usb-storage: SCSI level fixes

This patch (as835) removes from usb-storage the code which sets all
devices to a SCSI level of at least SCSI-2.  The original reasons for
doing this no longer apply, and in fact it prevents certain kinds of
ATA pass-thru commands from being used.

The patch also marks CB and CBI devices that are SCSI-0 (legacy SCSI)
as being single-LUN, since the combined SCSI-over-USB transport
protocol has no way to convey LUN information to these devices.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index e1072d5..70234f5 100644 (file)
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -110,23 +110,6 @@ static int slave_configure(struct scsi_device *sdev)
         * the end, scatter-gather buffers follow page boundaries. */
        blk_queue_dma_alignment(sdev->request_queue, (512 - 1));
 
-       /* Set the SCSI level to at least 2.  We'll leave it at 3 if that's
-        * what is originally reported.  We need this to avoid confusing
-        * the SCSI layer with devices that report 0 or 1, but need 10-byte
-        * commands (ala ATAPI devices behind certain bridges, or devices
-        * which simply have broken INQUIRY data).
-        *
-        * NOTE: This means /dev/sg programs (ala cdrecord) will get the
-        * actual information.  This seems to be the preference for
-        * programs like that.
-        *
-        * NOTE: This also means that /proc/scsi/scsi and sysfs may report
-        * the actual value or the modified one, depending on where the
-        * data comes from.
-        */
-       if (sdev->scsi_level < SCSI_2)
-               sdev->scsi_level = sdev->sdev_target->scsi_level = SCSI_2;
-
        /* Many devices have trouble transfering more than 32KB at a time,
         * while others have trouble with more than 64K. At this time we
         * are limiting both to 32K (64 sectores).
@@ -176,7 +159,9 @@ static int slave_configure(struct scsi_device *sdev)
                 * a Get-Max-LUN request, we won't lose much by setting the
                 * revision level down to 2.  The only devices that would be
                 * affected are those with sparse LUNs. */
-               sdev->scsi_level = sdev->sdev_target->scsi_level = SCSI_2;
+               if (sdev->scsi_level > SCSI_2)
+                       sdev->sdev_target->scsi_level =
+                                       sdev->scsi_level = SCSI_2;
 
                /* USB-IDE bridges tend to report SK = 0x04 (Non-recoverable
                 * Hardware Error) when any low-level error occurs,
@@ -194,6 +179,16 @@ static int slave_configure(struct scsi_device *sdev)
                sdev->use_10_for_ms = 1;
        }
 
+       /* The CB and CBI transports have no way to pass LUN values
+        * other than the bits in the second byte of a CDB.  But those
+        * bits don't get set to the LUN value if the device reports
+        * scsi_level == 0 (UNKNOWN).  Hence such devices must necessarily
+        * be single-LUN.
+        */
+       if ((us->protocol == US_PR_CB || us->protocol == US_PR_CBI) &&
+                       sdev->scsi_level == SCSI_UNKNOWN)
+               us->max_lun = 0;
+
        /* Some devices choke when they receive a PREVENT-ALLOW MEDIUM
         * REMOVAL command, so suppress those commands. */
        if (us->flags & US_FL_NOT_LOCKABLE)