SCSI & usb-storage: add flags for VPD pages and REPORT LUNS

This patch (as1507) adds a skip_vpd_pages flag to struct scsi_device
and a no_report_luns flag to struct scsi_target.  The first is used to
control whether sd will look at VPD pages for information on block
provisioning, limits, and characteristics.  The second prevents
scsi_report_lun_scan() from issuing a REPORT LUNS command.

The patch also modifies usb-storage to set the new flag bits for all
USB devices and targets, and to stop adjusting the scsi_level value.

Historically we have seen that USB mass-storage devices often don't
support VPD pages or REPORT LUNS properly.  Until now we have avoided
these things by setting the scsi_level to SCSI_2 for all USB devices.
But this has the side effect of storing the LUN bits into the second
byte of each CDB, and now we have a report of a device which doesn't
like that.  The best solution is to stop abusing scsi_level and
instead have separate flags for VPD pages and REPORT LUNS.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Perry Wagle <wagle@mac.com>
CC: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/scsi/scsi_scan.c

@@ -1295,6 +1295,7 @@ EXPORT_SYMBOL(int_to_scsilun);
  *   LUNs even if it's older than SCSI-3.
  *   If BLIST_NOREPORTLUN is set, return 1 always.
  *   If BLIST_NOLUN is set, return 0 always.
+ *   If starget->no_report_luns is set, return 1 always.
  *
  * Return:
  *     0: scan completed (or no memory, so further scanning is futile)
@@ -1321,6 +1322,7 @@ static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
 	 * Only support SCSI-3 and up devices if BLIST_NOREPORTLUN is not set.
 	 * Also allow SCSI-2 if BLIST_REPORTLUN2 is set and host adapter does
 	 * support more than 8 LUNs.
+	 * Don't attempt if the target doesn't support REPORT LUNS.
 	 */
 	if (bflags & BLIST_NOREPORTLUN)
 		return 1;
@@ -1332,6 +1334,8 @@ static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
 		return 1;
 	if (bflags & BLIST_NOLUN)
 		return 0;
+	if (starget->no_report_luns)
+		return 1;
 
 	if (!(sdev = scsi_device_lookup_by_target(starget, 0))) {
 		sdev = scsi_alloc_sdev(starget, 0, NULL);

drivers/scsi/sd.c

@@ -2349,7 +2349,7 @@ static int sd_try_extended_inquiry(struct scsi_device *sdp)
 	 * some USB ones crash on receiving them, and the pages
 	 * we currently ask for are for SPC-3 and beyond
 	 */
-	if (sdp->scsi_level > SCSI_SPC_2)
+	if (sdp->scsi_level > SCSI_SPC_2 && !sdp->skip_vpd_pages)
 		return 1;
 	return 0;
 }

drivers/usb/storage/scsiglue.c

@@ -197,6 +197,9 @@ static int slave_configure(struct scsi_device *sdev)
 		 * page x08, so we will skip it. */
 		sdev->skip_ms_page_8 = 1;
 
+		/* Some devices don't handle VPD pages correctly */
+		sdev->skip_vpd_pages = 1;
+
 		/* Some disks return the total number of blocks in response
 		 * to READ CAPACITY rather than the highest block number.
 		 * If this device makes that mistake, tell the sd driver. */
@@ -217,16 +220,6 @@ static int slave_configure(struct scsi_device *sdev)
 		if (sdev->scsi_level > SCSI_SPC_2)
 			us->fflags |= US_FL_SANE_SENSE;
 
-		/* Some devices report a SCSI revision level above 2 but are
-		 * unable to handle the REPORT LUNS command (for which
-		 * support is mandatory at level 3).  Since we already have
-		 * 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. */
-		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,
 		 * recoverable or not.  Setting this flag tells the SCSI
@@ -283,6 +276,18 @@ static int slave_configure(struct scsi_device *sdev)
 	return 0;
 }
 
+static int target_alloc(struct scsi_target *starget)
+{
+	/*
+	 * Some USB drives don't support REPORT LUNS, even though they
+	 * report a SCSI revision level above 2.  Tell the SCSI layer
+	 * not to issue that command; it will perform a normal sequential
+	 * scan instead.
+	 */
+	starget->no_report_luns = 1;
+	return 0;
+}
+
 /* queue a command */
 /* This is always called with scsi_lock(host) held */
 static int queuecommand_lck(struct scsi_cmnd *srb,
@@ -546,6 +551,7 @@ struct scsi_host_template usb_stor_host_template = {
 
 	.slave_alloc =			slave_alloc,
 	.slave_configure =		slave_configure,
+	.target_alloc =			target_alloc,
 
 	/* lots of sg segments can be handled */
 	.sg_tablesize =			SCSI_MAX_SG_CHAIN_SEGMENTS,

include/scsi/scsi_device.h

@@ -136,6 +136,7 @@ struct scsi_device {
 	unsigned use_10_for_ms:1; /* first try 10-byte mode sense/select */
 	unsigned skip_ms_page_8:1;	/* do not use MODE SENSE page 0x08 */
 	unsigned skip_ms_page_3f:1;	/* do not use MODE SENSE page 0x3f */
+	unsigned skip_vpd_pages:1;	/* do not read VPD pages */
 	unsigned use_192_bytes_for_3f:1; /* ask for 192 bytes from page 0x3f */
 	unsigned no_start_on_add:1;	/* do not issue start on add */
 	unsigned allow_restart:1; /* issue START_UNIT in error handler */
@@ -248,6 +249,8 @@ struct scsi_target {
 						 * for the device at a time. */
 	unsigned int		pdt_1f_for_no_lun:1;	/* PDT = 0x1f
 						 * means no lun present. */
+	unsigned int		no_report_luns:1;	/* Don't use
+						 * REPORT LUNS for scanning. */
 	/* commands actually active on LLD. protected by host lock. */
 	unsigned int		target_busy;
 	/*