[PATCH v10 13/15] scsi: add BLIST_NO_LUN_1F blacklist flag

[Phil Pemberton]

Some multi-LUN devices report unpopulated LUNs with PQ=0/PDT=0x1f.
SCSI scanning adds these as spurious "No Device" entries.

Add BLIST_NO_LUN_1F to set pdt_1f_for_no_lun from scsi_devinfo before
scsi_probe_and_add_lun() checks PDT=0x1f. Setting it here also covers
LUN 0.

Give pdt_1f_for_no_lun its own bool. Sharing bitfield storage with
expecting_lun_change allows scan-time writes and concurrent I/O updates
to overwrite each other.

Assisted-by: LLM
Signed-off-by: Phil Pemberton <philpem@xxxxxxxxxxxxx>
---
 drivers/scsi/scsi_scan.c    | 3 +++
 include/scsi/scsi_device.h  | 4 ++--
 include/scsi/scsi_devinfo.h | 6 +++---
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 0f0f243c2561..e34824623294 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1298,6 +1298,9 @@ static int scsi_probe_and_add_lun(struct Scsi_Host *shost,
 	 * PDT=00h Direct-access device (floppy)
 	 * PDT=1Fh none (no FDD connected to the requested logical unit)
 	 */
+	if (bflags & BLIST_NO_LUN_1F)
+		starget->pdt_1f_for_no_lun = 1;
+
 	if (((result[0] >> 5) == 1 || starget->pdt_1f_for_no_lun) &&
 	    (result[0] & 0x1f) == 0x1f &&
 	    !scsi_is_wlun(lun)) {
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 8694eeadd753..a81a7c8cce18 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -360,13 +360,13 @@ struct scsi_target {
 	unsigned int		single_lun:1;	/* Indicates we should only
 						 * allow I/O to one of the luns
 						 * 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. */
 	unsigned int		expecting_lun_change:1;	/* A device has reported
 						 * a 3F/0E UA, other devices on
 						 * the same target will also. */
+	/* Keep scan-time writes separate from I/O-updated bitfields. */
+	bool			pdt_1f_for_no_lun; /* PDT = 0x1f means no LUN. */
 	/* commands actually active on LLD. */
 	atomic_t		target_busy;
 	atomic_t		target_blocked;
diff --git a/include/scsi/scsi_devinfo.h b/include/scsi/scsi_devinfo.h
index 1d79a3b536ce..6957b0705510 100644
--- a/include/scsi/scsi_devinfo.h
+++ b/include/scsi/scsi_devinfo.h
@@ -34,7 +34,8 @@
 #define BLIST_NOSTARTONADD	((__force blist_flags_t)(1ULL << 12))
 /* do not ask for VPD page size first on some broken targets */
 #define BLIST_NO_VPD_SIZE	((__force blist_flags_t)(1ULL << 13))
-#define __BLIST_UNUSED_14	((__force blist_flags_t)(1ULL << 14))
+/* PDT 0x1f with PQ 0 means no LUN present (e.g. some ATAPI multi-LUN) */
+#define BLIST_NO_LUN_1F		((__force blist_flags_t)(1ULL << 14))
 #define __BLIST_UNUSED_15	((__force blist_flags_t)(1ULL << 15))
 #define __BLIST_UNUSED_16	((__force blist_flags_t)(1ULL << 16))
 /* try REPORT_LUNS even for SCSI-2 devs (if HBA supports more than 8 LUNs) */
@@ -77,8 +78,7 @@
 #define __BLIST_HIGH_UNUSED (~(__BLIST_LAST_USED | \
 			       (__force blist_flags_t) \
 			       ((__force __u64)__BLIST_LAST_USED - 1ULL)))
-#define __BLIST_UNUSED_MASK (__BLIST_UNUSED_14 | \
-			     __BLIST_UNUSED_15 | \
+#define __BLIST_UNUSED_MASK (__BLIST_UNUSED_15 | \
 			     __BLIST_UNUSED_16 | \
 			     __BLIST_UNUSED_24 | \
 			     __BLIST_UNUSED_27 | \
-- 
2.43.0