scsi_scan: Restrict sequential scan to 256 LUNs
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>
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 8564bdc..a02f7b0 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1235,6 +1235,12 @@
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.