Re: [PATCH] Revert "virtio-scsi: Send "REPORTED LUNS CHANGED" sense data upon disk hotplug events"

[Paolo Bonzini]

On 7/12/23 15:40, Christoph Hellwig wrote:
> > The problem is that the SCSI stack does not send this command, so we
> > should do it in the driver. In fact we do it for
> > VIRTIO_SCSI_EVT_RESET_RESCAN (hotplug), but not for
> > VIRTIO_SCSI_EVT_RESET_REMOVED (hotunplug).
>
> No, you should absolutely no do it in the driver.  The fact that
> virtio-scsi even tries to do some of its own LUN scanning is
> problematic and should have never happened.

I agree that it should not do it for hot-unplug.  However, for hot-plug 
the spec says that a hotplug event for LUN 0 represents the addition of 
an entire target, so why is it incorrect to start a REPORT LUNS scan if 
the host doesn't tell you the exact LUN(s) that have been added?

There is a similar case in mpi3mr/mpi3mr_os.c, though it's only scanning 
for newly added devices after a controller reset.

Paolo