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Subject[PATCH 3.12 065/142] scsi_scan: Restrict sequential scan to 256 LUNs
Date
From: Hannes Reinecke <hare@suse.de>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 22ffeb48b7584d6cd50f2a595ed6065d86a87459 upstream.

Sequential scan for more than 256 LUNs is very fragile as
LUNs might not be numbered sequentially after that point.

SAM revisions later than SCSI-3 impose a structure on
LUNs larger than 256, making LUN numbers between 256
and 16384 illegal.
SCSI-3, however allows for plain 64-bit numbers with
no internal structure.

So restrict sequential LUN scan to 256 LUNs and add a
new blacklist flag 'BLIST_SCSI3LUN' to scan up to
max_lun devices.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ewan Milne <emilne@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/scsi/scsi_scan.c | 6 ++++++
include/scsi/scsi_devinfo.h | 2 ++
2 files changed, 8 insertions(+)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 4109530e92a0..bfad3586d914 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1236,6 +1236,12 @@ static void scsi_sequential_lun_scan(struct scsi_target *starget,
max_dev_lun = min(8U, max_dev_lun);

/*
+ * Stop scanning at 255 unless BLIST_SCSI3LUN
+ */
+ if (!(bflags & BLIST_SCSI3LUN))
+ max_dev_lun = min(256U, max_dev_lun);
+
+ /*
* We have already scanned LUN 0, so start at LUN 1. Keep scanning
* until we reach the max, or no LUN is found and we are not
* sparse_lun.
diff --git a/include/scsi/scsi_devinfo.h b/include/scsi/scsi_devinfo.h
index 447d2d7466fc..8670c04e199e 100644
--- a/include/scsi/scsi_devinfo.h
+++ b/include/scsi/scsi_devinfo.h
@@ -32,4 +32,6 @@
#define BLIST_ATTACH_PQ3 0x1000000 /* Scan: Attach to PQ3 devices */
#define BLIST_NO_DIF 0x2000000 /* Disable T10 PI (DIF) */
#define BLIST_SKIP_VPD_PAGES 0x4000000 /* Ignore SBC-3 VPD pages */
+#define BLIST_SCSI3LUN 0x8000000 /* Scan more than 256 LUNs
+ for sequential scan */
#endif
--
2.1.0


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