens?

Hmm, I _may_ be wrong but I think the main reason for GET_IDLUN and
GET_BUS_NUMBER in the generic block layer is to stop them from failing
in libscg and thus fooling it into believing we are scsi. You would need
to check libscg/scsi-linux-sg.c to be sure.

For one thing, we need to maintain the behaviour we have now of _not_
failing them for ata devices. If you want to pass them down to SCSI as
well and get the right id/lun and bus, fine, but don't break the ata
one.

-- 
Jens Axboe