On Mon, 9 Feb 2015, Oliver Neukum wrote:
> On Mon, 2015-02-09 at 11:10 -0500, Alan Stern wrote:
> > On Mon, 9 Feb 2015, Oliver Neukum wrote:
> >
> > > This is necessary to make some storage arrays work.
> > >
> > > Some storage devices have more than 8 LUNs. In addition
> > > you can hook up a WideSCSI bus to USB. In these cases even
> > > level 2 devices can have more than 8 devices. For them
> > > it is necessary to simply believe the class specific
> > > command and report its result back to the SCSI layer.
> > >
> > > Signed-off-by: Oliver Neukum <oneukum@xxxxxxx>
> > > ---
> > > drivers/usb/storage/usb.c | 6 ++++++
> > > 1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
> > > index d468d02..cf2fafb 100644
> > > --- a/drivers/usb/storage/usb.c
> > > +++ b/drivers/usb/storage/usb.c
> > > @@ -889,6 +889,12 @@ static void usb_stor_scan_dwork(struct work_struct *work)
> > > !(us->fflags & US_FL_SCM_MULT_TARG)) {
> > > mutex_lock(&us->dev_mutex);
> > > us->max_lun = usb_stor_Bulk_max_lun(us);
> > > + /*
> > > + * Allow proper scanning of devices that present more than 8 LUNs
> > > + * While not affecting other devices that may need the previous behavior
> > > + */
> > > + if (us->max_lun > 8)
> >
> > >= 8, not > 8. Or, if you prefer, > 7.
> >
> > > + us_to_host(us)->max_lun = us->max_lun+1;
> >
> > What about the fact that you may be overriding max_scsi_luns?
>
> As far as I can tell scsi_sequential_lun_scan() will prevent that by
> max_dev_lun = min(max_scsi_luns, shost->max_lun);
Yes, all right.
> > Also, since the protocol allows only 4 bits for the LUN value, would it
> > be safer to use min(us->max_lun+1, 16)?
>
> usb_stor_Bulk_max_lun() will always return a number between 0 and 15
Ah, okay. I was looking at an old version of that routine.
However, I think you still need to change "> 8" above to ">= 8". Or to
"> 7".
Alan Stern
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