Re: rework check_disk_change()

[Hannes Reinecke]

On 9/2/20 5:38 PM, Douglas Gilbert wrote:
> On 2020-09-02 10:11 a.m., Christoph Hellwig wrote:
> > Hi Jens,
> >
> > this series replaced the not very nice check_disk_change() function with
> > a new bdev_media_changed that avoids having the ->revalidate_disk call
> > at its end.  As a result ->revalidate_disk can be removed from a lot of
> > drivers.
>
> For over 20 years the sg driver has been carrying this snippet that hangs
> off the completion callback:
>
>         if (driver_stat & DRIVER_SENSE) {
>                  struct scsi_sense_hdr ssh;
>
>                  if (scsi_normalize_sense(sbp, sense_len, &ssh)) {
>                          if (!scsi_sense_is_deferred(&ssh)) {
>                                  if (ssh.sense_key == UNIT_ATTENTION) {
>                                          if (sdp->device->removable)
>                                                  sdp->device->changed = 1;
>                                  }
>                          }
>                  }
>          }
>
> Is it needed? The unit attention (UA) may not be associated with the
> device changing. Shouldn't the SCSI mid-level monitor UAs if they
> impact the state of a scsi_device object?
We do; check scsi_io_completion_action() in drivers/scsi/scsi_lib.c
So I don't think you'd need to keep it in sg.c.

Cheers,

Hannes
--
Dr. Hannes Reinecke                Kernel Storage Architect
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