Reattach/redetect allways connected umass device - is it possible ?

[M. Warner Losh]

In message: <20050328144135.GI14532 at cicely12.cicely.de>
            Bernd Walter <ticso at cicely12.cicely.de> writes:
: On Mon, Mar 28, 2005 at 04:38:02PM +0200, Bernd Walter wrote:
: > On Mon, Mar 28, 2005 at 04:24:30PM +0200, Poul-Henning Kamp wrote:
: > > In message <20050328134856.GF14532 at cicely12.cicely.de>, Bernd Walter writes:
: > > 
: > > >> Driver support for this is not really meaterialized and therefore
: > > >> the model now is that when the media is ejected the geom device
: > > >> is removed and a new one created right away, even if a new media
: > > >> is not inserted right away.
: > > >
: > > >Do you get eject notifications from any device type?
: > > 
: > > Right now I belive floppy disks DTRT.
: > 
: > Interesting.
: > 
: > > >One of my problems is that it is possible with SCSI MO drives to
: > > >eject the media, reinsert a new one and errously continue to work
: > > >with the old GEOM layout.
: > > >I already trashed the data on one media by forgetting to trigger
: > > >a reprobe - since then I use a mount script.
: > > 
: > > Well, I have no idea how to pull the information out of the CAM/SCSI
: > > code, but I'm sure there is _some_ way it can be done.
: > 
: > There is the test unit ready command.
: > Either it returns OK, or you may get usefull sense data.
: > Here is an example:
: 
: This even works for my USB flash drives:
: [67]cicely13# camcontrol tur -n da -u 1 -v
: Unit is not ready
: (pass1:umass-sim0:0:0:0): TEST UNIT READY. CDB: 0 0 0 0 0 0 
: (pass1:umass-sim0:0:0:0): CAM Status: SCSI Status Error
: (pass1:umass-sim0:0:0:0): SCSI Status: Check Condition
: (pass1:umass-sim0:0:0:0): NOT READY asc:3a,0
: (pass1:umass-sim0:0:0:0): Medium not present
: Exit 1
: [68]cicely13# camcontrol tur -n da -u 1 -v
: Unit is not ready
: (pass1:umass-sim0:0:0:0): TEST UNIT READY. CDB: 0 0 0 0 0 0 
: (pass1:umass-sim0:0:0:0): CAM Status: SCSI Status Error
: (pass1:umass-sim0:0:0:0): SCSI Status: Check Condition
: (pass1:umass-sim0:0:0:0): UNIT ATTENTION asc:28,0
: (pass1:umass-sim0:0:0:0): Not ready to ready change, medium may have changed
: Exit 1
: [69]cicely13# camcontrol tur -n da -u 1 -v
: Unit is ready
: 
: [71]cicely13# camcontrol tur -n da -u 4 -v
: Unit is not ready
: (pass4:umass-sim1:1:0:0): TEST UNIT READY. CDB: 0 0 0 0 0 0 
: (pass4:umass-sim1:1:0:0): CAM Status: SCSI Status Error
: (pass4:umass-sim1:1:0:0): SCSI Status: Check Condition
: (pass4:umass-sim1:1:0:0): UNIT ATTENTION asc:28,0
: (pass4:umass-sim1:1:0:0): Not ready to ready change, medium may have changed
: Exit 1
: [72]cicely13# camcontrol tur -n da -u 4 -v
: Unit is ready
: 
: Those are both more or less random flash card readers, so it seems that
: even cheap devices work.

Maybe we should move the TUR processing into daopen?  Right now we
assume that the values from XPT_CALC_GEOMETRY are invairant and we
never need to check to see if they've changed.  Since daopen isn't
usually called that often, optimizing it isn't really much of an
issue.

Warner