[PATCH 1/3] Try LUN 1 and use bflags

[Kurt Garloff <garloff@suse.de>]

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From: Kurt Garloff <garloff@suse.de>
Subject: Tolerate PQ 3 at LUN 0 for scanning
Patch-mainline: 
References: 158532

Some devices report a peripheral qualifier of 3 for LUN 0; with the original
code, we would still try a REPORT_LUNS scan (if SCSI level is >= 3 or if we 
have the BLIST_REPORTLUNS2 passed in), but NOT any sequential scan.
Also, the device at LUN 0 (which is not connected according to the PQ) is not
registered with the OS.

Unfortunately, SANs exist that are SCSI-2 and do NOT support REPORT_LUNS, but
report a unknown device with PQ 3 on LUN 0. We still need to scan them, and
most probably we even need BLIST_SPARSELUN (and BLIST_LARGELUN). See the bug
reference for an infamous example.

This is patch 1/3:
If we end up in sequential scan, at least try LUN 1 for devices
that reported a PQ of 3 for LUN 0.
Also return blacklist flags, even for PQ3 devices.

Acked-by: 
Signed-off-by: Kurt Garloff <garloff@suse.de>

Index: linux-2.6.16/drivers/scsi/scsi_scan.c
===================================================================
--- linux-2.6.16.orig/drivers/scsi/scsi_scan.c
+++ linux-2.6.16/drivers/scsi/scsi_scan.c
@@ -860,6 +860,8 @@ static int scsi_probe_and_add_lun(struct
 	if (scsi_probe_lun(sdev, result, result_len, &bflags))
 		goto out_free_result;
 
+	if (bflagsp)
+		*bflagsp = bflags;
 	/*
 	 * result contains valid SCSI INQUIRY data.
 	 */
@@ -887,8 +889,6 @@ static int scsi_probe_and_add_lun(struct
 			sdev->lockable = 0;
 			scsi_unlock_floptical(sdev, result);
 		}
-		if (bflagsp)
-			*bflagsp = bflags;
 	}
 
  out_free_result:
@@ -945,11 +945,13 @@ static void scsi_sequential_lun_scan(str
 		sparse_lun = 0;
 
 	/*
-	 * If not sparse lun and no device attached at LUN 0 do not scan
-	 * any further.
-	 */
+	 * If LUN0 did respond, but did not have an attachable LUN (PQ=3),
+	 * we do NOT abort the sequential scan yet, let's try one more
+	 * LUN and only abort the scan if we don't find anything there.
+	 * 
 	if (!sparse_lun && (lun0_res != SCSI_SCAN_LUN_PRESENT))
 		return;
+	 */
 
 	/*
 	 * If less than SCSI_1_CSS, and no special lun scaning, stop
-- 
Kurt Garloff, Head Architect Linux R&D, Novell Inc.

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