[SCSI] Don't add scsi_device for devices that return PQ=1, PDT=0x1f (84961f28) · Commits · 戴 / test

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@netapp.com> Signed-off-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_scan.c

+19 −4

Original line number	Diff line number	Diff line
		@@ -893,11 +893,26 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
		}

		/*
		* 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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