Some targets may return slight variations of PQ and PDT to indicate
no LUN mapped. USB UFI setting PDT=0x1f but having reserved bits for
PQ is one example, and NetApp targets returning PQ=1 and PDT=0x1f is
another. Both instances seem like reasonable responses according to
SPC-3 and UFI specs.
The current scsi_probe_and_add_lun() code adds a scsi_device
for targets that return PQ=1 and PDT=0x1f. This causes LUNs of type
"UNKNOWN" to show up in /proc/scsi/scsi when no LUNs are mapped.
In addition, subsequent rescans fail to recognize LUNs that may be
added on the target, unless preceded by a write to the delete attribute
of the "UNKNOWN" LUN.
This patch addresses this problem by skipping over the scsi_add_lun()
when PQ=1,PDT=0x1f is encountered, and just returns
SCSI_SCAN_TARGET_PRESENT.
Signed-off-by: Dave Wysochanski <davidw@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
--- a/drivers/scsi/scsi_scan.c 2006-07-15 17:53:08.000000000 -0400
+++ b/drivers/scsi/scsi_scan.c 2006-08-09 14:01:20.000000000 -0400
@@ -943,11 +943,26 @@ static int scsi_probe_and_add_lun(struct
}
/*
- * Non-standard SCSI targets may set the PDT to 0x1f (unknown or
- * no device type) instead of using the Peripheral Qualifier to
- * indicate that no LUN is present. For example, USB UFI does this.
+ * Some targets may set slight variations of PQ and PDT to signal
+ * that no LUN is present, so don't add sdev in these cases.
+ * Two specific examples are:
+ * 1) NetApp targets: return PQ=1, PDT=0x1f
+ * 2) USB UFI: returns PDT=0x1f, with the PQ bits being "reserved"
+ * in the UFI 1.0 spec (we cannot rely on reserved bits).
+ *
+ * References:
+ * 1) SCSI SPC-3, pp. 145-146
+ * PQ=1: "A peripheral device having the specified peripheral
+ * device type is not connected to this logical unit. However, the
+ * device server is capable of supporting the specified peripheral
+ * device type on this logical unit."
+ * PDT=0x1f: "Unknown or no device type"
+ * 2) USB UFI 1.0, p. 20
+ * PDT=00h Direct-access device (floppy)
+ * PDT=1Fh none (no FDD connected to the requested logical unit)
*/
- if (starget->pdt_1f_for_no_lun && (result[0] & 0x1f) == 0x1f) {
+ if (((result[0] >> 5) == 1 || starget->pdt_1f_for_no_lun) &&
+ (result[0] & 0x1f) == 0x1f) {
SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO
"scsi scan: peripheral device type"
" of 31, no device added\n"));
-
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