Re: [Bug 80711] [PATCH]SG_FLAG_LUN_INHIBIT is no longer implemented and there's not way to prevent the kernel from using the 2nd cdb byte for the LUN

Christoph Hellwig
2014-08-21T21:57:56Z

On Thu, Aug 21, 2014 at 05:43:41PM -0400, Martin K. Petersen wrote:
> Alan> Okay, here's a patch that implements the suggestion, except that I
> Alan> put the flag in the Scsi_Host structure instead of the template.
> Alan> This was to minimize the impact of the change. Among the various
> Alan> SCSI-over-USB transports, only the Bulk-Only transport gives the
> Alan> LUN separately from the CDB. I don't know if there are any
> Alan> multi-LUN USB devices that don't use the Bulk-Only transport, but
> Alan> if there are then they won't work if the LUN isn't stored in
> Alan> CDB[1].
>
> I'm in agreement with this approach.

I like it too. One idea to unclutter the fastpath would be to have a
single flag that controls if the LUN is set which is based on the
host(-template) flag and the scsi level, which would allow us to remove
all the clutter around that area.